Traumatic Axonal Injury on Early Magnetic Resonance Imaging and Associations with Long-Term Outcome in Children with Moderate and Severe Traumatic Brain Injury

In a cohort of children and adolescents with moderate and severe traumatic brain injury (TBI), we explored the location and burden of traumatic axonal injury (TAI) on early magnetic resonance imaging (MRI) and its associations with long-term outcomes at 1 and 5 years post-injury. Fifty-six patients (0-18 years) with moderate (n = 29) or severe (n = 27) TBI, where MRI was performed within 6 weeks, were prospectively included. TAI lesion locations (including grading), numbers, and volumes were registered on fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging, and locations and numbers were registered on T2* gradient echo or susceptibility-weighted imaging. Long-term outcomes at 1 and 5 years post-injury were dichotomized into good outcome (Glasgow Outcome Scale Extended GOSE score 7-8) and disability (GOSE score ≤6). Logistic regression analyses, unadjusted and adjusted for the presence of TAI on the different MRI sequences, were performed. The median age was 14.3 years, 66% were boys, and the median number of days to MRI was 8. TAI was found in 89% of the patients with severe TBI and 72% of the patients with moderate TBI. The volumes of TAI on FLAIR were larger in the severe group than in the moderate group (p = 0.007). We found an increased risk of disability at 1-year post-injury with both more severe standard TAI grades (p = 0.005) and Trondheim TAI-MRI grades (p = 0.001). Similar results were found at 5 years post-injury. TAI bilaterally in the basal ganglia, thalami, mesencephalon, and/or pons was only observed in patients with severe TBI and disability. TAI had a high prevalence in our moderate-to-severe pediatric TBI cohort, and more severe grades of TAI were associated with an increased risk of disability at both 1 and 5 years post-injury. Assessing TAI on early MRI in pediatric TBI patients provides valuable prognostic insights and supports the optimization of rehabilitation strategies.