Tension pneumocephalus associated with rupture of a middle fossa encephalocele. Case report.

Acquired nontraumatic (spontaneous) encephaloceles of the middle fossa are not common. Rupture of an encephalocele frequently leads to a cerebrospinal fluid fistula. Tension pneumocephalus consequent to rupture of an encephalocele has not been previously reported, but conceivably occurs by means of a ball-valve mechanism in the ensuing fistulous tract. An unusual case is presented of an elderly man who suffered acute life-threatening neurological symptoms from a tension pneumocephalus that likely developed from rupture of an acquired nontraumatic encephalocele of the left middle fossa. The symptoms correlated with the location of the intracranial abnormalities. The literature is reviewed and the pathophysiology of the lesion is discussed.