The Effect of Cholin-Like Substances on the Cerebral Electrical Discharges in Epilepsy

Abstract

(RECEIVED 11TH MARCH, 1941) IN a recent paper (Williams and Russell, 1941) the effects of anticholinesterases on petit mal epilepsy were described. Clinical and subclinical attacks were recorded on the electro-encephalogram (e.e.g.) in epileptic subjects who were selected either for the frequency of their spontaneous attacks, or for the ease with which attacks could be induced. A dose of eserine insufficiently large to cause symptoms through its effect on the parasympathetic system in man was found to prevent petit mal activity, whereas a larger dose caused an increase in the number and duration of petit mal attacks. Prostigmin on the other hand invariably caused an increase in the epileptic activity seen in the e.e.g. and it reversed the effect of small doses of eserine. The work has been continued in an attempt to establish the mode of action of these drugs and to discover the effect of other substances known to modify transmission at cholinergic endings. The present paper contains observations on the effect of acetylcholine and allied drugs upon the incidence of epileptic cerebral discharges, and the results are discussed in relation to the site of action of the substances. MethodsAs the experimental procedure did not differ greatly from that already described (Williams and Russell, 1941) it will only be referred to briefly. Epileptic patients and normal subjects were used. They sat or lay comfortably at rest with the eyes closed while an e.e.g. record was obtained from two solder electrodes sealed to the scalp over the frontal and parietal lobes with collodium simplex, contact being made with Cambridge electrode jelly. The electrodes led to a condenser coupled amplifying system which was connected to a Grass ink writing oscillograph. This recorded the difference in electrical potential between two widely separated areas of the cortex, and as the cerebral electrical changes associated with clinical fits involve the whole cortex and those seen in subclinical attacks are usually propagated over a wide area, this method of recording proved adequate for the investigation, which only dealt with the number and duration of attacks. Time was recorded in seconds and minutes and in some cases electrocardiographic and respiratory tracings were made simultaneously with the e.e.g. The experimental procedure and clinical signs and symptoms were noted on the moving record as they occurred.