The Mount Fuji Sign

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     A 53-year-old woman was admitted because of progressive right-sided hemiparesis and aphasia. A computed tomographic (CT) scan of the brain revealed a space-occupying supratentorial lesion. A biopsy through a burr hole led to the histologic diagnosis of primary B-cell lymphoma of the central nervous system. Systemic treatment with corticosteroids and methotrexate was initiated, resulting in clinical stabilization. Six weeks later, the patient became disoriented and lethargic. A second CT scan of the brain showed a massive accumulation of air that was compressing the frontal lobes, a condition called the Mount Fuji sign. Dark-to-black areas in the frontal region were caused by intracranial air outside of the brain. The burr hole was surgically revised, and a pin-sized leak was found to have caused the tension pneumocephalus.

    Severe pneumocephalus can occur after neurosurgical procedures, after percutaneous irradiation, after trauma with leakage of cerebrospinal fluid, or even spontaneously. Although small amounts of air are usually reabsorbed without complications, the phenomenon of tension pneumocephalus, with increasing air entrapment, can lead to serious clinical deterioration. The typical CT finding resembles the silhouette of a volcano, such as Mount Fuji. A "peaking" sign is also indicative of increased tension and occurs when the frontal lobes form a peak in the midline on account of intact bridging veins.

    Josef G. Heckmann, M.D.

    Oliver Ganslandt, M.D.

    University Hospital Erlangen

    91054 Erlangen, Germany

    http://www.100md.com/html/DirDu/2006/11/29/30/50/10.htm