The Electro-encephalogram in Convulsions Induced by Cardiazol.

SEIZURES induced by cardiazol (pentamethylene tetrazol) are not identical with Grand Mal, but the clinical resemblance is sufficiently close to justify their study by electro-encephalography. Gibbs, Gibbs, and Lennox (1937) have shown conclusively that a genuine epileptic fit is accompanied by a rhythmic, high-potential electrical discharge from the cortex, and Golla, Graham, and Walter (1937) have produced evidence that the majority of young idiopathic epileptics exhibit a focal resting discharge which, by analogy with the slow waves found in the neighbourhood of cerebral tumours (Walter, 1937) have been called " delta foci." Moreover, when an epileptic patient with such a focus has a fit during electro-encephalography, the large waves characteristic of the fit appear first in or near the delta focus and spread thence to the rest of the cortex. Now in the majority of epileptics who show such a focus and complain of frequent major fits, the focus is in the region of the superior frontal gyrus, sometimes on one side only, sometimes on both. This area corresponds roughly with the "Area 6apf" of Vogt, to which Foerster (1936) and others have attributed an "epileptogenic " function. The anatomy and physiology of this part of the cortex and its relation to other parts are not yet sufficiently clear to warrant the adoption of any definite hypothesis, but there is evidence from several sources that this part of the frontal lobe is concerned in some way with the development of convulsive seizures. The possibility of taking records during a series of controlled convulsions induced in the course of treatment of schizophrenic patients at Bexley Hospital seemed an excellent opportunity for collecting information on this matter. The equipment was the same as that used by one of us for the study of cerebral tumours (Walter, 1937). It consists of a three-channel amplifier and triple cathode-ray oscillograph unit ; the amplifiers have balanced input stages and are therefore entirely independent of one another, and the oscillo-graphs have screens with a long after-glow which makes the observation of slow changes easy, if it is not desired to take records. With this apparatus the place of origin of a cortical discharge can be located to within a centimetre or 180