What is Concussion?

Legal Definition
Concussion, also known as minor head trauma or mild traumatic brain injury (mTBI) is the most common type of traumatic brain injury. It is typically defined as a head injury with a temporary loss of brain function. Symptoms include a variety of physical, cognitive, and emotional symptoms, which may not be recognized if subtle. A variety of signs accompany concussion including headache, feeling in a fog, and emotional changeability. Physical signs (such as loss of consciousness or amnesia), behavioral changes (such as irritability), cognitive impairment (such as slowed reaction times), or sleep disturbances. Fewer than 10% of sports-related concussions among children are associated with loss of consciousness.

Common causes include sports injuries, bicycle accidents, car accidents, and falls, the latter two being the most frequent causes among adults. In addition to a blow to the head, concussion may be caused by acceleration forces without a direct impact, and on the battlefield, MTBI is a potential consequence of nearby explosions. It is not clear exactly what damage is done and how the symptoms are caused, but stretching of axons and changes in ion channels are involved. Cellular damage has reportedly been found in concussed brains, but it may have been due to artifacts from the studies. It is currently thought that structural and neuropsychiatric factors may both be responsible for the effects of concussion.

Treatment involves monitoring as well as physical and cognitive rest (reduction of such activities as school work, playing video games and text messaging). Symptoms usually resolve within three weeks, though they may persist or complications may occur.

The rate at which concussion occurs is not accurately known, but is estimated to be more than 6 per 1,000 people. Those who have had one concussion seem more susceptible to another, especially if the new injury occurs before symptoms from the previous concussion have completely resolved. There is also a negative progressive process in which smaller impacts cause the same symptom severity. Repeated concussions may increase the risk in later life for dementia, Parkinson's disease, or depression.
-- Wikipedia
Legal Definition
Civ. law. The unlawful forcing of another by threats of violence to give something of value. It differs from robbery in this, that in robbery the thing is taken by force, while in concussion it is obtained by threatened violence. Hein. Lec. El, 1071
-- Bouviers Law Dictionary
Legal Definition
In the civil law. The unlawful forcing of another by threats of violence to give something of value. It differs from robbery, in this; That in robbery the thing ls taken by force, while in concussion it is obtained by threatened violence, Helnec. Elem. ยง 1071. In medical jurisprudence. Co.ncusslon of the brain is a jarring of the brain substance, hy a fall, blow, or other external injury, without laceration of its tissue, or with only microscopical laceration. Maynard v. Railroad Ch, 43 Or. 63, 72 Pac. 590.
-- Black's Law Dictionary
Legal Definition
Extortion; compulsion by threats and without force.
-- Ballentine's Law Dictionary