Neuroendocrine Response Following a Thoracic Spinal Manipulation in Healthy Men

Vertebral Subluxation and Systems Biology: An Integrative Review Exploring the Salutogenic Influence of Chiropractic Care on the Neuroendocrine-Immune System

In this paper we synthesize an expansive body of literature examining the multifaceted influence of chiropractic care on processes within and modulators of the neuroendocrine-immune (NEI) system, for the purpose of generating an inductive hypothesis regarding the potential impacts of chiropractic care on integrated physiology. Taking a broad, interdisciplinary, and integrative view of two decades of research-documented outcomes of chiropractic care, inclusive of reports ranging from systematic and meta-analysis and randomized and observational trials to case and cohort studies, this review encapsulates a rigorous analysis of research and suggests the appropriateness of a more integrative perspective on the impact of chiropractic care on systemic physiology. A novel perspective on the salutogenic, health-promoting effects of chiropractic adjustment is presented, focused on the improvement of physical indicators of well-being and adaptability such as blood pressure, heart rate variability, and sleep, potential benefits that may be facilitated through multiple neurologically mediated pathways. Our findings support the biological plausibility of complex benefits from chiropractic intervention that is not limited to simple neuromusculoskeletal outcomes and open new avenues for future research, specifically the exploration and mapping of the precise neural pathways and networks influenced by chiropractic adjustment.

Changes in biochemical markers following a spinal manipulation - a systematic review update

OBJECTIVE

The aim of this systematic review was to update the current level of evidence for spinal manipulation in influencing various biochemical markers in healthy and/or symptomatic population.

METHODS

This is a systematic review update. Various databases were searched (inception till May 2023) and fifteen trials (737 participants) that met the inclusion criteria were included in the review. Two authors independently screened, extracted and assessed the risk of bias in included studies. Outcome measure data were synthesized using standard mean differences and meta-analysis for the primary outcome (biochemical markers). The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of the body of evidence for each outcome of interest.

RESULTS

There was low-quality evidence that spinal manipulation influenced various biochemical markers (not pooled). There was low-quality evidence of significant difference that spinal manipulation is better (SMD -0.42, 95% CI - 0.74 to -0.1) than control in eliciting changes in cortisol levels immediately after intervention. Low-quality evidence further indicated (not pooled) that spinal manipulation can influence inflammatory markers such as interleukins levels post-intervention. There was also very low-quality evidence that spinal manipulation does not influence substance-P, neurotensin, oxytocin, orexin-A, testosterone and epinephrine/nor-epinephrine.

CONCLUSION

Spinal manipulation may influence inflammatory and cortisol post-intervention. However, the wider prediction intervals in most outcome measures point to the need for future research to clarify and establish the clinical relevance of these changes.

Effectiveness of spinal manipulation in influencing the autonomic nervous system - a systematic review and meta-analysis

BACKGROUND

Spinal manipulation (SM) has been hypothesized to influence the autonomic nervous system (ANS). Further, it has been proposed that the effects may vary depending on the segment manipulated. The aim of this systematic review was to synthesize the current level of evidence for SM in influencing the ANS in healthy and/or symptomatic population.

METHODS

Various databases (n = 8) were searched (inception till May 2023) and 14 trials (n = 618 participants) were included in the review. Two authors independently screened, extracted and assessed the risk of bias in included studies. The data were synthesized using standard mean differences and meta-analysis for the primary outcome measures. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of the body of evidence for each outcome of interest.

RESULTS

Overall, there was low quality evidence that SM did not influence any measure of ANS including heart rate variability (HRV), oxy-hemoglobin, blood pressure, epinephrine and nor-epinephrine. However, there was low quality evidence that cervical spine manipulation may influence high frequency parameter of HRV, indicating its influence on the parasympathetic nervous system.

CONCLUSION

When compared with control or sham interventions, SM did not alter the ANS. Due to invalid methodologies and the low quality of included studies, findings must be interpreted with great caution. Future studies are needed which employ rigorous data collection processes to verify the true physiological implications of SM on ANS.

Autonomic nervous system and endocrine system response to upper and lower cervical spine mobilization in healthy male adults: a randomized crossover trial

BACKGROUND

Cervical spine mobilizations may differentially modulate both components of the stress response, consisting of the autonomic nervous system and hypothalamic pituitary adrenal-axis, depending on whether the target location is the upper or lower cervical spine. To date, no study has investigated this.

METHODS

A randomized, crossover trial investigated the effects of upper versus lower cervical mobilization on both components of the stress response simultaneously. The primary outcome was salivary cortisol (sCOR) concentration. The secondary outcome was heart rate variability measured with a smartphone application. Twenty healthy males, aged 21-35, were included. Participants were randomly assigned to block-AB (upper then lower cervical mobilization, n = 10) or block-BA (lower than upper cervical mobilization, n = 10), separated by a one-week washout period. All interventions were performed in the same room (University clinic) under controlled conditions. Statistical analyses were performed with a Friedman's Two-Way ANOVA and Wilcoxon Signed Rank Test.

RESULTS

Within groups, sCOR concentration reduced thirty-minutes following lower cervical mobilization (p = 0.049). Between groups, sCOR concentration was different at thirty-minutes following the intervention (p = 0.018).

CONCLUSION

There was a statistically significant reduction in sCOR concentration following lower cervical spine mobilization, and between-group difference, 30 min following the intervention. This indicates that mobilizations applied to separate target locations within the cervical spine can differentially modulate the stress response.

[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.

Correlation among Routinary Physical Activity, Salivary Cortisol, and Chronic Neck Pain Severity in Office Workers: A Cross-Sectional Study

This study aimed to assess the correlation between different aspects of routinary physical activity with chronic neck pain severity indicators and salivary cortisol. This cross-sectional observational study included ninety-four office workers with non-specific chronic neck pain in the analyses. Pain related outcomes (pain intensity, pressure pain thresholds and disability), physical activity outcomes using the International Physical Activity Questionnaire, and salivary cortisol levels were evaluated. Pearson’s correlation analysis was used to investigate internal associations and regression models to explain and calculate which factors contribute to the variance of salivary cortisol and neck pain severity. Female sex (p < 0.01), sedentary behaviors (p < 0.05), and pain sensitivity (p < 0.05) were associated with greater cortisol levels (p < 0.05), but disability and pain intensity were not associated (p > 0.05). Worse disability, pain intensity, and pain pressure thresholds were also associated with lower routinary physical activity (p < 0.05). Regression models explained 20.6% of pain intensity (based on walking time to their workplace, age and pain sensitivity); 27.3% of disability (based on moderate physical activity at home, vigorous physical activity during leisure time and pain sensitivity); 54.2% of pain sensitivity (based on cycling time from home to their workplace, gender and vigorous activity during leisure time) and 38.2% of salivary cortisol concentration (based on systolic pressure, vigorous activity at work and both moderate and vigorous activity at home). Our results demonstrated the association between salivary cortisol concentration with moderate and vigorous physical activity, sitting time at work, and PPTs. However, salivary cortisol was not associated with disability or pain intensity.

Thoracic Spinal Manipulation Effect on Neuroendocrine Response in People With Achilles Tendinopathy: A Randomized Crossover Trial

OBJECTIVE

The purpose of the present study was to determine the neuroendocrine response after a thoracic spinal manipulation in people with Achilles tendinopathy.

METHODS

This was a randomized 2-sequence, 2-period crossover trial. A total of 24 participants, mean (standard deviation) age of 48 (7) years, with a diagnosis of Achilles tendinopathy (>3 mo) were randomly assigned into sequence 1 (sham intervention and then thoracic spinal manipulation) or sequence 2 (thoracic spinal manipulation and then sham intervention). The trial was conducted at a university laboratory with a washout period of 1 week. The primary outcome measure was the testosterone/cortisol (T/C) ratio (salivary samples). The secondary outcome measures included heart rate variability (measured with electrocardiography) and total oxygenation index (nmol/L) of calf muscle and Achilles tendon (measured with near-infrared spectroscopy). A 2-way mixed-model analysis of variance was performed. The statistic of interest was the condition by time interaction.

RESULTS

A statistically significant condition by time interaction was found for the T/C ratio (mean difference: -0.16; confidence interval: -0.33 to 0.006; interaction: P < .05) and the total oxygenation index (mean difference: 1.35; confidence interval: -1.3 to 4.1; interaction: P < .05) of calf muscle but not for Achilles tendon (P = .6); however, no difference was found for heart rate variability (P = .5).

CONCLUSION

In people with Achilles tendinopathy, thoracic spinal manipulation resulted in immediate increase in the total oxygenation index in the calf muscle followed by an increase in the T/C ratio 6 hours post-intervention.

The Potential Mechanisms of High-Velocity, Low-Amplitude, Controlled Vertebral Thrusts on Neuroimmune Function: A Narrative Review

The current COVID-19 pandemic has necessitated the need to find healthcare solutions that boost or support immunity. There is some evidence that high-velocity, low-amplitude (HVLA) controlled vertebral thrusts have the potential to modulate immune mediators. However, the mechanisms of the link between HVLA controlled vertebral thrusts and neuroimmune function and the associated potential clinical implications are less clear. This review aims to elucidate the underlying mechanisms that can explain the HVLA controlled vertebral thrust--neuroimmune link and discuss what this link implies for clinical practice and future research needs. A search for relevant articles published up until April 2021 was undertaken. Twenty-three published papers were found that explored the impact of HVLA controlled vertebral thrusts on neuroimmune markers, of which eighteen found a significant effect. These basic science studies show that HVLA controlled vertebral thrust influence the levels of immune mediators in the body, including neuropeptides, inflammatory markers, and endocrine markers. This narravtive review discusses the most likely mechanisms for how HVLA controlled vertebral thrusts could impact these immune markers. The mechanisms are most likely due to the known changes in proprioceptive processing that occur within the central nervous system (CNS), in particular within the prefrontal cortex, following HVLA spinal thrusts. The prefrontal cortex is involved in the regulation of the autonomic nervous system, the hypothalamic-pituitary-adrenal axis and the immune system. Bi-directional neuro-immune interactions are affected by emotional or pain-related stress. Stress-induced sympathetic nervous system activity also alters vertebral motor control. Therefore, there are biologically plausible direct and indirect mechanisms that link HVLA controlled vertebral thrusts to the immune system, suggesting HVLA controlled vertebral thrusts have the potential to modulate immune function. However, it is not yet known whether HVLA controlled vertebral thrusts have a clinically relevant impact on immunity. Further research is needed to explore the clinical impact of HVLA controlled vertebral thrusts on immune function.

Effects of Osteopathic T9-T10 Vertebral Manipulation in Tonsillitis: A Randomized Clinical Trial

This study aimed to determine whether osteopathic manipulation of the T9-T10 vertebrae improves the evolution of tonsillitis. A randomized, stratified, controlled clinical trial with blinded patients, evaluator and data analyst was performed. The patients in the control group (CG) underwent a "sham" manipulation. A high-speed, low-amplitude technique was applied to the T9-T10 vertebrae in the osteopathic manipulative group (OMG) patients. The number of days needed to resolve the tonsillitis was significantly lower (p = 0.025) in the OMG (2.03 ± 0.95 days) than the CG (2.39 ± 0.82 days). Additionally, the number of episodes of tonsillitis after the treatment decreased significantly more in the OMG (0.8 ± 1.88 episodes/year in total) than the CG (2 ± 2.12) (p = 0.005). In the OMG, 60.8% had no recurrences of tonsillitis, compared to 22.5% of the CG, in the following year (χ2 (1) = 15.57, p < 0.001). No patients reported adverse effects. It has been concluded that during an episode of tonsillitis, the number of days to resolution was significantly lower after the application of an osteopathic manipulation of the T9-T10 vertebrae, compared to a sham manipulation. The number of subsequent year tonsillitis episodes was greatly reduced in both groups, significantly more in the OMG than in the CG patients.

Neurophysiological mechanisms of chiropractic spinal manipulation for spine pain

Together, neck pain and back pain are the first cause of disability worldwide, accounting for more than 10% of the total years lived with disability. In this context, chiropractic care provides a safe and effective option for the management of a large proportion of these patients. Chiropractic is a healthcare profession mainly focused on the spine and the treatment of spinal disorders, including spine pain. Basic studies have examined the influence of chiropractic spinal manipulation (SM) on a variety of peripheral, spinal and supraspinal mechanisms involved in spine pain. While spinal cord mechanisms of pain inhibition contribute at least partly to the pain-relieving effects of chiropractic treatments, the evidence is weaker regarding peripheral and supraspinal mechanisms, which are important components of acute and chronic pain. This narrative review highlights the most relevant mechanisms of pain relief by SM and provides a perspective for future research on SM and spine pain, including the validation of placebo interventions that control for placebo effects and other non-specific effects that may be induced by SM. SIGNIFICANCE: Spinal manipulation inhibits back and neck pain partly through spinal segmental mechanisms and potentially through peripheral mechanisms regulating inflammatory responses. Other mechanisms remain to be clarified. Controls and placebo interventions need to be improved in order to clarify the contribution of specific and non-specific effects to pain relief by spinal manipulative therapy.

Assessment of Studies Evaluating Spinal Manipulative Therapy and Infectious Disease and Immune System Outcomes: A Systematic Review

IMPORTANCE

Claims that spinal manipulative therapy (SMT) can improve immune function have increased substantially during the COVID-19 pandemic and may have contributed to the rapid spread of both accurate and inaccurate information (referred to as an infodemic by the World Health Organization).

OBJECTIVE

To identify, appraise, and synthesize the scientific literature on the efficacy and effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes in patients with infectious disease and to examine the association between SMT and selected immunological, endocrine, and other physiological biomarkers.

EVIDENCE REVIEW

A literature search of MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Index to Chiropractic Literature, the Cochrane Central Register of Controlled Trials, and Embase was conducted from inception to April 15, 2020. Randomized clinical trials and cohort studies were included. Eligible studies were critically appraised, and evidence with high and acceptable quality was synthesized using the Synthesis Without Meta-Analysis guideline.

FINDINGS

A total of 2593 records were retrieved; after exclusions, 50 full-text articles were screened, and 16 articles reporting the findings of 13 studies comprising 795 participants were critically appraised. The literature search found no clinical studies that investigated the efficacy or effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes among patients with infectious disease. Eight articles reporting the results of 6 high- and acceptable-quality RCTs comprising 529 participants investigated the effect of SMT on biomarkers. Spinal manipulative therapy was not associated with changes in lymphocyte levels or physiological markers among patients with low back pain or participants who were asymptomatic compared with sham manipulation, a lecture series, and venipuncture control groups. Spinal manipulative therapy was associated with short-term changes in selected immunological biomarkers among asymptomatic participants compared with sham manipulation, a lecture series, and venipuncture control groups.

CONCLUSIONS AND RELEVANCE

In this systematic review of 13 studies, no clinical evidence was found to support or refute claims that SMT was efficacious or effective in changing immune system outcomes. Although there were limited preliminary data from basic scientific studies suggesting that SMT may be associated with short-term changes in immunological and endocrine biomarkers, the clinical relevance of these findings is unknown. Given the lack of evidence that SMT is associated with the prevention of infectious diseases or improvements in immune function, further studies should be completed before claims of efficacy or effectiveness are made.

The immediate effect of lumbopelvic manipulation on knee pain, knee position sense, and balance in patients with patellofemoral pain: A randomized controlled trial

BACKGROUND

Patellofemoral pain (PFP) is a common musculoskeletal disorder. Quadriceps and core muscle neuromuscular control impairments are frequently associated with PFP. Lumbopelvic manipulation (LPM) has been shown to improve quadriceps and core muscle activation and decrease their inhibition, but changes in balance and knee joint position sense (JPS) after this intervention remain unknown.

OBJECTIVE

To determine whether LPM decreases knee pain and JPS error and increases balance performance in patients with PFP.

DESIGN

Randomized controlled trial.

SETTING

Biomechanics laboratory at a rehabilitation science research center.

METHODS

Forty-four patients with PFP participated in this study that randomly divided into two equal groups. One group received LPM and the other received sham LPM (positioning with no thrust) in a single session. At baseline and immediately after the intervention, the outcomes of pain using a visual analog scale, balance using the modified star excursion balance test (mSEBT), and JPS at 20° and 60° of knee flexion using a Biodex dynamometer.

RESULTS

There was a statistically significant improvement in pain, balance control (anterior direction) and JPS in the LPM group immediately after the intervention. In addition, we observed significant differences between groups in pain, balance control (anterior direction) and JPS at 60° of knee flexion immediately after the intervention.

CONCLUSION

A single session of LPM immediately improved balance control, knee JPS, and pain in patients diagnosed with PFP.

CLINICAL REHABILITATION IMPACT

Findings suggest that LPM may be used as a therapeutic tool for immediate improvement of symptoms of PFP. However, more research is needed to determine long term results.

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.

Feasibility and effectiveness of thoracic spine mobilization on sympathetic/parasympathetic balance in a healthy population - a randomized controlled double-blinded pilot study

Background

Physiotherapists often use thoracic spine mobilization (TSM) to reduce pain in patients with back disorders via a reduction of sympathetic activity. There is a "trade-off" in the activity of the sympathetic and parasympathetic nervous system activity. A sympathetic/parasympathetic balance (SPB) is needed to guarantee body homeostasis. However, body homeostasis is seldom considered as an aim of the treatment from the perspective of most physiotherapists. Strong empirical evidence for the effects of TSM on the SPB is still lacking.Some studies showed that spinal manipulation may yield beneficial effects on SPB. Therefore, it could be hypothesized that TSM is feasible and could influence SPB reactions. The primary aim was to describe the participants' adherence to the intervention and to the measurement protocol, to identify unexpected adverse events (UAE) after TSM, to evaluate the best method to measure SPB parameters (heart rate variability (HRV), blood pressure (BP), heart rate (HR), skin perfusion and erythema) and to estimate the investigation procedure. The secondary aim was to assess the effects of TSM on SPB parameters in a small sample of healthy participants.

Methods

This crossover pilot study investigated TSM using posterior-anterior mobilization (PAM) and anterior-posterior mobilization (APM) on segments T6 to T12 in twelve healthy participants during two consecutive days. To evaluate feasibility, the following outcomes were assessed: adherence, UAE, data collection and data analysis. To evaluate the effect of TSM on SPB, HRV, BP, HR, skin perfusion and erythema were measured.

Results

The adherence was 100%. No UAE were reported. PAM showed larger effect sizes compared to APM in many secondary variables.

Conclusions

Although 100% maximal adherence was reached and no UAE were observed, data recording in future studies should be done during a second time interval while the data transfer from device to the computer software should occur immediately after completion of each participant's measurement. The results of this pilot study suggest that PAM can reduce HRV HF and HRV ratio LF/HF and increase HR.

Trial registration

ClinicalTrail.gov (NCT02832141).

Molecular foundations of chiropractic therapy

Background and aim: Alternative medicine is a broad term used to encompass different therapies, including chiropractic. Chiropractic was called “a science of healing without drugs” by its founder, David Daniel Palmer. It is based on the idea that the body has a powerful self-healing ability and that there is a relationship between body structure and function that affects health. In particular, chiropractic assumes that the nervous system controls the human body through nerves branching from the vertebral column and spinal cord. Researchers do not fully understand how chiropractic therapies affect pain, but chiropractic is widely used today to treat chronic pain, such as back pain. Different studies with animal models have demonstrated that chiropractic therapies mediate neuroplasticity, specifically through modulation of neurotrophins. No studies have yet been published on interaction between neurotrophin gene polymorphisms and chiropractic treatment. Methods: We searched PubMed with the following keywords: chiropractic, neuroplasticity, neurotrophin gene polymorphism for a panorama of on the molecular mechanisms of chiropractic therapy. Results: From the material collected, we identified a set of genes and some functional polymorphisms that could be correlated with better response to chiropractic therapy. Conclusions: Further association studies will be necessary to confirm hypotheses of a correlation between single nucleotide polymorphisms in specific genes and better response to chiropractic therapy. (www.actabiomedica.it)

The Effects Induced by Spinal Manipulative Therapy on the Immune and Endocrine Systems

Background and Objectives: Spinal manipulations are interventions widely used by different healthcare professionals for the management of musculoskeletal (MSK) disorders. While previous theoretical principles focused predominantly on biomechanical accounts, recent models propose that the observed pain modulatory effects of this form of manual therapy may be the result of more complex mechanisms. It has been suggested that other phenomena like neurophysiological responses and the activation of the immune-endocrine system may explain variability in pain inhibition after the administration of spinal manipulative therapy (SMT). The aim of this paper is to provide an overview of the available evidence supporting the biological plausibility of high-velocity, low-amplitude thrust (HVLAT) on the immune-endocrine system. Materials and Methods: Narrative critical review. An electronic search on MEDLINE, ProQUEST, and Google Scholar followed by a hand and "snowballing" search were conducted to find relevant articles. Studies were included if they evaluated the effects of HVLAT on participants' biomarkers Results: The electronic search retrieved 13 relevant articles and two themes of discussion were developed. Nine studies investigated the effects of SMT on cortisol levels and five of them were conducted on symptomatic populations. Four studies examined the effects of SMT on the immune system and all of them were conducted on healthy individuals. Conclusions: Although spinal manipulations seem to trigger the activation of the neuroimmunoendocrine system, the evidence supporting a biological account for the application of HVLAT in clinical practice is mixed and conflicting. Further research on subjects with spinal MSK conditions with larger sample sizes are needed to obtain more insights about the biological effects of spinal manipulative therapy.

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.

The acute effects of joint manipulative techniques on markers of autonomic nervous system activity: a systematic review and meta-analysis of randomized sham-controlled trials

Background

The autonomic nervous system (ANS) interests many chiropractors and manual therapists, because joint manipulative techniques (JMT), e.g. high velocity low amplitude (HVLA) manipulations and mobilizations, appear to produce acute changes in ANS mediated physiology. The complexity of this issue justifies a systematic critical literature review.

Objective

To review the literature comparing the acute changes in markers of ANS activity between JMT applied on spinal or peripheral joints and a sham procedure in healthy or symptomatic subjects.

Method

We searched PsycINFO, PEDro, PubMed, Cochrane library, EMBASE, and Medline up to December 2017. We updated the search with PubMed, Cochrane library, EMBASE, and Medline including July 2018. Inclusion criteria were: randomized sham-controlled trials assessing the effect of JMT on markers of ANS activity; manually applied JMT, regardless of technique, applied on either healthy or symptomatic humans; outcome measurements recorded at baseline and repeated during and/or after interventions. Selection of articles and data extraction were performed independently by two reviewers. The quality of studies was assessed using the Cochrane ‘risk of bias’ tool and a technical check-list. Results were reported narratively with some meta-analyses. The Cochrane GRADE approach was used to assess the certainty of evidence.

Results

Twenty-nine of 2267 studies were included in the synthesis. Mobilizations (oscillatory technique) probably produce an immediate and short-term, bilateral increase in skin sympathetic nerve activity (reflected by an increase in skin conductance) regardless of the area treated (moderate-certainty evidence). It is uncertain whether the sympathetic arousal also explains an increase in respiratory rate (very low-certainty evidence). Our evaluation of the literature suggests that spinal sustained apophyseal glides (SNAGs) mobilization and HVLA manipulation of the spine may have no acute effect on the studied markers of ANS activity (very low- to low-certainty evidence).

Conclusion

Some types of mobilizations probably produce an immediate and short-term, statistically significant increase in skin sympathetic nerve activity when compared to a sham procedure, whereas spinal SNAGs and spinal HVLA techniques may have no acute effect on the studied markers of ANS activity. No region-specific results were noted. The literature suffers from several shortcomings, for which reason we strongly suggest further research.

Electronic supplementary material

The online version of this article (10.1186/s12998-019-0235-1) contains supplementary material, which is available to authorized users.

Endocrine response after cervical manipulation and mobilization in people with chronic mechanical neck pain: a randomized controlled trial

BACKGROUND

Most of the research on the effects of spinal manipulation on endocrine function has been done on healthy subjects and has yielded contradictory results. The potential role of cervical manual therapy intervention in order to induce changes in the endocrine system has not yet been investigated.

AIM

The aim of this trial is to compare the effects on salivary cortisol levels and clinical outcomes of cervical manipulation versus cervical mobilization or sham manipulation in patients with chronic mechanical neck pain.

DESIGN

Randomized controlled trial.

SETTING

University of Alcala de Henares: outpatient (referrals from office workers).

POPULATION

A total of 83 patients with chronic mechanical neck pain.

METHODS

Participants were randomized to receive one session of cervical manipulation, cervical mobilization, or sham manipulation. The measured variables were salivary cortisol levels, neck pain and disability, pressure pain thresholds (PPT), and cervical range of motion (ROM). They were obtained at baseline, immediately after treatment (except neck disability), and at one-week follow-up (except cortisol).

RESULTS

A significant and comparable increase in cortisol levels was observed immediately after cervical manipulation and mobilization (both P<0.001). Neck disability improved to a similar degree in the cervical manipulation and mobilization groups at the one-week follow-up (both P<0.001). Neck pain was reduced immediately after cervical manipulation (P<0.001), cervical mobilization (P=0.001), and sham manipulation (P<0.001). There were no significant changes in most ROM directions after either treatment. No significant interaction effect was observed for PPT.

CONCLUSIONS

Cervical manipulation and mobilization resulted in a similar increase in cortisol concentrations immediately post-treatment in people with chronic mechanical neck pain. Supraspinal mechanisms may thus play a role in the hypoalgesic effects that follow the application of both interventions.

CLINICAL REHABILITATION IMPACT

The increase in cortisol levels was similar with cervical manipulation and mobilization so induced stress levels can be similar in both interventions.

Utilization of manual therapy to the lumbar spine in conjunction with traditional conservative care for individuals with bilateral lower extremity complex regional pain syndrome: A case series

Background and purpose: Conservative therapies for complex regional pain syndrome (CRPS) have traditionally focused on exercise and desensitization techniques targeted at the involved extremity. The primary purpose of this case series is to report on the potential benefit of utilizing manual therapy to the lumbar spine in conjunction with traditional conservative care when treating patients with lower extremity CRPS.Case description: Two patients with the diagnosis of lower extremity CRPS were treated with manual therapy to the lumbar spine in conjunction with education, exercise, desensitization, and soft tissue techniques for the extremity.Outcomes: Patient 1 received 13 sessions over 6 weeks resulting in a 34-point improvement in oswestry disability index (ODI) and 35-point improvement in lower extremity functional scale (LEFS). Patient 2 received 21 sessions over 12 weeks resulting in a 28-point improvement in ODI and a 41-point improvement in LEFS.Discussion: Both patients exhibited reductions in pain and clinically meaningful improvements in function. Manual therapies when applied to the lumbar spine in these patients as part of a comprehensive treatment plan resulted in improved spinal mobility, decreased pain, and reduction is distal referred symptoms. Although one cannot infer a cause and effect relationship from a case series, this report identifies meaningful clinical outcomes potentially associated with manual physical therapy to the lumbar spine for two patients with complex regional pain syndrome type 1.