Occluded fourth ventricle (trapped ventricle) is reported in eight of 47 children (17%) receiving repeated shunt revisions for hydrocephalus at the Stritch School of Medicine, Loyola University of Chicago, Maywood, IL. The hydrocephalus was caused by intraventricular hemorrhage but the fourth ventricular enlargement developed only after shunting. Massive dilatation of the ventricle occurred in four, three developed a progressive spastic quadriparesis, and two had increased intracranial pressure with lethargy and vomiting. Two children underwent a fourth ventricular shunt; one became more alert and less quadriparetic, and the other showed gradual improvement in motor function. 
COMMENT. Trapped ventricle following repeated shunting may be manifested by headache, lethargy, vomiting, ataxia, spastic quadriparesis, cranial nerve palsies and head tilt. This complication appears to be common among children with intraventricular hemorrhage who have received ventricular peritoneal shunting. Progressive fourth ventricular enlargement may be silent and diagnosis requires post shunt neural imaging and brain stem auditory evoked responses. Shunting of the fourth ventricle results in clinical improvement.