Association between frequency of nocturnal epilepsy and language disturbance in children.

In clinical practice, an association is commonly suggested between nocturnal epileptiform activity and language disorders in children. However, this association has not been studied systematically. This study explored the correlation between daily and nocturnal epileptiform discharges ratio, frequency of nocturnal epileptiform discharges, and severity of nocturnal seizures in correlation with the severity of language impairment. A total of 326 children referred to an epilepsy center were included. All children had a 24-hour electroencephalogram (EEG), a neuropsychologic assessment, and a reconfirmed diagnosis of epilepsy. The balance between verbal and performance IQ scores of the Wechsler Intelligence Scale for Children was a focus of the study. A significant correlation between the severity of nocturnal seizures and lower verbal IQ scores compared to performance IQ scores was found (P < 0.05). There was a clinically relevant difference between performance IQ and verbal IQ between the groups of children with only nocturnal epileptiform EEG discharges and only epileptiform EEG discharges during wake (P = 0.033). Children with nocturnal epileptiform EEG discharges have lower verbal than performance IQs when compared to children with only epileptiform EEG discharges during wake. Although a causal relationship is unclear, this indicates an association between the occurrence of nocturnal epileptiform EEG discharges and language disturbance.