Concussion is synonymous with mild traumatic brain injury (TBI), which is a head injury with a Glasgow Coma Scale (GCS) of 13-15 accompanied by an alteration of brain function. The term concussion is also used in the medical literature to describe the constellation of symptoms following a mild TBI (ie, postconcussion syndrome). TBI is not synonymous with traumatic head injury, which is even more common but lacks the neuronal dysfunction that is diagnostic of concussion.

Concussion most commonly results from direct contact injury to the head secondary to motor vehicle accidents, occupational hazards, falls, recreational accidents, contact sports, combat, and assault. Acceleration or deceleration forces can result in mild brain injury. Concussion occurs more commonly in younger patients (first 4 decades of life) and the incidence is more than 2 times higher in males than females.

Acute symptoms of a concussion occur as a result of disruption of neuronal function and include confusion and impaired awareness, amnesia, headache, dizziness, and incoordination. In the following hours to days, a postconcussion syndrome may develop, which is characterized by headaches, photophobia, phonophobia, attentional and mood disturbances, sleep dysregulation, and dizziness or vertigo. Focal neurologic deficits are uncommon and should prompt evaluation for other causes. Brain imaging in concussion is frequently normal, although imaging is imperative to rule out more severe traumatic injuries. Symptoms most often occur within minutes to hours. More delayed symptom onset should lead to a consideration of other possible causes.

Related topic: pediatric abusive head trauma