Spinal trauma - Clinical Tree

Essentials

1
Clinically significant cervical spine injury can be confidently eliminated in conscious, clear-headed patients below 65 years of age using clinical examination criteria (as described in National Emergency X-Radiography Utilization Study (NEXUS) and Canadian C-spine rules) alone.
2
Physical examination alone does not assist in the diagnosis of unstable vertebral injury unless the deformity is gross.
3
A lack of neurological symptoms and signs does not eliminate spinal column injury or spinal cord at risk.
4
A patient can be ambulant and still have a major vertebral injury, even a potentially unstable one.
5
The natural history of spinal cord injury may lead to progressively increasing symptoms commencing some hours after the incident.
6
Magnetic resonance imaging is evolving as the imaging modality of choice in patients with neurological signs.
7
The likelihood of significant vertebral injury in unconscious trauma victims is 10%; 2% of all trauma victims with significant altered conscious state have a spinal cord injury.
8
Although spinal immobilization is a standard of care for protecting the spine, the use of these devices can have adverse clinical effects.
9
Methylprednisolone is not recommended in most Australian and international centres if given, however, it should be within 8 hours after spinal cord injury in order to improve both motor function and functional outcome.

Acknowledgement

The author of this chapter in the previous edition of this textbook was Jeff Wassertheil. The text in this new edition is based on the original chapter, for which Jeff Wassertheil must be acknowledged.

Introduction

Spinal cord injury is one of the most disabling traumas, causing major and irreversible physical and psychological disability to the patient and permanently affecting his or her lifestyle. The emotional, social and economic consequences affect the individual, family, friends and society in general.

Approximately 2% of adult victims of blunt trauma suffer a spinal injury, and this risk is tripled in patients with craniofacial injury.

Motor vehicle collisions, falls and sporting injuries—notably diving and water sports—are the major causes of acute spinal cord injury in Australia. Road traffic accidents account for about half of all spinal injuries. Despite the work to minimize spinal injuries in contact sports, such as rugby, serious spinal cord injuries still occur. Young people are most often affected, but minor falls in the elderly or low-impact injuries in people with pre-existing bony pathology can also cause spinal cord damage. Spinal cord injury due to pathological vertebral fractures may be the first presentation of malignancy.

Observations from two studies suggest that possibly preventable neurological deterioration may be due to one or more of the following:

The injury not being recognized initially (e.g. not being specifically examined for, being occult or masked by other injuries)
The onset of the secondary effects of the spinal cord injury involving oedema and/or ischaemia
Aggravation of the initial spinal cord lesion by inadequate oxygenation and/or hypotension
Aggravation of the initial spinal cord lesion by inadequate vertebral immobilization

Pathophysiology

Level of vertebral injury

The level of neurological injury in patients who sustain spinal injuries is variously reported. In studies from Victoria and New South Wales, the distribution of the level of injuries was cervical 60%, thoracic 30%, lumbar 4% and sacral 2%.

Spinal cord injuries occur most commonly at the level of the 5th, 6th and 7th cervical vertebrae, largely because of the greater mobility of these regions. The C5–C6 and C6–C7 levels account for almost 50% of all subluxation injury patterns in blunt cervical spinal trauma.

Associated injuries

There are three noteworthy observations from associated injuries in patients with spinal injury:

Approximately 8% to 10% of patients with a vertebral fracture have a second fracture of another vertebra, often at a distant site. These second fractures are usually associated with the more violent mechanisms of injury, such as ejection or rollover. Secondary injuries are usually relatively minor and stable (e.g. fractures of the vertebral processes), but occasionally they may be major and may also be associated with neurological damage. Therefore when ‘thinking spine’, it is important to ‘think whole spine’ and, in particular, to attempt to avoid rotation of the vertebral column.
Owing to the mechanism of injury, many patients with spinal injuries have other associated injuries, including head, intrathoracic or intra-abdominal injuries, which may modify management priorities.
Patients may complain of pain from other injuries; hence a back or neck injury may go unnoticed. Pain may often not be a significant feature despite severe vertebral column damage. Furthermore, spinal pain may take some time to become apparent because of other pathological processes modifying the pain, such as swelling and inflammation.

Spinal trauma may result in several injuries directly related to the spinal cord. Specific injuries—such as vertebral injuries, spinal shock, spinal cord injuries and their neurological symptoms—are described later in this chapter.

Effects of spinal cord damage on the autonomic nervous system

Autonomic nervous system effects are mentioned here because important pathophysiological mechanisms must be understood to deliver optimum care and treatment to patients with spinal cord injuries.

The entire sympathetic nervous system and pelvic parasympathetic outflow is transmitted via the spinal cord. In an injury higher than the upper thoracic vertebrae, there is significant impairment of total body sympathetic and pelvic parasympathetic functions. The extent and severity of autonomic dysfunction is dependent on the segmental level or levels affected and the extent or completeness of the neurological insult.

Direct effects

Direct effects include manifestations related to the cardiovascular, gastrointestinal, urogenital and thermoregulatory systems.

Cardiovascular effects

In complete quadriplegia, sympathetic denervation causes relaxation of resting vasomotor tone, resulting in generalized systemic vasodilatation. It is recognized during initial assessment by dry extremities with variable warmth and colour. In males there may be penile engorgement or priapism. Owing to the peripheral vasodilatation, there is a drop in total peripheral resistance with consequent hypotension (neurogenic shock). Under normal circumstances, this would result in a baroreceptor response in order to achieve compensation. However, as the effector arm of the sympathetic nervous system is paralysed, the normal compensatory effects of tachycardia and vasoconstriction do not occur. The vagus nerve carrying parasympathetic supply to the heart is unopposed, with resultant bradycardia. The higher and more complete the spinal cord injury, the more extensive the autonomic dysfunction.

The usual symptoms and signs of the shock process in response to hypovolaemia cannot occur, as tachycardia and vasoconstriction are mediated by the sympathetic nervous system, which has been interrupted by the high spinal cord lesion.

Gastrointestinal effects

Following spinal cord injury, a paralytic ileus develops. This is usually self-limiting and recovers over 3 to 10 days. Paralysis of sphincters occurs at the lower end of the oesophagus and at the pylorus; as a consequence, passive aspiration of the stomach contents, especially of fluid, is a potential problem. Furthermore, owing to paralysis of the thoracic and abdominal wall musculature, the capacity to cough and hence clear the airway is diminished. In quadriplegia and high paraplegia, occult fluid aspiration due to passive regurgitation of retained gastric contents may not be recognized. The airway therefore requires close observation and active protection. A nasogastric tube must be inserted and gastric contents drained.

Urinary effects

Urinary retention is partly the consequence of acute bladder denervation and, in the early post-injury phase, due to spinal shock. Catheter insertion is required to prevent over-distension of the bladder in order to optimize recovery. This also permits measurement of urinary output.

Thermoregulatory effects

Following cervical or upper thoracic spinal cord injury, the patient effectively becomes poikilothermic. In a cold environment, he or she is unable to vasoconstrict to conserve heat or shiver to generate heat. The patient is already peripherally vasodilated, which promotes loss of heat and lowers body temperature. In the warm environment, although the patient is already peripherally vasodilated, the capacity to sweat is sympathetically controlled and therefore lost.

Pre-hospital issues

Extrication and immobilization

Emergency medical services (EMS) personnel are sent to see trauma patients in difficult circumstances. For instance, a patient may be stuck in a vehicle, partially submerged in water or found in a small and inconvenient place. These circumstances often make it hard to carefully handle and immobilize the cervical spine initially. Several devices have been developed to extricate a trauma patient from a crashed vehicle with maximum in-line protection of the spinal column.

A restless patient—due to hypotension, hypoxia, drug abuse, anxiety or other causes—makes it even harder to immobilize the spine. Depending on local protocols, training and skills, EMS personnel should either be able to treat the cause of the restlessness or sedate such a patient in order to protect the cervical spine.

Next to resuscitation interventions following the ABCDE (airway, breathing, circulation, disability and exposure) approach, in-line protection of the total spine should become the focus of attention. Trauma patients should remain in immobilization devices until spinal trauma has been excluded and splinting of specific injuries can be effected. However, they do not need to be left in the devices applied by pre-hospital care providers: these are often structured to provide rigid immobilization for initial stabilization and transport. Nor should they be left tied to spine boards or wrapped in extrication devices, as these are uncomfortable and can cause unwanted cutaneous pressure injuries. Moreover, tight webbing and wraps can interfere with respiratory excursion. In general the pre-hospital devices are removed and replaced with others that are more appropriate for the emergency department (ED) environment.

In-line protection of the spine

In case of suspected injury, in-line protection of the spine is important, although more than 90% of suspected patients do not have an unstable C-spine injury. Recommendations for techniques of immobilisation are evolving. The International Liaison Committee On Resuscitation (ILCOR) 2015 consensus on science and treatment recommendations (CoSTR) regarding immobilization of victims with suspected spinal injury recommend against the use of semi-rigid cervical collars by first aid providers. The Australian and New Zealand Council on Resuscitation (ANZCOR) has formulated the following recommendations:

Immediate recognition of the potential for spinal injury
Minimal movement and handling of victim
Immediate assessment of the victim
Immediate spinal care with manual techniques
Early transfer for definitive assessment and care

The effectiveness of common immobilization techniques is largely unproven and there are side effects from unnecessary immobilization. There is even evidence that immobilizing the cervical spine does not significantly reduce neurological injury.

Several types of devices exist and are used either alone or in combination. In Australia different approaches are used following different regional protocols. The common combination in out-of-hospital spine care comprises a spine board and associated padding to ensure a normal curvature of the spine. Nevertheless there is a decline in the use of the spine board because of its side effects. Other devices, such as extrication devices—not primarily designed as spinal immobilizers—have been used to splint the spine in special circumstances.

The various devices and techniques are variably effective and do not completely immobilize. However, they have generally been tested on uninjured subjects with normal muscular tone and posture.

As mentioned previously, spinal immobilization can be harmful. Standard spinal immobilization applied to otherwise healthy subjects has resulted in significant spinal pain in all of the subjects. Spinal immobilization can mask life-threatening injuries. Cervical collars have been shown to increase intracranial pressure. Spinal immobilization restricts pulmonary function in healthy adults and children. Prolonged immobilization of the cervical spine with rigid pre-hospital rescue collars and other immobilization devices may unnecessarily add to patient discomfort and the need for ongoing spinal nursing. Tissue perfusion in the sacral area is adversely affected within 30 minutes on a rigid spinal board. This predisposes to pressure area problems and problematic decubitus ulceration.

Therefore the pre-hospital devices should be removed as soon as possible after the patient’s arrival in the ED, usually immediately after the primary survey, and replaced with more appropriate ones for the ED environment.

First treatment options

Primary survey

Patients presenting with a potential spinal cord injury are managed in keeping with the approach for any patient who has experienced a major trauma. Therefore a standard approach of primary survey, resuscitation, secondary survey and definitive management is adopted.

Specific attention should be paid to the following important issues in the assessment and treatment of patients with (potential) spinal injury.

Airway

Assessment of the airway is vital in the management of suspected spinal cord injury, especially when the cervical spine is involved. Passive regurgitation and aspiration of fluid stomach contents may occur as a result of blunting or absence of cough, gag and vomiting responses. This is especially the case with higher cervical injuries. Therefore the insertion of a nasogastric tube is of vital importance in minimizing the likelihood of aspiration. In quadriplegia and high paraplegia, unopposed vagal action owing to functional total or near-complete sympathectomy predisposes the patient to bradycardia on vagal stimulation of the pharynx. It is important that such patients have electrocardiographic (ECG) monitoring and that atropine be immediately available to block these effects. Pretreatment with atropine prior to manipulation of the upper airway is a consideration.

Advanced airway management

Early endotracheal intubation and assisted ventilation should be considered in patients with quadriplegia and high paraplegia. Regular assessment of respiratory status is undertaken and includes continuous pulse oximetry and frequent measurement of vital capacity in order to detect fatigue.

Blind nasal or endoscopic-assisted intubation under local anaesthesia is the preferred mode of non-emergency intubation. Additionally, every manipulation of the head and neck of the patient should be done with extreme caution to minimize further damage to the vulnerable spine.

The literature suggests that video-laryngoscopy results in less overall movement during intubation, and it does not seem to have an impact on cord injury.

Since the rocuronium antagonist sugammadex has become widely available, rocuronium has become the muscle relaxant of first choice in many settings because of the beneficial side-effect profile. Suxamethonium is therefore used less often but still acceptable for a rapid-sequence intubation in the emergency setting. The hyperkalaemia associated with denervation is a concern in injuries more than 10 to 12 hours old (see Chapter 2.1 ).

Breathing

Ventilation in patients with spinal cord injury may be affected by the level of cord injury, aspiration and primary lung injury. In the absence of major airway obstruction and flail chest, the presence of paradoxical breathing is considered highly suggestive of cervical spine injury. Paradoxical breathing occurs because of loss of motor tone and paralysis of thoracic muscles innervated by thoracic spinal segments. Diaphragmatic action results in a negative intrapleural pressure. As a consequence of chest wall paralysis, the tendency is for the soft tissues of the thorax to ‘cave in’, producing paradoxical chest wall movement. The diaphragm must then undertake the full work of breathing, including overcoming added resistance to ventilation caused by paradoxical chest wall movement. In addition to standard assessment of respiratory status, continuous pulse oximetry and assessment of vital capacity is necessary. Early intubation should be considered if vital capacity is inadequate or falling.

Ventilation may be reduced for several reasons:

The diaphragm may simply fatigue and require assisted ventilation.
A progressively ascending spinal cord injury owing to either further primary damage or secondary ascending spinal cord oedema may encroach upon the third to fifth cervical segments.
The same segments may be involved with the initial injury and thus the diaphragm may itself be partially paralysed.
The consequences of coexisting chest trauma must also be taken into consideration, as respiration may be embarrassed by the natural progression of thoracic cage, pulmonary or intrapleural injuries.

Circulation

Volume resuscitation in the resuscitative phase of the primary survey is undertaken in keeping with usual practices. With the exception of perhaps diving injuries, victims of hypotensive trauma should be considered as suffering from intravascular volume depletion and bleeding until proved otherwise. Standard initial volumes of resuscitation fluid will not adversely affect haemodynamic status. Owing to peripheral vasodilatation, the spinal cord trauma patient’s intravascular volume is relatively depleted; therefore volume preloading is appropriate. However, unnecessary volume overloading in an attempt to raise systolic blood pressure substantially will lead to acute pulmonary oedema.

After resuscitation fluids have been administered, haemorrhage controlled, ongoing losses replaced and fluid required for oedema responses to injury considered, routine maintenance fluids are all that is needed.

Paralysis of the sympathetic nervous system and hence the compensatory mechanisms for intravascular volume depletion necessitates a heightened suspicion of ongoing bleeding, the signs of which may be dramatic or subtle. Progressive hypotension is a key sign. Paradoxically, the heart rate may rise progressively from a bradycardia of 50 to 60 beats/min to more normally acceptable rates. It is uncertain by which mechanism this pseudo- or relative tachycardia of quadriplegia occurs. One thought is that with progressive hypotension and brain stem hypoperfusion, the vagal effects are switched off by the brain stem, thus allowing the heart rate to rise towards a more normal or denervated range. In addition, the skin may develop patchy or blotchy cyanosis. This is due to a sluggish peripheral circulation and hence locally elevated levels of deoxygenated or desaturated haemoglobin.

In cases of spinal cord injury, the impact of functional sympathectomy will depend upon the level and completeness of the neurological injury. Complete injuries above T1 and perhaps T4 can be expected to have clinically significant manifestations of neurogenic shock. The clinical signs are bradycardia due to unopposed vagal action, peripheral vasodilatation and cessation of sweating. Peripheral vasodilatation is responsible for variable cutaneous manifestations. Initially, flushing can be expected; however, the skin may be pale or cyanosed and its temperature elevated, reduced or within normal limits. The state of these signs is dependent on perfusion pressure, adequacy of oxygenation and the ambient temperature.

Priapism in a trauma patient is due to penile vasodilatation and is regarded as a highly suggestive sign of spinal cord injury.

Circulatory status is best assessed by conscious state, urine output and venous pressure monitoring. In the early phases of management, close urine output monitoring is of major importance. Early insertion of the urinary catheter allows measurement of urine output, may assist in identifying occult renal tract injury and also prevents undesirable bladder overdistension.

Inotropic support is often unnecessary. However, satisfactory cerebral perfusion is essential. In order to maintain cerebral perfusion, a mean arterial pressure (MAP) of at least 60 mmHg is recommended. In the patient with a previously normal Mini Mental State Examination, deterioration may suggest intracranial hypoperfusion due to either intracranial trauma or the neurogenic shock process. Chronotropic and vasoconstrictor agents are occasionally required. These are more likely to be necessary in older patients or those suffering from hypertension who are now relatively hypotensive despite volume loading. Chronotropic agents are occasionally required for patients prescribed β-blocker and/or peripheral and central vasodilator drugs. Likewise patients with established cerebrovascular disease may require higher perfusion pressures than the resting pressure of the quadriplegic.

The degree of the physiological effects on the circulation will depend on the site and completeness of the injury. Spinal cord injury below the sympathetic outflow will have little effect on the circulation; complete spinal cord injury above the thoracic outflow will produce a total body sympathectomy. A complete spinal cord injury in the mid-thoracic segments should result in preserved vasomotor function in the head, neck and upper limbs. Cardiac reflexes should also be relatively well preserved. Vasomotor tone to the abdominal cavity, pelvis and lower limbs will be paralysed. Likewise, incomplete lesions will have a varying effect depending on the site and completeness of the injury. Careful establishment of the segmental level and degree of spinal cord injury on secondary survey will assist in anticipating the likely extent of autonomic dysfunction.

The denervated lung is intolerant of volume overload. Therefore careful monitoring of fluid balance, including urine output and, in circumstances of low urine flow, central venous pressure, is required.

Disability

Spinal cord injury has an association with significant head trauma. In patients with an altered conscious state due to head trauma, early brief assessment of mental state and pupillary reflexes is important. All trauma victims with altered conscious state require spinal immobilization until spinal cord or unstable vertebral injury is excluded on physical examination and investigation.

In patients with injuries at or above T4, bilateral Horner syndrome may be present with relative pupillary constriction.

Exposure

As a spinal cord injury may be one of several injuries, the patient should be fully exposed and then wrapped in a warming blanket in keeping with a routine approach to patients with multisystem trauma.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here