Contrecoup injuries are fairly common after falls or car accidents in Illinois. A contrecoup is a particular type of injury to the brain. According to the National Center for Biotechnology Information, the result of a contrecoup injury is focal, meaning that it only affects a specific area of the brain. This distinguishes it from edema or diffuse axonal injury, both of which affect all or most of the brain tissues at once. 

A contrecoup injury results from a blow to the head and causes bruising of the brain, also called a contusion. However, the bruising takes place not in the area where the impact occurred but in a different area of the brain. There are several different theories regarding what specifically causes a contrecoup injury. Johns Hopkins Medicine theorizes that the force of the blow causes the brain to move within the skull and strike against the hard surface on the other side. The resulting damage to the blood vessels and internal tissues causes the contrecoup lesion to form. 

Contrecoup injuries usually occur when the head strikes against a stationary object while in motion. They occur more frequently with impact to the side or the back of the head. Older adults and young men are more likely to experience contrecoup injuries. 

In addition to the damage to brain tissues and blood vessels, a contrecoup injury may cause tearing of the internal lining between the brain and the skull. Brain swelling can develop as well as bruising and bleeding. When visual abnormalities occur following minor head trauma, a contrecoup injury may be responsible.