The effect of cervical spine manipulation on laterality judgement ability in participants with persistent neck pain
Authors:   , Bradford Benjamin 
Published: November 2022

BACKGROUND Neck pain is among the top twenty most burdensome chronic health conditions worldwide. The severity of neck pain among patients varies, but it has been found that about 50% of episodes tend to become chronic. Previous research has used the accuracy with which the laterality of body parts can be identified as a proxy for cortical body schema accuracy and integrity. Treatments aimed at addressing such cortical maladaptations to pain have been effective in reducing pain and dysfunction in a number of conditions. More specifically, spinal manipulation (SM) has been shown to improve the laterality judgement reaction time (LJRT) of participants regarding alphabetical characters. However, the effect of SM on laterality judgment accuracy (LJA) regarding body parts has not been determined. Moreover, it has been shown that the neurological mechanisms by which the brain determines the laterality of letters and objects (allocentric mechanisms) are distinct from those involved in laterality judgements of body parts (egocentric mechanisms). This study investigated the effects of cervical spinal manipulation on LJA using Neck and Hand images as well as the ‘R’ alphabetical character to determine whether SM was able to address distortions in cortical body schema mapping that may have contribute to persistent neck pain. AIM The overarching aim of the study was to determine the immediate effect of cervical spinal manipulation on laterality judgement reaction time (LJRT) and laterality judgement accuracy (LJA) in participants with persistent neck pain. METHODOLOGY The study adopted a quantitative paradigm and was a pre-test, post-test experimental trial. People between the ages of 18 and 55 with a current history of non-traumatic neck pain for 4 weeks or more were invited to participate in the study. The selected participants were randomly allocated to either the intervention or the control group. Further screening was conducted by means of a telephonic interview, the elicitation of a medical history, a full physical examination, and a cervical regional examination to ensure that there were no contraindications to their participation in the study. Applicants were excluded if they had received any treatment for their neck pain in the foregoing three months. A total of 58 participants was formally included and randomly allocated to either the intervention or control group. Each participant was then submitted to a pre-intervention/control test for laterality judgment ability in terms of the letter ‘R’ and Hand and Neck images using the commercially available Recognize application. Following the application of the respective interventions (i.e., spinal manipulation and a set up for spinal manipulation without thrust), post-test measurements were taken as before. Each participant also completed a Central Sensitization Inventory (CSI) at the time of participation. The paired t-tests was used to compare paired means within groups from pre- to posttreatment. Repeated ANOVA measures were used to compare the changes over time between the two treatment groups, while profile plots were used to assess the direction and trend of the effect of the intervention. Correlations between changes in the scores of the alphabetical character ‘R’, Hand, and Neck were assessed using Pearson’s correlation analysis. The same was used to assess the correlation between changes in Laterality judgement performance and CSI scores. These correlations were done for the entire sample regardless of treatment group. Ethical approval (IREC 013/20) for the study was obtained from the relevant institution’s research ethics committee prior to commencement (Appendix A). FINDINGS Both groups showed significant improvements over time between the pre- and postintervention tests, but improvements in the intervention group were statistically indistinguishable from those of the control group. Additionally, there was no correlation between measures of allocentric and egocentric laterality judgement ability. No relationship was found between CSI scores and laterality judgement performance or improvement over time.