Effect of drugs on discharge characteristics of chronic epileptogenic lesions

Abstract

Chronic epileptogenic lesions were produced in the visual cortex of rabbits. The effect of anticonvulsant agents was measured against the discharge frequency of the spike focus, the threshold to photic activation, and the characteristic patterns of spread. A standard Metrazole (pentetrazole) challenge was used to compare results with those obtained in the more usual pharmacologic assays. Dilantin (phenytoin) did not produce suppression of the primary focus nor did it appear to limit spread to the basal diencephalon or to protect against Metrazole challenge. However, transcortical propagation was effectively limited. Spirodone (naphthalenone hydantoin) demonstrated effective suppression of the primary focus as well as limitation of spread both to basal nuclei and transcortically. Some protection also existed against Metrazole challenge. Tridione (trimethadione) also appeared to suppress the primary focus as well as to limit spread to the basal diencephalon. However, transcortical spread was not effectively limited until the primary focus itself was suppressed. Metrazole protection was the highest of any of the drugs tested. Phenobarbital produced only slight suppression of the primary focus and transcortical spread, good limitation of spread to the basal diencephalon, and good Metrazole protection.