Coup-contre-coup mechanism

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Classification according to ICD-10
S06.9 Traumatic brain injury
S06.3 Localized brain injury
ICD-10 online (WHO version 2019)
Mechanism of origin of the "simple" contusion (coup - impact side)
Mechanism of origin of the "contre-coup" (side opposite to the impact)

The coup-contre-coup mechanism ( coup : contusion of the impact side - contre-coup : contusion of the side that is opposite the impact) is the development of brain damage ( cerebral cortical hemorrhage and destruction) or extracerebral hemorrhage both on the side of the impact the human skull , as well as on the opposite side.

Origin of the damage

A light blow ( fr . Coup ) against the head accelerates the skull against the brain, causing the brain to hit the skull at the point of the blow.

If you hit the head harder, the same thing happens, but the brain is also set in motion. If the skull then brakes, either because the maximum possible flexion of the head in relation to the trunk is reached or because the skull hits a solid object (wall, floor, etc.), the brain continues to move due to its inertia and then bounces on the opposite side of the blow ( fr . contre coup ) against the skull. This is the coup-contre-coup mechanism in which the brain is injured first on the list and then with a slight delay on the opposite side facing away from the hit.

Nerve cells are sensitive to pressure. Therefore, the brain in the skull swims in the cerebrospinal fluid ( liquor cerebrospinalis ), which gives the brain buoyancy and keeps it in suspension in the skull. In addition, it is fixed to the skull by the meninges (hard meninges on the skull, spider tissue in the liquor-filled subarachnoid space and soft meninges on the brain). In addition to the spider web skin, the brain water also acts as an impact protection against blows and bumps.

Extent of damage

The extent of brain damage caused by blows to the head depends on the acceleration and braking values ​​that occur. Braking corresponds to negative acceleration .

Most of the time, the extent of the brain damage on the opposite side of the beat is greater than on the actual list. This is due to the fact that the initial acceleration of the skull against the brain is mostly cushioned by tense neck muscles, while the sudden braking of the skull takes place unchecked when the head is maximally flexible or when it hits a solid object. Skull fractures absorb some of the kinetic energy of the blow, which can reduce brain damage. On the other hand, fragments of bone that enter the brain can in turn lead to brain damage.

Classification of damage

Traumatic brain damage is classified according to the extent of the brain damage in

  • slight brain damage with brief loss of consciousness of less than 10 minutes ( traumatic brain injury 1st degree = commotio cerebri )
  • moderate brain damage with long unconsciousness of more than 10 minutes and presumable slight brain contusion ( traumatic brain injury of the 2nd degree = contusio cerebri ) and
  • Severe brain damage with prolonged unconsciousness of more than 10 minutes and secured brain contusion (edema, bleeding, lesions) ( 3rd degree traumatic brain injury = Compressio cerebri )

and according to the type of skull fracture

  • no skull fracture
  • covered skull fracture with intact hard meninges ( dura mater )
  • Open skull fracture with torn hard meninges ( dura mater ) and thus exposed brain

assigned.

localization

In brain contusion, there are typically radiologically detectable foci of contusion both on the side of the causal force and on the opposite side . The most common locations are the frontal and temporal lobes (frontotemporal) as well as the frontal lobes and the brain stem (frontobasal). In the case of brain contusion, however, the more distant, injury-related changes do not necessarily have to occur on the opposite side, which is why the term coup - contre-coup is viewed as outdated and misleading in neurosurgery.

Forensic medical relevance

When a fixed head is hit, the skull fracture (if any) and brain lesion are on the same side. But if a falling head is suddenly slowed down by the impact, a brain lesion is usually also found on the contralateral side. In the case of such delayed trauma caused by a free fall on the back of the head, almost all injuries to the opposite pole (contre-coup contusions) occur.

In traumatic brain damage ( contusio cerebri ) with cerebral cortex contusions , the coup-contre-coup mechanism is of considerable importance, especially for forensic medicine. Indirect foci of contusion of the cerebral cortex are found not only at the point of the force itself ( coup ), but also at the counter- impact point ( contre-coup ). The contre-coup is often crossed: Coup right occipital pole - Contre-coup left frontal pole. Paying attention to the contre-coup injuries to distinguish a blow from a fall on the skull is crucial in the absence of witnesses. The contre-coup is no longer explained as an impact effect of the brain, but rather by the fact that the sudden acceleration that the head experiences during impact creates a negative pressure at the opposite point ( suction theory according to Lenggenhager ). Contre-coup injuries are generally absent when the fixed skull is subjected to force.

The pressure on the point of impact (e.g. back of the head) creates negative pressure at the point of contact ( forehead- temple area). The counter-butt here is in particular the underside of the frontal lobe poles . The suction ( contre-coup ) that occurs can lead to collapses in the orbital roofs. The eyes, as protruding brain parts, are also pulled backwards, which can be seen in the eye socket: The thin medial bony border ( lamina papyracea ) or the basal wall collapses. These orbit signs can be used as an equivalent of the Hirn-Contre-Coup. On impact on the back of the head, the contre-coup injury is generally considerably larger than the coup injury. This is understandable because the brain is more sensitive to suction than to pressure . The situation is different when you fall on your forehead. Here a larger tissue lesion is usually found on the coup side than on the counter-coup pole, because the impact is absorbed by the collapse of the much thinner and elastic bone covering in the frontal area of ​​the skull. Major studies on the subject go back to the former directors of the Institute for Forensic Medicine at Humboldt University ( Charité ), Gunther Geserick and Otto Prokop .

Case study

“A 57-year-old woman was knocked in the chest by a young man after leaving a pub on the street, hit the back of the head on the floor, passed out and died shortly after in hospital. Approximately 10 cm large, longitudinal laceration of the scalp over the rear parts of the right parietal and adjacent occiput. Fracture of the skull in the area of ​​the right posterior fossa . Individual small, partly star-shaped bone fractures in the area of ​​both orbital roofs with slight bending of the fracture ends towards the cranial cavity , on the right side with orbital fat tissue bursting into the fracture lines. Bleeding between the bony skull and the hard meninges in the right posterior fossa and above both roofs of the orbits. Bleeding between the hard and soft meninges over both cerebral lobes and frontal lobes of the cerebral hemispheres as well as over both cerebellar hemispheres, mainly on the right. Mass bleeding in the soft meninges of both cerebellar hemispheres and both frontal lobes of the cerebrum. Numerous foci of cortex fragmentation in the right hemisphere of the cerebellum (coup) and especially in the area of ​​both frontal lobes of the cerebrum (contrecoup). Brain fragmentation with tissue bleeding in the area of ​​the bridge. Swelling of the brain. Right enlargement of the heart. Edema of the lungs . Congestion of blood in the internal organs. Low-grade calcification of the large arteries, their branches and the cerebral vessels. The fractures of the eye socket roofs with the entry of fat from the eye sockets are an impressive confirmation of the mechanics of the creation of the contrecoup ('suction theory' ....). "

- O. Prokop and G. Radam: Atlas of Forensic Medicine. Verlag Volk u. Gesundheit, Berlin, 1987, p. 365.

Individual evidence

  1. ↑ a b c H. Hunger, W. Dürwald and HD Tröger (editor): Lexicon of forensic medicine. Johann Ambrosius Barth, Leipzig, Berlin, Heidelberg, Karl F. Haug Fachbuchverlag Heidelberg, 1993, p. 77. ISBN 3-830-40456-5
  2. ↑ E. Bücheler et al.: Introduction to Radiology. Thieme Verlag, 2006, p. 689. ISBN 3-133-16011-7 restricted preview in the Google book search
  3. ↑ D. Moskop: Neurosurgery. Schattauer Verlag, 2005, p. 334. ISBN 3-794-51991-4 limited preview in the Google book search
  4. ^ B. Knight: Forensic Medicine. ZFA pocket atlas. Hippokrates Verlag Stuttgart, 1986, p. 58. ISBN 3-7773-0796-3
  5. ^ B. Brinkmann and B. Madea: Manual forensic medicine. Volume 1, Springer, Berlin, 2004, p. 401. ISBN 3-540-00259-6 limited preview in the Google book search
  6. ↑ a b O. Prokop and W. Göhler: Forensic Medicine. Verlag Volk u. Health, 3rd ed., Berlin, 1975, p. 194. ISBN 3-437-00192-2
  7. ^ B. Knight: Forensic Medicine. ZFA pocket atlas. Hippokrates Verlag Stuttgart, 1986, p. 56. ISBN 3-7773-0796-3
  8. ^ A b c W. Schwerd (editor): Brief textbook of forensic medicine for doctors and lawyers. Deutscher Ärzte-Verlag, Cologne-Lövenich, 1979, p. 44. ISBN 3-7691-0255-X
  9. ↑ B. Madea et al.: Basiswissen Rechtsmedizin , Springer, 2007, p. 121ff., ISBN 3-540-71428-6 limited preview in the Google book search
  10. ^ G. Geserick, O. Prokop and C. Kruse: Fractures of the bony orbit with blunt head trauma as a contrecoup injury. In: Kriminal Forens Wiss 39, 1980, pp. 53-57.
  11. ^ O. Prokop and W. Göhler: Forensic medicine. Verlag Volk u. Gesundheit, 3rd ed., Berlin, 1975, pp. 194–197. ISBN 3-437-00192-2

literature

  • CB Courville: The mechanism of coup-contrecoup injuries of the brain; a critical review of recent experimental studies in the light of clinical observations. In: Bull Los Angel Neuro Soc 15, 1950, pp. 72-86. PMID 15426860
  • PM Hein and E. Schulz: Contrecoup fractures of the anterior cranial fossae as a consequence of blunt force caused by a fall. In: Acta Neurochirurgica 105, 1990, pp. 24-29. doi : 10.1007 / BF01664853
  • LB Drew and WE Drew: The contrecoup-coup phenomenon: a new understanding of the mechanism of closed head injury. In: Neurocrit Care 1, 2004, pp. 385-390. PMID 16174940
  • G. Szabó: Contributions to the mechanism of contrecoup injuries of the brain. In: International Journal of Legal Medicine 37, 1943, pp. 64-71. doi : 10.1007 / BF01757174