Chapter 70 Spinal injuries
There are few injuries that have a more devastating impact on both the patient and their family than spinal cord injuries (SCI). The physical, psychological and functional sequelae of permanent disability are immense. In addition, the economic cost to the individual and to society, with the loss of productivity and costs of hospitalisation, rehabilitation and ongoing care, are enormous.
AETIOLOGY
The incidence of SCI in developed countries is 12–53 new cases per million population per year (excluding deaths before reaching hospital).1 There is some variation in the incidence and causes in different countries. About 80% of SCI are male, usually in the 15–35 years age group.
SCI are due mainly to motor car, motor bike and bicycle accidents (50%), falls (15–20%) and sporting injuries (10–25%).1 Alcohol ingestion is frequently an associated factor. Work-related injuries account for 10–25%, and physical violence for 10–20% of SCI, especially from gunshot injury in the USA. Sporting and recreational injuries appear to be increasing (but with fewer now due to diving), and there is an increasing incidence of SCI in the elderly, especially from falls.2 Ischaemic SCI is occasionally due to aortic injury or cross clamping. Pre-existing spinal pathology predisposes to SCI, including osteoarthritis, spinal canal stenosis, ankylosing spondylitis, rheumatoid arthritis and congenital abnormalities.
Fifty-five per cent of SCI are cervical (most at the C4–6 levels), with thoracic, thoracolumbar and lumbosacral injuries each being 15% of SCI. Forty-five per cent of SCI are complete and 55% incomplete. Between 20 and 60% of patients with SCI have significant associated injuries such as head and chest injuries.1
PATHOGENESIS
SPINAL INJURY
CERVICAL SPINE
Injury to the cervical spine has been classified several ways3–5 relating to the mechanism of injury using the two-column concept. Differences appear to be due to the fact that compression of the anterior column is associated with distraction of the posterior column, and vice-versa. Injuries may be grouped according to the predominant mechanism of injury (Table 70.1) with these mechanisms having characteristic radiological patterns.
Table 70.1 Cervical spine injuries
SPINAL CORD INJURY
Trauma to the spinal cord results in immediate primary and delayed secondary injury processes.
SECONDARY INJURY
An understanding of secondary injury mechanisms has come from experimental SCI in animals.1,7 Local hypoperfusion and ischaemia begin at the site of injury, extending progressively over hours from the site of injury in both directions. There is loss of spinal cord autoregulation, complicated by arterial hypotension with high SCI. Apart from ischaemia, other mechanisms may contribute to the secondary injury. These include the release of free radicals, eicosanoids, calcium, proteases, phospholipases and excitotoxic neurotransmitters (e.g. glutamate).
Petechial haemorrhages begin in the grey matter, progress over hours and may result in significant haemorrhage into the cord. There is oedema, cellular chromatolysis and vacuolation, and ultimately neuronal necrosis. Apoptosis, especially of oligodendrocytes, also occurs.1 In the white matter vasogenic oedema, axonal degeneration and demyelination follow. Infiltration of polymorphs occurs in the haemorrhagic areas. Late coagulative necrosis and cavitation subsequently take place.
CLINICAL PRESENTATION
Spinal and spinal cord injuries should be suspected after severe trauma or head injuries, if there are motor or sensory symptoms or signs, or the patient reports neck or back pain.
NEUROLOGICAL ASSESSMENT
TERMINOLOGY
The terminology for SCI has now been standardised.8
Table 70.3 American Spinal Injury Association (ASIA) impairment scale
INCOMPLETE SCI
Incomplete SCI tend to occur in characteristic syndromes.10
UNCONSCIOUS OR UNCOOPERATIVE PATIENTS
The neurological examination may be difficult if the patient is unconscious or uncooperative. In this case a number of signs may be helpful in drawing attention to a SCI as in Table 70.4. Confirmation of SCI may be established by MRI or somatosensory-evoked potentials (SSEP).
Table 70.4 Signs of SCI in unconscious or uncooperative patients
ASSOCIATED INJURIES
CERVICAL SPINE INJURY/TETRAPLEGIA
Overall with major trauma the incidence of cervical spine injury (CSI) is 1–3%.11 However, 2–10% of patients with head injuries have a CSI. The more severe the head injury, the more likely is CSI to be present. Patients with head injuries should be assumed to have a CSI until proved otherwise. Of patients with a cervical SCI, 25% have some degree of head injury, with 2–3% having a severe injury.1,12
THORACOLUMBAR SPINE INJURY/PARAPLEGIA
Chest injuries are often present and are difficult to assess with the inability to take an erect chest X-ray, and the presence of a mediastinal haematoma associated with the vertebral injury. Contrast-enhanced helical CT of the chest may be used to assess other chest injuries, and to exclude an aortic injury,13 although aortography may be preferred for this purpose.
Abdominal injuries are difficult to diagnose if there is a SCI. However, they should be suspected if there is excessive hypotension, referred shoulder pain, or free gas or fluid seen on X-ray of the spine or chest. Abdominal CT, diagnostic peritoneal lavage or ultrasound may be used to delineate these injuries.14
IMAGING
PLAIN X-RAYS (Figure 70.1)
Plain X-rays remain the primary screening method for suspected spinal injuries in symptomatic patients, except in unconscious or multitrauma patients. However, the absence of a detectable abnormality does not exclude a spinal injury. Lesions may not be seen if the views are inadequate or of poor technical quality, or the observer is inexperienced. Even without these limitations, plain X-rays of the neck frequently miss fractures and subluxations,15,16 and a high index of suspicion should be maintained. Adequate views of the entire cervical spine from the base of the skull down to and including the C7–T1 junction should always be obtained. Abnormalities of the prevertebral soft tissues are often present and indicative of subtle injuries.4
With the cervical spine the three-view trauma series is standard in most hospitals (Table 70.5). This consists of lateral, anteroposterior (AP) and odontoid (open mouth) views. A five-view series with supine oblique views has been recommended as improving the diagnostic yield,17 but other studies show no difference in the detection rate. Lateral and AP views are standard screening views for the thoracolumbar spine.
Table 70.5 Basic examination of plain X-rays of cervical spine
| Must include occipital condyles to C7–T1 junction | |
| Lateral is the most important view and will show most injuries | |
| Check for: | |
COMPUTED TOMOGRAPHY (CT) SCANNING
The sensitivity of CT scanning is much greater than plain X-rays in the detection of spinal injuries,15 especially with the newer multidetector CT machines. CT scanning now has an essential role in the detection and evaluation of spinal injuries, as well as the exclusion of injuries with spinal clearance.18
Indications for CT scanning have been regarded as:
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