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Alan Brewster, BS, DC & Claudia Seay, BS, DC
Annals of Vertebral Subluxation Research ~ Volume 2022 ~ February 14 ~ Pages 60-64
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Abstract
Background: The cervical syndrome (CS) check has been used extensively in the practice of chiropractic, and there exist many robust theories concerning its neurological mechanism – from Thompson’s “innervational overload of the extensor muscles”, to Grostic’s “Dentate Ligament / Cord Distortion Hypothesis”. However, research on the effect of the cervical syndrome check on paraspinal muscles and the relationship to vertebral subluxation throughout the spine appears incomplete.
Methods: In this pilot study, sEMG was used to evaluate paraspinal muscle recruitment bilaterally at L1 during both actual and sham cervical syndrome checks. The investigator acquiring and analyzing the sEMG was blinded as to whether the subject performed an actual or sham CS maneuver, and whether a leg length inequality (LLI) change was elicited. For the purposes of this study, the only criterion was whether a leg length change occurred, without regard for the CS category of that change if one occurred.
Results: In the presence of an asymmetrical LLI change (an asymmetrical spinal/pelvic response), the proportional change of paraspinal recruitment was also asymmetrical. In the presence of a symmetrical LLI change (indicating a symmetrical spinal/pelvic response), the symmetry of paraspinal recruitment was high. No correlation of LLI to amplitude of paraspinal potentials was found.
Conclusion: There is a direct correlation between symmetry of prone LLI changes during bilateral cervical rotation and symmetry of bilateral changes in paraspinal muscle activity at L1. However, the sEMG potential during neutral head position is often asymmetrical, and amplitude of sEMG potentials is not correlated to laterality of LLI change. Because muscle palpation has often exhibited poor inter-examiner reliability, sEMG may provide a greater level of reliability for precise analysis of cervical syndrome and ultimately vertebral subluxation.
Key words: sEMG, surface electromyography, cervical syndrome, chiropractic
