Concussion refers to alteration in consciousness secondary to closed head injury. Following are the signs and symptoms of concussion: - amnesia - confusion - incoordination - decreased alertness and concentration - loss of consciousness - personality changes - vomiting - headache Reference: https://www.cdc.gov/headsup/basics/concussion_symptoms.html Image via: https://www.youtube.com/watch?v=55u5Ivx31og