Clinical correlates of frontal intermittent rhythmic delta activity in children

Frontal intermittent rhythmic delta activity is an electrographic pattern of unclear origin. Previously thought to correlate with deep midline and infratentorial pathology, rather, it appears to be associated with encephalopathy states in adults. The significance of frontal intermittent rhythmic delta activity in children has not been studied. We analyzed the electrographic characteristics and clinical associations of pediatric frontal intermittent rhythmic delta activity. This pattern was rarely detected, occurring in 20 of 1500 electroencephalographic (EEG) studies. Patients' ages ranged between 1.5 and 17 years. Most patients were awake and showed no signs of acute encephalopathy when frontal intermittent rhythmic delta activity occurred. Half of the children were cognitively impaired, and half had a history of epilepsy. Epileptiform activity was present in 55% of the EEG recordings. However, frontal intermittent rhythmic delta activity was part of the epileptiform discharge in only a minority of cases. The duration of frontal intermittent rhythmic delta activity bursts was longer in the mentally retarded group. Most patients did not have structural brain pathology. None had deep midline or infratentorial lesions. In conclusion, frontal intermittent rhythmic delta activity is rare in children, is not associated with acute encephalopathy or with deep midline or infratentorial lesions, and tends to occur during wakefulness. The electrographic characteristics of frontal intermittent rhythmic delta activity appear to differ between cognitively normal and mentally retarded children.