Nocturnal epileptiform EEG discharges, nocturnal epileptic seizures, and language impairments in children: review of the literature

This review addresses the effect on language function of nocturnal epileptiform EEG discharges and nocturnal epileptic seizures in children. In clinical practice, language impairment is frequently reported in association with nocturnal epileptiform activity. Vice versa, nocturnal epileptiform EEG abnormalities are a common finding in children with specific language impairment. We suggest a spectrum that is characterized by nocturnal epileptiform activity and language impairment ranging from specific language impairment to rolandic epilepsy, nocturnal frontal lobe epilepsy, electrical status epilepticus of sleep, and Landau-Kleffner syndrome. In this spectrum, children with specific language impairment have the best outcome, and children with electrical status epilepticus of sleep or Landau-Kleffner syndrome, the worst. The exact nature of this relationship and the factors causing this spectrum are unknown. We suggest that nocturnal epileptiform EEG discharges and nocturnal epileptic seizures during development will cause or contribute to diseased neuronal networks involving language. The diseased neuronal networks are less efficient compared with normal neuronal networks. This disorganization may cause language impairments.