One of the reasons I chose the acupuncture course I am currently taking is that the instructors are very clear about rejecting the Traditional Chinese Medicine mythology of Qi, Yin and Yang, and all the rest that is often used to justify or explain the potential benefits of needling. The course purports to take a purely scientific approach to understanding and using acupuncture. As I have discussed previously, however, a fair bit of traditional acupuncture practice is accepted as effective based on anecdotal experience and then rationalized post hoc with sometimes questionable anatomic or neurophysiologic explanations. One of the most intensively used of these is the myofascial trigger point concept (MTrP).
Myofascial trigger points are supposed to be focal areas of tension or contraction in muscles which are irritable and contribute to chronic refractory pain. The argument is that these develop in response to local injury, to certain postural or activity patterns, or even to diseases in internal organs or the nervous system. Practitioners who treat such trigger points claim to be able to detect them as knots or taut bands within muscles. Such trigger points are treated primarily by “releasing” them via some kind of stimulus, such as needling, electrical stimulation, massage, laser therapy, and so on.
The concept of the MTrP is more widely accepted in the conventional medical community than acupuncture more generally, though it is primarily utilized by osteopathic physicians, chiropractors, and others who focus on physical manipulative therapies, such as massage therapists, physical therapists, etc. However, the validity of the concept and the effect of needling and other rMTrp releasing therapies is often assumed as proven in this course and then used as a explanation for some of the proposed effects of acupuncture. This is not surprising since the course director, Dr. Robinson, is an osteopath as well as a veterinarian.
There certainly is some research evidence to support the concept of MRtP and the effect of needling as a treatment. But then there is also research evidence that appears to support acupuncture, and as we have seen when looking at it carefully and critically, it doesn’t necessarily mean what advocates claim it means. (1, 2) There is clearly controversy about the MTrP concept and the effects of therapies focused on myofascial release, and it is worth bearing this in mind rather than simply accepting the idea as true and using it to then justify some claims for acupuncture.
The most recent narrative review challenging this concept was published last year, and the authors make a quite definitive claim about it:
Quintner JL, Bove GM, Cohen ML. A critical evaluation of the trigger point phenomenon. Rheumatology (Oxford). 2015 Mar;54(3):392-9.
We have critically examined the evidence for the existence of myofascial TrPs as putative pathological entities and for the vicious cycles that are said to maintain them. We find that both are inventions that have no scientific basis, whether from experimental approaches that interrogate the suspect tissue or empirical approaches that assess the outcome of treatments predicated on presumed pathology. Therefore, the theory of MPS caused by TrPs has been refuted.
Their claim rests on several grounds. The first is the problem with consistent identification of trigger points. Several studies involving experts who treat MTrP look at inter-observer reliability. These experts were asked to examine the same patients and give independent assessments of where trigger points were found. In these studies, the practitioners claimed to locate trigger points in different places and did not agree with each other to any significant extent unless they were first told what the underlying diagnosis was. This suggests that without knowing what is wrong with the patient in advance, even experts cannot reliably detect trigger points on physical exam and that they are inclined to base their subjective identification of such points primarily on what they expect to find when they already know the diagnosis, rather than on what they actually feel when doing a physical exam.
This is a pretty serious problem given that physical examination is supposed to be the main way trigger points are found. It is the same kind of problem that helped demonstrate that the Vertebral Subluxation touted by chiropractors as a major cause of illness was actually imaginary. If such inability to detect trigger points turns out to be a consistent finding, it would strongly suggest that such points don’t exist as objective entities which can be detected by physical examination, which would greatly undermine the idea that they exist at all or are a major source of clinical symptoms.
The authors also review other ways of identifying and characterizing trigger points, including biopsy findings, electromyography, and others, and they conclude that the evidence is mixed and unclear as to whether there is a single, common lesion that can be found on physical exam and associated with clinical disease.
This review also examines the evidence that needling to release trigger points is clinically effective. A number of systematic reviews and clinical trials have been done on this question, and the over conclusions are: the quality of the research evidence is mixed and often too low to be reliable; many other therapies are usually used along with trigger point needling, so it is difficult to determine which, if any, might be responsible for improvement; trigger points are identified in many very different patients with very different underlying diseases, so variation in how these patients do is high and complicates comparison of studies looking at needling for trigger point release.
Other critics of MTrP theory have made similar criticisms, including some physical medicine practitioners who have shifted from automatic acceptance of the concept to skepticism. I haven’t invested the time in examining the evidence as closely as I have looked at that concerning acupuncture, so I don’t have a strong opinion, but I do have some skepticism about the concept.
In particular, I am concerned by the inherent subjectivity in detection of trigger points and assessment of patient response to therapy. In demonstrating the location and treatment of trigger points, Dr. Robinson rests a lot of weight on interpretation of patient behaviors that could reasonably be interpreted differently. As not only a vet who has practiced for many years but someone with training in animal behavior, I know how easy it is to project our own expectations onto the behavior of other animals. If I expect to find pain in a certain spot and initially don’t, it is easy to press just a little harder until I get the reaction I expect, often without even realizing I am doing so. The lack of an objective, verifiable way of detecting trigger points and their resolution with needling is, then, a significant problem for this concept in veterinary medicine.
Given the lack of clarity on MTrP theory, it is not very helpful to use this concept as an explanation or guide for acupuncture. It simply shifts the ground from one muddy and poorly demonstrated set of ideas to another. There is no doubt, of course, that people often feel better when given various kinds of manual treatments. I suspect the same is true of many companion animals who have, after all, been intensively selected for generations to accept or even desire human contact. However, we must be cautious in projecting our expectations, beliefs, and theories onto our animal patients without robust objective evidence, since we run the risk of being fooled by the caregiver placebo effect and other phenomena that can leave us believing we have helped them when in reality we have not.
Here are a few of the studies discussed in the Quintner review:
Inter-observer reliability in MTrP detection:
Hsieh CY, Hong CZ, Adams AH et al. Interexaminer reliability of the palpation of trigger points in the trunk and lower limb muscles. Arch Phys Med Rehabil 2000;81: 258_64.
Lew PC, Lewis J, Story I. Inter-therapist reliability in locating latent myofascial trigger points using palpation. Man Ther 1997;2:87_90.
Myburgh C, Larsen AH, Hartvigsen J. A systematic, critical review of manual palpation for identifying myofascial trigger points: evidence and clinical significance. Arch Phys Med Rehabil 2008;89:1169_76.
Wolfe F, Simons DG, Fricton J et al. The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease. J Rheumatol 1992;19:944_51.
Clinical effect of needling trigger points:
Annaswamy TM, De Luigi AJ, O’Neill BJ et al. Emerging concepts in the treatment of myofascial pain: a review of medications, modalities, and needle-based interventions.PM R 2011;3:940_61.
Cummings TM, White AR. Needling therapies in the management of myofascial trigger point pain: a systematic review. Arch Phys Med Rehabil 2001;82:986_92.
Ho KY, Tan KH. Botulinum toxin A for myofascial trigger point injection: a qualitative systematic review. Eur J Pain 2007;11:519_27.
Rickards LD. The effectiveness of non-invasive treatments for active myofascial trigger point pain: a systematic review of the literature. Int J Osteopathic Med 2006;9: 120_36.
Tough EA, White AR, Cummings TM et al. Acupuncture and dry needling in the management of myofascial trigger point pain: a systematic review and metaanalysis of randomised controlled trials. Eur J Pain 2009; 13:3_10.