Classic concussion is a disorder with decreased consciousness for up to 6 hours, as well as retrograde and posttraumatic amnesia. Classic concussion is a form of cerebral concussions caused as a result of mechanical force to the brain which temporarily influences the brain functioning. Common causes of this disorder include falls, car accidents, sports injuries such as during boxing, and bicycle accidents. The signs of a concussion include unconsciousness, memory loss, confusion, dizziness, nausea, and slowed reaction to stimuli.