CT scans of patients with a tension pneumocephalus typically show air that compresses the frontal lobes of the brain, which results in a tented appearance of the brain in the skull known as the Mount Fuji sign.

[1][2][3] The name is derived from the resemblance of the brain to Mount Fuji in Japan, a volcano known for its symmetrical cone.

In typical cases, there is a symmetrical depression near the midline (such as the crater of a volcano), due to intact bridging veins.

[5] Pneumocephalus has also been shown to follow neurosurgical procedures such as deep brain stimulation and hematoma evacuation (e.g., chronic subdural hematoma[6]), where while seemingly innocuous to the patient, may cause brain shift, subsequent stereotactic inaccuracy, and even another surgical intervention.

[9] Efforts are made by neurosurgeons to reduce pneumocephalus volume during surgery, and thus, subsequent brain shift.