Lennox-Gastaut syndrome
The Lennox-Gestaut syndrome is classified as an epileptic syndrome shown by the presence of various types of generalized seizures (tonic, atonic and atypical absences) which appear at a certain age (1-8 years), with an interictal EEG showing an abnormally slow basic rhythm interrupted by slow spike-and-wave complexes (< 3 Hz) and progressive mental deterioration. From the aetiological point of view there are cryptogenic (25%) and symptomatic (75%) forms. There is a previous history of West syndrome in 9.4-30% of the symptomatic cases. The commonest types of seizures are tonic (17-95%), atypical absences (17-60%) and atonic (25-56%). The mixed form of an epileptic state with typical absences and tonic seizures is the most frequent (27%). Follow-up studies show that in 90% and 100% of cryptogenic and symptomatic patients, respectively, mental retardation develops and the initial seizures persist in 67% and 45% of the patients with cryptogenic and symptomatic forms respectively, when they become adults. There is still no successful treatment for these seizures and progressive mental deterioration occurs even when using the newer anti-epileptic drugs. Electrical stimulation of the vagus nerve seems a promising possibility but further experience is necessary.