Cerebral blood flow predicts recovery in children with persistent post-concussion symptoms following 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 (mean age 14 (SD=2.6) years; 41% male) with PPCS were imaged with 3D pseudo-continuous arterial spin-labelled (pCASL) MRI at 4-6 and 8-10 weeks post-injury. Exclusion criteria included any significant past medical history and/or previous concussion within three months. 23 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%CI: 43.32, 44.67) compared to those with good recovery, 42.19 (95%CI: 41.77, 42.60) ml/min/100g grey tissue and decreased over time (Beta=-1.75; p<.001). The decrease was greater in those with good recovery (Beta=2.29; p<.001) and predicted outcome in 77% of children with PPCS (OR .54, 95%CI: .36, .80; p=.002). Future studies are warranted to validate the utility of CBF as a useful predictive biomarker of outcome in PPCS.