Therapeutic Outcomes and Prognostic Factors in Childhood Absence Epilepsy

Abstract

Background and purpose: Childhood absence epilepsy (CAE) is one of the most common types of pediatric epilepsy. It is generally treated with ethosuximide (ESM), valproic acid (VPA), or lamotrigine (LTG), but the efficacy and adverse effects of these drugs remain controversial. This study compared initial therapy treatment outcomes, including VPA-LTG combination, and assessed clinical factors that may predict treatment response and prognosis.

Methods: Sixty-seven patients with typical CAE were retrospectively enrolled at the Korea University Medical Center. We reviewed patients' clinical characteristics, including age of seizure onset, seizure-free interval, duration of seizure-free period, freedom from treatment failure, breakthrough seizures frequency, and electroencephalogram (EEG) findings.

Results: The age at seizure onset was 7.9±2.7 years (mean±SD), and follow-up duration was 4.4±3.7 years. Initially, 22 children were treated with ESM (32.8%), 23 with VPA (34.3%), 14 with LTG (20.9%), and 8 with VPA-LTG combination (11.9%). After 48 months of therapy, the rate of freedom from treatment failure was significantly higher for the VPA-LTG combination therapy than in the three monotherapy groups (p=0.012). The treatment dose administrated in the VPA-LTG combination group was less than that in the VPA and LTG monotherapy groups. The shorter interval to loss of 3-Hz spike-and-wave complexes and the presence of occipital intermittent rhythmic delta activity on EEG were significant factors predicting good treatment response.

Conclusions: This study showed that low-dose VPA-LTG combination therapy has a good efficacy and fewer side effects than other treatments, and it should thus be considered as a firstline therapy in absence epilepsy.

Keywords: absence seizures; epilepsy; lamotrigine; prognostic factors; valproic acid.

Fig. 1. Freedom from treatment failure in the four medication groups. After 48 months of therapy, the rate of freedom from treatment failure differed significantly between medication groups (p=0.012). The rates of freedom from treatment failure were 100% and 45.5%, respectively. The odds ratio for freedom from treatment failure for the VPA-LTG combination group was 2.20 vs. ESM [95% confidence interval (CI)=1.39-3.47, p=0.010], 1.28 vs. VPA (95% CI=1.03-1.58, p=0.291), and 2.00 vs. LTG (95% CI=1.18-3.38, p=0.022). ESM: ethosuximide, LTG: lamotrigine, V+L: valproate+lamotrigine, VPA: valproate.