Relevance of basilar artery study in patients with subclavian steal phenomenon

Abstract

A 72-year-old male presented to the emergency department with gait instability and unclear speech. Computed tomography of the brain showed old lacunar infarcts in basal ganglia. Transcranial Doppler (TCD) sonography was normal. Extracranial Duplex sonography showed indirect hemodynamic signs of bilateral subclavian artery stenosis and both vertebral arteries also showed delayed systolic flow increase. A bilateral subclavian steal phenomenon was suspected, and arm compression tests was performed. The tests promoted reverse flow in the right VA, loss of diastolic flow in the left VA and interestingly, the normal anterograde BA flow became retrograde. Although subclavian steal is likely to be an innocuous phenomenon for the majority of our patients, it is probable that the presence of a hemodynamic effect on the basilar artery may identify those who are at special risk of neurologic symptoms. So, we recommend TCD study in all patients suffering SSP to rule out the possibility of a BA steal phenomenon.

Keywords: Subclavian steal; basilar steal; cerebrovascular disease; transcranial doppler ultrasound; vertebro-basilar symptoms..

Fig. (1)

Extracranial color Duplex study of vertebral arteries before (left side), during (middle position), and upon completion (right position) of the arm compression test. Right VA (upper images) reveals initial anterograde flow that became retrograde after cuff release. Left VA (lower images) also shows initial anterograde flow with loss of diastolic flow at the end of the test.

Fig. (2)

Basilar Steal Phenomenon. Normal basilar flow converted to retrograde flow upon release of the blood-pressure cuff. Basilar flow is initially anterograde. Following the ischemia test, the basilar artery shows minimal and retrograde flow.