Evolution of Lennox-Gastaut syndrome: a long-term longitudinal study.

In 102 patients with Lennox-Gastaut syndrome (LGS) observed for an average of 16 years (range, 10-20 years), 12 of the patients worked normally, 36 worked part-time or at a sheltered workshop, and most of the remaining 54 were under home care or institutionalization. LGS evolved from West syndrome or from unspecified epilepsies, or as the primary form, mostly in childhood and rarely in adolescence or adulthood. At the worst stage, there were diverse types of generalized seizures, slow spike-and-wave EEG complexes, fast rhythms, and multiple spike-and-wave complexes. Mental subnormality progressively worsened. Characteristic symptoms of LGS continued in one third of patients, and various abortive forms of LGS were seen in the other two thirds, although LGS did not evolve into a localization-related epilepsy during the survey period. The evolution of seizure and EEG epileptic discharges suggests that LGS has a characteristic clinical course as it progresses. The persistent generalized tonic seizures of various magnitude over a long time in the vast majority of patients indicate that the brainstem rather than the cortical mantle is involved as the seat of seizure-generating mechanisms in LGS.