In head injury

Head injury

Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....

, a coup injury occurs under the site of impact with an object, and a contrecoup injury occurs on the side opposite the area that was impacted. Coup and contrecoup injury is associated with cerebral contusion

Cerebral contusion

Cerebral contusion, Latin contusio cerebri, a form of traumatic brain injury, is a bruise of the brain tissue. Like bruises in other tissues, cerebral contusion can be associated with multiple microhemorrhages, small blood vessel leaks into brain tissue. Contusion occurs in 20–30% of severe head...

, a type of traumatic brain injury

Traumatic brain injury

Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...

 in which the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

 is bruise

Bruise

A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...

d. Coup and contrecoup injuries can occur individually or together. When a moving object impacts the stationary head, coup injuries are typical,
while contrecoup injuries are produced when the moving head strikes a stationary object.

In a coup injury, the head stops abruptly and the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

 collides with the inside of the skull

Human skull

The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

.

Coup and contrecoup injuries are considered focal brain injuries

Focal and diffuse brain injury

Focal and diffuse brain injury are ways to classify brain injury: focal injury occurs in a specific location, while diffuse injury occurs over a more widespread area. It is common for both focal and diffuse damage to occur as the result of the same event; many traumatic brain injuries have aspects...

, those that occur in a particular spot in the brain, as opposed to diffuse injuries, which occur over a more widespread area.

The mechanism for the injuries, especially contrecoup injuries, is a subject of much debate. It is likely that inertia

Inertia

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

 is involved in the injuries, e.g. when the brain keeps moving after the skull is stopped by a fixed object or when the brain remains still after the skull is accelerated by an impact with a moving object. Alternately, movement of cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 following a trauma may play a role in the injury.

Mechanisms

The coup injury may be caused when, during an impact, the skull is temporarily bent inward, and impacts the brain. When the skull bends inward, it may set the brain into motion, causing it to collide with the skull opposite side and resulting in a contrecoup injury. The injuries can also be caused by acceleration or deceleration alone, in the absence of an impact. In injuries associated with acceleration or deceleration but with no impact, the brain is thought to bounce off the inside of the skull and hit the opposite side, potentially resulting in both coup and contrecoup injuries. In addition to the skull, the brain may also impact the tentorium

Tentorium cerebelli

The tentorium cerebelli or cerebellar tentorium is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.-Anatomy:...

 to cause a coup injury. Contrecoup injury may be produced by tensile forces.

Cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 (CSF) is also implicated in the mechanism of coup and contrecoup injuries. One explanation for the contrecoup phenomenon is that CSF, which is denser than the brain, rushes to the area of impact during the injury, forcing the brain back into the other side of the skull. If this is the case, the contrecoup impact happens first.

Features

Contrecoup, which may occur in shaken baby syndrome

Shaken baby syndrome

Shaken baby syndrome is a triad of medical symptoms: subdural hematoma, retinal hemorrhage, and brain swelling from which doctors, consistent with current medical understanding, infer child abuse caused by intentional shaking...

 and vehicle accidents, can cause diffuse axonal injury

Diffuse axonal injury

Diffuse axonal injury is one of the most common and devastating types of traumatic brain injury, meaning that damage occurs over a more widespread area than in focal brain injury. DAI, which refers to extensive lesions in white matter tracts, is one of the major causes of unconsciousness and...

. On very rare occasions, contrecoup injury can cause epidural hematoma

Epidural hematoma

Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...

.

Contrecoup contusions are particularly common in the lower part of the frontal lobe

Frontal lobe

The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...

s and the front part of the temporal lobe

Temporal lobe

The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....

s. A 1978 study found that the contrecoup mechanism was responsible for most of the brain lesions such as contusions and hematomas occurring in the temporal lobes of injured individuals. Injuries that occur in body parts other than the brain, such as the lens of the eye

Lens (anatomy)

The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...

, the lung, and the skull and other bones, may also be labelled "contrecoup". The contrecoup mechanism can play a role in pulmonary contusion

Pulmonary contusion

A pulmonary contusion is a contusion of the lung, caused by chest trauma. As a result of damage to capillaries, blood and other fluids accumulate in the lung tissue. The excess fluid interferes with gas exchange, potentially leading to inadequate oxygen levels...

.

History

In the 17th century, Jean Louis Petit

Jean Louis Petit

Jean-Louis Petit was a French surgeon, and the inventor of the tourniquet. He was first enthusiastic about anatomy, received a master's certificate in surgery in Paris in 1700. He became a member of the French Royal Academy of Sciences in 1715, and was named director of the French Royal Academy of...

 described contrecoup injury. In 1766, the French surgeon Antoine Louis

Antoine Louis

Antoine Louis was a French surgeon and physiologist who was born in Metz.He was originally trained in medicine by his father, a surgeon-major at a local military hospital. As a young man he moved to Paris, where he served as gagnant-maîtrise at the Salpêtrière...

 coordinated a meeting of the Académie Royale de Chirurgie on contrecoup injuries, at which papers were to be presented of which one would be chosen to receive the respected prize, the Prix de l'Académie Royale de Chirurgie. The presenter of the chosen paper was not awarded the prize because he failed to make recommended changes. In 1768, the group met again on the topic, and Louis Sebastian Saucerotte won the prize for his paper describing contrecoup injuries in humans and experiments on animals and recommending treatments such as bloodletting

Bloodletting

Bloodletting is the withdrawal of often little quantities of blood from a patient to cure or prevent illness and disease. Bloodletting was based on an ancient system of medicine in which blood and other bodily fluid were considered to be "humors" the proper balance of which maintained health...

 and application of herb

Herb

Except in botanical usage, an herb is "any plant with leaves, seeds, or flowers used for flavoring, food, medicine, or perfume" or "a part of such a plant as used in cooking"...

s to patients' heads.