(concussion) A concussion is a type of brain injury. It involves a short loss of normal brain function. It happens when a hit to the head or body causes your head and brain to move rapidly back and forth. This sudden movement can cause the brain to bounce around or twist in the skull, creating chemical changes in your brain. Sometimes it can also stretch and damage your brain cells. Sometimes people call a concussion a "mild" brain injury. It is important to understand that while concussions may not be life-threatening, they can still be serious. Concussions are a common type of sports injury. Other causes of concussions include blows to the head, bumping your head when you fall, being violently shaken, and car accidents. Symptoms of a concussion may not start right away; they may start days or weeks after the injury. Symptoms may include a headache or neck pain. You may also have nausea, ringing in your ears, dizziness, or tiredness. You may feel dazed or not your normal self for several days or weeks after the injury. Consult your health care professional if any of your symptoms get worse, or if you have more serious symptoms such as: Convulsions or seizures; Drowsiness or inability to wake up; A headache that gets worse and does not go away; Weakness, numbness, or decreased coordination; Repeated vomiting or nausea; Confusion; Slurred speech; Loss of consciousness. To diagnose a concussion, your health care provider will do a physical exam and will ask about your injury. You will most likely have a neurological exam, which checks your vision, balance, coordination, and reflexes. Your health care provider may also evaluate your memory and thinking. In some cases, you may also have a scan of the brain, such as a CT scan or an MRI. A scan can check for bleeding or inflammation in the brain, as well as a skull fracture (break in the skull). Most people recover fully after a concussion, but it can take some time. Rest is very important after a concussion because it helps the brain to heal. In the very beginning, you may need to limit physical activities or activities that involve a lot of concentration, such as studying, working on the computer, or playing video games. Doing these may cause concussion symptoms (such as headache or tiredness) to come back or get worse. Then when your health care provider says that it is ok, you can start to return to your normal activities slowly. Centers for Disease Control and Prevention

(concussion) A violent jar or shock, or the condition which results from such an injury.

(concussion) Traumatic brain injury as a result of the action of a mechanical force on the head.

(concussion) Traumatic brain injury that results in temporary disturbance of cerebral function without radiographic changes.

A nonspecific term used to describe transient alterations or loss of consciousness following closed head injuries. The duration of UNCONSCIOUSNESS generally lasts a few seconds, but may persist for several hours. Concussions may be classified as mild, intermediate, and severe. Prolonged periods of unconsciousness (often defined as greater than 6 hours in duration) may be referred to as post-traumatic coma (COMA, POST-HEAD INJURY). (From Rowland, Merritt's Textbook of Neurology, 9th ed, p418)

A concussion is an alteration in mental function or level of awareness caused by a head injury. A concussion may involve a loss of consciousness, can occur without obvious damage to brain structures, and lasts less than 6 hours.

Concussion, or mild traumatic brain injury (MTBI), is common among contact and collision sports participants. One definition of concussion is a condition in which there is a traumatically induced alteration in mental status, with or without an associated loss of consciousness (LOC).

A concussion is a traumatic brain injury that affects your brain function. Effects are usually temporary but can include headaches and problems with concentration, memory, balance and coordination.

Concussion (mild traumatic brain injury) is a closed head injury due to a direct blow to the head or deceleration of the head from an impulsive force that results in a change in mental status. https://www.cdc.gov/HEADSUP/

Concussion, a temporary loss of brain function typically resulting from a relatively mild injury to the brain, not necessarily associated with unconsciousness. Concussion is among the most commonly occurring forms of traumatic brain injury and is sometimes referred to as mild traumatic brain injury...