Diffuse axonal injury (grading)

Dr Andrew Dixon et al.

Grading of diffuse axonal injury has been described histologically according to the anatomic distribution of injury, which correlated with outcome 1-3. The classification was first proposed by Adams in 1989 4 and divides diffuse axonal injury (DAI) into three grades:

  • grade I: involves grey-white matter interfaces
    • most commonly: parasagittal regions of frontal lobes, periventricular temporal lobes
    • less commonly: parietal and occipital lobes, internal and external capsules, and cerebellum
    • often inapparent on conventional imaging
    • may have changes on MR spectroscopy (MRS) 3
  • grade II: involves corpus callosum in addition to grade I locations
    • observed in approximately 20% of patients
    • most commonly: posterior body and splenium but does advance anteriorly with increasing severity of injury
    • most frequently unilateral
    • may be seen on SWI 3
  • grade III: involves brainstem in addition to grade I and II locations
    • most commonly: rostral midbrain, superior cerebellar peduncles, medial lemnisci and corticospinal tracts

A 2017 study has suggested that the Adam's grade on MRI does not correlate well with neurological outcome, and that age above 30 years and DAI involvement of the substantia nigra and tegmentum of the midbrain are probably the most important predictors of poor neurological recovery 5

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Article information

rID: 10020
Tag: trauma
Synonyms or Alternate Spellings:
  • Diffuse axonal injury (DAI) grading
  • Diffuse axonal injury grading
  • DAI grading

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Cases and figures

  • Case 1: grade II (GRE)
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  • Case 2: grade III (FLAIR): brainstem
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  • Case 3: grade III (T2)
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