The relative effect of upper cervical spine manipulation, placebo and a control, on neck muscle activity, pain and disability in participants with cervicogenic headache

Abstract

Objectives: Cervical spinal manipulation (CSM) has been shown to be effective in treating cervicogenic headache (CGH) by reducing pain and disability. There is a paucity of research investigating whether changes in muscle activity account for the changes in patient reported outcomes in patients with CGH following CSM. The aim of this study was to determine the effect of upper CSM compared to a placebo and a control intervention in terms of subjective (pain and disability rating) and objective measures (muscle activity and force output of the trapezius, posterior cervical and sternocleidomastoid muscles) in the treatment of CGH. Methods: A randomized, controlled, pre-test, post-test, experimental design allowed for 45 participants, aged 18-50, with CGH to be allocated to a CSM, placebo or control group. Pain and disability were measured before and telephonically 48 hours after the intervention. Muscle activity and force output of the trapezius, posterior cervical and sternocleidomastoid (SCM) muscles were measured before and immediately after the intervention. IBM SPSS was used to analyse the data with significance set at p=0.05. The subjective and objective measures were not normally distributed and this resulted in nonparametric statistical tests being utilised to analyse the data. Wilcoxon Signed Rank Tests were used to determine significance within groups and Independent-samples KruskalWallis Tests and Pairwise multiple comparison tests were used to determine significance between groups. Results: No significant differences were found between the three groups for age (p=0.460) and gender (p=0.566), with a marginally significant finding for race (p=0.046). Subjective measure assessment found only a significant decrease in pain (p=0.001) and disability (p=0.001) from pre- post-test within the CSM group. Intergroup analysis found that the CSM group experienced the greatest reduction in pain (p=0.001) and disability (p=0.001) when compared to the placebo and control groups. Clinically, only pain in the CSM group decreased significantly. Objective findings showed significant intragroup increases in muscle activity, found bilaterally in the SCM (p=0.017 SCMR) (p=0.012 SCML) and trapezius muscles (p=0.041 TrapR) (p=0.041 TrapL) in the CSM group and only in the trapezius muscle (p=0.031 TrapR) (p=0.027 TrapL) bilaterally in the placebo group. Force output only increased in the trapezius muscle on the left (p=0.027) in the placebo group and bilaterally in the control group (p=0.031 TrapR) (p=0.041 TrapL) There were no significant intergroup differences between the groups for muscle activity and force output in the trapezius, posterior cervicals and SCM