Abstracts

Rationale: While previous studies have documented the efficacy of lamotrigine as monotherapy in typical childhood absence seizures, the studies did not examine whether pre-treatment characteristics of the children were predictive of response rate. The objective of this analysis was to compare characteristics of responders and non-responders to lamotrigine in children with newly diagnosed typical absence epilepsy.Methods: Children ranging in age between 3-13 years meeting enrollment criteria (n=54) as demonstrated by generalized spike-wave discharges (2.5-4.5 Hz) lasting > 3 seconds on a 1-hour electroencephalogram (EEG), underwent a 24-hour ambulatory EEG and then entered an Escalation Phase (≤20-weeks) during which the lamotrigine dose was titrated until seizures were controlled or maximum dose was reached. For this study, a patient was considered a responder if they had no absence seizures for two consecutive weeks as confirmed by hyperventilation for clinical signs and 1-hour EEG. Patients responding to treatment then underwent a repeat 24-hour EEG.Results: Of the 54 patients evaluated, 30 (56%) were responders (seizure-free) while 24 (44%) did not achieve seizure freedom. There were no differences in mean age (responders 7.2±2.6 years; non-responders 7.5±2.9 years), baseline weekly seizure count (responders 6.0±2.1 seizures; non-responders 6.1±2.3 seizures), baseline seizure number on the pre-treatment 24-hour EEG (responders 57.8±49.3 seizures; non-responders 63.7±51.4 seizures), and baseline total seizure duration on the pre-treatment 24-hour EEG (responders 532.5±436 seconds; non-responders 662.8±467.8 seconds). There were no significant differences in responder rate between the young children (3-7 years, n=24; 50% response rate) and older children (8-13 years, n=25; 62% response rate).Conclusions: Lamotrigine was effective in suppressing absence seizures in newly diagnosed patients. Age of seizure onset, frequency and duration of absence seizures as measured on the pre-treatment 24-hour EEG was similar in the responders and non-responders. In this large cohort of drug naïve patients with typical childhood absence seizures, the response rate to lamotrigine was not influenced by age of onset, seizure frequency or seizure duration.