A concussion is a minor traumatic brain injury (TBI) that may occur when the head hits an object, or a moving object strikes the head.It can affect how your brain works for a while. A concussion can lead to a bad headache, changes in alertness, or loss of consciousness.

Causes, incidence, and risk factors

ConcussionA concussion can result from a fall, sports activities, and car accidents. A big movement of the brain (called jarring) in any direction can cause you to lose alertness (become unconscious). How long you stay unconscious may be a sign of the severity of the concussion.However, concussions don't always involve a loss of consciousness. Most people who have a concussion never pass out, but they may describe seeing all white, black, or stars. You can have a concussion and not realize it.


Symptoms of a concussion can range from mild to severe. They can include:Acting confused, feeling spacey, or not thinking straightBeing drowsy, hard to wake up, or similar changesHeadacheLoss of consciousnessMemory loss (amnesia) of events before the injury or right afterNausea and vomitingSeeing flashing lightsFeeling like you have "lost time"The following are emergency symptoms of a concussion. Seek immediate medical care if there are:Changes in alertness and consciousnessConvulsions (seizures)Muscle weakness on one or both sidesPersistent confusionRemaining unconsciousness (coma)Repeated vomitingUnequal pupilsUnusual eye movementsWalking problemsHead injuries that cause a concussion often occur with injury to the neck and spine. Take special care when moving people who have had a head injury.While recovering from a concussion, you may:Be withdrawn, easily upset, or confusedHave a hard time with tasks that require remembering or concentratingHave mild headachesBe less tolerant of noise

Signs and tests

The doctor will perform a physical exam and check your nervous system. There may be changes in your pupil size, thinking ability, coordination, and reflexes.Tests that may be performed include:EEG (brain wave test) may be needed if seizures continueHead CT scanMRI of the head


A more serious brain injury that involves bleeding or brain damage must be treated in a hospital.Healing or recovering from a concussion takes time. It may take days, weeks, or even months for a child's condition to improve. Parents and caregivers must learn how to treat the child's symptoms, how to monitor for problems, and when to allow the child to return to normal activities.

Expectations (prognosis)

Healing or recovering from a concussion takes time. It may take days, weeks, or even months. You may be irritable, have trouble concentrating, be unable to remember things, have headaches, dizziness, and blurry vision. These problems will probably go away slowly. You may want to get help from family or friends before making important decisions.


Long-term problems are rare but may include:Brain swelling (which can be life threatening), if you have a second concussion while still recovering from the first oneLong-term changes in the brain (if you have future brain injuries)Symptoms of the concussion stay for a long period of time (in a small group of patients)

Calling your health care provider

Call your health care provider if a head injury causes changes in alertness or produces any other worrisome symptoms.If symptoms do not go away or are not improving after 2 or 3 weeks, talk to your doctor.Call the doctor if the following symptoms occur:Changes in behavior or unusual behaviorChanges in speech (slurred, difficult to understand, does not make sense)ConfusionDifficulty waking up or becoming more sleepyDouble vision or blurred visionFeverFluid or blood leaking from the nose or earsHeadache that is getting worse, lasts a long time, or does not get better with over-the-counter pain relieversProblems walking or talkingSeizures (jerking your arms or legs without control)Vomiting more than three times


Although you can't entirely prevent injuries in children, parents can take some simple steps to keep their children from getting head injuries.To prevent head injuries in adults:Always use safety equipment during activities that could cause a head injury. These include seat belts, bicycle or motorcycle helmets, and hard hats.Learn and follow bicycle safety recommendations.Do NOT drink and drive. Do NOT allow yourself to be driven by someone who you know or suspect has been drinking alcohol or is otherwise impaired.


Ropper AH, Gorson KC. Clinical practice: concussion. N Engl J Med. 2007;356:166-172.Hunt T, Asplund C. Concussion assessment and management. Clin Sports Med. 2009;5-17.Biros MH, Heegard WG. Head injury. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 38.

Review Date: 1/30/2012
Reviewed By: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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