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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.
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.

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.
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.
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 Muhammaed Ali, whose parkinsonism 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:
  • headache
  • disorientation as to time, date, or place
  • confusion
  • dizziness
  • vacant stare or confused expression
  • incoherent or incomprehensible speech
  • incoordination 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 so, it will be for several minutes at the most. More 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:
  • 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."


It is very important for those attending a person with 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 patient is closely monitored for neurological symptoms which 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 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.


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 when bicycling, skiing, or horseback riding. Soccer players should avoid heading the ball when it is kicked at high velocity from close range. Playground equipment should be underlaid 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.



Evans, R. Neurology and Trauma. W. B. Saunders Co., 1996.


American Academy of Neurology. 1080 Montreal Ave., St. Paul, MN 55116. (612) 695-1940.

Key terms

Amnesia — A loss of memory that may be caused by brain injury, such as concussion.
Parkinsonism — A neurological disorder that includes a fine tremor, muscular weakness and rigidity, and an altered way of walking.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a violent jar or shock, or the condition that results from such an injury.
concussion of the brain alteration of consciousness, transient or prolonged, due to a blow to the head; it may be followed by transient amnesia, vertigo, nausea, and weak pulse. Breathing often is unusually rapid or slow. Outward evidence of the injury may include bleeding and contusions (bruises). When consciousness is regained, the victim is likely to have severe headache and, possibly, blurred vision. If severely injured, the victim may lapse into a coma.

Concussion is a type of traumatic brain injury (see also head injury). In addition to the primary injury, concussion can precipitate an increase in intracranial pressure or other neurological sequelae such as bleeding that can emerge several hours or days after the trauma. It is critical for health care providers to monitor these secondary tissue damages. Education of the patient and family is important regarding signs and symptoms of an increase in intracranial pressure and when to seek emergency care. Most people, however, recover from a concussion with no permanent neurological deficits. Rest is the usual treatment. acetaminophen is usually prescribed for the associated headache.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


1. A violent shaking or jarring.
2. An injury of a soft structure, as the brain, resulting from a blow or violent shaking. Synonym(s): commotio
[L. concussio, fr. con- cutio, pp. -cussus, to shake violently]
Farlex Partner Medical Dictionary © Farlex 2012


1. A violent jarring; a shock: The concussion from the explosion broke windows three blocks away.
2. An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.

con·cus′sive (-kŭs′ĭv) adj.
con·cus′sive·ly adv.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Neurology A severe brain injury, due to a violent blow or shaking, which is characterized by immediate and transient impairment of brain function and one or more of the following: loss of consciousness, amnesia, seizure, or a change in mental status, which may be accompanied by defects in cognition, vision, equilibrium. See Transient ischemic attack. Cf Contusion Sports medicine A traumatically induced alteration in mental status; impairment of brain function caused by injury to the head; speed and degree of recovery depend on severity of the brain injury. See Labryinthine concussion.
Concussion–per Colorado medical society
Grade I Mild concussion 'Having the bell rung', 'head ding' Confusion without amnesia or loss of consciousness; difficult to detect Management Remove from game, examine immediately for amnesia, postconcussive symptoms; return to game in no less than 20 minutes; three grade I concussions should end player's season; no contact sports for ≥ 3 months
Grade II Moderate concussion Confusion with amnesia, no loss of consciousness; post-traumatic and retrograde amnesia may occur in severe cases; athlete should be evaluated for 24 hours Management Remove permanently from game; examine repeatedly for intracranial problems; return to practice ≥ 1 week; return to playing ≥ 1 month or end athlete's season; season ends if ≥ 3 grade II concussions or abnormality by CT or MRI
Grade III Severe concussion Loss of consciousness Management Transport to hospital with cervical spine immobilization; full neurologic examination; return to practice ≥ 2 weeks; return to play ≥ 1 month or end athlete's season; season ended if ≥ 2 grade II concussions or any abnormality by CT or MRI
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


1. A violent shaking or jarring.
2. An injury of a soft structure, as the brain, resulting from a blow or violent shaking; with partial to complete loss of function.
[L. concussio, fr. con- cutio, pp. -cussus, to shake violently]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A ‘shaking-up’ of the brain, from violent acceleration or deceleration of the head, causing unconsciousness lasting for seconds to hours. The injury is probably associated with some bleeding inside the brain and in many cases actual destruction of nerve tissue occurs. People who have suffered concussion require expert clinical observation in hospital for at least 24 hours.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

Patient discussion about concussion

Q. What is a concussion? How do you treat it? My child fell and hit his head and passed out. We went to the hospital and they say it’s a concussion and he’ll be fine. Can some one explain what it is exactly?

A. When your brain gets hit hard- this is concussion. But there’s a nice short video about it with a nice pediatrician that explains it:

More discussions about concussion
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The doctor decided to take Steve off, do a concussion test when the incident happened," Kountouris told reporters.
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Data collected between 1996 and 2001 showed that NFL players were sidelined for six or fewer days after a concussion.
Giguere also said that doctors should tell patients with minor concussions to report loss of smell or anxiety in the weeks following their injury.
Statin users who had concussions continued to have a reduced risk of developing dementia after adjustment for patient characteristics, use of other cardiovascular medications, dosage, and depression risk.
The guidelines recommend that immediately after a concussion from any cause, children should refrain from physical and mental activity, including school and sports, and then gradually resume normal activities, the AP reported.
Experts at Cardiff Metropolitan University analysed rugby union data from the 2015/16 season in Wales and England, and found concussion was three times higher than the second most frequent injury, thigh haematoma, also known as dead leg.
The results of this study indicate that collegiate rugby players with a history of multiple concussions have poorer short-term working memory compared with players with [less than or equal to] 1 concussion.