Second Impact Syndrome (SIS) is a serious brain condition that can occur when a second concussion is suffered before the effects of a previous concussion have healed. With SIS, acute and often fatal brain swelling occurs; because the onset of swelling is rapid, it may be impossible to control.
The risk of SIS is higher in boxing, football, baseball, basketball, soccer, hockey, and snow skiing than in other sports or activities.
A lack of awareness on the part of parents and coaches puts many student athletes at increased risk of developing SIS. Although there may not be any danger in returning to the field following a knee or shoulder injury, a child or teen who shows even mild symptoms of brain injury should be sidelined until a doctor who is trained in concussion management confirms that it is safe to return to the sport.
SIS can occur even if the second head injury was relatively mild and occurred days or weeks after the first.
Although Second Impact Syndrome does not occur frequently, it is devastating for those who are affected. Victims of the condition who don’t die are left with long-term brain injuries. According to NBC News, every reported case of SIS has occurred in a young person, most likely due to the fact that a youthful developing brain has less room to accommodate swelling.