Subacute sclerosing panencephalitis: atypical absence attacks as first symptom.

Subacute sclerosing panencephalitis was diagnosed in a 10-year-old girl who had suffered from atypical absence attacks for 3 months; diagnosis was made after 5 months of these attacks. Characteristic EEG findings included diffuse spike and wave complexes of about 2.5 Hz associated with desynchronization during the absence attacks, and recruiting rhythm during the tonic seizure. As the lesion responsible for these EEG patterns originated in the brainstem, subcortical structures were probably affected early in the disease. The SSPE complexes may have originated chiefly in the brainstem since, in this case, they were recognized even during the period of absence attacks.