Concussion

Definition

Concussion is the term used to refer to the consequences of mild head injury. These injuries (frequently sustained in motor vehicle accidents and sporting activities) are not associated with severe skull fractures or bleeding within the substance of the brain. They are, however, sufficiently severe to cause someone to be ‘knocked out’ and are usually associated with a period of memory loss.

Concussion seldom results in permanent brain damage, but may cause troublesome symptoms well after the initial injury has settled.

What to do if someone appears concussed

Someone who has been concussed is usually briefly disorientated, and should be allowed to rest quietly until it is clear that their injuries are not more severe. If there is any chance that a neck injury has also occurred, the patient should not be moved until the arrival of emergency medical personnel.

Unless the injury is very mild, the patient should be examined by a physician in a casualty room for signs of neurological injury. A brain scan or neck x-rays may be obtained. In a few cases, particularly where the patient has not regained full alertness, observation for a short time in hospital may be called for.

Signs and symptoms

True concussion almost always leaves a brief gap in memory around the time of the injury. This memory loss includes that for events immediately before the injury (retrograde amnesia) as well as new memories for a short period from the time after the accident (anterograde amnesia). The more severe the injury, the longer the period of memory loss. With time, this memory loss improves, but most people are left with a permanent lack of memory of their accident, as well as for events for a short time before and afterwards.

A further consequence of concussion are lingering ‘post-concussive’ symptoms that may persist well after the initial injury has settled. Headache, fatigue, dizziness, irritability, poor concentration, disturbed sleep as well as depression and anxiety may all occur. These symptoms may be surprisingly troublesome, since they often seem out of proportion to the original injury, and may persist for weeks or many months in some cases. Supportive encouragement, physical therapy, and medications such as anti-depressants may be helpful.

Finally, it should be emphasized that concussion is a mild form of true brain injury, and repeated concussions may lead to permanent damage. In fact, it is thought that one concussion makes a person more vulnerable to concussions later on if they have minor head injures again. Rarely, two concussions closely spaced may result in the so-called ‘second impact syndrome’ and lead to fatal brain swelling.

Written by Dr Andrew Rose-Innes, Yale University School of Medicine, 2007