Tension pneumocephalus following surgical evacuation of chronic subdural hematoma.

A case among 23 consecutive cases of chronic subdural hematoma developed tension pneumocephalus following surgical evacuation via a burr hole under local anesthesia. A closed drainage system applied into the subdural space was considered to be responsible for its formation as a result of one-way valve mechanism. In all 23 cases, preoperative and postoperative CT scans were reviewed in order to evaluate clinical significance of air in the subdural space after surgery. Air was noticed in all cases with various amount. However, unless the mass effect by air was more than the mass effect by chronic subdural hematoma, it was not necessary to remove air regardless of its amount.