INI SS Neurosurgery Entrance Exam: Neurovascular Conditions and Vascular Neuroanatomy
Multiple Choice Questions
Question 1: Neurovascular Unit Components
A 45-year-old patient presents with acute ischemic stroke. Understanding the neurovascular unit is critical for comprehending the pathophysiology. Which of the following cell types are NOT considered integral components of the neurovascular unit?
A) Astrocytes and pericytes
B) Endothelial cells and smooth muscle cells
C) Oligodendrocytes and microglia
D) Schwann cells and satellite cells
E) Neurons and adventitial cells
Correct Answer: D
Explanation: The neurovascular unit comprises neurons, glia (astrocytes, microglia, oligodendrocytes), and vascular cells (endothelium, smooth-muscle cells/pericytes, adventitial cells) that are closely related developmentally, structurally, and functionally 1. Schwann cells and satellite cells are components of the peripheral nervous system, not the central neurovascular unit 1.
Question 2: Cerebral Arterial Territories and Stroke Localization
A 62-year-old woman presents with right hemiparesis, hemihypoesthesia, and aphasia. Which arterial territory is most likely affected?
A) Anterior cerebral artery
B) Middle cerebral artery
C) Posterior cerebral artery
D) Basilar artery
E) Anterior choroidal artery
Correct Answer: B
Explanation: Patients with hemiparesis, hemihypoesthesia, aphasia, and spatial neglect should be evaluated for lesions in the middle cerebral artery territory 2. The MCA supplies the largest portion of the lateral cerebral hemisphere, including motor and sensory cortex and language areas 3. Lesions in the MCA territory have a lower rate of complete neurological recovery (50%) compared to other locations (83%) 2.
Question 3: Watershed Infarct Mechanisms
A 68-year-old man with severe bilateral carotid stenosis develops bilateral upper extremity weakness ("man-in-a-barrel" syndrome). Which mechanism best explains this presentation?
A) Cardioembolic stroke
B) Small vessel lacunar infarction
C) Hemodynamic watershed infarction
D) Arterial dissection
E) Venous sinus thrombosis
Correct Answer: C
Explanation: External (cortical) watershed infarcts are located at the junction between superficial territories of major cerebral arteries, with decreased cerebral perfusion in distal regions of vascular territories making these areas vulnerable to ischemia 4. The "man-in-a-barrel" syndrome results from bilateral watershed infarcts between ACA and MCA territories due to severe hypoperfusion 4. Treatment should address the underlying mechanism with optimization of cerebral perfusion and management of carotid stenosis for hemodynamic watershed infarcts 4.
Question 4: Perforating Arteries and Deep Brain Structures
A 55-year-old diabetic patient presents with pure motor hemiparesis affecting the face, arm, and leg equally. MRI shows a small lacunar infarct in the posterior limb of the internal capsule. Which arterial source most likely supplies this region?
A) Anterior cerebral artery cortical branches
B) Middle cerebral artery cortical branches
C) Lenticulostriate arteries from the MCA
D) Anterior choroidal artery
E) Posterior cerebral artery cortical branches
Correct Answer: C
Explanation: Perforating arteries of the anterior circulation arise from the ICA, ACA, MCA, ACoA, and PCoA, and are related to the striatum, thalamus, and basal ganglia 3. The lenticulostriate arteries arising from the MCA supply the internal capsule 3. Patients with small-vessel or lacunar infarcts generally have better survival rates compared to those with other stroke subtypes 4.
Question 5: Circle of Willis Collateral Circulation
During an endovascular procedure, you need to access the left MCA territory, but the left ICA is occluded. Through which anatomical structure can you potentially reach the left MCA via the right ICA?
A) Posterior communicating artery
B) Anterior communicating artery
C) Ophthalmic artery
D) Basilar artery
E) Superior cerebellar artery
Correct Answer: B
Explanation: The Circle of Willis serves as a route to otherwise inaccessible intracranial vascular distributions 5. The ACoA is the core functional anastomosis between the left and right ICA systems 3. Understanding collateral pathways and anastomoses is essential for safe and effective performance of neurointerventional procedures 5.
Question 6: Subarachnoid Hemorrhage and Vasospasm Management
A 52-year-old woman with Hunt and Hess Grade II subarachnoid hemorrhage from a ruptured aneurysm is at risk for delayed cerebral ischemia. What is the recommended nimodipine dosing regimen?
A) 30 mg orally every 6 hours for 14 days
B) 60 mg orally every 4 hours for 21 days
C) 90 mg orally every 8 hours for 10 days
D) 30 mg IV every 4 hours for 21 days
E) 60 mg orally twice daily for 14 days
Correct Answer: B
Explanation: The recommended oral dose of nimodipine is 60 mg (two 30 mg capsules) every 4 hours for 21 consecutive days 6. Oral nimodipine therapy should commence as soon as possible within 96 hours of the onset of subarachnoid hemorrhage 6. Nimodipine has been shown to reduce the severity of neurological deficits resulting from vasospasm in patients who have had a recent SAH 6. DO NOT ADMINISTER NIMODIPINE INTRAVENOUSLY as this can cause clinically significant hypotension 6.
Question 7: Intracranial Atherosclerosis Mechanisms
A 58-year-old patient with symptomatic 70% stenosis of the M1 segment of the MCA presents with recurrent TIAs despite optimal medical therapy. Which mechanism is LEAST likely to explain the ischemic events?
A) Perfusion failure distal to stenosis
B) In-situ thrombosis at the stenotic site
C) Artery-to-artery embolism
D) Branch occlusion of penetrating arteries
E) Cardiac embolism through patent foramen ovale
Correct Answer: E
Explanation: Transient ischemic attacks or ischemic stroke secondary to intracranial cerebral atherosclerosis are caused by four proposed mechanisms: (1) perfusion failure secondary to stenosis and poor collateral circulation; (2) thrombosis at the site of stenosis; (3) thromboembolic events distal to the stenosis; and (4) direct occlusion of a penetrating artery at the site of the plaque 1. Cardiac embolism through a PFO would be a separate cardioembolic mechanism unrelated to the intracranial atherosclerotic stenosis 1.
Question 8: Cerebral Small Vessel Disease and White Matter Changes
A 72-year-old hypertensive patient presents with progressive cognitive decline. MRI shows confluent subcortical white matter hyperintensities (Fazekas grade 3). What is the most appropriate blood pressure target according to current evidence?
A) Systolic BP <140 mmHg
B) Systolic BP <130 mmHg
C) Systolic BP <120 mmHg
D) Systolic BP <110 mmHg
E) No specific target needed
Correct Answer: C
Explanation: Intensive blood pressure control with a target systolic BP <120 mmHg is recommended for individuals over 50 with BP >130 mmHg, as it is the cornerstone of treatment, with evidence showing a linear relationship between lower blood pressure and reduced risk of vascular cognitive impairment 7. Beginning confluent or confluent subcortical white matter hyperintensities are often sufficient to cause clinical cognitive impairment and warrant aggressive treatment 7. White matter hyperintensities should be assessed using a validated visual rating scale such as the Fazekas scale 7.
Question 9: External-Internal Carotid Anastomoses
During preoperative embolization of a meningioma, you must be aware of dangerous anastomoses between the external and internal carotid systems. Which branch of the external carotid artery has the most clinically significant anastomosis with the ophthalmic artery?
A) Superficial temporal artery
B) Middle meningeal artery
C) Internal maxillary artery
D) Occipital artery
E) Ascending pharyngeal artery
Correct Answer: C
Explanation: Key concepts to master include collateral pathways and anastomoses between the external and internal carotid circulation 5. The internal maxillary artery (branch of ECA) has significant anastomoses with the ophthalmic artery (branch of ICA) through the infraorbital and sphenopalatine arteries, which is critical to recognize during embolization procedures to avoid inadvertent embolization of the retinal circulation 5, 8.
Question 10: Vascular Cognitive Impairment Pathophysiology
A 65-year-old patient with multiple vascular risk factors develops progressive cognitive decline. MRI shows extensive white matter disease and multiple lacunar infarcts. Which pathophysiological mechanism is considered pivotal in the early development of cerebral small vessel disease?
A) Amyloid-beta deposition
B) Tau protein hyperphosphorylation
C) Blood-brain barrier dysfunction
D) Synaptic loss
E) Neuronal apoptosis
Correct Answer: C
Explanation: Blood-brain barrier dysfunction plays a pivotal role in the early development of cerebral small vessel disease (cSVD) and represents an important pathophysiological mechanism 7. The neurovascular unit (neurons, glia, and vascular cells) functions as an integrated system, and disruption of this unit contributes to disease progression 7. Mixed pathology (vascular and Alzheimer's) is common, with a prevalence of up to 38% in neuropathologic studies 7.
Question 11: Cerebrovascular Embryogenesis
During fetal development, which gene family is primarily responsible for coordinating vascular patterning and continues to mediate adaptive responses of cerebral capillaries in the adult brain?
A) Notch genes
B) Homeobox genes
C) Sonic hedgehog genes
D) Wnt genes
E) TGF-beta genes
Correct Answer: B
Explanation: Homeobox genes not only coordinate vascular patterning during development, but are also involved in critical adaptive responses of cerebral capillaries in the adult brain, and mediate the microvascular alterations associated with neurodegeneration 1. Studies on the embryogenesis and development of cerebral blood vessels and their interaction with developing neurons and astrocytes are essential for understanding cerebrovascular malformations 1.
Question 12: Genetic Cerebrovascular Diseases
A 45-year-old patient presents with recurrent subcortical strokes and progressive cognitive decline. Family history reveals similar symptoms in multiple generations. MRI shows extensive white matter changes. Genetic testing reveals a NOTCH3 mutation. What is the diagnosis?
A) Fabry disease
B) CADASIL
C) Moyamoya disease
D) MELAS syndrome
E) Hereditary hemorrhagic telangiectasia
Correct Answer: B
Explanation: The study of genes whose mutation leads to diseases of cerebral blood vessels, such as NOTCH3 in CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), is instructive for understanding cerebrovascular pathology 1. These data may help with development of therapies to mitigate the effects of vascular injury and may lead to new therapies for regression or reversal of arteriopathies 1.
Question 13: Spinal Vascular Anatomy
During embolization of a spinal dural arteriovenous fistula, identification of which artery is critical to avoid spinal cord infarction?
A) Posterior spinal artery
B) Artery of Adamkiewicz
C) Anterior radicular artery
D) Posterior radicular artery
E) Vertebral artery
Correct Answer: B
Explanation: Understanding the origin of spinal arterial blood supply is essential for safe neurointerventional procedures 5. The artery of Adamkiewicz (arteria radicularis magna) is the major anterior radicular artery supplying the lower thoracic and lumbar spinal cord, and its inadvertent occlusion during embolization can result in devastating anterior spinal artery syndrome 5, 8.
Question 14: Nimodipine Drug Interactions
A 60-year-old woman with SAH is being treated with nimodipine. She is also taking rifampin for latent tuberculosis. What adjustment to nimodipine therapy is most appropriate?
A) No adjustment needed
B) Increase nimodipine dose and monitor for lack of effectiveness
C) Decrease nimodipine dose due to increased drug levels
D) Discontinue nimodipine immediately
E) Switch to intravenous nimodipine
Correct Answer: B
Explanation: Strong CYP3A4 inducers (rifampin, carbamazepine, phenobarbital, phenytoin, St. John's Wort) should generally not be administered concomitantly with nimodipine as they may significantly reduce nimodipine plasma concentration and efficacy 6. Patients on moderate and weak inducers of CYP3A4 should be closely monitored for lack of effectiveness, and a nimodipine dose increase may be required 6. Nimodipine is metabolized via the cytochrome P450 3A4 system 6.
Question 15: Advanced Neuroimaging for Stroke
A 70-year-old patient presents 8 hours after stroke onset with mild symptoms (NIHSS 4). CT shows no hemorrhage but extensive white matter disease. Which imaging modality is most sensitive for detecting acute ischemic stroke and guiding treatment decisions?
A) CT without contrast
B) CT angiography
C) MRI diffusion-weighted imaging (DWI)
D) MRI T2-FLAIR
E) CT perfusion
Correct Answer: C
Explanation: Diffusion-weighted imaging (DWI) is the most sensitive and specific technique for detecting acute ischemic stroke, with a sensitivity of 88-100% and specificity of 95-100% 2. Computed tomography without contrast is the most commonly used initial modality due to its rapidity and availability, but it has lower sensitivity for small or posterior fossa lesions 2. MRI is recommended over CT for investigating vascular cognitive impairment and monitoring disease progression 7.
Question 16: Cerebrovascular Risk Factor Management
A 58-year-old diabetic patient with a history of lacunar stroke and extensive white matter disease asks about blood pressure targets. What is the most appropriate systolic blood pressure goal?
A) <140 mmHg
B) <130 mmHg
C) <120 mmHg
D) <150 mmHg
E) <110 mmHg
Correct Answer: B
Explanation: Aggressive medical treatment targeting systolic blood pressure <140 mmHg for nondiabetics and <130 mmHg for diabetics has shown benefit in reducing stroke recurrence 4. Management of diabetes mellitus is essential, as it increases the risk of cerebrovascular disease approximately 2 times 7. Antihypertensive therapy should be strongly considered for individuals with average diastolic BP ≥90 mmHg or systolic BP ≥140 mmHg to prevent further progression of microvascular damage 7.
Question 17: Angiogenesis and Neurogenesis
Recent research suggests that newly formed vessels can influence neuronal progenitor fate. Which process is most closely linked to cerebrovascular remodeling after stroke?
A) Apoptosis
B) Neurogenesis
C) Demyelination
D) Gliosis only
E) Calcification
Correct Answer: B
Explanation: There is evidence that newly formed vessels can influence the fate of neuronal progenitors 1. In-depth studies of the relationships between angiogenesis, neurogenesis, and gliogenesis are important for gaining further insight into normal brain development and cerebrovascular malformations 1. Angiogenesis and vascular remodeling studies should be extended to the adult brain to examine the plasticity of the vascular system under different functional demands 1.
Question 18: Moyamoya Disease Pathophysiology
A 35-year-old Asian woman presents with recurrent TIAs and "puff of smoke" appearance on angiography. Which pathophysiological process best characterizes Moyamoya disease?
A) Atherosclerotic stenosis
B) Abnormal collateral vascular development with progressive stenosis
C) Arterial dissection
D) Fibromuscular dysplasia
E) Vasculitis
Correct Answer: B
Explanation: Investigations into microvascular reorganization and remodeling are critical for understanding abnormal collateral vascular development, as seen in Moyamoya disease 1. Angiogenesis and vascular remodeling studies examine the plasticity of the vascular system under different functional demands imposed by brain activity 1. The potential for differences between cerebrovascular cells in large and small blood vessels supplying gray and white matter structures should be explored 1.
Question 19: Intracranial Atherosclerosis Treatment Timing
A 65-year-old patient with symptomatic 80% M1 stenosis had an acute stroke 3 days ago (NIHSS 8). When is the optimal timing for endovascular intervention if medical therapy fails?
A) Immediately (within 24 hours)
B) Acute phase (3-7 days)
C) Subacute to chronic phase (weeks to months)
D) Never, medical therapy only
E) After 1 year
Correct Answer: C
Explanation: Timing of the endovascular intervention is critical in patients with ischemic strokes secondary to intracranial atherosclerosis, with patients in the acute phase having higher stroke-related complications compared with patients in the subacute or chronic phase 1. At present, intervention is generally considered only after failure of adequate medical therapy 1. A team approach by vascular neurologists, neuroendovascular specialists, and neurointensivists should evaluate all patients 1.
Question 20: Vascular Cognitive Impairment Pharmacotherapy
A 75-year-old patient with vascular dementia (MMSE 18) and extensive white matter disease asks about medication options. Which pharmacological agent has the best evidence for cognitive benefit?
A) Memantine 10 mg daily
B) Donepezil 10 mg daily
C) Rivastigmine 6 mg daily
D) Galantamine 16 mg daily
E) No pharmacotherapy is effective
Correct Answer: B
Explanation: Donepezil 10mg has demonstrated the best cognitive benefit among cholinesterase inhibitors, though it also has the highest rate of side effects, with a moderate strength of evidence supporting its use 7. Cholinesterase inhibitors may be considered for individuals with vascular or mixed dementia, with evidence showing small but meaningful benefits in cognitive outcomes 7. Memantine has shown small improvements in cognitive function in individuals with vascular dementia and may be considered as an alternative or adjunct therapy 7.