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Canadian C-spine rule: the three questions and how they combine

The Canadian C-spine rule works through three questions in order after blunt trauma to the head or neck in an alert, stable adult. First, is there a high-risk factor (age 65 or older, a dangerous mechanism, or paresthesias in the arms or legs)? Second, is there a low-risk factor that allows the neck's range of motion to be assessed? Third, can the person actively rotate the neck 45 degrees to the left and right? Magent's calculator turns those answers into a single true/false result, called positive or negative on this page.

This page doesn't give disposition advice. It shows how the three questions combine and what each input means. What to do with the result depends on the clinical context.

Not a medical device. Not a diagnosis or dosing recommendation.

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What is the Canadian C-spine rule?

The Canadian C-spine rule (also called the Canadian cervical spine rule, CCR or the Stiell C-spine rule) is a clinical decision rule from Ian G. Stiell and colleagues, published in JAMA in 2001. It was built for "alert and stable trauma patients," the phrase in the paper's title.

The 2001 abstract says the rule "comprises 3 main questions." Unlike a points score, the questions are asked in a fixed order, and an earlier answer can end the process before the later questions are reached.

The Canadian C-spine rule logic

high_risk = age >= 65 OR dangerous_mechanism OR paresthesias_extremities

low_risk  = simple_rear_end_mvc OR sitting_in_ed OR ambulatory_since_injury
            OR delayed_neck_pain OR NOT midline_cspine_tenderness

if high_risk:          result = positive
elif not low_risk:     result = positive
else:                  result = positive if NOT able_to_rotate_45, otherwise negative

Exact expression the calculator uses:

xray indicated if any high-risk (age >= 65 or dangerous_mechanism or paresthesias_extremities); else if no low-risk allowing ROM (simple_rear_end_mvc or sitting_in_ed or ambulatory_since_injury or delayed_neck_pain or midline_cspine_tenderness false); else if not able_to_rotate_45

Question 1: any high-risk factor?

The 2001 abstract's first question asks whether any high-risk factor is present: "age >/=65 years, dangerous mechanism, or paresthesias in extremities." If any of the three is present, the result is positive and questions 2 and 3 aren't consulted.

InputMeaning
ageAge in years, 18 to 120. Age 65 or older is a high-risk factor; 64 isn't.
dangerous_mechanismA dangerous mechanism of injury, as assigned by the caller
paresthesias_extremitiesParesthesias (tingling or pins and needles) in the arms or legs

Magent's record lists these dangerous mechanisms: a fall from 3 feet or 5 stairs or higher; an axial load to the head; a high-speed motor vehicle collision (over 100 km/h), rollover or ejection; a motorized recreational vehicle; or a bicycle collision.

Question 2: any low-risk factor that allows range-of-motion assessment?

The abstract's second question asks about "any low-risk factor present that allows safe assessment of range of motion (ie, simple rear-end motor vehicle collision, sitting position in ED, ambulatory at any time since injury, delayed onset of neck pain, or absence of midline C-spine tenderness)." If none of the five is present, the result is positive without testing rotation.

InputMeaning
simple_rear_end_mvcA simple rear-end motor vehicle collision
sitting_in_edSitting up in the emergency department
ambulatory_since_injuryHas walked at any time since the injury
delayed_neck_painNeck pain that started later rather than right away
midline_cspine_tendernessMidline cervical-spine tenderness. Note the direction: false (no tenderness) is the low-risk factor.

The record also lists what doesn't count as a simple rear-end collision: being pushed into oncoming traffic, being hit by a bus or large truck, a rollover, or being hit by a high-speed vehicle.

Question 3: can the person rotate the neck?

The third question is whether "the patient able to actively rotate neck 45 degrees to the left and right." It's consulted when there is no high-risk factor and at least one low-risk factor.

InputMeaning
able_to_rotate_45Able to actively turn the head 45 degrees to each side

What the calculator returns

Magent's calculator returns the rule's true/false result (in a field named xray_indicated) plus the three intermediate answers: whether a high-risk factor was present, whether a low-risk factor allowed range-of-motion assessment, and the rotation answer. It also echoes the age it used.

Worked examples

These use Magent's own expected values for the calculator. Unlisted findings are "no".

Example 1: age 40, delayed neck pain, can rotate

  1. Question 1: age 40 isn't high-risk; no dangerous mechanism or paresthesias. No high-risk factor.
  2. Question 2: delayed neck pain is a low-risk factor (midline tenderness is present, but one low-risk factor is enough).
  3. Question 3: can rotate 45 degrees each way.
  4. Result: negative.

Example 2: age 65

  1. Question 1: age 65 is a high-risk factor.
  2. Questions 2 and 3 aren't consulted.
  3. Result: positive.

Example 3: age 64, midline tenderness, no other low-risk factor

  1. Question 1: age 64 isn't high-risk.
  2. Question 2: midline tenderness is present and none of the other four low-risk factors is. No low-risk factor.
  3. Result: positive, without testing rotation.

Example 4: age 40, delayed neck pain, can't rotate

  1. Question 1: no high-risk factor.
  2. Question 2: delayed neck pain is a low-risk factor.
  3. Question 3: can't rotate 45 degrees each way.
  4. Result: positive.

Example 5: age 40, no midline tenderness, can rotate

  1. Question 1: no high-risk factor.
  2. Question 2: absence of midline tenderness is itself a low-risk factor.
  3. Question 3: can rotate.
  4. Result: negative.

Canadian C-spine reference values

These are Magent's expected values for the calculator. Age 40 with delayed neck pain and midline tenderness, able to rotate 45 degrees, is negative. Age 65 with nothing else is positive. Age 64 with midline tenderness and no low-risk factor is positive. Age 40 with delayed neck pain and midline tenderness turns positive when a dangerous mechanism or paresthesias is added, or when the person can't rotate 45 degrees. Age 40 with none of the findings, able to rotate, is negative.

History of the Canadian C-spine rule

The rule comes from Ian G. Stiell, George A. Wells, Katherine L. Vandemheen and colleagues, The Canadian C-spine rule for radiography in alert and stable trauma patients, JAMA, 2001 (volume 286, issue 15, pages 1841–1848).

The abstract describes a prospective cohort study in "Ten EDs in large Canadian community and university hospitals." It enrolled a "Convenience sample of 8924 adults (mean age, 37 years) who presented to the ED with blunt trauma to the head/neck, stable vital signs, and a Glasgow Coma Scale score of 15." Physicians evaluated each patient for 20 standardized clinical findings before radiography, and the rule was derived with the kappa coefficient, logistic regression and recursive partitioning.

When it's used

The 2001 study population was alert, stable adults after blunt trauma to the head or neck, with a Glasgow Coma Scale score of 15. Magent's record describes the same population and notes that the calculator doesn't take the Glasgow Coma Scale score; the caller assigns the findings.

Where it's used

The original study ran in ten emergency departments in large Canadian community and university hospitals.

Who uses it

In the 2001 study, emergency department physicians assessed the findings before radiography.

Limits of the calculation

  • It applies the three questions to the answers it's given. It doesn't examine the neck and doesn't diagnose an injury.
  • It's the Stiell 2001 Canadian C-spine rule. It isn't NEXUS and isn't a pediatric rule.
  • Dangerous mechanism and simple rear-end collision are the caller's call, using the definitions in Magent's record above.
  • The record describes the population as alert, stable adults with a Glasgow Coma Scale score of 15. The calculator doesn't check that.
  • Rotation is tested after the first two questions allow it. The calculator still takes the rotation answer every time, but uses it at that step alone.
  • This page doesn't say what to do with the result.

Clinical decisions belong to a qualified clinician who knows the patient.

  • NEXUS criteria is a different rule for the same question. It uses five findings (midline tenderness, focal deficit, alertness, intoxication, distracting injury), all of which must be absent, and has no age input or rotation test.

Glossary

  • C-spine: the cervical spine, the seven bones of the neck.
  • Paresthesias: tingling, prickling or pins and needles.
  • Axial load: force driven down through the top of the head.
  • Range of motion: how far the neck can move; here, turning the head side to side.
  • Glasgow Coma Scale (GCS): a 3–15 score of eye, verbal and motor response; 15 is fully responsive.

Common mistakes

  • Treating it as a checklist. The three questions run in order. A high-risk factor ends the process before rotation is considered.
  • Reading midline tenderness backwards. The low-risk factor is the absence of midline tenderness.
  • Counting any rear-end collision as "simple." Magent's record lists exclusions that include a rollover or being hit by a bus, large truck or high-speed vehicle.
  • Using a different age cutoff. The high-risk age is 65 or older.
  • Mixing it up with NEXUS. NEXUS uses different findings and no rotation step.

Source

Stiell IG, Wells GA, Vandemheen KL, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001;286(15):1841-1848. DOI: 10.1001/jama.286.15.1841

Frequently asked questions

What is the Canadian C-spine rule?

A 2001 decision rule for alert, stable adults after blunt trauma to the head or neck. It asks three questions in order: any high-risk factor, any low-risk factor allowing range-of-motion assessment, and whether the person can rotate the neck 45 degrees to each side.

What are the high-risk factors?

Age 65 or older, a dangerous mechanism, or paresthesias in the arms or legs.

What are the low-risk factors?

A simple rear-end motor vehicle collision, sitting in the emergency department, walking at any time since the injury, delayed onset of neck pain, or absence of midline cervical-spine tenderness.

What should happen after the rule is applied?

This page doesn't give disposition advice. What to do next depends on the clinical context.

Is the Canadian C-spine rule the same as NEXUS?

No. They're separate rules with different findings.

Who developed the Canadian C-spine rule?

Ian Stiell and colleagues, in a 2001 paper in JAMA.