Abstracts

Lennox-Gastaut syndrome (LGS) is an epilepsy syndrome of early childhood characterized by mental retardation, intractable generalized seizures, and characteristic EEG findings, which typically predicts poor neurologic outcome. As the character and frequency of seizures in LGS can change with development, we investigated evolution of seizure frequency in this patient population over time.
38 patients with strictly defined LGS were identified by query of the UVA Epilepsy Database, containing 1446 patients seen between 1997 and 2003. LGS was defined by clinical criteria and the presence of slow spike and wave on EEG. Clinical characteristics were obtained, including maximum seizure frequency, age at maximum frequency, and current frequency of atonic, tonic, atypical absence and generalized tonic-clonic seizures (GTC) for each subject.
The current age of the study population was 25.4 [plusmn] 15.1 years, and age at seizure onset was 5.29 years. Male:female ratio was 2.8:1. Etiology of LGS was cryptogenic in 66% and symptomatic in 34%. Mean current frequency of all seizure types was 56.3 per month, compared to maximum seizure frequency of 873.2 (p=0.0018). Ten of the 38 LGS patients had a current seizure frequency of less than one seizure per month or were seizure-free. Of the seizure-free patients, six were cryptogenic and four were symptomatic, and had previously averaged 494.2 seizures per month at maximum. For atonic seizures alone, maximal frequency was 71.1 per month and current frequency is 6.31 (p= 0.0004) with 15 of 18 LGS patients currently exhibiting no atonic spells. For tonic seizures, maximal frequency was 174.8 per month and current frequency is 27.1 (p= 0.0226). For atypical absence seizures maximal frequency was 361.2 per month and current frequency is 37.2 (p= 0.0145). For GTC seizures, maximal frequency was 37.7 per month and current frequency is 2.867 (p=0.0051).
Although LGS is associated with poor neurological outcome in the majority of cases, seizure frequency diminishes substantially over time in all seizure types. Further, a significant percentage of LGS patients eventually become seizure free.