Progressive tension pneumocephalus as a delayed postoperative complication in the absence of any obvious CSF leak.

Tension pneumocephalus is a rare neurosurgical emergency usually causing rapid deterioration. Slowly-progressive postoperative tension pneumocephalus is very rare. We present a case that came to our attention 5 weeks after a craniotomy with gradual development of symptoms, and in the absence of any obvious CSF leak. A dural defect causing a one-way valve system was found at explorative craniotomy.