Cervical spine trauma

SPINAL injury is relatively uncommon. In Scotland there is a single National Spinal Injuries Unit which admits between 150 and 200 patients per year from a population of just over 5 million. The total comprises approximately 50 per cent patients who have sustained a cervical spine injury and 50 per cent who have sustained a thoracolumbar injury. This article will deal with cervical spine trauma primarily, although many of the issues and risks also apply to thoraco-lumbar spinal trauma.

The commonest causes of cervical spine injury are road traffic accidents, falls, sports/leisure related activities and assaults. Cervical spine trauma occurs with or without primary neurological injury. Spinal cord injury may be described as ‘complete’, with no retained motor or sensory function, or ‘incomplete’ with varying degrees of residual sensation and voluntary motor function.

The prognosis for recovery is substantially better in those patients who have an incomplete injury whereas only 2 per cent of patients who have a complete spinal cord injury will recover sufficiently to be able to walk again. Even patients with a severe incomplete injury who have retention of spinothalamic (pain and temperature) sensation have an approximate 70 per cent chance of being able to recover sufficiently to walk. Patients who have an incomplete cord injury are also likely to benefit most with an early diagnosis and appropriate management as failure will lead to what is in effect a secondary spinal cord injury.

The five main types of cervical spine injury are:

• vertebral fractures
• disco-ligamentous injuries
• penetrating injuries
• injury associated with pre-existing spinal pathology such as ankylosing spondylitis or rheumatoid disease
• distraction injuries.

This article will primarily focus on vertebral fractures and disco-ligamentous injuries which are the most frequent forms of cervical spine trauma.

Diagnosis and recognition

The diagnosis of cervical spine trauma is based on a relevant clinical history, a clinical examination and confirmation by radiological imaging. Of these the historical and radiological evidence are the most valuable, at least in terms of initial recognition and diagnosis. A detailed neurological examination is not necessary at this stage. A patient may present with a history of neurological symptoms, perhaps transiently involving all four limbs, or perhaps just involving one of the upper limbs. There may be no neurological signs at the time of initial assessment, but this historical evidence is salient and means that there has been a primary neurological injury, albeit transient, and that a secondary neurological injury is therefore possible.

Simple, early and rapid cervical spine immobilisation is carried out with the primary purpose of keeping the ‘spine in line’ and preventing movement. At this time the local spinal injuries unit or the neurosurgical/orthopaedic department responsible for receiving patients with spinal trauma should be contacted. Advice will be provided by that specialist unit with regard to further management and in particular various measures such as the use of anti-DVT techniques, avoidance of volume loading to correct neurogenic hypotension, etc.

Cervical spine radiology

The most useful combination of radiological investigations is a good quality lateral X-ray of the cervical spine as the initial investigation supplemented by multi-slice CT scan with sagittal reconstruction. During this process the patient’s cervical spine requires to be maintained ‘spine in line’ and treated as if there is a fracture or subluxation. Large numbers of very fine horizontal CT slices through the whole cervical spine are of little initial practical value and may even be confusing or distracting in terms of diagnosis. High quality sagittal reconstructions that demonstrate the rightsided facet joints through the centre, to the left side facets provide the most useful screening information.

The use of magnetic resonance imaging in the early diagnostic stages is of limited value. It may demonstrate abnormal high signal derived from the spinal cord itself and ligamentous or disc-related damage but this investigation can be carried out later in the specialist unit. There is also little place for cervical flexion/extension views in the early stages of diagnosis and management.

One recurring feature of patients whose cervical spine injury is not diagnosed for weeks or months is that the initial lateral cervical spine X-ray was reported to be normal. The initial injury may have been a fall or road traffic accident but reassurance is taken from a radiological opinion which states that the lateral X-ray shows no abnormality. Persistent symptoms, however, demand repeat investigations. The patient complaining of ongoing neck pain may be treated in a cervical collar but if one week after injury the neck pain is still present, clinicians should not continue to take re-assurance that the initial X-ray showed no abnormality. A further X-ray will often reveal the covert fracture or subluxation.

Missed diagnosis

Following injury, a patient who has a painful neck and a transient history of paraesthesia in all four limbs presents with a straightforward diagnosis. Similarly, the patient who is quadriparetic at the time of first assessment would appear to present no special diagnostic difficulty. However, unlikely as it may seem, there are examples of such paralysed patients not being diagnosed or managed appropriately. The reasons behind missed diagnoses include the following:

• History and neurological symptoms are not given an appropriate level of credibility and/or cervical spine trauma is not considered (e.g. in an inebriated patient).
• Diagnosis of an anxiety/hysterical/ manipulative psychological condition outwardly manifest by apparent limb paralysis (i.e. ‘hysterical paralysis’).
• Disbelief on the part of the clinicians, most often junior staff, and perhaps a ‘mind set’ which precludes objective assessment.
• Consideration of arcane neurological diagnoses in place of the more common diagnosis of spinal trauma.
• Inadequate or inappropriately interpreted radiology. General advice is a lateral X-ray of the cervical spine including all seven vertebrae if possible, supplemented with other imaging (CT) as necessary. Interpretation of lateral cervical spine X-rays, open mouth views of the odontoid process and sagittal reconstructions of computerised tomography is not easy and there is no substitute for obtaining a senior experienced opinion.
• Patient affected by alcohol, prescribed medication or illegal substances. The presence of a significant head injury will also preclude a useful history being obtained from the patient. Clinicians may have to rely on objective witness information as indication of the risk of a spinal injury. Screening X-rays/imaging are often the best source of objective information in such situations.
• Other injuries and pressure to ‘clear’ the cervical spine may distract from appropriate and thorough assessment of the spine and the need to re-assess if symptoms persist.

Risk reduction

• Do not entertain an initial diagnosis of hysterical or psychological paralysis.
• A history of transient neurological symptoms deserves a high level of credibility, particularly in the absence of objective neurological signs.
• The most useful diagnostic investigation is a good quality lateral cervical spine X-ray supplemented by multi-slice or spiral CT, particularly with sagittal reconstructions.
• Get a senior and/or an experienced opinion on the X-ray and imaging.
• Repeat the lateral X-ray if the patient continues to complain of neck pain a week later, especially in situations where the initial X-ray was considered normal.
• If uncertainty persists despite investigations, manage the patient for cervical spine injury and seek senior/experienced opinion. _ Specialist spinal injury services are available for discussion and advice.

 Mr Robin Johnston is a spinal consultant neurosurgeon at the National Spinal Injuries Unit in Glasgow