SIS is a potential complication 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<unk><unk>  to cause SIS. Also, the<unk><unk>  may be very minor, even a blow such as an<unk>  to the chest that causes the head to jerk, thereby transmitting forces of acceleration to the brain. Loss of consciousness during the<unk>  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<unk>  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<unk><unk> , and death can follow shortly. SIS is sometimes associated with a small subdural hematoma.
Second-impact syndrome
Post-intensive care syndrome
Sandifer syndrome
Tumor lysis syndrome
Overlap syndrome
Majeed syndrome
Compartment syndrome
Edwards syndrome