Spinal injuries

Published on 27/02/2015 by admin

Filed under Anesthesiology

Last modified 27/02/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1791 times

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 ways35 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

A detailed neurological examination is essential, including motor function, sensory function (spinothalamic and dorsal column) and reflexes, as well as anal motor function, sensation and reflexes. The vital capacity should be measured. This neurological examination provides the most useful information with respect to assessment of the SCI and to prognosis. However, it may be difficult to conduct on presentation due to head or other injuries, pain, alcohol or the administration of analgesic or other drugs.

In an alert patient SCI may be obvious with limb paralysis or weakness, numbness and absence of reflexes.

With a complete SCI there is muscle paralysis, with somatic and visceral sensory loss below a discrete segmental level. Spinal shock is usually present, with the additional features of muscle flaccidity, absence of tendon reflexes, vaso- and venodilatation, loss of bladder function and paralytic ileus. This term refers to a form of neurogenic ‘shock’ with temporary loss of somatic and autonomic reflex activity below the neurological level of injury. It usually lasts for 1–3 weeks before the recovery of distal reflex activity in the isolated cord segment.

TERMINOLOGY

The terminology for SCI has now been standardised.8

Complete injury refers to the absence of motor and sensory function in the lowest sacral segment.9 A zone of partial preservation exists if there is partial innervation of motor and sensory segments below the neurological level. This term is only used in complete SCI. If partial innervation of motor and sensory function is found below the neurological level and includes the lowest sacral segment (with anal sensation and voluntary external anal sphincter contraction) the injury is defined as incomplete. Grading of complete and incomplete SCI utilises the ASIA impairment scale8 (Table 70.3).

Table 70.3 American Spinal Injury Association (ASIA) impairment scale

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: