Do minor head impacts in soccer cause concussive injury? : a prospective case-control study

Abstract

OBJECTIVE: Our objective was to determine whether minor head trauma in elite soccer matches causes measurable impairment in brain function. METHODS: Baseline neuropsychological testing was completed by professional soccer players in the Norwegian elite league, Tippeligaen, before the 2004 and 2005 seasons (n 462). A player who experienced a head impact during a league match completed a follow- up test the next day (head impact group). Videotapes of all impacts were collected and reviewed. A group of players without head impacts was also tested after a league match to serve as controls (matched control group; n 47). RESULTS: A total of 228 impacts were identified, and 44 (19.3%) of these were followed up with a CogSport test (CogState, Ltd., Charlton South, Australia; the players who were tested tended to have more severe injuries, but there were only 6 cases with loss of consciousness). The head impact group had a greater change in reaction time from baseline to follow- up compared with the matched control group with regard to the 3 simplest tasks. The largest deficits were seen among the players reporting acute symptoms after the impact, but deficits were also demonstrated among asymptomatic players. Players who experienced 1 or more head impacts during the 2004 season showed a reduction in neuropsychological performance when tested before the 2005 season. However, none of these players was impaired when compared with the test manufacturer’s normative data. CONCLUSION: A reduced neuropsychological performance was found after minor head impacts in soccer, even in allegedly asymptomatic players. However, the longterm cognitive consequences are uncertain.