Recovery from mild head injury in sports: Evidence from serial functional magnetic resonance imaging studies in male athletes

Objective: To examine functional brain activation patterns before and after postconcussive symptoms (PCS) resolution. Design: Prospective serial study with male athletes using functional magnetic resonance imaging (fMRI). Setting: Hospital laboratory and imaging facility. Participants: 9 symptomatic concussed athletes who experienced persisting PCS at least I month postinjury and 6 healthy athletes. Interventions: All athletes filled out a PCS checklist and underwent an fMRI session during which they performed a working-memory task. Main outcome measurements: Behavioral outcomes were response speed and accuracy on the working memory tasks performed during the fMRI session. Functional imaging outcomes were blood oxygen level-dependent fMRI activation patterns associated with a working memory task. Results: There was no difference in behavioral performance between the groups. Despite normal structural MRI findings, all symptomatic concussed athletes initially showed atypical brain activation patterns in the dorsolateral prefrontal cortex (DLPC). Compared to the initial postinjury evaluation, those athletes at follow-up with PCS resolved showed significant increases in activation in the left DLPC. Concussed athletes whose PCS status remained unchanged at follow-up continued to show atypical activation in DLPC. Healthy athletes showed remarkably clear and consistent brain activations in DLPC initially as well as in follow-up, highlighting the test-retest reliability of fMRI. Conclusions: The results demonstrate the feasibility of using fMRI to detect an underlying pathology in symptomatic concussed athletes with normal structural imaging results and its potential to document recovery. Such information may be of considerable value for clinical judgment and patient management.