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Basilar and distal vertebral artery stenosis: long-term follow-up.

Forty-four patients with greater than or equal to 50% stenosis of a distal vertebral artery (VA) and/or basilar artery (BA) were followed up for an average of 6.1 years. Angiography was performed for definite vertebrobasilar (VB) transient ischemic attacks (TIA) in 19 (43%), for VB infarcts in 13 (30%) and for non localizing symptoms in 12 (27%). Stenosis in the BA with or without VA involvement was present in 28 patients (64%), while 16 patients (36%) had occlusive disease in one or both distal VA sparing the BA. In follow up, 7 patients (16%) had definite VB TIA and 3 patients had possible VB TIA. Eight patients (18%) sustained a stroke, 5 of which were in the VB territory. The observed stroke rate was 17 times the expected rate for a matched normal population. Eight patients died during follow up, three patients due to stroke (2 brainstem infarctions, one intraventricular hemorrhage). The observed 5 year survival rate was 78% compared to 90% in a matched normal population. In comparing this data with our previous study of 93 patients with proximal VA occlusive disease, distal VB occlusive disease appears to carry a higher risk for brainstem ischemia.