Effects of manual therapy on pain

Last Update Posted : November 14, Study Description. Detailed Description:. MedlinePlus related topics: Fibromyalgia. FDA Resources. Arms and Interventions. Outcome Measures.

Primary Outcome Measures : Change in Heart rate variability [ Time Frame: 10 minutes before, during and after intervention ] Heart rate variability HRV will be assessed as an indicator of autonomic regulation. Psychological well-being will be assessed by the Ryff scale. Eligibility Criteria.

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More Information. National Library of Medicine U. National Institutes of Health U. Department of Health and Human Services. While helpful in directing clinical practice, an explanation is lacking as to why such patterns of signs and symptoms predicts successful clinical outcomes. Subsequently, the biological plausibility of current clinical prediction rules may not be established leading to concern for chance associations rather than causation. Highlighting this concern, only one clinical prediction rule Flynn et al.

An understanding of the mechanisms behind MT could assist in the identification of individuals likely to respond to MT by allowing a priori hypotheses as to pertinent predictive factors for future clinical prediction rules and a better understanding of the factors which are determined as predictive.

A second benefit of the identification of MT mechanisms is the potential for increased acceptance of these techniques by health care providers. The lack of an identifiable mechanism of action for MT may limit the acceptability of these techniques as they may be viewed as less scientific. Knowledge of mechanisms may promote more appropriate use of MT by healthcare providers.

The intention of this manuscript is to present a comprehensive model to guide future studies of MT mechanisms. For our purposes, MT includes a variety of techniques used in clinical practice for the treatment of musculoskeletal pain which target the skeletal system, soft tissue, and nervous system Table 1.

Passive, combined movement of the spine and extremities, within their normal range of motion, in ways to elongate or tension specific nerves. Classification of manual therapy techniques referenced in manuscript along with specific examples of each. Proposed model is general and accounts for all techniques regardless of their theorized anatomical emphasis. A limitation of the current literature is the failure to acknowledge the potential for a combined effect of these mechanisms.

Combined effects may be important to consider as the biomechanical parameters of a given MT may produce unique or dose dependent neurophysiological responses. For example, associated hypoalgesic response McLean et al.

Additionally, prior studies often focus on a single neurophysiological mechanism without consideration for competing explanations.

While helpful in establishing the groundwork for the mechanistic study of MT, conclusions based on studies designed in this fashion may fail to consider other potentially pertinent mechanisms. Psychological factors have an observed association with muscular response in individuals with low back pain Thomas et al.

Subsequently, outcomes reported in the prior studies DeVocht et al. A consideration of the interaction between biomechanical and multiple potential neurophysiological effects necessitates a comprehensive model to synthesize the current literature and direct future research.

We propose the following model which provides a compilation of the existing mechanistic literature of MT as a framework for interpreting current and conducting future mechanistic research Figure 1.

Briefly, this model suggests a mechanical stimulus initiates a number of potential neurophysiological effects which produce the clinical outcomes associated with MT in the treatment of musculoskeletal pain. Figure Key: The model suggests a transient, mechanical stimulus to the tissue produces a chain of neurophysiological effects. Solid arrows denote a direct mediating effect.

Biomechanical effects are associated with MT as motion has been quantified with joint biased MT Colloca et al. First, only transient biomechanical effects are supported by studies which quantify motion Colloca et al. Second, biomechanical assessment is not reliable. Palpation for position and movement faults has demonstrated poor reliability Seffinger et al.

Third, MT techniques lack precision as nerve biased techniques are not specific to a single nerve Kleinrensink et al. Additionally, different kinetic parameters are observed between clinicians in the performance of the same technique Hessell et al. Finally, studies have reported improvements in signs and symptoms away from the site of application such as treating cervical pain with MT directed to the thoracic spine Cleland et al.

Collectively, the literature suggests a biomechanical effect of MT; however, lasting structural changes have not been identified, clinicians are unable to reliably identify areas requiring MT, the forces associated with MT are not specific to a given location and vary between clinicians, choice of technique does not seem to affect outcomes, and sign and symptom responses occur in areas separate from the region of application.

The effectiveness of MT despite the inconsistencies associate with a purported biomechanical mechanism suggests that additional mechanisms may be pertinent. Subsequently, we suggest, that as illustrated by the model, a mechanical force is necessary to initiate a chain of neurophysiological responses which produce the outcomes associated with MT. The proposed model accounts for the complex interactions of both the peripheral and central nervous system which comprise the pain experience.

Current mechanistic studies of MT in humans are frequently unable to directly observe the central or peripheral nervous system. Subsequently, in the absence of direct observation, conclusions are drawn from associated neurophysiological responses which indirectly implicate specific mechanisms. Studies have measured associated responses of hypoalgesia and sympathetic activity following MT to suggest a mechanism of action mediated by the periaquaductal gray Wright, and lessening of temporal summation following MT to suggest a mechanism mediated by the dorsal horn of the spinal cord George et al.

Musculoskeletal injuries induce an inflammatory response in the periphery which initiates the healing process and influences pain processing. Inflammatory mediators and peripheral nociceptors interact in response to injury and MT may directly affect this process.

For example, Teodorczyk-Injeyan et al. Finally, soft tissue biased MT has been shown to alter acute inflammation in response to exercise Smith et al. Collectively, these studies suggest a potential mechanism of action of MT on musculoskeletal pain mediated by the peripheral nervous system for which mechanistic studies may wish to account. MT may exert an effect on the spinal cord.

Direct evidence for such an effect comes from a study Malisza et al. A spinal cord response was quantified by functional MRI during light touch to the hind paw. A trend was noted towards decreased activation of the dorsal horn of the spinal cord following the MT. The model uses associated neuromuscular responses following MT to provide indirect evidence for a spinal cord mediated mechanism.

For example, MT is associated with hypoalgesia George et al. Finally, the pain literature suggests the influence of specific supraspinal structures in response to pain. Structures such as the anterior cingular cortex ACC , amygdala, periaqueductal gray PAG , and rostral ventromedial medulla RVM are considered instrumental in the pain experience. Peyron et al. Subsequently, the model considers potential supraspinal mechanisms of MT.

Direct support for a supraspinal mechanism of action of MT comes from Malisza et al. Functional MRI of the supraspinal region quantified the response of the hind paw to light touch following the injection. A trend was noted towards decreased activation of the supraspinal regions responsible for central pain processing. Additionally, variables such as placebo, expectation, and psychosocial factors may be pertinent in the mechanisms of MT Ernst, ; Kaptchuk, For example expectation for the effectiveness of MT is associated with functional outcomes Kalauokalani et al.

This comprehensive model delineates potential mechanisms associated with pain relief from MT allowing researchers to identify domains of interest their studies are designed to evaluate and potential mechanisms not adequately considered. The model is intended to highlight differing possibilities when conclusions are drawn which may be further explored in subsequent studies.

For example, studies have reported hypoalgesia following MT George et al. George et al. The model indicates that while monitoring a spinal cord mediating effect temporal summation , the potential for a peripheral or supraspinal mediating effects was not considered Figure 2. A recent study attempted to replicate these prior findings while accounting for potential supraspinal influence Bialosky et al.

Specifically, a spinal cord mediated effect was measured through an associated response of temporal summation. Additionally, a potential supraspinal mechanism expectation was manipulated by randomly assigning participants to receive an instructional set stating MT was expected to either increase, decrease, or have no effect on their pain perception.

The model pathway of this study is visualized in Figure 3. Figure Key: Proposed model pathway of study by George et al suggesting a spinal cord mediating effect of manual therapy. Bold arrows indicate suggested mechanism.

Note mediating effect is suggested to be through the spinal cord due to measurement of the associated relationship of temporal summation. Also note, the design of this study neglects to consider potential supraspinal mediated effects. Figure Key: Proposed model pathway of study by Bialosky et al which considers both a spinal cord and supraspinal mediating effect of MT.

Note mediating effect is suggested to be through both the spinal cord due to measurement of the associated relationship of temporal summation and through a supraspinal mechanism due to measurement of the associated relationship of expectation.

In addition to guiding research, the model also allows clinicians to visualize the potential multiple mechanisms likely involved in the clinical effects of MT. The clinical use of MT is frequently dependent upon a purported biomechanical mechanism in evaluation and treatment. For instance, a clinical examination may focus on locating a mal- aligned joint or a hypomobile joint or soft tissue.

A MT technique may then be used as treatment to impart a specific movement to the observed dysfunction. Clinical outcomes are then attributed to alleviation of the biomechanical fault. Such practice is common and has lead to many continuing education dollars and valuable clinic time spent in search of biomechanical dysfunction of questionable validity Seffinger et al. The model provides visualization of what the current literature suggests as mechanisms pertinent to MT and while acknowledging a biomechanical effect allows clinicians to consider other potential mechanisms in the MT evaluation and treatment of individuals with musculoskeletal pain.

The model is intended to be applicable to all forms of MT. While the biomechanical application of joint biased, soft tissue biased and nerve biased MT are different, the related neurophysiological responses are similar and adequately encompassed within the model given the current state of knowledge. The proposed model provides a platform to empirically test hypotheses related to different biomechanical and neurophysiological effects specific to types of MT, an area that is currently lacking in the literature.

The proposed comprehensive model is intended to explain the mechanisms of MT on musculoskeletal pain. Finally, this model is strictly intended to guide research questions regarding the mechanisms of MT. A body of literature already exists suggesting the effectiveness of MT. The proposed model is intended to compliment and provide underlying explanations to the existing body of literature suggesting the effectiveness of MT. A limitation in the current literature is the failure to account for the non- specific mechanisms associated with MT in the treatment of musculoskeletal pain.

A number of neurophysiological responses associated with MT are also associated with non- specific effects such as placebo Figure 4. Current study designs have not adequately accounted for non-specific effects, and subsequently, their role in the clinical outcomes associated with MT is unknown. Future mechanistic studies in MT should consider determining the influence of non- specific effects.

The model presents a guide to design future mechanistic studies so that all relevant possibilities are included. A limitation of the current mechanistic literature in MT is the failure to adequately account for non- specific effects such as placebo and expectation. Italicized references are examples of studies from the placebo and expectation literature which have reported similar neurophysiological effects as have been associated with MT.

These similarities emphasize the potential for non- specific effects to play a significant role in the mechanisms behind MT and the need to specifically address these factors in future studies. The model is based primarily on associated responses as the current body of mechanistic literature is lacking in studies which directly observe regions of interest.

As technology improves, the means to directly observe specific regions is becoming possible. In addition, if we can identify other mediators that are capable of being addressed through direct treatment e. The recognition of patient and therapist characteristics that modify treatment outcomes will also improve the application and implementation of MT approaches to the management of the pain experience by determining the psychological profile of individuals likely to benefit from these interventions and the best context in which to provide these interventions Figure 1.

MT is an effective treatment contributing to the recovery of functional capabilities, but it should be included within a multimodal approach targeting the functional recovery of the patient. Current evidence is suggesting that a multimodal approach, including MT, exercise and education, seems to provide better outcomes than MT alone. A genuine multimodal approach should include not only physical management but a consideration of the psychological and psychosocial aspects of the patient's unique pain experience.

As we continue to uncover more about the management of pain conditions using MT, especially chronic pain, it becomes more noticeable that they appear to resemble a mosaic of phenotypes that may be further influenced by genetic factors related to peripheral and central neural plasticity e.

Moving forward, investigations will continue to uncover biomarkers that underlie the complex pathophysiology of pain conditions and the transition of acute to chronic pain states. As healthcare moves toward mechanism-based personalized treatments, it will become ever more important to understand the extent to which MT influences these underlying mechanisms. In addition, studies of MT must link the many immediate changes in neurophysiological function e.

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript. National Center for Biotechnology Information , U. Pain Manag. Author information Copyright and License information Disclaimer.

This article has been cited by other articles in PMC. Abstract Manual therapy MT is a passive, skilled movement applied by clinicians that directly or indirectly targets a variety of anatomical structures or systems, which is utilized with the intent to create beneficial changes in some aspect of the patient pain experience.

Practice points. Background Manual therapies MTs are centuries old and practiced by many professions worldwide. MT is effective for managing musculoskeletal pain. Mediating factors for effectiveness of MT Biomechanical: — MT causes measurable movement in targeted tissues; — Some structural changes occur within the targeted tissues in response to MT; — Limitations to a strictly biomechanical model explaining the effectiveness of MT result from low interpractitioner reliability of application of technique parameters force and magnitude, among others.

Neurophysiological: — Immediate changes in neurophysiological function observed after MT: — Reduction in inflammatory markers; — Decreased spinal excitability and pain sensitivity; — Modification to cortical areas involved in pain processing; — Excitation of the sympathetic nervous system.

Moderating factors for effectiveness of MT Patient and provider expectation, therapeutic alliance, and context of the intervention heavily influence the clinical outcomes of MT. Future directions Additional work is needed to link immediate changes in neurophysiological measures with clinical outcomes. The appropriate dosing of MT remains undetermined. Genetic characteristics of patients may also be linked to response to MT. The pain experience The International Association for the Study of Pain defines pain as "…unpleasant sensory and emotional experience that is associated with actual or potential tissue damage or described in such terms.

Open in a separate window. Figure 1. Moderators and mediators of the pain experience resulting from manual therapy interventions. Moderating for effectiveness of MT Many of the physiological changes identified after MT may also be initiated by treatment modifiers. Future perspective MT is an effective treatment contributing to the recovery of functional capabilities, but it should be included within a multimodal approach targeting the functional recovery of the patient.

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