Electroencephalographic (EEG) investigations in medulloblastomas

Electroencephalographic investigations were done in 24 patients suffering from medulloblastoma. All underwent subtotal or total removal of the tumour and a shunt procedure, foowed by irradiation therapy. The most frequent pre-operative finding was general slowing, the degree of which could be correlated to the amount of papilloedema and obstructive hydrocepalus. In about one third of the patients we found abnormal rhythmic theta and delta activities, especially marked in the occipital regions. This could be explained by the pathogenesis of hydrocephalus in the child. In the acute post-operative stage in some cases only the general slowing was worse. A return to normal of the EEG disturbances was seen in the later post-operative course and after irradiation therapy. This return to normal seemed to depend only on the time factor, but not on the mode of treatment.