Early management and complications of spinal cord injuries — II

The anatomy of spinal cord injury
The spinal injury
- The cervical spine injury
- The thoracic and lumbar spine injury
Transfer to a spinal injuries unit

The anatomy of spinal cord injury

The radiographic appearances of the spine after injury are not a reliable guide to the severity of spinal cord damage. They represent the final or “recoil” position of the vertebrae and do not necessarily indicate the forces generated in the injury. The spinal cord ends at the lower border of the first lumbar vertebra in adults, the remainder of the spinal canal being occupied by the nerve roots of the cauda equina. There is greater room for the neural structures in the cervical and lumbar canals, but in the thoracic region the spinal cord diameter and that of the neural canal more nearly approximate. The blood supply of the cervical spinal cord is good, whereas that of the thoracic cord, especially at its midpoint, is relatively poor. These factors may explain the greater preponderance of complete lesions seen after injuries to the thoracic spine. The initial injury is mechanical, but there is usually an early ischaemic lesion that may rapidly progress to cord necrosis. Extension of this, often many segments below the level of the lesion, accounts for the observation that on occasion patients have lower motor neurone or flaccid paralysis when upper motor neurone or spastic paralysis would have been expected from the site of the bony injury. Because of the potential for regeneration of peripheral nerves, neurological recovery is unpredictable in lesions of the cauda equina.

Anatomy of spinal cord injury.

The spinal injury

Treatment should be aimed at stabilising the spine to avoid further damage by movement and also to relieve cord compression.

The cervical spine injury

Patients with injuries of the cervical spine should initially be managed by skeletal traction. Applied through skull calipers, traction is aimed at reducing any fracture or dislocation, relieving pressure on the cord in the case of burst fractures, and splinting the spine.

Cone (left), Gardner-Wells (upper right), and University of Virginia (lower right) calipers.

Reduction of a C4–5 bilateral facet dislocation due to severe flexion injury. Increasing traction weight was applied with the neck in flexion for 3.5 hours to 25 kg ((1)–(4)). (5) shows the final position after 4 hours with head extended and weight reduced to 4 kg traction. The neurological level improved from C5 to C6.

Of the various skull calipers available, spring-loaded types such as the Gardner-Wells are the most suitable for inserting in the emergency department. Local anaesthetic is infiltrated into the scalp down to the periosteum about 2.5 cm above the pinna at the site of the maximum bitemporal diameter, and the caliper is then screwed into the scalp to grip the outer table of the skull. No incisions need be made, and the spring loading of one of the screws determines when the correct tension has been reached. The University of Virginia caliper is similar in action and easily applied. The Cone caliper is satisfactory but requires small scalp incisions and the drilling of 1 mm impressions in the outer table of the skull. Insertion too far anteriorly interferes with temporalis function and causes trismus. The Crutchfield caliper is no longer recommended because of the high incidence of complications.

Skull traction used:

To reduce dislocation
To relieve pressure on spinal cord in case of burst fractures
To splint the spine

When the upper cervical spine is injured less traction is required for reduction and stabilisation. Usually 1–2 kg is enough for stabilisation; if more weight is used overdistraction at the site of injury may cause neurological deterioration. Specific injuries of the upper cervical spine and the cervicothoracic junction are discussed in chapter 6.

Skull traction using Gardner-Wells caliper, with neck roll in position.

Halo applied with the bale arm—an alternative approach to skull traction if early mobilisation into a halo brace is being considered.

A traction force of 3–5 kg is normally applied to the calipers in fractures of the lower cervical spine without dislocation. A neck roll (not a sandbag) should be placed behind the neck to maintain the normal cervical lordosis. Pressure sores of the scalp in the occipital region are common, and care must be taken to cushion the occiput when positioning the patient. When necessary this can be achieved by using a suitably covered fluid-filled plastic bag, having ensured that there is no matted hair that could act as a source of pressure. If the spine is dislocated reduction can usually be achieved by increasing the weight by about 4 kg every 30 minutes (sometimes up to a total of 25 kg) with the neck in flexion until the facets are disengaged. The neck is then extended and the traction decreased to maintenance weight. The patient must be examined neurologically before each increment, and the traction force must be reduced immediately if the neurology deteriorates.

Manipulation under general anaesthesia is an alternative method of reduction, but, although complete neurological recovery has been reported after this procedure, there have been adverse effects in some patients and manipulation should only be attempted by specialists. Use of an image intensifier may facilitate such reductions.

Halo traction is a useful alternative to skull calipers, particularly in patients with incomplete tetraplegia, and conversion to a halo brace permits early mobilisation.

Skull traction is a satisfactory treatment for unstable injuries of the cervical spine in the early stages, but when the spinal cord lesion is incomplete, early operative fusion may be indicated to prevent further neurological damage. The decision to operate may sometimes be made before the patient is transferred to the spinal injuries unit, and if so the spinal unit should be consulted and management planned jointly.

Left: bilateral facet dislocation in a patient with associated cervical spondylosis. Right: incorrect traction—too great a weight and head in extension—leading to distraction with neurological deterioration.

Another indication for operation is an open wound, such as that following a gunshot or stab injury. Exploration or debridement should be performed.

Skull traction is unnecessary for patients with cervical spondylosis who sustain a hyperextension injury with tetraplegia but have no fracture or dislocation. In these circumstances the patient should be nursed with the head in slight flexion but otherwise free from restriction.

The thoracic and lumbar spine injury

flexion-rotation forces. Conservative treatment for injuries associated with cord damage is designed to minimise spinal movement, and to support the patient to maintain the correct posture. In practice a pillow under the lumbar spine to preserve normal lordosis is sometimes used. Dislocations of the thoracic and lumbar spine may sometimes be reduced by this technique of “postural reduction”. However, internal fixation is recommended in some patients with unstable fracture- dislocations to prevent further cord or nerve root damage, correct deformity, and facilitate nursing. As yet there is no convincing evidence that internal fixation aids neurological recovery.

Support position for nursing a patient with a thoracolumbar spinal injury.

Transfer to a spinal injuries unit

In the United Kingdom, there are only 11 spinal injuries units and most patients will be admitted to a district general hospital for their initial treatment. As soon as spinal cord injury is diagnosed or suspected the nearest spinal injuries unit should be contacted. Immediate transfer is ideal, as management in an acute specialised unit is associated with reduced mortality, increased neurological recovery, shorter length of stay and reduced cost of care, compared to treatment in a non- specialised centre. The objects of management are to prevent further spinal cord damage by appropriate reduction and stabilisation of the spine, to prevent secondary neuronal injury, and to prevent medical complications.

Objects of early transfer to a spinal injuries unit:

To prevent further spinal cord damage by reduction and stabilisation of spine
To prevent secondary neuronal injury
To prevent medical complications
To expedite all aspects of rehabilitation

Helicopter transfer of a spinally injured patient.

The choice between immediate or early transfer will depend on the general condition of the patient and also on the intensive care facilities available. Unfortunately, some patients will not be fit enough for immediate transfer because of multiple injuries or severe respiratory impairment. In such cases it is advisable to consult, and perhaps arrange a visit by, a spinal injuries consultant. Transfer to a spinal injuries centre is most easily accomplished by means of a Stryker frame, which can be fitted with a constant tension device for skull traction. The RAF pattern turning frame is similarly equipped and was specifically developed for use by the Royal Air Force. In civilian practice, studies have shown that patients can be safely transferred from emergency departments using the standard techniques for cervical immobilisation described earlier. Tetraplegic patients should be accompanied by a suitably experienced doctor with anaesthetic skills, who can quickly intubate the patient if respiratory difficulty ensues. Transfer by helicopter is often the ideal and is advisable if the patient has to travel a long distance.

Delay in transfer to spinal injuries unit if:

Patient unfit to transfer:
- multiple injuries
- need for emergency surgery
- severe respiratory impairment
- cardiorespiratory instability
Consider visit by spinal injuries consultant