Electroencephalographic findings in hydrocephalic children prior to initial shunting.

The EEG recordings of 105 hydrocephalic children with proven ventriculomegaly and increased intracranial pressure were studied prior to initial shunt treatment. Only 2 patients had a normal EEG and 7 had only abnormal dominant activity. Paroxysmal slow-wave activity, generalized or posterior, was present in 37 (35% of the patients) recordings and focal slow waves in 28 patients (27%), these mostly posterior. All types of slow-wave activities increased with age. Focal attenuation was very common under 1 year of age (in 41% of patients of this age group), but after this age only 4 cases (10%) were recorded. Spike- or sharp-wave activity was recorded focally or generally in 45 (43%) of the children. The prevalence of spikes and sharp waves correlated negatively with increasing age: only generalized spikes were usual after 7 years of age. No significant differences were found in the appearance of focal findings between hemispheres. According to the present study, the EEG is abnormal in more than 98% of children with proven hydrocephalus before shunting. The observed abnormalities are described in detail in order to serve as reference material in the follow-up of hydrocephalic children.