Clinical and imaging assessment of acute combat mild traumatic brain injury in Afghanistan

Objective: To evaluate whether diffusion tensor imaging (DTI) will noninvasively reveal white matter changes not present on conventional MRI in acute blast-related mild traumatic brain injury (mTBI) and to determine correlations with clinical measures and recovery. Methods: Prospective observational study of 95 US military service members with mTBI enrolled within 7 days from injury in Afghanistan and 101 healthy controls. Assessments included Rivermead Post-Concussion Symptoms Questionnaire (RPCSQ), Post-Traumatic Stress Disorder Checklist Military (PCLM), Beck Depression Inventory (BDI), Balance Error Scoring System (BESS), Automated Neuropsychological Assessment Metrics (ANAM), conventional MRI, and DTI. Results: Significantly greater impairment was observed in participants with mTBI vs controls: RPCSQ (19.7 +/- 12.9 vs 3.6 +/- 7.1, p < 0.001), PCLM (32 +/- 13.2 vs 20.9 +/- 7.1, p < 0.001), BDI (7.4 +/- 6.8 vs 2.5 +/- 4.9, p < 0.001), and BESS (18.2 +/- 8.4 vs 15.1 +/- 8.3, p = 0.01). The largest effect size in ANAM performance decline was in simple reaction time (mTBI 74.5 +/- 148.4 vs control -11 +/- 46.6 milliseconds, p < 0.001). Fractional anisotropy was significantly reduced in mTBI compared with controls in the right superior longitudinal fasciculus (0.393 +/- 0.022 vs 0.405 +/- 0.023, p < 0.001). No abnormalities were detected with conventional MRI. Time to return to duty correlated with RPCSQ (r = 0.53, p < 0.001), ANAM simple reaction time decline (r = 0.49, p < 0.0001), PCLM (r = 0.47, p < 0.0001), and BDI (r = 0.36 p = 0.0005). Conclusions: Somatic, behavioral, and cognitive symptoms and performance deficits are substantially elevated in acute blast-related mTBI. Postconcussive symptoms and performance on measures of posttraumatic stress disorder, depression, and neurocognitive performance at initial presentation correlate with return-to-duty time. Although changes in fractional anisotropy are uncommon and subtle, DTI is more sensitive than conventional MRI in imaging white matter integrity in blast-related mTBI acutely.