| Abstract/Notes |
Introduction: Previous investigations have demonstrated highly consistent and highly significant effects of unilateral spinal adjustments in normalizing left-right passive motion asymmetry in asymptomatic subjects. However, examination of other parameters (e.g. end-range discomfort), which might be associated with restrictions of passive end-range capability, were not included in those studies. Therefore, it was decided that an assessment of the degree of discomfort at end-range experienced by asymptomatic subjects with passive motion asymmetry was in order. Methods: This study was reviewed and approved by the Institutional Review Board of the Palmer Center For Chiropractic Research. Volunteer chiropractic students ranging from 22-43 years of age were selected as subjects and a cervical range of motion (CROM) pendulum goniometer (Performance Attainment Associates, St. Paul, MN) was used for passive end-range assessments. The CROM has been previously validated as an accurate measuring device for analyzing cervical range of motion. Starting from the neutral position, five left and five right alternating passive lateral-flexion end-range measures were obtained from each subject. As in earlier studies, subjects were instructed to relax and close their eyes prior to each measure. In order to control for operator bias, the goniometric assessor stood behind the seated subject, and all measurements were read and recorded by another experimenter who stood in front of the subject. Seated subjects were instructed to rest their forearms on a table in front of them during the alternating measures, so as to keep “shoulder roll” to a minimum. Additionally, immediately following the first and again following the last of the five alternating measures, subjects were instructed to indicate the degree of discomfort they experienced at end-range. A 10-point numeric discomfort scale was employed for end-range discomfort determinations, with a score of 10 defined as “ouch - stop, that hurts”. Results: As in earlier studies, mean left versus mean right goniometric differences of 5° or more were always significant at p <0.05 levels or better, whereas mean left versus mean right differences of less than 5° often did not meet 0.05 levels of significance. On the other hand, mean left versus mean right differences greater than 10° were always significant at p<0.001 levels of significance or better. Furthermore, there was a strong correlation between the magnitude of end-range asymmetry (i.e., left-right difference) and the severity of discomfort experienced when subjects were taken to their most restricted side of end-range. For passive end-range differences of less than 10°, discomfort scores all fell between zero and five on the discomfort scale (mean = 1.8 ± 1.1), whereas for passive end-range restrictions of 10° or greater, end-range discomfort scores all fell between four and nine (mean = 6.4 ± 1.6). Interestingly, in subjects exhibiting mild restrictions of less than 10°, discomfort scores were higher when the subject was taken to their most restricted side, but the discomfort was always experienced on the contralateral side of their neck. On the other hand, in subjects exhibiting more severe passive end-range restrictions of greater than 10°, not only were end-range discomfort scores much higher, but were experienced on the side of the neck ipsilateral to the side of most restricted end-range. Discussion: These results suggest that mild end-range restrictions may merely be caused by a “tugging” action against relatively hypertonic contralateral muscles, most likely superficial ones. On the other hand, more severe end-range restrictions may primarily involve the deep intra-vertebral muscles ipsilateral to the side of most restricted end-range, or may involve discomfort emanating from articular structures consequent to aberrant joint biomechanics. This abstract is reproduced with the permission of the publisher. |
