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ABNS Neurological Surgery study materials
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ABNS Neurological Surgery practice questions

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Question 1Neurotrauma and Critical Care

A 24-year-old man arrives after a motorcycle crash with a Glasgow Coma Scale score of 5. According to the Advanced Trauma Life Support and Brain Trauma Foundation principles, which parameter should be targeted for his systolic blood pressure during resuscitation?

  1. At least 90 mm Hg
  2. At least 140 mm Hg
  3. At least 100 mm Hg
  4. At least 110 mm Hg Correct answer.

Explanation

Current Brain Trauma Foundation guidance recommends maintaining systolic blood pressure at 110 mm Hg or greater for adults with severe traumatic brain injury to preserve cerebral perfusion pressure. Hypotension is a strong independent predictor of secondary injury and poor outcome.

Question 2Neurotrauma and Critical Care

Which finding on the Glasgow Coma Scale contributes the most to a low total score in an intubated patient with severe traumatic brain injury?

  1. Abnormal flexion to painful stimulus
  2. Inability to verbalize due to the endotracheal tube
  3. Confused speech
  4. Absent eye opening Correct answer.

Explanation

The GCS motor score is the strongest predictor of outcome, but eye opening is scored independently and absent eye opening reflects brainstem dysfunction. In intubated patients the verbal score is often recorded as 1T, which artificially lowers the total and should be interpreted cautiously.

Question 3Neurotrauma and Critical Care

A patient with a traumatic epidural hematoma classically presents with a lucid interval followed by rapid deterioration. Which artery is most commonly the source of bleeding?

  1. Middle meningeal artery Correct answer.
  2. Superior sagittal sinus
  3. Middle cerebral artery
  4. Bridging cortical veins

Explanation

Epidural hematomas most often result from fracture of the temporal bone with laceration of the middle meningeal artery. The arterial source explains the characteristic lucid interval and rapid expansion.

Question 4Neurotrauma and Critical Care

Which imaging feature best distinguishes an acute subdural hematoma from an epidural hematoma on non-contrast CT?

  1. Biconvex shape limited by sutures
  2. Hyperdensity that crosses suture lines Correct answer.
  3. Presence of a fluid level
  4. Association with a skull fracture

Explanation

Subdural hematomas spread freely under the dura and therefore cross suture lines and are crescent-shaped. Epidural hematomas are bounded by dural attachments at sutures and appear biconvex.

Question 5Neurotrauma and Critical Care

A 45-year-old with a severe traumatic brain injury has an intracranial pressure of 25 mm Hg and a mean arterial pressure of 70 mm Hg. What is the cerebral perfusion pressure?

  1. 45 mm Hg Correct answer.
  2. 55 mm Hg
  3. 25 mm Hg
  4. 95 mm Hg

Explanation

Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure. Subtracting 25 from 70 yields 45 mm Hg, which is below the recommended target of 60 to 70 mm Hg.

Question 6Neurotrauma and Critical Care

Which intervention is the most appropriate first-line osmotic therapy for acute intracranial hypertension from traumatic brain injury when serum osmolality is normal?

  1. Furosemide
  2. Mannitol bolus Correct answer.
  3. Hypertonic saline as the sole agent
  4. Dexamethasone

Explanation

Mannitol is the traditional first-line osmotic agent for acute intracranial hypertension; it creates an osmotic gradient that draws water from brain tissue. Hypertonic saline is an acceptable alternative, particularly in hypotension, but mannitol remains a standard initial choice.

Question 7Neurotrauma and Critical Care

A patient with a traumatic brain injury is being monitored for cerebral autoregulation. Over what approximate range of mean arterial pressure does cerebral blood flow normally remain constant in an uninjured brain?

  1. 50 to 150 mm Hg Correct answer.
  2. 180 to 220 mm Hg
  3. 10 to 30 mm Hg
  4. 20 to 40 mm Hg

Explanation

Cerebral autoregulation normally maintains relatively constant cerebral blood flow across a mean arterial pressure range of roughly 50 to 150 mm Hg. Outside this range, flow becomes pressure-dependent, increasing the risk of ischemia or hemorrhage.

Question 8Neurotrauma and Critical Care

Which clinical sign is most suggestive of brain death in a comatose patient with a devastating neurological injury?

  1. Decerebrate posturing to noxious stimuli
  2. Fixed dilated pupils with absent brainstem reflexes Correct answer.
  3. Preserved gag reflex
  4. Spontaneous roving eye movements

Explanation

Brain death requires irreversible coma with absent brainstem reflexes and apnea. Fixed dilated pupils with absent brainstem reflexes is consistent with this state, though formal apnea testing and confirmation of irreversibility are required.

Question 9Neurotrauma and Critical Care

A patient with a severe traumatic brain injury is being ventilated. Which arterial carbon dioxide target is recommended to avoid worsening intracranial pressure while preserving cerebral perfusion?

  1. Aggressive hyperventilation to 20 to 25 mm Hg
  2. Permissive hypercapnia above 50 mm Hg
  3. Normal range of 35 to 38 mm Hg Correct answer.
  4. No specific target is required

Explanation

Normocapnia, approximately 35 to 38 mm Hg, is recommended for most patients with severe traumatic brain injury. Hyperventilation reduces cerebral blood volume and can cause ischemia, while hypercapnia increases intracranial pressure.

Question 10Neurotrauma and Critical Care

A patient with a traumatic brain injury has a decompressive hemicraniectomy performed for refractory intracranial hypertension. Which complication is most specifically associated with this procedure?

  1. Central diabetes insipidus
  2. Loss of corneal reflex
  3. Immediate hydrocephalus requiring shunt placement
  4. Paradoxical herniation through the skull defect Correct answer.

Explanation

Decompressive hemicraniectomy can lead to paradoxical herniation, in which atmospheric pressure and cerebrospinal fluid shifts cause the brain to sag through the defect. This is a recognized complication requiring careful management of CSF drainage and positioning.

Question 11Neurotrauma and Critical Care

Which finding on CT is most consistent with diffuse axonal injury?

  1. Enlarged ventricles with periventricular lucency
  2. Crescentic collection over the convexity
  3. Multiple punctate hemorrhages at the gray-white junction Correct answer.
  4. Large biconvex temporal collection

Explanation

Diffuse axonal injury results from shearing forces and classically produces punctate hemorrhages at the gray-white junction, corpus callosum, and brainstem. These findings may be subtle on initial CT and are better seen on MRI.

Question 12Neurotrauma and Critical Care

A patient with a severe traumatic brain injury develops a serum sodium of 158 mEq/L and high urine output with low urine specific gravity. Which diagnosis is most likely?

  1. Syndrome of inappropriate antidiuretic hormone
  2. Cerebral salt wasting
  3. Osmotic demyelination syndrome
  4. Central diabetes insipidus Correct answer.

Explanation

Hypernatremia with high dilute urine output after severe brain injury suggests central diabetes insipidus from hypothalamic-pituitary dysfunction. Treatment involves fluid replacement and desmopressin when appropriate.

Question 13Neurotrauma and Critical Care

Which cervical spine clearance criterion allows removal of a rigid collar in an alert, asymptomatic trauma patient without imaging?

  1. Glasgow Coma Scale score of 14
  2. Intoxication with alcohol
  3. Presence of midline tenderness alone
  4. NEXUS low-risk criteria Correct answer.

Explanation

The NEXUS low-risk criteria allow clinical clearance without imaging in alert patients who meet all five criteria, including no midline tenderness, no intoxication, and no distracting injury. This avoids unnecessary radiation exposure.

Question 14Neurotrauma and Critical Care

A patient sustains a complete spinal cord injury at the C5 level. Which function is most likely preserved?

  1. Hand intrinsic muscle strength
  2. Triceps extension
  3. Sensation over the umbilicus
  4. Diaphragmatic breathing Correct answer.

Explanation

The phrenic nerve arises from C3 to C5, so diaphragmatic breathing is typically preserved in a C5 injury. Distal upper extremity and truncal functions are lost because their segmental levels lie below the lesion.

Question 15Neurotrauma and Critical Care

Which feature distinguishes neurogenic shock from spinal shock?

  1. Neurogenic shock involves hypotension with bradycardia from loss of sympathetic tone Correct answer.
  2. Spinal shock causes hyperreflexia immediately
  3. Spinal shock involves hypotension with tachycardia
  4. Neurogenic shock causes flaccid paralysis

Explanation

Neurogenic shock results from loss of sympathetic outflow above T6, producing hypotension with bradycardia or lack of tachycardia. Spinal shock refers to the transient loss of reflexes and flaccid paralysis below the injury level.

Question 16Neurotrauma and Critical Care

A patient with a traumatic brain injury and an intracranial pressure monitor has an ICP of 30 mm Hg that is refractory to sedation and osmotic therapy. Which intervention is most appropriate next for refractory intracranial hypertension?

  1. Hyperventilation to a PaCO2 of 30 to 35 mm Hg as a temporizing measure Correct answer.
  2. Aggressive fluid restriction
  3. Routine hyperventilation to 20 mm Hg
  4. Administration of corticosteroids

Explanation

Brief hyperventilation to a PaCO2 of about 30 to 35 mm Hg is a temporizing measure for refractory intracranial hypertension because it reduces cerebral blood volume. It should be used cautiously and for limited periods due to ischemia risk.

Question 17Neurotrauma and Critical Care

Which statement about the Monro-Kellie doctrine is correct?

  1. The intracranial volume is fixed, so increases in one compartment must be offset by decreases in another Correct answer.
  2. Intracranial pressure remains constant regardless of added volume
  3. Cerebrospinal fluid production increases to compensate for mass lesions
  4. The skull expands to accommodate edema in adults

Explanation

The Monro-Kellie doctrine states that the skull is a rigid container with fixed total volume comprising brain, blood, and cerebrospinal fluid. An increase in one component must be compensated by a decrease in another, or intracranial pressure rises.

Question 18Neurotrauma and Critical Care

A patient with a traumatic brain injury has a seizure in the emergency department. Which medication is appropriate for acute seizure control?

  1. Mannitol
  2. Levetiracetam Correct answer.
  3. Naloxone
  4. Dexmedetomidine

Explanation

Levetiracetam is a commonly used antiseizure medication for acute post-traumatic seizures and can be given intravenously. Phenytoin and fosphenytoin are alternatives.

Question 19Neurotrauma and Critical Care

Which factor most strongly predicts outcome after severe traumatic brain injury?

  1. Serum glucose level on admission
  2. Presence of a scalp laceration
  3. Time to CT scan
  4. Pupillary reactivity and motor GCS score Correct answer.

Explanation

Pupillary reactivity and the motor component of the Glasgow Coma Scale are among the strongest early predictors of outcome after severe traumatic brain injury. These bedside findings reflect brainstem integrity and cortical motor function.

Question 20Neurotrauma and Critical Care

A patient with a suspected basilar skull fracture presents with clear rhinorrhea. Which test best confirms that the fluid is cerebrospinal fluid?

  1. Beta-2 transferrin assay Correct answer.
  2. Gram stain of the fluid
  3. Culture of the fluid
  4. Glucose oxidase dipstick alone

Explanation

Beta-2 transferrin is highly specific for cerebrospinal fluid and confirms a CSF leak. Glucose dipstick testing is less reliable because nasal secretions and blood can produce false results.

Question 21Cerebrovascular Surgery

A patient has a sudden severe headache with a CT scan showing blood in the basal cisterns. What is the most likely underlying cause?

  1. Amyloid angiopathy lobar hemorrhage
  2. Ruptured intracranial aneurysm Correct answer.
  3. Hypertensive intraparenchymal hemorrhage
  4. Cerebral venous sinus thrombosis

Explanation

Blood confined to the basal cisterns after a thunderclap headache is the classic pattern of a ruptured saccular aneurysm, most often at the circle of Willis. Venous thrombosis and lobar amyloid hemorrhage produce different distributions, and hypertensive bleeds favor the basal ganglia or thalamus.

Question 22Cerebrovascular Surgery

Which grading scale is most commonly used to stratify the clinical severity of aneurysmal subarachnoid hemorrhage before treatment?

  1. Spetzler-Martin grade
  2. Hunt and Hess Correct answer.
  3. Fisher grade
  4. Glasgow Coma Scale

Explanation

The Hunt and Hess scale classifies clinical condition after subarachnoid hemorrhage and guides prognosis and timing of intervention. The Glasgow Coma Scale is a general consciousness measure, Fisher grade describes CT blood pattern, and Spetzler-Martin grades arteriovenous malformations.

Question 23Cerebrovascular Surgery

A patient with aneurysmal subarachnoid hemorrhage develops hyponatremia on day 3 with elevated urine output and low urine osmolality. What is the most appropriate first-line management?

  1. Isotonic crystalloid volume replacement Correct answer.
  2. Hypertonic saline infusion
  3. Fludrocortisone administration
  4. Fluid restriction

Explanation

This picture is consistent with cerebral salt wasting, in which renal sodium loss produces volume depletion. Treatment is volume repletion with isotonic crystalloid; fluid restriction risks worsening vasospasm and hypoperfusion.

Question 24Cerebrovascular Surgery

What is the main complication that peak on days 3 to 14 after aneurysmal subarachnoid hemorrhage and can cause delayed ischemic deficits?

  1. Rebleeding
  2. Vasospasm Correct answer.
  3. Seizure
  4. Hydrocephalus

Explanation

Delayed cerebral ischemia from vasospasm characteristically occurs between days 3 and 14 after hemorrhage. Rebleeding is most common in the first 24 hours, and hydrocephalus tends to present earlier.

Question 25Cerebrovascular Surgery

Which agent is standard oral prophylaxis against delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage?

  1. Warfarin
  2. Aspirin
  3. Clopidogrel
  4. Nimodipine Correct answer.

Explanation

Nimodipine, a dihydropyridine calcium channel blocker, improves neurological outcome after subarachnoid hemorrhage and is given for 21 days. Antithrombotic agents would increase bleeding risk and are not used for this indication.

Question 26Cerebrovascular Surgery

A patient with a ruptured middle cerebral artery aneurysm undergoes clipping. Which finding on follow-up suggests hydrocephalus requiring treatment?

  1. Small ventricles with slit-like appearance
  2. Hyperdense blood confined to the interpeduncular cistern
  3. Increased cortical sulci
  4. Enlarged temporal horns with transependymal edema Correct answer.

Explanation

Enlarged temporal horns with transependymal flow indicate acute communicating hydrocephalus, often from blood products obstructing arachnoid granulations. This may warrant external ventricular drainage.

Question 27Cerebrovascular Surgery

What is the most common location for a saccular (berry) aneurysm in the cerebral circulation?

  1. Middle cerebral artery bifurcation
  2. Posterior communicating artery
  3. Anterior communicating artery Correct answer.
  4. Basilar tip

Explanation

Anterior communicating artery aneurysms are the most frequently encountered saccular aneurysms overall. Middle cerebral and posterior communicating locations are also common but less frequent.

Question 28Cerebrovascular Surgery

A patient presents with a third nerve palsy and a dilated, nonreactive pupil. What is the most appropriate next step?

  1. Trial of corticosteroids
  2. Emergent CT or catheter angiography Correct answer.
  3. Reassurance and outpatient follow-up
  4. MRI of the brain without contrast

Explanation

A painful or pupil-involving third nerve palsy suggests a posterior communicating artery aneurysm compressing the nerve. Emergent vascular imaging is required to exclude a ruptured or enlarging aneurysm.

Question 29Cerebrovascular Surgery

Which imaging modality is the reference standard for detecting a small aneurysm when noninvasive studies are equivocal?

  1. Transcranial Doppler
  2. CT angiography
  3. MR angiography
  4. Catheter digital subtraction angiography Correct answer.

Explanation

Catheter digital subtraction angiography remains the reference standard with the highest spatial resolution for cerebral aneurysms. CT and MR angiography are excellent screening tools but can miss small lesions.

Question 30Cerebrovascular Surgery

A patient has a Spetzler-Martin grade V arteriovenous malformation. What does this grade primarily predict?

  1. Likelihood of seizure presentation
  2. Response to radiosurgery
  3. Risk of hemorrhage per year
  4. Surgical risk based on size, venous drainage, and eloquence Correct answer.

Explanation

The Spetzler-Martin system combines nidus size, deep versus superficial venous drainage, and eloquence of adjacent brain to estimate surgical risk. Higher grades indicate greater operative morbidity.

Question 31Cerebrovascular Surgery

What is the most common clinical presentation of an unruptured cerebral arteriovenous malformation in adults?

  1. Cranial neuropathy
  2. Progressive dementia
  3. Intracranial hemorrhage
  4. Seizure Correct answer.

Explanation

Seizures are the most frequent presenting symptom of unruptured arteriovenous malformations in adults. Hemorrhage is the most feared complication but is less common as an initial presentation in many series.

Question 32Cerebrovascular Surgery

A patient with a dural arteriovenous fistula has cortical venous drainage. What is the main reason this finding is significant?

  1. It carries an elevated risk of hemorrhage Correct answer.
  2. It excludes the need for treatment
  3. It indicates a benign course
  4. It predicts spontaneous thrombosis

Explanation

Cortical venous drainage in a dural arteriovenous fistula indicates retrograde venous flow and a substantially increased risk of intracranial hemorrhage. Such lesions generally warrant treatment.

Question 33Cerebrovascular Surgery

A patient has a cavernous malformation with a recent symptomatic hemorrhage. What is the most appropriate management for a surgically accessible lesion?

  1. Microsurgical resection Correct answer.
  2. Stereotactic radiosurgery as first-line therapy
  3. Anticoagulation
  4. Observation with serial imaging only

Explanation

Symptomatic cavernous malformations, particularly those with recurrent hemorrhage and accessible location, are best treated with microsurgical resection. Observation is reasonable for asymptomatic lesions, and radiosurgery has limited and delayed benefit.

Question 34Cerebrovascular Surgery

Which feature on MRI is most characteristic of a cavernous malformation?

  1. Perilesional edema out of proportion to size
  2. Ring enhancement with restricted diffusion
  3. Popcorn appearance with a hemosiderin rim Correct answer.
  4. Flow voids on T2

Explanation

Cavernous malformations show a mixed-signal popcorn lesion with a complete hemosiderin rim on T2 gradient-echo or susceptibility-weighted imaging. Flow voids suggest a high-flow arteriovenous shunt.

Question 35Cerebrovascular Surgery

A patient presents with sudden headache, neck stiffness, and a normal noncontrast CT 12 hours after onset. What is the most appropriate next step to evaluate for subarachnoid hemorrhage?

  1. Lumbar puncture for xanthochromia Correct answer.
  2. Repeat CT in 1 week
  3. MRI of the cervical spine
  4. Empiric antibiotics

Explanation

When CT is negative but suspicion for subarachnoid hemorrhage remains, lumbar puncture looking for xanthochromia is the next step. Xanthochromia can persist for days and distinguishes true hemorrhage from traumatic tap.

Question 36Cerebrovascular Surgery

What is the principal advantage of endovascular coiling over surgical clipping for a ruptured aneurysm in an appropriate candidate?

  1. Avoidance of antiplatelet therapy
  2. Less invasive with reduced early morbidity Correct answer.
  3. Lower rate of delayed rebleeding
  4. Higher rate of complete occlusion

Explanation

Endovascular coiling is less invasive and reduces early procedural morbidity compared with open surgery. Clipping may offer more durable occlusion in some lesions, but the early outcome advantage favors coiling in suitable candidates.

Question 37Cerebrovascular Surgery

A patient with a giant cavernous carotid aneurysm presents with progressive visual loss. What is the primary mechanism of the visual deficit?

  1. Retinal artery occlusion
  2. Optic nerve compression Correct answer.
  3. Papilledema
  4. Cortical infarction

Explanation

Giant cavernous carotid aneurysms can expand and compress the adjacent optic nerve or chiasm, producing progressive visual loss. Mass effect, rather than ischemia, is the usual cause.

Question 38Cerebrovascular Surgery

What is the recommended blood pressure target for a patient with an unsecured ruptured aneurysm before definitive treatment?

  1. Permissive hypertension above 180 mmHg systolic
  2. No blood pressure control needed
  3. Aggressive hypotension below 90 mmHg systolic
  4. Controlled normotension or modest hypotension Correct answer.

Explanation

Before the aneurysm is secured, blood pressure is controlled to reduce rebleeding risk while maintaining cerebral perfusion. Extreme hypertension or hypotension is avoided.

Question 39Cerebrovascular Surgery

A patient develops a fixed dilated pupil and rapid deterioration after a large hemispheric infarct. What is the most likely mechanism?

  1. Seizure activity
  2. Hemorrhagic transformation
  3. Malignant cerebral edema with herniation Correct answer.
  4. Hydrocephalus

Explanation

Large hemispheric infarcts can cause malignant edema with mass effect and herniation, producing a fixed dilated pupil. Urgent decompressive surgery may be indicated.

Question 40Cerebrovascular Surgery

Which time window is generally used to select patients for intravenous thrombolysis in acute ischemic stroke?

  1. Within 12 hours of symptom onset
  2. Within 48 hours of symptom onset
  3. Within 4.5 hours of symptom onset Correct answer.
  4. Within 24 hours of symptom onset

Explanation

Intravenous thrombolysis is generally administered within 4.5 hours of symptom onset in eligible patients. Selected patients may benefit from later reperfusion therapy, but the standard thrombolysis window is 4.5 hours.

Question 41Cerebrovascular Surgery

A patient with a middle cerebral artery occlusion presents within 6 hours with a small infarct core and a large penumbra. What is the most appropriate treatment?

  1. Observation with aspirin
  2. Endovascular thrombectomy Correct answer.
  3. Intravenous thrombolysis alone if eligible
  4. Hyperventilation

Explanation

A large vessel occlusion with a small core and large penumbra is the ideal target for endovascular thrombectomy. Thrombectomy improves outcomes in appropriately selected patients with proximal occlusions.

Question 42Cerebrovascular Surgery

A patient has a symptomatic high-grade carotid stenosis. What is the primary rationale for carotid endarterectomy?

  1. Reduce recurrent embolic stroke risk Correct answer.
  2. Improve cognitive function
  3. Treat cerebral vasospasm
  4. Prevent intracranial hemorrhage

Explanation

Carotid endarterectomy reduces recurrent embolic stroke risk in symptomatic high-grade stenosis. The benefit derives from removing the embolic source at the plaque.

Question 43Cerebrovascular Surgery

Which finding suggests a hemorrhagic transformation after ischemic stroke on follow-up CT?

  1. Hyperdensity within the infarcted territory Correct answer.
  2. Ventricular enlargement
  3. Loss of gray-white differentiation
  4. Hypodensity with sulcal effacement

Explanation

New hyperdensity within an infarcted territory indicates hemorrhage on CT. Hypodensity and loss of gray-white differentiation are features of ischemia rather than hemorrhage.

Question 44Cerebrovascular Surgery

A patient with a brain arteriovenous malformation is considering treatment. Which factor most strongly increases the annual hemorrhage risk?

  1. Prior hemorrhage Correct answer.
  2. Superficial venous drainage
  3. Seizure at presentation
  4. Small nidus size alone

Explanation

Prior hemorrhage is the strongest predictor of future hemorrhage in arteriovenous malformations. Other features such as deep venous drainage and associated aneurysms also increase risk.

Question 45Neuro-oncology

A 58-year-old man has a solitary enhancing frontal mass with surrounding edema. Biopsy shows atypical cells with pseudopalisading necrosis and microvascular proliferation. Which WHO grade and tumor type does this represent?

  1. Diffuse astrocytoma, IDH-mutant, WHO grade 2
  2. Pilocytic astrocytoma, WHO grade 1
  3. Oligodendroglioma, IDH-mutant, WHO grade 2
  4. Glioblastoma, IDH-wildtype, WHO grade 4 Correct answer.

Explanation

Pseudopalisading necrosis and microvascular proliferation are the classic hallmark features that define glioblastoma and place it at WHO grade 4. In the current classification, a diffuse astrocytic tumor with these features in an adult is glioblastoma, IDH-wildtype, grade 4.

Question 46Neuro-oncology

Which molecular alteration is required, together with an IDH mutation, to diagnose an oligodendroglioma?

  1. Codeletion of 1p and 19q Correct answer.
  2. ATRX loss
  3. H3 K27M mutation
  4. EGFR amplification

Explanation

The integrated diagnosis of oligodendroglioma requires both an IDH mutation and whole-arm codeletion of 1p and 19q. This combination distinguishes it from IDH-mutant astrocytoma, which instead typically shows ATRX loss.

Question 47Neuro-oncology

A 45-year-old woman has a well-circumscribed dural-based extra-axial mass with a dural tail and homogeneous enhancement. What is the most likely diagnosis?

  1. Meningioma Correct answer.
  2. Schwannoma
  3. Metastatic carcinoma
  4. Hemangiopericytoma

Explanation

A dural-based, homogeneously enhancing extra-axial mass with a dural tail is the classic imaging appearance of a meningioma. Meningiomas arise from arachnoid cap cells and are the most common primary intracranial tumor in adults.

Question 48Neuro-oncology

Which primary brain tumor most commonly metastasizes outside the central nervous system?

  1. Meningioma Correct answer.
  2. Glioblastoma
  3. Ependymoma
  4. Medulloblastoma

Explanation

Although meningiomas are generally benign and slow-growing, they are the primary intracranial tumor most likely to spread systemically, usually to the lungs. Gliomas and medulloblastomas can also spread, but extraneural dissemination is far less common.

Question 49Neuro-oncology

A patient with newly diagnosed glioblastoma has a methylated MGMT promoter. What does this finding most directly predict?

  1. Improved response to temozolomide Correct answer.
  2. Likely long-term cure with surgery alone
  3. Presence of a 1p/19q codeletion
  4. Resistance to radiation therapy

Explanation

MGMT promoter methylation silences the DNA repair enzyme MGMT, reducing tumor cell repair of alkylator-induced damage. This predicts a better response to temozolomide and improved survival in glioblastoma.

Question 50Neuro-oncology

Which tumor is associated with Rosenthal fibers and eosinophilic granular bodies on histology?

  1. Pilocytic astrocytoma Correct answer.
  2. Central neurocytoma
  3. Primary CNS lymphoma
  4. Dysembryoplastic neuroepithelial tumor

Explanation

Rosenthal fibers and eosinophilic granular bodies are characteristic histologic features of pilocytic astrocytoma, a circumscribed WHO grade 1 tumor. These tumors frequently occur in children and often harbor BRAF alterations.