Extra-axial

Dr Henry Knipe and A.Prof Frank Gaillard et al.

Extra-axial is a descriptive term to denote lesions that are external to the brain parenchyma, in contrast to intra-axial which describes lesions within the brain substance. 

Radiographic features

Often it is trivially easy to distinguish an intra-axial from an extra-axial mass. In many cases, especially when the mass is large and associated with parenchymal changes, such as oedema, localisation can be more difficult. A number of features are helpful in suggesting that a mass or lesion is extra-axial, including: 

Examples

Examples (non-exhaustive) of extra-axial lesions include:

See also
Share article

Article information

rID: 7961
Section: Gamuts
Synonyms or Alternate Spellings:
  • Extraaxial

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Case 1: subarachnoid haemorrhage (SAH)
    Drag here to reorder.
  • Drag
    T1 with Gad
    Case 2: haemangiopericytoma
    Drag here to reorder.
  • Drag
    CT
    Case 3: extradural haemorrhage (EDH)
    Drag here to reorder.
  • Drag
    Case 4: arachnoid cyst
    Drag here to reorder.
  • Drag
    Case 5: subdural haemorrhage (SDH)
    Drag here to reorder.
  • Drag
    Case 6: all three types of extra-axial haemorrhage
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.