Examining Microstructural White Matter Differences between Children with Typical and Those with Delayed Recovery Two Weeks Post-Concussion

Delayed recovery from concussion can dramatically affect a child's social, emotional, and educational development, yet little is known about what causes some children to recover faster than others. The contribution of white matter disruption in children with delayed recovery has been hypothesized, but findings are limited by methodological issues such as: small heterogeneous samples, bias toward children with delayed recovery, and inconsistencies in timing of brain imaging, both within and between studies. The aim of the present study was to assess diffusion neuroimaging correlates of delayed recovery post-concussion in children. A prospective, longitudinal, observational cohort study was conducted at a statewide tertiary pediatric hospital. Forty-three children who presented to the emergency department (ED) with concussion (defined according to the Zurich/Berlin Consensus Statement on Concussion in Sport) underwent magnetic resonance imaging (MRI) at a 2 weeks post-injury and were classified as either normally recovering (n = 26) or delayed recovering (n = 17). Diffusion imaging comparison using voxelwise tract-based spatial statistics (TBSS) analysis found no difference between the groups in fractional anisotropy, axial diffusion, radial diffusion, or mean diffusivity metrics (p > 0.05 threshold-free cluster enhancement [TFCE] corrected). Post-hoc tract-based Bayesian analysis found evidence for the null in 11 unique white matter tracts (Bayes factor >3). These findings indicate that delayed recovery from post-concussive symptoms in children is unlikely to be caused by white matter microstructural damage.