Coup contrecoup injury

As a coup - contre -coup mechanism ( coup contusion of the impact side - Contre -coup: contusion of the side that is opposite the impact) refers to the development of brain damage ( cerebral cortex contusion bleeding and destructions ) or extracerebral bleeding both on the side of trauma to the human skull, and on the opposite side.

Formation

If no fracture occurs, the forces acting on the skull mechanical forces (movement energy ) are taken up only a small part of the direct impingement. The entire head ( including the brain ) is therefore exposed to a strong acceleration in the short term. Due to the resulting forces occurs by the onset of rapid acceleration to deformations of the brain structures and redistribution of CSF. In the brain occur under this deformation by the inertia of the brain mass (and the related different pressure conditions in the soft brain matter ) shear forces as a cause of structural lesions ( so-called contusion ) both on the crash side and on the impact opposite side.

Reimann and colleagues illustrate this using the example of the 1990 straight If a stone into the water: The linear case of the stone in the depth corresponds to the direction of impact; the lateral wave propagation on the surface corresponds to the spatial distance effect.

Localization

In the brain contusion, there are typically both on the side of the causative force as well as on the opposite radiologically visible contusion. The most common sites are the frontal and temporal lobes ( frontotemporal ) and the frontal lobes and the brain stem ( frontobasal ). In the case of a brain contusion, however, the more remote injury-related changes do not necessarily occur on the opposite side, which is why the term Coup - Contre -coup is considered in neurosurgery as outdated and misleading.

Medical-legal relevance

When it is beaten to a fixed head, skull fracture are ( if any) and brain lesion on the same side. However, if a falling head suddenly slowed by the impact, a brain lesion is usually present on the contralateral side. In such a delay trauma by free fall on the back of the head even almost only Gegenpolverletzungen arise ( contre -coup - contusions ).

When traumatic brain damage ( cerebral contusion ) with cortical contusion foci is the coup - contre -coup mechanism especially for the forensic pathologist of considerable importance. Not only at the site of trauma itself ( coup ), but propagated to the opposite joint ( contre -coup ), there are indirect contusion foci of the cerebral cortex. Often the contre -coup is crossed: Coup right occipital pole - Contre -coup left Stirnpol. Observance of Contre -coup injuries to distinguish a shock from a fall on the head is of paramount importance when there are no witnesses. The Contre -coup is declared no longer as an impact effect of the brain, but by the fact that in the sudden acceleration experienced by the head upon impact, at the opposite point, a negative pressure (suction - theory Lenggenhager ) arises. Contre -coup injuries are missing namely generally in violence against the fixed skull.

The pressure on the point of impact (eg, back of the head ) generates a vacuum on the opposite joint ( frontal temporal area). The breakout point is especially the underside of the frontal lobe poles. Due to the occurring suction ( contre -coup ) there may be irregularities of the orbital roofs. The eyes also as a pre- invaginated parts of the brain are pulled backwards, which can be seen in the orbit: The thin medial bony limitation (lamina papyracea ) or the basal wall collapses. This Orbitazeichen can be used as an expertise equivalent of the brain - contre - coup. Upon impact on the mind, the contre -coup injury is formed generally considerably larger than the coup injury. This is understandable, because the brain is more sensitive as compared to pull against pressure. The conditions are different in the fall on the forehead. Here is mostly on the coup - page a greater tissue lesions found as the Contre -coup - pole, because the shock is absorbed by the collapse of the much thinner and elastic bone coverage in the frontal area of ​​the skull. Major studies on the subject go back to the former directors of the Institute of Legal Medicine, Humboldt University ( Charité), Gunther Geserick and Otto Prokop.

Case Study

" A 57 years old woman was pushed after leaving a restaurant on the street by a young man on the chest, hit his head on the ground, lost consciousness and died shortly afterwards in hospital. About 10 cm wide, longitudinal laceration of the scalp over the posterior parts of the right parietal and adjacent occipital bone. Schädelberstungsbruch in the area of ​​the right posterior fossa. Some small, some star-shaped fractures in the area of ​​both orbital roofs with low bending of the broken ends to the back skull cave, right side with Einsprengung of orbital adipose tissue in the fracture lines. Bleeding between the bony skull and dura mater in the right posterior fossa and two orbital roofs. Bleeding between hard and soft meninges over the brain's two main and frontal lobes of the cerebral hemispheres as well as the two halves of the cerebellum, predominantly right. Massive bleeding into the soft meninges of both the cerebellum and both halves of the frontal lobe of the cerebrum. Numerous cattle herd fragmentation in the right half of the cerebellum ( coup ) and particularly in the region of both frontal lobes of the cerebrum ( contrecoup ). Brain destruction with Gewebsblutungen in the area of the bridge. Swelling of the brain. Right enlargement of the heart. Edema of the lungs. Congestion of internal organs. Mild atherosclerosis of the large aorta, its outgoing branches and the basic brain vessels. The fractures of the orbital roofs with occurrence of fat from the eye sockets are an impressive confirmation of the mechanism of the formation of the Contrecoup ( ' Sogtheorie ' ....). "