Canadian C-Spine Rule

The question it answers. In an alert, stable adult after blunt trauma, does this neck need imaging at all? The rule decides who gets imaged; the pages around it decide what happens next. A patient who fails it goes on to imaging and, if positive, into cervical spine fracture and its subsets - subaxial injuries and, at the top of the column, atlanto-occipital dislocation, the injury this rule exists to avoid missing. The neurological consequence is spinal cord injury, and the rule itself sits inside the wider ATLS primary survey.

Excluded rather than cleared. Some patients sit outside the rule altogether and are imaged whatever the bedside findings: the patient with ankylosing spondylitis, with DISH, or with a previous cervical fusion - any fused spine. A trivial mechanism in a rigid column produces an unstable fracture, and the rule was never validated on them.

Step two. With no high-risk factor present, at least one low-risk factor is what makes active range-of-motion assessment safe to attempt. If none of the five is present, the patient is imaged without testing rotation.

Algorithm

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Step three: active rotation. When a low-risk factor allows it, ask for active rotation of 45 degrees to each side. Full and painless rotation in both directions clears the cervical spine clinically, and no film is required by the rule.

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How it compares with NEXUS. The Canadian C-Spine Rule is more specific than the NEXUS criteria and reduces unnecessary imaging to a greater degree, with at least equivalent - and, in the head-to-head trial, higher - sensitivity.

Where the rule is weakest. It has been validated across multiple centres and trauma systems but performs best when applied by trained emergency physicians or trauma team members. Inter-observer reliability for the low-risk factors and the range-of-motion assessment is good but not perfect, which is why each criterion and the rotation result are documented explicitly.

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