EEG topography in porencephaly and arachnoid cyst.

With the topographic EEG mapping method, the correlation between the morphologic abnormality of the brain and its functional changes was investigated in 13 patients with porencephaly and arachnoid cyst verified by CT scan. The spatial distribution of the EEG activity was displayed in the delta, theta, alpha-1, alpha-2, beta-1, and beta-2 frequency bands. The abnormality of EEG topographic images (e.g., an increase of the power of delta activity and/or a decrease of the power of alpha activity in the involved side of the brain) was more marked in cases with porencephaly than those with arachnoid cyst, and in cases with mental retardation or paralysis than among those without.