Second time around: Corticospinal responses following repeated sports-related concussions within the same season. A transcranial magnetic stimulation study

Abstract Objective To investigate the degree of neurophysiological and cognitive performance changes resulting from repeat concussions sustained in a single season of Australian Rules football. Methods Three amateur football players were recruited after sustainingtwo concussions during a single season of playing. Each player was assessed at multiple time points by transcranial magnetic stimulation (TMS) and electromyography, as well as tested for fine motor and cognitive performance after each concussion. Results In all three cases, concussions resulted in reduction in fine dexterity and visuomotor reaction time, cognitive attention performance and increase in intracortical inhibition from TMS. No changes in performance or TMS outcomes were found as a result of the order of the concussions. However, changes observed were dependent on the severity of the concussion. Conclusions This multiple-case study has demonstrated that concussion result in increased intracortical inhibition and reduction in cognitive and motor performance. Further, TMS, in conjunction with tests of cognitive and motor performance, can be useful as a prognostic technique in assessing recovery from acute concussion injury.