Chronic pain mechanisms encompass a complicated array of different processes (eg, genetics, neurophysiology, psychology, and biomechanics), each capable of contributing to clinical manifestations and symptoms. For OMM to be effective, similar symptoms in different patients may require dissimilar treatment plans that focus on differing local, spinal, and supraspinal targets. For example, chronic pain initiated by peripheral trauma may result when supraspinal structures continue to respond as if the peripheral tissues were actively injured. In other chronic conditions like fibromyalgia, the process may reflect an autonomic dysregulatory phenomenon or a dysfunction of descending antinociception pathways. Other conditions such as myofascial trigger points (MTrPs) demonstrate specific peripheral dysfunction at a spinal level perpetuated by nonspecific biomechanical factors, eg, untreated postural strain, or through viscerosomatic reflexes. 

In many cases, chronic pain pathways involving allodynia (generalized lowered thresholds to pain) develop as changing gene expression allows silent receptors to become active in the spinal cord, or when facilitatory modulation results in what is called “spinal cord learning.”^7,8 In each case, the patient may simply present with persistent pain. 

Therefore, rational OMT of patients with persistent pain cannot have a singular focus, nor can it be treated as a static phenomenon. In formulating multimodal treatment plans, OMM approaches embrace body unity principles and integrate palpation and OMT techniques into each patient's prescription. Choices concerning OMT techniques and goals depend on each individual's unique pain presentation, the suspected pathways involved in that presentation, and the regions diagnosed as containing somatic dysfunction. 

A total review of diagnostic regimens and therapeutic options for persistent pain is beyond the scope of this article. Therefore, this article provides a concise overview of the OMM paradigm and introduces a general algorithm for pain management. Discussion of persistent pain management is limited to generalities that concern the integration of osteopathic principles and practice (OPP) in the use of OMT. Where pertinent, specific common chronic pain presentations are described as examples supporting the algorithm (Figure 1). 

When patients present with chronic pain, especially pain that persists despite seemingly appropriate care, an algorithm (Figure 1) can suggest an approach for applying OPP and OMT. It is structured to identify and address frequently overlooked underlying etiologies included in an osteopathic differential diagnosis as well as the persistent tangible and holistic impact of pain on the body unit. Evaluation of the patient's capability to mount a homeostatic response and the underlying pathophysiologic status as interpreted by components of palpated somatic dysfunction guide the physician's timing for implementing OMM treatment strategies. 

Treatment protocols formulated from this algorithm incorporate the interdependence of all tenets of osteopathic medicine and result in an individually designed prescription to address each patient with persistent pain. 

Certain somatic findings have been consistently documented in various persistent pain conditions. Depending on the condition, the somatic dysfunction may be causative, reflexive, reactive, or perpetuating, or a combination. Thus, differential diagnoses and treatment considerations depend on both the specific region and underlying pathophysiology involved. The algorithm (Figure 1) contains generalities taking these factors and structure-function interrelationships into consideration. 

An osteopathic palpatory examination often provides clues to the underlying mechanism of injury.² Such palpatory insights lead to further questions, examinations, and tests designed to identify structural factors associated with specific pain generators or those that may interfere with certain self-healing mechanisms. The findings lead the physician to explore functional demand issues associated with potential mechanisms of repeated injury or of cumulative microtrauma resulting from postural, habitual, or occupational ergonomic stresses. 

One way to determine whether a given structure or somatic dysfunction is a primary cause of significant discomfort is to determine if it is a “pain generator” tissue. Comparing quality, anatomic location, and unique referral distribution with known sclerotomal, myotomal, and neurologic pain maps increases the chance of locating a pain generator. Often, such diagnoses are confirmed by an effective therapeutic response, even temporarily, to local anesthetic injection or manual correction of dysfunction. 

Sclerotomal tissues (skeletal, arthrodial, and ligamentous generators) typically mediate pain described as being “deep, dull, and toothache-like.” Sclerotomal pain patterns are frequently overlooked because they may project some distance from their pain generators and are infrequently taught to osteopathic physicians. The “Glossary of Osteopathic Terminology” contains sclerotomal maps relating spinal segmental levels to sclerotomal appendicular pain.⁹ Figure 2 illustrates segmentally related sclerotomal examples of ligamentous pain patterns commonly seen in low back pain (LBP). Patients with ligamentous pain generators often cannot find a comfortable position and are continuously shifting position, a presentation some refer to as “theatre cocktail party syndrome.”¹⁰ 

Myotomal (muscle) pain is also poorly localized, and the patient may describe symptoms located at a significant distance from the actual lesion site. Patients typically describe myotomal pain as “achy,” “stiff,” or “crampy,” and the pain often “grabs” them. Muscle dysfunction may include latent and active MTrPs¹¹ that when overused refer pain in recognizable patterns^12,13 (Figure 3). Antigravity muscles harboring MTrPs are frequently hypertonic, whereas postural antagonist muscles demonstrate weakness to strength testing.¹⁰ Both are likely to contain taut bands demonstrating a local twitch response within the affected muscle during perpendicularly applied snapping palpatory examination. This phenomenon has been linked to the presence of segmentally related spinal reflexes (segmental facilitation).^14,15 

Peripheral myotomal pain generators can originate in a single muscle. Alternatively, multiple peripheral inputs may establish more complex patterns of muscle dysfunction. Peripheral input can also produce a central imprint that persists as a central source of pain-modifying peripheral referral patterns (somatosomatic reflex). Common myotomal patterns also include those sharing the same radicular innervation (as occurs in discogenic disease) or those muscles contributing to the same general function (as in the myotatic unit pattern occurring in an overuse syndrome). 

In structure-function considerations, osteopathic diagnostic palpation seeks to identify “any impaired or altered skeletal, arthrodial, and/or myofascial function” (viz “somatic dysfunction”⁹) adding to the nociceptive load and to recognize any related neural, vascular, and/or lymphatic elements that might complicate underlying pathophysiologic conditions. The palpatory characteristics sought include sensitivity to measured palpation, tissue texture change, asymmetry, and restricted motion (STAR characteristics). Tissue texture changes often provide the most important information concerning the underlying pathophysiologic status of the periphery and the patient's homeostatic response status. 

Osteopathic manipulative treatment may be delivered to reduce or remove the identified somatic dysfunction or to attempt to modulate central and peripheral mechanisms involved in pain generation after weighing risk-to-benefit ratios associated with the resultant tentative diagnosis. Currently, palpated peripheral tissue texture characteristics have the greatest influence on the physician's choice of an activating force for the OMT. Sophistication should improve, however, as studies reveal how differing manual forces affect mechanoreceptors and mechanonociceptors in the tensegrity-integrin model, spinal cord gating mechanisms, and synaptic plasticity.¹⁶ 

The role for manual modes of therapy such as OMT has been documented for acute, subacute, and chronic LBP^18-21; in patients with LBP; specifically, spinal manipulation has effects similar to efficacious prescription NSAIDs and better effects than either physical therapy or home back exercises (or both).²¹ Positive long-term functional outcomes have also been demonstrated.²² Based on the literature, Mein²³ postulates that populations with subacute (secondary) and chronic (tertiary) LBP would benefit most from manipulative care rather than using more costly functional restoration, behavioral modification, and chronic pain management programs. 

Using a structure-function approach, Greenman²⁴ examined 183 patients who had persistent LBP for an average of 31 months. With osteopathic palpation, he identified three or more of six common diagnoses in 50% of this cohort (Table). Treatment with OMT to eliminate the identified somatic dysfunction resulted in nearly 75% of the dysfunctional group returning to work or to their activities of daily living. This author has also noted that undiagnosed somatic dysfunction, particularly “nonphysiologic dysfunctions” (such as pelvic shears), may result in years of persistent pain, either locally, or at distant sites linked through compensatory mechanisms or the development of MTrPs.^{25(pp463-512)} Dysfunction of one sacroiliac joint due to nonphysiologic pelvic shears greatly increases functional demand on the other sacroiliac joint and its stabilizing ligament. 

Removal of myofascial somatic dysfunction, including MTrPs, has also been shown to be extremely effective in reducing or eliminating persistent LBP. Patients with trigger points displayed on the common composite MTrP charts shown in Figure 3 responded well to a wide range of treatment modalities, including various OMT techniques such as counterstrain, post–isometric relaxation muscle energy, and myofascial release variants.^11,12 Manual correction of myofascial or articular somatic dysfunction also proves to be an effective adjunct regardless of whether pain also radiates into the lower extremity.^{12(pp168-185),26} 

With recurrence of the same pattern of pain and somatic dysfunction after otherwise effective OMT, the clinician should consider dysfunctional homeostatic mechanisms and a range of perpetuating factors (including postural decompensation), as well as site-specific primary viscerosomatic reflexes (Figure 1). 

Similarly, headache and neck pain have been extensively studied with respect to various somatic dysfunctions and manual approaches.^21,27,28 For example, placebo-controlled, diagnostic investigations have documented the importance of cervical pain from dysfunction of the zygapophyseal joints in patients with chronic neck pain and headache after whiplash injury.²⁹ 

Inattention to ergonomics at work or play increases functional demand that can perpetuate chronic or recurrent pain. Thus, osteopathic physicians should review patients' occupational and personal biomechanical stressors as part of the history. By providing patient education, they can address persistent pain that derives from prolonged periods of activities such as holding a phone between the ear and shoulder, using a keyboard with improper seating relative to desk height, or falling asleep slumped forward in a recliner. 

Effective pain management strategies aimed at treatment of peripheral pain generators will fail outright or secondary to recurrence of the original problem in the presence of excessive functional demand or other perpetuating factors. Unfortunately, prior failure may eliminate such strategies from their rightful place in the total treatment approach early on or cause the patient or the physician to dismiss them later in the program when the complicating postural stress or adjacent dysfunctions have been addressed. 

Timing, tissue response, and multifactorial conditions within the body unit affect OMM treatment strategies prompted by applying the structure-function principle. These conditions can both affect and be affected by other portions of the proposed algorithm (Figure 1). Physical examination of patients with persistent pain must go beyond identification of peripheral pain generators (especially from among the most commonly overlooked somatic sources) and screening for other perpetuating causes of pain: A properly constructed OMM approach cannot focus on one principle alone. 

While acute pain provides essential information for survival, persistent pain often results in anxiety, depression, and a reduction in the quality of life. Such body unity (or mind-body-spirit) effects of persistent pain are frequently uncovered with careful, yet traditional, history and physical examination skills supplemented by palpation. Such findings provide diagnostic clues as well as targets of opportunity to reduce precipitating, perpetuating, and magnifying factors associated with persistent pain. 

Discovery of a body unity dysfunction often shifts the traditional focus from simply identifying and removing an underlying organic disease (pain generator) to consideration of adding strategies designed to empower patients with chronic pain to reduce disability through modification of environmental and cognitive processes. Well-established behavioral interventions, including patient education, are commonly used in body unity approaches to chronic disabling pain conditions. 

An osteopathic palpatory examination will also aid physicians in eliciting a complete chronic pain history by gaining the patient's trust.² An integrated history is essential in determining the impact of pain on physical, mental, emotional, and spiritual functions unique to the individual. Understanding physical limitations, the most obvious manifestations of persistent pain, is part of a standard osteopathic medical education. Nonphysical limitations in the mental and emotional realms, however, are less often articulated by patients and require greater recognition by physicians. 

Osteopathic medicine's consideration of mind-body connections in persistent pain largely parallels biopsychosocial models embraced by multidisciplinary pain clinics. In such models, chronic pain is a frequent, well-established cause of depression³² with impact on both central and autonomic nervous systems. Furthermore, it is empirically recognized that physical pain may be temporally linked to anger, fear, or loss.^33,34 An example of this link is a patient's pain traumatically introduced during an accident in which there was time to hopelessly anticipate the other car's approach. Both fascial dysfunction and emotions associated with the injury serve to anchor such pain in these patients. Such persons may require additional counseling for the subsequently expressed nonphysical factors. 

Conversely, hands-on management of somatic dysfunction offers a unique and often effective access to these body-mind connections. Effects of OMT are occasionally dramatic, as in the catharsis effect of certain somatoemotional releases. Treatment of somatic dysfunction often offers an opportunity to open discussion and seek coping strategies to reduce patients' mental, spiritual, and emotional pain. 

Various homeostatic coping and regulating mechanisms influence physiologic processes responsible for maintaining pain.^35-37 Homeostasis may be altered through focused psychosympathetic, biochemical, or neuroendocrine mechanisms affecting specific structures or target receptors, or both. Conversely, an integrated series of homeostatic mechanisms may provide for panstructural biomechanical changes such as shifting weight-bearing responsibilities away from painful sites. The process creates easily recognizable patterns associated with certain pain syndromes. 

Because OMT has long been noted to have an independent positive effect on certain autonomic, respiratory, circulatory, postural, and neuroendocrine mechanisms, it is rational to consider that influencing these mechanisms may positively impact pain modulation, as well (Figure 4). 

SMP/SIP taxonomy dissociates the presence of pain from gross signs of sympathetic dysregulation (eg, altered temperature, excessive sweating, trophic changes), so that such obvious evidence of abnormal sympathetic activity need not accompany SMP. Thus, while SMP syndromes such as causalgia and reflex sympathetic dystrophy are often relieved by sympathetic ganglion blocks,⁴⁰ persistent pain with lesser SMP may be addressed with OMT techniques designed to treat somatic dysfunction and modulate hypersympathetic activity.⁴¹ 

Modulation of hypersympathictonia has been linked to pain reduction, enhanced healing rates, and improvement in a variety of visceral and somatic functions. It is considered to be a hall-mark effect of the OMM approach and warrants consideration in chronic pain conditions. 

The treatment goals associated with the Zink respiratory-circulatory model are traditionally administered in the following sequence. 

The act of deep breathing creates obvious motion in 136 joints and is palpable into all body tissues. It is a continuous motion with active and passive components. Through tensegrity relationships, the patient or physician can focus deep breathing to remove motion restrictions or engage neuromuscular reflexes to achieve tightening or relaxation of selected tissues.⁴⁴ 

Pain associated with postural stress and strain can be sclerotomal (postural ligaments) or myotomal (postural muscles). It can also have a significant role in radiculopathies associated with osteoarthritic and discogenic conditions.⁴⁵ Irvin⁴⁶ demonstrated that chronic complaints throughout the body could be attributed to an unlevel sacral base and that reestablishing postural homeostasis removed most of these symptoms. 

The OMM approach to postural care is described thoroughly in Foundations for Osteopathic Medicine and consists of patient education, OMT, exercise, and sometimes an appropriate orthotic regimen.^{14(pp603-632)} The Zink respiratory-circulatory approach⁴² described earlier is also applicable in preparing the tissues for postural homeostasis because of the body unit's tendency to compensate for postural imbalance at the regional transition zones. 

Persistent nonmalignant pain is not a single entity. It has many different causes and manifestations, each with varied characteristics and names. Osteopathic manipulative medicine employs a history and physical examination designed to reveal any previously unidentified pain generator or underlying cause for persistence of pain. In addition, OMM screens for signs of depression or other significant nonphysical links contributing to pain. Based on the OMM examination, physicians can develop an individualized osteopathic prescription to address these findings with the goal of decreasing pain and empowering patients to reduce its impact on their quality of life. 

In addition to appropriate strategies to manage the symptom of pain, the OMM algorithm incorporates osteopathic principles to identify and address a variety of host factors directed toward the underlying cause and the tangible impact of persistent pain on the patient. These principles provide a framework for patient education to foster compliance built on understanding complex interrelationships. 

Each osteopathic prescription seeks to discover and incorporate the factors needed to address the individual's unique response to his or her pain. The emphasis in treating patients with persistent nonmalignant pain should be on improving function, decreasing peripheral nociception and central facilitation, and empowering the patient to move forward in resuming their activities of daily living. 

Applying osteopathic principles as part of an effective treatment strategy for patients with chronic pain results in an individualized care plan combining nondrug treatment strategies with pharmacotherapy. Patient education included in the comprehensive plan helps to improve quality of life and break the vicious cycle seen in the pathophysiology of persistent pain.