Long term follow-up of EEG changes following therapeutic surgery in epilepsy.

Four cases, given in some detail, illustrate the effort to compare scalp EEGs taken before surgery for intractable seizures with those recorded some years postoperatively, and to relate these, together with the computer analyses of seizure activity recorded in depth, with the pathology found in the removed tissue and, importantly, with the postoperative clinical state of the patient. These four cases illustrate the following results: (1) Confirmation by histology and ultrastructure studies of abnormal neuronal tissue at the site pinpointed by computer analysis of EEGs as the driving focus for the electrical seizure discharge. (2) Correlation of clinical and behavioral improvement with normalization of the EEG, objectively quantified by computer analysis. Examples are given of excellent recovery (3 cases) and one of, at present, partial recovery.