August 24, 2015
A healthy 22-year-old individual with no history of alcoholism, in a coma after a road traffic accident
Diffuse Axonal Injury
- Background:
- Diffuse axonal injury (DAI) or shearing injury is an indirect brain injury that affects primarily the white matter.
- Sudden angular rotation of the head appears the most likely underlying mechanism.
- Clinical Features:
- Classically, patients with DAI present with low GCS starting at the moment of impact.
- Key Diagnostic Features:
- DAI is characterized by usually (80%) nonhemorrhagic white matter lesions mostly sparing the overlying cortex.
- The areas most commonly involved in DAI are the subcortical white matter, corpus callosum (especially splenium), corona radiata, internal capsule, and the dorsolateral aspect of the upper brainstem.
- FLAIR and DWI are the most useful imaging sequences for nonhemorrhagic DAI, whereas T2*-weighted sequences and SWI are more sensitive for hemorrhagic DAI.
- DDx:
- Cerebral fat embolism
- Usually there is an associated long bone fracture and a 24–72 hour latency period (rather than immediate) before decreased GCS.
- Typically associatied with respiratory distress and skin petechiae.
- DWI will show diffuse punctuate hyperintense foci called a "starfield pattern".
- Cerebral fat embolism
- Rx: Supportive measures, standard neuroprotection. Prognosis is poor if there is involvement of the brainstem.
