A concussion is an injury to the brain, usually resulting from a direct blow to the head. It is believed that the force of the blow causes the bulk of the brain to rotate slightly with respect to the brain stem, causing disruption in those parts of the brain where the rotational stresses are greatest.

The physical effects of the concussion itself don't show up on CT scanning. The CT scan is used to rule out other, potentially much more dangerous, damage from the impact, including skull fracture and bleeding in or around the brain. If the CT scan is negative and the patient has a normal neurological examination, overnight observation is usually not needed. However, slight neurological changes are not uncommon with concussions, and being held overnight does not necessarily indicate a more serious injury.

The effects of a concussion may resolve in a few days, or they may last for weeks or months. These long-term effects may include memory problems, difficulty concentrating, increased sensitivity to light and/or noise, sleep disturbance, and mood changes, making up the "post-concussion syndrome." In addition, the risk of developing epilepsy is doubled for up to 5 years after suffering a concussion.

The effects of concussions are also cumulative: Having a second concussion, especially before complete recovery from the first one, increases the chances of long-term and even permanent adverse effects, and many professional athletes have been forced to retire due to the effects of multiple concussions. Studies of the brains of former athletes have shown that multiple concussions can result in what is called chronic traumatic encephalopathy, which is basically a severe, lifelong post-concussion syndrome.

NOTE: As a precautionary measure, David Wright has been placed on the 15-day disabled list by the Mets.
Source(s):
http://content.nejm.org/cgi/content/full/356/2/166
http://www.mayoclinic.com/health/concussion/DS00320
http://www.cnn.com/2009/HEALTH/01/26/athlete.brains/index.html
http://www.nytimes.com/2009/08/17/sports/baseball/17wright.html

Asker's Rating:

Permalink | Report