Adult Lennox Gastaut syndrome: patients with large focal structural lesions.

Ten patients, referred to the Austin Hospital for possible surgery to alleviate intractable epilepsy, were found to have large local atrophic lesions on CT head scans. Detailed analysis of seizure patterns showed that tonic seizures constituted the main seizure type. In addition the histories of all 10 patients showed absences, atonic seizures and mental deterioration. In half the subjects there were psychomotor elements in some seizures. The clinical diagnosis of Lennox Gastaut syndrome was made. EEG findings were notable for the appearance of bilateral slow spike-wave activity and also tonic seizure fast activity in all patients. Seemingly focal emphasis of abnormal EEG activity, especially spike and spike-wave elements, prompted the use of long-term videomonitoring with intracerebral electrodes in eight patients. In four of these, marked focal emphasis of tonic fast activity in actual seizure recordings provided the basis for local ablative surgery in the expectation of removal of the epileptic focus. In all four cases this surgery was unsuccessful. It would seem, therefore, that though the focal structural lesion and the seizures probably stemmed from the same source, surgery to the lesion did not effect the removal of an 'epileptic focus'. Tonic seizures would seem to be a generalized form of epilepsy and in these patients their presence and the significance thereof were vital to appropriate management.