Abstracts

Lennox-Gastaut syndrome (LGS) is an epilepsy syndrome of childhood characterized by intractable generalized seizures, mental retardation, and slow spike-wave EEG findings. LGS is typically associated with poor neurologic outcome, however recent data suggest that some patients do well. To assess the prognosis of LGS we investigated the proportion of LGS patients who become seizure free and the duration of seizure freedom. 46 patients were identified from the UVA Epilepsy Database who were coded as LGS and were confirmed to have generalized seizures, mental retardation, and slow spike-wave on at least one EEG. The database was queried to determine maximum, minimum and current seizure frequency for all seizure types including atonic, tonic, atypical absence, and generalized tonic clonic (GTC) seizures. For those with current seizure frequency of zero, the duration of seizure freedom was obtained from chart review. The average age of the 46 patients meeting LGS criteria is 26.5 years. Average age of seizure onset is 3.22 years. Male:female ratio is 1.88:1. Etiology of LGS is symptomatic in 34.8% and cryptogenic in 65.2%. Mean current seizure frequency for all seizure types is 62.5 per month. Eight of the 46 LGS patients (17.4%) are currently seizure free. Average length of seizure freedom in these patients is 33.8 months (range 3-157 months), and 5 have been seizure free for greater than one year. Average age of the seizure free patients is 28.0 years and 62.5% are cryptogenic. The youngest seizure free patient is 7 years. For all LGS patients in the database, maximal atonic seizure frequency is 84.0 seizures per month and current frequency is 2.57 seizures per month (p=0.0008). For tonic seizures, maximal seizure frequency is 191.1 seizures per month and current frequency is 24.1 seizures per month (p=0.0015). For atypical absence seizures, maximal seizure frequency is 383.4 seizures per month and current frequency is 46.7 seizures per month (p=0.0114). For GTC seizures, maximal seizure frequency is 40.3 seizures per month and current frequency is 3.25 seizures per month (p=0.0003). The frequency of seizures in LGS diminishes substantially over time in some patients with many patients becoming seizure free for long periods. The data suggest that the natural history of LGS is not uniformly severe.