What do we do when Canadian C-spine rules fail?

What do we do when Canadian C-spine rules fail? A Medical Student Clinical Pearl



Christine Crain (She/Her), CC3
Dalhousie Medicine MD Candidate, Class of 2022

Reviewed by Dr. Mark McGraw

Copedited by Dr. Mandy Peach

Relevant Cases:

First, 7-year-old male presents to the ED by EMS having heard a “pop” in his neck followed by extreme pain in his neck and shooting pain down his left arm while playing with his father. He was feeling much better on arrival but was put on C-spine precautions.

Second, 76-year-old male presents via ambulance after being found down with an unwitnessed fall in a parking lot. He had obvious head trauma with a large supraorbital hematoma and arrived in a C-collar.

Third, 52-year-old gentleman with a history of partial C-spine transection arrives via EMS after being found down and inebriated by his PSW after attempting to transfer himself from his chair to his bed. Patient states he suspects he was down for about hours and that his previously strong leg now feels heavier and weaker.


The Canadian C-spine Rules have excellent sensitivity (90% to 100%)1 but have only been validated for those between the ages of 16-65. As well, any red flag symptoms, such as paresthesias, a dangerous mechanism, or intoxication, then these rules are not validated

Figure 1: Canadian C-Spine Rules. Diagram has been re-designed by the BoringEM.org team for clarity.

So, what do you do instead? In the first case, there are NEXUS rules with a sensitivity of 100% and a negative predictive value also at 100%. These are the same rules used for the adult population, but, where being under age 16 is an exclusion criterion in the Canadian rules, the NEXUS rules have been validated in the paediatric population as well2.

Figure 2: NEXUS C-Spine Rules. Retrieved from MDCalc.

What about Geriatrics?  They tend to be more on the fragile side due to conditions like osteopenia or osteoporosis and injuries or trauma may be further complicated by medications like blood thinners, because of this, these patients are considered high risk and should automatically receive imaging. Luckily, the NEXUS decision rule has also been validated in the geriatric population3. However, a caveat is required around what is meant by “altered level of consciousness”. This is something that can be hard to know in the Emergency Department without gaining collateral information. Altered Mentation is the hallmark of many degenerative brain diseases such as Alzheimer’s which may affect level of orientation. So, while the NEXUS criteria are validated in the Geriatric population, it’s important to gather collateral information on baseline mentation before performing imaging based only on altered level of consciousness.

Finally, in the situation where there is intoxication, the level of suspicion in these cases will be dictated more by mechanism and other associated injuries. The Canadian C-Spine rules can be used in patients who are intoxicated if the patients are alert and cooperative. However, in the situation with known vertebral disease, as in our third case, imaging will be done more based on new deficits, objective or subjective.

Case Resolutions:

In the first attached case, per the NEXUS rules, our patient didn’t need imaging. However, in the paediatric population the patient is not the only concern. The patient’s father was beside himself, thinking this was his fault as it happened while they were playing. Therapeutic radiography was used to put the father at ease. In this case, while there were no indications for imaging, there was an increased intervertebral space anteriorly at C7-8, which may have been consistent with an Anterior ligament rupture. More imaging was scheduled for the next day, and the patient was sent home with a collar on until he could be cleared via MRI.

For our second patient, he was altered on arrival with a GCS of 13, with deterioration on route reported by EMS. Additionally, he was on a blood thinner, so there was an increased risk for an intracranial bleed. He was sent for emergent CT, which showed a Type 2 Odontoid fracture. He was admitted to Neurosurgery.

Figure 3: Case courtesy of Dr Mohammad Taghi Niknejad, Radiopaedia.org, rID: 21310

In our final C-spine case, due to the subjective new deficit in the patient’s left leg, C-spine CT and thoracolumbar radiography were used to compare to previous imaging, many of which were available due to the recency of his injury. There was no evidence of any new injury on imaging, so the patient was observed doing a gentle range of his neck which produced no pain or other symptoms. His C-collar was removed, and he was discharged home to the care of his PSW.


It’s important to remember the limitations of tools we use regularly. The excellent sensitivity of the Canadian C-Spine rules makes it a very appealing tool to rely on; however, it’s important to remember how limited the population that the tool applies to. While other tools may help to fill the gaps, as the NEXUS rules do, sometimes these tools are hard to remember when you use them less often.

Hopefully by outlining and reminding you of the limitations, I will have helped you remember the other tools that are available to us in the Emergency Department in these situations.




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