The Comparative Effects of Spinal and Peripheral Thrust Manipulation and Exercise on Pain Sensitivity and the Relation to Clinical Outcome: A Mechanistic Trial Using a Shoulder Pain Model

Abstract

STUDY DESIGN Single-blind randomized trial. OBJECTIVES To compare the effects of cervical and shoulder thrust manipulation (TM) and exercise on pain sensitivity, and to explore associations with clinical outcomes in patients with shoulder pain. BACKGROUND Experimental studies indicate that spinal TM has an influence on central pain processes, supporting its application for treatment of extremity conditions. Direct comparison of spinal and peripheral TM on pain sensitivity has not been widely examined. METHODS Seventy-eight participants with shoulder pain (36 female; mean ± SD age, 39.0 ± 14.5 years) were randomized to receive 3 treatments of cervical TM (n = 26), shoulder TM (n = 27), or shoulder exercise (n = 25) over 2 weeks. Twenty-five healthy participants (13 female; mean ± SD age, 35.2 ± 11.1 years) were assessed to compare pain sensitivity with that in clinical participants at baseline. Primary outcomes were changes in local (eg, shoulder) and remote (eg, tibialis anterior) pressure pain threshold and heat pain threshold occurring over 2 weeks. Secondary outcomes were shoulder pain intensity and patient-rated function at 4, 8, and 12 weeks. Analysis-of-variance models and partial-correlation analyses were conducted to examine comparative effects and the relationship between measures. RESULTS At baseline, clinical participants demonstrated lower local (mean difference, −1.63 kg; 95% confidence interval [CI]: −2.40, −0.86) and remote pressure pain threshold (mean difference, −1.96 kg; 95% CI: −3.09, −0.82) and heat pain threshold (mean difference, −1.15°C; 95% CI: −2.06, −0.24) compared to controls, suggesting enhanced pain sensitivity. Following intervention, there were no between-group differences in pain sensitivity or clinical outcome (P>.05). However, improvements were noted, regardless of intervention, for pressure pain threshold (range of mean differences, 0.22–0.32 kg; 95% CI: 0.03, 0.43), heat pain threshold (range of mean differences, 0.30–0.58; 95% CI: 0.06, 0.96), pain intensity (range of mean differences, −1.79 to −1.45; 95% CI: −2.34, −0.94), and function (range of mean differences, 3.15–3.82; 95% CI: 0.69, 6.20) at all time points. We did not find an association between pain sensitivity changes and clinical outcome (P>.05). CONCLUSION Clinical participants showed enhanced pain sensitivity, but did not respond differently to cervical or peripheral TM. In fact, in this sample, cervical TM, shoulder TM, and shoulder exercise had similar pain sensitivity and clinical effects. The lack of association between pain sensitivity and clinical pain and function outcomes suggests different (eg, nonspecific) pain pathways for clinical benefit following TM or exercise.

Effectiveness of manual therapy versus surgery in pain processing due to carpal tunnel syndrome: A randomized clinical trial

“…Finally, we did not observe any association between changes in clinical pain intensity and changes in pressure or thermal pain hyperalgesia. Current results agree with a previous study conducted on shoulder pain where no association between pain sensitivity changes and clinical outcomes were identified (Coronado et al., ). This may be related to the fact that clinical outcomes such as pain and function do not exhibit an association with neuro‐physiological outcomes such as PPTs (Hübscher et al., ).…”

Manipulation-induced hypoalgesia in musculoskeletal pain populations: a systematic critical review and meta-analysis

“…T4 supine HVLA SMT2. T4 toggle-recoil HVLA SMT(2nd if no cavitation) Nil PPT @ C4 SP, T4 SP, & upper trapeziusLocal & remoteImmediate20 minCoronado 2015, USA [33]3 arm RCT78 (26/27/25)39 (NR)42/36General shoulder painGeneral population & primary careMid-cervical HVLA SMT (NR if pre-specified, 2nd if no cavitation)1. Shoulder manipulation2.…”

“…There was a mixture of spinal pain and pain in other areas; seven non-specific neck pain [21, 26–31], four non-specific low back pain [22, 23, 25, 32], one temporomandibular disorder with non-specific neck pain [24], and three extremity pain [33–35]. Nine studies where performed on chronic pain populations [21, 24–29, 31, 32], and six on study samples with mixed or unknown chronicity [22, 23, 30, 33–35].…”

“…Thirteen studies utilised PPT as an outcome measure [21, 24–35]. Temporal summation was measured in two studies [22, 33], but pre-post intervention scores were not analysed in one of these [33]. Heat pain detection threshold was measured in two studies [33, 34].…”

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

“…First, HPT was not assessed at the primary exercised muscle where EIH would have been greatest. Second, in order to equate the method of measuring heat pain with that of pressure pain, we stimulated a much smaller surface area and more rapidly increased heat than previous studies (Kodesh and Weissman-Fogel, 2014; Coronado et al, 2015). Third, EIH is larger and more consistent when mechanical rather than thermal stimuli are used to evoke pain (Koltyn, 2000; Hoffman et al, 2004; Ruble et al, 2005; Naugle et al, 2012; Vaegter et al, 2016), but exactly why this occurs is not known.…”