What is a C Collar?
They come in a couple of different flavors, but the two extremes are hard and soft collars. The primary function of C Collars is to immobilize the C spine. Hard collars provide more immobilization and restriction of ROM compared to their soft brethren, but are generally more uncomfortable for patients.
Why use a C Collar?
C Collars are placed to protect the spinal cord from the possibility of secondary injury in the unstable cervical spine. The theoretical risk is worsening an unstable fracture, and potentially causing devastating neurological injury.
When to use a C Collar? Who should be in a C Collar?
Following trauma, early immobilization of the cervical spine can be crucial if c-spine injury is suspected. This can be obvious in patients involved in MVA, falls, and assaults to the head or neck. On history and physical, the patient may be complaining of sensation changes, neck, and back pain. But cervical injury may not be so obvious in the patient found down and unresponsive, who cannot communicate what happened to them, and may have had signs of a recent fall and possible C spine injury. C-collars are often placed on these patients too.
Protection of the C spine is considered so important, that a rigid C collar placement is reflexive in both the in and out of hospital environment. It's built into ATLS protocols. In many EMS protocols, if a patient is complaining of neck pain or any neurological symptom after trauma, they've bought themselves a C Collar.
This all sounds great....but then why is there debate around C-Collars?
The potential harm of C Collars:
C Collars are not benign interventions. The long term changes include muscular, bone, and tendon atrophy, but what about in the short term? Hard collars, like the C collars we place in the ED for our trauma patients, are associated with pain, breathing restriction, tissue ischemia, increase aspiration events, and adds barriers to medical care, including maintaining C spine when moving, exposing, and cleaning the patient. And that's only talking about the C collar in a vacuum: C Collars are notorious for hiding extent of trauma, such as soft tissue swelling and more commonly, bleeding of the occiput and neck. They also increase ICP- Stone et al. demonstrated that C collars increase ICP in healthy volunteers placed in C Collars, potentially worsening intracranial injury. Additional studies, like that of Kolb et al, found increased ICP measured by CSF pressure obtained through LP in a group wearing a c collar compared to a group that didn't.
What else does the literature say?
A lot of the benefits associated with C Collars are theoretical. Do they actually help and do what they're supposed to do?
Here's the problem with the existing literature: There are no prospective studies comparing an experimental C collar group with a no collar control group. And thus, a lot of research on C spine injury and c collars are done on cadavers and in analogous studies.
Some studies looked at whether C collars are even able to immobilize the spine. One study looked at "lightly embalmed" cadavers with an induced C5-6 instability injury, and then put on different types of C collar. They tested for motion using EMG sensors, and tested all planes of cervical motion. They found no significant difference in motion between the C spine groups and the no c collar group. Another cadaver study with induced c spine instability even found increased motion in axial and cranial-caudal planes in a rigid C collar group compared to no c collar group, possibly through the creation of "pivot points" from where the collar meets the TMJ and shoulders.
What about the possibility of preventing secondary injury? Other studies (involving mostly cadavers, again) has shown that a considerable amount of force is required to fracture the spine, and that subsequent, low energy forces from patient's moving their neck is unlikely to cause additional spinal cord injury. Additionally, these and similar studies suggest that an unstable fracture existing without already devastating neurological injury is rare. Furthermore, it is also suggested in a retrospective study looking at neurological outcome between the USA (where we routinely immobilize with C collars) vs Malaysia (a country that does not routinely immobilize patients) and found that less neurological disability occurred in the unimmobilized group, suggesting that there may even be the potential of neurological harm. Obviously, a lot of this research is not perfect but it certainly does not favor the absolute benefit of using C collars routinely.
What should we do?
The real question at the end of the day. Placing C Collars is still the standard of care, though additional research may one day point us away from reflexively using it, and perhaps protocols detailing its use in trauma may become more sparing. In the meantime, for our trauma patients, we can decrease the time sensitive risks associated with these devices by clearing them as soon as we can, as we always have. This research at least opens my eyes to the potential of C collars causing harm, and that one day what has been drilled into my head regarding trauma management may not always be the case.
Thanks for sticking around till the end!
-SD
Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481593/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684205/
http://www.emdocs.net/cervical-collars-for-c-spine-trauma-the-facts/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2751736/
https://pubmed.ncbi.nlm.nih.gov/511875/
https://pubmed.ncbi.nlm.nih.gov/22962052/