Vascular Flashcards
A 30-year-old woman is concerned about a difference in the size of her pupils. Neurological
examination shows that the right pupil measures 7 mm in diameter. It reacts to light slowly but fully,
after which it dilates slowly to its original size. Deep tendon reflexes are generally hypoactive.
Which of the following is the most likely diagnosis?
Answers:
A. Adie syndrome
B. Marcus Gunn pupil
C. Parinaud’s syndrome
D. Argyll Robertson pupil
E. normal physiologic response
A. Adie syndrome
The most likely diagnosis is Adie’s syndrome, also known as Holmes-Adie syndrome or Adie’s tonic pupil. This is common in women between the ages of 20 and 50 and is a benign syndrome in which the affected pupil is dilated with sluggish response to light and often associated with absent or diminished deep tendon reflexes. It is thought to be the result of denervation of the ciliary ganglion. Argyll Robertson pupil consists of light/near dissociation in which the light reflex is absent with preservation of accomodation and is often a result of neurosyphilis. A Marcus Gunn pupil is an afferent pupillary defect which can result from disease of the optic nerve or retina. Parinaud’s syndrome results from lesions of the tectum, such as pineal gland tumors, and causes light/near dissociation as well as vertical gaze paralysis, ptosis, lid retraction (Collier’s sign), and convergence-retraction nystagmus. The condition described in the patient is not a normal physiologic condition.
Which of the following muscles is innervated by the facial nerve?
Answers:
A. Orbicularis oris
B. Anterior belly of the digastric
C. Tensor veli palatini
D. Omohyoid
E. Masseter
A. Orbicularis oris
Orbicularis oris is innervated by the facial nerve. Anterior belly of digastic, masseter and tensor veli palatini are all innervated by the trigeminal nerve. Remember, it is the posterior belly of digastric which is innervated by the facial nerve. Omohyoid is innervated by ansa cervicalis.
After undergoing a right retrosigmoid acoustic neuroma surgery, the patient complains of metallic taste on the right side of the tongue. Injury to which of the following nerves (indicated by the white arrow in the photograph shown) is the most likely cause of this patient’s symptom?
A. inferior vestibular nerve
B. superior vestibular nerve
C. auditory nerve
D. nervus intermedius
E. facial nerve
D. nervus intermedius
The correct answer is the nervus intermedius. The chorda tympani is the terminal branch of the nervus intermedius and damage to the nervus intermedius can lead to alterations in taste sensation. The other listed nerves can all be identified in this image but are not indicated by the arrow and not likely to cause this patient’s symptoms.
The efferents from the carotid sinus project to the
Answers:
A. Spinal trigeminal nucleus
B. Nucleus tractus solitarius
C. Dorsal motor vagal nucleus
D. Nucleus ambiguus
E. Inferior salivatory nucleus
B. Nucleus tractus solitarius
Afferents from the carotid bulb are transmitted to the brainstem via the glossopharyngeal nerve where they terminate in the nucleus tractus solitarius. The nucleus ambiguus is an efferent nucleus for CN 9 and CN10. The dorsal motor vagal nucleus and inferior salivatory nuclei are parasympathetic efferent nuclei. The spinal trigeminal nucleus does receive CN IX afferents but they relate to somatic sensation of the posterior 1/3 of the tongue.
Which of the following clinical features of Horner syndrome would suggest that the dissection is proximal to the cervical carotid artery bifurcation?
Answers:
A. miosis, ptosis, and anhidrosis
B. miosis and anhidrosis but no ptosis
C. miosis only
D. miosis and ptosis but no anhidrosis
E. ptosis and anhidrosis but no miosis
A. miosis, ptosis, and anhidrosis
The classic incomplete Horner’s syndrome of an internal carotid artery dissection consists of miosis and ptosis but no anhidrosis since the sympathetic fibers innervating the facial sweat glands are found along the external carotid artery. However, if the dissection extended proximal to the bifurcation, the sympathetic fibers controlling the facial sweat glands may be affected and the patient may have a complete Horner’s syndrome.
During a carotid endarterectomy, blood pressure decreases from 170/90 mmHg to 70/40 mmHg following plaque removal but before arteriotomy closure; pulse remains 60/min. Which of the following is the most appropriate next step in management?
Answers:
A. Re-exploration of the artery to evaluate for further plaque
B. Observation
C. Administration of vasopressors
D. Fluid resuscitation
E. Carotid bulb lidocaine injection
E. Carotid bulb lidocaine injection
The correct answer is carotid bulb lidocaine injection. Plaque removal from the carotid sinus region during carotid endarterectomy can be associated with an alteration in baroreceptor function of the carotid sinus (innervated by CN IX). If hypotension and/or bradycardia occur, the carotid bulb can be anesthetized with 2-3 mL of 1% plain lidocaine. Given the hemodynamic instability, observation is not appropriate. Further plaque is not the cause of these symptoms and re-exploration of the artery for further plaque removal is not indicated. Fluid resuscitation and administration of vasopressors may be supportive but do not address the root cause of the symptoms.
While a patient is undergoing deep brain stimulation in the ventral intermediate (VIM) nucleus to treat essential tremor, test stimulation along the length of the tract causes strong paresthesias. This reaction indicates that the electrode is placed too far in which of the following directions?
A. posterior
B. superior
C. lateral
D. anterior
E. medial
A. posterior
When the lead is placed too posteriorly, the ventral caudate nucleus can be stimulated, causing persistent paresthesias. The lead should be repositioned anteriorly. Too medial placement can cause diplopia, eye deviation, nausea, and personality changes. Too posterior placement can cause paresthesia. Too superior placement will have no effect on tremor. Too anterior placement can cause tonic arm and face contractions.
Based on results of the North American Symptomatic Carotid Endarterectomy Trial, which of the
following is the absolute two-year risk reduction for ipsilateral stroke in patients with greater than
70% symptomatic stenosis who were treated with endarterectomy compared with those who
received the best medical therapy?
Answers:
A. 4%
B. 12%
C. 17%
D. 23%
E. 9%
C. 17%
According to the NASCET (North American Symptomatic Carotid Endarterectomy Trial), symptomatic (non-disabling stroke, TIA, amaurosis fugax) patients with high-grade (70%) stenosis of the ICA, as detected by non-invasive imaging, benefit from CEA. These patients obtained a 17% absolute reduction in risk of ipsilateral stroke at 2 years compared to those treated medically. The other answers listed are not correct.
A 30-year-old woman develops an intra-arterial thrombus in the parent vessel during an elective
aneurysm coiling procedure. Which of the following is the most appropriate pharmacotherapy?
Answers:
A. Aspirin
B. thrombectomy
C. IV tPA
D. IA verapamil
E. IV abciximab
IV abciximab
Abciximab, a IIb/IIIA inhibitor, inhibits platelet aggregation, which is thought to be the major cause of thrombi formation during aneurysm coiling. tPA activates plasminogen to plasmin, which cleaves the fibrin component of clots. Aspirin is an antiplatelet agent, but does not have a role in treating intra-procedural thrombi. Thrombectomy may be used as a rescue strategy, but does not represent a first-line treatment for intra-procedural thrombus formation. IA verapamil is typically used in the context of vasospasm and does not have a role in this situation.
A 23-year-old man with acute lymphoblastic leukemia and leptomeningeal tumor seeding is
evaluated because of headache. A T1-weighted axial MR image with contrast is shown. Which of
the following nerves is indicated by the arrow?
Answers:
A. Trochlear nerve
B. Oculomotor nerve
C. Trigeminal nerve
D. Facial nerve
E. Abducens nerve
Oculomotor nerve
Oculomotor nerve is the correct answer. The contrast-enhanced MRI demonstrates enhancement of the oculomotor nerve (CN III). Leptomeningeal disease, such as is described in this case, can result in asymptomatic enhancement of cranial nerves, which are usually small and nonenhancing. Isolated enhancement of CN III may also be seen in ophthalmoplegic migraine. The contrast-enhanced T1 axial image shown in the figure is at the level of the dorsal midbrain. This is the level of the cerebral aqueduct, oculomotor nuclei, and trochlear nuclei, and you can tell it is the oculomotor nerve due to its course anteriorly in the interpeduncular cistern. From the oculomotor nuclei, the fibers course anteriorly and laterally to exit the ventral aspect of the brainstem. The other cranial nerves listed in the answer choices are incorrect. The trochlear nerve (CN IV) can be recognized because its nucleus is in the dorsal midbrain, and is on the opposite side of the brainstem from the muscle it innervates. It is often difficult to see on MRI due to its small size. The trigeminal nerve (CN V) is the largest cranial nerve and emerges from the lateral pons, below the level of the figure. The motor roots can arise slightly superiorly and medially from the sensory roots, and then they course anteriorly to enter Meckel’s cave and travel along the lateral wall of the cavernous sinus. The abducens nerve (CN VI) courses from the dorsomedial pons, extending anterolaterally towards the pontomedullary junction, below the level of the figure. Th nerve extends towards Dorello’s canal and the cavernous sinus, where it travels next to the cavernous ICA and enters the superior orbital fissure. Pathologic enhancement of CN VI can be seen in the inflammatory condition Tolosa-Hunt syndrome. The facial nerve (CN VII) exits the brainstem from the ventrolateral surface at the level of the pontomedullary junction in the cerebellopontine angle, below the level of the figure. It courses laterally in the CPA to enter the internal auditory meatus.
A patient has a defect in the tegmen tympani and a subsequent recurrent CSF leak. A middle
fossa approach is performed to repair this leak. During elevation of the dura, a nerve is damaged.
Postoperatively, the patient reports a dry and scratchy eye ipsilateral to the side of the surgery. The
patient has no other neurological deficits. Which of the following nerves was injured during the
surgery?
Answers:
A. Ophthalmic nerve
B. Maxillary nerve
C. Mandibular nerve
D. Nasociliary nerve
E. Facial nerve
Ophthalmic nerve
The two clues in this question that point you towards the correct answer are the description of the procedure (middle cranial fossa approach for repair of a tegmen defect) and the neurological deficit (dry and scratchy eye likely due to corneal abrasion from loss of corneal sensation). The correct answer is the trigeminal nerve. The sensory root of the trigeminal nerve expands in the middle cranial fossa lateral to the cavernous sinus, where the trigeminal ganglion lies in Meckel’s cave in the temporal bone. The trigeminal ganglion then splits into the three divisions – the ophthalmic (V1), maxillary (V2) and mandibular (V3). V1 and V2 travel in the lateral wall of the cavernous sinus to exit the skull base via the superior orbital fissure and foramen rotundum, while V3 exits via the foramen ovale. During the dissection of dura off the temporal bone of the middle cranial fossa, in this case, it is likely that the ophthalmic division of the trigeminal ganglion has been damaged. Corneal sensation is supplied by the ophthalmic division of the trigeminal ganglion, with fibers traveling in the nasociliary nerve to the long ciliary nerve branches. The ophthalmic nerve splits into frontal, lacrimal, and nasociliary branches, which innervate skin and mucous membranes of the forehead, frontal and ethmoidal sinuses, upper eyelid, conjunctiva, cornea, and dorsum of the nose. Nasociliary nerve is not the correct answer. Although corneal sensory fibers travel in the nasociliary nerve, this nerve is not encountered in the middle cranial fossa dissection and would not be specifically damaged during the described surgery. It is a branch of the ophthalmic nerve after it exits the skull base at the superior orbital fissure. Facial nerve is not the correct answer. The facial nerve exits the intracranial space at the internal acoustic meatus, and passes through the temporal bone to exit the skull at the stylomastoid foramen. It is not particularly at risk during an extradural middle cranial fossa dissection. As explained above, the maxillary nerve (V2 division of the trigeminal nerve) and mandibular nerve (V3 division of the trigeminal nerve) are incorrect choices. These divisions are at risk during the extradural dissection, however they would not result in the corneal sensory deficit described in the question. Maxillary nerve damage would lead to loss of sensation over the lower eyelid, cheeks, maxillary sinus, nasal cavity, upper lip, superior palate, upper teeth and gingiva. Mandibular nerve damage would lead to loss of sensation of mucous membranes and floor of the oral cavity, external ear, lower lip, chin, anterior 2/3 of the tongue, and lower teeth. The mandibular nerve is the only division of CN V that has motor fibers, and innervates the muscles of mastication (medial pterygoid, lateral pterygoid, masseter and temporalis, anterior belly of digastric, mylohyoid, tensor veli palatini and tensor tympani).
A 9-year-old boy is evaluated for obstructive hydrocephalus secondary to a heterogeneously
enhancing pineal mass. The lesion will be treated using the infratentorial supracerebellar approach
to the pineal region and posterior third ventricle. Which of the following venous structures is most
likely to be sacrificed?
Answers:
A. vein of Galen
B. internal cerebral vein
C. basal vein of rosenthal
D. superior petrosal vein
E. precentral vein
precentral vein
During supracerebellar approaches to pineal region tumors, the precentral vein may be divided to help exposure. The internal cerebral vein, basal vein of rosenthal, and vein of galen cannot be safely divided. The superior petrosal vein is not visible in this approach.
During stereotactic biopsy of a lesion in the thalamus, a slow flow of blood under low pressure
emerges from the cannula. Which of the following is the most appropriate next surgical step?
Answers:
A. Emergency CT scan
B. Terminate procedure
C. Craniotomy
D. Complete biopsies
E. Irrigate through cannula
Irrigate through cannula
Symptomatic hemorrhage after stereotactic biopsy occurs in ~4.3% of cases. Bleeding encountered in the course of doing a stereotactic bopsy will generally stop with irrigation and observation. Prematurely removing the cannula in order to obtain a CT scan or a neurological examination may actually allow the accumulation of a hematoma that might otherwise been avoided. Doing a craniotomy and following the biopsy cannula tract will expose the patient to the risks of open surgery, generally including the transgression of deep neural structures. Nevertheless, bleeding from the cannula is a significant indication that no further specimens should be collected.
A 35-year-old woman is evaluated because of persistent, severe, right-sided retro-orbital pain that
came on suddenly two days ago. Three hours ago, she had an episode of transient right eye
blindness that lasted two minutes. The patient has no history of serious illness and takes no
medication. Examination shows a miotic pupil and ptosis on the right. Which of the following is the
most likely diagnosis?
Answers:
A. Ishchemic third nerve palsy
B. Internal carotid artery dissection
C. Central retinal artery occlusion
D. Transient ischemic attack
E. Migraine
Internal carotid artery dissection
The correct answer is internal carotid artery dissection (ICAD). ICAD classically presents with ipsilateral head, neck, or face pain, partial Horner’s syndrome, and resulting ischemic or retinal TIA or stroke. Transient monocular vision loss in ICAD can be from embolic or hypoperfusion causes. Importantly, as demonstrated in this example, the incomplete Horner’s syndrome is miosis and ptosis but no anhidrosis (these sympathetic fibers are found along the external carotid artery). Other symptoms of ICAD can include tinnitus and lower cranial nerve palsies (most commonly hypoglossal followed by the glosspharyngeal and vagus nerves). Migraine can present with ocular pain and visual symptoms but would not present with a partial Horner’s syndrome. Central retinal artery occlusion is an ischemic blockage of blood supply to the retina and is usually painless but can cause vision loss. An ischemic third nerve palsy, often from diabetes, presents with ptosis and eye movement abnormalities but does not demonstrate pupillary changes and is not painful; it also would not be expected to cause vision loss. A transient ischemic attack (TIA) could cause temporary blindness but would not be painful and would not present with a partial Horner’s syndrome.
A 79-year-old man presents with the spontaneous onset of episodic, lancinating pain along the right jaw. There are pain-free periods, but shocking pain can be triggered by changes in touch or chewing. MR imaging of the brain shows no mass lesions and a loop of the superior cerebellar artery compressing the right trigeminal nerve. Which of the following is the most appropriate initial treatment for this patient?
Answers:
A. Percutaenous Trigeminal Rhizotomy
B. Stereotactic Radiosurgery
C. Microvascular Decompression
D. Amitriptyline
E. Carbamazepine
Carbamazepine
The majority of patients experience complete or acceptable relief with carbamazepine treatment. Surgical or other interventional modes of management should be reserved for patients who fail medical management. The trigeminal nerve (V) is the fifth and largest of all cranial nerves, and it is responsible for detecting sensory stimuli that arise from the craniofacial area. The nerve is divided into three branches: ophthalmic (V1), maxillary (V2), and mandibular (V3); their cell bodies are located in the trigeminal ganglia and they make connections with second-order neurons in the trigeminal brainstem sensory nuclear complex. Ascending projections via the trigeminothalamic tract transmit information to the thalamus and other brain regions responsible for interpreting sensory information. One of the most common forms of craniofacial pain is trigeminal neuralgia. Trigeminal neuralgia is characterized by sudden, brief, and excruciating facial pain attacks in one or more of the V branches, leading to a severe reduction in the quality of life of affected patients. Trigeminal neuralgia etiology can be classified into idiopathic, classic, and secondary. Classic trigeminal neuralgia is associated with neurovascular compression in the trigeminal root entry zone, which can lead to demyelination and a dysregulation of voltage-gated sodium channel expression in the membrane. These alterations may be responsible for pain attacks in trigeminal neuralgia patients. The antiepileptic drugs carbamazepine and oxcarbazepine are the first-line pharmacological treatment for trigeminal neuralgia. Their mechanism of action is a modulation of voltage-gated sodium channels, leading to a decrease in neuronal activity. Although carbamazepine and oxcarbazepine are the first-line treatment, other drugs may be useful for pain control in trigeminal neuralgia. Among them, the anticonvulsants gabapentin, pregabalin, lamotrigine and phenytoin, baclofen, and botulinum toxin type A can be coadministered with carbamazepine or oxcarbazepine for a synergistic approach.
The mesencephalic nucleus of the trigeminal nerve receives input from which of the following
sources?
Answers:
A. Masseter spindle fibres
B. Forehead Pacinian corpuscles
C. Maxilla Ruffini corpuscles
D. Anterior 2/3 tongue taste buds
E. Alpha motor neurone to the masseter
Masseter spindle fibres
The role of the mesencephalic nucleus is control of chewing strength. It receives inputs from stretch receptors in the muscles of mastication and periodontal pressure sensation.Neurons in the trigeminal mesencephalic nucleus receive deep sensation (proprioception) from jaw-closing muscle spindles and periodontal ligaments and project primarily to the jaw-closing motoneuron pool (jaw-closing nucleus) of the trigeminal motor nucleus and to the supratrigeminal nucleus.
Division of the ansa hypoglossi during carotid endarterectomy can result in which of the following
adverse effects?
Answers:
A. Difficulty with speech and/or swallowing
B. Unilateral vocal cord paralysis
C. Sensory deficits over the parotid gland, angle of the mandible, and earlobe
D. Tongue deviation toward the affected side
E. Sagging of ipsilateral corner of the mouth
Difficulty with speech and/or swallowing
It can be necessary during a carotid endarterectomy to divide the ansa hypoglossi in order to mobilize the hypoglossal nerve to keep it out of harm’s way. The branches of the ansa hypoglossi innervate the infrahyoid muscles, which are very important in maintaining phonation and deglutition. Therefore, any injury to these muscles through their nerve supply could cause disturbance in phonation or swallowing. Unilateral vocal cord paralysis, tongue deviation, and sagging of the ipsilateral corner of the mouth can all occur after CEA from recurrent laryngeal nerve damage, hypoglossal nerve damage, and the marginal mandibular branch of the facial nerve damage, respectively. Sensory deficits over the parotid gland, angle of the mandible, and earlobe can be caused by damage to the transverse cervical nerve which usually lies near the inferior edge of the standard CEA incision.
Which of the following cranial nerves contains parasympathetic nerve fibers?
Answers:
A. Buccal nerve
B. Ophthalmic nerve
C. Chorda tympani nerve
D. Nerve to stapedius
E. Zygomatic nerve
Chorda tympani nerve
The correct answer is chorda tympani nerve. The chorda tympani nerve arises from the mastoid segment of the facial nerve, and carries afferent special sensation from the anterior two-thirds of the tongue via the lingual nerve, as well as efferent parasympathetic secretomotor innervation to the submandibular and sublingual glands. Nerve to stapedius is incorrect. This is a branch of the facial nerve that branches off in the mastoid segment in the facial canal before it exits the skull at the stylomastoid foramen. The nerve supplies the stapedius muscle in the ear. Damage to the nerve leads to hyperacusis, or hypersensitivity to loud noises. Zygomatic nerve is incorrect. This is a branch of the maxillary branch of the trigeminal nerve. It passes through the orbit and provides sensory innervation to the skin over the zygomatic and temporal bones. It does not carry parasympathetic fibers. Buccal nerve is incorrect. The buccal nerve is a sensory branch of the mandibular division of the trigeminal nerve. It innervates most of the buccal mucosa, inferior buccal gingiva, and skin over the top part of the lip. It does not carry parasympathetic fibers. The ophthalmic nerve is incorrect. This is the continuation of the first branch of the trigeminal nerve and provides sensory innervation of the face and scalp above the orbits. It contains sympathetic fibers supplying pupillary dilation, as well as ciliary body, iris, lacrimal gland, conjunctiva and cornea.
According to the 2018 guidelines published by the American Heart Association/American Stroke
Association (AHA/ASA) for the management of acute ischemic stroke, which of the following
statements is accurate?
Answers:
A. Pre-hospital infusion of magnesium has shown protective benefits in acute stroke.
B. The DEFUSE-3 trial provides evidence supporting mechanical thrombectomy between 6-24hours post-stroke onset.
C. In select patients stent retriver thrombectomy may beneficial for M2/M3 occlusions within 6 hours of onset.
D. Patients should not receive IV alteplase if they are being considered for mechanical thrombectomy.
E. Brain imaging studies should be performed within 60 minutes in atleast 50% of all patients considered for alteplase/thrombectomy.
In select patients stent retriver thrombectomy may beneficial for M2/M3 occlusions within 6 hours of onset.
Although the benefits are uncertain, the use of mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with acute ischemic stroke in whom treatment can be initiated (groin puncture) within 6 hours of symptom onset and who have causative occlusion of the MCA segment 2 (M2) or MCA segment 3 (M3) portion of the MCA. Brain imaging studies should be performed within 20 minutes in at least 50% of all patients considered for alteplase/thrombectomy. The DEFUSE-3 trial provides evidence supporting mechanical thrombectomy between 6-16 hours.The FAST-MAG trial did not show any benefits of pre-hospital magnesium.
The spinal trigeminal nucleus receives pain and temperature sensations from afferents with cell
bodies that are located in the
Answers:
A. Chief sensory nucleus
B. Gasserian ganglion
C. VPM nucleus
D. Geniculate ganglion
E. Spinal trigeminal tract
Gasserian ganglion
Cell bodies for both pain/temperature and discriminative touch reside in the Gasserian ganglion as bipolar cells. Axons project proximally to synapse on the spinal trigeminal nucleus. Second order neurons from the spinal trigeminal nucleus run in the anterior trigemino-thalamic tract to the VPM nucleus of the thalamus and third order nucleus from the thalamus project to the sensory cortex.
A 4-week-old infant, who was born at 26 weeks’ gestation, presents with a grade IV intraventricular
hemorrhage and posthemorrhagic hydrocephalus. Weight is 1.2 kg (2.2 lbs). Physical examination
shows stable vital signs, a normal head circumference growth curve, and soft anterior fontanel.
Which of the following is the most appropriate initial management of the hydrocephalus?
Answers:
A. Serial Lumbar Punctures
B. Observation
C. Ventriculosubgaleal Shunt
D. Ventricular Puncture
E. Ventriculoperitoneal Shunt
Observation
The correct answer is observation. The patient’s head circumference, fontenelle, and vital signs are all reassuring for non-symptomatic hydrocephalus at this time. Interventions all carry risks and preterm infants such as this patient especially have a higher risk of infection after interventions. If the patient should develop symptomatic hydrocephalus, serial lumbar punctures can be used to stabilize the head circumference and clinical status and potentially reduce need for eventual surgical intervention.
The use of an endovascular flow diverter is approved by the FDA for the treatment of aneurysms
with which of the following characteristics?
Answers:
A. distal MCA aneurysm
B. proximal ACA aneurysm
C. large ophthalmic artery aneurysm
D. unruptured anterior communicating artery aneurysm
E. mycotic aneurysm
large ophthalmic artery aneurysm
Endovascular flow diverters (specifically the pipeline embolization device) were initially approved by the FDA for endovascular treatment of adults (age 22 and above) with large wide necked intracranial aneurysms in the ICA from the petrous to superior hypophyseal segments. It is not FDA approved for distal MCA aneurysms, mycotic aneurysms, or ACA/AComm aneurysms.
A patient undergoes resection of a tumor in the pineal region using the supracerebellar approach.
Which of the following veins is most likely to be divided during the procedure?
Answers:
A. basal vein of rosenthal
B. vein of Galen
C. internal cerebral vein
D. precentral vein
E. superior petrosal vein
precentral vein
During supracerebellar approaches to pineal region tumors, the precentral vein may be divided to help exposure. The internal cerebral vein, basal vein of rosenthal, and vein of galen cannot be safely divided. The superior petrosal vein is not visible in this approach.
Lesions in which of the following locations are most likely to result in denial of blindness (Anton
syndrome)?
Answers:
A. lateral geniculate nucleus
B. bilateral occipital lobe
C. dominant parietal lobe
D. corpus callosum
E. V5 visual cortex
bilateral occipital lobe
A patient with cortical visual impairment (or cortical blindness) may deny that there is any visual problem; this is called Anton syndrome. Anton syndrome is most common with bilateral occipital infarctions. The V5 cortex represents the motion selective visual cortex, and its lesioning can produce akinetopsia. Lesion of the corpus callosum can result in various disconnection syndromes. Lesioning of the dominant parietal lobe can cause Gerstmann’s Syndrome. Lesioning of the lateral geniculate nucleus results in a homonymous hemianopia.
During implantation of a deep brain stimulator lead to treat intractable tremor, test stimulation of
1.0.V at the target site induces significant, unrelenting paresthesias involving the hand. In which of
the following directions should the lead be repositioned?
Answers:
A. superior
B. anterior
C. posterior
D. lateral
E. medial
anterior
When the lead is placed too posteriorly, the ventral caudate nucleus can be stimulated, causing persistent paresthesias. The lead should be repositioned anteriorly. Too medial placement can cause diplopia, eye deviation, nausea, and personality changes. Too posterior placement can cause paresthesia. Too superior placement will have no effect on tremor. Too anterior placement can cause tonic arm and face contractions.
In the intraoperative microscopic image of the right cerebellar pontine angle shown, the black
diamond is on the vestibulocochlear nerve. Which of the following structures is indicated by the
white arrow?
Answers:
A. Trigeminal nerve
B. Abducens nerve
C. Glossopharyngeal nerve
D. Vagus nerve
E. Facial nerve
Trigeminal nerve
The key to this question is correctly orientating yourself to the side of the head and remembering the anatomy of the cerebellopontine angle. The correct answer is the trigeminal nerve. This nerve is typically large, well visualized by the standard retrosigmoid approach, and often compressed by the SCA causing trigeminal neuralgia. The petrosal vein is seen in this image overlying the inferior portion of the nerve. The facial nerve is not the correct answer. The facial nerve lies with the vestibulocochlear nerve and exits at the porus acousticus. The structure indicated is clearly superior to the VII/VIII bundle. The glossopharyngeal nerve is not the correct answer. The glossopharyngeal nerve is located caudal to the vestibulocochlear nerve, so the orientation of the image and knowing that it is a right sided craniotomy tells you this is the wrong answer. The glossopharyngeal nerve may be compressed by PICA, causing glossopharyngeal neuralgia. The vagus nerve is not the correct answer. This nerve is located even more caudal to the vestibulocochlear nerve than the glossopharyngeal nerve. The abducens nerve is not the correct answer. The abducens nerve is not easily visualized by the standard retrosigmoid craniotomy as it lies deeper (i.e. more anterior) and just superior to the vestibulocochlear nerve.
Which of the following is most likely to result from injury to the trochlear (IV) nerve?
Answers:
A. Diplopia worse on upgaze
B. Diplopia worse when looking away from the injured side
C. Head tilt away from the injured side
D. Intorsion
E. Head tilt towards the injured side
Head tilt away from the injured side
The trochlear nerve innervates the superior olique muscle whose action is intorsion, depression in the adducted position, and lateral rotation. Patients compensate by tilting the head towards the unaffected side.
Which of the following is a common complication of a lesion in the subthalamic nucleus?
Answers:
A. choreoathetosis
B. rigidity
C. tremor
D. bradykinesia
E. hemiballismus
hemiballismus
The correct answer is hemiballismus. Hemiballism is thought to be a result of damage to the normal function of the subthalamic nucleus (STN) which leads to excessive dopaminergic activity. Normally, the STN has an excitatory effect on the internal segment of the globus pallidus (GPi); with this effect decreased, the GPi output decreases as well. Since the GPi has an inhibitory effect on the thalamus, the injury to the STN ultimately reduces inhibition on the thalamus, thus increasing dopaminergic activity. Choreoathetosis is a dyskinetic side effect of carbidopa-levodopa. Bradykinesia, rigidity, and tremor are all features of Parkinson’s disease.
The image shown is obtained during removal of a pineal tumor (T) via the infratentorial approach in
a 25-year-old man. Which of the following venous structures is designated by the asterisk?
A. basal vein of Rosenthal
B. vein of galen
C. internal cerebral vein
D. precentral cerebellar vein
E. internal occipital vein
precentral cerebellar vein
This vessel is the precentral cerebellar vein, which may be sectioned during the infratentorial supracerebellar appraoch to the pineal gland. The internal occipital vein, basal vein of rosenthal, and internal cerebral veins are not midline structures. The vein of galen would be located antero- superior to this highlighted structure.
A 45-year-old female smoker with no significant medical history presents to the emergency department two hours after acute onset of right hemiparesis and aphasia. Neurological examination is fluctuating in severity. Non-contrast CT scan of the head is normal. Which of the following imaging studies should be obtained next?
Answers:
A. MRI cervical spine
B. lumbar puncture
C. digital substraction angiography
D. MRI brain without contrast
E. CT angiography of the head and neck
CT angiography of the head and neck
A non contrast CT scan will not demonstrate hyperacute stroke, therefore a contrasted vessel imaging study is necessary in this situation, such as CT angiogram. This is the fastest modality to identify if a patient may be a candidate for treatment. An MRI of the brain (not C-spine) and digital subtraction angiography may be appropriate after a CTA. A lumbar puncture is not indicated.
The primary synapse for pain and temperature in the trigeminal nerve is in the
Answers:
A. Trigeminal (Gasserian) ganglion
B. Chief sensory nucleus
C. Venteral posteriomedial nucleus
D. Mesencephalic nucleus
E. Spinal trigeminal nucleus
Spinal trigeminal nucleus
Pain and temperature sensation of the face is transmitted via the spinal trigeminal system. The first order neurons are pseudounipolar, with their cell bodies in the Gasserian ganglion. These neurons enter the pons but travel inferiorly to synapse in the spinal trigeminal nucleus. The second order neurons form the trigeminal thalamic tract to the VPM nucleus and the third order neurons connect the thalamus to the sensory cortex.
The presence of a Marcus Gunn pupil in association with multiple sclerosis indicates that the
lesion is in which of the following locations?
Answers:
A. Superior colliculus
B. Chiasm
C. Optic radiation
D. Visual cortex
E. Optic nerve
Optic nerve
A Marcus Gunn pupil (relative afferent pupillary defect or RAPD) is illicited by a swinging flashlight test, and manifests as aberrant pupillary dilatation upon light stimulation of the ipsilateral eye. This results from impaired action of the pupillary light reflex, a signaling circuit wherein stimulation of the retina triggers discharges along the optic nerve, ipsilateral optic tract, and bilateral pretectal nuclei, which then synapse upon the bilateral CNIII and ciliary ganglion, resulting in iris contraction. The optic radiation, superior colliculus, chiasm, and visual cortex are not part of this arc.
When the foramen of Monro is visualized through a transcallosal approach, which of the following
structures forms the anterior and superior margin of the foramen?
Answers:
A. Caudate
B. Thalamus
C. Choroid plexus
D. Corpus callosum
E. Fornix
Fornix
The anterior and superior margin of the foramen of monro is formed by the fornix. The caudate forms the lateral wall of the frontal horn of the lateral ventricle. The thalamus forms the inferior and lateral wall of the body of the lateral ventricle. The corpus callosum is situated superior to the foramen of Monro. The choroid plexus is situated at the posterior inferior margin of the foramen.
A patient has a left hemiparesis, right-sided headaches, and Horner’s syndrome on the right.
Which of the following is the most likely diagnosis?
Answers:
A. Migraine
B. Hypothalamic Infarct
C. Internal Carotid Artery Dissection
D. Apical Lung Tumor
E. Lateral Medullary Infarct
Internal Carotid Artery Dissection
The correct answer is internal carotid artery dissection. ICA dissection classically presents with ipsilateral head, neck, or face pain, partial Horner’s syndrome, and resulting ischemic (or retinal) stroke. The headache is a unilateral headache on the side of the dissection and the incomplete Horner’s syndrome is miosis and ptosis but no anhidrosis (these sympathetic fibers are found along the external carotid artery). Other symptoms can include tinnitus and lower cranial nerve palsies (most commonly hypoglossal followed by the glosspharyngeal and vagus nerves). Lateral medullary infarct presents as Wallenberg syndrome which includes Horner’s syndrome, vertigo, dysphagia, nystagmus, and facial weakness. Apical lung tumors can cause a Horner’s syndrome but are unlikely to cause the other symptoms listed. While migraines can occur with hemiplegia, Horner’s syndrome does not occur. A hypothalamic infarct can cause an ipsilateral Horner syndrome and contralateral hemiparesis and contralateral decreased sensation but is unlikely to have associated headache.
A 65-year-old woman is evaluated for unilateral loss of the nasal visual field. An abnormality in
which of the following parts of the visual pathway is the most likely cause of this patient’s
condition?
Answers:
A. Lateral geniculate nucleus
B. Occipital cortex
C. Optic tract
D. Optic chiasm
E. Optic nerve
Optic nerve
The patient in the question stem is experiencing unilateral partial visual field deficit (loss of nasal field) due to compression of the lateral portion of the optic nerve. The optic nerve is the correct answer. Lateral compression of the optic nerve may be caused by a suprasellar aneurysm, ischemia or trauma. Although this is in practice a rare occurrence, you can work out the correct answer in a relatively straightforward manner keeping in mind the visual pathway from the retina through to the occipital cortex. Remember, any unilateral visual field loss is due to a prechiasmatic lesion. Anything at the chiasm or later in the visual pathway will lead to a homonymous deficit. In addition, lesions of the very posterior part of the optic nerve as it enters the chiasm can cause a junctional scotoma where there is contralateral superior temporal field loss in addition to ipsilateral vision loss. Lesions of the optic chiasm typically cause a bitemporal field loss. Lesions of the optic tract typically cause a contralateral homonymous defect. Lesions in the temporal lobe cause a contralateral superior hemianopic defect, whereas lesions in the parietal lobe cause a contralateral homonymous inferior hemianopic defect, which usually extends above the midline into the superior quadrant. Lesions of the lateral geniculate nucleus will cause contralateral homonymous sectoranopias – you can observe a hemianopic defect in the middle part of the contralateral hemifield, or in the outer (upper and lower) parts of the contralateral hemifield. Occipital cortical lesions will cause homonymous scotomas or homonymous macular-sparing hemianopias.
An intraoperative photograph of the porus acusticus from a suboccipital approach is shown.
Compression of the nerve indicated by the arrow can lead to which of the following clinical
conditions?
Answers:
A. Tinnitus and vertigo
B. Pain deep in the ear
C. Electric pain in the gums and teeth
D. Stabbing pain in the tonsils and base of the tongue
E. Pain in the external auditory canal
Pain deep in the ear
The nerve hook in the Figure is separating the facial nerve from the vestibulocochlear nerve, and the white arrow is indicating the nervus intermedius. Compression of the nervus intermedius can lead to geniculate neuralgia, which manifests clinically as intermittent episodes of pain deep in the ear that last for seconds or minutes and are often triggered by sensory or mechanical stimuli at the posterior wall of the auditory canal. Even if you have not heard of geniculate neuralgia, which is indeed very rare, you can work out what the symptoms of compression of the nerve might be based on your knowledge of the nervus intermedius and its function. The nervus intermedius derives fibers from the superior salivatory nucleus and carries parasympathetic fibers to the lacrimal and nasopalatine glands. It transmits sensory information from the tongue, skin of the nose, and concha of the external ear. Sectioning of the nervus intermedius can cause decreased sensation over the ear, part of the EAC and over the mastoid process. Stimulation of the nerve can cause referred pain to the ear, helping to explain the symptoms of geniculate neuralgia. Pain in the external auditory canal is not the correct answer. This part of the ear is innervated by sensory cutaneous nerves from the greater auricular nerve and the lesser occipital nerves, branches of the cervical plexus. Stabbing pain in the tonsils and base of the tongue is not the correct answer. This describes the symptoms of glossopharyngeal neuralgia, which can also cause pain in the back of the throat and middle ear. It is typically occult, but may be caused by compression of the glossopharyngeal nerve by PICA, or by an abnormally long styloid process. Electric, shooting pain the teeth and gums is not the correct answer. This describes trigeminal neuralgia. When there is an arterial compression, it is most commonly caused by the superior cerebellar artery. Tinnitus and vertigo is not the correct answer. These symptoms are caused by vestibulocochlear neuralgia, which may be caused by compression by a loop of the superior cerebellar artery.
A 49-year-old man is evaluated because of longstanding headaches refractory to nonsteroidal
agents. T1-weighted sagittal (Figure 1), T2 FLAIR axial (Figure 2), and T2-weighted axial (Figure
3) MR images depict an intracranial mass lesion. Which of the following is the most appropriate
management?
Answers:
A. CSF Diversion
B. Lumbar Puncture
C. Stereotactic Radiosurgery
D. Surgical Resection
E. Observation
Observation
The correct answer is observation with no management necessary. The MRI demonstrates a benign intracranial lipoma, characterized by a midline lesion with signal characteristics of fat on MRI. Hydrocephalus may develop requiring a lumbar puncture for diagnosis and ultimately CSF diversion; however, this scan shows no evidence of hydrocephalus and ultimately these lesions rarely require surgical intervention.
A 73-year-old man is evaluated for endovascular treatment of epistaxis. Obtaining a control
angiogram of both the internal carotid artery and external carotid artery is imperative for which of
the following reasons?
Answers:
A. to assess pre-embolization flow dynamics
B. to fully evaluate for source of the hemorrhage
C. to evaluate for anastomotic feeding branches
D. to rule out concomitant intracerebral aneurysm
E. to assess for alternative ECA etiology
to evaluate for anastomotic feeding branches
The majority of nosebleeds come from Kiesselbach’s plexus which is the site of anastomosis for both ECA and ICA branches. Although important, the other answer choices listed do not specifically answer the question. Careful evaluation of the preembolization angiographic images to exclude dangerous collaterals and anastomosis, along with careful embolization technique, should make embolization of routine epistaxis a safe procedure. However, it is important to review the final images carefully for any evidence of intracranial embolization and to perform a neurological examination as soon as possible after completing embolization.
Which of the following phenomena observed during activation of a thalamic deep brain stimulation
electrode indicates that the lead is positioned too laterally?
Answers:
A. paresthesia
B. tonic contraction of arm and face
C. amelioration of tremor
D. eye deviation
E. pain in contralateral arm
tonic contraction of arm and face
When the lead is placed too laterally, the internal capsule is stimulated, causing tonic arm and face contractions. The lead should be repositioned medially. Too medial placement can cause diplopia, eye deviation, nausea, and personality changes. Too posterior placement can cause paresthesia. Too superior placement will have no effect on tremor. Too anterior placement can cause tonic arm and face contractions.
Which of the following patients would be expected to benefit the most from a carotid
endarterectomy?
Answers:
A. 74 year old male with 65% carotid stenosis and ipsilateral cerebral hemisphere transient
ischemic attack within 120 days
B. 65 year old female with 75% carotid stenosis with ipsilateral retinal transient ischemic
attack within 120 days
C. 55 year old male with 60% carotid stenosis who is asymptomatic
D. 68 year old female with carotid stenosis of 45% and history of mild ipsilateral stroke in
prior 120 days
E. 71 year old male with 80% carotid stenosis with contralateral retinal transient ischemic
attack within 120 days
65 year old female with 75% carotid stenosis with ipsilateral retinal transient ischemic attack within 120 days
The correct answer is the 65 year old with the symptomatic cartoid stenosis of >70%. Endarterectomy in patients with symptomatic moderate carotid stenosis of 50 to 69 percent yielded only a moderate reduction in the risk of stroke. Decisions about treatment for patients in this category must take into account recognized risk factors, and exceptional surgical skill is obligatory if carotid endarterectomy is to be performed. Patients with stenosis of less than 50 percent did not benefit from surgery. Patients with severe stenosis (≥70 percent) had a durable benefit from endarterectomy at eight years of follow-up compared to aspirin alone. Patients with hemispheric or retinal transient ischemic attacks or mild cerebrovascular accident within 120 days and ipsilateral stenosis ≥70% should receive carotid endarterectomy.
The cell bodies of the primary neurons in the olfactory system lie in which of the following
locations?
Answers:
A. Olfactory tract
B. Olfactory stria
C. Olfactory bulb
D. Olfactory cortex
E. Olfactory epithelium
Olfactory epithelium
The first order neurons of the olfactory system are bipolar neurons in the olfactory epithelium. They have axons which project inferiorly into the nasal cavity and also superiorly through the cribiform plate to synapse on the olfactory bulb. The olfactory bulb has the cell bodies of the second order neurons whose axons form the olfactory tracts.
Which of the following arteries supplies the dorsal and ventral nerve roots of the spinal cord?
Answers:
A. vertebral arteries
B. posterior spinal arteries
C. arterial vasocorona
D. anterior spinal arteries
E. radicular arteries
radicular arteries
The spinal branch of each intercostal artery divides into dural and radicular arteries after penetrating the outer dural layers covering the nerve roots in the intervertebral foramina. The dural arteries supply blood to the spinal and nerve root dura, and the radicular arteries supply the anterior and posterior nerve roots. At some levels, the segmental artery also gives rise to a medullary branch that penetrates the nerve sheath dura, travels along the nerve roots, and supplies the anterior spinal artery or one of the paired posterolateral spinal arteries. Vertebral arteries, arterial vasocorona, and anterior/posterior spinal arteries may directly or indirectly supply the spinal cord but do not answer the question specifically.
A 38-year-old man presents with the contrast-enhanced T1-weighted axial MR image shown.
Which of the following signs or symptoms is most likely to be found on past medical history and
physical examination?
Answers:
A. diplopia
B. hearing loss
C. dysphagia
D. headache
E. ataxia
hearing loss
The image demonstrates a left-sided jugular foramen schwannoma. Schwannomas located at the jugular foramen may arise from cranial nerves IX–XI. Clinical presentation of jugular foramen schwannomas depends on the tumour’s extension rather than corresponding to the nerve of origin. Tumors like the one pictured with intracranial extension typically present with hearing loss and compromise of CN VIII. Dysphagia and ataxia are seen with jugular foramen schwannomas, but occur less often than hearing loss. Large tumors can present with signs of intracranial hypertension such as headache. Diplopia is rarely seen as a clinical sign of jugular foramen schwannomas.
Which of the following anatomic structures is indicated by the arrow in the axial MR image shown?
Answers:
A. Cavernous sinus
B. Foramen ovale
C. Meckel’s cave
D. Foramen rotundum
E. Inferior orbital fissure
Meckel’s cave
The arrow in the T2-weighted axial MRI in the figure is pointing to Meckel’s cave. Meckel’s cave (or the trigeminal cave) is a CSF-containing dural pouch in the middle cranial fossa. It is situated posterolateral to the cavernous sinus, and the trigeminal ganglion sits at the base of Meckel’s cave along with the petrous apex of the petrous temporal bone. Meckel’s cave acts as a conduit between the prepontine cistern and the cavernous sinus, through which the trigeminal nerve runs. It is a major pathway of perineural spread of neoplasms. The cavernous sinus is not the correct answer. On MRI, the cavernous sinus can be seen medial to the CSF space that the arrow is pointing to. It is bounded superiorly by dura connecting the anterior and middle clinoid processes; anteriorly by the superior orbital fissure and orbital apex; posteriorly by the petrous apex; medially by the sphenoid bone; and laterally by dura of the medial part of the middle cranial fossa. The foramen ovale is not the correct answer. The foramen ovale is not easily seen on an axial MRI. It is located at the posterior base of the greater wing of the sphenoid bone at the medial part of the middle cranial fossa, and transmits the mandibular division of the trigeminal nerve, accessory meningeal artery, emissary veins, and otic ganglion. The foramen rotundum is not the correct answer. The foramen rotundum, like ovale, is not easily seen on an axial T2-weighted MRI (it is easier seen on coronal reconstructions or CT). The foramen rotundum lies inferomedial to the superior orbital fissure at the base of the greater wing of the sphenoid bone. It is identifiable on coronal images by its characteristic oblique path from superomedial to inferolateral, joining the middle cranial fossa with the pterygopalatine fossa. It contains the maxillary branch of the trigeminal nerve, the artery of the foramen rotundum, and emissary veins. The inferior orbital fissure is not the correct answer. The IOF lies in the floor of the orbit inferior to the SOF and is bounded by the greater wing of the sphenoid, the maxilla, the orbital process of the palatine bone, and the zygomatic bone. It contains the infra-orbital and zygomatic nerves (branches of V3), inferior ophthalmic vein, emissary veins, infra-orbital artery, and orbital ganglionic branches of the pterygopalatine ganglion.
The cadaver dissection shown depicts the lower cranial nerves on the left side. The sectioning of
which of the following nerves (A-E) is most likely to result in hoarseness, dysphagia, and an
increased risk of aspiration?
Answers:
A. A
B. B
C. C
D. D
E. E
C
The figure depicts the exposure of the left lower cranial nerves as they exit the skull base via their respective foramina. The nerves have been sectioned at the brainstem so you can see their course in the pontomedullary sulcus and at the exiting foraminae. From top to bottom: A is the VII/VIII complex; B is the glossopharyngeal nerve (CN IX); C is the rootlets of the vagus (CN X); D and E are the cranial and spinal rootlets of the accessory nerve (CN XI). Of these, the nerve that, if sectioned, would result in hoarseness, dysphagia, and an increased risk of aspiration is the vagus nerve. C is the correct choice. Other symptoms of vagus nerve damage includes loss of gag reflex, ear pain, and arrythmias. The other answer choices are incorrect. Sectioning of the glossopharyngeal nerve would lead to swallowing dysfunction, impairment of taste and sensation over the posterior one-third of the tongue, loss of gag reflex, and parotid dysfunction. The cranial rootlets of the accessory nerve travel for a short distance with the accessory nerve in the jugular foramen, but then go on to contribute a small number of fibers to the vagus nerve. Their precise contribution to the pharyngeal muscles is debated and is likely minor, so it it not the best answer here. Sectioning of the spinal rootlets of the accessory nerve would cause shoulder pain, trapezius palsy, and winging of the scapula.
In the contrast-enhanced CT image shown, the foramen indicated by the tip of the arrow contains
which of the following?
A. Jacobson’s nerve
B. glossopharyngeal nerve
C. Carotid artery
D. Meningeal branch of the ascending pharyngeal artery
E. Hypoglossal nerve
Hypoglossal nerve
The axial slice through the CT in the figure indicates the hypoglossal canal. Of the answer choices provided, the only structure that passes through the hypoglossal canal is the hypoglossal nerve, which is the correct answer. The hypoglossal canal is located between the occipital condyle and the jugular tubercle and runs from posteromedial to anterolateral. It contains the hypoglossal nerve, which goes on to innervate the genioglossus, hyoglossus, styloglossus and palatoglossus muscles. The jugular foramen contains the glossopharyngeal nerve, Jacobson’s nerve (which is the tympanic branch of the glossopharyngeal nerve supplying the tympanic membrane), and meningeal branches of the ascending pharyngeal artery. It also contains the jugular bulb, the vagus and accessory nerves. The carotid artery passes through the carotid canal which is located superomedial to the jugular foramen.
In the intraoperative photograph following a right pterional craniotomy shown, which of the
following is indicated by the arrow?
Answers:
A. Internal Carotid Artery
B. Pituitary Stalk
C. Ophthalmic Artery
D. Optic Nerve
E. Optic Chiasm
Pituitary Stalk
The correct answer is the pituitary stalk, which can be seen behind CN II.
A 67-year-old woman with a remote history of intracranial hemorrhage is brought to the emergency
department five hours after the onset of left hemiparesis. CT scan of the head shows no evidence
of hemorrhage. A digital subtraction arteriogram is shown. Which of the following is the most
appropriate next step?
Answers:
A. mechanical thrombectomy
B. aspirin and statin
C. CT Angiography
D. IV TPA
E. MRI Brain
mechanical thrombectomy
Although recent guidelines have been updated to remove history of intracranial hemorrhage as an absolute contraindication to TPA usage, this patient is outside the window for TPA and should receive mechanical thrombectomy. Although the benefits are uncertain, the use of mechanical thrombectomy with stent retrievers may be reasonable for carefully selected patients with acute ischemic stroke in whom treatment can be initiated (groin puncture) within 6 hours of symptom onset and who have causative occlusion of the MCA segment 2 (M2) or MCA segment 3 (M3) portion of the MCA. Brain imaging studies should be performed within 20 minutes in at least 50% of all patients considered for alteplase/thrombectomy. The DEFUSE-3 trial provides evidence supporting mechanical thrombectomy between 6-16 hours. CTA, MRI brain, and ASA/statin may be performed or given after thrombectomy.
By using a telovelar approach instead of splitting the vermis to approach the tumor in the MR
image shown, which of the following postoperative complications may be avoided?
Answers:
A. shunt dependency
B. cerebellar mutism
C. cranial nerve palsy
D. hemorrhage
E. CSF leak
cerebellar mutism
Surgical approaches to the fourth ventricle include the transvermian approach, where the vermis is split, and the telovelar approach, which involves lifting the cerebellar tonsils and opening of the tela choroidea and inferior medullar velum to access the fourth ventricle. Transvermian approaches suffer from relatively high rates of cerebellar mutism (~15-25%) and disequilibrium, likely a consequence of damage to the cerebellar nuclei. In contrast, most studies show that these complications are less common in telovelar appraoches, although this point remains debated by some clinicians. Transvermian approaches do offer better views of the medial and super part of the fourth ventricle. Cranial nerve palsy is a risk in both approaches (~14%). CSF leak and hemorrhage rates are small (2-4%) and similar between approaches.
The intraoperative image shown is from a patient undergoing a right pterional craniotomy. Which of
the following structures is designated by the asterisk?
Answers:
A. optic nerve
B. middle cerebral artery
C. pituitary stalk
D. olfactory nerve
E. anterior cerebral artery
pituitary stalk
The pituitary stalk is visible behind the optic chiasm in this image. The optic nerve is the large white structure in the fore of the field. The anterior cerebral artery would be located superior to the optic nerve rather than behind it. The middle cerebral artery would be located laterally. The olfactory nerve is more medially located and would be against the skull base rather than extending downward.
Which of the following is the most appropriate treatment for the symptomatic carotid-cavernous
fistula in the digital subtraction angiogram shown?
Answers:
A. open operative intervention
B. transarterial coiling
C. transvenous coiling
D. carotid sacrifice
E. flow diversion
transvenous coiling
This is an indirect Carotid-cavernous fistula (CCF) for which the treatment is transvenous coiling. Flow diversion, transarterial coiling, carotid sacrifice and open operative intervention are not first line treatments. Direct CCFs result from a tear in the intracavernous carotid artery. Indirect CCFs generally occur spontaneously and cause more subtle signs. Direct CCFs, which typically have high flow, usually present with ocular-orbital venous congestive features and cephalic bruit. Indirect CCFs, which typically have low flow, present with similar but more muted clinical features. Direct CCFs are always treated with endovascular methods. The goal is to occlude the fistula but preserve the patency of the internal carotid artery (ICA). Agents include detachable coils or liquid embolic agents delivered transarterially or transvenously. Arterial porous or covered stents are often used adjunctively. In rare cases, the ICA must be occluded. Indirect CCFs are only treated if symptoms are intractable or intolerable or if vision is threatened. The goal is to interrupt the fistulous communications and decrease the pressure in the cavernous sinus.
An intraoperative photograph through an operating microscope from a left pterional approach is
shown. Which of the following deficits would occur from complete transection of the structure
identified at the level indicated by the black line?
Answers:
A. Complete vision loss of the left eye with inferior temporal field loss in the right eye
B. Complete vision loss in left eye
C. Complete vision loss in the left eye with partial nasal field loss in the right eye
D. Right homonymous hemianopsia
E. Bitemporal hemianopsia
Complete vision loss in left eye
The figure demonstrates the view of the ipsilateral (left) optic nerve and chiasm from a pterional approach. You can see the opticocarotid triangle, ipsilateral ICA, A1 as well as the chiasm and contralateral optic nerve in the distance. The black line indicates a lesioning of the optic nerve just proximal to the optic chiasm. This is the theoretical site of “Willbrand’s knee,” but as we will see, the theoretical anatomical finding has not been borne out in actual clinical practice. Even if you don’t know about this controversy, you can work out the correct answer by a process of elimination. Complete vision loss in the left eye is the correct answer. When it comes down to it, this is just a lesion of the ipsilateral optic nerve and it will produce a complete vision loss on that side. Willbrand, an anatomist, described the herniation of some nasal retinal fibers across the chiasm into the contralateral nerve in specimens that had lost the contralateral eye many years before. But, it hasn’t been shown in normal patients. Furthermore, the fibers originate from the inferior portion of the nerve and were said to produce a superior temporal field cut (which, conveniently, none of the answers suggests to you). Complete vision loss in the left eye with partial nasal field loss in the right eye is not the correct answer. A sectioning of the optic nerve just proximal to the chiasm that caught the fibers of the theoretical Willbrand’s knee, as discussed above, would result in a superior contralateral temporal, not a nasal, field cut (junctional scotoma). Bitemporal hemianopsia is not the correct answer. Lesions of the optic chiasm would cause a bitemporal field loss. Right homonymous hemianopsia is not the correct answer. This would result from a lesion of the left optic radiation or a lesion further along the visual pathway. Complete vision loss in the left eye with inferior temporal field loss in the right eye is not the correct answer. A sectioning of the optic nerve just proximal to the chiasm that caught the fibers of the theoretical Willbrand’s knee, as discussed above, would result in a superior contralateral temporal field cut (junctional scotoma).
An attempted fenestration of the third ventricular floor at the location indicated by the arrow in the figure shown has a high risk of resulting in which of the following complications?
Answers:
A. Diabetes insipidus
B. Injury to basilar artery
C. Uncontrollable bleeding
D. CN III palsy
E. Short term memory impairment
Diabetes insipidus
The correct answer is diabetes insipidus. The area indicated by the arrow is the infundibular recess, visualized in the midline as a red dimple in the ependyma; it gives rise to the pituitary stalk inferiorly. The hypothalamus is also at risk with perforation in this area as it, along with the infundibulum, contributes to the third ventricular floor. Injury to the infundibulum or the hypothalamic supraoptic and paraventricular nuclei can lead to diabetes insipidus. Generally, the diabetes insipidus is self-limited or requires only a short course of treatment; however, several cases of long-term or permanent diabetes insipidus have been reported. To prevent this complication, the ventriculostomy should be performed under direct visual control just anterior to the mamillary bodies and posterior to the infundibular recess. Injury to the basilar artery can occur at the normal ventriculostomy location as the basilar artery runs below the tuber cinereum. Once the ventriculostomy has been performed, the basilar artery should be visible, confirming entry into the prepontine cistern. Uncontrollable bleeding can come from the basilar artery, the intraventricular structures, the choroid plexius, or any number of veins encountered during the procedure. Short term memory impairment can come from contusion of the fornix or mamillary bodies. CN III palsy can come from damage to CN III or its nucleus.
A 45-year-old woman is evaluated because of a one-month history of intermittent headache and
nausea. The mass depicted in the photograph shown is the typical gross appearance of which of
the following lesions?
Answers:
A. Schwannoma
B. Epidermoid cyst
C. Dermoid cyst
D. Meningioma
E. Arachnoid cyst
Epidermoid cyst
The correct answer is an epidermoid cyst. The capsule of an epidermoid cyst is made of a thin layer of squamous epithelium which is shiny or “pearly” and white with an outer connective tissue wall. The pearly white capsule can be appreciated in this image. The cyst is often filled with keratin and solid cholesterol crystals. Dermoid cysts have a thicker rim than epidermoid cysts and include other elements such as lipid material from sebaceous glands. The wall of an arachnoid cyst can include ciliated cells, arachnoid tissue, or fibrous connective tissue and contains CSF. A Schwannoma would be arising from a parent nerve, and a meningioma would be extradural.
After undergoing embolization of the lesion shown, the patient emerges from anesthesia with altered mental status, vertical gaze palsy, and memory impairment. Which of the following vessels (A-E) is the most likely source for the deficits listed?
Answers:
A. A
B. B
C. C
D. D
E. E
B
B depicts the artery of percheron. Artery of percheron infarctions present with the triad of altered mental status, memory impariment, and vertical gaze palsy. A is the mid-basilar trunk and occlusion here would be expected to cause a “locked-in” syndrome with quadriparesis, respiratory muscle paralysis, preserved consciousness, and preserved ocular movements. C is an enlarged medial posterior choroidal artery in the setting of a shunting lesion. It arises from the P2 segment of the PCA and ascends deep to the rest of the PCA and supplies small branches to the tegmentum, midbrain, posterior thalamus and pineal gland along its cisternal segment. D is the P3 quadrigeminal segment of the right posterior cerebral artery. Occlusion here would be expected to cause contralateral homonymous hemianopia due to occipital infarction. E is the V3 segment of the right vertebral artery. Occlusion here would be expected to cause alteration of blood flow to the posterior cerebral circulation with possible resulting ischemia or infarction to the brainstem, cerebellum, and occipital lobes.
A 43-year-old man is evaluated because of acute-onset myelopathy consisting of gait disturbance,
weakness, and pain. The findings on the angiogram shown are associated with which of the
following?
Answers:
A. anterior choroidal aneurysm
B. moya moya disease
C. Foix-Alajouanine syndrome
D. vertebrobasilar stenosis
E. PICA aneurysm
Foix-Alajouanine syndrome
Foix-Alajouanine syndrome is a rare cause of myelopathy and is thought to be due to spinal venous congestion arising from an intradural shunting lesion such as an arteriovenous fistula or arteriovenous malformation. It typically affects the lower thoracic and lumbosacral levels. Arteriovenous fistula (AVF) leads to increased venous pressure, decreasing the arteriovenous pressure gradient and leading to a decrease in spinal cord perfusion, edema and necrosis. Early recognition and surgical intervention can result in a good prognosis. can present with longitudinally extensive transverse myelitis, progressive gait instability, and lower extremity weakness.Failure to promptly recognize this condition and misdiagnosis can result in a poor outcome. Microsurgical obliteration of the fistula may provide better long term results than embolization. PICA aneurysm, anterior choroidal aneurysm, vertebrobasilar stenosis and moya moya are not depicted.
