Influence of the Basilar Artery Blood Flow on Vertebrobasilar Ischaemia in the Subclavian Steal Phenomenon: A Transcranial Doppler Study

Abstract

Fifteen patients with a subclavian steal phenomenon were subjected to a neurological examination, ultrasonic duplex scanning, transcranial Doppler ultrasonography and a computerised eye-movement investigation before and after a postischaemic hyperaemia test. Four patients showed symptoms of vertebrobasilar ischaemia. They had very low mean blood flow velocities in the basilar artery before (1 patient) or after (3 patients) postischaemic hyperaemia. In 11 asymptomatic patients, transcranial Doppler revealed normal blood flow velocities in the basilar artery, and the hyperaemia test did not change the basilar-artery blood flow significantly. Transcranial Doppler ultrasonography was useful for the investigation of blood flow velocities in the basilar artery in the subclavian steal phenomenon, and in selecting patients with an insufficient blood flow in the basilar artery provoked by the hyperaemia test. Investigation of eye movements did not improve the diagnostic accuracy.