Transcranial Doppler ultrasonography of the basilar artery in patients with retrograde vertebral artery flow

Abstract

Less than 25% of patients with retrograde vertebral artery flow on carotid duplex ultrasonography scan demonstrated a corresponding reversal of flow in the basilar artery. The vast majority of patients do not develop flow reversal in the basilar artery. Provocative maneuvers to increase collateral flow to the arm ipsilateral to retrograde vertebral artery flow did not appear to alter basilar artery flow velocity or direction of flow. Transcranial Doppler ultrasonography is indicated in patients with retrograde vertebral artery flow to document basilar artery flow, especially prior to intervention in patients with symptoms suggestive of posterior cerebral circulation insufficiency.

Transcranial Doppler and Transcranial Color Duplex in Defining Collateral Cerebral Blood Flow

“…A few cases have been documented where a reversal of the BA flow was also seen as a collateral blood flow from the anterior circulation that diverted to the distal subclavian arterial bed. This occurred most often in the presence of contralateral VA stenosis or hypoplasia . However, Harper et al have demonstrated in his study that the intracranial anterior circulation flow via the BA is an infrequent contributor to the collateral blood flow in the distal subclavian artery stenosis or occlusion.…”

“…However, Harper et al have demonstrated in his study that the intracranial anterior circulation flow via the BA is an infrequent contributor to the collateral blood flow in the distal subclavian artery stenosis or occlusion. The majority of blood is diverted from the unaffected VA . Rarely, especially in the presence of contralateral hypoplastic or occulted VA, collateral blood flow can develop from the external carotid artery branches including the occipital, thyrocervical, and costocervical trunks through the muscle branch to the ipsilateral VA .…”

Subclavian Steal Syndrome

“…When the proximal subclavian stenosis is at least moderate (>50%), >90% of patients will have either intermittent or continuous flow reversal in the vertebral artery, 7 though not all will be symptomatic. Duplex ultrasonography and transcranial Doppler appears more sensitive than conventional angiography for detecting flow reversal.…”

Extracranial and Intracranial Sonographic Findings in Vertebral Artery Diseases

“…[63][64][65] In approximately 25% of cases, a carotidobasilar supply with retrograde flow in the basilar artery or a steal effect via the branches of the external carotid artery may be observed. 66 Steal effects vary according to the severity and extent of the SA stenosis or occlusion, as reported by authors who have investigated this effect even by means of the cuff upper arm compression test, which induces reactive arm hyperemia and consequently the steal effect. 21,46 Summarizing, steal effects are divided into 3 grades depending on the severity of the hemodynamic effects 67 :…”