121-150

Question 1

The turn of the facial nerve from its tympanic segment to its vertical segment (second genu) is just in front and below WHICH semicircular canal?

A. Horizontal (lateral) canal

B. Posterior canal

C. Superior canal

Answer 1

A. Horizontal (lateral) canal

Question 2

When performing a spinal bone fusion and considering different potential graft materials, which of the following is TRUE?

A. Autogenous bone is osteoconductive and osteogenic but not osteoinductive.

B. Allograft bone and demineralized bone matrix are both osteoconductive.

C. Bone marrow and bone growth factors are both osteogenic.

D. Neither autogenous bone nor bone growth factors are osteoinductive.

E. Autogenous and allograft bone both have osteogenic capability.

Answer 2

B. Allograft bone and demineralized bone matrix are both osteoconductive.

Question 3

Pathology of the anterior craniovertebral junction can be approach using either the transoral or the anterolateral cervical approach. The decision to use one of these approaches instead of the other is based on WHICH of the following?

A. The anterolateral operation provides a wider exposure to lateral masses of C1 and C2.

B. The lower cervical vertebrae are surgically obtainable through the same incision in the transoral operation

C. The anterolaterala operation does not cross oral mucosa and is considered appropriate when a bone fusion and/or internal stabilization is utilized.

D. All of the above

E. A and C only

Answer 3

E. A and C only

Question 4

The concept of anterior column load sharing when used in reference to internal stabilization and fusion with the lumbar spine refers to WHICH of the following?

A. The anterior column bears the majority of all the forces in all constructs.

B. A structural support in the anterior column significantly decreases the forces on the posterior internal stabilization hardware and increases the stability of the construct.

C. After the discectomy, the anterior column bears an additional percentage of the body weight.

D. In a lumbar fusion, the posterior lumbal fusion initially bears a significant amount of the anterior column load because of the anterior placement of the bone fragments on the transverse process.

Answer 4

B. A structural support in the anterior column significantly decreases the forces on the posterior internal stabilization hardware and increases the stability of the construct.

Question 5

. When internally stabilizing the lumbar spine with the segmental fixation involving pedicle screws, which of the following statement is TRUE?

A. With no transfixator, the two vertebral segments are unstable in lateral load until the spinal column load shares if the pedicle screw angle is 0 o .

B. The lateral load stability is significantly enhanced if the pedicle is 30 degrees or larger.

C. The use of a transfixation inceases both the rotational and the lateral load stability of the construct.

D. All of the above

E. None of the above

Answer 5

D. All of the above

Question 6

. Shortly after starting the intracapsular debulking of an acoustic neurinoma using the retromastoid approach in the sitting position, the monitoring technician tells you that the auditory evoked potential of the side of the tumor has changed. The baseline recordings showed mild delays from Wave I to III, but wave I, III, and V were present and reproducible. Now, Wave I is unchanged in latency an ampilude, but Wave III and V are significantly prolonged in latency and greatly (>75%) diminished in amplitude. Which of the following is LIKELY to cause this type of change?

A. Compromise of the internal auditory artery resulting in ischemia at the cochlea

B. Compromise of the VIIIth nerve in the posterior fossa

C. Technical problems with the stimulator resulting in intensity of stimulation being decreased from 95 to 30 dB

D. Increase of end-tidal isoflurane from 0.4 to 0.8%

E. All of the above

Answer 6

B. Compromise of the VIIIth nerve in the posterior fossa

Question 7

Which of the following statements is TRUE of the identification and monitoring of motor cranial nerves?

A. The differentiation of the Vth from the VIIth cranial nerve is based primarily from the location of the stimulated structure in the operative field, since both nerve produce electromyogram responses which are very similar in latency, amplitude, and morphology when electrical stimulation is applied in the posterior fossa.

B. A National Institute of Health Consensus Development Conference concluded that the benefits of routine VIIth nerve monitoring are not yet clearly established but that such monitoring should be considered in the surgical treatment of vestibular schwannoma.

C. Cranial nerves III, IV, VI cannot be monitored independently of one another due to linking via the medial longitudinal fasciculus.

D. Motor cranial nerve monitoring is best carried out using moderate muscle relaxation (i.e. pancuronium) to reduce the frequency of false-positive responses to stimulation.

E. None of the above

Answer 7

E. None of the above

Question 8

Regarding the use of somatosensory evoked potentials (SSEPs) in the oprating room. Which of the following statement is TRUE?

A. Recording of medial nerve SSEP responses from the cortical surfaces can be used to determine the location of the central sulcus in the hand area.

B. Reliable SSEP responses from structures rostral to the medulla cannot be recorded at the levels of pentobarbital bolus and infusion which provide cerebral protection from ischemia/hypoxia (i.e., sufficient to produce burst-suppression on the electroencephalogram (EEG)).

C. The blood supply to the SSEP pathway in the internal capsule is usually from the lenticulostriate arteries, thus, SSEPs can reliably be used to monitor the motor pathways in this area

. D. The spinal pathway for median nerve SSEPs is in the dorsal columns, which derive their blood supply from the anterior spinal artery.

E. None of the above.

Answer 8

A. Recording of medial nerve SSEP responses from the cortical surfaces can be used to determine the location of the central sulcus in the hand area.

Question 9

Regarding the determination of the need for shunting during carotid endarterectomy, which of the following statement is (are) TRUE?

A. The most common EEG pattern observed after clamping of the internal carotid artery is ipsilateral slowing and amplitude reduction.

B. Normal cerebral blood flow is 45-50 ml/100g/min, electroencephalography (EEG) changes are seen at 15-20 ml/100g/min, and cellular survival is threatened at 10-15 ml/100g/min.

C. Shunting patients without evidence of decreased cerebral perfusion is not likely to place the patient at increased risk of stroke.

D. In determining a stump pressure, the pressure measured just above the clamp is less than the pressure at the first branch point by an amount proportional to the distance to that branch point.

E. All of the above F. None of the above

Answer 9

B. Normal cerebral blood flow is 45-50 ml/100g/min, electroencephalography (EEG) changes are seen at 15-20 ml/100g/min, and cellular survival is threatened at 10-15 ml/100g/min.

Question 10

The transoral approach is APPROPRIATE in which of the following circumstances?

A. Malignant osseus neoplasm of the craniocervical junction

B. Benign midline extradural lesion extending from the lower third of the clivus to the upper two cervical vertebrae

C. Aneurysmof the upper third of the basilar artery

D. Patients with jaw opening of 20-25 mm

E. Schwannoma of a C 2 nerve root

Answer 10

B. Benign midline extradural lesion extending from the lower third of the clivus to the upper two cervical vertebrae

Question 11

A 44-year-old female has a six-month history of double vision and a two-month history of progressive headache and right periorbital pain. On neurologic examination, she has right oculomotor (III), trochlear (IV), and abduscens (VI) cranial nerve deficits and hypesthesia in the region of the right ophthalmic nerve (V 1 ). Imaging studies demonstrate an extra-axial homogenously enhancing mass arising from the medial wing of the sphenoid bone, involving the cavernous sinus and the anterior aspect of the gasserian ganglion. Based on the patient’s history, physical examination, and description of the imaging studies, the MOST LIKELY diagnosis is:

A. Meningioma

B. Temporal lobe glioma

C. Aneurysm of the cavernous portion of the internal carotid artery

D. Primary lymphoma

E. Metastatic adenocarcinoma

Answer 11

A. Meningioma

Question 12

A 44-year-old female has a six-month history of double vision and a two-month history of progressive headache and right periorbital pain. On neurologic examination, she has right oculomotor (III), trochlear (IV), and abduscens (VI) cranial nerve deficits and hypesthesia in the region of the right ophthalmic nerve (V 1 ). Imaging studies demonstrate an extra-axial homogenously enhancing mass arising from the medial wing of the sphenoid bone, involving the cavernous sinus and the anterior aspect of the gasserian ganglion. The BEST therapeutic options for this patient at this time is:

A. Fractionated whole-brain radiation therapy

B. Embolization

C. Observation

D. Stereotactic biopsy

E. Craniotomy

Answer 12

E. Craniotomy

Question 13

Regarding microsurgery of the cavernous sinus, which of the following statements is TRUE?

A. The trochlear nerve is thin and has a variable course and is the most commonly injured cranial nerve in this region.

B. The abduscens nerve travels medial to the internal carotid artery.

C. The trochlear nerve crosses the medial to the oculomotor nerve at the orbital aspect.

D. The abduscens nerve is normally located at the anterior end of the cavernous sinus between the second and third divisions of the trigeminal nerve.

E. The oculomotor nerve travels within Durello’s canal.

Answer 13

A. The trochlear nerve is thin and has a variable course and is the most commonly injured cranial nerve in this region.

Question 14

Regarding posterior fossa surgery in the sitting position, which of the following statements is TRUE?

A. A precordial Doppler ultrasound transducer may detect as little as 0.01 ml of intravascular air.

B. An acute increase in end-tidal CO2 is an effective means of detecting venous air embolism.

C. An acute increase in end-tidal (N2 ) gas is the most sensitive means of detecting entrained air in the venous system.

D. A decrease pulmonary artery pressure is an early warning sign of venous air embolism.

E. An electrocardiogram demonstrating left heart strain may be a late sign of large air emboli.

Answer 14

C. An acute increase in end-tidal (N2 ) gas is the most sensitive means of detecting entrained air in the venous system.

Question 15

. Depending on its size, a tumor of the jugular foramen may be removed through WHICH of the following approaches?

A. Lateral suboccipital

B. Combined suboccipital transtemporal

C. Presygmoid retrolabirinthine

D. Petrosal

E. All of the above

Answer 15

E. All of the above

Question 16

A new born child has seizure and overt heart failure. The child was well at the time of her birth. The anterior fontanelle is now full. A CT scan demonstrates hydrocephalus and a malformation (Figure 39). Based on the clinical history and CT finding, the NOST LIKELY diagnosis is:

A. Tectal glioma

B. Giant basilar aneurysm

C. Vein of Galen fistula

D. Hydrocephalus from obstructive pineal tumor

E. Brain abcess

Answer 16

C. Vein of Galen fistula

Question 17

A new born child has seizure and overt heart failure. The child was well at the time of her birth. The anterior fontanelle is now full. A CT scan demonstrates hydrocephalus and a malformation (Figure 39). Assuming this neonate’s condition becomes stable after medical treatment and has persistent borderline heart failure, OPTIMAL therapy would be:

A. Observation

B. Decadron, followed by surgical excision of the tumor

C. Surgical clipping of vein of Galrn aneurysm

D. Transvenous or transerterial embolization

E. Ventriculoperitoneal shunting

Answer 17

D. Transvenous or transerterial embolization

Question 18

A 5-year-old child present with seizure and has a grade III AVM (according to the Spetzler-Martin classification). Angiography demonstrates a 2.2 cm maximum diameter AVM in the right thalamus with drainage into the deep venous system. There has been no hemorrhage, but the child does have mild incoordination on the left arm and hand. You RECOMMEND the following treatment:

A. Surgery, with definitive removal of the entire AVM

B. Embolization, followed by surgery

C. Embolozation only, with follow up of angiography

D. No treatment; the risk of hemorrhage is low and surgical removal of the lesion carries significant risk

E. Stereotactic radiation

Answer 18

E. Stereotactic radiation

Question 19

A 50-year-old female present with vague complaints of neck pain, swallowing difficulties, visual complaints, and malaise. A cervical MRI demonstrates a syringomyelic cavity extending from C4 down into the conus medullaris, with downward displacements of cerebellar tonsils (Figure 40). The patient has mild gait difficulties and nystagmus. The contrast MRI does not demonstrate evidence of neoplasm in the cervical or thoracic chord. You ADVISE the following:

A. Percutaneous needling of the hydromyelic cavity

B. Terminal ventriculostomy: opening the distal part of the fluid sac, below the conus medullaris

C. Expectant treatment with surgery reserved for worsening of sign symptoms clearly related ot the syringomyelia

D. Suboccipital craniectomy, upper cervical laminectomies, followed duraplasty to decompress the Chiary malformation

E. Further radiographic studies

Answer 19

E. Further radiographic studies

Question 20

The following source of pain is LEAST likely to respond to dorsal column stimulation, assuming all other methods of pain control have failed

A. Post-amputation stump pain

B. Neuropathic pain from failed-back syndrome

C. Causalgia in the leg following gunshot injury

D. Ischemic pain resulting from inoperable vascular insufficiency

E. Angina

Answer 20

A. Post-amputation stump pain

Question 21

During surgery on the cervical spinal cord, somatosensory evoked potentials will NOT likely be affected by which of the following:

A. Hypercarbia

B. 2% of halothane

C. Fentanyl

D. Hypotension

E. Hypothermia

Answer 21

C. Fentanyl

Question 22

A pregnant woman with hypertension and proteinuria begins to have seizures. You are asked to treat her. You suggest WHICH of the following?

A. Eclampsia will cease with delivery. Therefore, deliver the fetus, do not give anticonvulsants.

B. Consider treatment after a thorough work-up, including the CT scan of the head.

C. Treat with the magnesium sulfate

D. Observe because no medication as yet tested reduces the seizure risk and morbid sequelae of eclampsia.

E. Use either diazepam, phenytoin, or magnesium because all three produce about the same beneficial effect in the treatment of seizures due to eclampsia.

Answer 22

C. Treat with the magnesium sulfate

Question 23

During routine physical examination, a healthy 65-year-old man is found to have a carotid bruit. He has hypertension, controlled with one antihypertension medication. Digital substraction angiography demonstrates 70% stenosis of the left internal carotid artery. You RECOMMEND:

A. No treatment in this asymptomatic patients

B. Expectant management, repeating angiogram in 6 months

C. Aspirin 325 per day

D. Aspirin 325 per day and elective carotid endarterectomy

E. Carotid percutaneous transluminal angioplasty

Answer 23

D. Aspirin 325 per day and elective carotid endarterectomy

Question 24

A 6-year-old boy is admitted to the hospital with an open depressed skull fracture at the vertex of he head. CT confirms the presence of displaced bone in the region of the superior sagittal sinus. Two hours following the injury, the child is admitted to the hospital. He is awake, and alert, but somewhat irritable, without focal neurological deficits. He is maintain in a sitting position but has a continual minimal seepage of blood and CSF from a3-cm scalp laceration. Very ild papilledema is seen by a neurology resident. There is no fever or meningismus. The hematocit is 36. You SHOULD:

A. Treat conservatively with antibiotics after closure of the skin laceration.

B. Operate immediately for elevation ef the depressed skull fracture and to eliminate CSF leakage and contamination.

C. Perform angiography or venography to identify the extent of sagittal sinus patency; if the sinus is noted to be preserved, treat the child conservatively with antibiotics and Diamox

D. Begin operative treatment when the entire operating team is ready to deal with potential massive hemorrhage

E. Treat conservatively with antibiotics and lumbar drainage

Answer 24

D. Begin operative treatment when the entire operating team is ready to deal with potential massive hemorrhage

Question 25

A newborn has a complicated forceps delivery. A 2 cm skin laceration occurs at the time of delivery and a “cephalhematoma” is noted in the parietal area. The laceration is sutured. Plain films confirm the presence of a linear skull fracture underlying the scalp hematoma. CT demonstrates a 4 mm depressed skull fracture; there is no intracranial hemorrhage. The scalp hematoma gradually expands. On the 5th day following delivery, this infant is increasingly toxic and a Gram-negative sepsis is diagnosed on the basis of blood cultures. The child becomes progressively more obtunded despite broad spectrum antibiotics and you are asked if any neurosurgical procedure is indicated. A very minimal coagulopathy is identified. The baby appears moribund. You RECOMMEND the following:

A. The coagulopathy should be corrected and the child observed.

B. This is a problem of septic shock. A lumbar puncture should be performed to assess the efficacy of the antibiotics being given.

C. Percutaneous needle aspiration of the scalp hematoma.

D. Sepsis is the underlying problem in this case. The risk of anesthesia and surgical exploration of the scalp is prohibitive. Continue intravenous antibiotics.

E. While the coagulopathy is being corrected, the child should be treated surgically with debridement of the scalp wound and exploration of the fracture site and underlying dura.

Answer 25

E. While the coagulopathy is being corrected, the child should be treated surgically with debridement of the scalp wound and exploration of the fracture site and underlying dura.

Question 26

146. An 82-year-old male is briefly admitted for evaluation of labyrinthitis. He has a Starr-Edwards aortic ball-valve prosthesis and takes Coumadin 2.5 mg per day. There is no valvular thrombosis. His neurological status is normal. Prior to his discharge, he slips and bumps the frontal area of the head. CT demonstrates soft tissue swelling in the scalp and generalized cerebral atrophy. His clinical status is unchanged, but the Coumadin is discontinued for three days following the fall. He is sent home on his usual anticoagulation regimen. A month later, he is found n hemiparetic but alert. Papilledema is present. He is rushed to the hospital. You obtain a repeat CT which demon- strates a subacute subdural hematoma causing approximately a 1 cm shift of midline structures. His partial throm- \ boplastin time is twice the control value. He remains clinically stable. You RECOMMEND:

A. immediate surgery using a large craniotomy for evacuation of the subdural hematoma, with Protamine given at the time of surgery

B. discontinuation of Coumadin, delivery of fresh frozen plasma, and surgery

C. immediate surgery with continuation of Coumadin postoperatively. A subdural drain is inserted during surgery. The craniotomy is deliberately made small to avoid excess bleeding.

D. discontinuation of Coumadin, delivery of fresh frozen plasma. Careful heparinization during the perioperative period with resumption of Coumadin after surgical evacuation of the subdural hematoma.

E. discontinuation of Coumadin. Careful heparinization with expectant management of the subdural he- matoma. Anticonvulsants given along with Decadron.

Answer 26

D. discontinuation of Coumadin, delivery of fresh frozen plasma. Careful heparinization during the perioperative period with resumption of Coumadin after surgical evacuation of the subdural hematoma.

Question 27

147. In patients who have demyelinating pathologies, such as multiple sclerosis or diabetic neuropathy, the conduction of action potentials along the axons can be slowed or blocked because of WHICH one of the following mechanisms?

A. Sodium channels are blocked when myelin is lost.

B. The myelin no longer conducts action potentials.

C. The time constant of the axon is shortened at the nodes of Ranvier.

D. Normal saltatory conduction is disturbed by regions having loss of myelin.

Answer 27

D. Normal saltatory conduction is disturbed by regions having loss of myelin.

Question 28

148. Which statement below CORRECTLY describes events at voltage sensitive channels in a nerve cell membrane?

A. Potassium ions flow out of the cell during the repolarization phase of the action potential.

B. Sodium ions flow from the inside of the membrane to the outside during the rising (depolarization) phase of the action potential.

C. Sodium conductance increases and remains at the increased level for as long as the membrane is depolarized from its resting voltage.

D. Potassium conductance increases then inactivates and remains inactivated for as long as the membrane is depolarized from its resting voltage.

Answer 28

A. Potassium ions flow out of the cell during the repolarization phase of the action potential.

Question 29

149. At WHICH LEVEL of the visual system is information transformed into linear segments and boundaries?

A. retina

B. pretectal area of the midbrain

C. superior colliculus

D. lateral geniculate nucleus

E. primary visual cortex

Answer 29

E. primary visual cortex

Question 30

A 40-year-old black female presents to the emergency room complaining of sudden onset of left sided periorbital pain and headache with the inability to open her left eye. Two weeks previously, she was seen in the emergency room complaining of severe diffuse headache and sent home with the diagnosis of tension headaches. On exam, she had no nuchal rigidity or photophobia. She was alert and oriented. She could not elevate her left eyelid or look medially. Her pupil was dilated and reacted minimally to light.

150. Based on the history and exam, WHICH of the following conditions is (are) in the differential diagnosis?

A. sarcoidosis

B. ischemic third cranial nerve palsy

C. posterior communicating artery aneurysm

D. ophthalmoplegic migraine

E. all of the above

Answer 30

E. all of the above