Diffuse axonal injury (DAI) in moderate to severe head injured patients: Pure DAI vs. non-pure DAI

Diffuse axonal injury (DAI) is known to be associated with poor outcome. DAI often associates with other intracranial injuries but their distinct features have not been established. In this retrospective cohort study, we compared clinical outcomes between pure and non-pure DAI patients.

Total of 1047 traumatic brain injury (TBI) patients visited our institute between 2011 and 2017. Age ranged between 15-85 years old and Glasgow coma scale (GCS) score less than 13 were included. DAI was diagnosed in 45 patients using CT and MRI and their clinical features and outcomes were compared depending on their associated cranial injury; 20 patients without evidence of associated injury (Pure DAI group) and other 25 patients with associated injury (Non-pure DAI group). DAI stage was adopted using Gentry, L.R.

Glasgow outcome scale (GOS) was measured at least 6 months after trauma to evaluate their functional outcome.

The mean age and follow-up period were 45.36 years and 15.09 months, respectively. There were no significant differences between pure and non-pure DAI groups regarding demographic data and clinical findings on their admission. Logistic regression model was used to examine the association between GOS and clinical factors. In this analysis, pure DAI was no significantly different to non-pure DAI (p = 0.607). However, DAI Stage, transfusion, and hypotension on admission were strongly related to poor outcome. Stage III showed sevenfold higher risk when compared to Stage I (p = 0.010). The risk was also high when Stage III was compare to Stage I and II (p = 0.002). Interestingly, no significant difference was observed between Stage I and II (p = 0.847).

Unfavorable outcome was observed in 14 patients (31.11%) which was lower than we expected. Interestingly, non-pure DAI was no worse than pure DAI on their functional outcome. However, DAI Stage III was independently associated with poor outcome when compared to Stage I or I and II. Finally, we concluded that Stage II is clinically more related to Stage I, rather than Stage III.