neurosurgery 1

Question 1

QUESTIONS 2-6
Scenario: A 54-year-old female was taken to an emergency
room after collapsing at work. She was alert and communicative,
with a severe headache, photophobia, nuchal rigidity,
and blurry vision. Computed tomography (CT) of the brain
revealed diffuse subarachnoid blood in the basal cisterns,
mild hydrocephalus, and no intraparenchymal hematoma.
Her angiogram is depicted below

Question 2

What is the clinical Hunt and Hess grade of this patient?
A. Grade I
B. Grade II
C. Grade III
D. Grade IV
E. Grade V

Answer 2

B. Grade II

Question 3

Some posterior communicating artery (PGomA) aneurysms
do not produce any third nerve deficit. Why should special
attention be given to the angiogram in these cases?

A. If the aneurysm is projecting posterolaterally rather
than in a more common medial position, there is an
increased risk of injuring the perforating vessels from
the PComA during microdissection

B. An aneurysm projecting laterally onto the medial edge
of the temporal lobe argues against premature retraction
of the temporal lobe

C. The angiogram may reveal a ventral carotid wall
aneurysm instead of a PGomA lesion, which is often
better managed with coiling

D. To look for any other associated aneurysms and/or
vasospasm

E. It may help with surgical planning, as medially projecting
lesions are better approached through the carotidoculomotor
triangle

Answer 3

B. An aneurysm projecting laterally onto the medial edge

Question 4

The patient is taken to the operating room for aneurysm
clipping. Proximal and distal control of the internal carotid
artery is obtained with temporary clip placement prior to
aneurysmal neck dissection. Despite this maneuver, the
aneurysm ruptures during microdissection and significant
bleeding is encountered, which significantly hinders visualization.
What preventative maneuver could have been
employed prior to aneurysmal rupture to decrease the
amount of intraoperative bleeding?

A. Blunt surgical microdissection
B. Obtaining proximal control of the internal carotid
artery in the neck
C. Releasing the dome of the aneurysm from the temporal
lobe prior to temporary clip placement to prevent traction
on the fundus
D. Identifying the distal posterior communicating artery
medial to the internal carotid artery for temporary clip
placement if possible
E. Temporary clip placement on the ophthalmic artery to
prevent retrograde bleeding from the orbit

Answer 4

D. Identifying the distal posterior communicating artery
medial to the internal carotid artery for temporary clip
placement if possible

Question 5

Postoperatively, the patient wakes up with contralateral
weakness, numbness, and homonymous hemianopia. A GT
scan of the brain shows an infarct in the posterior limb of the
internal capsule and in the adjacent white matter (above the
temporal horn of the lateral ventricle). This complication
might possibly have been avoided by

A. Identifying the anterior choroidal artery prior to
aneurysm clipping in order to prevent damage or
incorporation of this vessel into the clip construct

B. Increasing temporary occlusion time to prevent hasty
microdissection

C. Limiting the sylvian fissure dissection to the sphenoidal
portion in order to prevent unnecessary
dissection adjacent to PComA artery perforators,
which supply the posterior limb of the internal capsule

D. Obtaining an intraoperative angiogram to confirm
proper clip placement

E. Identifying and preserving the recurrent artery of
Heubner

Answer 5

A. Identifying the anterior choroidal artery prior to
aneurysm clipping in order to prevent damage or
incorporation of this vessel into the clip construct

Question 6

Postoperatively, the patient sustained damage to the
frontal branch of the facial nerve. What is the most likely
reason for the frontal branch facial nerve injury?

A. The supraorbital nerve was not identified in detaching
the scalp from the supraorbital rim
B. The incision was started less than 1 cm anterior to the
tragus
C. There was nerve neuropraxia from postoperative
swelling
D. The nerve in the subgaleal fat pad was injured during
surgical dissection
E. The nerve between the superficial and deep layers of
the temporalis fascia was injured with monopolar
cautery

Answer 6

D. The nerve in the subgaleal fat pad was injured during

posterior communicating artery (PGomA) aneurysms typically present with subarachnoid hemorrhage (SAH) and partial or complete third nerve palsies (ptosis, dilated pupil,extraocular muscle abnormalities) due to compression of the
third nerve by the aneurysm. Another common presentation of PGomA aneurysms is the development of a third nerve deficit in the absence of SAH. The appearance of an enlarged
pupil with or without involvement of other third nerve functions should be taken as diagnostic of a PGomA aneurysm until proven otherwise. After the aneurysm is clipped, it should be punctured not only to ensure complete obliteration but also to achieve maximal decompression of the third nerve. Most patients with third nerve palsies improve within 6 months and frequently sooner. Some PGomA aneurysms
will not produce any oculomotor nerve deficit. Special care must be taken in interpreting the angiograms of these patients, since the aneurysms often project laterally onto the medial edge of the temporal lobe rather than in more common
posterolateral or downward directions. This is relevant during operative planning, since early retraction of the temporal lobe may result in premature aneurysmal rupture

Question 7

QUESTIONS 8 - 11
Scenario: A 28-year-old male was involved in a motorcycle
accident. About 1 week after being discharged from the
hospital he began experiencing fevers, severe retroorbital
headaches, diplopia, and left eye proptosis, which prompted
a visit to the emergency department. A computed tomography
(GT) scan of the brain showed a resolving 2- by 3-cm left
frontal contusion underlying a minimally displaced frontal
bone fracture, which was sustained at the time of initial
injury. His erythrocyte sedimentation rate (ESR) and Greactive
protein (GRP) were mildly elevated. The angiogram
is depicted below

Question 8

What is the most likely diagnosis?

A. Superior orbital fissure syndrome
B. Incidental meningioma originating from the medial
aspect of the sphenoid ridge
C. Arterial-venous fistula
D. Occlusion of the internal carotid artery proximal to the
ophthalmic artery origin
E. Cavernous sinus thrombosis

Answer 8

C. Arterial-venous fistula

Question 9

The signs/symptoms of this disease process depend
mostly upon

A. The size and location of the tumor relative to the optic
nerve
B. The direction of venous drainage and rate of blood flow
through the shunt
C. The extent of the inflammatory reaction adjacent to
the cavernous sinus
D. The extent of the inflammatory reaction adjacent to
the superior orbital fissure
E. The extent of collateral flow from the opposite internal
carotid artery and external meningeal feeders

Answer 9

B. The direction of venous drainage and rate of blood flow
through the shunt

Question 10

What should be the initial treatment of choice for this
patient?

A. Six weeks of antibiotics followed by repeat angiography
B. Glue embolization of major arterial feeders followed by
tumor resection
C. Carotid artery sacrifice
D. Transarterial detachable balloon embolization
E. Heparin infusion

Answer 10

D. Transarterial detachable balloon embolization

Question 11

If the desired treatment strategy fails, what would be
another potential treatment option?
1. Surgical debridement of the infection
2. Direct surgical packing of the cavernous sinus with
either Gelfoam, Surgicel, platinum coils, or strands of
cotton
3. Preoperative glue embolization of arterial feeders
followed by tumor resection
4. Endovascular procedure for internal carotid artery
sacrifice

A. 1, 2, and 3 are correct
B. 1 and 3 are correct
C. 2 and 4 are correct
D. Only 4 is correct
E. All of the above
End of set

Answer 11

C. 2 and 4 are correct

Carotid-cavernous fistulas (CCFs) can be
divided into posttraumatic and spontaneous types. They are
direct shunts between the ICA or ECA and cavernous sinus
and usually occur after trauma or spontaneous aneurysmal
rupture. Traumatic CCFs often present in a delayed fashion;
like spontaneous fistulas, they often present with retro-orbital pain, chemosis, pulsatile proptosis, ocular or cranial bruit,
decreased visual acuity, diplopia, and rarely epistaxis and
subarachnoid hemorrhage. The symptoms depend on the
direction of venous flow and quantity of blood flow through
the fistula. There are four types of GGFs: type A is a direct,
high-flow shunt between the IGA and cavernous sinus (as in this case), and types B to D are low-flow shunts between
the cavernous sinus and meningeal branches of the internal carotid artery, external carotid artery, or both, respectively. Approximately 50% of low-flow fistulas spontaneously
thrombose without treatment. The main treatment option has traditionally included transarterial balloon embolization through the IGA for type A fistulas, although accessing the fistula transvenously (i.e., inferior petrosal sinus) is also commonly performed, especially for indirect types B to D.
A direct surgical approach is indicated if transarterial or transvenous approaches fail. Radiosurgery has been proposed as an option for some of the low-flow fistulas, although it would not be the best strategy for the high-flow symptomatic fistula seen in this patient. Figure A depicts nearly
complete capture of the blood from the internal carotid
artery, and fistulous drainage primarily from the superior ophthalmic and superior petrosal veins. Figure B depicts a later venous run with superior petrosal vein drainage into the transverse-sigmoid sinus junction as well as some venous drainage into the superior sagittal sinus (Kaye and Black,

Question 12

What finding in the pathologic process depicted by
the angiogram below (Figure 6.10Q.) would mandate urgent treatment?

A. Retrograde cortical venous drainage
B. Multiple meningeal artery feeders
C. Dual internal and external carotid artery supply
D. Embolic stroke
E. Venous sinus occlusion

Answer 12

A. Retrograde cortical venous drainage

The natural history of DAVF is variable and includes spontaneous resolution, recruitment of meningeal arterial feeders, and the development of intracranial hypertension.
DAVF can present with pulsatile tinnitus, visual symptoms, papilledema, hydrocephalus, and intracranial hemorrhage.
The presence of retrograde cortical venous drainage indicates the potential for intracranial hemorrhage and mandates urgent treatment of the DAVF. Intracranial hemorrhage from a DAVF in the absence of retrograde cortical venous drainage has not been reported. Hemorrhage from a DAVF is associated with a high morbidity and mortality (approximately 30%). Ectatic dilation or venous occlusion of the involved sinus, multiple or dual ICA/ECA arterial feeders, or embolic stroke, in the absence of retrograde cortical venous drainage has not been reported to increase hemorrhage rates of DAVFs

Question 13

QUESTIONS 14-17
Scenario: A 67-year-old male with a history of diabetes
mellitus and hypertension presents to the emergency department
with right arm weakness and numbness. He is found to
have > 90% stenosis of the left internal carotid artery and
restricted MR diffusion in portions of the brain supplied by
the left middle cerebral artery. He elects to proceed with
surgery for his carotid stenosis but is found to have a highriding
carotid artery bifurcation.

Question 14

Surgical maneuvers that may increase surgical exposure
of a high-riding carotid artery bifurcation during carotid
endarterectomy include all of the following EXCEPT?

A. Medial mobilization of the ansa cervicalis
B. Dividing the posterior belly of the digastric muscle
C. Mandibular osteotomy or disarticulation of the mandible
at the temporomandibular joint
D. Judicious cautery and ligation of select vessels (occipital
artery, common facial vein) hindering exposure
E. Transverse sectioning of the clavicular head of the
sternocleidomastoid muscle at the level of the hyoid
bone for better visualization of the carotid artery
lateral to the jugular vein

Answer 14

11-E

Question 15

What cranial nerve is at most risk of injury when exposing
a high-riding carotid artery bifurcation?
A. VII
B. IX
C. X
D. XI
E. XII

Answer 15

; 12-E

Question 16

What is the order of clamp placement on the arteries
during carotid endarterectomy?
A. External, internal, common
B. Internal, common, external
C. External, common, internal
D. Common, external, internal
E. Common, internal, external

Answer 16

B. Internal, common, external

Question 17

After clamp placement and arteriotomy, the surgeon
notices continued bleeding from the back wall of the carotid
artery, which severely hinders visualization during the
surgical procedure. What is the most likely reason for the
continued bleeding?
A. Incomplete clamping of the common carotid artery
B. Backbleeding from the superficial temporal artery
C. Backbleeding from the ascending pharyngeal artery
D. Venous bleeding from the adventitia of the internal
carotid artery
E. Clotting abnormality from heparin infusi

Answer 17

C. Backbleeding from the ascending pharyngeal artery

Question 18

During surgical dissection adjacent to the carotid
artery, the anesthesiologist notices that the patient becomes hypotensive and bradycardic. The next course of management should include

A. Obtain an immediate arterial blood gas (ABG) to
determine if the patient is suffering from a pulmonary
embolus
B. Check cardiac enzymes, as the patient is likely suffering
from an anterior myocardial wall infarction
C. The nerve to the carotid sinus (nerve of Hering) should
be anesthetized with 0.5 mL of 2% lidocaine
D. Begin dobutamine, check central venous pressures,
and obtain a lactate level, as the patient is likely to be
volume-depleted
E. 100 IU/kg of heparin should be infused intravenously
to prevent further emboli

Answer 18

C. The nerve to the carotid sinus (nerve of Hering) should
be anesthetized with 0.5 mL of 2% lidocaine

Question 19

Postoperatively, the patient awoke with right-sided
hemiplegia and lethargy. The next logical course of management should include

A. Immediate CT angiography to assess the patency of the
right carotid artery
B. Immediate selective angiography of the right carotid
artery
C. Antiplatelet therapy for 1 week, followed by repeat
angiography
D. Stent placement across the arteriotomy site to reinforce
the closure
E. Immediate surgical reexploration for thrombectomy

Answer 19

Attempts to gain additional exposure for a high-riding carotid artery bifurcation include mobilization of the ansa cervicalis, sectioning the posterior belly of the digastric muscle, cautery and ligation of the occipital artery, and mandibular osteotomy or disarticulation of the jaw at the temporomandibular joint. This type
of exposure places the hypoglossal nerve at particular risk, although segments of cranial nerves VII, IX, X, and XI can also be injured during carotid endarterectomy (GEA).
Patients who become hypotensive and bradycardic during surgery often do so as a result of manipulation of the nerve of Hering near the carotid bulb. This is not uncommon with GEA and can often be addressed with lidocaine infusion adjacent to the carotid bulb. Placing the clamps on the internal
carotid artery first, followed by the common and then the external carotid artery often ensures that the clot will pass through the external carotid artery instead of the internal carotid artery. The order for clamp removal should be just the opposite, as this should again ensure that any accumulated blood clot will be more likely to pass through the
external rather than internal carotid circulation. It is not
uncommon during GEA to have some backbleeding into the surgical field by the ascending pharyngeal artery after clamp placement on the major vessels. If the extent of bleeding is severe and hinders the operation, identification, clamping (aneurysm clip), or ligation of this vessel may drastically improve visibility. A patient who awakens with a major
neurologic deficit is likely to have suffered thrombosis at the arteriotomy site, which usually warrants immediate attention (surgical exploration) rather than time-consuming diagnostic studies, as some case reports describe a significant neurologic improvement if flow is re-established within 45 minutes. For later-onset deficits, workup (i.e., CT, angiogram) may be indicated. GT may help to identify hemorrhage and an angiogram may reveal whether the IGA is occluded or if the deficit is from another cause (emboli) that would not necessarily require surgical re-exploration

Question 20

QUESTIONS 21-22
A 15-year-old female undergoes uncomplicated resection of the lesion depicted below (Figure 6.17-6.18Q). Four days later she develops lethargy, fever, meningismus, and photophobia.
A cerebrospinal fluid (CSF) sample reveals a protein
level of 86 mg/dL (reference range, 12 to 60 mg/dL), a glucose level of 61 mg/dL (reference range, 40 to 70 mg/dL), 16 red blood cells/mL, and 126 white blood cells/mL with a differential of 11% neutrophils, 82% lymphocytes, and 7% histiocytes. Gram stain and culture of CSF were sterile and remained so for the presence of organisms.

Question 21

What is the most likely diagnosis?
A. Bacterial meningitis
B. Aseptic meningitis
C. Hydrocephalus
D. Postmeningitis syndrome
E. Viral encephalitis

Question 22

What is the natural history of this problem?
A. Requires a 10-day course of antibiotics despite negative
cultures to cover for slow-growing bacterial species
B. Patients frequently require steroid therapy followed
by repeat lumbar punctures
C. Usually self-limited and requires no treatment
D. Patients show drastic improvement with shunting
E. Usually favorable once any synthetic material placed
during surgery (e.g., dural graft) is removed

Answer 22

C. Usually self-limited and requires no treatment

Aseptic meningitis (AM) is a well-recognized
complication after posterior fossa surgery but is typically
self-limited and requires no treatment. It has generally been attributed to one or more irritants released into the subarachnoid space during surgery, including blood breakdown
products, tumor, muscle, and brain. Lowering of intracranial pressure with lumbar puncture and dexamethasone is the mainstay of treatment in certain patients with continued, problems. Bacterial meningitis and postmeningitic syndrome are unlikely, considering that an organism was not isolated from the CSF, although this is not always the case. Moreover, the CSF profile was more consistent with aseptic meningitis than bacterial meningitis. Hydrocephalus is unlikely, since fever, meningismus, and photophobia rarely accompany this diagnosis, and encephalitis would be very uncommon in this situation

Question 23

A 62-year-old female undergoes microvascular decompression for hemifacial spasm. Postoperatively, she has complete
ipsilateral deafness but no other neurologic deficits.
The most likely cause of this deficit was injury to one of the blood vessels that originated from which artery?

A. Posterior cerebral artery (PCA)
B. Superior cerebellar artery (SCA)
C. Anterior inferior cerebellar artery (AICA)
D. Posterior inferior cerebellar artery (PICA)
E. Vertebral artery

Answer 23

C. Anterior inferior cerebellar artery (AICA)

Complications of microvascular decompression for
hemifacial spasm include CSF leak, facial weakness, facial
anesthesia, corneal anesthesia, intracranial hemorrhage,
and infarction. Complete ipsilateral deafness is associated with disruption or coagulation of the labyrinthine artery,
which is most commonly a branch of either the AICA
(45%), SGA (25%), or basilar artery (16%)

Question 24

A 14-year-old girl with progressive loss of vision in her
right eye was recently diagnosed with a 2.0- by 3.5-cm right
optic nerve glioma extending to the optic chiasm. During
surgery, the portion of the tumor on the optic nerve was
successfully resected, but the tumor adjacent to the optic
chiasm was left behind. What is the maximal dose of singlefraction
radiosurgery that can safely be employed to the
optic chiasm?
A. 4 to 7 Gy
B. 9 t o l O G y
C. 11 to 13 Gy
D. 14 to 16 Gy
E. 21 Gy

Answer 24

B. 9 t o l O G y

The maximal safe dose of single-shot radiosurgery
that the optic chiasm can tolerate is approximately 9 to
10 Gy

Question 25

A surgeon decides to utilize an infratentorialsupracerebellar corridor to approach a pineal region mass. What blood vessel is frequently cauterized and divided for better exposure of the posterior surface of the tumor during this approach? A. Vein of Galen B. Ipsilateral basal vein of Rosenthal C. Posterior cerebral artery (PGA) D. Precentral cerebellar vein E. Superior petrosal sinus

Answer 25

D. Precentral cerebellar vein Cauterizing and dividing the precentral cerebellar vein will often expose the posterior surface of pineal region tumors. The veins of Galen and Rosenthal should be preserved during this operation, as well as the vermian vein, which often can be spared in this approach. The choroidal arteries may supply feeders to the tumor but rarely need to be cauterized and ligated for adequate tumor resection

Question 26

During translabyrinthine exposure for acoustic neuroma resection, surgeons find themselves exposing Trautmann's triangle. All of the following structures delineate this area EXCEPT? A. A triangular patch of dura on the posterior aspect of the temporal bone facing the cerebellopontine angle B. The sigmoid sinus laterally C. The superior petrosal sinus above D. The jugular bulb below E. The foramen magnum medially

Answer 26

E. The foramen magnum medially There are two goals of the translabyrinthine approach for acoustic neuroma resection that may help achieve maximal tumor resection. The first is to remove enough bone to identify the nerves lateral to the tumor as they course through the IAG, and the second is to expose the dura of the posterior aspect of the temporal bone that faces the cerebellopontine angle (CPA). This triangular patch of dura facing the CPA is called Trautmann's triangle and extends from the sigmoid sinus laterally, the superior petrosal sinus above, and the jugular bulb below. The foramen magnum is not included in Trautmann's triangle

Question 27

One of the earliest procedures performed for Parkinson's disease was ligation of what blood vessel? A. Anterior choroidal artery B. Medial posterior choroidal artery C. Recurrent artery of Heubner D. Tentorial artery of Bernasconi and Cassarini E. Medial lenticulostriate artery

Answer 27

A. Anterior choroidal artery Neurosurgical therapies for Parkinson's disease (PD) have been utilized in patients with progressive disease despite maximal medical therapy. An early procedure performed for PD was ligation of the anterior choroidal artery, with subsequent infarction of the pallidum. Due to the variable distribution of this vessel outside the confines of the pallidum, results were too unpredictable and this procedure lost favor. In the 1950s, anterodorsal pallidotomy became an accepted procedure, but the long-term benefits were mostly for rigidity, while tremor and dyskinesia did not improve. Subsequently, the ventrolateral thalamus became the preferred target for lesioning, but this procedure also lost favor, as patients were often still left with bradykinesia and/or rigidity. Moreover, this procedure reduced tremor only in the contralateral half of the body, and bilateral thalamotomies were not recommended due to an unacceptably high risk of postoperative dysarthria and gait disturbances. Thalamotomy procedures fell off dramatically in the late 1960s with the introduction of L-DOPA. More recently, dramatic and beneficial effects of both subthalamic nucleus (STN) and globus pallidus interna (Gpi) deep brain stimulation (DBS) have been consistently observed. Both interventions appear to result in significant improvements in both motor fluctuations and dyskinesias. The DBS study group, in a large multicenter study, reported that on time without dyskinesia during the waking hours increased from 25 to 30% at baseline to 65 to 75% 6 months postoperatively. In a complementary fashion, these procedures also markedly decreased off time and on time without dyskinesia. Although some preliminary studies suggest STN DBS may be a superior intervention, no large randomized controlled trial comparing STN and Gpi DBS has been conducted to compare the efficacy of these treatments. The most consistent finding has been the reduction in antiparkinson medication following STN DBS compared to Gpi DBS.

Question 28

Vagal nerve stimulation is reserved for select patients with epilepsy. Why is it performed on the left side? A. To avoid injuring the recurrent laryngeal nerve, which follows a more torturous route on the right B. To avoid damage to the dominant superior laryngeal nerve on the right C. To avoid damage to cranial nerve X, which supplies the heart mainly from the right D. To avoid injuring the thoracic duct E. Less chance of vocal cord paralysis and hoarseness from the left

Answer 28

C. To avoid damage to cranial nerve X, which supplies the heart mainly from the right Vagal nerve stimulation must be performed on the left side so that the cardiac innervation of GN X is unaffected

Question 29

What basal cistern(s) contain portions of the vein of Rosenthal? 1. Crural 2. Quadrigeminal 3. Ambient 4. Quadrigeminal A. 1, 2, and 3 are correct B. 1 and 3 are correct C. 2 and 4 are correct D. Only 4 is correct E. All of the above

Answer 29

B. 1 and 3 are correct Dorsal root entry zone (DREZ) lesioning involves radiofrequency ablation along the dorsolateral sulcus of the spinal cord. The DREZ procedure is most effective in the treatment of brachial and lumbar plexus avulsion pain. Direct sectioning of the spinothalamic tract (cordotomy) is very effective for unilateral pain below the upper chest region; however, it is associated with many complications and is usually performed only in terminally ill patients. Complications of cordotomy include hemiparesis, respiratory depression ("Ondine's curse" with bilateral procedures), and dysesthesias. Midline myelotomies can also be performed to interrupt the decussating fibers of the spinothalamic tract, and this can be quite effective in the treatment of chronic pelvic pain secondary to cancer. Intrathecal narcotic administration is typically used for the treatment of chronic pain associated with malignancy or failed low back syndrome. Deep brain stimulation of the VPL and VPM nuclei of the thalamus as well as the periaqueductal gray have been performed in the treatment of thalamic pain states, postherpetic neuralgia, and causalgia. Chronic low-threshold stimulation of the motor cortex is also utilized in the treatment of thalamic pain syndromes; it is thought to work by retrograde thalamic stimulation pathways

Question 30

A 3-month-old boy is brought to your office for an abnormally shaped head. The child is noted to have a flat occiput on the left, a left ear that is anterior to the right, and a prominent forehead and malar eminence on the left. What is the most likely etiology of this deformity? A. Left lambdoid synostosis B. Right lambdoid synostosis C. Sagittal suture synostosis D. Skull molding E. Right coronal suture synostosis

Answer 30

D. Skull molding

Question 31

All of the following are suboptimal conditions for placement of an odontoid screw EXCEPT? A. Old fractures (\> 6 weeks) B. Diagonal fractures through the odontoid process C. Barrel-chested patient D. Odontoid fracture that is displaced anteriorly E. An intact transverse ligament

Answer 31

D. Odontoid fracture that is displaced anteriorly Lambdoid synostosis is among the rarest forms of suture synostosis, while sagittal synostosis is the most common. After the American Academy of Pediatrics published its recommendations that all children sleep on their back, the incidence of skull molding increased. Most infants sleep on 202 Intensive Neurosurgery Board Review their backs and spend the rest of the day sitting in a car seat or infant seat. Children with this condition are often noted to have a flat occiput, one ear that is anterior to the other in an axial plane, and a prominent forehead and malar eminence. Many infants may also have a mild torticollis due to a shortened sternocleidomastoid muscle on one side, as well as decreased range of motion in the neck. The skull deformity usually responds very well to behavioral modification, which includes having the parents turn the infant or child from side to side during sleep and reducing the amount of time spent in a car seat. If this is unsuccessful, a molding helmet or band is often helpful. For nonresponders, a variety of occipital remolding surgical procedures are available

Question 32

A 56-year-old female underwent clipping of the aneurysm depicted on the angiogram below Upon awakening from surgery, she was noted to have greater weakness in her left arm than in her left leg. What is the most likely reason for this new deficit? A. Injury of a blood vessel originating from the A2 segment of the anterior cerebral artery B. Venous infarct from excessive frontal lobe retraction C. Injury to the small perforating blood vessels originating from the anterior communicating artery D. Posterior internal capsule infarction from microemboli originating from the internal carotid artery E. Mesial temporal lobe retraction

Answer 32

A. Injury of a blood vessel originating from the A2 segment of the anterior cerebral artery The recurrent artery of Heubner usually originates from the A2 segment of the anterior cerebral artery (ACA). Injury of this vessel during surgery is generally witnessed on the first postoperative day, as evidenced by a hypodensity on CT scan. Although injury to this vessel during surgery often presents with arm weakness greater than leg weakness on the nondominant side and cognitive deficits from injury on the dominant side, a percentage of patients do not have any adverse neurologic sequelae after injury of this vessel. Identifying this vessel early in the dissection may prevent later injury

Question 33

Basilar skull fractures can be associated with cranial nerve palsies, bilateral periorbital ecchymosis, mastoid ecchymosis, hemotympanum, and rhinorrhea. Nasal drainage that is not clearly CSF can be assayed for , which is unique to CSF and . A. a-Fetoprotein, saliva B. p\-Transferrin, vitreous fluid of the eye C. (^-Transferrin, tears D. Hypoglycorrhachia, nasal secretions E. Sodium, peritoneal fluid

Answer 33

B. p\-Transferrin, vitreous fluid of the eye pVtransferrin is present in the CSF but absent in the tears, saliva, peritoneal fluid, nasal exudates, and serum (except for newborns or those with liver disease). The only other source is the vitreous humor of the eye. Other commonly employed tests include measuring the glucose level of the fluid (CSF glucose \> 30 mg %, whereas lacrimal and mucous secretions are \< 5 mg%) or placing the fluid on a piece of linen (bed sheet, pillowcase) and seeing whether a ring of blood surrounded by a larger concentric ring of clear fluid develops ("ring"' or "halo" sign)

Question 34

A 4-month-old male fell from his crib and suffered a growing skull fracture. All of the following are true of this disease entity EXCEPT? A. May be associated with late neurologic deficits B. A dural laceration is always present C. There may be ongoing damage to underlying brain from continued herniation of brain through the defect D. CSF diversion is often the only treatment required for this fracture pattern E. May be associated with leptomeningeal cyst development

Answer 34

D. CSF diversion is often the only treatment required for this fracture pattern Growing skull fractures occur in children, are always associated with underlying dural lacerations, and almost always require surgical treatment. Early surgical correction of growing fractures is often necessary because these types of fractures almost never heal spontaneously and late neurologic deterioration can occur. The pathophysiology requires a fracture with enough force to cause a tear in the dura (which is always present) and an underlying constant force such as a growing brain, leptomeningeal cyst, hydrocephalus, or porencephaly. The precise etiology of late neurologic deficits remains unclear but is believed to occur by one of two mechanisms. There may be ongoing brain damage from brain herniation and pulsations of the brain against the bone edges. Alternatively, some have proposed that there may be vascular compromise of blood vessels at the bone edges. Although some authors have recommended a CSF diversion procedure for growing skull fractures, direct repair of the fracture is the definitive treatment

Question 35

A 54-year-old female completed radiation therapy for breast cancer. She has been complaining of weakness in her left arm over the past 3 months and is concerned there may be recurrence of her cancer. How can her physician distinguish between radiation-induced plexopathy and cancerous invasion of the brachial plexus? A. Radiation-induced plexopathy is frequently accompanied by pain and lack of edema B. Cancerous invasion of the brachial plexus is accompanied by lymphedema, painless weakness, and sensory loss C. Radiation-induced plexopathy is frequently reversible D. Myokymia on EMG favors radiation-induced plexopathy E. Prolonged H latency is typically seen only with brachial plexopathy secondary to radiation damage

Answer 35

D. Myokymia on EMG favors radiation-induced plexopathy Myokymia (quivering of muscles) on EMG strongly favors radiation-induced changes of the brachial plexus. Lymphedema, painless paresis, and numbness suggest radiation-induced injury (irreversible), whereas pain and lack of edema suggest recurrent tumor. When ancillary studies are inconclusive, surgical exploration of the plexus may have to be considered

Question 36

QUESTIONS 36-39 Scenario: A 42-year-old male falls 25 feet while at work and arrives at the emergency department with a Glasgow Coma Scale (GGS) score of 5, a dilated and nonreactive right pupil, and a mean arterial blood pressure of 80. After airway management and fluid resuscitation, his GGS improves to 7, but his right hemiparesis and nonreactive pupil remain unchanged. The patient also sustained a pelvic fracture, a left humeral fracture, splenic and liver lacerations, and multiple fractures of the cervical spine. Initial management of this patient should include 1. Begin hyperventilation to decrease the pG02 2. Administer mannitol on arrival to the emergency department because of clinical evidence of an asymmetric exam 3. Complete the primary survey, obtain cervical spine films and chest x-ray, and then move directly to CT scan 4. The patient should be started on pentobarbital for elevated intracranial pressure immediately after completion of the primary survey if no mass lesion is found on CT A. 1, 2, and 3 are correct B. 1 and 3 are correct C. 2 and 4 are correct D. Only 4 is correct E. All of the above

Answer 36

B. 1 and 3 are correct

Question 37

The CT scan of the brain is depicted below Why did this patient develop hemiparesis on the same side as the hematoma? A. Shift of the brainstem away from the mass producing compression of the contralateral cerebral peduncle against the tentorium B. The patient likely suffered a Duret hemorrhage C. There was likely a contusion in the underlying motor cortex on the contralateral side that was not detected on the initial CT scan D. The patient likely had a left internal carotid artery dissection that subsequently showered emboli to the distal vasculature E. There was an associated fracture of the transverse foramen on the left, which produced a vertebral artery dissection and small infarct in the ventral pons

Answer 37

A. Shift of the brainstem away from the mass producing

Question 38

Which of the following are possible complications of mannitol administration? 1. Aggravation of vasogenic edema 2. Development of a hyperosmolar nonketotic state 3. Acute tubular necrosis 4. Hypotension A. 1, 2, and 3 are correct B. 1 and 3 are correct C. 2 and 4 are correct D. Only 4 is correct E. All of the above

Answer 38

E. All of the above

Question 39

After surgery for evacuation of the right subdural hematoma, CT angiogram was obtained to rule out a vertebral artery injury because of the multiple fractures of the cervical spine extending through the transverse foramina. The study was inconclusive, and a follow-up angiogram was obtained later that evening after hematoma evacuation. What would be the most reasonable treatment strategy at this point for this multisystem trauma patient? Consider that the patient adequately fills the posterior circulation from the right vertebral artery. 1. Commencement of a heparin infusion with a goal of keeping the PTT approximately two times the normal level 2. Antiplatelet therapy 3. Intravenous t-PA 4. Endovascular sacrifice of the occluded vertebral artery A. 1, 2, and 3 are correct B. 1 and 3 are correct C. 2 and 4 are correct D. Only 4 is correct E. All of the above

Answer 39

C. 2 and 4 are correct Current head injury research guidelines suggest that mannitol and hyperventilation may exacerbate cerebral ischemia after head injury. However, mannitol and hyperventilation are recommended for those patients with acute head injury as a temporary measure to control elevated intracranial pressure. Hyperventilation may be commenced immediately, but mannitol should be withheld until the primary survey is complete and adequate intravascular volume and urine output are realized. The mechanism of action of mannitol is still debated, but it is believed to have the following beneficial effects. First, it acts to immediately expand the plasma by reducing hematocrit and blood viscosity (improved rheology), which improves CBF and O-, delivery. This reduces ICP very quickly, which is most marked in patients with CPP \< 70 mm Hg. Second, it draws edema from the adjacent cerebral parenchyma into the intravascular compartment (osmotic effect), an effect that may last up to 6 hours. And last, it is a possible freeradical scavenger. Despite these short-lived but beneficial effects, the administration of mannitol is not without risks. It opens the blood-brain barrier and can potentially draw fluid into the CNS and aggravate vasogenic cerebral edema. It should also be used cautiously with concomitant administration of steroids and phenytoin (Dilantin), as it may cause a nonketotic hyperosmolar state, with high mortality. With overuse, it can also result in hypertension and increased CBF if cerebral autoregulation is defective. And last, high doses carry a significant risk for the development of acute renal failure, especially with coexisting sepsis, concomitant nephrotoxic drug use, serum osmolality \> 320, or preexisting kidney disease. Some patients with mass lesions on one side may not uniformly develop contralateral hemiparesis as expected. In some cases, brainstem shift away from the mass lesion (e.g., EDH, SDH) may produce compression of the opposite cerebral peduncle against the tentorium, which results in hemiparesis on the same side as the lesion (Kernohan's notch phenomenon), a false localizing sign. Injury to the vertebral artery (VA) after trauma can result in various abnormalities. The most severe is total occlusion of the vessel, which can result in infarction if there is not adequate collateral blood flow. One major risk (besides acute infarction) of traumatic vertebral artery occlusion is the potential for recanalization and embolization to downstream vessels. Although the precise incidence of recanalization and downstream embolization remains unknown, many favor sacrificing the artery via an endovascular approach to prevent this occurrence if collateral circulation is adequate. Moreover, this may potentially decrease the need for anticoagulation or antiplatelet therapy during the acute period in high-risk, multisystemtrauma patients. Others opt for less drastic strategies for dealing with this problem, such as observation or starting antiplatelet therapy, as compared to anticoagulation and t-PA, which may carry a higher hemorrhage risk in traumatized patients. Patients with spontaneous or traumatic partial occlusion, dissection, or pseudoaneurysm formation of the vertebral or carotid arteries may also pose a difficult treatment dilemma, especially if there is bleeding in other locations from trauma. Each institution usually has its own guidelines, based on the literature, for managing such patients. Nevertheless, optimal treatment has not yet been determined. For patients without serious bleeding in other locations, many authors advocate anticoagulation with IV heparin for 1 to 2 weeks followed by warfarin (Coumadin) for an additional 4 to 12 weeks, as most arterial injuries have been noted to heal with recanalization within 6 weeks. For patients at high risk for bleeding with anticoagulation, some advocate aspirin and/or clopidogrel bisulfate (Plavix) therapy as an alternative to anticoagulation, which may (potentially) be associated with less risk of bleeding. Further studies are warranted to determine the best strategy for these types of injuries

Question 40

QUESTIONS 40-42 Scenario: A 45-year-old male presents to an emergency room with fever, nausea, vomiting, and severe headache. CT of the brain is normal. Lumbar puncture reveals slightly elevated red blood cells, but normal protein, glucose, white blood cell count, and no xanthochromia. His angiogram is depicted below. What is the most likely etiology of the abnormality depicted in the angiogram below ? A. Head trauma B. Infection C. Genetic predisposition D. Collagen vascular disease E. Hypertension

Answer 40

B. Infection

Question 41

This finding occurs most frequently in what condition? A. Alcoholism B. Ehlers-Danlos disease C. Subacute bacterial endocarditis D. Marfan's syndrome E. Polycystic kidney disease

Answer 41

C. Subacute bacterial endocarditis

Question 42

Scenario: A 45-year-old male presents to an emergency room with fever, nausea, vomiting, and severe headache. CT of the brain is normal. Lumbar puncture reveals slightly elevated red blood cells, but normal protein, glucose, white blood cell count, and no xanthochromia. How should this problem be treated? A. Observation followed by repeat angiography in 6 months B. Antibiotics followed by repeat angiography C. Emergent surgery D. Stent/coiling followed by blood pressure control E. Steroids

Answer 42

B. Antibiotics followed by repeat angiography Mycotic or infective aneurysms account for about 4% of intracranial aneurysms and are most commonly found along the distribution of the distal middle cerebral artery (MCA). Patients with head trauma also are at risk of developing aneurysms, although these are most frequently located along the distal anterior cerebral artery distribution. Mycotic aneurysms occur in about 3 to 15% of patients with subacute bacterial endocarditis (SBE), and the most common organism isolated from the blood is Streptococcus viridans species. Patients that are IV drug abusers or immunodeficient (HIV) are at increased risk of developing this disease entity. Most cases are treated with 4 to 6 weeks of antibiotics followed by repeat angiography to document effectiveness of therapy. Delayed clipping may be feasible for patients with subarachnoid hemorrhage, an increase in the size of the aneurysm on antibiotics, or failure to reduce in size after completion of antibiotics