Relevance of basilar artery study in patients with subclavian steal phenomenon.

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.