Pneumocephalus and tension pneumocephalus after posterior fossa surgery in the sitting position: a prospective study.

Thirty patients subjected to posterior fossa surgery in the sitting position were evaluated postoperatively by CT scans in order to assess the true incidence of pneumocephalus and subsequent development, if any, of tension pneumocephalus. This prospective survey shows that the postoperative incidence of intracranial air was 100%, while no progression towards tension pneumocephalus producing severe neurological deterioration was observed. It can thus be claimed that, although the sitting position may favour the development of tension pneumocephalus also other factors contribute to its pathogenesis. Finally, neither nitrous oxide nor temperature play any significant role in the development of this complication.