Severe Intracranial Hypotension After a Middle Fossa Approach for Spontaneous Otogenic Pneumocephalus

Abstract

Spontaneous otogenic pneumocephalus is a rare condition caused by erosion of the tegmen tympani with subsequent entrance of air into the intracranial space. Its pathogenesis is thought to involve a previous state of intracranial hypotension, which pulls air into the intracranial cavity. The surgical management involves obliteration of the tegmen defect via a mastoidectomy or a middle fossa approach. Lumbar drainage has been used safely as an adjunct to middle fossa approaches so as to provide brain relaxation and decrease the incidence of postoperative cerebrospinal fluid leaks. A 66-year-old male patient with otogenic pneumocephalus caused by nose blowing underwent repair of a tegmen tympani defect through a middle fossa approach, with the aid of intraoperative lumbar drainage. Progressive neurologic deterioration was seen postoperatively with obtundation and anisocoria. Computed tomography scans of the head demonstrated marked midline shift and transtentorial herniation. Recumbency and blood patch failed to improve the neurological condition. Intrathecal infusion of normal saline enabled clinical and radiological improvement. Intraoperative lumbar drainage during a middle fossa approach for spontaneous otogenic pneumocephalus may dramatically aggravate a state of preexisting intracranial hypotension and lead to transtentorial herniation.