Clinical dissection of early onset absence epilepsy in children and prognostic implications

Purpose: To investigate whether patients with typical absence seizures (TAS) starting in the first 3 years of life, conformed to Panayiotopoulos's definition of childhood absence epilepsy (CAE), show different electroclinical course than those not fulfilling CAE criteria.

Methods: In this multicenter retrospective study, we choose a fixed duration follow-up of 36 months to examine the electroclinical course of epilepsy in all children with TAS starting before 3 years of age. The probands who fulfilled Panayiotopoulos's criteria for CAE were classified as having pure early onset absence epilepsy (P-EOAE), whereas those who did not as nonpure EOAE (NP-EOAE). In addition, these two groups of patients were further stratified according to the number of antiepileptic drugs taken to obtain initial seizure control (mono-, bi-, and tritherapy).

Key findings: Patients with P-EOAE (n = 111) showed earlier initial seizure control (p = 0.030) and better seizure-free survival curve (p = 0.004) than those with NP-EOAE (n = 77). No mutation in SLC2A1 gene or abnormal neuroimaging was observed in P-EOAE. Among patients with NP-EOAE, those receiving tritherapy showed increased risk of structural brain abnormalities (p = 0.001) or SLC2A1 mutations (p = 0.001) but fewer myoclonic features (p = 0.031) and worse seizure-free survival curve (p = 0.047) than those treated with mono- and bitherapy. Children with NP-EOAE had 2.134 the odds of having relapse during the follow-up compare to those with P-EOAE.

Significance: Children with early onset TAS who did meet Panayiotopoulos's criteria showed a favorable course of epilepsy, whereas patients not fulfilling Panayiotopoulos's criteria showed increased risk of relapse at long-term follow-up.