Epileptic seizures and abnormal electroencephalographic findings in hydrocephalus and their relation to the shunting procedures.

A total of 92 patients with hydrocephalus were studied. The incidence of seizures was significantly greater in the "shunted" group (18.2% in the "non-shunted" and 65.4% in the "shunted" group). All of the shunted patients who had seizures developed them after the placement of the shunt. Left sided focal motor seizures were the commonest focal seizures in the patients with right sided shunts. There was a higher incidence of abnormal EEG tracings in the "shunt" group (47% of the "non-shunt" patients and 95% of the "shunt" group). All types of focal EEG abnormalities, but particularly the slow wave foci, were seen more frequently over the hemisphere which had the shunt, and in more than half these localized to the neighborhood of the shunt itself. It is suggested that the shunt, which may act as a foreign body, may be responsible, at least in part, for these findings.