Concussion is a trauma-induced change in mental status, with confusion and amnesia, and with or without a brief loss of consciousness.
A concussion occurs when the head hits or is hit by an object, or when the brain is jarred against the skull with sufficient force to cause temporary loss of function in the higher centers of the brain. The injured person may remain conscious or lose consciousness briefly and is disoriented for some minutes after the blow.
According to the Centers for Disease Control and Prevention, approximately 300,000 people sustain mild to moderate sports-related brain injuries each year, most of them young men between 16 and 25 years of age.
The risk of concussion from football is extremely high, especially at the high school level. Studies show that approximately one in five players suffer concussion or more serious brain injury during their brief high-school careers. The rate at the collegiate level is approximately one in 20. Rates for hockey players are not known as certainly but are believed to be similar.
Causes and symptoms
Most concussions are caused by motor vehicle accidents and sports injuries . In motor vehicle accidents, concussion can occur without an actual blow to the head. Instead, concussion occurs because the skull suddenly decelerates or stops, which causes the brain to be jarred against the skull. Contact sports , especially football, hockey, and boxing, are among those most likely to lead to concussion. Other significant causes include falls, collisions, or blows due to bicycling, horseback riding, skiing, and soccer.
Concussion and lasting brain damage is an especially significant risk for boxers, since the goal of the sport is, in fact, to deliver a concussion to the opponent. For this reason, the American Academy of Neurology has called for a ban on boxing. Repeated concussions over months or years can cause cumulative head injury . The cumulative brain injuries suffered by most boxers can lead to permanent brain damage. Multiple blows to the head can cause punch-drunk syndrome or dementia pugilistica, as evidenced by Muhammad Ali, whose Parkinson's is a result of his career in the ring.
Young children are likely to suffer concussions from falls or collisions on the playground or around the home. Child abuse is, unfortunately, another common cause of concussion.
Symptoms of concussion include the following:
- disorientation as to time, date, or place
- vacant stare or confused expression
- incoherent or incomprehensible speech
- lack of coordination or weakness
- amnesia for the events immediately preceding the blow
- nausea or vomiting
- double vision
- ringing in the ears
These symptoms may last from several minutes to several hours. More severe or longer-lasting symptoms may indicate more severe brain injury. The person with a concussion may or may not lose consciousness from the blow; if he does lose consciousness, it will be for several minutes at the most. Prolonged unconsciousness indicates more severe brain injury.
The severity of concussion is graded on a three-point scale, used as a basis for treatment decisions.
- Grade 1: no loss of consciousness, transient confusion, and other symptoms that resolve within 15 minutes
- Grade 2: no loss of consciousness, transient confusion, and other symptoms that require more than 15 minutes to resolve
- Grade 3: loss of consciousness for any period
Days or weeks after the accident, the person may show signs of the following:
- poor attention and concentration
- memory difficulties
- sleep disturbances
- light and noise intolerance
The occurrence of such symptoms is called "post-concussion syndrome."
When to call the doctor
A doctor should be consulted whenever a head injury causes any of the symptoms noted above.
It is very important for those attending an individual with a concussion to pay close attention to the person's symptoms and progression immediately after the accident. The duration of unconsciousness and degree of confusion are very important indicators of the severity of the injury and help guide the diagnostic process and treatment decisions.
A doctor, nurse, or emergency medical technician may make an immediate assessment based on the severity of the symptoms; a neurologic exam of the pupils, coordination, and sensation, and brief tests of orientation, memory, and concentration. Those with very mild concussions may not need to be hospitalized or have expensive diagnostic tests. Questionable or more severe cases may require computed tomography scan (CT) or magnetic resonance imaging (MRI) scans to look for brain injury.
The symptoms of concussion usually clear quickly and without lasting effect, if no further injury is sustained during the healing process. Guidelines for returning to sports activities are based on the severity of the concussion.
A grade 1 concussion can usually be treated with rest and continued observation alone. The person may return to sports activities that same day, but only after examination by a trained professional, and after all symptoms have completely resolved. If the person sustains a second concussion of any severity that same day, he or she should not be allowed to continue contact sports until he or she has been symptom-free, during both rest and activity, for one week.
A person with a grade 2 concussion must discontinue sports activity for the day, should be evaluated by a trained professional, and should be observed closely throughout the day to make sure that all symptoms have completely cleared. Worsening of symptoms or continuation of any symptoms beyond one week indicates the need for a CT or MRI scan. Return to contact sports should only occur after one week with no symptoms, both at rest and during activity, and following examination by a physician. Following a second grade 2 concussion, the person should remain symptom-free for two weeks before resuming contact sports.
A person with a grade 3 concussion (involving any loss of consciousness, no matter how brief) should be examined by a medical professional either on the scene or in an emergency room. More severe symptoms may warrant a CT or MRI scan, along with a thorough neurological and physical exam. The person should be hospitalized if any abnormalities are found or if confusion persists. Prolonged unconsciousness and worsening symptoms require urgent neurosurgical evaluation or transfer to a trauma center. Following discharge from professional care, the person is closely monitored for neurological symptoms that may arise or worsen. If headaches or other symptoms worsen or last longer than one week, a CT or MRI scan should be performed. Contact sports are avoided for one week following unconsciousness of only seconds, and for two weeks for unconsciousness of a minute or more. A person receiving a second grade 3 concussion should avoid contact sports for at least a month after all symptoms have cleared and then engage in the sport only with the approval of a physician. If signs of brain swelling or bleeding are seen on a CT or MRI scan, the athlete should not return to the sport for the rest of the season, or even indefinitely.
For someone who has sustained a concussion of any severity, it is critically important that he or she avoid the possibility of another blow to the head until well after all symptoms have cleared to prevent second-impact syndrome. The guidelines above are designed to minimize the risk of this syndrome.
Concussion usually leaves no lasting neurological problems. Nonetheless, symptoms of post-concussion syndrome may last for weeks or even months.
Studies of concussion in contact sports have shown that the risk of sustaining a second concussion is even greater than it was for the first if the person continues to engage in the sport.
While concussion usually resolves on its own without lasting effect, it can set the stage for a much more serious condition. Second impact syndrome occurs when a person with a concussion, even a very mild one, suffers a second blow before fully recovering from the first. The brain swelling and increased intracranial pressure can lead to a potentially fatal result. More than 20 such cases have been reported since the syndrome was first described in 1984.
Many cases of concussion can be prevented by using appropriate protective equipment. This includes seat belts and air bags in automobiles and helmets in all contact sports. Helmets should also be worn while bicycling, skiing, or horseback riding. Soccer players should avoid heading the ball when it is kicked at high velocity from close range. The surfaces immediately below and surrounding playground equipment should be covered with soft material, either sand or special matting.
The value of high-contact sports such as boxing, football, or hockey should be weighed against the high risk of brain injury during a young person's participation in the sport. Steering a child's general enthusiasm for sports into activities less apt to produce head impacts may reduce the likelihood of brain injury. Children participating in any contact sport or activity that can cause brain injury should always wear a helmet.
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American Academy of Emergency Medicine. 611 East Wells Street, Milwaukee, WI 53202. Web site: http://www.aaem.org/.
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211–2672. Web site: http://www.aafp.org/.
American Academy of Neurology. 1080 Montreal Avenue, St. Paul, MN 55116. Web site: http://www.aan.com/.
American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: http://www.aap.org/default.htm.
American College of Emergency Physicians. PO Box 619911, Dallas, TX 75261–9911. Web site: http://www.acep.org/.
Brain Injury Association. 105 North Alfred Street, Alexandria, VA 22314. Web site: http://www.biausa.org/Sportsfs.htm.
International Brain Injury Association. 1150 South Washington Street, Suite 210, Alexandria, VA 22314. Web site: http://www.internationalbrain.org/.
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L. Fleming Fallon, Jr., MD, DrPH
Amnesia —A general medical term for loss of memory that is not due to ordinary forgetfulness. Amnesia can be caused by head injuries, brain disease, or epilepsy, as well as by dissociation. Includes: 1) Anterograde amnesia: inability to retain the memory of events occurring after the time of the injury or disease which brought about the amnesic state. 2) Retrograde amnesia: inability to recall the memory of events which occurred prior to the time of the injury or disease which brought about the amnesic state.
Parkinson's disease —A slowly progressive disease that destroys nerve cells in the basal ganglia and thus causes loss of dopamine, a chemical that aids in transmission of nerve signals (neurotransmitter). Parkinson's is characterized by shaking in resting muscles, a stooping posture, slurred speech, muscular stiffness, and weakness.