A coup injury to the brain occurs at the site of pri- mary impact, when deformation of the skull con- tacts the underlying brain. The site of scalp injury will generally approximate the site of brain injury.
Such a coup injury to the brain is usually repre- sented by localized subarachnoid haemorrhage and cortical surface contusion with, or without, laceration.
In a ‘moving head injury’, such as might be expe- rienced following a fall onto the back of the head, for example, impact causes the skull to stop moving suddenly, while movement of the brain continues momentarily before also stopping. As a conse- quence of such relative movement, and the effects of deceleration forces acting on the skull and the cranial contents, a distinctive pattern of head/brain injury can be recognized (Figure 9.11).
The site of impact is characterized by contact injuries to the scalp (bruising, abrasion and lac- eration, for example), skull (linear or depressed fractures) and sometimes cerebral contusion, although these are less commonly seen when the impact site is on the back of the head. Intracranial bleeding, particularly subdural and subarachnoid haemorrhage may be present and, of particular significance in interpreting the nature of the head injury, there are frequently cerebral contusions at sites distant from the primary impact. Such inju- ries, called contrecoup contusions, are most com- monly seen on the under-surfaces of the frontal and temporal lobes following a fall onto the back of the head (Figure 9.12). The precise mechanism by which they are caused remains controversial, suggestions being that they represent the effects of contact against the irregular surfaces of the anter- ior and middle cranial fossae, or perhaps the effect of differential pressures within the brain following deceleration.
A careful evaluation of the pattern of head/brain injury is particularly important when a distinction is to be made between injuries in keeping with a fall
Figure 9.10 Microscopy of axonal injury. The immunohistochemical staining of β-amyloid precursor protein (β-APP) demonstrates axonal injury in white matter (corpus callosum). Discrete axonal swellings and ‘axonal retraction bulbs’ can be visualized following traumatic brain injury if the injured person survived for some hours after sustaining their head injury.
N eck injuries
versus assault; a head that is struck, while in contact with the ground and not moving, will not generally be accompanied by contrecoup cerebral injuries.
For reasons that are not altogether clear, but which may reflect the relative smoothness of the inner surface of the posterior cranial fossae, falls onto the front of the head are rarely accompanied by contrecoup contusions of the occipital lobes
or cerebellar hemispheres. Therefore, a definitive opinion regarding the nature of head/brain injuries in a difficult case will require close clinico pathological correlation, and an evaluation of witness evidence.
■ Neck injuries
The neck is the site of many different types of injury, some minor, some completely incapacitat- ing. Its relevance in forensic medicine results from the presence of a large number of vital structures – the upper respiratory and gastrointestinal tracts, major blood vessels, major nerve trunks, the ver- tebral column and the spinal cord. It is particu- larly prone to injury as a consequence of assault or accidents as it can be grasped easily and the weight of the head means that rapid movement of the head on the neck (e.g. sudden deceleration in a road traffic collision) can result in substan- tial trauma. Protection of the integrity of the neck in the living, following traumatic insults likely to have injured it, is imperative prior to clinical and radiological assessment. Layered, dissection of the anterior (and often posterior) neck structures is an integral part of the forensic post-mortem examination.
Scalp injury (fracture) brain damage
(a)
May suffer secondary fracture
Temporal and frontal contusion
Scalp injury (fracture) (b)
Figure 9.11 Example of sclerotic representation of the formation of coup and contrecoup brain injury. (a) Impact to the non-moving head causing coup injuries, and (b) a fall onto the back of the head – a ‘moving head injury’ – causing contrecoup injuries.
Figure 9.12 Contrecoup contusions on the under-surface of the brain.
9 R e gional injurie s
Penetrating trauma – sharp force or ballistic – to the neck has the potential to injure a variety of complex structures and requires careful evaluation in the living as well as at post-mortem examina- tion. Of particular forensic significance in incised wounds to the neck is the pattern of injury (self- inflicted versus assault), the presence of arte- rial injury capable of explaining ‘arterial spray’ in blood-staining at the scene of a suspicious death and venous injury raising the possibility of death having been caused by cardiac air embolism.
The application of pressure to the neck, whether it be manual or by means of a ligature, and the pat- tern of injury seen in such a scenario, is considered in more detail in Chapter 15, p. 152.
■ Spinal injuries
The spine is a complex structure with interlock- ing but mobile components. It is designed to flex to a great extent but lateral movement and extension are much more limited. The spine is very commonly injured in major trauma such as road traffic accidents or falls from a height, and severe injury with discontinuity is easily identi- fied. However, sometimes the spinal injuries are more subtle and it is only after careful dissection that damage to the upper cervical spine and, in particular, disruption of the atlanto-occipital joint will be revealed.
For the survivors of trauma, spinal injuries may have some of the most crucial long-term effects because the spinal cord is contained within the spinal canal and there is little, if any, room for movement of the canal before the cord is dam- aged. The sequelae of spinal damage will depend upon the exact anatomical site and mechanism of injury.
The type of injury to the spine will depend upon the degree of force and the angle at which the spine is struck. A column is extremely strong in compres- sion and, unless the force applied is so severe that the base of the skull is fractured, vertically applied forces will generally result in little damage if the spine is straight. Angulation of the spine will alter the transmission of force and will make the spine much more susceptible to injury, particularly at the site of the angulation.
Force applied to the spine may result in damage to the discs or to the vertebral bodies. The other
major components of the vertebrae – the neural arches and the transverse processes – are more likely to be injured if the force of the trauma is not aligned with the spine.
Whiplash injuries associated with road traf- fic fatalities are very common and are caused by hyperextension of the neck; hyperflexion is less likely to cause damage. Hyperflexion injuries can be caused if heavy weights are dropped onto the back of a crouching individual; this scenario may be seen in roof falls in the mining industry. Hyper- flexion injuries are also seen in sports – particu- larly rugby scrums and diving. Such injuries can cause fatalities or substantial disability such as quadriplegia.
Forceful extension of the spine can be seen, although rarely now, in the cervical injuries associ- ated with judicial hanging where there is a long drop before the sudden arrest and forceful exten- sion of the neck. Forceful flexion of the spine will commonly lead to the ‘wedge’ fracture or com- pression of the anterior aspect of a vertebral body (Figure 9.13). Lateral forces will lead to fracture dis- locations where one vertebral body passes across its neighbour; this displacement will seriously compromise the integrity of the vertebral canal.
Damage to the intervertebral discs can occur as a solitary lesion or it may be part of a more complex spinal injury.
Figure 9.13 Crushed vertebral body as a result of a hyperfl exion injury.
Chest injuries
■ Chest injuries
The chest can be subject to all kinds of injury and is particularly susceptible to both blunt and penetrat- ing injuries.
Adequate respiration requires freedom of move- ment of the chest, functioning musculature and integrity of the chest wall. Any injury that impairs or prevents any of these activities will result in a reduction in the ability to breathe, which may result in asphyxiation. External pressure on the chest may result in traumatic asphyxia by restricting move- ment; this may occur during road traffic collisions or following collapse of structures such as mine tunnels, or buildings in earthquakes. Pressure on the chest that restricts movement may also occur if the individual simply gets into, or is placed into, a position in which the free movement of the chest is restricted. This positional asphyxia occurs most commonly in individuals that are rendered im mobile through alcohol or drugs and may be seen follow- ing restraint in custodial settings; it may also be seen in the healthy, for example, attempting to climb through a small window to gain access to a property.
Blunt injury may result in fractures of the ribs. The fracture of a few ribs is unlikely to have much effect, other than causing pain, in a fit adult. In an individ- ual with respiratory disease (e.g. chronic obstructive pulmonary disease) there are greater risks for the development of respiratory compromise or infection.
If there are numerous rib fractures, and particularly if they are in adjacent ribs, the functional integrity of the chest wall may be compromised, limiting res- piratory capabilities even in fit individuals. Multiple rib fractures may result in the so-called ‘flail’ chest and, clinically, the area of chest around the frac- tures may be seen to move inwards on inspiration – paradoxical respiration (Figure 9.14). The clinical effects of such injuries depend on their extent and on the respiratory reserve of the individual: an eld- erly man with chronic lung disease may be tipped into terminal respiratory failure by injuries that would only be a painful irritant to a fit young man.
Trauma that has fractured left sided 10th, 11th and 12th ribs may be substantial enough to cause injury to the underlying spleen.
Rib fractures may have other more serious con- sequences. If the sharp ends of the fractured bones are driven inwards, they may penetrate the under- lying pleural lining of the chest wall cavity, or even
the underlying lung itself, resulting in a pneumo- thorax. If subcostal, or pulmonary, blood vessels are also injured, the resulting haemorrhage associated with the leakage of air will produce a haemo- pneumothorax. Pneumothoraces may also develop if fractured rib margins are forced outwards through the skin.
Children are, in general, more resilient and better able to cope with rib fractures. However, rib fractures in children have a particular place in forensic medicine, as they can be a marker for non-accidental injury (see Chapter 7, p. 71 and Chapter 13, p. 137).
Rib (and sternal) fractures in adults are frequently identified at post-mortem examination following cardiopulmonary resuscitation (CPR) or cardiac mas- sage. They are usually located anteriorly, or later- ally, and involve those ribs underlying the regions that experience most compression during CPR. They are frequently symmetrical and, if there has been no survival following CPR attempts, they lack associated haemorrhage. Posterior rib fractures, or fractures of
(a)
Figure 9.14 Multiple rib fractures (a) following a road traffi c collision. There were many ‘fl ail’ segments and fractured rib ends pierced the underlying lung (b).
(b)
9 R e gional injurie s
the first rib, for example would be unusual as a con- sequence of CPR. The nature of rib fractures, thought to be related to CPR may become the subject of argu- ment in court and, in an individual with a history of chest trauma, who subsequently receives CPR attempts, microscopic examination of rib fractures identified at post-mortem examination – for evidence of ‘healing changes’ – may be of assistance.
Penetrating injuries of the chest, whether caused by sharp-force trauma (stab wounds) or gunshot wounds, may result in damage to any of the organs or vessels within the thoracic cavities. The effect of the penetration will depend mainly upon which organ(s) or vessel(s) are injured. Penetration of the chest wall can lead to the development of pneumothorax, haemothorax or a combination (haemo-pneumothorax).
Injury to the lungs will also result in the develop- ment of pneumothoraces, and damage to the blood vessels will result in haemorrhage, which may be confined to the soft tissues of the mediastinum or enter the pleural cavities. Haemorrhage from pen- etrating injuries to the chest may remain concealed with little external evidence of bleeding and it is not unusual to find several litres of blood within the chest cavity at post-mortem examination. Follow- ing penetrating chest injury, and when an injured person is capable of purposeful movements follow- ing infliction of such an injury, external blood loss may not be apparent at the locus of infliction of that injury, resulting in potential difficulties in the interpretation of the scene of an alleged assault.
It follows that the lack of any evidence of external bleeding at such a scene does not imply that inflic- tion of the – subsequently fatal – injury could not have occurred at that locus. The answer to the ques- tion commonly asked in court, ‘Would you not have expected immediate bleeding from such a serious injury’, must be ‘Not necessarily’.
■ Abdomen
The anatomy of the abdominal cavity plays a major role in determining the type of injuries that are found. The vertebral column forms a strong, midline, vertical structure posteriorly, and blunt trauma, especially in the anterior/posterior direc- tion, may result in compression of the organs lying in the midline against the vertebral column. This compressive injury may result in substantial blunt
force injury to intra-abdominal organs, including bruising (or even transection) of the duodenum or jejunum, rupture of the pancreas, rupture of the liver, and disruption of omentum and mesentery (Figures 9.15 and 9.16).
The forces required to cause these injuries in an adult must be considered to be severe and they are commonly encountered in road traffic collisions. In an otherwise healthy adult, it would be unusual for a simple punch to the abdomen to cause significant intra-abdominal injuries, but kicks and stamps are commonly the cause of major trauma. The kidneys and the spleen are attached only by their hila and are susceptible not only to direct trauma but also to rotational forces that may result in avulsion from their vascular pedicles. Blunt trauma to the spleen is sometimes associated with delayed rupture leading to haemorrhage and possibly death some hours or even days after the injury. Pancreatic trauma may
Figure 9.15 Mesenteric bruising and laceration following blunt force trauma in a road traffi c collision.
Figure 9.16 Multiple lacerations of the liver following blunt force abdominal trauma in a road traffi c collision.
F urther information sourc es
lead to the development of a pseudocyst, with little or no short-term or long-term sequelae. Once diag- nosed the successful treatment of these conditions may be conservative or surgical.
Abdominal injuries in children may have the same causes, but the forces required to cause them will be considerably reduced, and the slower compressive forces associated with squeezing of the abdomen during abuse may also result in the injuries described above. The possibility of intra- abdominal injuries being caused by CPR is also one that is raised in court, but such instances of injury to either solid or hollow intra-abdominal organs in adults or children are very rare.
Penetrating injuries to the abdomen can be the result of either gunshots or sharp-force trauma. The effects of these injuries will depend almost entirely on the organs and vessels involved in the wound track. A penetrating injury to the aorta, or infe- rior vena cava, can result in severe haemorrhage and may produce rapid death. Peritonitis from a ruptured bowel or stomach may not be recognized until too late, by which time overwhelming septicaemia will have developed. The presence of peritonitis and blood clots at post-mortem are both factors which may give indications of how long before death intra-abdominal trauma had occurred.
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