INBR 7 - Multidicipline Self Assesment Examination Flashcards

Question

25. Katup manakah diantara di bawah ini yang merupakan katup pengatur aliran? A. Katup Orbis-Sigma B. Katup delta medical PS C. Katup horisontal-vertikal kordis D. Katup terprogram Goldman Hakim E. Katup Holter-Haussner

Answer 1

A. Some of the valves currently used in clinical practice include the static (Holter-Hausner valve, Denver shunt, Codman Uni-Shunt) and programmable (Codman Medos, Sophy valve) differential pressure valves, flow-regulated valves (Orbis Sigma), and gravity-actuated valves (Cordis horizontal-vertical valve). The PS Medical Delta valve consists of an antisiphoning device just distal to a differential pressure valve. More recently Codman has introduced the Hakim programmable valve with a Siphon-Guard valve, while Medtronic has introduced the Strata valve, a programmable valve with variable pressure settings that can be coupled with their Delta valve antisiphoning device. The valves described above all use different approaches to control flow through the valve system and limit overshunting. Differential pressure valves open when the pressure at the inlet is higher than that the outlet by a preselected amount. Programmable differential pressure valves act in a similar fashion except that the surgeon can change the opening pressure with an external device, which often obviates the need for surgical shunt revision. Flow-regulated valves use a three-stage resistance mechanism to keep the flow rate through the valve constant. Gravity-actuated valves attempt to decrease siphoning by increasing opening pressure with the assistance of gravity when a patient sits or stands. Cordis horizontal-vertical valves are gravity-actuated valves that have traditionally been used with lumboperitoneal shunts (Youmans, pp. 33 76-3379; Albright, pp. 79-80; Wi lkins, pp. 3647-3651; American Society of Pediatric Neu rosurgeons, p p . 506-508; Committee on Education i n Neurological Surgery, pp. 137-138) .

Answer 2

C The process of celltilar migration typically occurs between the second and fifth gestational months . Faulty cellular migration can result in heterotopias, callosal agenesis, lissencephaly, pachygyria/polymicrog\Tia, and openor closed-lip schizencephaly. Note the prominent cleft (open-lip) that is lined entirely by gray matter on this sagittal MRI. Porencephalic clefts are predominately lined by gliotic white matter (Osborne DN, pp. 5 2 - 55 ) .

Answer 3

D The process of celltilar migration typically occurs between the second and fifth gestational months . Faulty cellular migration can result in heterotopias, callosal agenesis, lissencephaly, pachygyria/polymicrog\Tia, and openor closed-lip schizencephaly. Note the prominent cleft (open-lip) that is lined entirely by gray matter on this sagittal MRI. Porencephalic clefts are predominately lined by gliotic white matter (Osborne DN, pp. 5 2 - 55 ) .

Answer 4

E. Proopiomelanocortin (PO.MC) gives rise to betalipotropin and ACTH. The sequences of beta-endorphin and melanocyte-stimulating hormone are contained in beta-lipotropin ( Kandel, p. 487).

Answer 5

D. This patient has developed diabetes insipidus (DI). Criteria frequently used to make the diagnosis include: urine osmolarity 50 to 150 mOsm/L, specific gravity 1.001 to 1 .005, urine output :2 250 to 300 cc/hr for 3 consecutive hours, and progressively increasing Na• levels on serial lab draws. This patient should receive aqueous vasopressin (Pitressin) (IVP/IM/SQ), as the lipid-soluble form is poorly absorbed compared to the aqueous form. This patient would likely not tolerate oral DDA VP due to her nausea, and a n asogastric tube is generally contraindicated after a transsphenoidal operation. Fludrocortisone acetate acts directly on the renal tubules to increase sodium absorption. This medication, along with urea, would be more applicable for patients with cerebral salt wasting or SIADH. Complications with fludrocortisone acetate include pulmonary edema, hypokalemia, and hypertension (Greenberg, p p . 20-23; Committee on Education i n Neurological Surgery, p . 99) .

Answer 6

C. This EEG depicts normal posterior dominant rhythm ("alpha rhythm") in a healthy adult man, maximal in the posterior head regions when the eyes are closed ( Rowa n , pp. 2 5 - 26).

Answer 7

C. A number of extracranial-to-intracranial anastomoses exist that may potentially provide collateral blood flow to the orbit and preserve vision after occlusion of the internal carotid or ophthalmic arteries. This collateral flow is mainly supplied by branches of the external carotid artery, including the internal maxillary (most important) and facial arteries, via their extensive ethmoid, ophthalmic, and cavernous carotid collaterals. Although this collateral filling is not always evident on angiography, this patient's angiogram is more likely to show poor collateral flow to the globe from the ma.'Cillary or facial arteries, considering her symptomatology. The ascending pharyngeal artery does not usually provide collateral blood supply to the globe, while vasospasm would be highly unlikely in this setting. There should be other accompanying neurologic deficits if there 1vas complete occlusion of the right internal carotid artery with inadequate collateral feeding of that hemisphere (Osborn D N , p. 397 ) .

Answer 8

D One of the hallmarks of pilocytic astrocytomas is their relatively indolent growth rate with low mitotic acti\•ity . .Management typically includes gross total resection, if possible, followed by radiation therapy for recurrence. In some cases, invasion of the brainstem and/or cranial nervesprecludes gross total resection. Macroscopic features common to these tumors include the formation of a cyst with a solid mural nodule. Tumors without cyst wall enhancement are typically adequately treated with mural nodule excision alone, while tumors with a thickened, enhancing cyst wall are best managed with gross total excision. Microscopically, these tumors show a biphasic pattern consisting of bipolar, highly fibrillated (or piloid) cells with Rosenthal fibers and a loose-knit cystic component associated with granular bodies or protein droplets. The arrow depicts Rosenthal fibers, which are ubiquitin a

Answer 9

C One of the hallmarks of pilocytic astrocytomas is their relatively indolent growth rate with low mitotic acti\•ity . .Management typically includes gross total resection, if possible, followed by radiation therapy for recurrence. In some cases, invasion of the brainstem and/or cranial nervesprecludes gross total resection. Macroscopic features common to these tumors include the formation of a cyst with a solid mural nodule. Tumors without cyst wall enhancement are typically adequately treated with mural nodule excision alone, while tumors with a thickened, enhancing cyst wall are best managed with gross total excision. Microscopically, these tumors show a biphasic pattern consisting of bipolar, highly fibrillated (or piloid) cells with Rosenthal fibers and a loose-knit cystic component associated with granular bodies or protein droplets. The arrow depicts Rosenthal fibers, which are ubiquitin a

Answer 10

C. A 6-month-old infant is able to transfer objects from hand to hand, support most of his weight, lift his head off the table prior to being pulled up, turn his head to voice, and reach for objects ( Rudolph, p. 15).

Answer 11

D. The suck reflex can be elicited in infants below 4 months of age and consists of bursts of upward tongue pressure and buccinator contraction when the examiner places a clean finger or pacifier into the infants mouth. The tonic neck reflex (typically disappears by 6 months) involves turning the head of a supine infant to one side. The opposite arm should extend 90 degrees from the trunk and the opposite leg should extend downward ("fencing position"). Placing a finger in an infant's hand or under the toes can elicit the palmar grasp or plantar reflex, respectively. The palmar grasp reflex usually disappears by 6 months, while the plantar reflex is often present until 10 months of age . The stepping/ placing reflex is produced when the baby is held upright and the dorsal edge of the foot is allowed to brush against an object such as a bed or table. Infants less than 6 weeks of age should flex the knee and lift the foot. The ventral suspension (Landau) reflex results in extension of the head, trunk, and hips and knee flexion when an infant is supported on the examiner's hand in a prone position. This reflex does not usually disappear until the age of 2 years. The Moro reflex occurs when the baby is placed in the supine position and the examiner lifts the baby's head by placing his or her hand under it. Sudden release of the head a few centimeters toward the bed should elicit a complete Moro response in infants less than 3 to 4 months of age . It consists of abduction of the arms at the shoulder, extension of the forearms at the elbow, and extension of the fingers, followed by arm adduction at the shoulders. Additional reflexes include the crossed adductor (disappears by 7 months), parachute, and neck righting (disappears by 2 years) reflexes (Rudolph, p . 15).

Answer 12

C Extensive removal of the anterior clinoid process and optic strut (roof of the optic canal), as well as sectioning of the falciform ligament and distal dural ring is often required for successful clipping of large ophthalmic segment CHAPTER 8 Multidisciplinary Self-Assessment Answers 26.7 aneurysms. Attempts to clip large and giant paraclinoid/ ophthalmic artery aneurysms with broad necks without this degree of exposure may place the ophthalmic and internal carotid arteries in jeopardy of clip-induced stenosis/ocqh.Ision. Ophthalmic segment aneurysms typically arise beneath the lateral aspect of the optic nerve, which initially results in compression of temporal fibers and an ipsilateral monocular superior nasal quadrantanopsia. With aneurysmal enlargement, the optic nerve is deflected further medially and superiorly against the rigid falciform ligament, which causes superior fiber compression and a monocular inferior nasal field cut (Greenberg, p. 783; Wilkins, pp. 2291-2299; Samson, pp. 41- 53) .

Answer 13

E Extensive removal of the anterior clinoid process and optic strut (roof of the optic canal), as well as sectioning of the falciform ligament and distal dural ring is often required for successful clipping of large ophthalmic segment CHAPTER 8 Multidisciplinary Self-Assessment Answers 26.7 aneurysms. Attempts to clip large and giant paraclinoid/ ophthalmic artery aneurysms with broad necks without this degree of exposure may place the ophthalmic and internal carotid arteries in jeopardy of clip-induced stenosis/ocqh.Ision. Ophthalmic segment aneurysms typically arise beneath the lateral aspect of the optic nerve, which initially results in compression of temporal fibers and an ipsilateral monocular superior nasal quadrantanopsia. With aneurysmal enlargement, the optic nerve is deflected further medially and superiorly against the rigid falciform ligament, which causes superior fiber compression and a monocular inferior nasal field cut (Greenberg, p. 783; Wilkins, pp. 2291-2299; Samson, pp. 41- 53) .

Answer 14

C. Identification of the oligodendroglia! component on permanent section is usually aided by the classic "fried egg" appearance of the perinuclear halo. This develops as a consequence of the fixation process; it is not evident on smear or frozen examination and may be absent in rapidly fixed tissue and in paraffin sections made from frozen material (Ellison , pp. 641-645; WHO, pp. 56-6 1) .

Answer 15

E. The spinocerebellar tracts convey unconscious proprioception from Golgi tendon organs, muscle spindles, and joint receptors in the periphery to the CNS. Dorsal spinocerebellar fibers (C8-L2) enter the medial aspect of the dorsal roots and synapse in the dorsal nucleus of Clarke. Second-order neurons in Clarke's nucleus then project to the vermis and paramedian lobule of the cerebellum via the inferior cerebellar peduncle, where they terminate as mossy fibers. Above the level of C8, Ia and lb afferents enter the fasciculus cuneatus and synapse in the accessory cuneate nucleus of the medulla (the equivalent of Clarke's nucleus of the spinal cord). Second-order neurons then enter the cerebellum (cuneocerebellar fibers) via the inferior cerebellar peduncle before synapsing in the cerebellum. The ventral spinocerebellar tract is a crossed tract that originates in Rexed laminae V to VII in the lower lumbar and coccygeal levels. This tract then decussates a second time in the pons before entering the cerebellum as mossy fibers via the superior cerebellar peduncle (Carpenter, pp. 90-94).

Answer 16

A. The cortical representation for macular retinal vision is located in the occipital poles. The primary visual cortex (area 1 7 ) is located along the upper and lower banks of the calcarine sulcus. Layer IV of the primary visual cortex is particularly prominent and is known as the "band of Gennari. " The occipital poles often receive collateral blood flow from the middle cerebral arteries, which is thought to account for macular sparing with field cuts that originate from cortical infarctions secondary to posterior cereb

Answer 17

C. The superior olivary nuclei receive the ventral acoustic striae and contain third-order auditory neurons that subsequently project to the contralateral lateral lemniscus. The superior olives are the initial sites of binaural convergence within the auditory pathway ( Kandel, pp. 606-608) .

Answer 18

A. The angiogram depicts a right posterior carotid wall aneurysm as well as extravasation of contrast dye from the aneurysm in a patient about to be treated with GDC embolization (mi

Answer 19

A . Note the prominent ST-segment elevation i n leads V1 through V6 on this EGG, depicting an anterior wall myocardial infarction. In general, ST-segment and T-wave changes appear over the first minutes to hours of an infarction, and Q waves appear over hours to days. An evolving myocardial infarction may first manifest with peaked T waves followed by ST segment elevation and T-wave inversion. Eventually Q waves may appear. In a large anterior wall infarction, these changes are most apparent in leads V1 through V6, while in an inferior infarction, these changes often occur in leads II, III, and aVF. Of note, if a patient's T waves are chronically inverted, the peaking may make them appear normal-a process referred to as pseudonormalization. T waves are the least reliable of ST- and T-\\'ave segment abnormalities because many• noncardiac events may influence them (i.e., elevated W). Dying myocardial cells release their enzymes into the bloodstream, and the increased concentration should be confirmed in the peripheral _ blood ( Fishman, pp. 9 - 24; Marino, pp. 301-313 ) .

Answer 20

C The clinical history and 1UU are most consistent with a cystic craniopharyngioma. The modestly elevated prolactin level is likely the result of the "stalk effect," whereby injury of the hypothalamus or pituitary stalk (i.e., from large tumors) results in modest ele,•ations of prolactin from reduced prolactin inhibitory factor levels (dopamine) . As a general rule, prolactin levels \> 150 ng/mL are rarely secondary to a stalk effect, whereas le,•els

Answer 21

B The clinical history and 1UU are most consistent with a cystic craniopharyngioma. The modestly elevated prolactin level is likely the result of the "stalk effect," whereby injury of the hypothalamus or pituitary stalk (i.e., from large tumors) results in modest ele,•ations of prolactin from reduced prolactin inhibitory factor levels (dopamine) . As a general rule, prolactin levels \> 150 ng/mL are rarely secondary to a stalk effect, whereas le,•els

Answer 22

E. Sarcoidosis, not Beh9et's syndrome, is associated with elevated levels of angiotensin-converting enzyme ( Merritt, pp. 12 1 - 122).

Answer 23

B ( Merritt, pp. 613, 7 1 1 , 723-724, 7 2 7-728, 766; Greenberg, pp. 72-75, 78-79) .

Answer 24

A ( Merritt, pp. 613, 7 1 1 , 723-724, 7 2 7-728, 766; Greenberg, pp. 72-75, 78-79) .

Answer 25

E ( Merritt, pp. 613, 7 1 1 , 723-724, 7 2 7-728, 766; Greenberg, pp. 72-75, 78-79) .

Answer 26

C ( Merritt, pp. 613, 7 1 1 , 723-724, 7 2 7-728, 766; Greenberg, pp. 72-75, 78-79) .

Answer 27

D ( Merritt, pp. 613, 7 1 1 , 723-724, 7 2 7-728, 766; Greenberg, pp. 72-75, 78-79) .

Answer 28

D. Note the abnormally thickened stalk with high signal intensity on this coronal MRl depicting Langerhans' cell histiocytosis. The etiology of this condition is unknown, but it is believed to result from overproliferation of an antigen-presenting dendritic cell of bone marrow origin. Although it is usually treated as a neoplastic process, some speculate that it is due to malfunction of the immune system. Other manifestations of this disease may include lytic skull lesions (approximately 80% of cases) as well as hematopoietic, hepatic, and pulmonary abnormalities. A pathognomic finding of this condition on electron microscopy is the presence of Birbeck granules, a unique organelle of the Langerhans' cell ( Ramsey, pp. 381-385; Merritt, p. 872) .

Answer 29

C. Note the abnormally thickened stalk with high signal intensity on this coronal MRl depicting Langerhans' cell histiocytosis. The etiology of this condition is unknown, but it is believed to result from overproliferation of an antigen-presenting dendritic cell of bone marrow origin. Although it is usually treated as a neoplastic process, some speculate that it is due to malfunction of the immune system. Other manifestations of this disease may include lytic skull lesions (approximately 80% of cases) as well as hematopoietic, hepatic, and pulmonary abnormalities. A pathognomic finding of this condition on electron microscopy is the presence of Birbeck granules, a unique organelle of the Langerhans' cell ( Ramsey, pp. 381-385; Merritt, p. 872) .

Answer 30

A. Note the abnormally thickened stalk with high signal intensity on this coronal MRl depicting Langerhans' cell histiocytosis. The etiology of this condition is unknown, but it is believed to result from overproliferation of an antigen-presenting dendritic cell of bone marrow origin. Although it is usually treated as a neoplastic process, some speculate that it is due to malfunction of the immune system. Other manifestations of this disease may include lytic skull lesions (approximately 80% of cases) as well as hematopoietic, hepatic, and pulmonary abnormalities. A pathognomic finding of this condition on electron microscopy is the presence of Birbeck granules, a unique organelle of the Langerhans' cell ( Ramsey, pp. 381-385; Merritt, p. 872) .

Answer 31

C Acoustic neuroma. Note the palisading of nuclei (picket fence-like arrangement) separated by an anuclear area (arrow) on this photomicrograph, which depicts a Verocay body ( El lison, pp. 695- 699) .

Answer 32

A Acoustic neuroma. Note the palisading of nuclei (picket fence-like arrangement) separated by an anuclear area (arrow) on this photomicrograph, which depicts a Verocay body ( El lison, pp. 695- 699) .

Answer 33

A. A lesion of the MLF does not allow for transfer of information from the abducens nucleus (CN VI) to the oppositeoculomotor nucleus (CN III) and results in internuclear ophthalmoplegia (INO). It is characterized by deficient adduction during attempted conjugate gaze away from the side of the MLF lesion and monocular nystagmus of the abducting eye. An MLF lesion is on the same side as the eye with the adduction wealmess, and I TO is named for the side of the MLF lesion . A lesion in the nucleus of CN I I I would paralyze volitional movements and convergence (Kline, pp. 63-64).

Answer 34

B Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 35

A Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 36

A Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 37

C Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 38

D Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 39

C Compressive lesions of the ulnar nerve at the level of the elbow, forearm, or wrist can produce a "claw hand" (A) in severe cases. The ulnar half of the flexor digitorum profundus, lumbricals 3 and 4, the dorsal and palmar interossei, and the hypothenar muscles are typically paralyzed. When the metacarpophalangeal joints are extended, the distal and proximal interphalangeal joints cannot be extended because the interossei and half the lumbricals are not functional, which results in a "claw-like" posture. Laceration of the ulnar nerve in the wrist leaves the innervation of the ulnar side of the flexor digitorum profundus intact but can•also result in a claw hand. There is also loss of abduction of the thumb, so that a piece of paper cannot be held between the side of the thumb and the index finger. Lesions of the median nerve near the elbow can produce paralysis of the flexor digitorum superficialis, the flexor digitorum profundus I and II, the flexor pollicis longus, as well as the thenar muscles and lumbricals 1 and 2. This produces the "sign of benediction, " in which the index and middle fingers cannot flex and the thumb cannot be opposed. In addition, there may be numbness over the radial side of the palm and of the digits lateral to the center of the ring finger. C8 nerve root or anterior interosseous nerve injury causes weakness of the long flexors of the thumb (flexor pollicis longus), index and middle fingers (weak flexor digitorum profundus I and II), and the pronator quadratus. In trying to pinch the index finger and thumb, the terminal phalanges extend and instead of the tips, the pulps touch ("pinch sign," C) (April , pp. 98-100; Patten, pp. 285-296; Greenberg, p. 540) .

Answer 40

C Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 41

B Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 42

A Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 43

D Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 44

E Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 45

F Apraxia is defined as the inability to execute a normal volitional act despite the fact that the motor systems and mental status are relatively intact. Speech apraxia often results from a lesion near the posterior part of the inferior frontal gyrus (approximately area 44) , while writing apraxia or dysgraphia results from damage in the left angular gyrus. Dressing apraxia results from damage in the posterior right parietal lobe, while gait apraxia is usually associated with diffuse cerebral disease such as Alzheimer's disease. Lesions that affect the inferomedial part of the temporo-occipital region tend to cause an inability to recognize facial features (prosopagnosia) , while lesions of either parietal lobe may produce astereognosis, in which patients fail to recognize the forms of objects when felt but not when viewed (Brazis, pp. 481-508) .

Answer 46

C. The muscle stretch reflex is a monosynaptic circuit that is dependent on two neurons. Afferent axons serving the muscle stretch reflex synapse directly with ventral motaneurons (Carpenter, p. 79).

Answer 47

A. After a complete spinal cord i njury, all voluntary movements and sensation below the level of the lesion are lost, but a number of visceral reflexes may be preserved in some cases. A patient with a complete C2 spinal cord injury is unlikely to be able to breathe, since the spinal cord does not contain intrinsic circuitry for breathing. Retained reflexes may include micturition, defecation, peristalsis, and possibly even ejaculation, although there may be no sensation of the sexual act (Brazis, pp. 85-88; DeMyer, pp. 142 - 143 ) .

Answer 48

. A . The most important cranial nerve for palatal elevation is generally CN X. Interruption of the left CN X can causeparalysis of palatal elevation on the left side. Taste, swallowing, and phonation are also partially subserved by CN X; therefore an insult to this cranial nerve may result in problems with speech, swallowing, and taste. Salivation problems may be evident with deficits in CN VII and IX (Carpenter, pp. 137 - 144, 172 - 173)

Answer 49

I The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 50

J The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 51

F The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 52

B The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 53

G The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 54

C The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 55

I The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 56

H The major ascending tracts of the spinal cord (left) are the dorsal columns, spinothalamic tract, dorsal spinocerebellar tract, and ventral spinocerebellar tract. The dorsal columns convey tactile discrimination (Meissner corpuscles), vibration (pacinian corpuscle) , joint position sense (muscle spindles and Golgi tendon organs), and conscious proprioception . First-order neurons give rise to axons that ascend in the fasciculus cuneatus (A, upper extremity fibers) and gracilis (B, lower extremity), which terminate in the gracile and cuneate nuclei of the medulla. Second-order neurons, known as arcuate fibers, cross to the contralateral side as the medial lemniscus and ascend to the ventral posterolateral (VPL) nucleus of the thalamus. Synaptic connections are then made in the thalamus with third-order neurons, which travel through the posterior limb of the internal capsule to reach the postcentral gyrus of the cerebral cortex. Four groups of fibers have been distinguished in the anterolateral system (I) on the basis of their anatomic projections: spinothalamic, spinoreticular, spinomesencephalic, and spinotectal. First-order neurons of the lateral spinothalamic tract (pain and temperature sensation) project axons via the dorsolateral tract of Lissauer to secondorder neurons in the substantia gelatinosa of the dorsal horn . Second-order neurons then decussate in the ventral white commissure, ascend in the ventral half of the lateral funiculus, and synapse in the VPL nucleus of the thalamus. Third-order neurons from the thalamus are then relayed to the somatosensory cortex of the postcentral gyrus (areas 3, 1 , and 2) through the posterior limb of the internal capsule. A number of collateral fibers from the spinothalamic tract are relayed to the reticular formation (spinoreticulothalamic tract), which transmits nociceptive fibers to the intralaminar nuclei of the thalamus. Additional fibers of the anterolateral system terminate in either the periaqueductal gray (spinamesencephalic) or the deep layers of the superior colliculus (spinotectal). The periaqueductal gray sends descending projections to serotonergic neurons of the raphe nucleus of the pons and nucleus gigantocellularis (noradrenergic neurons) of the medulla. Both of these areas, in turn , send projections to the dorsal horn and inhibit postsynaptic responses to nociceptive input. The spinotectal pathway directs visual attention to areas of the body that experience intense somatosensory input. Other pathways, such as the dorsal spinocerebellar (K) and ventral spinocerebellar tracts (J), transmit unconscious proprioception from the lower limbs and inferior half of the body to the cerebellum, while the cuneocerebellar and rostrocerebellar tracts com•ey similar information from the upper body and limbs (not shown ) . The corticospinal tract arises predominately from three cortical areas (approximately 30% each): the premotor cortex (area 6), the precentral motor cortex (area 4), and the postcentral sensory cortex (areas 3, 1, and 2). It undergoes a 90% decussation in the caudal medulla and travels in the dorsal quadrant of the lateral funiculus of the spinal cord. The ventral corticospinal tract (H) is a small, uncrossed tract that decussates in the ventral white commissure and is mainly concerned with control of axial musculature. The vestibulospinal tract (F) arises from the lateral vestibular nucleus (Dieter's) and influences extensor tone. The medial longitudinal fasciculus (G) carries fibers from medial and inferior vestibular nuclei, tectospinal tract, and interstitial nucleus of Cajal and coordinates eye movements, mediates nystagmus, and helps control conjugate gaze (Carpenter, pp. 83-106; Pritchard , pp. 114-125; Brazis, pp. 80-85; DeMyer, pp. 120- 132 ) .

Answer 57

B. Facial nerve displacement by an acoustic neuroma is most commonly (in decreasing order of frequency) anterior, followed by superior, inferior, and posterior. The facial nerve is often stretched during microdissection and is most susceptible to injury at the proximal rim of the porus acusticus (Connolly, p. 475).

Answer 58

C. Paralysis of pelvic floor muscles, early sphincter and bladder dysfunction, symmetric saddle anesthesia, impaired erection and ejaculation , constipation, and minimal pain best characterize the conus medullaris syndrome. A tethered cord may present with a combination of neurologic, urologic, orthopedic, and dermatologic manifestations. Commonly patients present with numb feet, muscle atrophy, upper motor neuron signs, bowel and bladder dysfunction, foot deformities, scoliosis, and cutaneous stigmata of spinal dysraphism. Compression of the lumbar and sacral roots below L3 often results in cauda equina syndrome, which is characterized by early pain, asymmetric saddle anesthesia, and a variable patellar reflex response. Sphincter changes are often similar to those of the conus medullaris syndrome but tend to occur late in the clinical course. With S 1 lesions, there is weakness of the triceps surae, flexor digitorum longus (FDL), flexor hallucis longus (FI-lL) , and small foot muscles. The Achilles reflexes are absent, whereas the patellar reflexes are preserved. There is complete sensory loss over the sole, heel, and outer part of the foot and ankle . The gastrocnemius and soleus muscles are stronger with S2 segmental lesions, however, the FDL, FI-lL, and foot muscles remain weak. The sensory loss tends to involve the upper part of the dorsal calf, dorsolateral thigh, and the saddle area (Brazis, pp. 99- 100) .

Answer 59

D. This CT demonstrates a subarachnoid hemorrhage (SAI-l), which is most commonly seen after trauma. Althoughthe blood pattern may vary, traumatic SAH often involves the convexities of the cerebral hemispheres, while aneurysmal subarachnoid hemorrhages generally have a preponderance of blood in the basal cisterns (Greenberg, p. 754).

Answer 60

D. Experimental studies indicate the orbitofrontal cortex is a key region involved with the conscious perception of smell, as lesions in this region have been shown to result in failure to discriminate between various odorants ( Kandel, p. 633) .

Answer 61

D This T2-weighted image shows the hyperintense and thickened folia in a characteristic laminated pattern that is most consistent with Lhermitte-Duclos disease. It is associated with hypertrophy of granular cell neurons and axonal hypermyelination in the molecular layer (Osborn DN, pp. 69-70) .

Answer 62

C This T2-weighted image shows the hyperintense and thickened folia in a characteristic laminated pattern that is most consistent with Lhermitte-Duclos disease. It is associated with hypertrophy of granular cell neurons and axonal hypermyelination in the molecular layer (Osborn DN, pp. 69-70) .

Answer 63

D . This T2-weighted MRI shows a right temporal lobe mass with signal loss (flow void), which is most consistent with a large middle cerebral artery aneurysm (Osborn DN, pp. 266-268).

Answer 64

C (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 65

G (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 66

I (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 67

E (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 68

H (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 69

B (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 70

A (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 71

J (Brazis, pp. 221- 232; Wi lkins, pp. 118-125).

Answer 72

A. Orbital injuries often impair the action of the superior oblique muscle because of displacement of the trochlea, which attaches to the anterior rim of the orbit and acts as a sling for the recurrent course of the trochlear tendon. Looking down and to the left typically involves the right superior oblique (trochlear nerve, IV) and left inferior rectus (oculomotor nerve, III) muscles. •when the eyes look conjugately toward any object, the muscle that is the prime moverworks in unison with the muscle of the opposite eye (Kline, pp. 105-114) .

Answer 73

E. Note the numerous capillaries and cells with a vacuolated appearance in this. photomicrograph depicting a hemangioblastoma. This tumor is associated with VHL in about 25% of cases, is carried in an autosomal dominant fashion (chromosome 3p25), and is associated with retinal angioma, renal cell carcinoma, renal and pancreatic cysts, pheochromocytoma, or epididymal papillary cystadenoma. This tumor may cause polycythemia in about 1 0% of cases due to inappropriate production of erythropoietin (Ellison , pp. 736- 738) .

Answer 74

B Acute hemolytic transfusion reactions are uncommon and are rarely life-threatening. They are produced by antibodies in the recipient that bind to ABO surface antigens or erythrocytes of mismatched do

Answer 75

D Acute hemolytic transfusion reactions are uncommon and are rarely life-threatening. They are produced by antibodies in the recipient that bind to ABO surface antigens or erythrocytes of mismatched do

Answer 76

E. The presence of multiple intradural spinal cord tumors is relatively common with NF-2 and may include ependymomas (most common), schwannomas, and meningiomas (Greenberg, p . 478).

Answer 77

A. The pyramidal neurons of the hippocampus (Ammon's horn) send numerous fiber projections to the subiculum and entorhinal cortex (area 28), which form the anterior part of the parahippocampal gyrus (Carpenter, pp. 369-382)

Answer 78

A. Note the "staghorn" vascular channel in this grade II hemangiopericytoma. These tumors are vimentin-positive, EMA-negative, have a dense arrangement of sheet-like cells, and have a high nuclear-cytoplasmic ratio. Other characteristics include focal lobularity, paucicellular areas, and dense pericellular reticulin (Ell ison, pp. 736-738).

Answer 79

C. Lesions that occupy the anterior part of the left parasylvian fissure may cause a nonfluent type of aphasia (Broca's). This region may abut the parts of the motor cortex that supply • the upper motor neuron fibers for the contralateral facial nucleus. Therefore a patient with right-sided upper motor neuron facial deficit may also have an expressive-type of aphasia originating from Broca's area (Brazis, pp. 511-5 16)

Answer 80

B. A coronal section through the genu of the internal capsule would almost exclusively bisect the globus pallidus, which is triangle-shaped, with its apex fitting into the genu of the internal capsule (Carpenter, pp. 33 7-344 ) .

Answer 81

C. The middle cerebral artery (l'dCA) is divided anatomically into four major segments:

Answer 82

C. Most patients develop some degree of vessel narrowing after aneurysmal subarachnoid hemorrhage. About 70% will develop angiographic vasospasm, and approximately 30% will go on to develop symptomatic vasospasm (Youmans, p. 1545).

Answer 83

E. Over the past few decades a variety of medical, surgical, and radiation interventions have evolved that have proven effective in reducing GH levels. No one treatment is uniformly effective, and often a combination of interventions is required. When a macroadenoma is surgically resected transsphenoidally, endocrine remission rates vary between 65 and 90%. When a macroadenoma is resected, immediate postoperative remission is reported to be even lower (30 and 79%) . The rate of remission is adversely affected by a higher preoperative GH level and larger invasive tumors. Therefore biochemical cure with surgery for large GH-secreting macroadenomas is typically not expected. Conventional radiation therapy can usually shrink pituitary tumors when up to 50 Gy is delivered in 1 . 8-Gy fractions over 6 weeks, but a decrease or normalization of GH levels usually takes many years. 'When initial GH levels are \> 100 f!g/mL, only 60% of patients will attain GH levels

Answer 84

A Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 85

D Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 86

G Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 87

B Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 88

F Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 89

C Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 90

E Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 91

H Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 92

I Figure 8. 108-8 . 1 16Q demonstrates the surgical anatomy of the right lateral and anterior third ventricle during endoscopic third ventriculostomy for aqueductal stenosis. The ventriculostomy site is depicted in the floor of the third ventricle in this figure. The veins of the third ventricular system collect into deeper veins that course in a subependymal location as they travel through the margins of the choroidal fissure to empty into the internal cerebral, basal, and great veins. In general, the veins draining the frontal horn and body of the third ventricle drain into the internal cerebral vein (not depicted here) as it courses through the velum interpositum; those draining the temporal horn drain into a segment of the basal vein of Rosenthal coursing through the ambient cistern; and the veins from the atrium drain into segments of the basal, internal cerebral, and great veins coursing through the quadrigeminal cistern. Of note, the thalamostriate vein passes forward in the sulcus between the caudate nucleus and thalamus toward the foramen of Monro (FOM), where it turns sharply posterior to enter the velum interpositum to join the internal cerebral vein. The angle formed by the junction of the internal cerebral vein and thalamostriate vein, referred to as the venous angle, approximates the level of the FOM on the lateral view of a cerebral angiogram (Wil ki ns, pp. 1427-1429; Youmans, pp. 1237 - 1240 ) .

Answer 93

E . Occlusion or injury of the thalamostriate vein may cause drowsiness, hemiplegia, mutism, and hemorrhagic infarction of the basal ganglia (Wilkins, pp. 1427-1429) .

Answer 94

C. Acute microscopic changes after DAI typically include axonal retraction balls and perivascular hemorrhages, while in later stages there can be astrogliosis, endothelial proliferation, and accumulation of hemosiderin-laden macrophages (Marion, pp. 40-45; Ellison, pp. 249 - 2 5 7 ; Ramsey, pp. 431- 434)

Answer 95

C. In approaching the posterior ilium during autogenous iliac bone graft harvesting, a limited incision that stays within 8 em of the posterior superior iliac spine typically avoids the superior cluneal nerves. Dissection is then carried down to the gluteal fascia, which should be opened directly above the iliac crest to facilitate fascial closure. During subcrestal exposure, the lateral subperiosteal dissection should be carried to the gluteus medius and tensor fascia lata muscles. Subperiosteal dissection usually avoids damage to the superior gluteal artery, which courses through the musculature. The sciatic notch usually lies approximately 7 to 8 em below the iliac crest and must not be violated, as it harbors the main trunk of the sciatic artery, the sciatic nerve, and the CHAPTER 8 Multidisciplinary Self-Assessment Answers 273 ureter, which runs ventral to the superior gluteal artery. Medially, the dissection should extend to the iliacus muscle, which prevents injury to the iliohypogastric and ilioinguinal nerves (Connolly, pp. 819-820).

Answer 96

D Not the absence of the corpus callosum and the high-riding third ventricle on this sagittal MRI depicting agenesis of the corpus callosum. This condition is usually not associated with Chiari I malformation but rather with the Chiari II malformation (Osborn DN, pp. 29-33) .

Answer 97

D Not the absence of the corpus callosum and the high-riding third ventricle on this sagittal MRI depicting agenesis of the corpus callosum. This condition is usually not associated with Chiari I malformation but rather with the Chiari II malformation (Osborn DN, pp. 29-33) .

Answer 98

B Not the absence of the corpus callosum and the high-riding third ventricle on this sagittal MRI depicting agenesis of the corpus callosum. This condition is usually not associated with Chiari I malformation but rather with the Chiari II malformation (Osborn DN, pp. 29-33) .

Answer 99

B. Stability at the atlantoaxial unit is mainly provided by the horizontal portion of the cruciate ligament (transverse atlanta! ligament), and the paired alar lig

Answer 100

C This patient harbors a glomus jugulare tumor, which often presents with unilateral hearing loss or pulsatile tinnitus. I ntracranial extension usually affects multiple cranial nerves, which may result in a number of clinical problems including dysphagia. Angiography is essential because it helps with surgical planning. It helps delineate the blood supply to the tumor as well as collateral blood flow to the brain. Often preoperative embolization is a useful adjunct for these highly vascular and locally invasive tumors. Although observation with serial imaging studies to determine tumor progression may be an appropriate option for medically frail patients, gross total resection is considered the treatment of choice for symptomatic lesions (Youmans, pp. 1295-1308)

Answer 101

D This patient harbors a glomus jugulare tumor, which often presents with unilateral hearing loss or pulsatile tinnitus. I ntracranial extension usually affects multiple cranial nerves, which may result in a number of clinical problems including dysphagia. Angiography is essential because it helps with surgical planning. It helps delineate the blood supply to the tumor as well as collateral blood flow to the brain. Often preoperative embolization is a useful adjunct for these highly vascular and locally invasive tumors. Although observation with serial imaging studies to determine tumor progression may be an appropriate option for medically frail patients, gross total resection is considered the treatment of choice for symptomatic lesions (Youmans, pp. 1295-1308)

Answer 102

A The fracture-pattern (Jefferson fracture) depicted on this axial CT scan most often results from an axial load on a neutral neck. These patients are usually neurologically intact due to the large diameter of the spinal canal at this level. If the sum of. overhang of both lateral masses on C2 is 7 mm, the transYerse ligament js probably disrupted, which requires rigid immobilization (usually with a halo vest) or surgical fi..xation if additional fractures are present (Greenberg, pp. 702-703 )

Answer 103

D The fracture-pattern (Jefferson fracture) depicted on this axial CT scan most often results from an axial load on a neutral neck. These patients are usually neurologically intact due to the large diameter of the spinal canal at this level. If the sum of. overhang of both lateral masses on C2 is 7 mm, the transYerse ligament js probably disrupted, which requires rigid immobilization (usually with a halo vest) or surgical fi..xation if additional fractures are present (Greenberg, pp. 702-703 )

Answer 104

E A lesion o f the facial nerve distal t o the geniculate ganglion but proximal to the stylomastoid foramen typically results in complete paralysis of all ipsilateral facialmuscles, a diminished corneal reflex (with preserved corneal sensation, CN V), impaired sublingual and submandibular salivary gland secretions, hyperacusis, and frequently loss of taste in the anterior two-thirds of the tongue ipsilaterally. Hyperacusis results from paralysis of the stapedius muscle, while salivary secretions are impaired due to the interruption of preganglionic parasympathetic fibers. Lesions proximal to the geniculate ganglion produce all of the disturbances described above and invariably loss of taste in the anterior two-thirds of the tongue and decreased lacrimation. This lesion interrupts all SVA fibers that course centrally and all preganglionic (GVE) fibers as they pass to the pterygopalatine and submandibular ganglia. Taste is permanently lost and no regeneration of sensory fibers takes place. Preganglionic parasympathetic fibers may regenerate, but this may occur in an aberrant fashion. Fibers that previously projected to the submandibular ganglion may regrow and enter the greater petrosal nerve, which may result in lacrimation after a salivary stimulus ("crocodile tears") (Carpenter, pp. 1 72-173)

Answer 105

A A lesion o f the facial nerve distal t o the geniculate ganglion but proximal to the stylomastoid foramen typically results in complete paralysis of all ipsilateral facialmuscles, a diminished corneal reflex (with preserved corneal sensation, CN V), impaired sublingual and submandibular salivary gland secretions, hyperacusis, and frequently loss of taste in the anterior two-thirds of the tongue ipsilaterally. Hyperacusis results from paralysis of the stapedius muscle, while salivary secretions are impaired due to the interruption of preganglionic parasympathetic fibers. Lesions proximal to the geniculate ganglion produce all of the disturbances described above and invariably loss of taste in the anterior two-thirds of the tongue and decreased lacrimation. This lesion interrupts all SVA fibers that course centrally and all preganglionic (GVE) fibers as they pass to the pterygopalatine and submandibular ganglia. Taste is permanently lost and no regeneration of sensory fibers takes place. Preganglionic parasympathetic fibers may regenerate, but this may occur in an aberrant fashion. Fibers that previously projected to the submandibular ganglion may regrow and enter the greater petrosal nerve, which may result in lacrimation after a salivary stimulus ("crocodile tears") (Carpenter, pp. 1 72-173)

Answer 106

B. Mammillary fibers projecting from the medial mammillary nucleus and, to a lesser extent, intermediate and lateral mammillary nuclei form a fiber bundle called the fasciculus mammillaris princes, which divides into two components: the mammillothalamic tract and mammillotegmental tract. The mammillothalamic tract contains fibers that originate from the .medial mammillary nucleus and project to the anterior thalamic nucleus. Fibers from the hippocampus are also superimposed on this fiber bundle as they travel to the anterior thalamic nucleus through the fornix. The mammillotegmental tract terminates in the dorsal and ventral tegmental nuclei (Carpenter, p. 309)

Answer 107

B. Crossed fibers from the fastigial nucleus emerge from the cerebellum through the uncinate fasciculus of Russell, which arches . around the superior cerebellar peduncle. Uncrossed fastigial efferents project to the brainstem in the juxtarestiform body. The largest number of fastigial efferents project to structures in the lower brainstem (nucleus reticularis gigantocellularis, central pontine reticular formation, dorsal paramedian reticular nucleus). A small number of fibers ascend in the dorsolateral brainstem and send collaterals to the superior colliculus and nuclei of the posterior commissure prior to terminating in various thalamic regions (VLc and VPLo) (Carpenter, pp. 241-243 )

Answer 108

A . Some excitatory effects o f the sympathetic nervous system that lack parasympathetic opposition include

Answer 109

A The mechanism of most modern hangman's fractures results from hyperextension and axial loading (diving and motor vehicle accidents), while judicial hangings often resulted in hyperextension and distractive forces from submeatal knot placement. Patients rarely require surgical intervention for this type of fracture, which is typically reserved for irreducible fractures, failure of external immobilization, traumatic C2-3 elise herniation (with canal compromise and progressive neurologic deficit), and established nonunion. All fusion techniques typically involve fusing C2 to C3, although the majority of patients can be successfully treated with a cervical collar, SOMI brace, or halo vest (most common) (Greenberg, pp. 704-706) .

Answer 110

D The mechanism of most modern hangman's fractures results from hyperextension and axial loading (diving and motor vehicle accidents), while judicial hangings often resulted in hyperextension and distractive forces from submeatal knot placement. Patients rarely require surgical intervention for this type of fracture, which is typically reserved for irreducible fractures, failure of external immobilization, traumatic C2-3 elise herniation (with canal compromise and progressive neurologic deficit), and established nonunion. All fusion techniques typically involve fusing C2 to C3, although the majority of patients can be successfully treated with a cervical collar, SOMI brace, or halo vest (most common) (Greenberg, pp. 704-706) .

Answer 111

E. Klippel-Feil syndrome ranges from fusion of only a few vertebral bodies to fusion of the entire spine. It results from failure of somite segregation between 3 and 8 weeks' gestation. The classic triad (usually present in

Answer 112

C The anterior fontanelle, the largest fontanelle, is diamond-shaped and normally closes by 2 . 5 years of age. The posterior fontanelle is triangle-shaped and closes by 2 to 3 months. The sphenoid and mastoid fontanelles are smaller, more irregular, and usually close by 2 to 3 months and 1 year, respectively (Greenberg, p. 138).

Answer 113

A The anterior fontanelle, the largest fontanelle, is diamond-shaped and normally closes by 2 . 5 years of age. The posterior fontanelle is triangle-shaped and closes by 2 to 3 months. The sphenoid and mastoid fontanelles are smaller, more irregular, and usually close by 2 to 3 months and 1 year, respectively (Greenberg, p. 138).

Answer 114

A The anterior fontanelle, the largest fontanelle, is diamond-shaped and normally closes by 2 . 5 years of age. The posterior fontanelle is triangle-shaped and closes by 2 to 3 months. The sphenoid and mastoid fontanelles are smaller, more irregular, and usually close by 2 to 3 months and 1 year, respectively (Greenberg, p. 138).

Answer 115

B The anterior fontanelle, the largest fontanelle, is diamond-shaped and normally closes by 2 . 5 years of age. The posterior fontanelle is triangle-shaped and closes by 2 to 3 months. The sphenoid and mastoid fontanelles are smaller, more irregular, and usually close by 2 to 3 months and 1 year, respectively (Greenberg, p. 138).

Answer 116

E. Blood supply to the dura originates from the middle meningeal artery, which is a branch of the maxillary artery. It enters the skull through the foramen spinosum. The ophthalmic artery (anterior meningeal branches) and occipital and vertebral arteries (posterior meningeal arteries) also provide meningeal branches to the dura (Carpenter, pp. 1-2 )

Answer 117

B. The typical order o f the three great vessels that originate from the aortic arch is the brachiocephalic trunk (innominate artery) followed by the left common carotid artery (LCCA) and then left subclavian artery (LSCA). This configuration is fatind in approximately two-thirds of all cases. A shared origin of the brachiocephalic trunk and left common carotid artery is seen in 27% (most frequentvariant) of cases, while in 7% of cases the left common carotid artery arises from the proximal brachiocephalic artery instead of the aortic arch. In 1 to 2% of cases, the LCCA and LSCA share a common origin and form a left-sided brachiocephalic trunk (Osborn DCA, p. 16).

Answer 118

C. Formal diagnosis of myasthenia gravis depends on demonstration of response to cholinergic medications, EMG evidence of abnormal neuromuscular transmission ("jitter," "blocking"), and identification of circulating antibodies to Ach receptors or myofibrillar proteins such as actin, titin, myosin, and actinomycin (in approximately 85 to 90% of cases). In single-muscle-fiber EMG studies, an electrode measures the interval between evoked potentials of muscle fibers in the same unit. This interval normally varies by "jitter", for which the temporal limits have been defined. In myasthenia gravis, "jitter" is increased. If muscle fibers are not activated due to abnormal neuromuscular transmission, it is called "blocking. " Myasthenia gravis is characterized by both "blocking" and increased "jitter," although these findings are not specific for myasthenia gravis, as other disorders may show a similar response on EMG studies. Signs of denervation are almost never seen in disorders of ACh release unless other conditions supervene. Cholinergic medications should be stopped once an endotracheal tube has been placed to reduce the amount of pulmonary secretions. Prednisone, plasmapheresis, and IVIG therapy have all been used in patients with generalized disease and/or respiratorycrisis. Thymectomy is generally recommended for patients with generalized myasthenia gravis, not ocular myasthenia (Merritt, pp. 723 - 726)

Answer 119

G Refer to Table 8. 143- 8. 148A (Merritt, p. 525) .

Answer 120

F Refer to Table 8. 143- 8. 148A (Merritt, p. 525) .

Answer 121

C Refer to Table 8. 143- 8. 148A (Merritt, p. 525) .

Answer 122

E Refer to Table 8. 143- 8. 148A (Merritt, p. 525) .

Answer 123

B Refer to Table 8. 143- 8. 148A (Merritt, p. 525) .

Answer 124

A Refer to Table 8. 143- 8. 148A (Merritt, p. 525) . 149.

Answer 125

B. The largest quantity of afferents projecting to the striatum originate in the cerebral cortex, although the amygdala, intralaminar nuclei of the thalamus, the substantia nigra, and dorsal raphe nucleus send fibers to various parts of the striatum as well (Carpenter, pp. 332 -336).

Answer 126

D Athetoid movements are slow, writhing movements predominately of the hand and wrist, while dystonia characteristically affects the axial muscles. The lesion "status marmoratus" characterizes one form of cerebral palsy, which consists of a "marbled appearance of the corpus striatum and thalamus secondary to perinatal hypoxia. Hypoxic damage i n. these areas results i n overgrowth o f astrocytes a s part o f the healing process. Oligodendrocytes then mistakenly myelinate astrocytic processes, which causes white patches to appear in the nuclei, giving them a marbled appearance. Damage to the striatum and thalamus from other causes such as infarcts may also result in athetosis. Lesions of the substantia nigra can result in rigidity -and resting tremor, which are some of the hallmarks of Parkinson's disease. Lesions of the subthalamicnucleus can produce hemiballism, while terminal tremor, ataxia, and CN III palsy usually result from injury in the vicinity of the red nucleus. Bilateral lesions of the amygdala can produce the Kliiver-Bucy syndrome, which is characterized by visual agnosia, oral-exploratory behavior, hypersexuality, hypomotility, and hypem1etamorphosis (tendency to take notice and attend to every visual stimulus) (Brazis, pp. 433-436, 439-442, 552; Merritt, pp. 681-682)

Answer 127

B Athetoid movements are slow, writhing movements predominately of the hand and wrist, while dystonia characteristically affects the axial muscles. The lesion "status marmoratus" characterizes one form of cerebral palsy, which consists of a "marbled appearance of the corpus striatum and thalamus secondary to perinatal hypoxia. Hypoxic damage i n. these areas results i n overgrowth o f astrocytes a s part o f the healing process. Oligodendrocytes then mistakenly myelinate astrocytic processes, which causes white patches to appear in the nuclei, giving them a marbled appearance. Damage to the striatum and thalamus from other causes such as infarcts may also result in athetosis. Lesions of the substantia nigra can result in rigidity -and resting tremor, which are some of the hallmarks of Parkinson's disease. Lesions of the subthalamicnucleus can produce hemiballism, while terminal tremor, ataxia, and CN III palsy usually result from injury in the vicinity of the red nucleus. Bilateral lesions of the amygdala can produce the Kliiver-Bucy syndrome, which is characterized by visual agnosia, oral-exploratory behavior, hypersexuality, hypomotility, and hypem1etamorphosis (tendency to take notice and attend to every visual stimulus) (Brazis, pp. 433-436, 439-442, 552; Merritt, pp. 681-682)

Answer 128

C Athetoid movements are slow, writhing movements predominately of the hand and wrist, while dystonia characteristically affects the axial muscles. The lesion "status marmoratus" characterizes one form of cerebral palsy, which consists of a "marbled appearance of the corpus striatum and thalamus secondary to perinatal hypoxia. Hypoxic damage i n. these areas results i n overgrowth o f astrocytes a s part o f the healing process. Oligodendrocytes then mistakenly myelinate astrocytic processes, which causes white patches to appear in the nuclei, giving them a marbled appearance. Damage to the striatum and thalamus from other causes such as infarcts may also result in athetosis. Lesions of the substantia nigra can result in rigidity -and resting tremor, which are some of the hallmarks of Parkinson's disease. Lesions of the subthalamicnucleus can produce hemiballism, while terminal tremor, ataxia, and CN III palsy usually result from injury in the vicinity of the red nucleus. Bilateral lesions of the amygdala can produce the Kliiver-Bucy syndrome, which is characterized by visual agnosia, oral-exploratory behavior, hypersexuality, hypomotility, and hypem1etamorphosis (tendency to take notice and attend to every visual stimulus) (Brazis, pp. 433-436, 439-442, 552; Merritt, pp. 681-682)

Answer 129

A Athetoid movements are slow, writhing movements predominately of the hand and wrist, while dystonia characteristically affects the axial muscles. The lesion "status marmoratus" characterizes one form of cerebral palsy, which consists of a "marbled appearance of the corpus striatum and thalamus secondary to perinatal hypoxia. Hypoxic damage i n. these areas results i n overgrowth o f astrocytes a s part o f the healing process. Oligodendrocytes then mistakenly myelinate astrocytic processes, which causes white patches to appear in the nuclei, giving them a marbled appearance. Damage to the striatum and thalamus from other causes such as infarcts may also result in athetosis. Lesions of the substantia nigra can result in rigidity -and resting tremor, which are some of the hallmarks of Parkinson's disease. Lesions of the subthalamicnucleus can produce hemiballism, while terminal tremor, ataxia, and CN III palsy usually result from injury in the vicinity of the red nucleus. Bilateral lesions of the amygdala can produce the Kliiver-Bucy syndrome, which is characterized by visual agnosia, oral-exploratory behavior, hypersexuality, hypomotility, and hypem1etamorphosis (tendency to take notice and attend to every visual stimulus) (Brazis, pp. 433-436, 439-442, 552; Merritt, pp. 681-682)

Answer 130

E Athetoid movements are slow, writhing movements predominately of the hand and wrist, while dystonia characteristically affects the axial muscles. The lesion "status marmoratus" characterizes one form of cerebral palsy, which consists of a "marbled appearance of the corpus striatum and thalamus secondary to perinatal hypoxia. Hypoxic damage i n. these areas results i n overgrowth o f astrocytes a s part o f the healing process. Oligodendrocytes then mistakenly myelinate astrocytic processes, which causes white patches to appear in the nuclei, giving them a marbled appearance. Damage to the striatum and thalamus from other causes such as infarcts may also result in athetosis. Lesions of the substantia nigra can result in rigidity -and resting tremor, which are some of the hallmarks of Parkinson's disease. Lesions of the subthalamicnucleus can produce hemiballism, while terminal tremor, ataxia, and CN III palsy usually result from injury in the vicinity of the red nucleus. Bilateral lesions of the amygdala can produce the Kliiver-Bucy syndrome, which is characterized by visual agnosia, oral-exploratory behavior, hypersexuality, hypomotility, and hypem1etamorphosis (tendency to take notice and attend to every visual stimulus) (Brazis, pp. 433-436, 439-442, 552; Merritt, pp. 681-682)

Answer 131

E. The thalamus receives its arterial supply from the anterior choroidal artery ( ICA) and thalamoperforating arteries (PComA and basilar artery) as well as the thalamogeniculate and posterior choroidal arteries (PCA). Infarctions may occur in each of these thalamic territories and cause various clinical syndromes, depending on which thalamic nuclei are involved (Carpenter, pp. 441- 450).

Answer 132

B. Note the prominent diffuse plaques traversed by neuronal processes in this patient with Alzheimer's disease. Diffuse amyloid plaques are extracellular, ill-defined focal aggregates of amyloid and preamyloid material and are approximately 60 to 300 mm in diameter. Neuronal cell processes traversing the plaque typically appear normal and do not contain tau protein ( Ell ison, pp. 553-557)

Answer 133

E. Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 134

D Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 135

A Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 136

F Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 137

H Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 138

E Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 139

A Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 140

G Occipital condylar and burst fractures are often the result of purely axial compressive forces on a neutral neck, while teardrop and compression-wedge fractures result from compressive force on a flexed neck. Other injury or fracture patterns in the cervical spine include unilateral (axial rotation, flexing) and bilateral locked (hyperflexion and distraction) facets, Chance fracture (flexion, distraction), and unila teral facet fracture (lateral bending, compression) . Odontoid fractures usually result from hyperflexion injuries and result in anterior displacement of C2 on C3. (Greenberg, pp. 702- 7 14; Youmans, pp. 517-523, 4896-4897 , 4927 ; Harris, pp. 69- 91)

Answer 141

C. Note the squamous cells. peripheral palisading of nuclei, and nodules of wet keratin in this adamantinomatous craniopharyngioma (Ellison, pp. 724-72 7 ; WHO, pp. 244- 246).

Answer 142

E. Approximately 90% of cases of vertigo are likely secondary to lesions of the vestibular end organs or vestibular nerves, while the rest usually originate from the central nervous system, including craniocervical junction abnormalities (Merritt, pp. 28-30). .

Answer 143

D. The supratentorial dura is innervated primarily by branches of the trigeminal nen•E. while the infratentorial dura is innervated by branches of the vagus and lower cervical spinal nerves ( Carpenter, p. 2 )

Answer 144

D Depicted here is an axial a n d parasagittal MRI showing a soft (mainly disc material) posterolateral disc herniation of the cervical spine that is eccentric to the left. Considering that this disc herniation is not purely central, i t may b e amenable to a posterolateral procedure in a n attempt to preserve vocal cord function (posterior keyhole laminotomy) in this wedding singer. Over 90% of patients with acute cervical radiculopathy will improve with nonsurgical therapy including adequate pain medication and antiinflammatories. Surgery is indicated for those who fail to improve or develop progressive neurologic deficits while undergoing nonsurgical therapy. A number of large series have reported good or excellent results in 90 to 96% of patients who underwent a posterior approach for such disc herniations (Greenberg, pp. 3 10-314).

Answer 145

C Depicted here is an axial a n d parasagittal MRI showing a soft (mainly disc material) posterolateral disc herniation of the cervical spine that is eccentric to the left. Considering that this disc herniation is not purely central, i t may b e amenable to a posterolateral procedure in a n attempt to preserve vocal cord function (posterior keyhole laminotomy) in this wedding singer. Over 90% of patients with acute cervical radiculopathy will improve with nonsurgical therapy including adequate pain medication and antiinflammatories. Surgery is indicated for those who fail to improve or develop progressive neurologic deficits while undergoing nonsurgical therapy. A number of large series have reported good or excellent results in 90 to 96% of patients who underwent a posterior approach for such disc herniations (Greenberg, pp. 3 10-314).

Answer 146

B. Yolk sac tumor is a germ cell tumor that exhibits loosely arranged cells with clear cytoplasm and prominent eosinophilic bodies. Yolk sac tumors are positive for AFP, and they often exhibit Schiller-Duval bodies ( Ellison, p. 683).

Answer 147

B. Meticulous preoperative anesthetic workup is extremely important for acromegalic patients, since they frequently exhibit cardiomyopathy and macroglossia , which can be associated with a difficult airway (Youmans, p. 569)

Answer 148

C. HD primarily affects the GABA/enkephalin projections from the striatum to the external segment of the globus pallidus (indirect pathway), resulting in thalamic facilitation of motor cortical areas and hyperkinesia (Merritt, pp. 659- 662 )

Answer 149

E . Note the prominent lobules o f cells with a n intervening vascular network of sinusoids in this photomicrograph of a normal adenohypophysis ( Ellison, p. 716)

Answer 150

C. Meckel-Gruber syndrome typically includes encephalocele, microcephaly, microphthalmia, cleft lip, polydactyly, polycystic kidneys, congenital heart disease, and ambiguous genitalia; it is most often associated with maternal hyperthermia on gestational days 20 to 26 ( Rudolph, p. 156)

Answer 151

D. The release of a single quantum of acetylcholine ( 10,000 molecules of ACh) produces a miniature endplate potential (MEPP) in the postsynaptic membrane, which is not significant enough to generate an action potential. The summation of several quanta is required to induce enough depolarization in the postsynaptic cell membrane to result in an action potential ( Kandel, pp. 255-262)

Answer 152

B. Nitric oxide (NO) is produced in neurons by the Ca2+/calmodulin-dependent enzyme NO synthasE. NO, in turn, stimulates the synthesis of cGMP through the action of guanylyl cyclase, an enzyme that converts GTP to cGMP. NO • acts locally and is primarily released from endothelial cells to induce smooth muscle relaxation and blood vessel dilation (Kandel, p. 239)

Answer 153

C. Neuronal cytoplasmic organelles include rough and smooth endoplasmic reticulum, endosomes, secretory vesicles, lysosomes, peroxisomes, mitochondria, and the Golgi apparatus. Proteins and phospholipids destined for secretion are initially synthesized in the rough endoplasmic reticulum (rER). These products are then transported to the Golgi apparatus via transport vesicles for processing (although N-linked glycosylation and glycolipid conjugation are initiated in the rER) . The Golgi complex further modifies these proteins by adding polysaccharides, which can direct specific proteins to secretory vesicles, lysosomes, and the plasma membranE. Golgi processing includes glycosylation reactions (0-linked and N-linked glycosylation), proteoglycan formation, polysaccharide phosphorylation, attachment of fatty acids, and sulfation of tyrosine (not arginine) and sugar residues. This processing increases the hydrophilicity (solubility) of these proteins, increases their biological activity, or helps delay their degradation by proteases. Clathrin coats facilitate the budding of vesicles from the Golgi complex. Secretory vesicles (dense-core vesicles) are targeted primarily to axon terminals, where they participate in calciumregulated exocytosis after action potential propagation (Kandel, pp. 67-7 1, 94-9 7)

Answer 154

B. The EBB is primarily composed of tight junctions between nonfenestrated endothelial cells. These endothelial cells are also deficient in vesicular transport compared to endothelial cells elsewhere in the body, which further contributes to the selectivity of the EBB. The resistance provided by the tight junctions between endothelial cells in the brain is extremely high. Substances may cross the EBB by diffusion, active transport, carrier-mediated transport, and through ion channels. Lipid-soluble substances readily diffuse across endothelial cell membranes i n to the brain; hence the permeability of many substances is directly related to their lipid-solubility. Specific carrier-mediated transport is responsible for the entry of most substances into the brain. The glucose transporter (Glut1) is energy-independent, thus transporting only glucose down its concentration gradient from the bloodstream into the brain. There are also three distinct carrier systems for amino acid transport across the EBB. The L system transports large neutral branched-chain amino acids and L-DOPA into the brain. A transport system that is a member of the multiple-drug-resistance (MDR) transporter family found i n tumor cells removes a wide range of hydrophobic toxins and chemotherapeutic agents from the brain. Additionally, specific ion channels allow the movement of electrolytes across the BBB. A metabolic BBB also exists due to the presence of certain enzymes that rapidly metabolize substances as they enter the CNS. An example is the high concentration of DOPA decarboxylase i n epithelial cells that rapidly metabolize L-DOPA as it enters the brain CHAPTER 8 Multidisciplinary Self-Assessment Answers 2 77 unless a DOPA decarboxylase inhibitor (carbidopa) is also administered (Kandel, pp. 1288-1294).

Answer 155

D. The substantia nigra has the highest concentration of substance P in the brain. Striatonigral projections from the caudate nucleus and putamen contain GABA, substance P, and enkephalin (Carpenter, pp. 2 15.-221)

Answer 156

C. Note that the anterior cerebral arteries are being pushed upward on this lateral angiogram, depicting an olfactory groove meningiomA. These lesions often grow insidiously, causing gradual compression of the frontal lobes; thus they are quite large and bilateral by the time of presentation. Common signs/symptoms may include headaches, personality changes, visual loss, anosmia, and seizures. A bifrontal transbasal approach is frequently used in resecting these tumors, although a unilateral subfrontal or frontotemporal (pterional) craniotomy can also be useD. The anterior and posterior ethmoid arteries typically supply olfactory groove meningiomas (Kaye and Black, pp. 523 -532 ; Youmans, pp. 1115-1115)

Answer 157

E. Note that the anterior cerebral arteries are being pushed upward on this lateral angiogram, depicting an olfactory groove meningiomA. These lesions often grow insidiously, causing gradual compression of the frontal lobes; thus they are quite large and bilateral by the time of presentation. Common signs/symptoms may include headaches, personality changes, visual loss, anosmia, and seizures. A bifrontal transbasal approach is frequently used in resecting these tumors, although a unilateral subfrontal or frontotemporal (pterional) craniotomy can also be useD. The anterior and posterior ethmoid arteries typically supply olfactory groove meningiomas (Kaye and Black, pp. 523 -532 ; Youmans, pp. 1115-1115)

Answer 158

A Charcot-Marie-Tooth (GMT) disease, or peroneal muscular atrophy, accounts for about 90% of all hereditary neuropathies, of which there are three types. CMT-1 , the most common, is autosomal dominant and is a demyelinating disease that results in a distal sensorimotor neuropathy. It results from mutations in peripheral myelin protein 22 (PMP-22), exhibits slowed nerve conduction velocities, and exhibits onion-bulb formations on histopathologic studies. CMT-2 resembles CMT-1 but results in axonal degeneration instead of demyelination. GMT-3, also known as Dejerine-Sottas syndrome, is autosomal dominant and results in a hypertrophic demyelinating neuropathy. DMD is an X-li nked recessive condition that results from mutation of the dystrophin gene, located at Xp2 1 . Patients often have difficulty rising from the ground and rely heavily on the arms to raise the torso and legs (Gowers' sign ) . These patients may also exhibit toe-walking and develop an exaggerated lumbar lordosis or scoliosis as well as pseudohypertrophy of the calves from fibrosis and fatty infiltration of degenerating muscle MD is a trinucleotide repeat disorder that results from mutation of the dystrophia myotonica protein kinase gene on chromosome 1 9 . It is a pleiotropic, autosomal dominant disorder affecting the skeletal muscle, heart, eyes, and exocrine glands. The myopathy of MD affects se\'eral cranial nerves (ptosis, dysarthria, dysphagia) and the distal extremities (finger flexors and extensors) . Patients exhibit myotonia (impaired muscle relaxation), cataracts, frontal balding, testicular atrophy, retinal degeneration, cardiomyopathy, and an increased incidence of mental retardation. FSHMD is an autosomal dominant disorder that results in scapular winging, facial weakness, shoulder girdle weakness, and lower extremity weakness (Merritt, pp. 737-7 46)

Answer 159

B Charcot-Marie-Tooth (GMT) disease, or peroneal muscular atrophy, accounts for about 90% of all hereditary neuropathies, of which there are three types. CMT-1 , the most common, is autosomal dominant and is a demyelinating disease that results in a distal sensorimotor neuropathy. It results from mutations in peripheral myelin protein 22 (PMP-22), exhibits slowed nerve conduction velocities, and exhibits onion-bulb formations on histopathologic studies. CMT-2 resembles CMT-1 but results in axonal degeneration instead of demyelination. GMT-3, also known as Dejerine-Sottas syndrome, is autosomal dominant and results in a hypertrophic demyelinating neuropathy. DMD is an X-li nked recessive condition that results from mutation of the dystrophin gene, located at Xp2 1 . Patients often have difficulty rising from the ground and rely heavily on the arms to raise the torso and legs (Gowers' sign ) . These patients may also exhibit toe-walking and develop an exaggerated lumbar lordosis or scoliosis as well as pseudohypertrophy of the calves from fibrosis and fatty infiltration of degenerating muscle MD is a trinucleotide repeat disorder that results from mutation of the dystrophia myotonica protein kinase gene on chromosome 1 9 . It is a pleiotropic, autosomal dominant disorder affecting the skeletal muscle, heart, eyes, and exocrine glands. The myopathy of MD affects se\'eral cranial nerves (ptosis, dysarthria, dysphagia) and the distal extremities (finger flexors and extensors) . Patients exhibit myotonia (impaired muscle relaxation), cataracts, frontal balding, testicular atrophy, retinal degeneration, cardiomyopathy, and an increased incidence of mental retardation. FSHMD is an autosomal dominant disorder that results in scapular winging, facial weakness, shoulder girdle weakness, and lower extremity weakness (Merritt, pp. 737-7 46)

Answer 160

B Charcot-Marie-Tooth (GMT) disease, or peroneal muscular atrophy, accounts for about 90% of all hereditary neuropathies, of which there are three types. CMT-1 , the most common, is autosomal dominant and is a demyelinating disease that results in a distal sensorimotor neuropathy. It results from mutations in peripheral myelin protein 22 (PMP-22), exhibits slowed nerve conduction velocities, and exhibits onion-bulb formations on histopathologic studies. CMT-2 resembles CMT-1 but results in axonal degeneration instead of demyelination. GMT-3, also known as Dejerine-Sottas syndrome, is autosomal dominant and results in a hypertrophic demyelinating neuropathy. DMD is an X-li nked recessive condition that results from mutation of the dystrophin gene, located at Xp2 1 . Patients often have difficulty rising from the ground and rely heavily on the arms to raise the torso and legs (Gowers' sign ) . These patients may also exhibit toe-walking and develop an exaggerated lumbar lordosis or scoliosis as well as pseudohypertrophy of the calves from fibrosis and fatty infiltration of degenerating muscle MD is a trinucleotide repeat disorder that results from mutation of the dystrophia myotonica protein kinase gene on chromosome 1 9 . It is a pleiotropic, autosomal dominant disorder affecting the skeletal muscle, heart, eyes, and exocrine glands. The myopathy of MD affects se\'eral cranial nerves (ptosis, dysarthria, dysphagia) and the distal extremities (finger flexors and extensors) . Patients exhibit myotonia (impaired muscle relaxation), cataracts, frontal balding, testicular atrophy, retinal degeneration, cardiomyopathy, and an increased incidence of mental retardation. FSHMD is an autosomal dominant disorder that results in scapular winging, facial weakness, shoulder girdle weakness, and lower extremity weakness (Merritt, pp. 737-7 46)

Answer 161

B Charcot-Marie-Tooth (GMT) disease, or peroneal muscular atrophy, accounts for about 90% of all hereditary neuropathies, of which there are three types. CMT-1 , the most common, is autosomal dominant and is a demyelinating disease that results in a distal sensorimotor neuropathy. It results from mutations in peripheral myelin protein 22 (PMP-22), exhibits slowed nerve conduction velocities, and exhibits onion-bulb formations on histopathologic studies. CMT-2 resembles CMT-1 but results in axonal degeneration instead of demyelination. GMT-3, also known as Dejerine-Sottas syndrome, is autosomal dominant and results in a hypertrophic demyelinating neuropathy. DMD is an X-li nked recessive condition that results from mutation of the dystrophin gene, located at Xp2 1 . Patients often have difficulty rising from the ground and rely heavily on the arms to raise the torso and legs (Gowers' sign ) . These patients may also exhibit toe-walking and develop an exaggerated lumbar lordosis or scoliosis as well as pseudohypertrophy of the calves from fibrosis and fatty infiltration of degenerating muscle MD is a trinucleotide repeat disorder that results from mutation of the dystrophia myotonica protein kinase gene on chromosome 1 9 . It is a pleiotropic, autosomal dominant disorder affecting the skeletal muscle, heart, eyes, and exocrine glands. The myopathy of MD affects se\'eral cranial nerves (ptosis, dysarthria, dysphagia) and the distal extremities (finger flexors and extensors) . Patients exhibit myotonia (impaired muscle relaxation), cataracts, frontal balding, testicular atrophy, retinal degeneration, cardiomyopathy, and an increased incidence of mental retardation. FSHMD is an autosomal dominant disorder that results in scapular winging, facial weakness, shoulder girdle weakness, and lower extremity weakness (Merritt, pp. 737-7 46)

Answer 162

B Charcot-Marie-Tooth (GMT) disease, or peroneal muscular atrophy, accounts for about 90% of all hereditary neuropathies, of which there are three types. CMT-1 , the most common, is autosomal dominant and is a demyelinating disease that results in a distal sensorimotor neuropathy. It results from mutations in peripheral myelin protein 22 (PMP-22), exhibits slowed nerve conduction velocities, and exhibits onion-bulb formations on histopathologic studies. CMT-2 resembles CMT-1 but results in axonal degeneration instead of demyelination. GMT-3, also known as Dejerine-Sottas syndrome, is autosomal dominant and results in a hypertrophic demyelinating neuropathy. DMD is an X-li nked recessive condition that results from mutation of the dystrophin gene, located at Xp2 1 . Patients often have difficulty rising from the ground and rely heavily on the arms to raise the torso and legs (Gowers' sign ) . These patients may also exhibit toe-walking and develop an exaggerated lumbar lordosis or scoliosis as well as pseudohypertrophy of the calves from fibrosis and fatty infiltration of degenerating muscle MD is a trinucleotide repeat disorder that results from mutation of the dystrophia myotonica protein kinase gene on chromosome 1 9 . It is a pleiotropic, autosomal dominant disorder affecting the skeletal muscle, heart, eyes, and exocrine glands. The myopathy of MD affects se\'eral cranial nerves (ptosis, dysarthria, dysphagia) and the distal extremities (finger flexors and extensors) . Patients exhibit myotonia (impaired muscle relaxation), cataracts, frontal balding, testicular atrophy, retinal degeneration, cardiomyopathy, and an increased incidence of mental retardation. FSHMD is an autosomal dominant disorder that results in scapular winging, facial weakness, shoulder girdle weakness, and lower extremity weakness (Merritt, pp. 737-7 46)

Answer 163

E. The common peroneal nerve (L4-S2) innervates the extensors and adductors of the leg (and part of the biceps femoris) and gives rise to the lateral sural cutaneous nerve (to the inferolateral leg), the deep peroneal nerve, and the superficial peroneal nervE. The deep peroneal nerve innervates the tibialis anterior, extensor hallucis longus, and extensor digitorum longus muscles. The superficial peroneal nerve innervates the peroneus longus/brevis (foot eversion) and the skin of the distal anterior leg, dorsum of the foot, and digits. Lesions of the common peroneal nerve mainly result in paralysis of dorsiflexion (footdrop) and foot eversion (Patten, p. 3 1 1 ; G reenberg, pp. 522, 545).

Answer 164

B. Hippocampal sclerosis usually has a very characteristic pattern in patients with mesial temporal lobe epilepsy. The greatest amount of damage is usually seen in the CAl and CA4 sectors, while the least amount of damage occurs in CA2. Synaptic reorganization of granule cell mossy fibers is usually a characteristic feature of hippocampal sclerosis (Committee on Education in Neurological Surgery, pp. 20, 110; Mathern et a l . , pp. 105-113).

Answer 165

C. Nephrocalcinosis frequently accompanies type I, or distal, renal tubular acidosis (RTA). In type 1 RTA, the proximal reabsorption of HCO; is adequate, but the ability of the distal tubule to secrete H+ ions is inadequatE. The urine pH remains above 5 . 5 , and hypokalemia, hypercalcemia, nephrocalcinosis, and osteomalacia frequently accompany this abnormality. Moderate amounts of bicarbonate therapy may correct the acidosis. With type II RTA, the ability of the proximal tubule to reabsorb HCO; is compromised; HCO; is lost in the urine and acidemia develops secondary to the inability of the distal tubule to reabsorb the flood of HCO;. Eventually, the serum HCO; decreases to a point where the proximal renal tubule can reabsorb most of the reduced HCO; load, while the remainder is reclaimed in the distal tubulE. This maintains the urine pH

Answer 166

A This lesion i s most consistent with a DNT (WliO grade I ) . Patients usually present with long-standing drug-resistant partial seizures that begin before the age of 20. They are usually found in the temporal lobe or other supratentorial location and typically encompass the cerebral cortex. On occasion, they appear to deform the overlying calvarium, a finding that further supports the diagnosis of DNT. The histologic hallmark of this tumor is the glioneuronal element, which is shown here to consist of a free-floating neuron in a microcyst surrounded by oligodendroglial-like cells (Ellison, pp. 659-661; WHO, pp. 103-106)

Answer 167

C This lesion i s most consistent with a DNT (WliO grade I ) . Patients usually present with long-standing drug-resistant partial seizures that begin before the age of 20. They are usually found in the temporal lobe or other supratentorial location and typically encompass the cerebral cortex. On occasion, they appear to deform the overlying calvarium, a finding that further supports the diagnosis of DNT. The histologic hallmark of this tumor is the glioneuronal element, which is shown here to consist of a free-floating neuron in a microcyst surrounded by oligodendroglial-like cells (Ellison, pp. 659-661; WHO, pp. 103-106)

Answer 168

B This lesion i s most consistent with a DNT (WliO grade I ) . Patients usually present with long-standing drug-resistant partial seizures that begin before the age of 20. They are usually found in the temporal lobe or other supratentorial location and typically encompass the cerebral cortex. On occasion, they appear to deform the overlying calvarium, a finding that further supports the diagnosis of DNT. The histologic hallmark of this tumor is the glioneuronal element, which is shown here to consist of a free-floating neuron in a microcyst surrounded by oligodendroglial-like cells (Ellison, pp. 659-661; WHO, pp. 103-106)

Answer 169

D. Although the MCV progressively decreases as the anemia becomes more severe, the MCHC usually remains normal until the hematocrit values drop below 30%. As the anemia becomes more marked, the red blood cells become progressively more distorted (poikilocytosis), the TIBC begins to increase, the ferritin levels drop, the serum iron stores begin to fall, and the bone marrow iron stores become depleteD. Causes of anemia with low MCV include iron deficiency (pregnancy, GI bleeding), thalassemia, anemia of chronic inflammation, sideroblastic anemia, and aluminum toxicity ( Fishman, pp. 345-34 7 ; Barker, pp. 620-623)

Answer 170

B . The addition of phenytoin and phenobarbital most often increases the serum concentration of valproate (Geyer, p. 2 13 )

Answer 171

C. IBM affects proximal limb muscles, but in contrast to polymyositis, is much more likely to affect the distal muscles of the legs. It commonly occurs in men after the age of 50 and has less of an association with autoimmune and collagen vascular diseases than polymyositis. Wl1ereas polymyositis does respond to steroids, IBM has no widely accepted therapy, as steroids have shown minimal benefit (Merritt, pp. 767 - 768).

Answer 172

E. Graves' disease (hyperthyroidism) does not typically cause carpal tunnel syndrome but is more likely to produce ophthalmopathy, including a "stare" and "lid lag," and thyroid exophthalmos from inucinous and cellular infiltration of the extraocular muscles (inferior and medial recti most commonly affected) . Common etiologies of carpal tunnel syndrome include rheumatoid arthritis, pregnancy, acromegaly, amyloidosis, myxedema, and birth control pills (Greenberg, pp. 536-539)

Answer 173

C. This constellation of signs/symptoms is most consistent with the lateral medullary syndrome (of Wallenberg) . In a young patient who was subjected to strenuous exercise and extreme neck movements, the most likely diagnosis is vertebral artery dissection (Greenberg, pp. 849-850)

Answer 174

C. EGF and TGF-a bind to EGFR with equal affinity; however, whereas EGFR is commonly upregulated in highgrade malignancies, EGF is rarely over-expresseD. In contrast, TGF-a is frequently expressed in gliomas, which binds to EGFR and stimulates tyrosine kinase-specific activity, leading to further cell transformation. Thus, it is believed that TGF-a is the primary ligand binding to EGFR in malignant gliomas (Youmans, pp. 726-727 )

Answer 175

E . TNF-a, IL-lb, IL-6, and potassium levels have been shown to increase after DAI, while magnesium-which is involved in glycoly$iS, oxidative phosphorylation, cellular respiration, and the synthesis of DNA, RNA, and proteinshas been shown to decrease after severe head injury (Marion, pp. 40- 45)

Answer 176

B. Denervation of muscle results i n fibrillation potentials and positive sharp waves within approximately 2 to 3 weeks and 8 days, respectively. These findings persist until the muscle fibers are reinnervated (usually 3 to 4 months after mild insults) or until the denervated muscle undergoes complete atrophy (Youmans, p. 3856).

Answer 177

A. Note the multiple prominent irregularities and loculations located circumferentially around the margins of the dura on this CT myelogram, which is most consistent with arachnoiditis (Ramsey, pp. 739-7 41)

Answer 178

E. Sarcoidosis is a systemic granulomatous disease that involves the nervous system in 5% of patients (neurosarcoidosis). CNS granulomas in neurosarcoidosis can involve the cranial nerves, meninges, hypothalamus, brain parenchyma, and spinal corD. The skull base is frequently affected, and granulomas in this location may result in obstructive hydrocephalus. Cranial nerve palsies may also occur; the facial nerve is most commonly involveD. Hypothalamic granulomas can result in diabetes insipidus, galactorrhea, amenorrhea, and changes in behavior, sleep patterns, and appetitE. Sarcoidosis can also cause peripheral neuropathies, such as mononeuropathy multiplex. MRI often reveals the presence of CNS granulomas, and CSF exhibits a lymphocytic pleocytosis with elevations in IgG and the IgG index. Oligoclonal bands and elevated angiotensin-converting enzyme (ACE) levels can also be found in the CSF. Neurosarcoidosis can present as a self-limited monophasic illness or a chronic disease with relapses and remissions. Treatment of neurosarcoidosis involves corticosteroids (prednisone), with immunosuppressant drugs added in refractory cases (azathioprine, methotrexate, cyclosporine) (Merritt pp. 180-181)

Answer 179

C. Electrocerebral inactivity is consistent with brain death in the setting of a detailed brain death exam. It is defined as no cerebral electrical potentials greater than 2 1-!V. I t is not required to pronounce brain death and is used as an ancillary test when the diagnosis is not clear. Drug i ntoxication (E.g. , phenobarbital) and hypothermia may result in reversible electrocerebral inactivity (Greenberg, p . 130)

Answer 180

B . The most potentially serious complication of hyperkalemia is slowing of electrical heart conduction. The EGG begins to change when the serum W reaches approximately 6.0 mEq/L and is always abnormal when it is \> 8.0 mEq/L. The earliest EGG abnormality is a tall, tapering T wave that is most evident in the precordial leads V2 and V3. As W levels i ncrease further, the P-wave amplitude decreases and the PR i nterval lengthens. The P waves may eventually disappear and the QRS complex widen. The final event is ventricular asYstole (Marino, p p . 654-655)

Answer 181

E Occlusion of the anterior choroidal artery causes a homonymous defect in the upper CHAPTER 8 Multidisciplinary Self-Assessment Answers 279 and lower quadrants, with sparing of the horizontal sector (quadruple sectoranopia, B), which is usually characteristic of a lateral geniculate body i nfarct that is supplied by the anterior choroidal artery. The central portion of the lateral geniculate body receives blood flow primarily from the lat-. era! posterior choroidal artery. Interruption of this vessel causes a horizontal homonymous sector defect (wedgeshaped, D). Superior homonymous quadrantic defects ("piein the sky," E) may result from a lesion along Meyer's loop (after temporal lobectomy) or along the inferior bank of the calcarine fissurE. The anterior chiasm or junctional syndrome results in a unilateral optic nerve defect of one eye and a superior temporal defect in the other eye (A) due to the loop made by the inferonasal retina of the other eye (Willebrand's knee). Lesions located in the most anterior portion of the calcarine cortex cause a crescent-shaped defect restricted to the temporal field of the qontralateral eye (monocular temporal crescent, C). This is the only retrochiasmatic lesion that may result in a strictly unilateral visual field defect (Brazis, pp. 132 -140).

Answer 182

D Occlusion of the anterior choroidal artery causes a homonymous defect in the upper CHAPTER 8 Multidisciplinary Self-Assessment Answers 279 and lower quadrants, with sparing of the horizontal sector (quadruple sectoranopia, B), which is usually characteristic of a lateral geniculate body i nfarct that is supplied by the anterior choroidal artery. The central portion of the lateral geniculate body receives blood flow primarily from the lat-. era! posterior choroidal artery. Interruption of this vessel causes a horizontal homonymous sector defect (wedgeshaped, D). Superior homonymous quadrantic defects ("piein the sky," E) may result from a lesion along Meyer's loop (after temporal lobectomy) or along the inferior bank of the calcarine fissurE. The anterior chiasm or junctional syndrome results in a unilateral optic nerve defect of one eye and a superior temporal defect in the other eye (A) due to the loop made by the inferonasal retina of the other eye (Willebrand's knee). Lesions located in the most anterior portion of the calcarine cortex cause a crescent-shaped defect restricted to the temporal field of the qontralateral eye (monocular temporal crescent, C). This is the only retrochiasmatic lesion that may result in a strictly unilateral visual field defect (Brazis, pp. 132 -140).

Answer 183

A Occlusion of the anterior choroidal artery causes a homonymous defect in the upper CHAPTER 8 Multidisciplinary Self-Assessment Answers 279 and lower quadrants, with sparing of the horizontal sector (quadruple sectoranopia, B), which is usually characteristic of a lateral geniculate body i nfarct that is supplied by the anterior choroidal artery. The central portion of the lateral geniculate body receives blood flow primarily from the lat-. era! posterior choroidal artery. Interruption of this vessel causes a horizontal homonymous sector defect (wedgeshaped, D). Superior homonymous quadrantic defects ("piein the sky," E) may result from a lesion along Meyer's loop (after temporal lobectomy) or along the inferior bank of the calcarine fissurE. The anterior chiasm or junctional syndrome results in a unilateral optic nerve defect of one eye and a superior temporal defect in the other eye (A) due to the loop made by the inferonasal retina of the other eye (Willebrand's knee). Lesions located in the most anterior portion of the calcarine cortex cause a crescent-shaped defect restricted to the temporal field of the qontralateral eye (monocular temporal crescent, C). This is the only retrochiasmatic lesion that may result in a strictly unilateral visual field defect (Brazis, pp. 132 -140).

Answer 184

C Occlusion of the anterior choroidal artery causes a homonymous defect in the upper CHAPTER 8 Multidisciplinary Self-Assessment Answers 279 and lower quadrants, with sparing of the horizontal sector (quadruple sectoranopia, B), which is usually characteristic of a lateral geniculate body i nfarct that is supplied by the anterior choroidal artery. The central portion of the lateral geniculate body receives blood flow primarily from the lat-. era! posterior choroidal artery. Interruption of this vessel causes a horizontal homonymous sector defect (wedgeshaped, D). Superior homonymous quadrantic defects ("piein the sky," E) may result from a lesion along Meyer's loop (after temporal lobectomy) or along the inferior bank of the calcarine fissurE. The anterior chiasm or junctional syndrome results in a unilateral optic nerve defect of one eye and a superior temporal defect in the other eye (A) due to the loop made by the inferonasal retina of the other eye (Willebrand's knee). Lesions located in the most anterior portion of the calcarine cortex cause a crescent-shaped defect restricted to the temporal field of the qontralateral eye (monocular temporal crescent, C). This is the only retrochiasmatic lesion that may result in a strictly unilateral visual field defect (Brazis, pp. 132 -140).

Answer 185

B Occlusion of the anterior choroidal artery causes a homonymous defect in the upper CHAPTER 8 Multidisciplinary Self-Assessment Answers 279 and lower quadrants, with sparing of the horizontal sector (quadruple sectoranopia, B), which is usually characteristic of a lateral geniculate body i nfarct that is supplied by the anterior choroidal artery. The central portion of the lateral geniculate body receives blood flow primarily from the lat-. era! posterior choroidal artery. Interruption of this vessel causes a horizontal homonymous sector defect (wedgeshaped, D). Superior homonymous quadrantic defects ("piein the sky," E) may result from a lesion along Meyer's loop (after temporal lobectomy) or along the inferior bank of the calcarine fissurE. The anterior chiasm or junctional syndrome results in a unilateral optic nerve defect of one eye and a superior temporal defect in the other eye (A) due to the loop made by the inferonasal retina of the other eye (Willebrand's knee). Lesions located in the most anterior portion of the calcarine cortex cause a crescent-shaped defect restricted to the temporal field of the qontralateral eye (monocular temporal crescent, C). This is the only retrochiasmatic lesion that may result in a strictly unilateral visual field defect (Brazis, pp. 132 -140).

Answer 186

B. The musculocutaneous nerve innervates the biceps, brachialis, and coracobrachialis muscles, which control elbow flexion and forearm supination ( Brazis, p. 60).

Answer 187

D. Where the pyramidal tract decussates at the cervicomedullary junction with segregation of arm fibers (rostral) and leg fibers (caudal) , a lesion can cause the unique combination of ipsilateral arm weakness and contralateral leg paresis (cruciate paralysis) (Brazis, p . 95; Greenberg, p . 95).

Answer 188

C Hydranencephaly describes a brain replaced by CSF rather than compressed by expansion of the ventricles, as in severe hydrocephalus. Moreover, with severe hydrocephalus, there is usually a thin mantle of brain, which is absent in hydranencephaly. The absence of a cortical mantle with hydranencephaly is most often associated with angiographic evidence of supraclinoid occlusion of the carotid arteries, which strongly suggests a vascular pathogenesis. The posterior fossa and thalami are often preserved due to preserved posterior circulation. The cranium of afflicted children usually fails to grow and remains small. The incidence is estimated to be 1 in 6000, and affected infants rarely live longer than a year (Albright, pp. 155- 156)

Answer 189

C Hydranencephaly describes a brain replaced by CSF rather than compressed by expansion of the ventricles, as in severe hydrocephalus. Moreover, with severe hydrocephalus, there is usually a thin mantle of brain, which is absent in hydranencephaly. The absence of a cortical mantle with hydranencephaly is most often associated with angiographic evidence of supraclinoid occlusion of the carotid arteries, which strongly suggests a vascular pathogenesis. The posterior fossa and thalami are often preserved due to preserved posterior circulation. The cranium of afflicted children usually fails to grow and remains small. The incidence is estimated to be 1 in 6000, and affected infants rarely live longer than a year (Albright, pp. 155- 156)

Answer 190

E. DPL is considered positive if greater than 10 mL of gross blood is aspirated from the peritoneal cavity or if 1 L of lactated Ringer's solution is infused i n to the peritoneal cavity and microscopic evaluation reveals red blood cells \> 100,000/mm3, white blood cells \> 500/mm3, or the presence of bile, particulate matter, or amylase greater than the normal serum valuE. It can be used for penetrating stab wounds after positive local exploration or suspected hollow viscus injury, following an abnormal ultrasound examination, or following a normal ultrasound when the patient exhibitshemodynamic instability or signs and symptoms suggestive of an intra-abdominal injury (Nwariaku, pp. 64- 65)

Answer 191

A. Note the large, glassy eosinophilic cell bodies with an angular shape on this photomicrograph, which depicts a gemistocytic astrocytoma (Ellison, p. 627; WHO, p. 2 5)

Answer 192

C . I n conductive hearing loss o n the right, the Weber test lateralizes to the right, the Rinne test is negative (bone conduction is better than air conduction), and the Schwabach test is normal or prolonged (the patient can hear the tuning fork longer than the examiner can) (Brazis, pp. 298-299 )

Answer 193

C. With peripheral lesions, severe rotational vertigo associated with nausea and vomiting and nystagmus appear approximately 2 to 15 seconds after performing the NylenB

Answer 194

C. Note the occlusion of the blood vessel, which is due to the presence of many ghost-like red blood cells that contain parasites on this H & E section depicting malariA. Patients with this disease can present with seizures, headache, somnolence, confusion, photophobia, and almost any focal neurologic deficit. Without urgent treatment, these patients usually progress to coma and brain death (Ellison, pp. 653-656)

Answer 195

B. This photomicrograph depicts a subependymal giant cell astrocytomA. This lesion is usually located adjacent to the foramen of Monro and is associated with tuberous sclerosis (dominant mutation in TSC 1 on 9p or TSC 2 on 1 6p ). It usually resembles gemistocytic astrocytoma, but is not infiltrativE. Note the abundant cytoplasm, abundant perivascular fibrillar zone, and prominent nucleolus in this section. The nuclei are eccentric, which distinguishes this from gemistocytic astrocytoma (Elliso n , pp. 637-639)

Answer 196

. A. This constellation of clinical findings is most consistent with Parinatid's syndrome, which is often associated with pineal region masses causing direct compression of the tecta! plate or from compression of the mesencephalic tectum by a dilated suprapineal recess in cases of hydrocephalus (Greenberg, p . . 87)

Answer 197

E. SII lies along the superior bank of the lateral sulcus and extends posteriorly into the parietal lobe; it has representation of body parts in the reverse sequence to that found in the primary somesthetic area, with the two face areas being adj acent. Representation of the body is bilateral in SII (although contralateral predominates) , and the efferent cortical projections are mainly to SI and the primary motor cortex (Carpenter, pp. 404- 405).

Answer 198

A. The corpus callosum functions to transfer information from one hemisphere to the other. After sectioning, the patient cannot execute a command with the left hand but will do so consistently with the right. The left hemisphere understands the command but is unable to transfer that information to the right side of the brain. The right hemisphere does not typically understand the command because it lacks the ability to understand languagE. Therefore a patient presented with an obj ect with the right hand should be able to reliably name it, since these fibers are relayed to the contralateral cerebral cortex ( DeMyer, pp. 3 16, 3 19)

Answer 199

B. The most common locations for hypertensive intracranial hemorrhage include the putamen, followed by the thalamus, pons, cerebellum, and lobar regions. The origin of some "hypertensive" putamina! hemorrhages are believed to result from microaneurysms of "Charcot-Bouchard, " but this is somewhat controversial (Greenberg, p. 815)

Answer 200

D. Hydrocephalus, gait disturbance ("magnetic gait" with short, shuffling steps), dementia (primarily memory impairment with bradyphrenia or slowness of thought) , incontinence, and transient elevations in intracranial pressure (with monitoring) may all occur with normal pressure hydrocephalus (NPH). Headache and papilledema are typically not seen in patients with NPH; their presence should raise suspicion of another diagnosis (Greenberg, pp. 191- 194)

Answer 201

A . The seizure spikes are over a fairly wide area o f the right parasagittal region (maximal F4 , C4) consistent with a right frontal onset corresponding with a right parasagittal meningiomA. In order to localize seizure foci, it is imperative for clinicians to memorize standard electrode placement and designations. Note that by convention, electrodes designated with odd numbers are on the left, while with even numbers on the right. The standard electrode designations are as follows: Fp1/Fp2 = frontopolar or prefrontal; F3/F4 = midfrontal; C3/C4 = central (roughly over central sulcus); P3/P4 = parietal; 0 1/02 = occipital; F7 /F8 = inferior frontal (sometimes called anterior frontal) ; T3/T4 = midtemporal (records activity over anterior and midtemporal activity, important for temporal lobe epilepsy); T5/T6 = posterior temporal; Fz, Cz, Pz = midline electrodes in frontal and parietal regions (record mesial surfaces of hemispheres) ; A1/A2 = ear reference electrodes (while used for references also record midtemporal activity); T1/T2 = so-called true anterior temporal electrodes; Sp 1/Sp2 = sphenoidal electrodes (recordactivity from inferomesial surface of the temporal lobes) ( Rowan, pp. 4-7 )

Answer 202

D Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 203

E Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 204

F Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 205

C Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 206

A Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 207

B Fibers o f the ansa lenticularis (D) leave the outer part of the medial globus pallidus, pass around the internal capsule, and enter the prerubral field (field H of Fore!, not labeled) prior to merging with the lenticular fasciculus (H2) . Fibers of the lenticular fasciculus originate from the inner part of the medial globus pallidus, traverse the posterior limb of the anterior capsule, and pass medially, dorsal to the subthalamic nucleus, to also enter the prerubral fielD. The ansa lenticularis and lenticular fasciculus then travel together dorsal to the zona incerta as components of the thalamic fasciculus (A). The subthalamic fasciculus (C) is comprised of pallidosubthalamic fibers originating from the lateral or external pallidal segment and subthalamopallidal fibers that terminate in the medullary lamina of both pallidal segments. Both components of the subthalamic fasciculus cross the internal capsulE. Thalamostriate fibers from the centromedian nucleus project to the putamen ( E) (Carpenter, pp. 33 7-345)

Answer 208

C. Note the prominent ring enhancement of this spinal epidural abscess, with compression of the adjacent spinal corD. The most likely causative organism in a patient with a history of intravenous drug abuse is Staph. aureus ( Ramsey, pp. 498-502 )

Answer 209

B. Necrotizing wound infections are produced by Clostridium and P-hemolytic streptococcal species. Unlike other wound infections that may appear a few days to 1 week after surgery, necrotizing infections are evident in the first few postoperative days; they are characterized by skin crepitance and fluid-filled bullaE. Spread to deeper tissues is a major concern, as this may result i n rhabdomyolysis and myoglobinuric renal failure ( M arino, p. 489)

Answer 210

D. There are three main branches that originate from the intracavernous portion of the ICA: the meningohypophyseal trunk, the artery of the inferior cavernous sinus, and the artery of McConnell. The meningohypophyseal trunk trifurcates into the tentorial artery (of Bernasconi and Cassinari), the dorsal meningeal artery (supplies dura over dorsum sellae), and the inferior hypophyseal artery, which supplies the posterior pituitary gland and sellar floor. McConnell's artery runs along the dura covering the sellar floor to supply the anterior pituitary gland, while the artery of the inferior cavernous sinus provides blood supply to the third, fourth, and sixth cranial nerves as well as the gasserian ganglion and cavernous sinus durA. The vidian artery originates from the petrous ICA (Osborn DCA, pp. 86-87).

Answer 211

. A. Patients with entrapment or trauma to the suprascapular nerve often complain of shoulder pain centered over the lateral scapula and posterior shoulder, which is most CHAPTER 8 Multidisciplinary Self-Assessment Answers 2 8 1 often aggravated by arm abduction during the first 15 degrees (supraspinatus muscle) and external arm rotation when the elbow is flexed at 90 degrees (infraspinatus muscle) . Atrophy of the supraspinatus and infraspinatus muscles may also be apparent on inspection. EMG reveals denervation potentials in the supraspinatus and i nfraspinatus muscles and is the best diagnostic test. Conservative treatment measures include shoulder exercises and local injections of steroids and analgesics. Operative decompression usually includes sectioning of the suprascapular ligament (Youmans, pp. 3932- 3933)

Answer 212

C. Patients with osteoid osteoma involving the lumbar spine typically present with back pain that is exacerbated at night. This condition is believed to result from prostaglandin production by the tumor. Aspirin has classically been shown to relieve the pain (Youmans, p. 4297)

Answer 213

C. Atonic seizures, also called "drop attacks," are characterized by total loss of muscle tonE. When they are preceded by a brief myoclonic seizure or tonic .spasm, an acceleratOT)' force is added to the fall, further contributing to the high rate of self-injUT)' with this type of seizurE. Most patients referred for corpus callosotomy have severe, medically refractory seizures usually accompanied by mental retardation and a severely abnormal EEG. Unlike lesionectomy, corpus callosotomy is palliative, not curativE. Nevertheless, this procedure can be highly effective for generalized seizures, with 80% of patients experiencing complete or nearly complete cessation of atonic, tonic, and tonic-clonic attacks in some reports (Merritt, pp. 814, 827).

Answer 214

D The spinal accessory nerve is at particular risk during lymph node biopsies involving the posterior triangle of the neck. Patients typically present within a week \Yith a shoulder droop or inability to raise the arm. An additional sensory complaint is noted in some patients from injury to the greater auricular and lesser occipital nerves, which course behind the sternocleidomastoid muscle in close proximity to the spinal accessory nervE. Fortunately, most patients exhibit spontaneous resolution of symptoms (Committee on Education in Neurological Surgery, p. 113; Donner et a l . , pp. 907-910)

Answer 215

B The spinal accessory nerve is at particular risk during lymph node biopsies involving the posterior triangle of the neck. Patients typically present within a week \Yith a shoulder droop or inability to raise the arm. An additional sensory complaint is noted in some patients from injury to the greater auricular and lesser occipital nerves, which course behind the sternocleidomastoid muscle in close proximity to the spinal accessory nervE. Fortunately, most patients exhibit spontaneous resolution of symptoms (Committee on Education in Neurological Surgery, p. 113; Donner et a l . , pp. 907-910)

Answer 216

E . MEG has several advantages over E E G recording. First, unlike EEG-based techniques, which measure electrical potentials mainly from extracellular volume currents, the magnetic fields measured with MEG primarily reflect intracellular current flow and are not attenuated by the inhomogeneously conducting layers of bone, scalp, and other extracerebral tissuE. This provides excellent spatial and temporal resolution for localization of neuronal activity, and it more accurately represents the localization of eloquent cortex than EEG. Second, mass lesions or other pathologic changes in the brain, which may significantly distort the signal detectedby EEG, do not affect the signal detected by MEG. Third, because MEG includes only a tangential component of neuronal current, as opposed to EEG recording (which uses both tangential and radial component), the signal detected is less complex than the signal detected by EEG. And finally, whereas EEG reflects only surface recordings, MEG includes data points below the surface of the brain as well. Magnetic source imaging (MSI) is a technique that allows the mapping of brain function onto brain structure by combining the functional data obtained by MEG with the neuroanatomic data obtained by MRI studies. By mapping the neurophysiologic data acquired by MEG onto the neuroanatomic data acquired by MRI, the functional measures can be given an accurate anatomic reference, which can often help guide surgery. Nevertheless, despite the obvious advantages of MEG and MSI, these strategies are not widely employeD. The high financial cost of acquiring such units and the labor-intensive effort that is required by both patients and clinicians during data analysis are just two of the more noteworthy reasons these techniques have not gained universal favor (American Society of Pediatric Neurosurgeons, p p . 1048- 1049)

Answer 217

C Note the expansion of bone (sphenoid) and "ground glass appearance" on this noncontrasted CT scan in a patient with fibrous dysplasiA. Malignant degeneration, usually to osteosarcoma, has been reported to occur in approximately 0 . 5% of patients with fibrous dysplasia (Albright, pp. 456-457).

Answer 218

D Note the expansion of bone (sphenoid) and "ground glass appearance" on this noncontrasted CT scan in a patient with fibrous dysplasiA. Malignant degeneration, usually to osteosarcoma, has been reported to occur in approximately 0 . 5% of patients with fibrous dysplasia (Albright, pp. 456-457).

Answer 219

C. The stylopharyngeus muscle is innervated by the glossopharyngeal nerve (IX) and is the only muscle derived from the third brachial arch. The muscles of facial expression are all innervated by the facial • nerve (VII) and are derived from the second brachial arch, whereas the thyroarytenoid muscle and intrinsic laryngeal musculature (except cricothyroid muscle, fourth arch derivative) are derived from the sixth brachial arch. The muscles of mastication are derived from the first brachial arch and are innervated by the mandibular division of the trigeminal nerve (Apri l , p. 556)

Answer 220

D. Note the paucity of blood flow in the distal internal carotid and cerebral artery vasculature and the presence of prominent collaterals that resemble a "puff of smoke" on this lateral angiogram, which depicts moyamoya (Albright, pp. 1053-1069).

Answer 221

C. The ganglion cells in the retina gives rise to the optic nervE. The ganglion cells receive impulses from the bipolar cells, which, in turn, receive signals from the light-sensitive rods and cones ( Kandel, .PP• 517 - 521)

Answer 222

C With neurotmesis, there is complete anatomic transection of the nerve accompanied by Wallerian degeneration. These injuries almost always require surgical repair, although the timing remains unclear. For sharply divided nerves, immediate repair appears to be ideal, whereas for bluntly injured nerves, some advocate waiting approximately 3 to 4 weeks prior to intervening surgically to allow for better proximal and distal nerve stump delineation. With axonotmesis, there is a loss of axonal continuity, but the soma remains continuous. Wallerian degeneration also occurs with this type of insult. With neurapraxia, conduction ceases without structural damage to the nervE. There is a physiologic transection, which is often accompanied by defective axonal transport. This type of nerve injury frequently recovers by 6 to 8 weeks on averagE. Stimulating distal to a nerve lesion at about 1 week postinjury results in no action potentials if \Vallerian degeneration occurs (Greenberg, p. 532 ; Youmans, p p . 3825-3826)

Answer 223

B With neurotmesis, there is complete anatomic transection of the nerve accompanied by Wallerian degeneration. These injuries almost always require surgical repair, although the timing remains unclear. For sharply divided nerves, immediate repair appears to be ideal, whereas for bluntly injured nerves, some advocate waiting approximately 3 to 4 weeks prior to intervening surgically to allow for better proximal and distal nerve stump delineation. With axonotmesis, there is a loss of axonal continuity, but the soma remains continuous. Wallerian degeneration also occurs with this type of insult. With neurapraxia, conduction ceases without structural damage to the nervE. There is a physiologic transection, which is often accompanied by defective axonal transport. This type of nerve injury frequently recovers by 6 to 8 weeks on averagE. Stimulating distal to a nerve lesion at about 1 week postinjury results in no action potentials if \Vallerian degeneration occurs (Greenberg, p. 532 ; Youmans, p p . 3825-3826)

Answer 224

D With neurotmesis, there is complete anatomic transection of the nerve accompanied by Wallerian degeneration. These injuries almost always require surgical repair, although the timing remains unclear. For sharply divided nerves, immediate repair appears to be ideal, whereas for bluntly injured nerves, some advocate waiting approximately 3 to 4 weeks prior to intervening surgically to allow for better proximal and distal nerve stump delineation. With axonotmesis, there is a loss of axonal continuity, but the soma remains continuous. Wallerian degeneration also occurs with this type of insult. With neurapraxia, conduction ceases without structural damage to the nervE. There is a physiologic transection, which is often accompanied by defective axonal transport. This type of nerve injury frequently recovers by 6 to 8 weeks on averagE. Stimulating distal to a nerve lesion at about 1 week postinjury results in no action potentials if \Vallerian degeneration occurs (Greenberg, p. 532 ; Youmans, p p . 3825-3826)

Answer 225

A With neurotmesis, there is complete anatomic transection of the nerve accompanied by Wallerian degeneration. These injuries almost always require surgical repair, although the timing remains unclear. For sharply divided nerves, immediate repair appears to be ideal, whereas for bluntly injured nerves, some advocate waiting approximately 3 to 4 weeks prior to intervening surgically to allow for better proximal and distal nerve stump delineation. With axonotmesis, there is a loss of axonal continuity, but the soma remains continuous. Wallerian degeneration also occurs with this type of insult. With neurapraxia, conduction ceases without structural damage to the nervE. There is a physiologic transection, which is often accompanied by defective axonal transport. This type of nerve injury frequently recovers by 6 to 8 weeks on averagE. Stimulating distal to a nerve lesion at about 1 week postinjury results in no action potentials if \Vallerian degeneration occurs (Greenberg, p. 532 ; Youmans, p p . 3825-3826)

Answer 226

C. The acquisition of bony spinal fusion increases motion and stress at adjacent motion segments, which can accelerate degenerative changes. This process is further enhanced by failure to repair sagittal balance during surgery. Although not the ideal study to evaluate bony fusion, this MRI does not demonstrate pseudoarthrosis at the prior fusion site, subsidence, basilar invagination, or osteomyelitis. It shows end-fusion degenerative changes and loss of the normal lordotic curve of the cervical spine, which may be contributing to this patients' new clinical problems (Benzel, p. 130)

Answer 227

B This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 228

C This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 229

D This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 230

A This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 231

E This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 232

F This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 233

G This diagram shows the structures that traverse the internal auditory canal (IAC). The facial nerve (A) and nervus intermedius are separated from the superior vestibular nerve by a vertical crest of bone known as Bill's bar (F) . Bill's bar arises from the transverse crest (G) within the lateral aspect of the IAC. The cochlear nerve (C) and inferior vestibular nerve enter the IAC inferior to the transverse crest, as depicted in the diagram (Wil kins, pp. 1063-10 7 1, 1 101-1114)

Answer 234

A. Three forms of lipomyelomeningocele have been described that have clinical relevance: dorsal, caudal (terminal ) , and transitional. They are believed to arise from faulty disjunction of the neuroectoderm from the overlying ectoderm, which leaves gaps between these two developing layers. Subsequently, mesenchymal cells are believed to ingress through these defective areas into the central canal, where they are induced to form a bulk of lipomatous tissue, which subsequently prevents fusion or complete closure of the neural tubE. 'With dorsal lipomas, the rootlets generally lie ventrolateral to the dorsal root entry zone, a crucial anatomic landmark during surgical procedures. Embryologically, this is related to the fact that neural crest cells lie immediately ventrolateral to the point of disjunction of cutaneous and neuroectoderm. Therefore, for many of the dorsal lipomas, ifsurgeons stay dorsomedial to the dorsal root entry zone, they will likely avoid neurologic injury. Transitional and/or caudal lipomas may be more challenging: as the anatomy is usually distorted, the lipoma-cord interface is usually less predictable, and the exiting roots may be enmeshed with lipomA. SSEP, EMG, or other monitoring procedures may serve as useful adjuncts during these challenging procedures (Youmans, pp. 3229-4243 ; American Society of Pediatric Neurosurgeons, pp. 289-301; Kaye and Black, pp. 2026- 2 03 7 )

Answer 235

C. Three forms of lipomyelomeningocele have been described that have clinical relevance: dorsal, caudal (terminal ) , and transitional. They are believed to arise from faulty disjunction of the neuroectoderm from the overlying ectoderm, which leaves gaps between these two developing layers. Subsequently, mesenchymal cells are believed to ingress through these defective areas into the central canal, where they are induced to form a bulk of lipomatous tissue, which subsequently prevents fusion or complete closure of the neural tubE. 'With dorsal lipomas, the rootlets generally lie ventrolateral to the dorsal root entry zone, a crucial anatomic landmark during surgical procedures. Embryologically, this is related to the fact that neural crest cells lie immediately ventrolateral to the point of disjunction of cutaneous and neuroectoderm. Therefore, for many of the dorsal lipomas, ifsurgeons stay dorsomedial to the dorsal root entry zone, they will likely avoid neurologic injury. Transitional and/or caudal lipomas may be more challenging: as the anatomy is usually distorted, the lipoma-cord interface is usually less predictable, and the exiting roots may be enmeshed with lipomA. SSEP, EMG, or other monitoring procedures may serve as useful adjuncts during these challenging procedures (Youmans, pp. 3229-4243 ; American Society of Pediatric Neurosurgeons, pp. 289-301; Kaye and Black, pp. 2026- 2 03 7 )

Answer 236

C. Three forms of lipomyelomeningocele have been described that have clinical relevance: dorsal, caudal (terminal ) , and transitional. They are believed to arise from faulty disjunction of the neuroectoderm from the overlying ectoderm, which leaves gaps between these two developing layers. Subsequently, mesenchymal cells are believed to ingress through these defective areas into the central canal, where they are induced to form a bulk of lipomatous tissue, which subsequently prevents fusion or complete closure of the neural tubE. 'With dorsal lipomas, the rootlets generally lie ventrolateral to the dorsal root entry zone, a crucial anatomic landmark during surgical procedures. Embryologically, this is related to the fact that neural crest cells lie immediately ventrolateral to the point of disjunction of cutaneous and neuroectoderm. Therefore, for many of the dorsal lipomas, ifsurgeons stay dorsomedial to the dorsal root entry zone, they will likely avoid neurologic injury. Transitional and/or caudal lipomas may be more challenging: as the anatomy is usually distorted, the lipoma-cord interface is usually less predictable, and the exiting roots may be enmeshed with lipomA. SSEP, EMG, or other monitoring procedures may serve as useful adjuncts during these challenging procedures (Youmans, pp. 3229-4243 ; American Society of Pediatric Neurosurgeons, pp. 289-301; Kaye and Black, pp. 2026- 2 03 7 )

Answer 237

B. The ethmoid bone (vertical plate) and vomer contribute to the anterosuperior and posteroinferior portions of the nasal septum, respectively. The nasal bones and nasal crests of the frontal bones make smaller contributions (Moore, p . 945)

Answer 238

C. Viral infections of the CNS can result in meningitis, ventriculitis, encephalitis, and myelitis. CSF in patients with viral syndromes of the CNS reveals increased pressure, lymphocytic pleocytosis, mild elevations in protein, and normal glucose levels. Viral (aseptic) meningitis usually peaks in the summer and fall seasons, whereas bacterial meningitis is more common during the winter. The most common causes of viral meningitis are the enteroviruses, but togaviruses are also frequent pathogens. Encephalitis often results from infections with herpes simplex virus, mumps, or arboviruses (Merritt, pp. 134-138)

Answer 239

E. Night terrors most commonly occur during stages 3 and 4 of deep sleep. During a night terror, the child appears extremely frightened and agitated and, although seemingly awake, is actually in deep sleep (stage 3 or 4) and is difficult to rousE. Upon awakening, the child has no apparent memory of the event. Although concerning to parents, night CHAPTER 8 Multidisciplinary Self-Assessment Answers 283 terrors are felt to be benign and self-limited (Rudolph, p. 28; Merritt, p. 15).

Answer 240

C. The clinical history of this patient and destructive MRI appearance of this lesion are highly suggestive of a malignant neoplasm involving the paranasal sinuses. The histologic and immunohistochemical markers are most consistent with esthesioneuroblastoma (Kaye and Laws, pp. 885-889)

Answer 241

D. Sympathetic nervous system fibers (traveling with the internal carotid artery) and cranial nerve VI are in close proximity in the cavernous sinus. Tumors' or other lesions in this location may produce oculosympathetic paralysis (without anhidrosis) (Brazis, p. 265)

Answer 242

B. Vertical and torsional saccadic eye movements are generated by the rostral interstitial nucleus of the 1v1LF (riMLF), located in the prerubral field of the ventral diencephalomesencephalic junction, rostral to the tractus retroflexus and ventral to the nucleus of Darkschewitsch. Although cells involved with downward saccades are different from the ones involved with upward saccades, they are dispersed throughout the riMLF without separation of upward and downward pools ( Brazis, pp. 199-200)

Answer 243

A Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 244

D Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 245

G Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 246

A Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 247

F Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 248

D Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 249

H Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 250

C Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 251

E Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 252

B Refer to Table 8.267-8.276A (Tarsy, pp. 192-193, 206)

Answer 253

E. Denervation typically causes atrophy of muscle fibers, which eventually become angulated, as well as the formation of distinctive fibers with three unique zones often referred to as "target cells. " Reinnervation is characterized by type-specific grouping of fibers, which is in contrast to themixed, "checkerboard" pattern of types 1 and 2 skeletal fibers and the atrophic, angulated cells of denervated fibers. Eosinophils in muscle cells are often seen with parasitic infections ( Merritt, p. 736)

Answer 254

A. Within this tuberculoma, note the prominent region of caseating necrosis (left), in which no cellular detail can be ascertaineD. A peripheral rim of lymphocytes and a fibrous capsule surround the granuloma, and an occasional histiocyte is observed (Ellison , pp. 339-342)

Answer 255

C . Note the multiple lesions at the gray-white junction, which is most consistent with metastatic disease (Ellison, pp. 743-750)

Answer 256

D . The right and left posterior cricoarytenoid muscles abduct the vocal cords (Moore, p. 1060)

Answer 257

A. Injecting cold water into the right ear causes the endolymph to move away from the ampulla of the horizontal canal. This causes a decreased tone of input into the left abducens nucleus, which results in slow conjugate eye movements toward the right due to right lateral rectus and left medial rectus contraction. Subsequently, there will be compensatory fast eye movements (left-beating nystagmus) to the left. Warm water injected into the right ear will produce the opposite responsE. The mnemonic COWS (cold opposite; warm same) helps define the fast phase of eye movements during caloric testing (Kline, pp. 57-59 )

Answer 258

C Refer t o discussion questions 55 -58, neuroanatomy chapter (Geyer, p. 27 4 ; Greenberg, pp. 576- 5 78)

Answer 259

B Refer t o discussion questions 55 -58, neuroanatomy chapter (Geyer, p. 27 4 ; Greenberg, pp. 576- 5 78)

Answer 260

D Refer t o discussion questions 55 -58, neuroanatomy chapter (Geyer, p. 27 4 ; Greenberg, pp. 576- 5 78)

Answer 261

D Refer t o discussion questions 55 -58, neuroanatomy chapter (Geyer, p. 27 4 ; Greenberg, pp. 576- 5 78)

Answer 262

A Refer t o discussion questions 55 -58, neuroanatomy chapter (Geyer, p. 27 4 ; Greenberg, pp. 576- 5 78)

Answer 263

B Brightness modulation ultrasonography (B mode) , based on reflection of sound waves off tissue interfaces, is better used to view anatomic detail and can be used to measure blood vessel diameter and evaluate plaques. It typically shows the carotid system as a pulsatile luminal structure, with a thin echogenic line representing the intimal surfacE. The basic principle underlying this mode of irriaging is the variable impedance that different body tissues naturally possess. Doppler shift ultrasonography is based on the reflection of sound waves off moving targets such as red blood cells. It is better for evaluating flow dynamics such as blood velocity, which typically increases in segments of stenosis. Although the combination of B-mode and Doppler ultrasoqography improved the ability to localize the source of the reflected signal when it was involved with complicated blood velocity patterns (vasospasm, atherosclerosis) , the signal was still quit difficult to interpret. More recently, through the use of fast Fourier transformations, the complex signal ,,•as separated into a number of single-frequency components, which made it easier to interpret. These technologies were later integrated, and duplex ultrasonography was born. The advantage of duplex scanning compared to the pre-existing technology is that it could sample flow within a vessel while simultaneously displaying vessel wall anatomy (Youmans, pp. 1561- 1565 )

Answer 264

B Brightness modulation ultrasonography (B mode) , based on reflection of sound waves off tissue interfaces, is better used to view anatomic detail and can be used to measure blood vessel diameter and evaluate plaques. It typically shows the carotid system as a pulsatile luminal structure, with a thin echogenic line representing the intimal surfacE. The basic principle underlying this mode of irriaging is the variable impedance that different body tissues naturally possess. Doppler shift ultrasonography is based on the reflection of sound waves off moving targets such as red blood cells. It is better for evaluating flow dynamics such as blood velocity, which typically increases in segments of stenosis. Although the combination of B-mode and Doppler ultrasoqography improved the ability to localize the source of the reflected signal when it was involved with complicated blood velocity patterns (vasospasm, atherosclerosis) , the signal was still quit difficult to interpret. More recently, through the use of fast Fourier transformations, the complex signal ,,•as separated into a number of single-frequency components, which made it easier to interpret. These technologies were later integrated, and duplex ultrasonography was born. The advantage of duplex scanning compared to the pre-existing technology is that it could sample flow within a vessel while simultaneously displaying vessel wall anatomy (Youmans, pp. 1561- 1565 )

Answer 265

A Brightness modulation ultrasonography (B mode) , based on reflection of sound waves off tissue interfaces, is better used to view anatomic detail and can be used to measure blood vessel diameter and evaluate plaques. It typically shows the carotid system as a pulsatile luminal structure, with a thin echogenic line representing the intimal surfacE. The basic principle underlying this mode of irriaging is the variable impedance that different body tissues naturally possess. Doppler shift ultrasonography is based on the reflection of sound waves off moving targets such as red blood cells. It is better for evaluating flow dynamics such as blood velocity, which typically increases in segments of stenosis. Although the combination of B-mode and Doppler ultrasoqography improved the ability to localize the source of the reflected signal when it was involved with complicated blood velocity patterns (vasospasm, atherosclerosis) , the signal was still quit difficult to interpret. More recently, through the use of fast Fourier transformations, the complex signal ,,•as separated into a number of single-frequency components, which made it easier to interpret. These technologies were later integrated, and duplex ultrasonography was born. The advantage of duplex scanning compared to the pre-existing technology is that it could sample flow within a vessel while simultaneously displaying vessel wall anatomy (Youmans, pp. 1561- 1565 )

Answer 266

A Brightness modulation ultrasonography (B mode) , based on reflection of sound waves off tissue interfaces, is better used to view anatomic detail and can be used to measure blood vessel diameter and evaluate plaques. It typically shows the carotid system as a pulsatile luminal structure, with a thin echogenic line representing the intimal surfacE. The basic principle underlying this mode of irriaging is the variable impedance that different body tissues naturally possess. Doppler shift ultrasonography is based on the reflection of sound waves off moving targets such as red blood cells. It is better for evaluating flow dynamics such as blood velocity, which typically increases in segments of stenosis. Although the combination of B-mode and Doppler ultrasoqography improved the ability to localize the source of the reflected signal when it was involved with complicated blood velocity patterns (vasospasm, atherosclerosis) , the signal was still quit difficult to interpret. More recently, through the use of fast Fourier transformations, the complex signal ,,•as separated into a number of single-frequency components, which made it easier to interpret. These technologies were later integrated, and duplex ultrasonography was born. The advantage of duplex scanning compared to the pre-existing technology is that it could sample flow within a vessel while simultaneously displaying vessel wall anatomy (Youmans, pp. 1561- 1565 )

Answer 267

D Brightness modulation ultrasonography (B mode) , based on reflection of sound waves off tissue interfaces, is better used to view anatomic detail and can be used to measure blood vessel diameter and evaluate plaques. It typically shows the carotid system as a pulsatile luminal structure, with a thin echogenic line representing the intimal surfacE. The basic principle underlying this mode of irriaging is the variable impedance that different body tissues naturally possess. Doppler shift ultrasonography is based on the reflection of sound waves off moving targets such as red blood cells. It is better for evaluating flow dynamics such as blood velocity, which typically increases in segments of stenosis. Although the combination of B-mode and Doppler ultrasoqography improved the ability to localize the source of the reflected signal when it was involved with complicated blood velocity patterns (vasospasm, atherosclerosis) , the signal was still quit difficult to interpret. More recently, through the use of fast Fourier transformations, the complex signal ,,•as separated into a number of single-frequency components, which made it easier to interpret. These technologies were later integrated, and duplex ultrasonography was born. The advantage of duplex scanning compared to the pre-existing technology is that it could sample flow within a vessel while simultaneously displaying vessel wall anatomy (Youmans, pp. 1561- 1565 )

Answer 268

A . Spinobulbar muscular atrophy (SBMA), or Kennedy's disease, is a trinucleotide repeat disorder (CAG) that involves mutations of the androgen receptor gene, which is located on the X chromosomE. It is an X-linked recessive disorder that typically affects adult males in the third decade of life and results in lower motor neuron degeneration only. Symptoms are similar to ALS and include dysarthria, dysphagia, limb weakness, hyporeflexia, and tongue fasciculations. SMBA progresses much more slowly than ALS, and patients may survive for extended periods after initial symptom onset (Merritt, pp. 709-7 10).

Answer 269

. E. Antipsychotics decrease the efficacy of levodopa by inhibiting D2 receptors. Dose-related, reversible side effects include nausea, vomiting, orthostatic hypotension, dyskinesias, restlessness, anxiety, athetosis, insomnia, hallucinations, mania, nightmares, and dystonia (Merritt, pp. 689-691)

Answer 270

B. The Ramsay Hunt syndrome is associated with herpetic infections of the geniculate ganglion. Herpetic eruptions may appear in the pinna, EAC, and possibly on the tympanic membranE. It is most often associated with a lower seventh cranial nerve palsy, although there may also be decreased hearing, tinnitus, and/or vertigo from involvement of CN VIII (Greenberg, p. 381)

Answer 271

D. The positive symptoms of schizophrenia, such as hallucinations, are the direct result of dopamine overactivity in the mesolimbic pathway. Most antipsychotics work by blocking the dopamine receptors in this pathway and often work well for the positive symptoms of schizophreniA. The negative symptoms (flat affect, decreased motivation) are the result of decreased dopamine in the mesocortical system and are often not improved with the commencement of antipsychotics ( Kandel, p. 1203 )

Answer 272

A . The masseter, temporalis, and medial pterygoid muscles are the prime elevators of the mandible, whereas the buccinator muscle compresses the cheek (Apri l , pp. 496, 504) .

Answer 273

B. Note the empty delta sign, representing an occluded superior sagittal sinus. This abnormality may be associated with pregnancy, dehydration, infections, hypercoagulable states, and tumors (as in this case) (Merritt, pp. 269- 2 7 1 )

Answer 274

E . Insulin may or may not be used initially in patients with HHNS. Serum glucose levels may drop precipitouslywith fluid replacement alonE. Insulin is required for patients who are acidotic, hyperkalemic, or in renal failurE. If insulin is used, it must be administered in a low-dose regimen as a continuous infusion. To avoid overcorrection, glucose levels must be monitored frequently and the insulin drip stopped once glucose levels fall below 300 mg/dL or so. At this point 5% dextrose should be added to the infusion. Treatment of HHNS focuses primarily on replacing fluid losses, which may be up to 9 to 12 L in some cases, as well as correcting the CHAPTER 8 Multidisciplinary Self-Assessment Answers 285 hyperosmolarity and any electrolyte imbalance (Merritt, pp. 292-293)

Answer 275

C Methotrexate may cause leukoencephalopathy, myelosuppression, nephrotoxicity, and mucositis; if administered intrathecally, it can cause arachnoiditis. Bleomycin is associated with Raynaud's phenomenon, myelosuppression, and pulmonary fibrosis, while vincristine can. cause a peripheral neuropathy (Kay and Laws, pp. 381-383).

Answer 276

A Methotrexate may cause leukoencephalopathy, myelosuppression, nephrotoxicity, and mucositis; if administered intrathecally, it can cause arachnoiditis. Bleomycin is associated with Raynaud's phenomenon, myelosuppression, and pulmonary fibrosis, while vincristine can. cause a peripheral neuropathy (Kay and Laws, pp. 381-383).