Smooth muscle EMG in cerebral vasospasm: experimental and clinical study

Abstract

Electric action potentials accompanying cerebral vasoconstriction and vasodilatation were observed in the exposed basilar artery of the cat. Spontaneous discharges were recognized at the beginning of either constriction or dilatation of blood vessels with a frequency of once every 5 to 10 seconds. Spontaneous discharges from the smooth muscle of the parent artery near a ruptured aneurysm were clinically observed in 21 patients after aneurysm neck clipping. These patients were operated on from 3 to 30 days after the attack. Cerebral angiography was done either on the day of operation or on the day before. In cases where vasospasm was not seen with angiography, spontaneous discharges ranging from 30 to 100 μV were encountered once every 3 to 15 seconds. When stimulation with either cold or warm water was given to the blood vessel, action potentials were observed at a frequency of 5 to 6 discharges every 10 seconds. In cases with late vasospasm however, both spontaneous discharges and action potentials caused by water stimulation decreased. In cases where vasospasm was reduced at the time of an intentionally delayed operation, a remarkable reduction of action potentials was noted. Late vasospasm may be concerned not only with smooth muscle constriction, but also with some quite different mechanism.