Sensory integration processes characterize concussed athletes with balance deficits

Impaired postural control constitutes a major symptom after mild traumatic brain injuries (mTBI/sport-related concussions (SRC)). In order to uphold cognition and behavior during pathological situations, individuals may be characterized by neuronal upregulation. Because postural control necessitates the integration of sensory information within somatosensory (/parietal) cortices, we investigated the hypothesis that athletes with ongoing symptoms after SRC are characterized by increased brain activation within these areas in order to compensate for postural deficits. Sixty-six athletes (27 +/- 13 years; 50 men, 16 women) participated in the study. Twenty-two concussed athletes reported high post-concussion symptoms (PCS; symptomatic group), and 22 concussed athletes reported low PCS (asymptomatic group). Twenty-two healthy non-concussed athletes served as a control group. Postural control was assessed by a pressure distribution measuring plate during four balance conditions with eyes closed/open whilst either standing on a stable/unstable surface. Brain oxygenation was collected during postural control tasks by functional near-infrared spectroscopy (fNIRS) above pre- and postcentral cortices of both hemispheres. Increased postural sway was found in symptomatic athletes when compared to control athletes' overall conditions as well as during unstable surface conditions. Symptomatic athletes were characterized by increased brain activation within the parietal cortex overall balance conditions and when compared to asymptomatic athletes. Increased brain activation within somatosensory and parietal cortices during postural control indicates that sensory integration processes are upregulated in concussed athletes with persisting symptoms. However, such potentially compensatory processes seem to constitute an ineffective neuronal mechanism as affected athletes cannot countervail post-concussion balance deficits.