Volume 28, Issue 7 , Pages 547.e1-547.e9, September 2005
Reflections on the “type O” disorder
Article Outline
- Scope of Practice
- The Somatovisceral Reflex
- Type M vs Type O Management
- Chronic Spinal Pain
- Yellow Flags as the Supraspinal Influences in Chronic Pain?
- Treatment of the Type O Condition
- Does Medicine Consider the Yellow Flags in Type O Conditions?
- Where to from Here?
- References
- Copyright
In 1979, the Royal Commission into Chiropractic in New Zealand popularized a description of musculoskeletal and nonmusculoskeletal injuries presenting to chiropractors. The terms referred to the treatment of “type M” (musculoskeletal) conditions and visceral “type O” (organic) conditions. Although chiropractors are considered to appropriately treat the type M condition, treatment of the type O condition is not considered as appropriate by many inside and outside the profession. Chiropractors usually cite research into the somatovisceral reflex as a mechanism to support their position. Although this research is of high quality, it is lacking in its direct application to chiropractic management strategies.
Chiropractors have been treating visceral conditions since the inception of their profession. This treatment has been diverse in nature, and some have claimed to be treating all manner of visceral dysfunction and disease. Despite the chiropractic profession being approximately 110 years old, very little research into the effect of chiropractic manual therapy has been conducted in this subgroup of the population of patients who the chiropractor treats. In addition, psychosocial issues have been recognized as important to the work of chiropractors for some time1; however, their potential role in the generation of type O disorders has not been so recognized. Although there have been a few attempts at investigating treatment of visceral conditions, much of the data are flawed by limited or poor methodology, and many of the conclusions are weak, irrelevant, or negative in nature (Table 1).2, 3, 4, 5, 6, 7, 8 Despite this, some small-power studies have shown positive outcomes for such management (Table 2).9, 10, 11, 12, 13, 14, 15, 16 Despite these findings, strong claims are made as to the success of manual therapy on visceral function. Many of the claims cite a mechanism that involves the somatovisceral reflex. This article discusses the relevance of the somatovisceral reflex as the main mechanism in the proposed effect by manual therapy on the type O condition and its relevance to potential management and research.
Table 1. Studies citing a negative effect on Chiropractic spinal manipulative therapy on visceral function2, 3, 4, 5, 6, 7, 8
| Author(s) | Result of study |
|---|---|
| Leboeuf et al2 | No effect on nocturnal enuresis |
| Brennan et al3 | No change in lymphocyte profile |
| Reed et al4 | No change in bed wetting |
| Nielsen et al5 | Objective changes nil |
| Subjective changes (patient-rated asthma severity) decreased by 34% | |
| Olafsdottir et al6 | Chiropractic SMT no more effective than placebo in treatment of infantile colic |
| Straub et al7 | Chiropractic SMT does not reduce effects of jet lag |
| Goertz et al8 | For patients with high-normal blood pressure or stage I hypertension, chiropractic SMT + dietary modification program no different to diet alone |
Table 2. Studies citing a positive effect on chiropractic spinal manipulative therapy on visceral function9, 10, 11, 12, 13, 14, 15, 16
| Author(s) | Result of study |
|---|---|
| Vernon et al9 | Small increase in serumβ-endorphin levels at the 5-min postintervention |
| Yates et al10 | Improves systolic and diastolic blood pressure, and reduces state anxiety |
| Kokjohn et al11 | Chiro SMT may be effective for 1° dysmenorrheal |
| Brennan et al12 | Enhanced phagocytic cell respiratory burst by SMT |
| Peterson13 | Decreased the intensity of emotional arousal reported by phobic subjects. |
| Wiberg et al14 | Is effective in relieving infantile colic |
| Walsh & Polus15 | Symptoms associated with premenstrual syndrome generally reduced by Chiro STM & soft tissue therapy |
| Tuchin et al16 | Migraine 90% better in 22% of patients |
Scope of Practice
Chiropractors primarily treat patients with neuromusculoskeletal conditions.17, 18 It is not surprising that their training is focused toward such management.19 However, Hawk et al17 have estimated that approximately 10% of conditions presenting to American chiropractors are of a nonmusculoskeletal nature. European data suggest a similar figure of 10% or less,20 although some jurisdictions are reported to see considerably less (less than 2% in the Netherlands).21 Interestingly, those practices with the highest proportion of nonmusculoskeletal patients in the United States were more likely to be in populations of greater than 100
000; these physicians used common chiropractic spinal manipulative therapy less often than other practitioners and used more nonadjustive techniques (including diet/nutrition counseling, nutritional supplementation, herbal preparations, naturopathy, and homeopathy).17
Although a diversity of treatment options and conditions is important to primary contact practitioners, so is the training to manage the diversity of conditions that is likely to be encountered with such primary contact status. It appears that as long as chiropractors stay within the realm of the type M musculoskeletal presentations, they may be less likely to fall foul of criticism leveled by the medical fraternity22 and others within and outside the chiropractic profession.18 However, strong criticism usually follows those practitioners who choose to manage nonmusculoskeletal conditions. Much of this criticism is centered on the appropriateness of the care that is delivered, as well as the ability of the chiropractor to diagnose the conditions that are potentially being treated.22 Given the nature of most chiropractic education around the globe, some college curricula would be more deserving of this criticism than others.
In contrast, the treatment of the type O condition is often seen by chiropractors to be (1) part of their scope of practice, (2) a right of practice for a primary contact practitioner, and (3) consistent with the foundation principles of chiropractic and the philosophy on which it is based. Interestingly, this approach is collectively applauded and embraced by many in the profession. Therein lies the dilemma for those entering the debate on the treatment of the type O disorder.
In an attempt to justify the treatment of these conditions and numerous anecdotal reports of success with some of these conditions, chiropractors have sought to explain the mechanism of what they are doing by using well-established neurophysiologic explanations. The somatovisceral reflex is at the core of this explanation.
The Somatovisceral Reflex
The somatovisceral or somatoautonomic reflex is thought to result from the stimulation of somatic structures (skin, muscle, ligament, bone, etc) to cause a reflex change in the efferent output to a visceral or effector organ.23, 24, 25, 26 These spinal reflexes span the visceral organs and have been investigated by many researchers including Sato27 and others.28, 29, 30, 31 Although this work is of good quality, it is not the validation that is often portrayed by many in the chiropractic profession.
These reflexes are short-term in nature.32, 33 The studies on which they are based have largely been conducted using an animal model and have occurred in normal physiological states or after spinal transaction.34, 35, 36 Very little work has been conducted in a pathological state of visceral function that would equate to a disease state; as well, not as much work has investigated the longer-term nature of the reflexes in normal or pathological tissue.
Even less research has focused on the effect of treatment on the reflexes or their longer-term sequelae in normal or pathological states. In addition, those investigating the somatoautonomic reflexes point to the important role that supraspinal influences have on somatic and visceral structures of the body.30, 37, 38, 39, 40 These supraspinal centers refer to the combined action of higher brain centers such as the thalamus, reticular formation, cerebellum, cortex, hypothalamus, and limbic system.
Thus, this may be another potential explanation for the anecdotal success of type O treatments reported by so many chiropractors. This explanation is not normally discussed as being a factor in the etiology or treatment of the type O condition.
Type M vs Type O Management
Chiropractors primarily treat type M or neuromusculoskeletal conditions.19 They are said to show equal skill in managing these conditions as medical practitioners.22 It is also reported that chiropractors deal with chronic spinal pain syndromes and that their case mix of spinal pain and associated mental health is, on average, often more severe than their medical counterparts.18
In addition to case mix ratio of the type O to type M conditions, chiropractors treat a great deal of chronic spinal musculoskeletal pain18, 22; however, chronic pain is associated with emotional or psychological content.41, 42
Chronic Spinal Pain
Chronic pain has attracted much interest in recent years because of the cost of its collective management and the association that it shares with the advent and promotion of evidence-based practice.43, 44 Many studies have investigated outcomes associated with chronic pain presentations (Table 3).45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71 Table 4 highlights that assessment and treatment of type M conditions usually associated with manual therapy are not predictive of long-term outcomes.72, 73, 74, 75, 76, 77, 78, 79, 80, 81
Table 3. Studies that have shown positive outcomes for the treatment of chronic spinal pain45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71
| Authors | Intervention |
|---|---|
| Giles & Muller45, Andersson et al46, Blomberg et al47 | Manipulation |
| Hagen et al48 | Mobilization |
| Mannion et al49 | Aerobic exercise |
| Descarreaux et al50, Rittweger et al51 | Exercise |
| Mullican & Lacy52 | Medication |
| Hurwitz et al53, Sherry et al54 | Electrotherapy |
| Leibing et al55, Molsberger et al56 | Acupuncture |
| Rozenberg et al57 | Rest |
| Holm58 | Surgery |
| Chrubasik et al59 | Nutrition |
| Geurts et al60 | Radiofrequency denervation |
| Stam et al61 | Homeopathy |
| Constant et al62 | Spa therapy |
| Ruoff et al63 | Analgesics |
| Kumar et al64, Vlaeyen et al65, Kovacs et al66 | Other approaches |
| Cherkin et al67, Cherkin et al68, Burton et al69, Roberts et al70, Linton & Andersson71 | Printed material changing behavior. The printed material is more effective if accompanied by verbal illustration and support and actual physical performance. |
Table 4. Factors that do not predict chronic pain outcomes72, 73, 74, 75, 76, 77, 78, 79, 80, 81
| Authors | Factors |
|---|---|
| Valat et al72 | Weight & height |
| Hildebrandt et al73 | Physical variables (ie, mobility, strength, endurance, and physical performance) showed limited predictive value |
| Matsui et al74 | Light-moderate physical workloads |
| Haas et al75 | Early post treatment success |
| Toomingas et al76 | Signs of tenderness in the joints, tendons, or muscular insertions or signs in nerve compression tests |
| Bigos et al77 | Physical and injury factors |
| Bigos et al78 | Pre-employment screening (individual physical factors) |
| Hicks et al79 | Segmental mobility |
| Natvig et al80 | Specific low back pain in workers |
| Truchon & Fillion81 | Age, sex, ethnicity, education, and work task probably not predictors |
Although spinal manipulative therapy has shown beneficial outcomes in chronic spinal pain, other forms of therapy have also shown positive outcomes (Table 3). However, no one approach has shown mastery over chronic spinal pain.81
Other studies have determined that the only predictors of chronicity in randomized controlled trials are the yellow flag presentations (Table 5).82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 Psychosocial variables associated with pain are commonly referred to as yellow flags.95 These yellow flags include several variables related to attitudes and beliefs about pain and behavior associated with pain. They include issues of compensation, diagnosis, treatment factors, analysis, family, and work.95 Despite that the yellow flags are usually used in isolation, red flag and yellow flag conditions are not mutually exclusive.95 Red flag conditions are those that may alert the practitioner to serious and potentially uncommon conditions that require urgent medical management.97
Table 5. Yellow flag factor in chronic pain82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96
| Author | Yellow flag factor |
|---|---|
| George et al82, van den Hout et al83 | Fear avoidance behavior |
| Kole-Snidjers et al84 | Operant-behavioral factors important |
| Bigos et al78 | High job dissatisfaction |
| Krause et al85 | High perceived exertion at work |
| Elders & Burdorf86 | Malaise |
| Fordyce et al87 | Monotonous tasks, unsatisfactory social contacts outside work |
| Thorbjornsson et al88 | Unemployment & compensation |
| Sanderson et al89 | Demands |
| Linton90 | Locus of control |
| Krause et al91 | Belief that work is dangerous catastrophic thoughts |
| Severeijns et al92 | Low workplace social support |
| Hoogendoorn et al93 | Low job satisfaction job content and job control |
| Hagen et al94 | Feeling of being worn out |
| Krause et al91 | Coworker support |
| Krause et al85 | Low supervisory support at work |
| Linton90 | Stress |
| Linton90 | Work pace |
| Linton90 | Emotional effort at work |
| Kerr et al95 | Physically demanding job poor workplace social environment |
| Kerr et al95 | Inconsistency between job education level |
| Kerr et al95 | Better job satisfaction |
| Kerr et al95 | Low job control (borderline association) |
| Valat et al72 | Compensation for a spinal condition, receipt of work-related sickness payments, or litigation |
| Hagen et al94 | Poor general health |
Yellow flags have been recognized as being important in the chiropractic treatment of low back pain.1 The usual clinical factors are poor or weak predictors of progression of acute pain to a chronic state.97 Chronic progression is generally predicted by yellow flags, and it is highly likely that the yellow flags are etiologic in the progression from acute to chronic pain.98, 99, 100
To date, there has been only one set of yellow flag clinical observations that has been operationally defined.101 The Waddell nonorganic signs (Fig 1) have shown the ability to predict chronicity when a high score on the 7-inventory test is measured.102 The performance of this inventory entails a series of physical examinations that are not expected to aggravate pain. Despite that the authors believe a high score is reflecting fear and or anxiety on the part of the subject,96 many clinicians have incorrectly interpreted this to be indicative of a malingerer.102

Fig 1.
Waddell's physical signs: predictors of chronicity. 101
Yellow Flags as the Supraspinal Influences in Chronic Pain?
From a treatment perspective, outcomes in chronic pain have been shown to be improved by analgesics, exercise, and cognitive/behavioral therapies.96 Colloquially, this translates to patient advice that reads, “Move the injured area, keep a positive mental attitude and if it's sore, use a pain killer.”
Despite that some chiropractors would consider such advice unsavory, there is strong efficacy to such advice.96 This is true compared with the more customary intervention of chiropractors of manual or electrotherapy options. These interventions have been shown to have mixed evidence as to their efficacy.103, 104, 105, 106, 107, 108 These interventions have been associated with positive or no effective outcome in controlled studies.103
This finding is as important as it is surprising for manual therapists. It signals a clear association between cognitive processes and chronic pain. Moreover, it could be argued that as chiropractors treat the chronic pain syndromes successfully,104 they are also influencing the supraspinal centers as well. This mind-body association leans more toward a vitalistic approach to health care than it does the more common mechanistic approach.
Thus, a potential cause-and-effect mechanism could be proposed for the action of manipulation on the supraspinal centers. This mechanism involves not just local spinal reflexes or reflexes that are primarily mechanonociceptor-based but other supraspinal or psychological reflexes. In addition to the potential supraspinal influence on type M disorders, research has also shown that many type O disorders have a distinct supraspinal component (Table 6).108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 Furthermore, there is evidence that a reduction of this supraspinal effect may be beneficial to the patient outcome.102, 122, 123
Table 6. Some visceral conditions that medicine is recognizing to be strongly associated with supraspinal influences108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121
| Author(s) | Condition |
|---|---|
| Richter & Bradley109 | Gastroesophageal reflux disease |
| Sternberg et al110 | Chronic functional abdominal pain |
| Rogers et al111 | |
| Kellow & Phillips112 | |
| Whitehead et al113 | |
| Drossman et al114 | Crohn's disease |
| Carney et al115 | Coronary artery disease |
| Carney et al116 | |
| Camara & Danao117 | Psychoneuroimmunology |
| Ader & Cohen118 | SLE |
| Kiecolt-Glaser & Glaser119 | |
| Blumenthal et al120 | Coronary-prone behavior and hostility |
| Rosenman et al121 |
Treatment of the Type O Condition
Despite anecdotal claims of success with type O conditions, success in management is not guaranteed nor is it predictable. Treatment is at best a trial of therapy rather than a known quantity. Unfortunately, some practitioners are overzealous in their expectation of outcome, and this expectation is conveyed to the patient. Although such a positive expectation can be associated with its own positive outcomes,124 it is irresponsible to claim a certainty in outcome when none has been established.
Aside from the elucidation of the mechanistic action of the treatment effects of the chiropractic model of type O treatment, the ability of the chiropractor to diagnose specific conditions and, potentially, to refer patients for more appropriate management continues to be a thorn in the side of the profession.22 I propose that it is for these reasons that chiropractic treatment of the type O condition is often questioned.
Does Medicine Consider the Yellow Flags in Type O Conditions?
Medicine has traditionally operated in the biomedical model. This model focuses on a tissue in lesion and is both mechanistic and pathological in orientation. This model easily explains the “red flags,” but does not explain the influence of the “yellow flag” psychosocial influences on pain. In the biomedical model, all disease is described for derangement of underlying physiochemical mechanisms. It is reductionist and exclusive and leaves no room for social, psychological, or behavioral dimensions of illness.125 The biomedical model has been rejected by some in the last 20 years in favor of a biopsychosocial model.126
The biopsychosocial model is defined as127 “a framework for understanding the integration and interplay of the biologic, psychological, and social dimensions of health, disease, and health care.”
The effective integration of the biopsychosocial model requires 3 component parts.128 These include (1) a stressful event or challenge to the system, for example, an exposure to an infectious agent, loss of a family member, or problems at work; (2) a physiologic vulnerability, for example, a predisposition to bronchial spasm; and (3) a compromise of one or more pathophysiologic systems: immune, nervous, cardiovascular, and others.
It would appear that allopathic medicine is slowly adapting to the biopsychosocial model and that a whole new area of research referred to as neuropsychoimmunology has developed to investigate the model.129 To illustrate this adaptation, Katon et al130 found that patients with chest pain and normal coronary arteriograms had a higher level of anxiety, depression, and panic disorder than those with normal psychosocial characteristics and arteriographic studies that showed coronary stenosis.
Thus, supraspinal influences seem to be operating on visceral structures too. Medicine is recognizing these factors and beginning to act on them to improve patient outcomes. Despite that chiropractors may be aware of the psychosocial aspects of chronic musculoskeletal pain, do they collectively consider similar influences on the visceral structures? Moreover, do they consider the supraspinal influences on both type O and type M conditions to be important in the generation and treatment of these conditions?
Thus, it would be important for the chiropractic profession to consider this potential mechanism for the cause and treatment of not only the type M conditions, but also the type O conditions. This consideration should be undertaken as there appears to be compelling evidence (albeit indirect) that psychovisceral reflexes may be operating at least as much and probably more than the much-vaunted somatovisceral reflex. Chiropractors should consider embracing the role of the supraspinal factors in the etiology and treatment of their patients.
Where to from Here?
Chiropractors should embrace evidence-based research into the type O condition or face becoming increasingly marginalized by those inside and outside our profession. Much work has already begun into the somatovisceral reflex. Work by Sato,27, 28 Budgell,28, 29 and Bolton30, 31 is being followed by other research groups, including groups from Japan and Australia. However, much of this research appears to focus on the spinal aspects of the somatovisceral reflex with the supraspinal aspects largely ignored. It is timely for chiropractors to embrace the research on the supraspinal influences in the type O condition, both within the laboratory (animal based) and in the clinic (human clinical trials).
In addition to the current research base, existing and newer therapies should be investigated to determine if they help address the supraspinal component of these conditions. Finally, this research should be applied to both type M and type O conditions to investigate the role that supraspinal influences have on the expression and treatment of these conditions.
Chiropractic is at a crossroad in its development in many ways. With regard to the type O disorder rather than the profession developing an almost dualistic support for the type O/type M vitalistic/mechanistic approaches to management, there exists an acceptable model to act as a bridge between the collective treatment impasse. The embrace of the supraspinal influences inherent in the biopsychosocial model may serve us well when investigating the enigma that is evidence-based practice.
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PII: S0161-4754(05)00192-2
doi:10.1016/j.jmpt.2005.07.014
© 2005 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.
Volume 28, Issue 7 , Pages 547.e1-547.e9, September 2005
