Review of: Ben-Galim P, Dreiangel N, Mattox KL, et al. Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury. J Trauma. 2010;68(1). [Epub ahead of print]
Cervical collars (C-collars) are applied to a large population of trauma patients with the intent of protecting the cervical spine in the cases of suspected severe neck injury. Increased morbidity and mortality in the care of these patients leads the investigators to believe c-collar application may be harmful in some cases. The purpose of this investigation was to evaluate the mechanics and effects of applying a c-collar to patients with severe neck injuries.
The investigators looked specifically at the C1 and C2 vertebrae. By surgically destroying the ligaments and the membranes supporting these vertebral structures, but leaving muscular structure intact, the researchers attempted to recreate a dissociative, or separation, injury.
Nine human cadavers were used for the study. Cervical images of before and after c-collar administration were taken by X-ray, fluoroscopy and/or CT scan. Four patients had X-rays and fluoroscopy taken, and five had all three images taken. Investigators also used a standard EMS spinal immobilization protocol.
Substantial differences were found in the before and after images. On average, 7.3 mm of separation (+/- 4.0 mm) was found in C1 and C2 after the application of a c-collar. In essence, the c-collar effectively separated the head from the shoulders creating the gap between the two vertebrae.
The investigators conclude further research is necessary to understand the risks and benefits of c-collar application and stabilization of the cervical spine (c-spine) to avoid further complication or injury.
Medic Marshall and Dr. Wesley agree that this study is concerning and challenges the misperception that C-spine immobilization is without potential harmful effects.
Medic Marshall: Working in the tundra that is Minnesota, management of the trauma patient can be difficult at times. With harsh environmental factors to contend with, appropriately applying a C-collar and placing a patient on a backboard, particularly when they're wearing heavy winter clothing, can be next to impossible. In reality, we often slap a collar on and rapidly extricate. Not to mention, if your patient is that severely injured, you're more concerned about getting them the nearest hospital or Level 1 trauma center.
I do find the study has some flaws. First: Cadavers were used. The authors agree that this may or may not represent the typical patient with a severe C-spine injury. However, it's reasonable to assume it does correspond to the intubated patient following RSI.
Back in October, the Doc and I evaluated literature that showed that patients were better at maintaining their own stabilization without the use of a C-collar and that c-collar application led to significant rotational forces. There's additional literature indicating the patients with penetrating injuries to the neck have a higher mortality when a c-collar is applied.
Second: If the shearing forces were enough to create the injuries reproduced in the study, then wouldn't it suffice to say that damage to the spinal cord has already been done? If that's the case, some might wonder if the application of the C-collar worsens the spinal injury. I ll let the doc respond to that.
So what does the study mean to me? It really makes me wonder if we're causing more harm than good to some patients. Do I think we need to stop applying c-collars on these patients? I don't think so. Perhaps it s more an issue of the mechanics involved in the application. There's evidence that once a c-collar has been applied, it effectively immobilizes the C-spine, which the authors acknowledge. I agree with the authors. More research is needed to evaluate the risks and benefits of this procedure.
Doc Wesley: When I first reviewed this paper, I became worried that this study would do to C-collars what one of these authors' "research" long ago did to the MAST. The "dissociative injury" inflicted on these cadavers was one that, in most cases, would result in a complete spinal cord injury and would be fatal during the accompanying trauma. However, although this study was conducted on cadavers, I had the opportunity to speak with the author and view fluoroscopy images of a live patient with a high cervical injury. Although the collar was being applied, it was evident that the patient's skull was literally being lifted from the spinal column.
One of the authors (Peleg Ben-Galim, MD) has also noted that there doesn t have to be complete dissociative injury to have additional spinal cord trauma occur; he reported at a recent conference that it can also occur during treatment of what many providers currently term a "sprained neck," without accompanying cervical fractures.
As the images in the paper demonstrate, the degree of injury to the neck resulted in a significant ability to pull the head away from the shoulders. However, the authors assume that EMTs apply C-collars in a manner that produces this kind of neck extension.
The question to be answered is this: Is excessive neck extension occurring due to the way we instruct providers to apply the collar or is it being caused by the collar itself? EMS providers are trained (or are supposed to be trained) to apply the collar with the head in a neutral position and adjust the collar to fit the neck. Not the other way around. However, I've received far too many patients with poorly fitting collars, most with the chin portion riding up and over the chin.
The reality of the situation is that there's little evidence that the hard c-collars we currently use provide any more spinal immobilization than a soft foam collar and head blocks or other materials. These devices have not undergone rigorous scientific review with these types of injuries, and this study is the first to definitively show that they can cause harm in some instances.