Delayed pneumocephalus following shunting for hydrocephalus.

Delayed pneumocephalus is a rare but well-reported complication of cerebrospinal fluid diversion procedures. In most cases the air enters the intracranial cavity via a skull base defect. We report a case of hydrocephalus secondary to aqueduct stenosis. The patient developed pneumocephalus 2 months after successful placement of a ventriculoperitoneal shunt. We describe an attempt at endoscopic diagnosis and repair of the fistula. This was unsuccessful, presumably because the defect was too small to localize even with the use of intrathecal fluorescein. We subsequently performed a conventional craniotomy and anterior fossa repair with placement of an antisiphon device. We suggest that in certain cases, when patients present with long-standing hydrocephalus, it may be advisable to insert either a high-pressure valve or antisiphon device as a primary measure.