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Grading of diffuse axonal injury

Dr Yuranga Weerakkody and 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 1989⁴ 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 MRS ³
grade II : involves corpus callosum in addition to stage 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 stage I and II locations
- most commonly : rostral midbrain, superior cerebellar peduncles, medial lemnisci and corticospinal tracts