An estimated 300,000 sports related traumatic brain injuries, TBIs, of mild to moderate severity , most of which can be classified as concussions, (i.e., conditions of temporary altered mental status as a result of head trauma, occur in the United States each year.  The proportion of these concussions that are repeat injuries is unknown; however, there is an increased risk for subsequent TBI among persons who have had at least one previous TBI .  Repeated mild brain injuries occurring over an extended period (i.e., months or years can result in cumulative neurologic and cognitive deficits, but repeated mild brain injuries occurring within a short period (i.e., hours, days, weeks) can be catastrophic or fatal.  The latter phenomenon, termed "second impact syndrome" has been reported more frequently since it was first characterized in 1984.  This page describes two cases of second impact syndrome and presents recommendations developed by the American Academy of Neurology to prevent recurrent brain injuries in sports and their adverse consequences.

Case Reports:

     Case 1.  During October 1991, a 17-year-old high school football player was tackled on the last day of the first half of a varsity game and struck his head on the ground.  During half-time intermission, he told a teammate that he felt ill and had a headache; he did not tell his coach.  He played again during the third quarter and received several routine blows to his helmet during blocks and tackles.  He then collapsed on the field and was taken to a local hospital in a coma.  A computerized tomography (CT-Scan) brain scan revealed diffuse swelling of the brain and a small subdural hematoma.  He was transferred to a regional trauma center, where attempts to reduce elevated intracranial pressure were unsuccessful, and he was pronounced dead 4 days later.  Autopsy  revealed diffuse brain swelling focal areas of subcortical ischemia, and a small sub dural hematoma. TBI Glossary
 

     Case 2.  During August 1993, a 19-year-old college football player reported headache to family members after a full contact-practice during summer training.  During practice the following day he collapsed on the field approximately 2 minutes after engaging in a tackle.  He was transported to a nearby trauma center where a CT scan of the head showed diffuse brain swelling and a thin subdural hematoma.  Attempts to control the elevated intracranial pressure failed, and he was pronounced brain dead 3 days later.  Autopsy revealed the brain to be diffusely swollen with evidence of cerebrovascular congestion and features of temporal lobe herniation.
 

     Second Impact Syndrome.  The two cases described above involved repeated head trauma with probable concussions that separately might be considered mild but in additive effect were fatal.  The risk for catastrophic effects from successive seemingly mild concussions sustained within a short period is not yet widely recognized.  Second Impact Syndrome results from acute, usually fatal, brain swelling that occurs when a second concussion is sustained before complete recovery from a previous concussion that causes vascular congestion and increased intracranial pressure, which may be difficult or impossible to control.
 

     The Dangers of Concussion
    " ...during the minutes to few days after concussion injury, brain cells that are not irreversibly destroyed remain alive but exist in a vulnerable state. This concept of injury-induced vulnerability has been put forth to describe the fact that patients suffering from head injury are extremely vulnerable to the consequences of even minor changes in cerebral blood flow and/or increases in intracranial pressure and apnea....

     "Experimental studies have identified metabolic dysfunction as the key  postconcussion physiologic event that produces and maintains this state of vulnerability. This period of enhanced vulnerability is characterized by both an increase in the demand for glucose (fuel) and an inexplicable reduction in cerebral blood flow (fuel delivery).58 The result is an inability of the neurovascular system to respond to increasing demands for energy to reestablish its normal chemical and ionic environments. This is dangerous because these altered environments can kill brain cells." -- 
The American Orthopaedic Society for Sports Medicine - url: http://www.intelli.com/vhosts/aossm-isite/html/main.cgi?sub=151

     Relative Risk.  The risk for second impact syndrome should be considered in a variety of sports associated with likelihood of blows to the head, including boxing, football, ice or roller hockey, soccer, baseball, basketball, and snow skiing. 

    Neurologists say once a person suffers a concussion, he is as much as four times more likely to sustain a second one. Moreover, after several concussions, it takes less of a blow to cause the injury and requires more time to recover.  Troy Aikman sustained 8 concussions that he publicly admits to, the last two occurred since January 1, 2000.  According to league officials there are about 160 concussions in the N.F.L. and 70 in the NHL each year. 

Sideline Guidelines.  The American Academy of Neurology has adopted recommendations for the management of concussion in sports that are designed to prevent second impact syndrome and to reduce the frequency of other cumulative brain injuries related to sports.  These recommendations define symptoms and signs of concussion of varying severity and indicate intervals during which athletes should refrain from sports activity following a concussion.  Following head impact athletes with any alteration in mental status, including transient confusion or amnesia with or without loss of consciousness, should not return to activity until examined by a health -care provider familiar with these guidelines.

     The popularity of contact sports in the United States exposes a large number of participants to risk for brain injury.  Recurrent brain injuries can be serious or fatal and may not respond to medical treatment.  However, recurrent brain injuries and second impact syndrome are highly preventable.  Physicians, health and physical education instructors, athletic coaches and trainers parents of children participating in contact sports and the general public should become familiar with these recommendations.

Source:  Centers for Disease Control and Prevention, Dept. of Health and Human Services, USA. 1997 

Also see our Coma page

 The amount of force calculated the moment a soccer ball hits the head of a player is  208 joules. Since the jaw is not attached to the skull, and knowing that every force  produces equal and opposite directional components of force, the impact causes  the lower jaw to slam against the base of the skull. These forces account for a large  percentage of the damage found in the jaw joints of soccer players. 
WIPSS Products, Inc.- email: wwhitney@voicenet.com -- URL: http://www.wipss.com/

     This incident motivated his father to find head protection but he soon realized that no practical product existed. He was surprised to learn from a review of the scientific literature that there was a potential for long-term effects even from non-catastrophic head injuries (when the player does not lose consciousness). While concerned about his son's safety, he also knew that Charles wanted to continue to play the game he loved. This is what led him to co-found SoccerDocs. url: http://www.soccerdocs.com/
Telephones :1-877-HEADER-1 -- 1-877-432-3371 -- 612- 823-2426

     Dr. David Janda, director of the Institute for Preventative Sports Medicine, said he plans to test Zatlin's headband at his Ann Arbor, Mich., lab. But he expressed concern it would protect children only from the headers they do correctly, leaving the most tender spot at the top of the head exposed. 

       "When you watch kids learn to head the ball, they'll hit it off the front of their head, the back of their head, the side of the head, their shoulder -- they're all over the map," Janda said. "A headband type of approach still leaves the head vulnerable." telephone: 314- 652-2700 -- url: http://www.headblast.com/