Neurologists Exam Cerebrovascular Disease & Stroke 2 — Questions and Answers
Question 1: Which neuroimaging modality has the highest sensitivity for detecting acute ischemic stroke within the first 6 hours of onset?
- Non-contrast CT scan
- MRI diffusion-weighted imaging (DWI) (Correct answer)
- CT perfusion with contrast
- Conventional cerebral angiography
Correct answer: MRI diffusion-weighted imaging (DWI)
MRI DWI detects cytotoxic edema (restricted diffusion) within minutes of ischemic onset and has >95% sensitivity for acute ischemia, far exceeding CT which is primarily used to exclude hemorrhage.
Question 2: On non-contrast CT, acute intraparenchymal hemorrhage appears as:
- A hypodense (dark) region
- A hyperdense (bright) region (Correct answer)
- An isodense region indistinguishable from normal brain
- A ring-enhancing lesion
Correct answer: A hyperdense (bright) region
Acute blood appears hyperdense (bright white) on non-contrast CT due to the high protein content of clotted hemoglobin, typically 55–90 Hounsfield units.
Question 3: The 'hyperdense MCA sign' on non-contrast CT in acute stroke represents:
- Early cytotoxic edema in MCA territory
- Acute thrombus within the middle cerebral artery lumen (Correct answer)
- Calcification of the MCA wall
- Contrast enhancement from blood-brain barrier breakdown
Correct answer: Acute thrombus within the middle cerebral artery lumen
The hyperdense MCA sign reflects acute thrombus within the MCA lumen, which appears denser than surrounding brain tissue, and is an early CT indicator of large vessel occlusion.
Question 4: In acute stroke perfusion imaging, the 'penumbra' is defined as:
- The irreversibly infarcted core with absent perfusion
- The ischemic but potentially salvageable tissue surrounding the infarct core (Correct answer)
- The area of luxury perfusion after successful reperfusion
- The zone of cortical spreading depolarization adjacent to the infarct
Correct answer: The ischemic but potentially salvageable tissue surrounding the infarct core
The ischemic penumbra is metabolically compromised but structurally intact tissue surrounding the infarct core; it remains viable temporarily and is the target of reperfusion therapy.
Question 5: Which cardiac condition is the most common identifiable cause of cardioembolic stroke?
- Mitral stenosis with rheumatic heart disease
- Patent foramen ovale
- Atrial fibrillation (Correct answer)
- Dilated cardiomyopathy with reduced EF
Correct answer: Atrial fibrillation
Atrial fibrillation accounts for approximately 15–20% of all ischemic strokes and is the most common identified cardiac source of cerebral emboli, particularly in older patients.
Question 6: A patient presents with sudden onset 'thunderclap' headache described as 'the worst headache of my life.' What is the most urgent diagnosis to exclude?
- Complicated migraine with aura
- Subarachnoid hemorrhage (SAH) (Correct answer)
- Hypertensive urgency headache
- Cerebral venous sinus thrombosis
Correct answer: Subarachnoid hemorrhage (SAH)
A sudden-onset severe 'thunderclap' headache is subarachnoid hemorrhage until proven otherwise; CT without contrast is the first-line test, followed by lumbar puncture if CT is negative.
Question 7: The ABCD2 score after a transient ischemic attack (TIA) is used to:
- Determine eligibility for IV thrombolysis
- Stratify short-term risk of subsequent stroke to guide urgency of workup (Correct answer)
- Score disability at hospital discharge
- Classify stroke etiology by mechanism
Correct answer: Stratify short-term risk of subsequent stroke to guide urgency of workup
The ABCD2 score (Age, Blood pressure, Clinical features, Duration, Diabetes) stratifies early stroke risk after TIA; higher scores indicate greater urgency for hospitalization and expedited workup.
Neurologists Exam Cerebrovascular Disease & Stroke 2
Which neuroimaging modality has the highest sensitivity for detecting acute ischemic stroke within the first 6 hours of onset?