What do you call an injury when the damage occurs to the side under the impact and the opposite side?

A coup-countrecoup brain injury occurs when there is significant impact to the brain that causes the brain or skull to slam into the opposite side of the site of impact. The result is damage at the impact site, as well as on the opposite side of the brain. Though any injury can cause a coup-contrecoup brain injury, these incidents are often especially violent, producing immediate symptoms. Serious car accidents, blows to the head, forceful falls, and acts of violence are particularly adept at producing these injuries.

Because coup-contrecoup brain injuries require significant impact, the symptoms are often severe, and survivors may need extensive support to recover. The specific prognosis, though, depends on the location of the impact, the severity of the blow, overall brain health, age, and other personal factors.

Concussion

A concussion, sometimes called a mild traumatic brain injury (mTBI), is the most common type of brain injury, accounting for hundreds of thousands of emergency room visits each year. Commonly caused by a sudden blow to the head, a concussion jolts your brain, causing the brain to accelerate in the direction of the force. In other words, a concussion shakes your brain.

Concussions range from mild to quite severe. A generation ago, most doctors believed that concussions were little more than inconveniences. We now know that a concussion can cause life long damage. People who suffer multiple concussions may experience concussion-related syndromes.

People who suffer frequent concussions may develop a condition called chronic traumatic encephalopathy. Especially common among professional football players, this form of brain damage can permanently change mood, behavior, and brain function.

Brain Contusion

A contusion is simply a bruise—a mild form of bleeding under the skin. Brain contusions are similar to concussions, and often occur in conjunction with them. If a brain contusion does not stop bleeding on its own, it may need to be surgically removed. The extent of damage associated with a brain contusion depends on the size of the bleed, the length of time it lasts, the effects of surgery, and the location of the injury.

Diffuse Axonal Injury

A diffuse axonal injury (DAI) is similar to a concussion in that it results from the brain moving, but much more serious. With a DAI, the head so violently moves that the brain stem cannot keep up with the rate of movement, causing tears in the connections of the brain. These tears can be microscopic, producing varying degrees of brain damage. They can also be quite large. Tears that are sufficiently large can be fatal.

The severity of symptoms with this type of injury is largely dependent on the brain areas affected, the severity of the tears, and whether any other injuries—such as a contusion or concussion—were also sustained.

Second Impact Syndrome

Just as a scab that is reopened takes longer to heal and may produce a scar, a second brain injury when you've already sustained a first can cause more catastrophic damage. Sometimes called a recurrent traumatic brain injury, the effect of second impact syndrome depends on the location of the injury, the severity of the first injury, and the degree of trauma sustained.

A second impact is more likely to cause severe brain damage than a first, even if the victim does not lose consciousness. If you suffer a blow to the head in the months following a brain injury, seek prompt medical care, even if you feel fine.

Shaken Baby Syndrome

Shaken baby syndrome is similar to diffuse axonal injury, but tends to produce more global effects. Now considered a form of criminal child abuse in most places, it often results from parents' frustration with incessant crying. Shaken babies often suffer broken blood vessels and brain hemorrhages, strokes, and tears in the brain and brain stem. In many cases, shaken babies die. The effects are almost always catastrophic and long-lasting.

Penetrating Injury

A penetrating injury occurs when an object penetrates the skull and brain. These injuries can be fatal if not promptly treated, because they often cause severe bleeding, blood clots, disrupted oxygen supply to various brain regions, and other immediate side effects.

Removing the object that penetrated the skull may worsen the bleeding or further damage the brain, so never remove an object lodged in the skull. You and your doctor will have to assess whether the benefits of removal and surgery outweigh the risks. In many cases, doctors opt to leave small objects—such as bullets or pellets—in place. Bullets are the leading cause of penetrating brain injuries, killing 91% of the people they affect.

Through-and-through injuries occur when an object enters the brain and exits at another location. These penetrative injuries tend to cause damage in multiple locations, as well as catastrophic bleeding. Additionally, some objects ricochet within the skull prior to exiting, causing even more significant damage.

People who survive penetrating injuries may need repeated brain surgeries, high doses of antibiotics, and an assortment of therapies designed to restore function. Ultimately, the degree of disability and the prognosis depend on the location of the injury, its severity, whether there was a brain bleed, and similar factors.

Primary injury occurs at the moment of initial trauma, including

• skull fracture (breaking of the bony skull),
• contusions (bruise/bleed on the brain) that can lead to hematomas (blood clots in the meningeal layers or in the cortical/subcortical structures as a result of the trauma),
• concussions (low velocity injury resulting in functional deficits without pathological injury),
• lacerations (tears in brain tissue or blood vessels of the brain),
• diffuse axonal injury (traumatic shearing forces leading to tearing of nerve fibers in the white matter tracts).

Primary injuries can be caused by either a penetrating (open-head) injury or a nonpenetrating (closed-head) injury.

A penetrating (open-head) injury involves an open wound to the head from a foreign object (e.g., bullet). It is typically marked by focal damage that occurs along the route the object has traveled in the brain that includes fractured/perforated skull, torn meninges, and damage to the brain tissue (Hegde, 2006).

A nonpenetrating (closed-head) injury is marked by brain damage due to indirect impact without the entry of any foreign object into the brain. The skull may or may not be damaged, but there is no penetration of the meninges. Nonpenetrating injuries can be of two types:

• Acceleration injuries-caused by movement of the brain within the unrestrained head (e.g. whiplash injury). If the force impacting the head is strong enough, it can cause a contusion at the site of impact and the opposite side of the skull, causing an additional contusion (coup-contrecoup injury).
• Non-acceleration injuries-caused by injury to a restrained head and, therefore, no acceleration or deceleration of the brain occurs within the skull (e.g., blow to the head). These usually result in deformation (fracture) of the skull, causing focal localized damage to the meninges and brain.

Secondary Injury

Secondary injury occurs as an indirect result of the insult. It results from processes initiated by the initial trauma and typically evolves over time. These include

• ischemia (insufficient blood flow);
• hypoxia (insufficient oxygen in the brain);
• hypo/hypertension (low/high blood pressure);
• cerebral edema (swelling of the brain);
• raised intracranial pressure (increased pressure within the skull), which can lead to herniation (parts of the brain are displaced);
• hypercapnia (excessive carbon dioxide levels in the blood);
• meningitis (infection of the meningeal layers) and brain abscess;
• biochemical changes (changes in levels of neurotransmitters, sodium, potassium, etc.);
• epilepsy.

References

Hegde, M. N. (2006). A coursebook on aphasia and other neurogenic language disorders (3rd ed.). Clifton Park, NY: Delmar Cengage Learning.

In addition to the severity of a brain injury, the type of injury can make a difference in a person’s recovery.

For instance, focal and penetrating injuries tend to injure specific portions of the brain. A person with this type of injury may have less overall damage as a result, depending on where the injury occurs and the cognitive processes involved in the damaged area of the brain. In contrast, a person whose head hits the pavement after a fall may injure both the area of the brain at the point of impact and the opposite side of the brain as well. This is called a coup-contrecoup injury. This type of injury may become diffuse because of the shearing and tearing that can occur as the brain moves back and forth within the skull.

Other possible types of damage include contusions or bruises that result in swelling. Rotation injuries also result in shearing and tearing of brain tissue. When a baby is shaken, the brain often has several types of injuries including coup contra coup, rotation injuries and swelling. In this, as well as similar injuries to older children, the blood vessels tear causing internal hemorrhaging in addition to the direct damage to the brain tissue.

Most brain injuries are compised of a mix of both primary and secondary injuries. The more severe the initial insult, the more likely the secondary injuries will have a major effects on the person's overall outcome

Primary Injury

Primary injuries include the injuries that are sustained at the time of the traumatic event, such as:

Intracranial Hemotomas

Intracranial hematomas are the rupture of a blood vessel leading to the collection of blood in brain tissues or empty spaces. There are several types of hematoma:

• Epidural Hematoma: A blood clot outside of the brain and the dura but under the skull.
• Subdural Hematoma: A blood clot between the brain and the dura.
• Subarachnoid Hemorrhage: Bleeding withing the layers of the dura, specifically under the aracnoid layer.
• Intracerebral Hematoma: Bleeding within the brain tissue itself caused by the rupture of a blood vessel within the brain.
• Intraventricular Hemorrhage: Bleeding into the ventricles of the brain

Skull Fractures

Skull fractures are a concern because a disruption in the skill can cause injury to the brain or provide an open avenue for infection or both.

• A linear skull fracture is a break in the skull resembling a thin line or crack. These unjuries are usually moitored and not treated sugically.
• A depressed skull fracture is a break in or crushing of part of the skull. These types of skull fractures may require elevation of the skull through craniotomy to prevent increased pressure on the brain.
• A basilar skull fracture occurs at the base of the brain and can cause leakage of cerebral spinal fluid.

Contusions/Coup-Countrecoup

A contusion, or a coup-contrecoup injury, is a bruise of the brain tissue. With this type of injury, flexion-extension or acceleration-deceleration results in the formation of a linear, anterior-posterior lesion at the point of impact. Injuries can also be lateral or side-to-side. This is the type of injury that occurs in a motor vehicle crash, where the head is propelled forward and accelerated and then moved back in deceleration.

Diffuse Axonal Injury (DAI)

Diffuse axonal injury or DAI usually results from rotational forces or violent stopping.Unlike brain trauma that occurs due to a direct blow, DAI is the reult of twisting and tearing of the connections between the cells of the brain.

Secondary Injury

Secondary brain injury results fro metabolic and physiologic changes that bedin at the time of the initial injury and may last for hours and days, such as:

• Hypoxia and Hypotensions
• Ischemia
• Cerebral Edema - resulting in increased intracranial pressure
• Hydrocephalus
• Second Impact Syndrome - an extremely rare outcome where death or severe neuroloic injury occurs when a person sustains a scond concussion before symptoms from an earlier one have subsided.

Penetrating vs. Closed BInjury

Traumatic brain injury (TBI) is commoly catorized as penetrating or closed.

Pentrating TBI: An injury in which the dura, the outer latyer od the meninges, is compromised. Penetrating injuries can be caused by high velocity projectiles (such as bullets and fragments) or objects of lower velocity (such as knives or bone fragments). Only 1-2% of TBIs are penetrating head injuries. Closed TBI: An injury in which the dura remains intact. It is further classifies as mild, moderate and severe. Mild TBI is also know as concussion.

Most brain injuries are comprised of a mix of both primary and secondary injuries.

The more severe the initial iinsult, the more likely the secondary injuries will have a moajor effect on the person's overall outcome.