concussion

The concussion - Brief unconsciousness, usually following a violent blow to the head. The loss of consciousness is due to a brief disturbance of the electrical activity in the brain.

Common symptoms following concussion include confusion, inability to remember events that occurred just prior to the injury, dizziness, blurred vision, and vomiting. Anyone who has been concussed, however briefly, should see a doctor as soon as possible.

Persistent symptoms, or new ones such as drowsiness, difficulty in breathing, repeated vomiting, or visual disturbances, could signify brain damage or an extradural haemorrhage, and medical advice should be sought without delay. Repeated concussion can cause punch-drunk syndrome. (See also head injury.)