Mount Fuji Sign
Last edit by Alaric Steinmetz on
The Mount Fuji sign is a radiological sign caused by a bilateral intracranial accumulation of air and is indicative of tension pneumocephalus.
Nomenclature
The name Mount Fuji sign is derived from Japan's Mount Fuji, as it resembles the CT image.
Pathophysiology
The Mount Fuji sign is caused by an intracranial accumulation of air. This may be iatrogenic or non-iatrogenic. During a supine CT examination, the air rises anteriorly, resulting in compression of the frontal lobe and the typical Mount Fuji sign on CT imaging. Typically, a valve mechanism is necessary, allowing air to enter the intracranial space without being able to escape, in order to generate sufficiently high pressure to cause compression of the frontal lobe.
Etiology
One possible cause of the bilateral accumulation of air may be an intracranial procedure, such as burr-hole trephination following evacuation of a chronic subdural hematoma, in which an incorrectly placed drain creates a valve mechanism, allowing air to enter the intracranial space without being able to escape.
Imaging
The Mount Fuji sign is classically diagnosed on CT imaging, but it can also be diagnosed on MRI.
References
