The epileptiform significance of intermittent rhythmic delta activity in childhood.

Intermittent rhythmic delta activity is reported in various disorders and is classified as a nonspecific abnormal electroencephalographic pattern. We have investigated its clinical and electroencephalographic features in childhood. Intermittent rhythmic delta activity was identified in 54 children over a period of 48 months. Epilepsy was present in 81%, 4% had only a single generalized tonic-clonic seizure, and 15% had no seizures. Generalized seizures were more common than partial seizures (83% versus 13%; 4% were mixed). The largest group of patients had idiopathic epilepsy. Epileptiform features were present in 70%. No patient identified prospectively has had a space-occupying lesion. Intermittent rhythmic delta activity should be considered an epileptiform pattern in children, most commonly occurring as an interictal pattern in primary generalized epilepsy.