Features
SIS is the most serious potential complication that could result from an athlete returning to a game before symptoms from a minor head injury have subsided. Such symptoms include headache, cognitive difficulties, or visual changes.
The initial injury may be a concussion, or it may be another, more severe, type of head trauma, such as cerebral contusion. However, the first concussion need not be severe for the second impact to cause SIS. Also, the second impact may be very minor, even a blow such as an impact to the chest that causes the head to jerk, thereby transmitting forces of acceleration to the brain. Loss of consciousness during the second injury is not necessary for SIS to occur. Both injuries may take place in the same game.
The athlete may continue playing in the game after the second concussion, and may walk off the field without assistance, but symptoms quickly progress and the condition can rapidly worsen. Neurological collapse can occur within a short period, with rapid onset of dilating pupils, loss of eye movement, unconsciousness, and respiratory failure. Failure of the brain stem frequently occurs between two and five minutes after the second impact, and death can follow shortly.
SIS is sometimes associated with a small subdural hematoma.
Read more about this topic: Second-impact Syndrome
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