Medical Discovery News
By Norbert Herzog and David Niesel
The hit was a hard one, leaving Cody, a high-school football player, with severe headaches for three days. After a CT scan of his brain came back normal, his doctor still recommended he not return to the football field until well after his symptoms had resolved.
But being committed to the sport and his team, he returned to practice. There he sustained another head injury that led to a condition known as second impact syndrome, and it was devastating. Six years later at age 23, Cody uses a wheelchair and has diminished mental capacity. Yet his parents consider him lucky since second impact syndrome is fatal in about 85 percent of cases.
When an athlete sustains a concussion and then sustains a second head injury, even a relatively mild one, it can result in diffuse cerebral swelling, brain herniation and even death. It is very rare, but seemingly healthy young athletes can die in a few minutes. The athlete dies before he or she can be stabilized or transported from the playing field to an emergency room.
A concussion is defined as an immediate and transient loss of consciousness accompanied by a short period of amnesia after a blow to the head. Post-concussive syndrome is diagnosed within four weeks if someone has symptoms, such as headache, dizziness, fatigue, insomnia, irritability, alcohol intolerance and difficulties with concentrating, memory, or intellectual processing. The severity of symptoms depends on the magnitude of the concussion. Minor concussions can resolve in a few days, while complex ones can last 10 days or more and may include additional symptoms like seizures, exertional headaches, cognitive impairment and confusion.
The cause of these symptoms after an initial concussion is cerebral edema or swelling of the brain. The brain tries to compensate by reducing blood flow, which alters the metabolism in the brain. This can last 10 days. All these changes make the brain more vulnerable to a second injury because it may not be able to auto-regulate the pressure in the brain. In severe cases, the immediate swelling of the brain can lead to its herniation, which is the reason second impact syndrome is lethal so quickly. It has also been shown that children experience greater brain swelling than adults in response to minor head trauma.
Those involved in sports at all levels have become much more aware of the risks of concussions. Athletes still showing even mild signs of concussion should not be allowed to return to the game. Unfortunately, the limited amount of available data has led to differences in opinion about when it is safe for an athlete to return to normal activities. The American Academy of Neurology has published guidelines that are often followed and other resources on itsWeb site.
Second impact syndrome is fortunately rare, but further study is needed to understand why it occurs in only some athletes after the second head injury. Athletes, coaches and parents need to be educated about short-term and long-term consequences of concussions and should not take chances with an athlete’s health.
Professors Norbert Herzog and David Niesel are biomedical scientists at the University of Texas Medical Branch. Learn more at medicaldiscoverynews.com.