Hair on end sign (mnemonic)

The hair on end sign refers to a radiographic appearance of the diploic space of the skull vault which results from a thickening of trabeculae as the diploic space expands. These trabeculae are perpendicular in orientation, interspersed by radiolucent marrow hyperplasia along with skull vault.

It is classically described with plain skull radiographs although can also be appreciated on CT or MRI 3. Causes include:

A useful mnemonic to remember the various causes of this sign is:

  • HI NEST 4

Mnemonic

Article information

rID: 9384
Section: Signs, Mnemonics
Synonyms or Alternate Spellings:
  • HI NEST (mnemonic)
  • Hair on end appearances (mnemonic)
  • Hair-on-end sign (mnemonic)
  • Hair on end appearance (mnemonic)

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Cases and figures

  • Case 1
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  • Case 2: in thalassemia
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  • Case 3
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  • Case 4
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  • Case 5: on MRI
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  • Case 6: thalassemia major on CT
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