The effect of intracarotid amobarbital injections upon experimentally induced epileptiform activity

Abstract

The effects of intracarotid amobarbital injection upon penicillin-induced epileptogenic foci were studied in monkeys and cats. Injection volumes and rates were adjusted in such a manner as to ensure selective perfusion of the vascular territory of the injected artery. Cortical epileptiform activity was depressed whenever the focus was perfused by the amobarbital, except for cingulate foci, which were resistant to the amobarbital under the usual experimental conditions of slight hypocapnia. However, 5% CO 2 breathing restored the responsiveness of cingulate foci to the depressant action of intracarotid amobarbital injection. The activity of epileptic foci in the mesial and inferior portion of the temporal lobe was not depressed by intracarotid amobarbital, since this area is irrigated by the posterior cerebral artery. Cortical foci outside, but near the border of the perfused area, sometimes showed activation of epileptiform discharge in response to intracarotid amobarbital injection. Most attempts to create subcortical epileptogenic foci and to test their response to intracarotid amobarbital were unsuccessful and whenever epileptiform activity was obtained there was evidence that it might have been due to seepage of the penicillin into CSF-containing spaces or neighbouring cortex. Diffuse epileptiform activity induced by intraventricular penicillin injection or intravenous chlorambucil administration was not significantly affected by intracarotid amorbarbital injection.