Myofascial Pain Syndrome/MPS/Myofascial Syndrome
- 1 Definitions
- 2 Common symptoms
- 3 Trigger points
- 4 Simon’s criteria
- 5 Acute and chronic forms
- 6 Regional or generalized
- 7 Prognosis
- 8 Primary and secondary types
- 9 Prevalence in the US
- 10 Prevalence of MPS in chronic back pain
- 11 Contributing factors to MPS
- 12 Relation to fibromyalgia
- 13 Co-occurrence with back pain
- 14 rTMS treatment of myofascial pain syndrome
- 15 For additional information about MPS
This is a persistent chronic regional muscular pain disorder involving pressure sensitive areas of the body called trigger points which when pressed cause referred pain that is somewhat removed from the location where the pressure was applied. These referred pains involve predictable spatial pain patterns. The patterns have been studied in depth and atlases exist to show the clinician the expected locations of pain radiation for numerous tender points that have been discovered.
The condition is common after repetitive muscle contractions such as those occurring at work or during hobbies. It also appears to be related to muscle tension.
Travell et al. definition
“The sensory, motor, and autonomic symptoms caused by myofascial trigger points. (Myofascial Pain and Dysfunction, Travell JG and Simons D. Part 1, Chapter 1, Glossary, pages 1-7, see page 5, and visible in full online at: https://books.google.ca/books?id=sU0XupX7DGsC&dq=%22Digital+examination+of+a+muscle+to+determine+the+absence%22&source=gbs_navlinks_s.) Travell was president Kennedy’s doctor. She coined the term “myofascial pain syndrome” in 1952. (The myofascial genesis of pain. Travell J, Rinzier S. Postgrad Med- 1952; 11: 425-34, partially visible online at: https://www.tandfonline.com/doi/abs/10.1080/00325481.1952.11694280.)
This is “a specific form of soft-tissue rheumatism that results from irritable foci (trigger points) within skeletal muscles and their ligamentous junctions.” (Myofascial pain syndromes and their evaluation, Robert Bennett. Best Practice & Research Clinical Rheumatology, June 2007 Volume 21, Issue 3, Pages 427–445The abstract is visible at: http://www.bprclinrheum.com/article/S1521-6942(07)00026-5/abstract and available in full online at: https://pdfs.semanticscholar.org/b4bb/bc56551ec51abc6f1b5095742e89a9d666a2.pdf.)
These include: deep muscle aches, persistent and progressive pain, tender knots in one’s muscles and loss of sleep due to pain.
Bennett states: “The clinical science of trigger points can be traced to the pioneering work of Kellgren in the 1930s, with his mapping of myotomal referral patterns of pain resulting from the injection of hypertonic saline into muscle and ligaments. Most muscles have characteristic myotomal patterns of referred pain; this feature forms the basis of the clinical recognition of myofascial trigger points in the form of a tender locus within a taut band of muscle which restricts the full range of motion and refers pain centrifugally when stimulated.” June 2007Volume 21, Issue 3, Pages 427–445 at: https://pdfs.semanticscholar.org/b4bb/bc56551ec51abc6f1b5095742e89a9d666a2.pdf
“Among criteria that are most frequently employed are those re-deﬁned by Simons et al. in 1999 [Simons DG, Travell JG, Simons LS. Upper half of body. In: Travell & Simons’ myofascial pain and dysfunction. The trigger point manual. 2nd ed., vol. 1. Baltimore: Williams & Wilkins; 1999. 1038. http://books.google.com.au/books?id=sU0XupX7DGsC&printsec=frontcover#v=onepage&q&f=false.], according to which an MPS can be diagnosed if ﬁve major criteria and at least one out of three minor criteria are satisﬁed. The major criteria include (a) localised spontaneous pain; (b) spontaneous pain or altered sensations in the expected referred area for a given TrP (target area); (c) a taut, palpable band in an accessible muscle; (d) exquisite, localised tenderness in a precise point along the taut band; and (e) a certain degree of reduced range of movement when measurable.” (Myofascial pain syndromes and their evaluation. Giamberardino MA1, Affaitati G, Fabrizio A, Costantini R. Best Pract Res Clin Rheumatol. 2011 Apr;25(2):185-98, available in full online at: https://www.researchgate.net/publication/51806532_Myofascial_pain_syndromes_and_their_evaluation.)
Acute and chronic forms
According to Gerwin, MPS can be acute or chronic.
Regional or generalized
According to Gerwin, it can be regional or generalized. Gerwin also states that when it becomes chronic it tends to generalize “but it does not change to fibromyalgia.” (Classification, Epidemiology, and Natural History of Myofascial Pain Syndrome. Robert D. Gerwin, MD Current Pain and Headache Reports 2001, 5:412–420 abstract available at: https://link.springer.com/article/10.1007/s11916-001-0052-8.)
According to Gerwin (2001), it is treatable and can respond to manual and injection techniques, but this “requires attention to postural, ergonomic, and structural factors, and toxic or metabolic factors that impair muscle function.”
Primary and secondary types
According to Gerwin (2001), secondary myofascial pain syndrome is they type that develops as a consequence of another condition.
Primary does not.
Prevalence in the US
A 2004 paper estimated there were 44 million cases in the US. (Myofascial pain disorders: theory to therapy. Wheeler AH. Drugs. 2004;64(1):45-62.)
[Comment: This number would come as a surprise to many health care professionals. If doctors are not aware that it is common, then they may not be aware enough to search for it, and this could easily lead to under-diagnosis.]
Prevalence of MPS in chronic back pain
A study by Chee Kean Chen et al. found that the prevalence of MPS among chronic back pain patients was 63.5%. Of these, secondary MPS made up 81.3% of the total MPS. They also found an association between female gender and the risk of developing MPS (χ2 = 5.38, P = 0.02, O.R. = 2.4). Myofascial Pain Syndrome in Chronic Back Pain Patients, Chee Kean Chen, MD and Abd Jalil Nizar, MD*Korean J Pain. 2011 Jun; 24(2): 100–104, doi: 10.3344/kjp.2011.24.2.100
Contributing factors to MPS
Myofascial Pain Syndrome: Uncovering the Root Causes, Justin A. Rodante, PA-C, MPH, Qasim A. Al Hassan, MB, BS and Zainab S. Almeer, MB, BS Practical Pain Management, Volume 12, Issue #6, https://www.practicalpainmanagement.com/pain/myofascial/myofascial-pain-syndrome-uncovering-root-causes
According to a review by Hassan et al., "contributing factors which are linked to the development of myofascial pain syndrome include:
- Trauma: joint or muscle, including whiplash, repetitive trauma or overuse injuries
- Postural imbalances
- Psychological stressors
- Sleep deprivation
- Chronic disease states: including vitamin deficiencies, endocrine disorders, chronic infections and fibromyalgia
- Orthopedic and arthritic conditions including osteoarthritis, spinal degenerative conditions, scoliosis, abnormal leg length
- Neurological including radiculopathy"
Relation to fibromyalgia
My present impression (as if 2017) is that this disorder is closely related to fibromyalgia and that it is a kind of localized fibromyalgia whereby the patient will present with pain focused on a particular body part such as arm. Based on unpublished physical examinations of approximately 100 fibromyalgia patients done by pressing on their 18 standard tender points with a Fischer algometer and stopping when they reach their pressure pain threshold, I found that there is a sub-group that has radiation of pain. My impression is that these tend to be the more severe cases of fibromyalgia. Traditionally, doctors considered a tender point to be an entity that did not involve radiation when pressed, and a trigger point is an entity that has radiation and which is associated with myofascial pain syndrome. My present impression is that the lines are blurry and the disorders overlap.)
Co-occurrence with back pain
A study of chronic back pain patients by Chen et al. found a surprising high prevalence of myofascial pain syndrome. (Chen CK, Nizar AJ. Myofascial Pain Syndrome in Chronic Back Pain Patients, Korean J Pain. 2011 June; 24(2): 100–104 available in full online at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111556/.)
Chen et al. showed: “The prevalence of [myofascial pain syndrome] MPS among chronic back pain patients was 63.5% (n = 80). Secondary MPS was more common than primary MPS, making up 81.3% of the total MPS.” It was especially prevalent in females.
[Author’s comment: The figure of 63.5% is surprisingly high. It casts a major new light on the problem of low back pain, which is so prevalent in general practice. It should give pause to rethink many cases of back pain which are so often written off as being mechanical in nature.]
The radiation of trigger point pain in these patients is neurological in nature, and its presence, should logically give rise to doctors to start to think of back pain as being as much of neurological issue as it is an orthopaedic and mechanical issues.
At the very least it would appear reasonable to introduce trigger point examination as being part and parcel of the basic physical examination of back pain patients in the offices of general practitioners, orthopaedic surgeons, neurologists, chiropractors and physiotherapists. A logical starting point might be to do the standard 18 fibromyalgia tender points noting how many trigger points are also. As well, it makes sense to look for additional trigger points in the general regions of the patient’s worst pains. Busy orthopaedic surgeons may be pressed for time to do the full formal tender point or targeted trigger point exam at the outset. However, it is reasonable to at least begin with a screening test of thumb pressure at 2-4 kg of force at regional MPS trigger points as well as to a smattering of fibromyalgia tender points on both sides of the body including areas that are far removed from the main site of the patient’s pain. The reason for this is to try to form an impression as to if the patient has a widespread disorder of their pain system or merely a localized disorder.
rTMS treatment of myofascial pain syndrome
A study of 10 sessions of rTMS on women with chronic myofascial pain syndrome showed the following effects:
- reduced daily pain scores by -30.21%
- reduced analgesic use by -44.56
- enhanced the corticospinal inhibitory system (41.74% reduction in quantitative sensory testing + conditioned pain modulation, P<.05)
- reduced the intracortical facilitation in 23.94%
- increased the motor evoked potential in 52.02%
- 12.38 ng/mL higher serumBDNF
The authors added that: “No adverse events were observed.” They concluded that “rTMS analgesic effects in chronic myofascial pain syndrome were mediated by top-down regulation mechanisms, enhancing the corticospinal inhibitory system possibly via BDNF secretion modulation.”
High-frequency rTMS analgesic effects were mediated by top-down regulation mechanisms enhancing the corticospinal inhibitory, and this effect involved an increase in BDNF secretion. (Repetitive transcranial magnetic stimulation increases the corticospinal inhibition and the brain-derived neurotrophic factor in chronic myofascial pain syndrome: an explanatory double-blinded, randomized, sham-controlled trial. Dall'Agnol L1, Medeiros LF2, Torres IL3, Deitos A1, Brietzke A1, Laste G4, de Souza A5, Vieira JL6, Fregni F7, Caumo W8. J Pain. 2014 Aug;15(8):845-55.)
[Author’s comments: On the face of it, the rTMS treatment based on this study seems promising. However considerable caution is still advised on theoretical grounds. Firstly, there is the issue of targeting the device. Howe do we know the device is not affecting other parts of the brain? There is considerable overlap between myofascial pain syndrome and fibromyalgia. Fibromyalgia has underlying sleep and psychological drivers and it is hard to imagine how rTMS would get at correcting the underlying drivers. In the opinion of the author it seems naïve to think that leaving the underlying issues uncorrected would lead to lasting improvement.]
For additional information about MPS
Pain and Disability: Clinical, Behavioral, and Public Policy Perspectives. David Simons, APPENDIX MYOFASCIAL PAIN SYNDROMES DUE TO TRIGGER POINTS, http://www.ncbi.nlm.nih.gov/books/NBK219241/.
Myofascial pain syndromes and their evaluation. Giamberardino MA1, Affaitati G, Fabrizio A, Costantini R. Best Pract Res Clin Rheumatol. 2011 Apr;25(2):185-98, available in full online at: https://www.researchgate.net/publication/51806532_Myofascial_pain_syndromes_and_their_evaluation.
Myofascial Pain Syndrome, Robert D. Gerwin, Chapter 2, Muscle Pain: Diagnosis and Treatment, S. Mense and R.D. Gerwin (eds.), Springer-Verlag Berlin Heidelberg 2010. For the full chapter click on this link: [PDF] Myofascial Pain Syndrome - Springer.
Myofascial pain and dysfunction. The trigger point manual. Simons DG, Travell JG, Simons L Lippincott Williams & Wilkins, Philadelphia, 1999. For a limited preview of the 1992 edition see: https://books.google.ca/books?id=8pGrvso0vnkC&source=gbs_book_other_versions.