Do minor head impacts in soccer cause concussive injury? A prospective case-control study.
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.


CONCLUSIONS
A reduced neuropsychological performance was found after minor head impacts in soccer, even in allegedly asymptomatic players. However, the long-term cognitive consequences are uncertain.
Department of Sports Medicine, Oslo Sports Trauma Research Center, Norwegian School of Sports Sciences, Oslo, Norway. truls.straume-nesheim@nih.no
Truls M
TM
Straume-Naesheim
Thor Einar
TE
Andersen
Ingar Morten
IM
K Holme
Andrew S
AS
McIntosh
Jiri
J
Dvorak
Roald
R
Bahr
D000062:Accidents, Occupational / Q000706:statistics & numerical data; D000328:Adult; D001265:Athletic Injuries / Q000150:complications*; D001315:Australia; D001924:Brain Concussion / Q000453:epidemiology* / Q000209:etiology*; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000209:etiology; D015331:Cohort Studies; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012916:Soccer