Tension pneumocephalus following evacuation of chronic subdural haematoma.

Five cases of a rare complication of tension pneumocephalus following evacuation of chronic subdural haematoma are described. This occurred in 8% of all cases of chronic subdural haematoma treated following installation of a CT scanner. The chronically compressed brain contributes to the ingress of this intracranial air. The increase in the brain bulk and gradual re-expansion of the brain, in the early postoperative period, competes with the trapped subdural air resulting in a rise in intracranial pressure leading to neurological deterioration. Twist drill craniostomy and aspiration, using a brain cannula with a three-way connector, has produced excellent results.