A concussion is a mild type of traumatic brain injury (mTBI) that can change the way the brain normally works.
People with concussions can experience symptoms that are:
- Physical, such as headache and blurred vision
- Cognitive, such as difficulty focusing
- Emotional, such as irritability
- Sleep-related, such as fatigue, sleeping more than usual
These symptoms may last several minutes, days, weeks, or even longer in some cases. Most concussions are relatively minor and will resolve.
Concussions can be caused by trauma that is either:
- A bump, blow, or jolt to the head, such as a fall or collision that causes direct impact
- A fall or a blow to the body that causes the head to move quickly back and forth(whiplash); even though the head does not suffer a direct hit, the brain is jostled inside skull
Whether or not a person has suffered a concussion is not always obvious. A loss of consciousness happens in only about 10% of concussion cases.1,2 Standard neurological imaging, such as CT scans and MRIs, are typically normal after concussions but are used to assess for more serious injuries.
How does a concussion occur?
Many people think of a concussion as a sudden, one-time traumatic event. However, a concussion is due to a series of metabolic (biochemical) changes in the brain that are set off by the traumatic event.
- Following the injury, the brain cells may not get enough energy and nutrients to work properly, causing impairment in brain function
- As the brain cells undergo metabolic change and recovery, the symptoms of impairment can also change
- Recovery may take a few minutes or a few months—or even longer—depending on the individual and the injury’s severity
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The affected brain cells are particularly vulnerable to sustaining further damage during the concussion recovery period.
What to do when a concussion is suspected
A person who is suspected of suffering a concussion should be evaluated as soon as possible. Until the evaluation is completed, it should be assumed that the person has suffered a concussion and he or she should be:
- Removed from athletic play
- Prohibited from driving or operating large machinery
- Removed from other situations that may endanger the patient or others
The CDC recommends that a person with a concussion be seen by a doctor. A doctor can provide a medical evaluation and instructions for recovery.
Concussions in sports
Any athlete who is suspected of suffering a concussion should not be allowed to return to play. Instead, the athlete should be evaluated immediately, preferably in a quiet area such as a locker room, and monitored over the next 24 to 48 hours for symptoms.
This approach may seem overly cautious to some people, particularly competitive athletes who want to get back in the game. However, a person who has a concussion and then suffers a second head injury risks a longer recovery time and further injury to the brain.
This article discusses the risk factors, symptoms, diagnoses and rehabilitation typically associated with concussion. Also included is a list of sports that have the highest rates of concussion.
- McCrory P, Meeuwisse W, Johnston K, et al. Consensus statement on concussion in sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008. Br J Sports Med 2009;43(Suppl 1):i76–90.
- Benson BW, Hamilton GM, Meeuwisse WH, et al. Is protective equipment useful in preventing concussion? A systematic review of the literature. Br J Sports Med 2009;43(Suppl 1):i56–67.