Epidemiology and clinical characteristics of frontal absence seizures compared with primary absence seizures

Absence seizures due to secondary bilateral synchrony may be a manifestation of frontal seizures, indistinguishable from primary absence epilepsy (PAE), with a different prognosis and control. There are few epidemiological studies on frontal absences (FAE) in the group of absence epilepsy (AE) in children.

To describe the epidemiology of FAE in childhood and compare the characteristics, clinical evolution, and pharmacological response with PAE.

Retrospective study of cases with AE in children under 14 years of age from 2013 to 2022 in a tertiary hospital. Demographic variables, number, duration and type of associated seizures, frontal EEG focality with and without relation to generalized discharge, pharmacological response and neuroimaging were comparatively studied.

94 patients with a median age of 8.6 years (6-10.1 years; 49M/45H) with AE were included. 84% presented exclusively absence seizures. Hyperventilation induced seizures in 94.2%; photoparoxysms present in 5.3%. They showed EEG focus, 63/94 and in 45/94 it was frontal. In 14/94 (14.8%) the frontal focality preceded the critical spike-wave discharge. The bivariate analysis did not show significant differences in age, time until the consultation, psychomotor development/behavior alteration, association of other types of seizures and triggers. The number of absences/days was significantly lower in the EAFs (p = 0.004) and the need for combination therapy was greater in the bivariate (p = 0.005) and multivariate (p = 0.035) analysis.

FAE represents a significant percentage of AE with seizures of identical morphology, age, and duration, although with fewer seizures/day and a worse response to treatment.