Acute injury of the spinal cord

Acute injury of the spinal cord

ORTHOPAEDIC Paradoxical movement of the chest wall with diaphragmatic breathing or the presence of priapism in men may be indicators of a high spinal...

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ORTHOPAEDIC

Paradoxical movement of the chest wall with diaphragmatic breathing or the presence of priapism in men may be indicators of a high spinal injury in the traumatized, unconscious patient. The plantar response (movement of the toes in response to an upward stroke with the pointed end of a patellar hammer along the outer edge of the sole) may be down-going and cannot be relied on, in the acute stage, as evidence of the integrity of upper motor neurones. The abolition of the down-going plantar reflex and establishment of a Babinski reflex (up-going plantar response) may not happen for several days. Elderly patients with hyperextension neck injuries and partial damage of the cord are also difficult to diagnose. Such injuries usually arise from low-velocity injuries (e.g. falls in the home) and are commonly associated with lacerations or abrasions to the forehead. The infarction of the central cord that occurs in these injuries affects the hands more than the legs because cervical fibres are innermost in the long tracts. Elderly individuals may be confused and complain only of clumsiness or stiffness. There may be little radiological evidence of injury. Radiography sometimes shows an increase in thickness of the prevertebral soft tissue shadow or an opening up of the front of the disc where the anterior longitudinal ligament has been torn. MRI is better than radiography, showing oedema and bleeds related to ligamentous injury.

Acute injury of the spinal cord Pradeep Thumbikat Martin R McClelland

Incidence The incidence of injuries that are associated with significant damage of the spinal cord is about 15 per million population per year. Young men are most commonly injured: • 50% of injuries result from road traffic accidents • 40% result from domestic accidents (e.g. falling down stairs) and industrial accidents • 10% result from sports accidents (e.g. diving into shallow water, playing rugby, horse riding, gymnastics). The incidence and causes of spinal cord injury vary widely throughout the world. Gunshots and stabbings are common causes in the USA, whereas falls from trees and into wells account for large numbers in ‘developing’ countries.

Neurological examination A sensory evaluation should be carried out first. Using a disposable pin, start at the side of the neck, progress down the outside of the arm, across the fingers, and up the inner arm to the axilla. From the axilla, proceed down the side of the chest and move round to the front of the abdomen. Inspect the back of the legs and the perineum when checking for sensory changes in the legs. A common mistake in assessing neck injuries is to test sensation on the front of the chest and record a sensory level a few centimetres above the nipples. Sensation to the upper part of the chest is supplied by the fourth cervical nerve through the supraclavicular nerves and is separated from the third thoracic dermatome by an imaginary line (axial line; Figure 1). Thus, injuries of the lower cervical spine can be misdiagnosed as upper thoracic. The last normal sensory segment is the neurological level of the patient. In general, changes in muscle power follow the pattern of pain and temperature loss because their nerve fibre tracks (corticospinal and spinothalamic tracts respectively) are closely related in the spinal cord. Knowledge of motor innervation of muscles is important in carrying out a neurological examination (Figure 2). Incomplete injuries may show selective involvement of part of the cord, giving rise to well-recognized syndromes. Central cord syndrome usually follows a hyperextension injury in an elderly patient. Damage to the middle of the cord results in paralysis predominantly affecting the arms and hands. Anterior cord syndrome – the front of the cord is damaged, with paralysis and loss of pain sensation, but preservation of touch and joint position sense through the posterior columns of the spinal cord. Brown–Séquard syndrome comprises injury predominantly to one side of the spinal cord, causing motor loss on that side, and pain and temperature loss on the opposite side.

Diagnosis Clinical features A diagnosis of spinal cord injury should be suspected in patients with: • neck or back pain • sensory disturbance in the hands or feet • weakness or paralysis of the arms and/or legs. Spinal cord injuries are missed most often because the diagnosis has not been considered, and a detailed neurological examination not performed. Spinal injuries are most likely to be missed in those who: • have head injuries • are inebriated • have incomplete neurological deficits • have pre-existing neurological diseases (e.g. multiple sclerosis). In the case of an unconscious patient with a head injury for whom no history can be obtained and sensation and motor activity cannot be tested, one must remember that forces to the head sufficient to cause unconsciousness are also transmitted to the neck. Hence, spinal injury must be assumed until it has been excluded by investigation.

Pradeep Thumbikat is a Specialist Registrar in Spinal Injuries at the Princess Royal Spinal Injuries Centre, Sheffield, UK. Martin R McClelland is a Consultant in Spinal Injuries at the Princess Royal Spinal Injuries Centre, Sheffield, UK.

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Imaging The thoracic spine is a relatively fixed structure with mobile segments at either end. Thus, fractures tend to occur at the cervicothoracic and the thoracolumbar junctions, where mobile segments meet rigid segments.

Distribution of sensory dermatomes

Radiographs: if a neck injury is suspected, obtain anteroposterior, lateral and open-mouth views of the cervical spine. Shoulder ‘pull-down’ views and ‘swimmer’s’ views are helpful when the C7/ T1 junction is obscured. Oblique views of the lower facets may be informative, especially if dislocations are suspected. (If the diagnosis is difficult, a CT scan (see below) is helpful in providing a reconstruction of the alignment of the lower cervical and upper thoracic spine.) Anteroposterior and lateral radiographs of the suspected injury site should also be obtained, preferably before moving the patient from the examination trolley. High-velocity injuries (e.g. road-traffic accidents) have a high incidence of spinal fractures at more than one level (non-contiguous injuries), hence radiographs should be taken of the entire spine.

C3 C4 T2/3

T2/3

T4 5 6

C5 C6

C5 C6

7 8

T1

T1

9 10 11 12

C7 C8

C7

L1 S5 L3

L4

L5

S1

L2

C8

CT and MRI provide additional information on the: • integrity of the posterior elements • stability of the fracture • degree of canal encroachment • ligamentous damage • extent of cord injury (Figure 3).

L3

L4

Acute management

L5

Autonomic disturbance Injury to the spinal cord, especially high lesions, has a profound effect on physiology. Loss of sympathetic tone (due to damage to the sympathetic fibres which leave the cord from the T1 to T11 segments) results in peripheral vasodilation. This results in a lowering of blood pressure and an inability to respond to environmental temperature changes, leaving the patient susceptible to hypothermia. Bradycardia, which results from disturbance of sympathetic outflow to the heart and unopposed vagal activity, can be rendered more profound (even to the point of cardiac arrest) by procedures which may be necessary, but which stimulate the vagus. Such procedures (e.g. oropharyngeal suction, endotracheal intubation) should not be carried out in the presence of bradycardia unless atropine has been given or is immediately available. It is difficult to differentiate neurogenic hypotension from hypotension related to hypovolaemia. A fall in blood pressure should not be regarded as due solely to altered physiology until causes of acute blood loss (e.g. haemothorax, intra-abdominal trauma, hypovolaemia associated with multiple fractures) have been excluded, especially in high-velocity trauma. Patients with high lesions have a poor respiratory reserve and should not be over-transfused because it is easy to precipitate pulmonary oedema and hence respiratory failure.

S1

1

Motor innervation of muscles Muscle Deltoid Biceps Wrist extensors Triceps Finger flexors Hand intrinsics Hip flexors Hip adductors Quadriceps Ankle dorsiflexors Hamstrings Ankle plantar flexors

Nerves C5 C5 C6 C7 C8 T1 L1, L2 L2, L3 L3, L4 L4, L5 L4, L5, S1 S1, S2

Corticosteroids: the efficacy of corticosteroid therapy in acute injuries of the spinal cord is controversial. Methyl prednisolone is associated with an increased incidence of complications and may actually have an adverse effect on morbidity or mortality.

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C6 fracture with a burst component a

c

b

a Lateral radiograph of the cervical spine, b axial CT scan and c T2-weighted sagittal MRI scan show fracture extending across the three columns, causing extensive injury of the cord (bright signal within the cord). Also, note the bright signal change in c along the anterior aspect of the vertebral bodies (arrow), suggesting ligament damage. The posterior elements of C4 are seen fractured in a (arrows). CT scans are most useful in delineating the bony injury, whereas MRI scans help to identify the extent of cord damage, disc injuries and ligamentous damage. 3

Abdomen Major intra-abdominal trauma may be difficult to detect in complete lesions of the cord because of the absence of pain or guarding. The abdomen should be examined for bruising and distension. Haematuria may be indicative of renal trauma, and may suggest injury to other viscera. Ultrasound or contrast-enhanced CT scanning may be used to investigate the stable patient suspected of having intra-abdominal trauma; peritoneal lavage is reserved for emergencies. Bowel sounds are usually present in the early stages after injury, though ileus almost always develops. The patient should be kept on ‘nil by mouth’ until the ileus has reversed. Unless there are signs of abdominal distension, it is not usually necessary to pass a nasogastric tube. Abdominal distension must be prevented because it may hinder the free movement of the diaphragm, and thus cause respiratory insufficiency. Stress peptic ulceration with perforation or haemorrhage is no longer a common complication of acute injury of the spinal cord because of the routine use of prophylactic H2-receptor blockers and proton pump inhibitors. These agents are given parenterally for the first few days and then orally while the patient is confined to bed. Perforation of an ulcer may be difficult to recognize because

Prophylactic anticoagulation: before the introduction of prophylactic anticoagulation, pulmonary embolism was the most common cause of death following survival from acute injury of the spinal cord. In the absence of contraindications (e.g. head injury, significant haemorrhage), anticoagulation should start 24 hours after injury. Low-molecular-weight heparin (enoxaparin 40 mg or equivalent) is started initially; full oral therapy with warfarin is delayed until resolution of any ileus. Warfarin doses are titrated to maintain the International Normalized Ratio between 2 and 2.5. Pharmacological prophylaxis should be combined with mechanical measures such as: • compression stockings • sequential calf compression • frequent turns to provide protection against deep vein thrombosis and pulmonary embolism. Respiration Generally, patients with lesions below the level of C5 are able to ventilate adequately, unless they have superimposed chest problems. Paralysis of the intercostal muscles in high lesions results in paradoxical movement of the chest wall, with indrawing of the intercostal spaces during inspiration. Such patients are almost entirely dependent on diaphragmatic breathing, and have a considerably reduced vital capacity. Further respiratory insults (e.g. lung contusion, pneumothorax, haemothorax) may lead to respiratory failure (Figure 4). Monitoring respiratory rate, vital capacity and oxygen saturation gives warning of respiratory insufficiency. In the case of cervical lesions, respiratory failure may be due to ascent of the neurological deficit with subsequent diaphragmatic paresis. Paralysis of the abdominal muscle prevents effective coughing and clearance of chest secretions. Respiratory physiotherapy, breathing exercises and assisted coughing are started at the earliest possible opportunity to minimize the incidence of respiratory complications.

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Factors predisposing to respiratory failure Rising neurological level Over-transfusion Paralytic ileus Rib fractures Haemothorax Pneumothorax Pulmonary contusion

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of the paucity of abdominal symptoms and signs. If suspected, a lateral decubitus radiograph of the abdomen may show the presence of free gas in the abdomen.

Thoracolumbar injury: a patient with a thoracolumbar injury may be ‘log-rolled’ on to his side using a long, thin lumbar pillow positioned in the hollow of the back.

Bladder Until the patient’s condition has stabilized, the bladder should be drained with an in-dwelling catheter because it allows close monitoring of urine output. With stabilization, intermittent catheterization (4–6 hours) can be started, with fluid intake controlled to achieve bladder volumes of 500–600 ml. Patients with flaccid bladders who have sufficient dexterity are established on permanent intermittent self-catheterization; men with supraconal lesions of the cord are established on reflex bladder emptying into a condom urinal system. If the patient develops a urinary tract infection that requires treatment with antibiotics, re-insertion of an in-dwelling catheter is not infrequently necessary until the infection has been eliminated.

Cervical injury: the shoulders may be held flat against the bed to maintain alignment of the cervical and upper thoracic spine, while the pelvis is twisted to bring one leg uppermost. This leg and the back are then supported with pillows to relieve pressure on the sacrum and uppermost buttock. If this technique is used, the skin over the shoulder blades should be inspected at regular intervals. Pressure sores can develop rapidly because the patient is unable to feel or move. The patient’s position should be changed every 2–3-hours. The skin should be kept clean and dry, and evidence of formation of incipient sores should be sought at each turn. Pressure must be kept off any areas of skin where redness persists.

Fracture management

Bowel In the initial stages of acute injury of the spinal cord, the rectum is flaccid and evacuation should be carried out manually, beginning 2–3 days after injury and continuing daily or on alternate days. With the return of reflex anal activity, evacuation can be achieved using: • digital stimulation • suppositories • micro-enemas. Establishing a regular bowel regimen commonly requires the addition of a bulking agent and stool softener to the diet, along with regular aperients.

Maintenance of alignment Skull traction should be applied to cervical injuries to establish and maintain alignment. Gardner–Wells skull callipers (which have a built-in tension indicator) are the simplest and safest to apply. The calliper pins are sited about 2 cm above the ears (in line with the external auditory meatus). Traction along this line produces the required extending moment about the neck. A larger extending moment can be applied by positioning the callipers further forward, but fixation of the temporalis muscle by the pins can result in trismus. The force needed to maintain alignment varies; for example, it is: • 2 kg in a frail, elderly patient with a high cervical fracture • 5 kg in a fit, young man with a low neck injury. If there is major disruption, large forces over long periods can cause considerable distraction at the fracture site and put traction on the cord. An alternative to traction for maintaining alignment is a well-fitted Halo jacket.

Physiotherapy Early chest physiotherapy, involving assisted coughing and breathing exercises, is vital for all patients with acute injury of the spinal cord and for those with a history of chest disease or associated chest trauma. Joint and muscle contractures that can cause movement restrictions can develop rapidly. Thus, the patient’s arms and legs are put through a full range of passive joint movements as soon as possible after the injury. It is essential (especially in elderly patients) to maintain a good range of shoulder movements; stiff, painful shoulders can compound subsequent disability. With lumbar fractures, passive flexion of the hips should be limited to 70° to avoid unrolling of the lumbar lordosis. A programme of strengthening of non-paralysed muscles should also be initiated.

Reduction of facet dislocation Reduction of facet dislocation requires traction forces much greater than that needed for maintenance of alignment. Unifacet dislocation: the dislocated facet can be determined by observing the patient from the head of the bed; the chin is often turned away from, and the head tilted towards, the side of the dislocation. Classically, on the lateral radiograph, there is a forward shift of about 25% of vertebral body diameter of the upper vertebra on the one below (Figures 5a, b and 6). Apply axial traction for the initial attempt at reduction. If the dislocation is unresponsive, the neck may be slightly flexed and the head turned away from the side of the dislocation to unlock the facet. Traction is increased by 2 kg every 10–15 minutes to allow the tissues to stretch. Traction weights of 30 kg or more are often required, and reduction with 70 kg has been reported. Radiographs are taken with each increment in weight until the dislocation is reduced, whereupon the neck is brought into extension and the weights reduced to maintenance level. The patient is questioned and repeatedly examined for changes in neurology during this period. The final phase of the reduction may be facilitated by

Nursing Maintaining alignment Nursing care of a patient with acute injury of the spinal cord is directed towards: • maintaining alignment of the spine • preventing damage to the skin. All manoeuvres (lifts, rolls, twists) required for skin care and pressure relief are carried out by trained staff. The patient should be lifted by 3–5 persons acting in unison. During turning, alignment of the spine is maintained by the use of dedicated turning beds (e.g. Stoke–Egerton bed) and specific nursing techniques.

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a Lateral cervical radiograph of a unifacet dislocation of C5 on C6.

a

b Facet views of the same injury as in a. Note the loss of apposition of the facet surfaces (arrows) and the change in rotational alignment of the spine as evidenced by the visibility of the neural foraminae below the level of the dislocation and the facet articulations above.

b

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neurology, traction may be maintained and an elective open reduction may be planned. In patients with partial neurological lesions, reduction is best achieved within 48 hours because late reduction can cause neurological deterioration; this may be due to the cord having become oedematous and more sensitive to the trauma of manipulation. Bilateral facet dislocation: a patient who has bilateral facet

6 Anteroposterior radiograph of unifacet dislocation of C6 on C7, showing an increase in the intraspinous process distance (arrows), and a shift of the alignment of spinous processes above the level of the dislocation towards the side of the dislocation.

giving diazepam intravenously to relax the paraspinal muscles (but diazepam should be titrated so that the patient is not rendered unresponsive to questioning or examination). Manipulative reduction under general anaesthesia should (if time and neurology allow) be carried out after obtaining MRI scans of the neck to exclude a concomitant disc prolapse. Anaesthesia carries the risk of not being able to monitor neurology, and is best undertaken by those with experience of the technique. If unilateral facet dislocations cannot be reduced by the above means, emergency surgery is seldom necessary. There is usually a reasonable degree of stability and, in a patient with intact

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7 Lateral radiograph of the cervical spine showing a bifacet dislocation of C5 on C6. Note the loss of apposition of the facet surfaces and complete disruption of the posterior ligamentous complex as evidenced by the distance between the spinous processes (arrows).

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dislocation and who is neurologically intact is in an extremely dangerous situation. If traction succeeds in reducing one of the facets, there is some added stability and open reduction can be done in a planned manner. If both facets remain dislocated, immediate open reduction should be considered (Figure 7). Fixation: after successful reduction, the ligamentous disruption that occurs with facet dislocation should be treated by some form of fixation, such as a posterior cervical fusion using interspinous wiring and bone graft. Thoracolumbar injuries The three-column classification of thoracolumbar injuries by Francis Denis in 1983 is the easiest to use in the clinical setting in the UK. It emphasizes the importance of distinguishing between stable ‘wedge’ fractures and unstable ‘burst’ fractures. Serious thoracolumbar injuries can be managed conservatively or by internal fixation. Conservative management may involve 6–10 weeks of nursing lying flat in bed followed by mobilization in a spinal brace. Abandonment of conservative treatment should be considered if: • there is continued progression of a neurological lesion after admission • displacement of the fracture precludes conservative management • surgery may improve recovery of the nerve root at the site of the injury • associated injuries (e.g. head, chest) can be better managed following fixation of the spine. Whether decompressive surgery aids neurological recovery remains unproven. It carries a small risk of neurological deterioration in patients with incomplete injury of the cord. Decompressive laminectomy should not be carried out on its own because it increases the instability at the fracture site. Modern anterior and posterior fixation devices have lessened (but not totally solved) the problems of implant failure and loss of correction. This may be fixed by: • a posterior approach with interpedicular fixation (Figure 8a) • an anterior approach and fixation with a Moss cage and Kaneda fixator (Figure 8b). u

a Interpedicular fixation of a fracture/ dislocation.

FURTHER READING Coleman W P, Benzel D, Cahill D W, Ducker T, Geisler F, Green B et al. A critical appraisal of the reporting of the National Acute Spinal Cord Injury Studies (II and III) of methylprednisolone in acute spinal cord injury. J Spinal Disord 2000; 13: 185–99. Grundy D, Russell J, Swain A. ABC of spinal cord injury. 3rd edition. London: BMJ Publishing Group, 1996.

b Anterior decompression and fixation with a Moss cage and Kaneda fixator. 8

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