A randomised, independent groups study investigating the sympathetic nervous system responses to two manual therapy treatments in patients with LBP

[Manual spinal therapy techniques to stimulate the autonomic nervous system: a scoping review]

BACKGROUND

Physical interventions or manual therapeutic techniques (MTTe) such as mobilisation, manipulation or soft tissue techniques not only have an influence on the target tissue with improvement of metabolism or reduction of hypertonic muscles. They are also used for balance regulation in central nervous changes of the autonomic nervous system (ANS). To date, there is a lack of empirical evidence on impact mechanisms and target locations of MTTe on the ANS. This scoping review aims to provide an overview of the evidence on the application of MTTe at diverse levels of the spine with a view to the ANS.

METHOD

A systematic literature search was conducted on CENTRAL, Google Scholar, Osteopathic Research Web, PEDro and PubMed. The scope and content of the literature were documented. The results of the included and referenced studies were summarised in a narrative approach with the focus being on the most significant clinical aspects.

RESULTS

MTTe was described as manipulations, mobilisations, myofascial techniques and cervical traction. In 27 out of 35 studies, therapeutic treatments were carried out on healthy volunteers. Ten studies analysed immediate effects in patients, while two studies were designed as longitudinal studies in patients with hypertension. Over a period of four to eight weeks, the frequency of intervention was between one and three MTTe sessions a week.

CONCLUSION

The study results proved to be heterogeneous. For this reason, it is not possible to draw definitive, explicit and generally valid statements regarding the type and intensity as well as the segmental level at which MTTe should be applied in order to trigger specific positive ANS response mechanisms. Consequently, longitudinal studies with follow-up are recommended for future studies. In addition, comprehensive effects of MTTe should be evaluated in groups of patients with different characteristics.

Does transcutaneous electrical nerve stimulation affect pain, neuropathic pain, and sympathetic skin responses in the treatment of chronic low back pain? A randomized, placebo-controlled study

Background

The purpose of this study was to assess the effectiveness of transcutaneous electrical nerve stimulation (TENS) in chronic low back pain and neuropathic pain.

Methods

Seventy-four patients aged 18-65 with chronic low back pain were included in the study. Baseline measurements were performed, and patients were randomized into three groups. The first group received burst TENS (bTENS), the second group conventional TENS (cTENS), and the third group placebo TENS (pTENS), all over 15 sessions. Patients' visual analogue scale (VAS) scores were evaluated before treatment (preT), immediately after treatment (postT), and in the third month after treatment (postT3). Douleur Neuropathique 4 Questions (DN4), the Modified Oswestry Low Back Pain Disability Questionnaire (MOS), the Beck Depression Inventory (BDI), and sympathetic skin response (SSR) values were also evaluated preT and postT3.

Results

A statistically significant improvement was observed in mean VAS scores postT compared to preT in all three groups. Intergroup comparison revealed a significant difference between preT and postT values, that difference being assessed in favor of bTENS at multiple comparison analysis. Although significant improvement was determined in neuropathic pain DN4 scores measured at postT3 compared to preT in all groups, there was no significant difference between the groups. No statistically significant difference was also observed between the groups in terms of MOS, BDI, or SSR values at postT3 (P > 0.05).

Conclusions

bTENS therapy in patients with low back pain is an effective and safe method that can be employed in short-term pain control.

Short term relief of multisite chronicpain with Bowen Therapy: A double-blind, randomized controlled trial

INTRODUCTION

Bowen Therapy, a form of soft tissue manipulation, is commonly used to treat musculoskeletal conditions; yet, there is little evidence for its efficacy. The goal of the study was to investigate the impact of Bowen Therapy on pain and function in people with chronic pain in multiple locations. Additionally, we examined the mechanisms of effect through monitoring the nociceptive and autonomic nervous systems.

METHOD

The study was a double-blind, randomized controlled trial involving 31 people with chronic pain. Participants were randomized into real and sham therapy groups. Each group received 6 sessions of therapy over 8 weeks. The primary outcome measures of pain and function were assessed using standard questionnaires. Quantitative sensory testing was used to assess the nociceptive system, while recordings of heart rate variability and skin conductance were used to assess the autonomic nervous system. Outcome measures were assessed at baseline and at 1- and 6-weeks following completion of the intervention.

RESULTS

The real therapy group had a significantly lower pain score 1-week following the intervention compared to the sham group. There were no differences between groups at the final follow-up or in the function measures. There was no significant change in the nociceptive measures but there was evidence of increased activation of the sympathetic nervous system.

DISCUSSION

Bowen Therapy gave rise to a short-term reduction in pain that was not evident in a sham therapy group. The mechanisms of action of Bowen Therapy remain uncertain but may involve sympathoexcitation.

Toward a Theory of the Mechanism of High-Velocity, Low-Amplitude Technique: A Literature Review

This review seeks to integrate the current literature to create a more unified and inclusive theory regarding the therapeutic mechanism of high-velocity, low-amplitude (HVLA) technique. The authors review the literature currently available regarding the physiologic effects of HVLA. The progression from an articulatory model to a neuromuscular one is discussed, and the body of work demonstrating that HVLA has a centralized mechanism of action, rather than just a local one, is described.

The effect of manual therapy to the thoracic spine on pain-free grip and sympathetic activity in patients with lateral epicondylalgia humeri. A randomized, sample sized planned, placebo-controlled, patient-blinded monocentric trial

Background

The treatment of first choice for lateral epicondylalgia humeri is conservative therapy. Recent findings indicate that spinal manual therapy is effective in the treatment of lateral epicondylalgia. We hypothesized that thoracic spinal mobilization in patients with epicondylalgia would have a positive short–term effect on pain and sympathetic activity.

Methods

Thirty patients (all analyzed) with clinically diagnosed (physical examination) lateral epicondylalgia were enrolled in this randomized, sample size planned, placebo-controlled, patient-blinded, monocentric trial. Pain-free grip, skin conductance and peripheral skin temperature were measured before and after the intervention. The treatment group (15 patients) received a one-time 2-min T5 costovertebral mobilization (2 Hz), and the placebo group (15 patients) received a 2-min one-time sham ultrasound therapy.

Results

Mobilization at the thoracic spine resulted in significantly increased strength of pain-free grip + 4.6 kg ± 6.10 (p = 0.008) and skin conductance + 0.76 μS ± 0.73 (p = 0.000004) as well as a decrease in peripheral skin temperature by − 0.80 °C ± 0.35 (p < 0.0000001) within the treatment group.

Conclusion

A thoracic costovertebral T5 mobilization at a frequency of 2 Hz shows an immediate positive effect on pain-free grip and sympathetic activity in patients with lateral epicondylalgia.

Clinical trial registration

German clinical trial register DRKS00013964, retrospectively registered on 2.2.2018.

Effects of joint mobilisation on clinical manifestations of sympathetic nervous system activity: a systematic review and meta-analysis

BACKGROUND

A potential mechanism of action of manual therapy is the activation of a sympathetic-excitatory response.

OBJECTIVE

To evaluate the effects of joint mobilisation on changes in clinical manifestations of sympathetic nervous system activity.

DATA SOURCES

MEDLINE, EMBASE, AMED, CINAHL, EBSCO, PubMed, PEDro, Cochrane Collaboration Trials Register, Cochrane Database of Systematic Reviews and SCOPUS databases.

STUDY SELECTION

Randomised controlled trials that compared a mobilisation technique applied to the spine or the extremities with a control or placebo.

DATA EXTRACTION AND DATA SYNTHESIS

Human studies collecting data on skin conductance or skin temperature were used. Data were extracted by two reviewers. Risk of bias was assessed using the Cochrane guidelines, and quality of evidence was assessed using the GRADE approach. Standardised mean differences (SMD) and random effects were calculated.

RESULTS

Eighteen studies were included in the review and 17 were included in the meta-analysis. The meta-analysis found a significant increase in skin conductance [SMD 1.21, 95% confidence interval (CI) 0.88 to 1.53, n=269] and a decrease in temperature (SMD 0.92, 95% CI -1.47 to -0.37, n=128) after mobilisation compared with the control group. An increase in skin conductance (SMD 0.73, 95% CI 0.51 to 0.96, n=293) and a decrease in temperature (SMD -0.50, 95% CI -0.82 to -0.18, n=134) were seen after mobilisation compared with placebo. The risk of bias was generally low, but the heterogenicity of the results downgraded the level of evidence.

LIMITATIONS

Most trials (14/18) were conducted on asymptomatic healthy subjects.

CONCLUSION

There is moderate evidence suggesting a sympatho-excitatory effect of joint mobilisation. Systematic Review Registration Number PROSPERO CRD42018089991.

The effect of a single spinal manipulation on cardiovascular autonomic activity and the relationship to pressure pain threshold: a randomized, cross-over, sham-controlled trial

Background

The autonomic nervous system interacts with the pain system. Knowledge on the effects of high velocity low amplitude spinal manipulations (SM) on autonomic activity and experimentally induced pain is limited. In particular, the effects of SM on autonomic activity and pain beyond the immediate post intervention period as well as the relationship between these two outcomes are understudied. Thus, new research is needed to provide further insight on this issue.

Objectives

The aim was to assess the effect of a single SM (i.e. SM vs. sham) on cardiovascular autonomic activity. Also, we assessed the relationship between cardiovascular autonomic activity and level of pain threshold after the interventions.

Method

We conducted a randomized, cross-over, sham-controlled trial on healthy first-year chiropractic students comprising two experimental sessions separated by 48 h. During each session, subjects received, in a random order, either a thoracic SM or a sham manipulation. Cardiovascular autonomic activity was assessed using heart rate and systolic blood pressure variabilities. Pain sensitivity was assessed using pressure pain threshold. Measurements were performed at baseline and repeated three times (every 12 min) during the post intervention period. Participants and outcome assessors were blinded. The effect of the SM was tested with linear mixed models. The relationship between autonomic outcomes and pressure pain threshold was tested with bivariate correlations.

Results

Fifty-one participants were included, forty-one were finally analyzed. We found no statistically significant difference between SM and sham in cardiovascular autonomic activity post intervention. Similarly, we found no post-intervention relationship between cardiovascular autonomic activity and pressure pain threshold.

Conclusion

Our results suggest that a single SM of the thoracic spine has no specific effect on cardiovascular autonomic activity. Also, we found no relationship between cardiovascular autonomic activity and pressure pain threshold after the SM. Further experimental research should consider the use of several markers of autonomic activity and a more comprehensive pain assessment.

Trial registration

N° NCT03273868. Registered September 6, 2017.

Neurophysiological Effects of High Velocity and Low Amplitude Spinal Manipulation in Symptomatic and Asymptomatic Humans: A Systematic Literature Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To summarize the evidence of neurophysiological effects of spinal manipulative therapy (SMT) with a high velocity low amplitude thrust (HVLA-SMT) in asymptomatic and symptomatic humans.

SUMMARY OF BACKGROUND DATA

HVLA-SMT is effective in reducing back pain, but its mode of action is not fully understood.

METHODS

A systematic literature search (until July 2018) was conducted by a professional librarian in seven databases (Medline (OvidSP), Premedline (PubMed), EMBASE, Cochrane, CINAHL, PEDro, and Scopus). Two authors selected the studies according to the a priori described criteria and scored study quality. Only controlled studies of at least moderate quality were included. Effects of HVLA-SMT on a particular outcome measure were defined as more than one study showing a significantly greater effect of HVLA-SMT compared with the control intervention.

RESULTS

From the 18 studies included (932 participants in total), there was evidence only for an association between HVLA-SMT and changes in the autonomic nervous system, reflected in changes in heart rate variability and skin conductance. Most studies focused on healthy volunteers and none related neurophysiologic changes to pain reduction.

CONCLUSION

This systematic review points to HVLA-SMT affecting the autonomic nervous system. The effects seem to depend on the spinal level of HVLA-SMT application and might differ between healthy volunteers and pain patients. There is a need for high-quality studies that include patients, well characterized for pain duration and outcome measure baseline values, and address the relation between changes in neurophysiology and pain.

LEVEL OF EVIDENCE

2.

Association between sympathoexcitatory changes and symptomatic improvement following cervical mobilisations in participants with neck pain. A double blind placebo controlled trial

BACKGROUND

sympathoexcitation observed with passive cervical mobilisations may imply activation of an endogenous pain inhibition system resulting in hypoalgesia. However, research is mostly in asymptomatic participants and there is very limited evidence of a relationship between sympathoexcitation and symptomatic improvement in people with clinical pain.

OBJECTIVE

to investigate the effects of cervical mobilisations on the sympathetic nervous system in participants with neck pain, and to explore the relationship between symptomatic improvement and sympathoexcitation.

DESIGN

double-blind randomised controlled trial.

METHOD

40 participants with neck pain (aged 20-69 years, 25 female) were randomly allocated to either cervical mobilisations or motionless placebo. Skin conductance was measured before, during, and after intervention. After interventions were completed, their credibility was assessed. Participants were classified as responders or non-responders according to global symptom change.

RESULTS

participants receiving mobilisations were more likely to be classified as responders (odds ratio: 4.33, p = 0.03) and demonstrated greater change in most outcome measures of sympathoexcitation from baseline to during the intervention but not from during to after the intervention. There was no association between sympathoexcitation and symptomatic improvement. Mobilisations and placebo were equally credible.

CONCLUSIONS

These findings suggest sympathoexcitatory changes may be caused by an orienting response unrelated to the activation of an endogenous pain inhibition system Alternatively, the observed lack of an association may be explained by the existence of various mechanisms for pain relief. This study used single outcome measures of sympathoexcitation and symptomatic improvement and other measures may reveal different things. CLINICALTRIALS.

GOV NUMBER

M10/2016/095.

Functional Magnetic Resonance Imaging of Cerebral Hemodynamic Responses to Pain Following Thoracic Thrust Manipulation in Individuals With Neck Pain: A Randomized Trial

OBJECTIVE

The purpose of this study was to examine whether cerebral activation in response to noxious mechanical stimuli varies with thrust manipulation (TM) when compared with sham manipulation (SM) as measured by blood oxygenation level-dependent functional magnetic resonance imaging.

METHODS

Twenty-four volunteers (67% female) with complaints of acute or subacute mechanical (nontraumatic) neck pain satisfied eligibility requirements and agreed to participate. Participants were randomized to receive TM to the thoracic spine or SM, and then underwent functional magnetic resonance scanning while receiving noxious stimuli before and after TM or SM. An 11-point numeric pain rating scale was administered pre- and postmanipulation for neck pain and to determine perceptions of pain intensity with respect to neck pain and mechanical stimuli. Blood oxygenation level-dependent functional magnetic resonance imaging recorded the cerebral hemodynamic response to the mechanical stimuli.

RESULTS

Imaging revealed significant group differences, with those individuals in the manipulation group exhibiting increased areas of activation (postmanipulation) in the insular and somatosensory cortices and individuals in the sham group exhibiting greater areas of activation in the precentral gyrus, supplementary motor area, and cingulate cortices (P < .05). However, between-group differences on the numeric pain rating scale for mechanical stimuli and for self-reported neck pain were not statistically significant.

CONCLUSIONS

This study provides preliminary level 2b evidence suggesting cortical responses in patients with nontraumatic neck pain may vary between thoracic TM and a sham comparator.

A Longitudinal Observational Clinical Study of Neurophysiological and Patient-Reported Responses to a Program of Physiotherapy for Acute and Subacute Low Back Pain

OBJECTIVES

The purpose of this study was to document the baseline neurophysiological status (skin conductance activity levels) of patients presenting for physiotherapy with acute and subacute low back pain (symptoms of up to 12 weeks' duration) and to observe the magnitude and direction of sympathetic nervous system (SNS) changes (skin conductance responses [SCRs]) occurring as a result of receiving guideline-endorsed physiotherapy treatment.

METHODS

A pragmatic, prospective, longitudinal, observational study recording SNS skin conductance (SC) responses and patient reported outcome measure changes to a program of guideline-endorsed physiotherapy treatment for low back pain symptoms of up to 12 weeks' duration. Sixty patients received a guideline-endorsed physiotherapy treatment program. Continuous neurophysiological recordings of SC activity levels were taken throughout each treatment. Patient reported outcome measure data were extracted from inception, midpoint, and discharge. Within and between treatment analyses determined the nature of SC changes and correlations to longitudinal changes in pain and function. Skin conductance changes were measured within and between treatment episodes at treatment inception, midpoint, and discharge and observed correlations between the magnitude of SCRs, pain abatement (numeric pain rating scale), and functional restoration (Oswestry Disability Index).

RESULTS

Skin conductance changes were significant during all "treatment" periods (P = .044), with the greatest magnitude of sympathoexcitatory responses occurring at inception (219%). The treatment modality providing the maximum SNS response was a high-velocity lumbar rotation manipulation. Positive correlations were identified between SCRs, Oswestry Disability Index improvements (r = 0.82, P < .0005), and pain abatement (r = 0.459, P < .0005).

CONCLUSIONS

Patients with low back pain exhibited neurophysiological treatment responses indicative of a symptom-related neuroplastic state of dorsal horn sensitization that may be receptive to early manual therapy intervention.

Predictive factors for reporting adverse events following spinal manipulation in randomized clinical trials - secondary analysis of a systematic review

While spinal manipulative therapy (SMT) is recommended for the treatment of spinal disorders, concerns exist about adverse events associated with the intervention. Adequate reporting of adverse events in clinical trials would allow for more accurate estimations of incidence statistics through meta-analysis. However, it is not currently known if there are factors influencing adverse events reporting following SMT in randomized clinical trials (RCTs). Thus our objective was to investigate predictive factors for the reporting of adverse events in published RCTs involving SMT. The Physiotherapy Evidence Database (PEDro) and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for RCTs involving SMT. Domains of interest included: sample size; publication date relative to the 2010 CONSORT statement; risk of bias; the region treated; and number of intervention sessions. 7398 records were identified, of which 368 articles were eligible for inclusion. A total of 140 (38.0%) articles reported on adverse events. Articles were more likely to report on adverse events if they possessed larger sample sizes, were published after the 2010 CONSORT statement, had a low risk of bias and involved multiple intervention sessions. The region treated was not a significant predictor for reporting on adverse events. Predictors for reporting on adverse events included larger sample size, publication after the 2010 CONSORT statement, low risk of bias and trials involving multiple intervention sessions. We recommend that researchers focus on developing robust methodologies and participant follow-up regimens for RCTs involving SMT.

An investigation into the effects of applying a lumbar Maitland mobilisation at different frequencies on sympathetic nervous system activity levels in the lower limb

BACKGROUND

Oscillatory Maitland mobilisations are commonly used in the management of lower back pain with research suggesting that mobilisations at 2 Hz may excite the sympathetic nervous system (SNS) more than sustained pressure glides or 0.5 Hz oscillatory mobilisations.

OBJECTIVES

Investigate the effects of increasing the oscillation frequency greater than 2 Hz.

DESIGN

A double-blind, placebo-controlled, independent group experimental design.

METHOD

Sixty healthy male volunteers were randomly allocated to one of four groups; a control group (no contact), placebo group (sustained static pressure to L4 vertebra), and two intervention groups receiving a centrally applied postero-anterior mobilisation applied at either 2 Hz or 3 Hz for three 1-min periods. SNS activity was recorded by a blinded data collector by continuous skin conductance (SC) activity levels in the feet using a Biopac MP35 electrodermal amplifier. Participants were blinded to their group allocation which was further validated by a post-experiment questionnaire (p > 0.05).

RESULTS

The magnitude of sympathoexcitatory response was greatest for the 3 Hz mobilisation (20%) compared with the 2 Hz mobilisation (12%), placebo (-1%) and control conditions (3%). Only the 3 Hz group demonstrated statistical significance when compared to placebo intervention (p = 0.002), and the control group (p = 0.02).

CONCLUSION

SC changes reflect those of previous studies using lumbar mobilisations at 2 Hz, however the 3 Hz group was found to have a greater magnitude of effect worthy of consideration within research and clinical settings. These findings provide preliminary evidence to support the use of 3 Hz oscillatory mobilisations to affect a greater magnitude of SNS activity than those previously reported (0.5, 1.5 and 2 Hz).