Concussion is defined as a closed-head injury (that is, one that does not involve a skull fracture) usually caused by blunt-force impact. Concussion was traditionally used by doctors to refer to temporary loss of consciousness from a head injury, but in everyday language, the term usually means any minor injury to the head or brain. Concussions
generally are not life-threatening but may involve long-term as well as short-term health problems.
Concussion occurs when the brain is pushed against one side of the skull, often by impact with a blunt object. The impact can result from aperson's striking the head against an object as well as being hit by something or someone. Athletic injuries are the most common cause of concussions, but concussions can also result from automobile, bicycle, or other transportation accidents, criminal assaults, workplace accidents, or accidents in the home—particularly falls.
Concussions are probably underreported because many mild cases resolve on their own and because many athletes do not want to miss scheduled competitions. One estimate is that there are six cases of concussion per 1,000 people per year in the United States, but this figure is probably too low.
Among children between the ages of five and fourteen, the most common causes of concussions are sports and bicycle accidents; among adults, the most common causes are falls and auto accidents. Soldiers in combat may have rates of concussion from bomb blasts as high as 15 percent.
The sports that place participants at the highest risk of a concussion are boxing, football, ice hockey, wrestling, rugby, and soccer. At the high school level, girls are more likely to be injured than boys (in sports played by both sexes) because of their smaller head and neck structure. According to the American College of Sports Medicine, studies of high school athletes show that the rate of concussions per 1,000 games is as follows: 0.59 for football; 0.25 for wrestling; 0.18 for boys' soccer and 0.23 for girls' soccer; 0.09 for girls' field hockey; and 0.11 for boys' basketball and 0.16 for girls' basketball.
The basic cause of a concussion is the rotation of the brain inside the skull as well as compression of the brain tissue against the sides of the skull when a person receives a blow on the head. Although the brain is cushioned against minor bumps by cerebrospinal fluid (CSF), the
amount of fluid between the brain and the skull is not enough to absorb the force of a heavy blow.
Doctors do not agree as to whether concussion is a disturbance of brain function only or whether it involves damage to the structure of the brain as well. It is presently thought that the forces from a blow to the head disrupt the normal activity of the cells in the brain tissue, and that it is this disruption that causes temporary alterations in consciousness.
The brain's secretion of neurotransmitters (the chemicals that convey signals from one nerve cell to another), its oxygen supply, and its use of glucose (blood sugar) are all affected by concussion. In addition, a small number of cells in the brain tissue may die as a result of even temporary interruptions of blood flow to the parts of the brain affected by the concussion.
The symptoms of a concussion include emotional and well as cognitive and physical symptoms:
- Physical symptoms: Headache (the most common symptom of concussion), dizziness, loss of balance or coordination, nausea and vomiting, visual disturbances, ringing in the ears, seizures or convulsions.
- Cognitive: Temporary loss or alteration of consciousness, difficulty concentrating, memory loss, confusion, disorientation, difficulty thinking clearly, disturbed sleep patterns.
- Emotional: Moodiness, tearfulness, temper outbursts, emotions inappropriate to a specific situation (such as laughing at a funeral), long-term personality changes.
It is possible for a person to suffer a mild concussion without knowing it, particularly if their attention was focused on something else—such as getting out of a damaged car, helping someone else to safety, or escaping from an attacker. They may not seek medical help afterward. Most people, however, will go to the doctor after a head injury if they have briefly lost consciousness, are having prolonged vomiting spells, severe headaches, or such vision problems as seeing double or seeing bright lights.
Concussions in Professional Sports
Several deaths among high-profile professional athletes focused attention on the dangers of ignoring or minimizing concussions—particularly the long-term effects of repeated head injuries. In 2006, Andre Waters, a professional football player, committed suicide in his Florida home. Waters's suicide was preceded in 2004 by the death of Justin Strzelczyk, another football star, in an auto accident following a 37-mile-long high-speed police chase on the wrong side of the highway.
Christopher Nowinski, a former professional wrestler whose career was ended by post-concussion syndrome in 2003, decided to investigate the effects of repeated concussions on professional athletes. Nowinski contacted a neurosurgeon at the University of Pittsburgh who was able to obtain samples of the dead football players' brain tissues after contacting their families. The doctor found that Waters's brain resembled that of an 85-year-old man with Alzheimer disease, and that Strzelczyk's personality changes in the weeks preceding his death could be traced to brain damage from repeated concussions. In 2007 Nowinski founded the Sports Legacy Institute, an organization dedicated to researching sports-related brain injuries in order to protect the health and lives of all athletes.
Because of the potential seriousness of a closed-head injury, the doctor will take a careful history of the injury (its cause and other details of the incident, as well as how long the patient was unconscious) as well
as a general medical history. The doctor will particularly need to know whether the patient has had previous head injuries; is taking any blood-thinning medications; or has a bleeding disorder. The history is followed by several examinations and imaging studies:
- General physical examination. The doctor looks for injuries to the head and neck, including bleeding from the ears or nose, or other indications that the skull may have been fractured.
- Neurological examination. This part of the examination involves testing the patient's reflexes, vision, hearing, balance, and coordination.
- A computed tomography (CT) scan. This type of imaging study is not always ordered if the concussion seems to have been mild. It is, however, usually performed if the patient is a child or elderly; is under the influence of alcohol or drugs; was injured in a motor vehicle accident; fell from a height of more than 3 feet (0.9 meters); cannot recall the accident or blow thirty minutes after it occurred; is having seizures; is vomiting; or is having trouble with short-term memory.
- Observation overnight in the hospital or at home for twenty-four to forty-eight hours. This is done to make sure that the patient does not have a more severe injury than was first thought. The doctor may ask a friend or relative of a patient sent home to wake them every few hours for the first thirty-six hours after the injury to make sure that they can return to full consciousness.
- Magnetic resonance imaging (MRI). This type of imaging study may be performed if the patient's headaches and other symptoms are getting worse or have lasted a week or longer.
Treatment of mild concussion usually consists of a mild over-the-counter pain reliever such as acetaminophen (Tylenol) or ibuprofen (Advil) plus bed rest and extra fluids. Aspirin should be avoided because it increases the risk of bleeding. If the patient has a bruise under the skin of the head (a “goose egg”), ice wrapped in a washcloth can be applied to relieve the swelling. Cuts in the skin may be treated in the doctor's office with a local anesthetic and stitches if necessary.
People injured in an athletic competition should not play again for at least seven to ten days after the concussion.
Prognosis depends on the severity of the concussion. Most people heal completely in one to two weeks, although healing may be somewhat slower in adults over fifty-five. About 10 percent of patients develop what is known as post-concussion syndrome (PCS). This is a condition marked by persistent headaches for two weeks to several months after the concussion. The patient may also have nausea and vomiting, or difficulty reading or concentrating on their work. PCS usually goes away on its own. If it persists after a few months, the patient will usually be referred to a neurologist for further evaluation.
The effects of concussions tend to add up over time; it is known, for example, that each concussion a person sustains makes it easier for them to suffer another concussion in the future. Repeated concussions can lead to permanent loss of memory and depression or other psychiatric disorders. Professional athletes are particularly likely to suffer long-term injuries from repeated concussions; several studies have found that the rate of depression is three times higher and the risk of Alzheimer disease five times higher in athletes who have had three or more concussions.
Not all accidents or other causes of concussions can be prevented. People can, however, lower their risk of concussions by taking the following safety measures:
- Sports: Athletes should wear protective headgear for such sports as martial arts, football, baseball, bicycling, motorcycling, roller-blading, and skateboarding. They should make sure their helmets and other protective gear are properly fitted. Coaches should insist that players are taught the rules of safe play and that they follow them. Last, players should report all head injuries to the team doctor even if they seem minor at the time.
- Workplace: People in occupations requiring hardhats should wear them at all times, particularly in construction work. Even a small object dropped from the upper floors of a building can cause a serious head injury.
- Home safety: Elderly persons or parents of small children should check their house or apartment for loose rugs, poor lighting, slippery floors, and other problems that increase the risk of falls—which are a common cause of concussions.
Concussions are likely to continue to be relatively commonplace head injuries, particularly in victims of bicycle, motorcycle, and auto accidents. Stricter regulations about allowing injured athletes to play, however, may reduce the rate of concussions and their long-term consequences in amateur as well as professional sports.
SEE ALSO Alzheimer disease; Depression; Shaken baby syndrome
WORDS TO KNOW
Closed-head injury : A head injury that does not involve fracturing of the skull.
Cognitive : Related to thinking, memory, and other conscious intellectual activities or processes.
Post-concussion syndrome (PCS) : A condition characterized by several weeks or months of headache following a head injury.
Judd, Sandra J. Sports Injuries Sourcebook, 3rd ed. Detroit, MI: Omnigraphics, 2007.
Solomon, Gary S., Karen M. Johnston, and Mark R. Lovell. The Heads-Up on Sport Concussion. Champaign, IL: Human Kinetics, 2006.
Centers for Disease Control and Prevention (CDC). Heads Up. Available online at http://www.cdc.gov/ncipc/tbi/CGToolKit/CTK_Video_WM_BB.htm (accessed June 2, 2008). This is an 11-minute video about the dangers of concussions in high school and professional sports. It is part of a CDC tool kit for high school athletic coaches, available at http://www.cdc.gov/ncipc/tbi/Coaches_Tool_Kit.htm.
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National Center for Injury Prevention and Control (NCIPC). Facts about Concussion and Brain Injury. Available online in PDF format at http://www.cdc.gov/ncipc/tbi/tbibook.pdf and in interactive Flash movie format at http://www.cdc.gov/ncipc/tbi/Brain3.html (updated September 2006; accessed June 2, 2008).
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