Second Impact Syndrome

July 12, 2013

By Medical Discovery News

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 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 they can be stabilized or transported from the playing field to an ER.

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 abilities. 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. This is why children should wear helmets.

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 their Web site. 

Second impact syndrome is fortunately rare, but further study is needed to understand why it occurs to only some athletes after the second head injury. Athletes, coaches, and parents need to be educated about the short-term and long-term consequences of concussions and should not take chances with the athlete’s health.

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Gene for the Gold

By Medical Discovery News

Dec. 22, 2012


By the time the last athlete received their medal at the London Olympics, a record number of competitors underwent testing for performance enhancers. The International Olympic Committee took over 6,000 blood and urine samples to screen for performance enhancers that an athlete could use to boost athletic abilities. Despite this massive effort to keep the competition fair, the committee already predicts even greater efforts in future games as it contends with athletes who risk trying a way to boost performance: gene doping.

Though no athlete has been found guilty of gene manipulation yet, the idea that certain power genes could enhance athletic prowess no doubt presents a strong temptation. Currently, gene therapy is undergoing testing in people with inherited disorders such as muscular dystrophy and sickle cell anemia. Ambitious and unscrupulous athletes could use the same technology to gain a competitive advantage.

The temptation is bolstered by mounting evidence that certain elite athletes naturally possess these genes. Naturally occurring variations of over 200 genes have been identified as important to athletic success. One gene variant carried by Finnish cross-country skier Eero Mäntyranta is the erythropoietin receptor gene EPOR, which causes him to produce extra red blood cells, boosting his oxygen-carrying capacity by 25 to 50 percent. This probably helped him earn his seven Olympic cross-country ski medals.

Another, the I variant of the ACE gene found in 94 percent of the Sherpa in Nepal and in elite British long distance runners, is associated with increased endurance. However, the gene by itself, working in isolation, may not guarantee any improved athletic performance. For example, about half of Eurasians and 85 percent of Africans carry at least one copy of this endurance gene variant.

Athleticism is not likely associated with just one particular form of a gene, but results from a combination of traits that provide a natural advantage. Becoming an elite athlete requires extraordinary dedication, hard work, and professional training.

As gene therapy to treat medical conditions gains momentum and results, the sporting world might be suspicious of patients treated with this therapy. If someone undergoes gene therapy using a variant like the EPOR gene to cure familial erythrocytosis type 1, they could be ineligible to compete in the Olympics if the committee bans gene manipulation altogether.

Neither gene therapy nor gene doping are ready for prime time, but that is unlikely to stop an unscrupulous person from offering these services or an unethical athlete from trying them.  Given the fame and money that come with athletic greatness, gene doping will inevitably become an issue in future Olympic Games and other athletic events. As sport governing bodies develop tests to identify gene doping, they will have to consider how to differentiate between naturally gifted athletes and those deliberately modifying their genes.

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