Tension pneumocephalus in association with ventriculoperitoneal shunt.

The authors report a case of tension pneumocephalus in association with a ventriculoperitoneal shunt for obstructive hydrocephalus, due to the presence of a pineal tumour. In this unique form of tension pneumocephalus, air from the middle ear must have penetrated into the brain parenchyma and later on into the ventricular system through pre-existing congenital defects in the bony tegmen tympani and the covering dura mater. The possible pathogenetic mechanisms of this kind of tension pneumocephalus are discussed.