[Concussion and sport: too often underdiagnosed].

Concussions are frequent in contact sports. Clinical symptoms, cognitive impairment, neurobehavioral features can be present. Loss of consciousness is rare. If suspicion, the player must be removed from the game. Return to play is gradual; it may be possible only if the sportsman is asymptomatic. Strict application of the rules of the game, fair play can decrease the incidence of concussion. SCAT (pocket, SCAT 3, SCAT Child) should be used as a help to diagnosis and follow up.