Pneumocephalus arises when there is a breach in the integrity of the cranial bone or dura and a pressure gradient that allows air to enter the cranial cavity. It is a relatively common occurrence after skull base surgery, and in the majority of cases the air resolves spontaneously. Cases that persist or progress can become life-threatening and may require surgical intervention to alleviate the pressure.
The first case of pneumocephalus (cranial aerocele) was reported by Lecat in 1741.1 In 1884, Chiari diagnosed pneumocephalus in a postmortem examination of a subject with ethmoiditis, and demonstrated a fistulous connection between the ethmoid cavity and the frontal lobe of the brain.2 In 1913, Luckett3 provided the first radiographic evidence of intracranial air in a living person. Since then, pneumocephalus has been described in a wide variety of clinical settings,4 typically after head trauma or postsurgical procedures. In a review by Markham5 of 295 patients with pneumocephalus, trauma was the etiological factor in 73.9% of cases, followed by tumor (12.9%), infection (8.8%), surgical intervention (3.7%), and unknown causes (0.6%). Andrews and Canalis6 reviewed 54 cases involving patients with pneumocephalus of otologic origin. Thirty-six percent of the cases resulted from trauma; the others were due to otitis media (30%), otologic surgery (30%), and congenital defects (2%).
Imaging Quiz Case 1. Arch Otolaryngol Head Neck Surg. 2000;126(12):1499-1503. doi: