Cerebrovascular Anatomy and Disease Flashcards

Which segment of the vertebral artery (V1-V4) is most accessible to duplex ultrasound and is the most common site for atherosclerosis?

Answer: V1 - origin from subclavian to C6 transverse foramen

The V1 segment at the vertebral artery origin from the subclavian is the most common site of atherosclerosis and is accessible to duplex imaging.

A patient undergoes carotid endarterectomy (CEA). Intraoperative TCD monitoring detects a sudden drop in MCA mean velocity to below 15 cm/s after cross-clamping. This indicates:

Answer: Cerebral hypoperfusion requiring shunt placement

An MCA mean velocity 50% drop from baseline after carotid cross-clamp indicates inadequate collateral flow and warrants intraoperative shunting.

Hollenhorst plaques seen on fundoscopic examination are cholesterol emboli originating most commonly from:

Answer: Atherosclerotic plaque in the ipsilateral carotid artery

Hollenhorst plaques are refractile cholesterol crystals lodged in retinal arterioles, typically originating from ulcerated atherosclerotic plaque in the ipsilateral ICA.

Which Doppler parameter is most sensitive for detecting a hemodynamically significant stenosis when peak systolic velocity is limited by low cardiac output?

Answer: ICA-to-CCA peak systolic velocity ratio

The ICA/CCA PSV ratio normalizes for cardiac output, making it more reliable than absolute velocity in low-flow states; a ratio >4.0 indicates ≥70% stenosis.

Carotid artery stenting (CAS) post-procedure surveillance with duplex ultrasound uses different velocity thresholds than native vessel criteria because stents:

Answer: Reduce wall compliance and increase velocities, requiring higher threshold cutoffs

Stents reduce arterial wall compliance and produce intrinsically higher peak velocities, necessitating higher PSV thresholds (e.g., >300-450 cm/s for ≥50% in-stent restenosis) compared to native vessel criteria.

In patients with bilateral high-grade ICA stenosis, the CCA waveform may demonstrate which compensatory change?

Answer: Reduced resistance pattern with elevated diastolic flow bilaterally

Bilateral severe ICA disease causes the brain to maximally vasodilate distal resistance vessels, creating a low-resistance high-diastolic pattern in both CCAs.

Which condition causes bilateral vertebral artery flow reversal and is associated with syncope or posterior circulation TIA symptoms triggered by arm exercise?

Answer: Bilateral subclavian steal syndrome

Bilateral subclavian steal causes bilateral retrograde vertebral flow as both upper extremities steal from the posterior circulation during exercise, precipitating symptoms.