Spontaneous pneumocephalus secondary to a cerebrospinal fluid fistula demonstrated by CT cisternography.

We report a case of a middle-aged woman who presented to our emergency department with increasing headache in a nontraumatic setting. The presence of intracranial air was an unexpected finding on nonenhanced computed tomography (CT). CT and magnetic resonance imaging could not identify the origin of the bone defect responsible for pneumocephalus. CT cisternography was able to demonstrate the presence of a cerebrospinal fluid fistula resulting in pneumocephalus. This case highlights the role of CT cisternography to identify and localize small osseous defects and cerebrospinal fluid fistulas when CT and magnetic resonance imaging findings are normal.