Characterizing chapeau de gendarme in pediatric epilepsy through systematic video-EEG evaluation

Chapeau de gendarme (CdG) is a subtle but clinically relevant semiology that has been scarcely studied in children. Previous studies have primarily focused on its localizing value in small, surgical cohorts. This study aimed to systematically characterize frequency and clinical features of CdG across the pediatric age spectrum.

We retrospectively analyzed video-electroencephalography (EEG) monitoring of 264 children with epilepsy (0-17 years). Up to 10 seizures per type were reviewed per patient. CdG was defined as a symmetrical downward contraction of both mouth corners and chin contraction lasting ≥5 s. CdG characteristics, co-occurring semiologies, and EEG patterns were assessed and compared to the cohort without CdG.

CdG was identified in 28 of 264 patients (10.6%), corresponding to 73 seizures. The median age at first observed CdG was 12.3 years (range 1.3-16.8), with a trend toward increasing frequency in older children. All but one case occurred in focal epilepsies, which were significantly more frequent in the CdG cohort than in those without CdG (p = .009). CdG appeared early in the seizure course (≤5 s in 61.6%) and more often during sleep (p < .001). Hyperkinetic behavior occurred significantly more often in CdG seizures (p < .001). Progression to bilateral tonic-clonic seizures was recorded in 20.5% of CdG seizures (17.9% of patients with CdG) and occurred more frequently in the CdG cohort than in patients without CdG (p < .001). The first ictal scalp EEG pattern most frequently involved the frontal lobe (57.7%).

CdG occurred in a notable proportion of pediatric patients across the entire age range, with a descriptive tendency toward higher occurrence in older children. These findings provide an essential foundation for future investigations exploring developmental and network mechanisms underlying this semiology.