Complications after shunting isolated IV ventricles.

An isolated IV ventricle in chronically shunted patients is being reported with increasing frequency. Complications associated with posterior fossa shunting, however, have seldom been described. Between January 1986 and December 1995, we treated 292 children younger than 16 years for hydrocephalus: 7 (2.4%) developed an isolated IV ventricle, and 5 of these were symptomatic with posterior fossa signs. These 5 patients required posterior fossa shunting, after which their neurological status improved. However, 1 week and 6 weeks after surgery, respectively, 2 patients developed new cranial nerve deficits related to a slit-like IV ventricle with secondary irritation of the brain stem by the IV ventricular catheter. Shortening the catheter and replacing the valve eliminated the cranial nerve palsies, implying that these complications were not caused by direct injury of the brain stem during placement of the shunt. Alternative surgical techniques and the use of different (flow-regulating) valves may avoid such complications.