Hemorrhagic subdural effusion complicating an endoscopic III ventriculostomy

Subdural effusion, a common postoperative complication of extracranial shunting for hydrocephalus, is usually caused by excessive drainage of cerebrospinal fluid. Subdural effusion is thought to occur less frequently after a neuroendoscopic III ventriculostomy, and no reported cases have been symptomatic. We encountered a symptomatic subdural effusion with a component of hemorrhage 5 days after the latter procedure was performed to treat massive hydrocephalus in a 2-year-old boy.