Saturday, June 3, 2017

Spinal Injury - Initial Assessment



SCI must  be presumed until excluded.
Studies recorded missed injury rate as high as 33%. Delayed or missed diagnosis is usually attributed to failure to suspect an injury to the cervical spine, or to inadequate cervical spine radiology and incorrect interpretation of radiographs. An appropriate procedure for the evaluation of the potentially unstable spine must be robust and easy to implement, with a high sensitivity, given the potential importance of such injuries. It must also address the main issues raised by the modalities available for diagnosis.
For spinal trauma, the main concerns are which patients can be cleared by clinical exam alone, how many plain X-rays are necessary and when should additional imaging using Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) be used. An assessment for ligamentous injury in the absence of a fracture is also important, especially in unconscious patients who are unable to complain of neck pain or tenderness.
While it is tempting to focus on the cervical spine, it is important to assess and clear the entire spinal column. The thoracolumbar spine, while more protected, is at risk in major trauma and must be assessed both clinically and radiologically. Additionally, 5% of spinal injuries have a second, possibly non-adjacent, fracture elsewhere in the spine.
These pages discuss the initial assessment and management of the potentially spine injured patient. The actual protocol implemented at any given institution will depend on the expertise and facilities available. Where the required expertise or imaging are not available in a given institution, the protocol should encompass criteria for expeditious transfer of patients to specialist care.

Spinal Stabilization & Management



Spinal immobilization is a priority in multiple trauma,
spinal clearance is not.



Indications for spinal immobilization

Very few studies define the criteria used to decide who is at risk from cervical spine injury.
Blunt Injury All patients with sufficient mechanism of injury to lead to a spinal injury should be considered to have a spinal injury until proven otherwise. What constitutes 'sufficient mechanism' is undefined.
Penetrating Injury Gunshot wounds that have traversed the spinal column may produce unstable injuries and caution should be exercised. Gunshot wounds to the cranium alone are not associated with a risk of cervical spine trauma. It is not necessary to immobilize stab injuries. Spinal immobilization devices may interfere with the recognition and management of life-threatening conditions.

Techniques of immobilization and patient handling

The spine should be protected at all times during the management of the multiply injured patient. The ideal position is with the whole spine immobilised in a neutral position on a firm surface. This may be achieved manually or with a combination of semi-rigid cervical collar, side head supports and strapping. Strapping should be applied to the shoulders and pelvis as well as the head to prevent the neck becoming the centre of rotation of the body.

Prehospital

Manual spinal protection should be instituted immediately. The application of definitive immobilisation devices should not take precedence over life-saving procedures.
If the neck is not in the neutral position, an attempt should be made to achieve alignment. If the patient is awake and co-operative, they should actively move their neck into line. If unconscious or unable to co-operate this is done passively. If there is any pain, neurological deterioration or resistance to movement the procedure should be abandoned and the neck splinted in the current position.
Long spine (rescue) boards are valuable primarily for extrication from vehicles. Repeated transfers to and from the board may compromise spinal protection and induce a significant amount of spinal movement. Patients may also be transferred on a scoop stretcher and/or vacuum mattress. There is little place for the short spine board or spinal extrication devices in the prehospital environment.

In-hospital

The spine board should be removed as soon as possible once the patient is on a firm trolley. Prolonged use of spine boards can rapidly lead to pressure injuries. Full immobilisation should be maintained. Manual protection should be reinstated if restraints have to be removed for examination or procedures (eg. intubation).
The log-roll is the standard manoeuvre to allow examination of the back and transfer on and off back boards. Four people are required, one holding the head and coordinating the roll, and three to roll the chest, pelvis and limbs. The number and degree of rolls should be kept to an absolute minimum. Rigid transfer slides (eg. Patslide) are useful for transferring the patient from one surface to another (eg CT scanner, operating table).
Patients who are agitated or restless due to shock, hypoxia, head injury or intoxication may be impossible to immobilise adequately. Forced restraints or manual fixation of the head may risk further injury to the spine. It may be necessary to remove immobilisation devices and allow the patient to move unhindered.
Anaesthesia may be necessary to allow adequate diagnosis and therapy. Intubation of the trauma victim is best achieved via rapid sequence induction of anaesthesia and orotracheal intubation, though the technique used should ultimately depend on the skills of the operator. The collar should be removed and manual, in-line protection re-instituted for the manoeuvre. The routine use of a gum elastic bougie is recommended, minimising cervical movement by allowing intubation with minimal visualisation of the larynx.

Transfer to Secondary Units

Patients may require transfer to other units for definitive care of other injuries such as head or pelvic trauma. There should be no unnecessary delays in the transport of these patients. Transfer should not wait for unnecessary diagnostic procedures that will not alter management. This includes radiological imaging of the spine.
The spine should be immobilised and protected for the transfer. Split-scoop stretchers and vacuum mattresses are more appropriate for transfer than rigid spinal (rescue) boards, which should be reserved for primary extrication from vehicles, rather than as devices for transporting patients.

Spinal Clearance

  1. Spinal immobilisation is a priority in multiple trauma, spinal clearance is not.
  2. The spine should be assessed and cleared when appropriate, given the injury characteristics and physiological state.
  3. Imaging the spine does not take precedence over life-saving diagnostic and therapeutic procedures.

Clinical clearance of Cervical Spine Injury

Numerous large prospective studies have described the large cost and low yield of the indiscriminate use of cervical spine radiology in trauma patients. Although there are case reports of bony or ligamentous injuries in asymptomatic patients, no asymptomatic patient in the literature has had an unstable cervical spine fracture or suffered neurological deterioration due to the injury. There is no conclusive evidence in the literature that supports clinical clearance of the spine in the prehospital environment. There is enough variation between prehospital and in-hospital assessments to recommend that prehospital removal of spinal immobilisation be avoided. Mechanism of injury alone does not determine the need for radiological investigation.
The cervical spine may be cleared clinically if the following preconditions are met:
  • Fully alert and orientated
  • No head injury
  • No drugs or alcohol
  • No neck pain
  • No abnormal neurology
  • No significant other 'distracting' injury (another injury which may 'distract' the patient from complaining about a possible spinal injury).
Provided these preconditions are met, the neck may then be examined. If there is no bruising or deformity, no tenderness and a pain free range of active movements, the cervical spine can be cleared. Radiographic studies of the cervical spine are not indicated.

Conscious, Symptomatic Patients

  1. Radiological evaluation of the cervical spine is indicated for all patients who do not meet the criteria for clinical clearance as described above.
  2. Imaging studies should be technically adequate and interpreted by experienced clinicians.

Plain Film Radiology

The standard 3 view plain film series is the lateral, antero-posterior and open-mouth view.
The lateral cervical spine film must include the base of the occiput and the top of the first thoracic vertebra. The lateral view alone is inadequate and will miss up to 15% of cervical spine injuries. The lower cervical spine may be difficult to examine and caudal traction on the arms should be used to improve visualisation. Repeated attempts at plain radiography are usually unsuccessful and waste time. If the lower cervical spine is not visualised a CT scan of the region is indicated. How to read the lateral cervical spine film.
The antero-posterior view must include the spinous processes of all the cervical vertebrae from C2 to T1.
The open-mouth view should visualise the lateral masses of C1 and the entire odontoid peg. Bite blocks may improve the open-mouth view. In the unconscious, intubated patient the open mouth view is inadequate and should be replaced by a CT scan from the occiput to C2.
The addition of two oblique views to the standard 3-view series does not increase the sensitivity of plain film evaluation. Some centres use two supine or trauma-oblique views to replace the antero-posterior view. These views can provide excellent visualisation of the posterior elements of the cervical spine and provide significantly more information than the antero-posterior view. Lateral

CT Scanning

Thin-cut (2mm) axial CT scanning on specific bone windows, with sagittal and coronal reconstruction should be used to evaluate abnormal, suspicious or poorly visualised areas on plain radiology. With technically adequate studies and experienced interpretation, the combination of plain radiology and directed CT scanning provides a false negative rate of less than 0.1%. The scan should include the entire vertebral body above and below the region of interest, as these must be undamaged for subsequent internal fixation.

Assessment of soft tissue injury in the awake patient

The patient with normal radiological evaluation as described above who has persistent symptoms requires an evaluation of soft tissue injury with static flexion and extension imaging of the neck at the extremes of the active range of motion. Pure disc or ligamentous disruption can produced unstable cervical spine injuries and will usually be detected by such imaging. The movements are safe provided the patient performs them actively and halts if there is an increase in pain or neurological symptoms.

Magnetic Resonance Imaging

All patients with an abnormal neurological examination should be evaluated in a specialist unit and have an MRI scan of the spine. Patients who report transient neurological symptoms (the 'stinger' or 'burner') but who have a normal exam should also undergo an MRI assessment of their spinal cord.

Unconscious, Intubated Patients

  1. The odontoid view is unreliable in intubated patients.
  2. Clinical examination is impossible in the unconscious patient.
  3. Plain film radiology cannot exclude ligamentous instability.
The standard radiological examination of the cervical spine in the unconscious, intubated patient is :
  • Lateral cervical spine film
  • Antero-posterior cervical spine film
  • CT scan of occiput - C3
The open-mouth odontoid radiograph is inadequate in intubated patients and will miss up to 17% of injuries to the upper cervical spine.
Thin-cut (2mm) axial CT scanning on specific bone windows, with sagittal and coronal reconstruction should be used to evaluate abnormal, suspicious or poorly visualised areas on plain radiology. With technically adequate studies and experienced interpretation, the combination of plain radiology and directed CT scanning provides a false negative rate of less than 0.1%. The scan should include the entire vertebral body above and below the region of interest, as these must be undamaged for subsequent internal fixation.

Ligamentous Instability

Clearance of the spine in unconscious patients is limited by the lack of clinical information. The incidence of unstable spinal injury in adult, intubated trauma patients is around 10.2%. The incidence of unstable, occult spinal trauma (not visible on plain films is around 2.5%. The options for full clearance of cervical spine injury are:
  • Continue precautions until fully conscious
  • Magnetic Resonance Imaging
  • Dynamic Flexion-Extension Fluoroscopy
  • CT Scan whole cervical spine

Continue spinal precautions until fully conscious.

Where the patient is expected to regain full consciousness in the following 24-48 hours, patients can be nursed with full spinal precuations. Once the patient has returned to full consciousness, clinical examination can exclude significant ligamentous injury.
Prolonged spinal immobilisation in critically ill patients leads to decubitus ulcers and deep venous thromboses while compromising nursing care, respiratory support and the management of traumatic brain injury.
A semi-rigid collar is not necessary in the adequately sedated, ventilated patient, and may increase intracranial pressure in patients with traumatic brain injury.

Magnetic Resonance Imaging

MRI is extremely sensitive at detecting soft tissue injuries without stressing the cervical spine. However the significance of such injuries with regards to the clinical stability of the spine is not clear, and the number of false positive examinations is high. MRI of ventilated patients is a significant undertaking requiring special non-ferromagnetic equipment. However the increasing use of MRI for critically ill patients is making this equipment cheaper and more widely available. Possibly because of the difficulties associated with undertaking routine MRI scans in these patients, there have been few good studies on the use of MRI in clearing the cervical spine in unconscious patients.

Dynamic Flexion-Extension Fluoroscopy

Fluoroscopy Passive dynamic flexion/extension stressing of the cervical spine, performed by an experienced clinician, should reveal most significant ligamentous injuries. Several centres have reported their results, and some guidelines give primary support to the use of dynamic fluoroscopy in clearance of the spine in unconscious patients.
However, there are significant difficulties in performing flexion/extension imaging routinely on the intensive care unit, and many spinal surgeons are unwilling to perform the study due to safety & resource implications. Of 625 patients currently reported in the literature, dynamic fluoroscopy has a sensitivity of 92.3% and specificity of 98.8%. Two cases of neurological deterioration during the study have been reported, including one complete quadriplegia.

CT Scan whole Cervical Spine

In recent years, the concept of full cervical spine CT for assessment of spinal injury has emerged. There are several studies that have demonstrated the robustness of the full CT scan, with sagittal and coronal reconstructions, for the exclusion of significant spinal injury. Widening, slippage or rotational abnormalities of the cervical vertebrae suggest soft tissue injury. An absence of such signs appears to exclude significant instability. Abnormal findings on the CT scan are evaluated by a spinal surgeon and additional modalities, such as MRI, can be employed. No study has missed a cervical spine injury, and no study has identified an injury on plain films that was not apparent on the CT scan.
Helical or multislice CT scanning from the Occiput to T1 is performed at 2-3mm collimation and 1.5mm pitch. Sagittal and coronal reconstructions are must be closely examined for indications of ligamentous instability. When whole cervical spine CT scanning is performed, the antero-posterior plain film becomes redundant.

Thoracic & Lumbar Spine Injury

  1. Thoracolumbar spine imaging is indicated if there is pain, bruising, swelling, deformity or abnormal neurology attributable to the thoracic or lumbar spinal regions.
  2. The presence of a fracture anywhere in the spine mandates full spinal imaging.
  3. Unconscious patients who cannot be assessed clinically also require radiological clearance of the whole spine.
The standard imaging for the thoracic and lumbar spine are antero-posterior and lateral radiographs.
CT scanning is carried out for any abnormal, suspicious or inadequately visualised ares. The scan should include the entire vertebral body above and below the level of injury, as these need to be uninjured if used for operative fixation.
Patients with abnormal neurology attributable to the thoracic or lumbar spine should undergo an MRI scan to visualise the spinal cord.

Paediatric Spine Injury

  1. Spinal evaluation in the paediatric population is similar to those in adults.
  2. Clinical and radiological evaluation of the immature anatomy requires particular care, with attention paid to X-ray variants.
  3. Spinal cord injury without radiographic plain film abnormality is more common in this age group and a thorough neurological examination is important.

Immobilization

Children have a disproportionately larger head size than adults, and when supine on a firm surface will be in a position of slight flexion. This slight degree of flexion is rarely a problem, though it can give rise to difficulties in X-ray interpretation. This can be corrected by placing a folded towel or sheet under the patient's shoulders to bring the cervical spine into the neutral position.
It may be difficult to immobilize a child adequately. Distress and discomfort may require that manual in-line stabilization is used instead of a semi-rigid collar, blocks and tape. Collar sizing may be difficult and there are no collars that adequately fit infants aged 6 and below.

Clinical Clearance

Clinical clearance of the spine is less well established in the paediatric population. While the NEXUS study (Vicellio) has shown promise in this area, of 3065 patients there were only 4 cervical spine injuries in patients under 9 years of age, and none below 2 years old.

Radiology

The immature anatomy of the paediatric cervical spine requires some expertise and familiarity to interpret and to avoid missed injuries. Due to the paediatric patients' larger head size, pseudosubluxation of C2 on C3, and anterior translations may appear as injuries rather than as consequences of mild flexion.