A coup injury (pronounced “COO”) is a bruise on the brain that forms directly at the site where the head is struck. When a moving object hits a stationary head, the force transfers through the skull and damages the brain tissue immediately beneath the point of impact, causing bleeding, swelling, or both. It’s one of the most common types of traumatic brain injury and often occurs alongside a related injury called a contrecoup, which forms on the opposite side of the brain.
How a Coup Injury Happens
Your brain floats inside your skull, cushioned by cerebrospinal fluid. When something strikes your head, the impact compresses the brain against the inner wall of the skull right at the contact point. This compression tears tiny blood vessels and damages brain tissue, creating a focal contusion, essentially a bruise on the surface of the brain.
The classic scenario for a coup injury is a moving object hitting a stationary head. Think of a baseball striking someone in the temple, or a person being hit by a falling object. The head isn’t necessarily in motion beforehand. The damage concentrates at the exact spot where the force lands. The impact can tear the internal lining of the brain, shear blood vessels, and cause localized swelling that may worsen over the first 24 to 48 hours.
Coup vs. Contrecoup Injuries
These two terms describe where brain damage forms relative to the point of impact, and the distinction matters for diagnosis and treatment.
- Coup injury: Brain damage at the impact site. Typically caused by a moving object striking a stationary head.
- Contrecoup injury: Brain damage on the opposite side of the brain from the impact. Typically caused when a moving head strikes a stationary object, like the ground during a fall.
Both can happen simultaneously. After the initial blow, the brain rebounds inside the skull and slams into the opposite wall, producing a second contusion. The cerebrospinal fluid around the brain actually plays a role here: during impact, this denser fluid shifts toward the point of contact, pushing the less dense brain tissue in the opposite direction and driving it into the far side of the skull. One notable finding is that contrecoup injuries tend to be more severe than coup injuries, likely because the brain strikes bony ridges inside the skull as it rebounds.
Common Causes
Road traffic accidents are the leading cause, accounting for more than 60% of cases in some studies. Motorcycle and scooter riders are especially vulnerable, including passengers. Falls are the second most common cause, followed by assaults and other blunt-force impacts. Sports collisions, workplace accidents, and any scenario where an object strikes the head can produce a coup injury.
Symptoms to Recognize
Because a coup injury damages a specific area of the brain, the symptoms depend heavily on which part was hit. A blow to the front of the head may affect decision-making, personality, or impulse control. An impact to the side could disrupt speech or spatial awareness. An injury to the back of the head might cause vision problems.
General symptoms that overlap across all locations include headache, confusion, dizziness, nausea, and difficulty concentrating. More severe coup injuries can cause loss of consciousness, slurred speech, weakness on one side of the body, seizures, or clear fluid draining from the nose or ears. Symptoms don’t always appear immediately. Bleeding and swelling can build over hours, so someone who seems fine right after a blow to the head may deteriorate later.
How Coup Injuries Are Diagnosed
CT scans are the first-line tool in emergency settings because they’re fast, widely available, and good at detecting bleeding inside the skull. On a CT scan, a coup contusion may initially appear as a darker area of swelling at the impact site, sometimes with bright spots indicating blood. Doctors often repeat CT scans over time because contusions can grow as hemorrhage increases in the hours after injury.
MRI is more sensitive than CT for detecting smaller contusions and for mapping the full extent of swelling and bleeding. It’s typically used when someone has neurological symptoms that seem worse than what the CT shows, or when symptoms persist but the initial scan looked normal. MRI is also better at distinguishing between fresh and older bleeding, which helps doctors understand the injury’s progression.
Severity is graded using the Glasgow Coma Scale, which scores a person’s eye opening, verbal responses, and physical movement on a scale of 3 to 15. A score of 13 to 15 indicates a mild traumatic brain injury (concussion), 9 to 12 is moderate, and 3 to 8 is severe.
What the Damage Looks Like Inside the Brain
Nearly all brain contusions involve some degree of hemorrhage. At the coup site, the impact tears small blood vessels in the cortex and the tissue just beneath it, producing bleeding that can range from microscopic to large enough to require surgical intervention. Swelling surrounds the bleeding area and can compress nearby healthy tissue.
In addition to the localized bruise, the jarring force can cause diffuse axonal injury, where the long connecting fibers between brain cells stretch and tear. This type of damage is harder to see on imaging but can have significant effects on thinking, coordination, and consciousness. A coup injury can also cause traumatic subarachnoid hemorrhage, where blood leaks into the thin space surrounding the brain’s surface at the impact site.
Recovery and What Affects It
Mild coup injuries, where the contusion is small and there’s no significant bleeding, often resolve over weeks to a few months with rest and gradual return to activity. Headaches, fatigue, and difficulty concentrating may linger during this period but typically improve.
Moderate to severe injuries follow a much less predictable path. Swelling can peak two to three days after the initial injury, and this secondary swelling is sometimes more dangerous than the original contusion. How well someone recovers depends on the size and location of the contusion, whether there’s bleeding that puts pressure on the brain, the person’s age, and whether there were injuries on both the coup and contrecoup sides. Dual-site injuries carry a worse prognosis because the brain is damaged in two places simultaneously.
Rehabilitation for more significant injuries often involves physical therapy, occupational therapy, and cognitive rehabilitation to retrain skills affected by the damaged brain region. Some people recover fully. Others experience lasting changes in memory, mood, or physical function, particularly when the contusion was large or located in areas critical for language or movement.