Editor’s note, 11/30/21: Please see comment from Dr. Stephen Smith about Canadian C-spine Rule below. Post has been slightly modified from original based on this feedback. ~Clay Smith
Written by Nickolas Srica
Over half of the patients who had NOT undergone any head or neck trauma were found to have midline cervical spine tenderness to palpation, likely contributing to the high sensitivity but low specificity of clinical decision rules such as the NEXUS criteria.
Why does this matter?
If missed, traumatic cervical spine injuries can potentially lead to catastrophic outcomes. For this reason, clinicians often over-image these patients, increasing cost and radiation exposure. We rely on clinical decision rules (CDR), such as the Canadian C-Spine Rule (CCR) and the National Emergency X-Radiography Utilization Study (NEXUS) criteria, to decrease diagnostic testing, both of which use the presence of midline c-spine tenderness as one of the criteria in favor of obtaining further imaging. The question is, what is the prevalence of midline c-spine tenderness in patients who did not undergo any head or neck trauma, and could this be playing a role in the high sensitivity and low specificity of these CDRs (see comment on CCR from Dr. Stephen Smith below)?
My neck, my back, hurts even when my car ain’t crashed…
This was a prospective study of 478 patients enrolled in an urban Canadian ED and a university sports medicine clinic from August 2018 through March 2020. They divided the c-spine of each participant into an upper, middle, and lower segment, and then two separate examiners palpated for tenderness at least 5 minutes apart while being blinded to the findings of the other examiner. They also palpated the scaphoid of each participant to determine who might be more sensitive to bony palpation. Other risk factors for tenderness that were also noted were gender, age, BMI, c-spine length, and neck circumference. There were several exclusion criteria, including any suspected trauma to the head or neck area, previous significant injury to these areas, any headache or neck pain on presentation or chronically, known neck osteoarthritis, recent alcohol or analgesics, and distracting injuries, to name a few.
Of the 478 patients enrolled, 254 were women, and more than half (59.8%) of all participants had midline c-spine tenderness with both examiners, and 63.8% had tenderness with at least one examiner. Women and those with scaphoid tenderness were significantly more likely to have c-spine tenderness at baseline, while increasing BMI was associated with lower odds of c-spine tenderness. The middle and upper thirds of the c-spine were the areas that were more likely to have tenderness, while lower third c-spine tenderness was much rarer. Given these findings, it’s possible that a significant portion of the population may meet criteria for imaging of the c-spine by some CDRs even before ever sustaining any trauma.
Limitations: This study population was from one tertiary care ED and one sports medicine clinic in the same city, possibly not reflecting the general population. Only two examiners participated in this study, possibly not reflecting how other clinicians may palpate the c-spine. More investigation will be needed to see how some of these factors could potentially be used to improve the specificity of some of our commonly used CDRs.
Prevalence of Midline Cervical Spine Tenderness in the Non-Trauma Population. Emergency Medicine Journal. 2021. doi: 10.1136/emermed-2021-211288