An unusual cause of acute headache: subarachnoid free air secondary to spontaneous bronchopleurodurosubarachnoid fistula from a Pancoast tumor.

Pneumocephalus and pneumorrhachis are related to transgression of the barriers to the central nervous system. We present a patient with a Pancoast tumor treated with palliative chemoradiation who developed symptomatic spinal and intracranial air caused by spontaneous bronchopleurodurosubarachnoid fistula secondary to direct tumor invasion into the thecal sac.