Clinical and electroencephalographic correlation of independent multifocal spike discharges.

One hundred and eight patients with independent, multifocal, spike discharges in the EEG were studied. The abnormality occurred at all ages but was more frequent between 4 and 7 years. The basic EEG activity in wake tracing was invariably slow for the age of the patient. The majority of the patients with independent multifocal spike discharges had extensive bilateral cerebral lesions that occurred in the prenatal, perinatal, or postnatal periods. Clinical seizures were of different types, and patients had varying degrees of intellectural and neurologic deficits. A significant number had had previous tracings with either hypsarrhythmic or slow spike-wave patterns, suggesting a close relationship of these three EEG abnormalities.