A Clinical Study of Seventy Adult Patients with the Lennox-Gastaut Syndrome

Abstract

The clinical characteristics of 70 adult patients with the Lennox-Gastaut syndrome were analysed and compared with those of 103 control group patients who were below the age of 16 and also with the Lennox-Gastaut syndrome. In the adult group, most patients (83%) had their onset seizures after age 8 and a small number of patients (13%), before age 6. The mean age at the onset of epileptic seizure was 11 ±5 (s.d.) years. In the control group, most patients (91%) had their first seizures before age 6 and a very small number of patients (4%), after-age 8. The mean seizure onset age was 2.5 ±2.1 years. The presumed mean age at the beginning of the Lennox-Gastaut syndrome was 17 ±6 years in the adult, and 4.5 ±2.8 years in the control group. The most frequently observed seizure types in the adult patients were: tonic, atypical absence, atonic and astatic seizures. These seizures were commonly resistant to the current antiepileptic drugs. Rather high abnormalities (80%) were found in CT compared with other authors' reports, most common of which was diffuse cerebral atrophy. EEG findings showed normal background activity in 46% and focal abnormalities in 29% of the adult patients. The epileptic recruiting rhythm and the low voltage fast activity were found in 87% of them. It is concluded that the adult patients with the Lennox-Gastaut syndrome can be classified into two forms: early onset form before age 6 and late onset form after age 8. A large number of the adult patients belong to the late onset. form and only a small number of them to the early onset form which is most commonly seen in children. Thus, the Lennox-Gastaut syndrome should be classified into two in terms of etiological backgrounds: those due to the age-dependent epileptic encephalopathy and to the non-age-dependent epileptic encephalopathy (late onset form). © 1983, JAPAN EPILEPSY SOCIETY. All rights reserved.