Highlights:
The Scenario
The Review
What It Means for You
The Scenario
Medic 3 responds with the fire department to a reported motor-vehicle collision at a busy intersection. Two patients are present on the scene; both were front seat passengers in a car versus telephone pole collision. The seat-belted driver is walking around, has no complaints, and no evidence of traumatic injury. The second patient was not wearing his seat belt at the time of the impact and is sitting in the vehicle.
Inspection of the vehicle reveals a broken area in the windshield that approximates the shape and size of the patient’s head. The patient is a male, age 42, who is conscious and alert with multiple lacerations on the forehead. Bleeding appears controlled. The patient denies loss of consciousness, complains of mild neck pain, but is able to move all extremities. The remainder of the physical exam is unremarkable.
One of the firefighters enters the back seat of the vehicle and maintains the patient’s head in a neutral position with manual in-line stabilization. The paramedic measures and selects an appropriately sized extrication collar and applies it to the patient’s neck. The rescue team successfully removes the patient from the vehicle, secures him to a long backboard, and places him in the ambulance.
The patient remains conscious and alert with a Glasgow Coma Score of 15. The patient’s blood pressure is 130/86 mmHg, the pulse is 90 bpm, and the respiratory rate is 14 bpm. The head-to-toe exam is unremarkable for trauma except for the lacerations to the forehead. En route to the hospital, the patient begins complaining of a tingling sensation in the arms and legs and increased discomfort in the neck.
Emergency department X-rays do not discover evidence of cervical fractures, although the patient continues to have worsening paresthesia. Magnetic resonance imaging (MRI) reveals significant disruption of the upper cervical ligaments and an atlanto-occipital distraction.
Back at the station, the medics wonder if application of the extrication collar may have made the situation worse, since the tingling only began after spinal motion restrictions occurred. The shift duty officer assures them that they performed exactly as protocol dictated and that without the collar, the injury could have been much worse.
The Review
Article: Ben-Galim, P., Dreiangel, N., Mattox, K. L., Reitman, C. A., Kalantar, S. B., & Hipp, J. A. (2010). Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury. The Journal of Trauma Injury, Infection, and Critical Care, [Epub ahead of print].
Using fresh whole human cadavers, investigators from the Spine Research Laboratory at the Baylor College of Medicine in Houston examined the effects that spinal motion restriction devices have on a destabilized cervical spine (Ben-Galim, Dreiangel, Mattox, Reitman, Kalantar, & Hipp, 2010).
None of the cadavers had previous cervical spine injuries or abnormalities. The research team placed the cadavers in a refrigerated state until the effects of rigor mortis subsided and then warmed the specimens to room temperature. Previous investigations demonstrated a high correlation in vertebral movement between room temperature whole cadavers and asymptomatic live humans (Brown, Reitman, Nguyen, & Hipp, 2005; Subramanian, Reitman, Nguyen, & Hipp, 2007).
In this study, researchers focused on the first and second cervical vertebrae. The first cervical vertebra (C1, otherwise known as the atlas) forms a ring of bone upon which the skull (more specifically, the occiput) rests (Marieb, 1989).
The atlas rests on the axis, which is the second cervical vertebra (C2). A small bony protuberance called the odontoid extends from the body of the axis into the opening of the atlas alongside the spinal cord. Under normal conditions, connecting ligaments and other tissues limit movement of these vertebrae.
However, damage to those ligaments, as might occur during traumatic injury, permits abnormal movement or allows the skull to separate from the spinal column, a condition known as internal decapitation (Brown, Reitman, Nguyen, & Hipp, 2005). Most patients who suffer this type of dissociative injury die almost instantaneously (Bucholz & Burkhead, 1979), although the literature describes dozens of survivors (Anderson, Towns, & Chiverton, 2006).
Two previous investigations of fatal atlanto-occipital injuries describe complete disruptions of the supporting ligaments, with and without associated fractures (Bucholz & Burkhead, 1979) (Ben-Galim, Sibai, Hipp, Heggeness, & Reitman, 2008).
For this investigation, the researchers replicated this type of upper cervical spine injury by leaving the muscles intact but surgically transecting the supporting ligaments. In addition, the team fractured the odontoid at its base.
Using a standard EMS spinal immobilization protocol that included manual stabilization, the team applied a commercially available and properly sized extrication collar. Researchers obtained before-collar and after-collar fluoroscopic images in the first four cadavers. The five remaining cadavers received before and after computed tomography (CT) scans. Researchers then measured the degree of distraction or separation between C1 and C2.
In every cadaver, proper application of an extrication collar resulted in abnormal separation between these two vertebrae. The mean of the average distance was 7.3 mm with a standard deviation of 4.0 mm. In effect, application of an extrication collar in these cadavers resulted in separation of the head from the spinal column.
What It Means for You
There are approximately 12,000 new cases of spinal cord injury in the United States every year (National Spinal Cord Injury Statistical Center, 2010). The most common cause is motor-vehicle collisions, which account for almost half of the injuries. Patients who survive often face devastating physical immobility and a lifetime of related health issues.
Since the birth of the modern emergency medical service system, training programs stressed the need for proper application of cervical collars to safeguard against the possibility of further damage during movement to the hospital.
This direction is in spite of the absence of proven benefit from spinal immobilization (Domeier, Frederiksen, & Welch, K. 2005). Quite to the contrary, researchers have demonstrated that rigid spinal immobilization procedures can result in tissue necrosis (Cordel, Hollinsworth, Olinger, Stroman, & Nelson, 1995), increased intracranial pressure (Dunham, Brocker, Collier, & Gemme, 2008), reduced pulmonary function (Bauer & Kowalski, 1988), and even death (Papadopoulos, Chakraborty, Waldron, & Bell, 1999).
Although the results of this study add to the collective knowledge about the harm that cervical collars can create, one must be careful about making false assumptions about the results.
Extrapolating the results from an investigation involving specific research conditions to a much larger population involves a concept known as generalizability. Some conclusions are easily generalizable across a broad spectrum of conditions while others are not.
For example, suppose an observer (or researcher) watched cars travelling on a road for a period of a month. At the end of the study period, the observer saw 5000 people driving on the right-hand side of the road. The observer might conclude drivers operate their vehicles in that right hand lane.
However, those results are not generalizable to all drivers everywhere. We are all aware that drivers in some other countries operate their vehicles on the left side of the roadway.
The cervical collar study examined only one specific type of injury, namely atlanto-occipital dissociative injuries. In the general population, these injuries are rare and almost uniformly fatal at the moment of impact (Cooper, Gross, Lacey, Traven, Mirza, & Arbabi, 2010).
Motor vehicle collisions and falls can produce many other types of cervical injuries. No convincing data demonstrates similar degrees of distraction in other cervical injuries as the result of rigid extrication collar application.
Therefore, one cannot reliably conclude that application of cervical collars will produce dangerous spinal cord stretching in ALL patients with cervical injuries.
Another limitation that also addresses the issue of generalizability is in this study’s use of cadavers. Cadavers lack muscle tone. Normal muscle tone provides a considerable degree of stabilization in upper cervical spine injuries (Ben-Galim, Sibai, Hipp, Heggeness, & Reitman, 2008).
It is possible that this inherent stabilization limits the separation between C1 and C2 in conscious patients with this type of dissociation injury including those with extrication collars applied. However, it is reasonable to assume that the lack of muscle tone in cadavers mimics the reduced tone found in patients rendered unconscious from the trauma or from subsequent rapid sequence induction procedures.
Although the International Trauma Life Support guidelines warn against the prehospital application of in-line traction during stabilization procedures (Augustine, 2008), field application of cervical collars appears to produce distraction or stretching of the spinal column in some patients.
While this study does not mean that EMS should abandon the use of cervical collars, it does suggest the need for a reevaluation of the risks and benefits of the currently accepted practices for cervical spinal immobilization.
Medical directors must ensure that field providers utilize proper restraining techniques, including choosing appropriately sized collars. In addition to the dangerous distraction for some patients with normal use, cervical collars that are too large for the patient or those strapped too tightly around the neck may worsen distraction by pushing the head even farther away from the trunk (Ben-Galim, Sibai, Hipp, Heggeness, & Reitman, 2008).
Perhaps future research will lead to an evidence-based redesign of cervical collars or the realization that collars are no more effective than rolled-up blankets used decades ago.
References
Anderson, A. J., Towns, G. M., & Chiverton, N. (2006). Traumatic occipitocervical disruption: a new technique for stabilisation. Case report and literature review. Journal of Bone and Joint Surgery British Volume, 88, 1464-1468.
Augustine, J. J. (2008). Spinal trauma. In J. E. Campbell (Ed.), International trauma life support for prehospital care providers (6th ed., pp. 161-182). Upper Saddle River, NJ: Pearson Education.
Bauer, D. & Kowalski, R. (1988). Effect of spine immobilization devices on pulmonary function in the healthy nonsmoking man. Annals of Emergency Medicine, 17, 915-918.
Ben-Galim, P., Dreiangel, N., Mattox, K. L., Reitman, C. A., Kalantar, S. B., & Hipp, J. A. (2010). Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury. The Journal of Trauma Injury, Infection, and Critical Care, [Epub ahead of print].
Ben-Galim, P. J., Sibai, T. A., Hipp, J. A., Heggeness, M. H., & Reitman, C. A. (2008). Internal decapitation: survival after head to neck dissociation injuries. Spine, 33, 1744-1749.
Brown, T., Reitman, C. A., Nguyen, L., & Hipp, J. A. (2005). Intervertebral motion after incremental damage to the posterior structures of the cervical spine. Spine, 30, E503–E508.
Bucholz, R. W. & Burkhead, W. Z. (1979). The pathological anatomy of fatal atlantooccipital dislocations. Journal of Bone and Joint Surgery, 61, 248-250.
Cooper, Z., Gross, J. A., Lacey, M., Traven, N., Mirza, S. K., & Arbabi, S. (2010). Identifying survivors with traumatic craniocervical dissociation: A retrospective study. Journal of Surgical Research, 160, 3-8.
Cordel, W. H., Hollinsworth, J. C., Olinger, M. L., Stroman, S. J., & Nelson, D. R. (1995). Pain and tissue-interface pressures during spine-board immobilization. Annals of Emergency Medicine, 26, 31-36.
Domeier, R. M., Frederiksen, S. M., & Welch, K. (2005). Prospective performance assessment of an out-of-hospital protocol for selective spine immobilization using clinical spine clearance criteria. Annals of Emergency Medicine, 46, 123-131.
Dunham, C. M., Brocker, B. P., Collier, B. D., & Gemme, D. J. (2008). Risks associated with magnetic resonance imaging and cervical collar in comatose, blunt trauma patients with negative comprehensive cervical spine computed tomography and no apparent spinal deficit, Critical Care, 12. Retrieved May 17, 2010, from, http://ccforum.com/content/12/4/R89
Marieb, E. N. (1989). Human Anatomy and Physiology. Redwood City, CA: Benjamin/Cummings.
National Spinal Cord Injury Statistical Center. (2010). Spinal cord injury facts and figures at a glance. Retrieved May 16, 2010, from www.nscisc.uab.edu/public_content/pdf/Facts%20and%20Figures%20at%20a%20Glance%202010.pdf.
Papadopoulos, M. C., Chakraborty, A., Waldron, G., & Bell, B. A. (1999). Exacerbating cervical spine injury by applying a hard collar. British Medical Journal, 319, 171-172.
Subramanian, N., Reitman, C. A., Nguyen, L., & Hipp, J. A. (2007). Radiographic assessment and quantitative motion analysis of the cervical spine after serial sectioning of the anterior ligamentous structures. Spine, 32, 518-526.
The author has no financial interest, arrangement, or direct affiliation with any corporation that has a direct interest in the subject matter of this presentation, including manufacturer(s) of any products or provider(s) of services mentioned.
