Spastic constriction of cerebral vessels after electric convulsive treatment

The brains of nine cats were subjected to bitemporal electric convulsive treatment. The current (AC, 220 V, 50 Hz, ca. 500 mA, 500 ms) was applied two to five times. Pial vessels were observed through a skull window. Immediately after current application, some pial arteries exhibited segmental spastic constriction which usually did not disappear until the animals were killed. Before sacrificing the animals, 20 min after convulsive treatment they were perfused with a carbon suspension. In some cortical areas blackening was impaired indicating that perfusion was not complete. Electron-microscopic investigation revealed that spasm also occurred in arterioles of the brain parenchyma. Many arterial vessels, some of them possessing only one muscular cell sheat, had collapsed so that the lumen was merely a small cleft. The spasms were irregularly distributed and confined to small segments of the vessel. Small arteriolar vessels were more affected than large pial arteries. Arterial spasms continued for 20 min. In a total of 39 control animals spastic constriction was observed only once; this animal had been subjected to prolonged hypocapnia.