A coup-contrecoup injury is a term applied to head injuries and most often cerebral contusions and traumatic subarachnoid hemorrhage. It refers to the common pattern of injury whereby damage is located both at the site of impact (often less marked) and on the opposite side of the head to the point of maximum external trauma.
The impact accelerates first the skull, at which point the brain immediately subjacent to the point of impact may be damaged as it is forcibly impinged up on by the moving skull – this is sometimes referred to as the coup injury. Shortly thereafter the intracranial content has accelerated to be traveling with the skull, away from the initial impact. As the skull then stops, the brain once again impacts on the internal surface of the skull resulting in damage.
Areas most frequently affected are the inferior surface of the frontal lobes and temporal poles . An unusual form of contrecoup injury is traumatic lens dislocation of the eye .
The term is also less widely used to denote a pattern of injury in the knee: see contrecoup injury of the knee .