Clearance of the C-spine in the Unconscious Patient

Created on Tue, 06/30/2015 - 22:03
Last updated on Fri, 04/28/2017 - 17:55

Given that this is a common and practical ICU problem, the college have wisely included it among their SAQs - Question 10 from the second paper of 2008 asks the candidate to "Outline  and justify your approach to “clearing” the cervical spine in an adult multi-trauma patient with a severe closed head injury".

Since this question (written in 2008),

A synthesis of the abovelisted sources can be attempted, and rendered into this brief summary:

A normal result of a high-quality CT is enough to remove the collar.

Let us discuss this statement.

Clinical criteria:

Ch.78 from Oh's Manual (Spinal injuries by Sumesh Arora and Oliver J Flower) make mention of the NEXUS criteria and the Canadian C-spine rules. Even though everybody is already well aware of them, they are reproduced below largely as a reference for the forgetful author:

Clinical C-spine Clearance Criteria

The NEXUS criteria

The C-spine CT is not required if there is :

• no posterior midline cervical spine tenderness
• no evidence of intoxication
• a normal level of alertness
• no focal neurological deficit
• no painful distracting injuries.

Objections
  • "an alert level of conscious-ness sufficient to allow three-object recall at 5 minutes" is required.
  • Not even the odour of alcohol is permitted.
  • "Distracting injury" is a fairly subjective criterion.

The Canadian Rules

The C-spine CT is not required if :

• The patient is under 65 years of age

• The mechanism was not "dangerous"
• There is no paraesthesia in the extremities

AND:
• The mechanism permits safe ROM assessment

AND
• The patient is able to painlessly rotate their head 45°

 


Sensitivity: 99.6% for significant injuries

Specificity: 12.9%.

Sensitivity: 100% for significant injuries

Specificity: 45%.

Flower and Arora reference this NEJM article from 2003 as a source for their discussion of the various C-spine rules. It is therefore probably worth reading. However, before the time-poor candidate commits themselves to a thorough exploration of the C-spine controversy, it would be important to mention that emergency departments routinely pan-scan their multitrauma patients, and the C-spine ends up getting caught in the radiation beam because "while you're there" and "that injury looks distracting" and "he's drunk and crazed with meth and we intubated him". So, for the intensivist, the question is rarely "does this patient need a CT", and frequently "when can we take the collar off".

Disadvantages of being in a C-spine collar

There are certain problems with being an immobile trauma vicitim trapped inside a stiff neck collar, with restrictions on how you can be turned for routine care, and how your torso can be positioned.

A 2004 review by Morris and McCoy (quoted in Oh's Manual) presents a list of disadvantages as Figure 1, which is summarised below with some modification:

Problems associated with prolonged C-spine immobilisation

  • Pressure areas under the collar
    • Source of sepsis
    • Need for skin grafts
    • Increased hospital stay
  • Increased intracranial pressure
  • Airway is made more difficult by in-line stabilisation
  • Central venous access is made more difficult (IJ is out of bounds)
  • Oral care is made more difficult, increasing the risk of VAP
  • Nutrition is affected:
    • Gastroparesis and ileus results from prolonged immobility
    • Aspiration risk is increased by supine position
  • Physiotherapy is delayed or impossible
  • A greater risk of DVT/PE results from prolonged immobility
  • A minimum of 4 nursing staff are required to turn the patient.

None of these issues are going to sound surprising. Perhaps the reason these problems are neglected is that missed C-spine injuries are easy substrate for big public medicolegal spectacle, while a series of non-sexy complications like DVTs and bedsores are much less attractive to the media.

The Australian experience: when can we take the collar off?

According to a 2003 article, back then we didn't have a good standard way of doing this, and nobody was sure whether this was causing people harm. Lien Jaques and Powell lament:

"There is no standardised approach to the clearance of the cervical spine in intubated trauma patients in Australian intensive care units. In addition, morbidity from current practices and the true incidence of cervical spine injuries remains unknown."

So, in 2005 Cooper and Ackland published a summary which was good enough for the college to include on their website. In it, they discuss the evidence-based protocol they use at The Alfred. This cannot be a terrible protocol to follow, as it has been used as the source for at least one fellowship exam question. The specific feature of this is the simplicity of the algorithm they use for the unconscious patient. If the CT is normal, they clear the C-spine. Simple as that.

However, bold all-caps writing across their flowchart recommends that removing the collar in this context is a CONSULTANT-SUPPORTED DECISION, which I interpret as a warning. Any trainee clearing the C-spine from CT all by themselves will find themselves medicolegally exposed; more so if they aren't actually practicing at the Alfred. The reason for this is highlighted succinctly by the 2015 EAST guidelines: "the use of this approach may result in a nonzero rate of neurologic deterioration".

The implication, of course, is that in pursuit of a "zero rate" one ends up generating a nonzero rate of complications due to prolonged immobilisation, repeated scan transfers, unnecessary treatments and misguided specialist referrals.

The value of the trauma series CT in excluding spinal injury

  • It picks up 97% of bony injuries
  • It picks up 86% of subluxation injuries
  • It misses 75% of ligamenous injuries
  • It misses 100% (!!) of spinal cord injuries

However, a recent (2010) prospective study has concluded that for all its disadvantages, the CT picks up 99.75% of clinically significant spinal cord injuries. Yes, in other studies MRI found all sorts of extra ligamentous injuries whcih the CT had missed, but none of these were clinically significant, so why delay removing the collar?

When is it appropriate to use MRI to image the C-spine

There are a few features which would prompt you to order an MRI:

  • Signs or symptoms of spinal cord injury
  • The CT suggests there is ligamentous injury (or injury to the disc)

The reluctance of guideline-makers to greater integration of MRI into guidelines stems from the expense and poor availability of MRI, and from the risk of MRI transfer for the severely injured multi-trauma patient. Additionally, MRI can have a rate of false positives as high as 40%, resulting in the development of a large chronically C-collared population. If you are going to do it, then you should do it reasonably soon: after 72 hours, the gradual decrease in ligamentous oedema may increase the false-negative rate.

Is there any role for flexion-extension C-spine views

In this enlighetend age of iPhones and high-resolution helical CT scanners and whatnot, the humble flexion-extension C-spine film has fallen into disuse. So much has it become surpassed in diagnostic value, that some call for its immediate shamed expulsion from current C-spine management protocols. This view is supported by evidence. A 2013 systematic review of many heterogeneous studies has concluded that wherever CT and MRI are available, the value of this practice is minimal.

 

References

The Alfred Spinal Clearance Protocol

Chapter 78 (pp. 795) Spinal injuries by Sumesh Arora and Oliver J Flower

Lien, D., T. Jacques, and K. Powell. "Cervical spine clearance in Australian intensive care units." Critical Care and Resuscitation 5.2 (2003): 91.

Cooper, D. J., and H. M. Ackland. "Clearing the cervical spine in unconscious head injured patients-the evidence." Critical Care and Resuscitation 7.3 (2005): 181.

Hennessy, Deirdre, et al. "Cervical spine clearance in obtunded blunt trauma patients: a prospective study." The Journal of Trauma and Acute Care Surgery68.3 (2010): 576-582.

Como, John J., et al. "Is magnetic resonance imaging essential in clearing the cervical spine in obtunded patients with blunt trauma?." Journal of Trauma-Injury, Infection, and Critical Care 63.3 (2007): 544-549.

Tran, Baotram, Jonathan M. Saxe, and Akpofure Peter Ekeh. "Are flexion extension films necessary for cervical spine clearance in patients with neck pain after negative cervical CT scan?." Journal of Surgical Research 184.1 (2013): 411-413.

Sierink, J. C., et al. "Systematic review of flexion/extension radiography of the cervical spine in trauma patients." European journal of radiology 82.6 (2013): 974-981.

Patel, Mayur B., et al. "Cervical spine collar clearance in the obtunded adult blunt trauma patient: A systematic review and practice management guideline from the Eastern Association for the Surgery of Trauma." Journal of Trauma and Acute Care Surgery 78.2 (2015): 430-441.

Stiell, Ian G., et al. "The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma." New England Journal of Medicine 349.26 (2003): 2510-2518.

Morris, C. G. T., and E. McCoy. "Clearing the cervical spine in unconscious polytrauma victims, balancing risks and effective screening." Anaesthesia 59.5 (2004): 464-482.

Richards, Paula J. "Cervical spine clearance: a review." Injury 36.2 (2005): 248-269.