Cerebral Blood Flow Predicts Recovery in Children with Persistent Post-Concussion Symptoms after Mild Traumatic Brain Injury.

Persistent post-concussion symptoms (PPCS) following pediatric mild traumatic brain injury (mTBI) are associated with differential changes in cerebral blood flow (CBF). Given its potential as a therapeutic target, we examined CBF changes during recovery in children with PPCS. We hypothesized that CBF would decrease and that such decreases would mirror clinical recovery. In a prospective cohort study, 61 children and adolescents (mean age 14 [standard deviation = 2.6] years; 41% male) with PPCS were imaged with three-dimensional (3D) pseudo-continuous arterial spin-labelled (pCASL) magnetic resonance imaging (MRI) at 4-6 and 8-10 weeks post-injury. Exclusion criteria included any significant past medical history and/or previous concussion within the past 3 months. Twenty-three participants had clinically recovered at the time of the second scan. We found that relative and mean absolute CBF were higher in participants with poor recovery, 44.0 (95% confidence interval [CI]: 43.32, 44.67) than in those with good recovery, 42.19 (95% CI: 41.77, 42.60) mL/min/100 g gray tissue and decreased over time (β = -1.75;  < 0.001). The decrease was greater in those with good recovery (β = 2.29;  < 0.001) and predicted outcome in 77% of children with PPCS (odds ratio [OR] 0.54, 95% CI: 0.36, 0.80;  = 0.002). Future studies are warranted to validate the utility of CBF as a useful predictive biomarker of outcome in PPCS.