Treatment of a symptomatic posterior fossa subdural effusion in a child.

We describe the first observation of a child with a posterior fossa subdural effusion with secondary hydrocephalus and tonsillar herniation. We diagnosed this entity in a 14-month-old girl with no history of trauma or coagulation disorder. The patient presented in our emergency department with opisthotonus and raised intracranial pressure resulting from supratentorial hydrocephalus. An emergency ventriculo-peritoneal shunt was placed, which resolved the symptoms only temporarily. Eventually external drainage of the subdural fluid was performed. The collection gradually disappeared, and both the external subdural shunt and the ventriculo-peritoneal shunt were removed. The patient made a complete neurological recovery. We review the physiopathology and treatment of subdural effusions in general, and propose some guidelines for the management of symptomatic effusions occurring in the posterior fossa in particular.