A coup injury is the result of a sudden, violent stop that causes the brain to accelerate forward and hit the side of the skull. A contracoup injury, on the other hand, occurs when the brain accelerates forward, hits the side of the skull, and then bounces off the other side of the skull. In both cases, the brain is damaged as it rubs against the inner ridges of the skull.
A coup injury will present a contusion at the site of impact. A contracoup injury, on the other hand, will present a contusion on the opposite site of impact. A brain that undergoes a particularly violent and sudden impact can experience a coup and contracoup injury simultaneously.
A coup injury is usually the result of an object striking the head, while a contracoup injury is often the result of the head striking an object. Common causes of coup and contracoup injury include:
The degree and rate of recovery for coup and contracoup injuries depend upon the severity of the injury, as well as upon other individual circumstances. Minor coup and contracoup injuries may easily resolve without long-term effects, while patients with severe coup and contracoup will have a more guarded prognosis. In all cases, the amount of time spent unconscious or in a coma, as well as how much is recovered within the first month, are good indicators of long-term recovery.