The electroencephalogram and vertebrobasilar artery insufficiency

Abstract

Eeg data were analyzed in 20 patients with the clinical diagnosis of vertebrobasilar insufficiency and 7 patients with mixed vertebrobasilar and internal carotid artery insufficiency. In 2 cases, the course of the illness was fatal. Autopsy studies revealed infarction with basilar artery thrombosis in 1 patient. In the other patient, in spite of brain stem infarction no arterial occlusion was detected. A comparison group consisted of 89 patients with clinical evidence of internal carotid artery or middle cerebral artery insufficiency (or thrombosis). In the vertebrobasilar insufficiency group, 11 out of 20 patients had normal records. In the mixed group, 3 out of 7 patients had a normal eeg. In the comparison group, only 26 out of 89 patients had a normal eeg. In patients with vertebrobasilar artery insufficiency, the prominent eeg feature was the predominance of low-voltage records (16 patients, 80%). Only 10 out of 89 patients with internal carotid artery insufficiency had a generally low voltage tracing (11.2%). Shifting slow and also minor sharp activity over the temporal areas was frequently observed in our patients with the diagnosis of vertebrobasilar insufficiency. Low-voltage records are generally regarded as being "categorically within normal limits". This view is certainly correct unless these records are contaminated by other deviations. However, low-voltage records can be meaningful and informative in the clinical context of vertebrobasilar artery in-sufficiency.