The Electroencephalogram in Traumatic Epilepsy.

THE material used in earlier studies of the immediate and remote effects of injury upon the human e.e.g. (Williams, 1941 (a) and (b)) gave little information upon the relationship of these effects to the development of traumatic epilepsy. In the three years which have since elapsed much more data have been accumulated on traumatic epilepsy, and more definite conclusions than were possible at that time can be made on this aspect of the subject. Other papers upon the general and focal changes in the e.e.g. associated with trauma have been published (Jasper, Kershman and Elvidge (1940) and Heppenstall and Hill (1943), and Jasper and Penfield (1943) have described changes associated with traumatic epilepsy. Reporting upon 81 patients studied by the e.e.g., of whom 32 had had a cerebral operation, they described focal abnormality in 90 per cent., with a generalized disturbance in the remainder. The most characteristic change in the e.e.g. in these cases was the presence of highvoltage spikes, although slower waves were also seen, and the authors commented upon the close association of the position of the observed cerebral lesion in the 32 operated cases, and the site of focal discharge in the e.e.g. They thought that the 10 per cent. of patients who did not show such a focus may have been suffering from essential, rather than traumatic, epilepsy. The importance of trauma in causing focal changes in the e.e.g. has also been established by Gibbs, Merritt and Gibbs (1943). The present enquiry is not so much concerned with the focal nature of the changes in the e.e.g. in traumatic epilepsy as with the relationship of different abnormalities in the e.e.g. of patients with head injuries to the subsequent onset of traumatic epilepsy. Evidence based on the observation of a large number of subjects will be presented, and this evidence will be related to the possibility of predicting the onset of traumatic epilepsy by means of electroencephalographic examination.