Health Encyclopedia

Concussion

Definition

A concussion may occur when the head hits an object, or a moving object strikes the head. A concussion is a less severe type of brain injury. It may also be called a traumatic brain injury.

A concussion can affect how the brain works. The amount of brain injury and how long it will last depends on how severe the concussion is. A concussion may lead to headaches, changes in alertness, loss of consciousness, memory loss, and changes in thinking.

Alternative Names

Brain injury - concussion; Traumatic brain injury - concussion; Closed head injury - concussion

Causes

A concussion can result from a fall, sports activities, vehicular accidents, assault, or other direct injury to the skull. A big movement of the brain (called jarring) in any direction can cause a person to lose alertness (become unconscious). How long the person stays unconscious may be a sign of how bad the concussion is.

Concussions do not always lead to loss of consciousness. Most people never pass out. They may describe seeing all white, all black, or stars. A person can also have a concussion and not realize it.

Watch this video about:
Concussion

Symptoms

Symptoms of a milder concussion can include:

Acting somewhat confused, feeling unable to concentrate, or not thinking clearly
Being drowsy, hard to wake up, or similar changes
Headache
Loss of consciousness for a fairly short period of time
Memory loss (amnesia) of events before the injury or right after
Nausea and vomiting
Seeing flashing lights, light sensitivity
Feeling like you have "lost time"
Sleep abnormalities

The following are emergency symptoms of a more severe head injury or concussion. Seek medical care right away if there are:

Changes in alertness and consciousness
Confusion that does not go away
Seizures
Muscle weakness on one or both sides of the body
Pupils of the eyes that are not equal in size
Symptoms in just one eye
Unusual eye movements
Repeated vomiting
Walking or balance problems
Unconsciousness for a longer period of time or that continues (coma)

Head 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.

Exams and Tests

The health care provider will perform a physical exam. The person's nervous system will be checked. There may be changes in the person's pupil size, thinking ability, coordination, and reflexes.

Tests that may be done include:

Blood and urine tests
EEG (brain wave test) may be needed if seizures continue
Head CT (computerized tomography) scan
MRI of the brain (magnetic resonance imaging) of the brain
X-rays

Treatment

For a mild head injury, no treatment may be needed. But be aware that the symptoms of a head injury can show up later.

Your providers will explain what to expect, how to manage any headaches, how to treat your other symptoms, when to return to sports, school, work, and other activities, and signs or symptoms to worry about.

Children will need to be watched and make activity changes.
Adults also need close observation and activity changes.

Both adults and children must follow the provider's instructions about when it will be possible to return to sports.

You will likely need to stay in the hospital if:

Emergency or more severe symptoms of head injury are present
There is a skull fracture
There is any bleeding under your skull or in the brain

Outlook (Prognosis)

Healing or recovering from a concussion takes time. It may take days to weeks, or even months. During that time you may:

Be withdrawn, easily upset, or confused, or have other mood changes
Have a hard time with tasks that require memory or concentration
Have mild headaches
Be less tolerant of noise
Be very tired
Feel dizzy
Have blurry vision at times

These problems will probably recover slowly. You may want to get help from family or friends for making important decisions.

In a small number of people, symptoms of the concussion do not go away. The risk for these long-term changes in the brain is higher after more than one concussion.

Seizures may occur after more severe head injuries. You or your child may need to take anti-seizure medicines for a period of time.

More severe traumatic brain injuries may result in many brain and nervous system problems.

When to Contact a Medical Professional

Contact the provider if:

A head injury causes changes in alertness.
A person has other worrisome symptoms.
Symptoms do not go away or are not improving after 2 or 3 weeks.

Contact the provider right away if the following symptoms occur:

Increased sleepiness or difficulty waking up
Stiff neck
Changes in behavior or unusual behavior
Changes in speech (slurred, difficult to understand, does not make sense)
Confusion or problems thinking straight
Double vision or blurred vision
Fever
Fluid or blood leaking from the nose or ears
Headache that is getting worse, lasts a long time, or does not get better with over-the-counter pain relievers
Problems walking or talking
Seizures (jerking of the arms or legs without control)
Vomiting more than 3 times

If symptoms do not go away or are not improving a lot after 2 or 3 weeks, talk to your provider.

Prevention

Not all head injuries can be prevented. Increase safety for you and your child by following these steps:

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 may have been drinking alcohol or is otherwise impaired.

References

Liebig CW, Congeni JA. Sports-related traumatic brain injury (concussion). In: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 708.

McClincy MP, Olgun ZD, Dede O. Orthopedics. In: Zitelli, BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 22.

Papa L, Goldberg SA. Head trauma. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 33.

Trofa DP, Caldwell J-M E, Li XJ. Concussion and brain injury. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller's Orthopaedic Sports Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 126.

Review Date:11/13/2021
Reviewed By:Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 04/11/2023.

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