Vertebrobasilar artery insufficiency and electroencephalogram.

This is a renewed diagnostic approach to vertebrobasilar artery insufficiency (VBI)--a condition which stood in the focus of this author's interest several decades ago. The time for a revisitation has come. The EEG findings consist mainly of generally reduced voltage output and enhanced photic driving response. There is also some theta activity over anterior temporal and midtemporal region, but this finding is common in the early stage of all cerebrovascular disorders. Dysfunction of the pontine portion of the ascending reticular formation might be the cause of the lowered voltage output. The enhanced photic driving might be due to very light hypoxia of the visual cortex.