NEXUS Criteria and the Canadian C-Spine Rule: Spinal Motion Restriction

NEXUS and the Canadian C-Spine Rule are clinical decision rules for neck injury. Both were built in emergency departments to answer one question: which trauma patients can safely skip imaging of the cervical spine. Many EMS systems have adapted the same reasoning to a different question, which patients need spinal motion restriction (SMR) in the field. Knowing where the rules came from helps you apply them the way your protocol intends.

The five NEXUS criteria

NEXUS (the National Emergency X-Radiography Utilization Study, published in 2000) found that a blunt trauma patient who meets all five of these criteria is at very low risk of a significant cervical spine injury:

1. No tenderness in the posterior midline of the cervical spine.
2. No evidence of intoxication.
3. A normal level of alertness.
4. No focal neurologic deficit.
5. No painful distracting injury.

If any one of the five is not met, the patient does not clear by NEXUS. The rule is easy to remember and needs no special equipment, which is why so many field protocols use a version of it.

Score the level of consciousness, one of the things both rules depend on

The Canadian C-Spine Rule

The Canadian C-Spine Rule (published in 2001) applies to alert, stable adult trauma patients. It asks three questions in order.

1. Is there any high-risk factor?

• Age 65 or older.
• A dangerous mechanism: a fall from 3 feet or 5 stairs or more, an axial load to the head such as a diving injury, a high-speed motor vehicle collision, a rollover or ejection, a collision involving a motorized recreational vehicle, or a bicycle collision.
• Numbness or tingling (paresthesias) in the extremities.

If yes, the patient needs imaging and does not clear by the rule.

2. Is there any low-risk factor that allows a safe range-of-motion check?

• A simple rear-end motor vehicle collision. This excludes being pushed into oncoming traffic, being hit by a bus or large truck, a rollover, and being hit by a high-speed vehicle.
• Sitting up in the emergency department.
• Walking at any time since the injury.
• Neck pain that started later rather than immediately.
• No midline cervical spine tenderness.

If there is no low-risk factor, the patient needs imaging. If there is one, go to the third question.

3. Can the patient actively rotate the neck 45 degrees to the left and to the right?

If they can, the rule says no imaging is needed. If they cannot, they need imaging. The patient turns their own head; nobody turns it for them.

The rule does not apply to patients with a GCS under 15, unstable vital signs, age under 16, acute paralysis, known vertebral disease or prior cervical spine surgery, or penetrating trauma, among other exclusions in the original study.

NEXUS and the Canadian rule side by side

Spinal motion restriction in the field

In 2018 three national bodies published a joint position statement on spinal motion restriction: ACS-COT (the trauma committee of the national college of surgeons), ACEP (the national college of emergency physicians), and the National Association of EMS Physicians (NAEMSP). It replaced the idea of immobilizing every trauma patient with a narrower set of indications and a different method.

Indications for SMR after blunt trauma

• An acutely altered level of consciousness, including intoxication.
• Midline neck or back pain or tenderness.
• Focal neurologic signs or symptoms such as numbness or weakness.
• An anatomic deformity of the spine.
• Distracting circumstances or injuries, or anything else that keeps the patient from giving a reliable exam.

What the statement says about method

• The goal is to limit movement of the spine, not to immobilize the patient completely. A cervical collar with the patient kept aligned on the stretcher is enough for most patients.
• A long backboard is a tool for extrication and moving a patient, not a treatment. Get the patient off it as soon as it is practical.
• Penetrating trauma to the head, neck or torso without evidence of spinal injury (such as a neurologic deficit) does not need SMR. Applying it can delay transport and hide injuries.
• In children, age alone is not an indication. The same criteria apply, and the child's ability to give a reliable exam matters as much as it does in an adult.

Common mistakes

• Clearing a patient who cannot give a reliable exam because they say their neck feels fine.
• Using the Canadian rule on a patient it excludes, such as a child or a patient with a GCS under 15.
• Applying SMR to a penetrating injury without evidence of spinal injury and delaying transport to do it.
• Leaving a patient on a long board for the whole transport.
• Turning the patient's head for them during the rotation test.

The short version

• NEXUS: no midline tenderness, no intoxication, normal alertness, no focal deficit, no distracting injury.
• Canadian C-Spine Rule: high-risk factor means image; no low-risk factor means image; otherwise test active rotation of 45 degrees each way.
• Both are ED imaging rules that field protocols adapt.
• Every criterion assumes a patient who can give a reliable exam.
• SMR limits motion. A collar and a stretcher is the method for most; a backboard is for extrication.
• Penetrating trauma to the head, neck or torso without evidence of spinal injury does not get SMR.
• Your spinal protocol governs.