What is Concussion?

Concussion overview

A concussion is an injury to the brain caused by a direct or indirect blow to the head.  Concussions do not include injuries where there is bleeding and swelling under the skull or into the brain (contusion or hematoma).


The formal medical definition of a concussion is “a clinical syndrome characterized by an immediate and transient alteration of mental status/processing and level of consciousness, resulting from a mechanical force or trauma.” [American Academy of Neurology, 2004]


 A concussion occurs when the head hits or is hit by an object, or when the brain is jarred against the skull, with sufficient force to cause a temporary loss of function of the higher cortical areas of the brain.  A concussion may include bruising or swelling of the head.  The injured person may remain conscious or lose consciousness briefly, and may result in short-term and/or long-term symptoms after the blow.

What are the Levels of a Concussion?

There is no universal agreement on the grades of severity for a concussion. There are at least 16 different guidelines for concussion and return to play. Most guidelines, however, recognize different grades of concussions and share similar recommendations for return to sports involvement (assuming that is the cause).
Concussion can be mild or severe:
-A mild concussion may involve no loss of consciousness (feeling "dazed") or a very brief loss of consciousness (being "knocked out").
-A severe concussion may involve prolonged loss of consciousness with a delayed return to normal.

Who tends to suffer from concussion?

Each year, over 1.1 million adults and children in the United States sustain a traumatic brain injury (TBI), resulting in more than 4,000 individuals sustainning a TBI on a daily basis. One million people are treated and released annually from hospital emergency rooms after sustaining a brain injury. The costs related to brain injury are staggering: exceeding 48 billion dollars per year. Brain injury claims the lives of more than 50,000 people and leaves more than 80,000 individuals with lifelong disabilities each year. More than 12% of the disabilities resulting from brain injury are concussion. Concussion is a frequent cause of hospital admissions, with an estimate of more than 600,000 cases per year in the United States. [American Brain Injury Association, 2004].
Concussion is a common occurrence in sports. According to the Centers for Disease Control (CDC) more than 300,000 American athletes, most of them in high school or college, sustain concussions or other mild to moderate brain injuries each year. One third of these brain injuries occur in football. Research estimates find that from 4 to 20 percent of college and high school football players will sustain a brain injury over the course of one season. The risk of concussion in football is three to six times higher in players with a previous concussion. The rate of concussion is higher in the United States as compared to other countries due to football being a very popular sport.