Mount Fuji sign

Mount Fuji sign is seen on cross-sectional imaging and is indicative of a tension pneumocephalus

The sign refers to the presence of gas (pneumocephalus) between the tips of the frontal lobes with a heaped-up appearance giving the silhouette-like appearance of Mount Fuji 1-3. It suggests that the pressure of the gas is at least greater than that of the surface tension of cerebrospinal fluid between the frontal lobes 1-3.  

The appearance of this sign often warrants immediate surgery to prevent permanent neurological damage. However, conservative management in patients with no signs of raised intracranial pressure has also been described 4.

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Article information

rID: 12518
Section: Signs
Synonyms or Alternate Spellings:
  • Mt Fuji sign
  • Mt. Fuji sign

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Cases and figures

  • Figure 1: Mount Fuji (Japan)
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