concussion

More about Concussion: Causes and symptoms Diagnosis Treatment Prognosis Prevention Resources

Definition

Concussion is a trauma-induced change in mental status, with confusion and amnesia, and with or without a brief loss of consciousness.

Description

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.

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 that can result is potentially fatal. More than 20 such cases have been reported since the syndrome was first described in 1984.

— Richard Robinson

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n.

1. A violent jarring; a shock. See synonyms at collision.
2. An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.

[Middle English concussioun, bruise, contusion, from Latin concussiō, concussiōn-, concussion, from concussus, past participle of concutere, to strike together. See concuss.]

concussive con·cus'sive (-kŭs'ĭv) adj.
concussively con·cus'sive·ly adv.

For more information on concussion, visit Britannica.com.

A state following injury in which there is temporary functional impairment without physical evidence of damage to the impaired tissues. The term usually refers to cerebral concussion produced by any type of trauma.

From a clinical point of view cerebral concussion is produced by a head injury which causes temporary unconsciousness but with complete recovery within 24 h. This temporary alteration is believed to result from one of several mechanisms. In all of these a sudden acceleration or deceleration appears to be a prerequisite. The sudden movement is thought to cause an unequal shifting of tissues of different specific gravities within the skull, between skull and brain, or between different brain tissues. See also Brain.

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This word originally meant severe shaking, or the shock of an impact, but has come to mean the effect of such violence on the brain. The immediate effect of such an impact — usually when the moving head meets an immovable object, most commonly the ground — is unconsciousness. After a mild injury this lasts only a minute or so and the person is then dazed or confused for a few more minutes before recovering normal consciousness; occasionally recovery may take hours. After more severe impact injury, the patient may remain in coma for many days and remain confused for many more days thereafter. In either event there will be no memory for the moment of impact, often for a period immediately before this, and always for the period of unconsciousness and confusion: this is known as post-traumatic amnesia.

For many years ‘concussion’ was applied only to mild injuries, when it was assumed that the brief loss of consciousness was due to temporary chemical or electrical events resulting from the mechanical forces acting on the brain. It is now recognized that the effect of the jelly-like brain being distorted by these forces is to stretch or even tear delicate nerve fibres, resulting in some permanent damage. After mild injury this is very limited, but after more severe impact there is more severe and more widespread damage to fibres. There can therefore be both mild and severe concussion and it is misleading to ask ‘Was it only concussion?’

After only mild concussion there are often symptoms for several days, sometimes weeks — headache, fatigue, dizziness, and poor concentration. In a few patients these post-concussional symptoms give rise to anxiety and other psychological symptoms that can aggravate and prolong the organically-impaired function that the patient suffers. In contact sports there is the risk of repeated concussions, and the small amount of damage sustained each time can be cumulative. Moreover, soon after one concussion the brain may be more susceptible to a second blow, and this is why most sports have rules about waiting 2-3 weeks before playing again, for example after concussion on the football field or in the boxing ring. The repeated concussions over a period of years that boxers can experience may result in progressive brain damage, evident in altered mental function and control of the limbs — the so-called ‘punch-drunk’ syndrome. This is now rare, as there are stringent regulations to limit exposure to such a hazard.

— Bryan Jennett

See also boxing; coma.

knockout

A sudden, transient loss of consciousness due to a blow to the head. The blow produces mechanical acceleration and deceleration forces that act on the brain. This impairs mental function, and can cause confusion. Concussion may last a few minutes or a few hours and is often accompanied by pallor, slowness, feebleness of heartbeat, shallow breathing, and reduction in reflex responses.

Individuals suffering from concussion are usually advised to avoid body-contact activities for at least three weeks. In some sports, such as Rugby Union football, this lay-off period is mandatory. Boxers suffering from concussion after being knocked out in the ring may also be required to avoid boxing for a time. In Britain, amateur boxers are not allowed in the ring again until 28 days after the first knockout, 84 days after the second knockout, and 1 year after the third knockout. In the USA, many team physicians in contact sports follow the ‘1-2-3’ rule: one concussion and the player is removed from the game; two concussions results in the player missing the rest of the season; and after three concussions the player is advised to stop completely.

noun

Violent forcible contact between two or more things: bump, collision, crash, impact, jar, jolt, percussion, shock, smash. See conflict/cooperation.

Definition

Concussion is a trauma-induced change in mental status, with confusion and amnesia, and with or without a brief loss of consciousness.

Description

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.

Demographics

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

Causes

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

Symptoms of concussion include the following:

• headache
• disorientation as to time, date, or place
• confusion
• dizziness
• 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:

• headache
• poor attention and concentration
• memory difficulties
• anxiety
• depression
• 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.

Diagnosis

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.

Treatment

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.

Prognosis

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.

Prevention

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.

Parental Concerns

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.

Resources

Books

Hergenroeder, Albert C., and Joseph N. Chorley. "Head and Neck Injuries." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman, et al. Philadelphia: Saunders, 2003, pp. 2313–4.

Hodge, Charles J. "Head Injury." In Cecil Textbook of Medicine, 22nd ed. Edited by Lee Goldman, et al. Philadelphia: Saunders, 2003, pp. 2241–2.

Parker, Rolland S. Concussive Brain Trauma: Neurobehavioral Impairment and Maladaptation. Lakeland, FL: CRC Press, 2000.

Ropper, Allan H. "Traumatic Injuries of the Head and Spine." In Harrison's Principles of Internal Medicine, 15th ed. Edited by Eugene Braunwald, et al. New York: McGraw Hill, 2001, pp. 2434–41.

Periodicals

Iverson, G. L., et al. "Cumulative effects of concussion in amateur athletes." Brain Injury 18, no. 5 (2004): 433–43.

Lovell, M., et al. "Return to play following sports-related concussion." Clinics in Sports Medicine 23, no. 3 (2004): 421–41.

Ryan, L. M., and D. L. Warden. "Post concussion syndrome." International Review of Psychiatry 15, no. 4 (2004): 310–6.

Wisniewski, J. F., et al. "Incidence of cerebral concussions associated with type of mouth guard used in college football." Dental Traumatology 20, no. 3 (2004): 143–9.

Organizations

American Academy of Emergency Medicine. 611 East Wells Street, Milwaukee, WI 53202. Web site: www.aaem.org/.

American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211–2672. Web site: www.aafp.org/.

American Academy of Neurology. 1080 Montreal Avenue, St. Paul, MN 55116. Web site: www.aan.com/.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: www.aap.org/default.htm.

American College of Emergency Physicians. PO Box 619911, Dallas, TX 75261–9911. Web site: www.acep.org/.

Brain Injury Association. 105 North Alfred Street, Alexandria, VA 22314. Web site: www.biausa.org/Sportsfs.htm.

International Brain Injury Association. 1150 South Washington Street, Suite 210, Alexandria, VA 22314. Web site: www.internationalbrain.org/.

Web Sites

"Concussion." American Academy of Family Physicians. Available online at www.aafp.org/afp/990901ap/990901e.html (accessed December 8, 2004).

"Concussion." University of Missouri School of Medicine. Available online at www.muhealth.org/~neuromedicine/concussion.shtml (accessed December 8, 2004).

"Facts about Concussion and Brain Injury and Where to Get Help" Centers for Disease Control and Prevention. Available online at www.cdc.gov/doc.do?id=0900f3ec8000d38c (accessed December 8, 2004).

"Head Injury." MedlinePlus. Available online at www.nlm.nih.gov/medlineplus/ency/article/000028.htm (accessed December 8, 2004).

[Article by: L. Fleming Fallon, Jr., MD, DrPH]

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A disturbance in the normal function of nerve cells in the brain due to a blow to the head. Such a blow can cause the brain to bounce against the rigid bone of the skull, resulting in a disruption of blood vessels and a breakdown in the normal flow of messages within the brain. Severe cases of concussion lead to sudden loss of consciousness, commonly called a knock-out. A knock-out may last a few minutes or a few hours and is often accompanied by pallor, slow movements, feebleness of heart beat, shallow breathing, and loss of normal reflex functions. Athletes who have been knocked-out are usually advised to avoid contact or collision sports for at least 3 weeks. In some sports, such as Rugby Union football, this lay-off is mandatory. Boxers suffering from concussion after being knocked out in the ring may also be required to avoid boxing. In Britain, amateur boxers are not allowed to box until 28 days after the first knock-out, 84 days after the second knockout, and 1 year afterthe third knock-out. See also digit symbol substitution test, second impact syndrome. See also Sport Concussion Assessment Tool. [Q2]

Concussion can be defined as a clinical syndrome characterized by immediate and transient impairment of mental functions such as alteration of consciousness, and disturbance of vision or equilibrium, due to mechanical forces. Such results follow all but the mildest blows to the head. In the majority of instances loss of consciousness is of short duration, but severe injuries result in periods of unconsciousness varying from hours to weeks or even months. The greater the duration of unconsciousness and the subsequent post-traumatic amnesia, the greater will be the period of post-concussional disability. Consequently it is important to record the duration of loss of memory following head injuries, not only as an index of severity but also as a guide to ultimate recovery.

It has been estimated that almost one million patients in the UK are admitted to hospital each year following head injuries. The majority of injuries are the consequences of road traffic accidents, which are also often the cause of the most severe injuries. Other causes of head injury include domestic and industrial accidents, sports and recreation, and violent assaults (Teasdale 1995).

The cerebral damage is caused by rotational stresses within the brain, and is likely to be the more severe if the head is in motion at the time of impact. This causes minute haemorrhages and neuronal changes throughout the brain which may be of aetiological importance for the so-called post-concussional syndrome. At the same time it is clear that the principal features of concussion are caused by interference with vital centres in the brain stem. If unconsciousness lasts more than a few hours, it is likely that permanent brain damage has been sustained, with the risk of major psychological disabilities and personality changes that may prevent the patient returning to his former employment or even living equably with his family. The premorbid qualities of the individual will greatly influence his capacity for attaining full recovery, but even the most stable of individuals may suffer to some extent from post-concussional symptoms. These may include headache, dizziness, fatigue, and intolerance of noise, as well as emotional instability and impaired memory and concentration.

Chronic psychological impairment is sometimes seen in professional boxers who have sustained repeated blows to the head without necessarily losing consciousness. In recent times a good deal of attention has been focused on this 'punch-drunk' syndrome, which has led to proposals that boxing should be banned. This is unlikely to happen but greater protection of the head and face of boxers and medical control of those taking part in the sport may do something to minimize the frequency of punch-drunkenness.

(Published 1987)

— F. A. Whitlock

Bibliography
• Teasdale, G. M. (1995). 'Head injury'. Journal of Neurology, Neurosurgery, and Psychiatry, 58/5.

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A violent jar or shock, or the condition that results from such an injury.

• brain c. — loss of consciousness, transient or prolonged, due to a blow to the head; breathing often is unusually rapid or slow. Outward evidence of the injury may include bleeding, sometimes from the nose, and contusions (bruises). There may be residual signs such as local paralysis on recovery.
• spinal cord c. — may lead to temporary paresis or spinal shock, with possible local paralysis continuing after partial recovery.
• c. stunner — a sharp blow to the head sufficient to cause stunning may be used as a prelude to euthanasia or, in laboratory animals, as a means of euthanasia on its own.

IN BRIEF: An injury to the brain, usually from a blow.

Martin suffered a concussion during the accident.

Dansk (Danish)
n. - hjernerystelse, chok

Nederlands (Dutch)
(hersen)schudding, schok

Français (French)
n. - (Méd) commotion cérébrale

Deutsch (German)
n. - Gehirnerschütterung

Ελληνική (Greek)
n. - τράνταγμα, ταρακούνημα, (παθολ.) (εγκεφαλική) διάσειση

Italiano (Italian)
commozione cerebrale

Português (Portuguese)
n. - concussão (f) (Med.)

Русский (Russian)
сотрясение

Español (Spanish)
n. - conmoción cerebral

Svenska (Swedish)
n. - häftig skakning, hjärnskakning

中文（简体）(Chinese (Simplified))
激动, 震荡, 冲击

中文（繁體）(Chinese (Traditional))
n. - 激動, 震蕩, 衝擊

한국어 (Korean)
n. - 진동, 충격, 협박

日本語 (Japanese)
n. - 衝撃, 脳しんとう

العربيه (Arabic)
‏(الاسم) رجه, ارتجاج‏

עברית (Hebrew)
n. - ‮הלם, זעזוע-מוח‬

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