A concussion is an injury-induced alteration in mental function or level of awareness that may involve a loss of consciousness, can occur without obvious damage to brain structures, and lasts less than 6 hours.
In concussion, no brain damage can be detected on imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI). Yet brain cells are temporarily damaged or dysfunctional. The person has temporary symptoms of brain dysfunction.
People who have a concussion may temporarily feel dazed or mildly confused. Some people answer questions slowly. Some people may not realize they have had a concussion. People may be light-headed or have a headache, double vision, sensitivity to light, poor balance, or clumsiness. Consciousness may be lost for a brief time, rarely for more than 15 minutes. Memory of events just before or just after the injury may be lost.
Postconcussion syndrome refers to certain symptoms that sometimes occur for up to a few weeks after a concussion. People may experience headache, the sensation of spinning, light-headedness, fatigue, poor memory, inability to concentrate, sensitivity to light or noise, irritability, depression, and anxiety. People may develop impaired thinking, particularly people who had emotional problems before the concussion. Postconcussion syndrome symptoms are common during the week after concussion and commonly resolve during the second week. However, sometimes, symptoms persist for months or, rarely, years. People who have had a concussion also seem to be more susceptible to another one, particularly if the new injury occurs before symptoms from the previous concussion have completely gone away.
To diagnose a concussion, doctors need to make sure brain structures are not damaged. The use of CT, MRI, or both may be needed. If there is no structural brain damage, only the symptoms need be treated. For concussion, acetaminophen is given for pain. Aspirin or another nonsteroidal anti-inflammatory drug (NSAID—see Nonopioid Analgesics : Nonsteroidal Anti-Inflammatory Drugs) should not be taken because they interfere with blood clotting and may contribute to bleeding from damaged blood vessels. Rest is the best treatment for a concussion.
Treatment for postconcussion syndrome is based on the severity of the symptoms. Rest and close observation are important. People who experience emotional difficulties may need psychotherapy. Repeated concussions may increase a person’s risk in later life for dementia, Parkinson disease, and depression. People should not return to contact sports after a concussion until all ill effects have resolved and medical evaluation has been completed.