Postoperative brain stem tension pneumocephalus causing transient locked-in syndrome.

The incidence of pneumocephalus after supratentorial craniotomy has been reported to be as high as 100%. However, transformation of postoperative pneumocephalus into tension pneumocephalus (symptomatic intracranial air) is a rather rare phenomenon. Tension pneumocephalus after posterior fossa surgery is reported mainly when the surgery is performed in a sitting position. We hereby report on a patient who developed brain-stem tension pneumocephalus in the early postoperative period after posterior fossa craniotomy for an exophytic brainstem astrocytoma, operated in the prone position. A complete locked-in syndrome resolved following surgical relief of the trapped air.