Lennox-Gastaut's syndrome--prognosis of the secondary generalized epilepsies

On 62 cases with Lennox-Gastaut's syndrome aged four to 31, the clinical-electroencephalographic findings were summarized as follows; (1) Age of onset was over 10 years in 10 cases (16.1%). (2) Mental deficiencies were more severe in those with onset earlier than age three. (3) Behavioral problems were observed in 34 cases (54.8%); 21 with hyperactive and 13 with hypoactive ones -- 18 hyperactive cases (85.7%) with the onset taking place before age six, and 12 hypoactive cases (92.3%), all whose age is now over 10. (4) The number of clinical seizures showed a tendency in which monoictal manifestation decreased from 25 to three whereas polyictal one increased from 13 to 59 cases during the course of a decade. (5) Interictal EEG findings were pseudorhythm of slow spike-wave with or without focal spikes, and so-called runs of rapid spikes during sleep recording. Focal spikes were observed in 25 cases (40.3%); mainly in the frontal area among those under 10 years old, and in the anterior temporal area among those over 20. The rapid spikes were demonstrated in 19 cases (30.6%) in the over-15 age group and appeared to be correlated with epileptic drop seizures and atypical complex absences.