Neuroradiological Manifestations of Focal Polymorphic Delta Activity in Children

To examine the neuroradiological and clinical correlations of focal continuous polymorphic delta activity (PDA) in children, we reviewed the records of patients with continuous PDA that was either focal or lateralized to one hemisphere. Of 2571 electroencephalograms (EEGs) performed between July 1, 1988, and December 31, 1990, a total of 125 records from 87 patients revealed continuous PDA. Eighty of these patients had neuroimaging performed either by computed tomographic scan (n = 59) or by magnetic resonance imaging (n = 38) within 8 weeks of the EEG. Twenty-two patients (28%) showed no abnormalities on neuroimaging, 16 patients (20%) showed diffuse abnormalities, and 42 patients (52%) showed focal abnormalities that correlated with the EEG findings. Most (18 of 22) patients with no neuroradiological abnormalities presented to the hospital with seizures from various causes. The presence of focal spikes or additional focal EEG abnormalities did not differ significantly among the three imaging groups. Generalized EEG abnormalities and multifocal spikes were significantly more common among the patients who had generalized abnormalities on neuroimaging. Focal continuous PDA without correlated changes on neuroimaging occurred in 48% of patients, which is much higher than what has been reported in adults.