Can One Predict Persistence beyond Adolescence in Childhood Absence Epilepsy?

BACKGROUND: Although typical childhood absence epilepsy is common and drug-resistance is not uncommon, predictors of drug resistance and its persistence beyond adolescence have not been well studied. OBJECTIVES: To predict recalcitrant childhood absence epilepsy (CAE). MATERIALS AND METHODS: Retrospective data analysis of 153 CAE patients was done. Controlled CAE group (cCAE) had seizure control within 2 years of starting antiseizure medication regimen (ASM) and electroencephalographic (EEG) normalization at <16 years of age. The remaining cohort was classified as drug-resistant CAE group (rCAE). The factors which may affect outcome were analyzed. Seizure freedom was defined as 10 years of clinical seizure-free period with at least 5 years off ASM. RESULTS: Of 153 patients, 104 (67.97%) qualified for cCAE and 79 (75.96%) responded to the first ASM. All in cCAE also achieved seizure freedom. The comparison of initial EEG abnormalities to ASM efficacy proved divalproex sodium (VPA) superiority for patients with poly spike and wave discharges (PSW), Fisher's exact test, P = 0.021, but not ethosuximide (ESM), Fisher's exact test, P = 0.00058; both ASM were equally effective for single spike and wave discharges (SSW); and VPA equally effective for SSW and PSW. Of 49 patients in rCAE, 11 (22.45%) eventually achieved seizure freedom. None in cCAE but 17 (34.69%) in rCAE developed other seizure types which included 9 (18.37%) who developed juvenile myoclonic epilepsy (JME). CONCLUSIONS: The majority of CAE patients attained seizure control over 2 years with EEG normalization before the age of 16 years, and all of them went on to achieve seizure freedom. Almost 3/4th of the patients who are likely to attain seizure control and achieve seizure freedom will do so with the first-line ASM. In addition, ESM should be the first ASM for patients with CAE with SSW, but VPA may be used as the first ASM for patients with CAE with PSW. Furthermore, seizure control and freedom are still possible in some patients with rCAE. Persistent PSW and later development of additional seizure type may predict refractory status and, in some patients, evolving JME.