Neurophysiological anomalies in symptomatic and asymptomatic concussed athletes.

OBJECTIVE: Concussion in sports is a problem of such magnitude that improvements in diagnosis and management are desirable. The aim of the present study was to investigate the effect of concussion on event-related potentials, in symptomatic as well as in asymptomatic athletes.
METHODS: Twenty symptomatic and asymptomatic athletes who sustained a concussion were compared with 10 control athletes in a modified auditory Oddball task. The task included a sequence of tones containing standard and deviant stimuli. Participants were asked to respond to the target tone presented in the left ear and to ignore tones presented in the right ear. The electroencephalogram was recorded from 28 electrodes during the task.
RESULTS: The results showed a reduction in the amplitude of N1, P2, and P3 components in symptomatic and asymptomatic athletes in comparison with control athletes. No between-group differences were observed in reaction times or in latency of the event-related potentials components, except for P3 latency, in which the controls showed shorter latency than the concussed groups.
CONCLUSION: Concussions seem to produce deficits in the early and late stages of auditory information processing, which possibly reflect impaired brain functioning in symptomatic and asymptomatic concussed athletes. The fact that asymptomatic athletes have an electrophysiological profile similar to that of symptomatic athletes challenges the validity of return-to-play guidelines for which the absence of symptoms is a major issue.