contrecoup

Contrecoup is a term used in neurology and neurosurgery to describe a type of traumatic brain injury where damage occurs on the side of the brain opposite to the site of impact. The term comes from French, meaning "opposite blow." It commonly accompanies coup injuries, which occur at the site of impact.

Mechanism and pattern: after a blunt head impact, the brain moves within the rigid skull due to inertia. This movement can cause the brain to strike the inner skull on the side opposite the initial impact, leading to contusions, hemorrhages, or other brain injuries. Contrecoup injuries are more likely with high-velocity forces and can be influenced by factors such as brain atrophy, skull shape, and vascular vulnerability.

Clinical features: the presentation varies with the extent of injury and may include headache, confusion, memory problems, focal weakness, seizures, or loss of consciousness. Diagnosis is based on clinical suspicion and imaging studies, with computed tomography (CT) or magnetic resonance imaging (MRI) revealing contusions or hemorrhages at the contralateral site.

Management: treatment depends on severity. Some cases are managed conservatively with observation, rest, and symptom control, while others require neurosurgical intervention for complications such as mass effect, intracranial hemorrhage, or raised intracranial pressure. Rehabilitation may be necessary for cognitive or motor deficits.

Prognosis: outcomes vary widely and depend on the overall extent of brain injury, associated injuries, and timeliness of treatment. Some patients recover fully, while others experience persistent neurologic deficits.

See also: coup injury, traumatic brain injury, diffuse axonal injury.