Second Impact Syndrome

When a person suffers a second concussion before symptoms from an earlier concussion have subsided, the brain swells rapidly shortly thereafter. This is rare condition, but when it does happen, it is most often fatal. The few who do not die from such an event are usually left severely disabled for life. This is called the Second Impact Syndrome (SIS).

It is a devastating event because young, otherwise healthy patients can die within a few minutes of suffering the second concussion. Death or lifelong disability occurs because the brain suddenly loses its ability to regulate cerebral spinal fluid pressure, leading to severe swelling of the brain and possible herniation of the brain.

The impact of the second event does not have to be strong to trigger second impact syndrome. A minor blow to the head, chest or back that snaps the head enough to cause the brain to move inside the skull can trigger the usually lethal damage.

When a concussion patient whose symptoms have not yet resolved sustains a second impact, they may not even lose consciousness at the moment of the impact, but they may look stunned. They may even complete a game and make it to the sideline themselves, but then collapse within a minute or two. The patient’s condition then deterioreates rapidly with loss of consciousness, loss of eye movement, dilated pupils, then respiratory failure. This can all take place within a few minutes.

Obviously the most sensible approach to avoid a Second Impact Syndrome from occuring is to prevent the first concussion from happening, and then take enough time for the (first) concussion to heal. Any concussed patient who still shows signs of concussion should not be allowed in any activities where another impact is possible.

Signs and symptoms of Second Impact Syndrome include fatigue, headache, disorientation, nausea, vomiting, feeling “in a fog” or “slowed down,” as well as other difference from the patient’s normal behaviour and function.