|Other names||Mild brain injury, mild traumatic brain injury (mTBI), mild head injury (MHI), minor head trauma|
|Acceleration (g-forces) can exert rotational forces in the brain, especially the midbrain and diencephalon.|
|Specialty||Emergency medicine, neurology|
|Symptoms||Headache, trouble with thinking, memory or concentration, nausea, blurry vision, sleep disturbances, mood changes|
|Duration||Up to 4 weeks|
|Causes||Motor vehicle collisions, falls, sports injuries, bicycle accidents|
|Risk factors||Drinking alcohol|
|Diagnostic method||Based on symptoms|
|Prevention||Helmets when bicycling or motorbiking|
|Treatment||Physical and cognitive rest for a day or two with a gradual return to activities|
|Medication||Paracetamol (acetaminophen), NSAIDs|
|Frequency||6 per 1,000 people a year|
Concussion, also known as mild traumatic brain injury (mTBI), is typically defined as a head injury that temporarily affects brain functioning. Symptoms may include loss of consciousness (LOC); memory loss; headaches; difficulty with thinking, concentration or balance; nausea; blurred vision; sleep disturbances; and mood changes. Any of these symptoms may begin immediately, or appear days after the injury. It is not unusual for symptoms to last 2 weeks in adults and 4 weeks in children. Fewer than 10% of sports-related concussions among children are associated with loss of consciousness.
Common causes include motor vehicle collisions, falls, sports injuries and bicycle accidents. Risk factors include drinking alcohol and a prior history of concussion. The mechanism of injury involves either a direct blow to the head or forces elsewhere on the body that are transmitted to the head. This is believed to result in neuron dysfunction, as there is increased glucose requirements but not enough blood supply. Diagnosis requires less than 30 minutes of LOC, memory loss of less than 24 hours, and a Glasgow coma scale score of 13 to 15. Otherwise, it is considered a moderate or severe traumatic brain injury.
Prevention of concussions includes the use of a helmet when bicycling or motorbiking. Treatment generally involves physical and cognitive rest for a day or two, with a gradual return to activities. Prolonged periods of rest may slow recovery and result in greater depression and anxiety.Paracetamol (acetaminophen) or NSAIDs may be recommended to help with a headache.Physiotherapy may be useful for persistent balance problems; cognitive behavioral therapy may be useful for mood changes. Evidence to support the use of hyperbaric oxygen therapy and chiropractic therapy is lacking.
Worldwide, concussions are estimated to affect more than 3.5 per 1,000 people a year. Concussions are classified as mild traumatic brain injuries and are the most common type of TBIs. Males and young adults are most commonly affected. Outcomes are generally good. Another concussion before the symptoms of a prior concussion have resolved is associated with worse outcomes. Repeated concussions may also increase the risk in later life of chronic traumatic encephalopathy, Parkinson's disease and depression.