Second Impact Syndrome

We all love a good game, especially a good ol' fashioned high school football game. But it's becoming clear that kids who play sports face a very real risk of brain injury, which for them is more damaging than adults who suffer the same trauma. Children are more likely than adults to have brain swelling even after a minor head trauma — and here is a surprising new finding.

A person with a head injury can actually have a normal CT scan, but then die if soon after they're hit with a second head impact. Though rare, this condition is called Second Impact Syndrome or SIS.

The study looked at a 17 year old football player named Cody who took a hard hit leaving him with a severe headache for three days. Though he had a normal CT scan, his doctor told him not to play. He did anyway and collapsed during practice after repeated hits caused SIS. Six years later Cody uses a wheelchair and has diminished mental capacity.

Yet he is fortunate because 85% of SIS cases are fatal. This time, Cody's CT scan showed brain swelling, bleeding, and brain herniation, when swelling forces parts of the brain to shift. He had kidney failure, cardiac arrest, and was barely responsive.

In SIS, there is a massive increase of blood flow to the brain because it loses the ability to autoregulate. When the brain is initially injured, it reduces blood flow coming in to compensate for the swelling. But that safeguard can fail if the brain is impacted again before it recovers.

Doctors are still learning why certain young athletes are more vulnerable to second impact syndrome. For now, they warn that athletes whose head injury causes severe and persistent headaches may be at risk for SIS and should not play.