Gender and age influence in daytime and nighttime seizure occurrence in epilepsy associated with mesial temporal sclerosis

ObjectivesThe aim of this study was to analyze the daytime and nighttime seizure distribution during video-EEG monitoring in patients with epilepsy associated with unilateral mesial temporal sclerosis (MTS) and the role of gender, age, and lesion side on 24-hour seizure distribution.MethodsWe studied 167 consecutive adult (age ≥ 16 years) patients with epilepsy associated with unilateral mesial temporal sclerosis that had three or more recorded seizures during continuous video-EEG monitoring with a minimum recording time period of 24 h. Seizure onset time was classified according to occurrence in six 4-hour periods.ResultsSeven hundred thirty-five seizures were evaluated. We observed two higher seizure occurrence periods: 08:01–12:00 (p = 0.001) and 16:01–20:00 (p = 0.03). Significantly fewer seizures were observed between 0:01 and 4:00 (p = 0.01). Nonuniform seizure distribution was noted in women (p < 0.0001), in young patients (less than 45 years of age) (p < 0.0001), and in both patients with left (p = 0.03) and patients with right mesial temporal sclerosis (p = 0.008). Men presented uniform seizure occurrence distribution (p = 0.15). Women had fewer seizures than expected and fewer seizures than men between 0:01–04:00 (p < 0.0001 and p = 0.0015, respectively) and 04:01–08:00 (p = 0.01 and p = 0.03, respectively). Young patients (age < 45 years) had two seizure occurrence peaks, 08:01–12:00 (p = 0.016) and 16:01–20:00 (p = 0.004). Middle-aged/old patients (≥ 45 years) had only one seizure occurrence peak, 08:01–12:00 (p = 0.012). Young patients had more seizures than middle-aged/old patients between 16:01–20:00 (p = 0.04). No differences were noted between left and right MTS.SignificanceWe observed two seizure occurrence peaks: morning and late afternoon/evening. We encountered variations in daytime and nighttime seizure distribution according to gender and age, but not according to side of MTS. Future studies are needed to confirm these findings and to unravel the neurobiological substrate underlying daytime and nighttime variations of seizure occurrence in different age groups and between genders.