How to Apply the Canadian C-Spine Rule
The Canadian C-Spine Rule is a three-step clinical decision algorithm that determines whether cervical spine imaging is needed in alert and stable trauma patients by first assessing high-risk factors, then low-risk factors, and finally testing active neck rotation. 1
Patient Eligibility Criteria
Before applying the rule, confirm the patient meets ALL of the following prerequisites 1:
- Alert with GCS = 15 (fully oriented)
- Stable vital signs
- No intoxication (alcohol or drugs)
- Age ≥16 years (for pediatric patients, use PECARN criteria instead) 1
Step 1: Assess High-Risk Factors (Mandatory Imaging)
If ANY of the following are present, proceed directly to cervical spine imaging 1:
- Age ≥65 years
- Dangerous mechanism of injury:
- Fall from elevation ≥3 feet or 5 stairs
- Axial load to head (diving injury)
- High-speed motor vehicle crash (>100 km/hr)
- Rollover or ejection from vehicle
- Motorized recreational vehicle crash
- Bicycle collision
- Paresthesias in extremities (numbness, tingling in arms or legs)
Step 2: Assess Low-Risk Factors (Safe for Physical Examination)
If no high-risk factors are present, check for ANY of these low-risk factors that allow safe assessment of neck range of motion 1:
- Simple rear-end motor vehicle collision (excludes: pushed into oncoming traffic, hit by bus/large truck, rollover, high-speed)
- Sitting position in emergency department
- Ambulatory at any time since injury
- Delayed onset of neck pain (not immediate)
- Absence of midline cervical tenderness
If NONE of these low-risk factors are present, proceed to imaging. 1
Step 3: Active Neck Rotation Test
If at least one low-risk factor is present, ask the patient to actively rotate their head 1:
- Patient must rotate head 45 degrees to the left AND right (past midline in both directions)
- If able: cervical spine is clinically cleared—no imaging needed
- If unable or unwilling: proceed to imaging
Performance Characteristics
The Canadian C-Spine Rule demonstrates 1, 2:
- Sensitivity: 99.6-100% for clinically important cervical spine injuries
- Specificity: 37.7-43.9% (intentionally low to maximize safety)
- Can reduce unnecessary imaging by approximately 40% 2, 3
Critical Pitfalls to Avoid
Do not apply the Canadian C-Spine Rule if 1:
- GCS <15 (altered mental status)
- Intoxication present (impairs reliable examination)
- Distracting painful injuries (may mask neck pain)
- Neurological deficits present (requires immediate imaging, consider MRI) 1, 4
- Obtunded or unconscious patients (requires CT imaging regardless) 1
Special consideration for elderly patients (≥65 years): These patients automatically qualify for imaging under the high-risk criteria, as clinical examination has reduced sensitivity in this population. 1, 5
Comparison with NEXUS Criteria
While both the Canadian C-Spine Rule and NEXUS criteria have similar sensitivity (99.6%), the Canadian C-Spine Rule has higher specificity and is more effective at reducing unnecessary imaging 1. The Canadian C-Spine Rule uses a more complex algorithm but provides clearer guidance for clinical decision-making, particularly through the active rotation test component. 1
Implementation by Non-Physicians
The Canadian C-Spine Rule has been successfully validated for use by paramedics (sensitivity 100%, kappa 0.93) and emergency department triage nurses (sensitivity 90.2% after training, kappa 0.78), allowing earlier clinical clearance and reduced immobilization time. 2, 3