Hyrtl’s fissure

Hyrtl's fissure (also known as tympanomeningeal fissure) is a congenital infralabyrinthic fissure. It is a very rare cause of spontaneous CSF ottorhoea and meningitis.


This fissure is present in the developing fetal petrous temporal bone and is typically ossified by 24 weeks.

Radiographic features

  • this can be diagnosed on axial slices and coronal reformations
  • CT cisternography and radionuclide cisternography can diagnose this rare condition
  • heavily T2 weighted images are helpful


Once the diagnosis is established, attempts to surgically close the fissure can be planned.

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Article information

rID: 25517
Synonyms or Alternate Spellings:
  • Hyrtl’s fissures
  • Hyrtl fissure

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