Accidents and poisoning

Head injury

Head injury is the commonest cause of death in injured children. Severity of the injury is therefore the principal determinant of outcome in multisystem trauma. In young children, falls are the commonest cause of severe injury, whereas in the older age groups, road traffic collisions, particularly from cycle accidents, are more common. Non-accidental (inflicted) head injury must be considered in infants.

Damage to the central nervous system (CNS) as a result of head injury can be divided into primary and secondary causes ( Table 7.2 ).

Primary injury

This is sustained as a direct consequence of the impact, causing disruption of the intracranial contents, including neuronal injury, such as diffuse axonal injury and vascular trauma.

Diffuse axonal injury (DAI) is one of the most serious forms of primary neuronal injury and is associated with high mortality and neurodisability. It results in widespread injury in the brain, not in just one specific area, and occurs as a result of traumatic shearing forces due to rapid acceleration, deceleration and/or rotation of the brain ( Fig. 7.2 ). As the brain moves rapidly backwards and forwards within the skull, the axons are disrupted, particularly at the grey–white matter junction. The clinical manifestations of this will depend on the site and severity of axonal damage, but loss of consciousness is a predominant feature. DAI is typically not demonstrated by computerized tomography (CT) but requires magnetic resonance imaging (MRI).

The force of impact may cause injury to intracranial blood vessels, leading to bleeding within the skull. Traumatic extra-axial bleeds (those occurring outwith the brain) are usually extradural and subdural haematomas. In extradural haematomas, blood accumulates between the dura mater and the skull. This type of bleed is usually due to arterial breach, particularly of the middle meningeal artery, and as such, develops rapidly. Subdural haematomas involve bleeding between the dura mater and the arachnoid mater and, in contrast to extradural haematomas, are usually venous in origin, so develop at a slower pace. Bridging veins in the dural regions are the most common source of bleeding. Both types of haematomas can cause raised intracranial pressure as the bleed enlarges, causing mass effect and compression of the brain tissue. Subdural haematomas can also be seen in non-accidental head injury. An incidental finding of these or a finding inconsistent with the history given, should raise suspicion and consideration of non-accidental injury.

Traumatic subarachnoid haemorrhages can also occur and usually develop in close proximity to cerebral contusions or skull fractures.

Spinal cord injury

Spinal cord injury is rare in the paediatric age group, occurring most commonly as the result of road traffic collisions. The most common cervical fracture involves the first two vertebrae. In addition, spinal cord injury without radiologic abnormality (SCIWORA) is almost exclusively a paediatric problem. This occurs as a result of the elasticity of the cervical spine allowing significant cord injury in absence of X-ray changes.

Thoracic injury

The most common causes of thoracic injury in children are road accidents and falls. Chest injuries are mostly caused by blunt trauma with only a very few due to penetrating injury, and usually occur in conjunction with trauma to other body parts. The chest wall of children is much more compliant than adults, leading to transfer of impact energy to underlying organs and structures with minimal, if any, external sign of injury or fracture. The presence of rib fractures or mediastinal injury indicates very significant and high energy impact. Common underlying injuries include lung contusions, which develop as energy is transferred rapidly to the lungs causing haemorrhage and oedema in the lung tissue, and pneumothoraces. Great vessel trauma is very rare.

Abdominal injury

Children are more vulnerable to major abdominal injuries as a result of pliable rib cages, which provide little protection to solid organs, which are proportionally larger than in adults. In addition, their abdominal wall is thin and provides less impact absorption.

Most abdominal injuries are caused by blunt trauma, often due to road traffic collisions, seat belt restraint and handlebar injury. The pancreas is particularly at risk from handlebar injury. Intra-abdominal organs bleed readily, resulting in hypovolaemia and circulatory collapse. Acceleration and deceleration forces cause injury to organs, which are moved rapidly and may come into contact with the spine. Abdominal injury can be life-threatening and difficult to diagnose quickly in the absence of external signs. Injury to organs such as the spleen and liver manifest themselves rapidly, while bowel or pancreatic injuries may not become clinically evident for several days. A pro­active approach to identifying abdominal injury is needed, especially in high mechanism injuries. Although focused abdominal sonography for trauma (FAST) is a useful tool, it can miss major solid organ injury and it must be combined with clinical judgement.

Burns and scalds

Burns are injuries to tissues usually caused by heat, but also by friction, electricity, radiation (from the sun, for example) or chemicals. Scalds are caused by contact with hot liquid or steam. They are among the most common of childhood accidents. The vast majority of childhood burns and scalds occur within the home.