The Lennox-Gastaut Syndrome-An Etiological Consideration

Abstract

The etiology of the Lennox-Gastaut syndrome (LGS) and its relationship to clinical manifestation and prognosis were studied in 125 cases: 30 (24.0%) cryptogenic cases and 95 (76.0%) symptomatic cases
The mental prognosis was significantly more favorable in the cryptogenic group. There was no obvious difference, however, between the cryptogenic group and the symptomatic group in the prognosis for seizures. At the time of follow-up, the cryptogenic group was composed of 11 mentally normal cases (Group C-1) and mentally retarded cases (Group C-2). Seizure prognosis was significantly the best in Group C-1.
EEG topography showed an abnormal increase in the delta band activity in the frontal area in the symptomatic group and in Group C-2, but not in Group C-1. This EEG topography finding indicated the pathophysiological similarity of the symptomatic group to Group C-2, but not to Group C-1. This result was compatible with clinical findings, and it suggests that Group C-1 may be essentially idiopathic.
On the other hand, 50 cases evolving from West syndrome (WS) were significantly less favorable in both mental and seizure prognosis than the remaining 75 cases having no such evolution. Most of the 50 were symptomatic cases and had prenatal etiologies. These findings suggest that the evolution from WS to LGS is important in considering the prognosis of the LGS and that the evolutional change is also related to the etiology.