This is an important question for Dry Needling Therapists and indeed anyone treating Myofascial pain.
What is a Myofascial trigger point is one of those questions that we all assume we know the answer to but we don’t necessarily test our understanding until we are questioned by our colleagues and peers.
I was one of those who assumed that my definitions and criteria for a trigger point (TrP) was similar to those of my colleagues but I wasn’t sure, and I was interested in learning if indeed my understanding and beliefs about myofascial trigger points would hold true when pooled together with other opinions from around the world. This is why I agreed to be part of an International Delphi Study into the criteria of Myofascial Trigger Points.
A Delphi Study or method is a technique that researchers use to establish consensus about a certain question or problem among experts in the field of study.
The International Delphi Study into TrP Criteria has now concluded. The results are presented in a paper by Fernández & Dommerholt and published in the journal, Pain Medicine.
So what did the Myofascial Trigger Points study find?
Before we discuss the findings, I think it’s useful to list the reasons why this study was undertaken. This will highlight the challenges with our current understanding of TrP’s within the context of myofascial pain.
- No consensus on essential diagnostic or classification criteria for diagnosing a TrP
- There’s discrepancies in the diagnostic criteria for Myofascial Pain Syndrome
- TrP diagnostic criteria have varied over time, and only a few of these criteria are now considered diagnostically relevant
- Poor reliability of diagnostic criteria for TrP’s
- Previous studies haven’t appreciated the need for assessing TrP’s with respect to a cluster of criteria rather than one criterion
- There’s a growing interest in TrP’s and their role in MPS by research networks (ACTIION*), government bodies (United States FDA*) and pain experts (APS*). We need a “gold” standard definition to help us better classify, record and research this important area of study.
Given these challenges, 65 International experts were selected from 12 countries around the world to help achieve consensus and forge a new common understanding about TrP’s and diagnostic criteria in myofascial pain. The majority of experts were from the United States, Switzerland and Italy.
The experts were asked about the basic criteria of a TrP in Round 1 of the study. 70% of the experts agreed on the following essential criteria for TrP diagnosis:
- A taut band
- Hypersensitive spot
- Referred Pain
60% of the experts agreed that a combination of these criteria was important for myofascial TrP diagnosis.
Interestingly, only 31.5% thought that a Local Twitch Response was an essential criterion.
What about the differences between active and latent trigger points?
Here an overwhelming number of experts (88.5%) thought that there were differences between these two entities.
76.7% agreed that the presence of a taut band and a hypersensitive spot should be present in both active & latent TrP’s, but the most important difference was that active TrP’s should reproduce the patient’s symptoms.
Another interesting consensus was reached regarding active TrP’s. 70% of the experts agreed that active TrP’s could be present even in patients who were not complaining of pain at the time of examination, which then means that you don’t have to complain of spontaneous pain even though you might have active TrP’s present.
What sort of referred pain?
At least 70% of the experts agreed on a description of the referred pain arising from a TrP as that spreading to a distant area, being dull & deep in nature. 60% of experts considered other descriptions like tingling and burning sensations.
Where are the TrP’s & referred pain patterns?
70% of the experts did not expect a particular pain pattern for a muscle. So does that mean we can ignore the referral patterns described by Travell and Simons?
No. Most experts agreed that these referral patterns were accurate representations of the referral patterns described by patients in clinical practice.
However, there was consensus that the ubiquitous “X” markings on the referral pattern drawings in the Trigger Point Manual by Travell and Simons was roundly considered to be unrepresentative of the location of a specific location for a TrP.
What’s the take home message about our understanding of TrP’s?
At least two of the following criteria must be present for diagnosis of TrP diagnosis:
- Taut band
- Hypersensitive spot
- Referred pain
In reference to what type of referred pain, it was agreed that the pain should spread to a distant area, be described as dull, deep, burning or tingling in nature. So, we’re not talking about referred pain so much but referred sensation.
Finally, we should place less emphasis on the presence of spontaneous pain as a distinction between active and latent pain. We should place more value of being able to reproduce a patient’s pain or referred sensations rather than spontaneous pain alone.
*ACTTION – Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Network
*FDA – Food & Drug Administration
*APS – American Pain Society
I think this is a great paper that summarise where we are with our understanding of TrP’s and their involvement in myofascial pain. If you’d like to read the paper, please see the reference below.
International Consensus on Diagnostic Criteria and Clinical Considerations of Myofascial Trigger Points: A Delphi Study.
Pain Medicine 2017; 0: 1–9 doi: 10.1093/pm/pnx207
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