EFFECT OF SUBCLAVIAN SYNDROME ON THE BASILAR ARTERY

Fifty-five patients with a permanent or intermittent subclavian steal syndrome demonstrated by continuous wave Doppler were included in a pr ospective study: 25 patients without vertebro-basilar symptoms, 8 symp tomatic patients with defined vertebro-basilar symptoms and 22 with he modynamic vertebro-basilar occurences. The basilar artery velocity was recorded by Transcranial Doppler Sonography in baseline conditions, a nd after a hyperaemia test to the upper limb. A spontaneous, incomplet e basilar steal was diagnosed in seven patients, and a complete basila r steal in one patient, (14.5% of the cases). After hyperaemia test, 1 8 other incomplete basilar steal were observed. The occurence of a bas ilar steal was higher in the vertebro-basilar group (57% of the cases) especially in 7 of the 8 cases with defined vertebro-basilar symptoms ; it was lower in the patients without vertebro-basilar occurences (36 % of the cases). This basilar steal was also seen in five of the six s ymptomatic patients with opposite vertebral artery stenosis above a 50 % diameter. Transcranial Doppler Sonography could help to define a sub group of subclavian steal syndrome with a high risk of strokes.