The brain is well protected inside the bony encasement of the skull, cushioned by a surrounding layer of spinal fluid. But sufficient force can cause damage to delicate brain tissue, and even minor injury can result in impairment of cognitive function and disturbance or mood and behavior.  In a concussion, a mild brain injury, there may be no loss of consciousness, but the brain is injured and temporarily not working properly.  The person may be confused or agitated, and may not remember what happens during this time.  Significant brain injury can occur even when the person does not actually hit their head against anything, as in the “whiplash” injury sustained in a car accident, when the forces can cause a twisting of brain tissue, resulting in “micro-tears,” swelling and inflammation that may not be visible on a brain scan.

In a mild head injury or concussion, there may be only very brief or no loss of consciousness. During a sports game, the person may not realize that they are injured, and may not be the best judge of whether or not to continue playing.  But the injured brain is more vulnerable to further injury, and the dazed player is less able to avoid injury.  Headache, dizziness, and nausea may persist for days or weeks, accompanied by fatigue, irritability, and poor concentration.  Both physical and mental rest are important for recovery, with time off from school or work.  Sometimes, this kind of injury can trigger or worsen anxiety or depression, and emotional and academic support should be provided.