Vascular supply (Circle of Willis) — MCQs

A 38-year-old woman with moyamoya disease undergoes cerebral angiography showing bilateral progressive stenosis of distal internal carotid arteries with extensive collateral formation. She has had multiple TIAs despite medical management. CT perfusion shows reduced flow in bilateral MCA territories. The neurosurgery team debates between direct bypass (STA-MCA) versus indirect revascularization (EDAS). Evaluate the optimal approach considering Circle of Willis pathophysiology.

A 70-year-old man undergoes elective clipping of an unruptured basilar tip aneurysm. Preoperative angiography shows bilateral fetal-type posterior cerebral arteries (PCAs arising from internal carotid arteries) with hypoplastic P1 segments. The aneurysm involves both posterior communicating artery origins. Synthesize an approach to surgical planning that optimally preserves cerebral perfusion.

A 42-year-old woman presents with progressive cognitive decline, early-onset dementia, and recurrent subcortical strokes. Genetic testing reveals CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy). MR angiography shows no large vessel abnormalities but extensive white matter changes. Her sister, also affected, is considering pregnancy. Evaluate the counseling regarding Circle of Willis anatomy and implications for disease manifestations.

A 55-year-old man with diabetes and hypertension undergoes carotid endarterectomy for critical left internal carotid stenosis. Postoperatively, he develops right homonymous hemianopia without motor deficits. Intraoperative transcranial Doppler had shown reduced flow in the ipsilateral middle cerebral artery but preserved anterior cerebral artery flow. Analyze the most likely mechanism for this specific deficit pattern.

A 28-year-old woman presents with bilateral lower extremity weakness worse than upper extremity weakness, abulia, and urinary incontinence. MRI reveals bilateral anterior cerebral artery territory infarcts. Angiography shows an azygos anterior cerebral artery variant. Analyze the anatomical basis for this patient's bilateral deficits from a presumed single vascular occlusion.

A 65-year-old woman with hypertension develops sudden vertigo, dysphagia, and loss of pain and temperature sensation on the left face and right body. MRI shows a left lateral medullary infarct. Analysis of her vascular anatomy reveals an incomplete Circle of Willis. Which specific arterial segment occlusion best explains this clinical presentation?

A 34-year-old woman presents with thunderclap headache and is found to have subarachnoid hemorrhage. Angiography reveals an anterior communicating artery aneurysm. During surgical clipping, the surgeon must be most cautious about preserving which small perforating vessels that arise from this region?

A 45-year-old man undergoes cerebral angiography that reveals hypoplasia of the right posterior communicating artery. During the procedure, the left vertebral artery is inadvertently occluded. Which vascular territory is most at risk for ischemia given this anatomical variant?

A 72-year-old man with atrial fibrillation presents with sudden onset right-sided weakness and aphasia. MRI reveals an acute infarct in the left middle cerebral artery territory. Given the Circle of Willis anatomy, which collateral pathway would most likely provide blood flow to the affected territory if the left internal carotid artery were severely stenotic?

A 58-year-old woman presents to the emergency department with sudden onset of severe headache, vomiting, and loss of consciousness. CT angiography reveals a saccular aneurysm at the junction of the posterior communicating artery and internal carotid artery. Which nerve structure is most likely to be compressed by this aneurysm if it expands?