Diagnosis & Clinical Meaning of Myofascial Trigger Points: "Advances" from 1940s to 2023

The term "trigger point" has been used since 1942 when Dr. Janet Travell coined it to describe the hyperirritable spots in skeletal muscle, not caused by acute local trauma, inflammation, degeneration, neoplasm or infection. The point can be felt as a nodule or band in the muscle, and a twitch response can be elicited on stimulation of this point (Travell JG et al, 1999).

Dr. Travell also outlined diagnostic criteria and treatment protocols, which became the underlying foundation for treatment of myofascial pain today. In a work co-published by Dr. Travell and Dr. David Simons, all trigger points and the associated zones of radiating pain are mapped in nearly every muscle of the body (Travell JG et al, 1999).

However, 80 years has passed since the diagnostic criteria established, practitioners and researchers today are still unable to agree on what constitutes a trigger point.

19 Opinions: Which Is The Right One?

A 2007 review (Tough EA et al, 2007) identified 19 different diagnostic criteria used by different researchers or clinicians.

The 4 most commonly applied criteria were: "tender spot in a taut band" of skeletal muscle, "patient pain recognition," "predicted pain referral pattern," and "local twitch response."

There was no consistent pattern to the choice of specific diagnostic criteria or their combinations. However, one pair of criteria "tender point in a taut band" and "predicted or recognized pain referral" were used by over half the studies.

The great majority of studies cited publications by Travell and more recently Simons as a principal authoritative source for MTrP pain syndrome diagnosis, yet most of these studies failed to apply the diagnostic criteria as described by these authorities.

A Diagnosis With No Reliability at All

A 2009 review (Lucas N et al, 2009) of 9 studies examining the reliability of trigger point diagnosis found:

• None of the 9 studies satisfied all quality and applicability criteria.
• No study specifically reported reliability for the identification of the location of active trigger points in the muscles of symptomatic participants.
• Reliability estimates varied widely for each diagnostic sign, for each muscle, and across each study.

The review concluded:

• Physical examination cannot currently be recommended as a reliable test for the diagnosis of trigger points.

A Theory Led to Little Clinical Benefits

80 years passed since TrP as a cause for myofascial pain was first time described (in 1942), it has not led to any remarkable clinical benefit yet.

TrP theory is widely used to guide the usage of dry needling (DN) in pain management. A 2017 systematic review investigated the efficacy of TrP DN performed by physical therapists (Gatti E et al, 2017) in pain management. The conclusion:

• Very low-quality to moderate-quality evidence suggests that dry needling performed by physical therapists is more effective than no treatment, sham dry needling, and other treatments for reducing pain..,

• Low-quality evidence suggests superior outcomes with dry needling for functional outcomes when compared to no treatment or sham needling.
• No difference in functional outcomes exists when compared to other physical therapy treatments.
• Evidence of long-term benefit of dry needling is currently lacking.

In 2019, 6 physiotherapy researchers from USA reported the results of their systematic review on the efficacy of manual therapy, dry needling and dry cupping for treatment in short-term relief of myofascial pain and myofascial trigger points (Derek Charles et al, 2019).

33 studies were included, among which, 8 studies on manual therapy, 23 studies on dry needling, and 2 studies on dry cupping. The Physiotherapy Evidence Database (PEDro) was utilized to assess the quality of all studies.

The review concluded:

• There is moderate evidence for manual therapy in myofascial pain treatment,
• The evidence for dry needling and cupping is not greater than placebo.
• Future studies should address the limitations of small sample sizes, unclear methodologies, poor blinding, and lack of control groups.

Most recently in 2023, 8 researchers from Germany, Brazil, Canada, Malaysia reported the results of their systematic review (Franke Muggeborge et al, 2023). The review investigated the effectiveness of manual trigger point (MtrP) therapy in the orofacial area in patients with or without orofacial pain. Four studies were included.

The review found:

• The overall quality/certainty of the evidence was very low due to the high risk of bias.
• Manual trigger point therapy showed no clear advantage over other conservative treatments, but better than control groups.
• Rigorous, well-designed RCTs are still needed in this field.

An Obvious Dead End. But We Prefer Stay With It

We have spent 80 years in examining, investigating and testing a theory established on an episodic finding related to an abnormal morphology of muscle. But the theory has advanced to nowhere.

Science shows that we human often prefer to stay with status quo rather than take a risk to accept things we are not familiar with. It is called 'status quo bias' in our brain: the more difficult the decision we face, the more likely we are not to act.

We only see parts of the world. We tend to draw conclusions from sparse data and use cognitive shortcuts to create a version of reality that we implicitly want to believe in. This creates a reduced stream of incoming information, which helps us connect dots and fill in gaps with stuff we already know (Pragya Agarwal, 2023). .

Ultimately, our brains are lazy and it takes a lot of cognitive effort to change the script and these shortcuts that we have already built up.

Dead End Theories: TrP Is Not Alone

Myofascial TrP, an obvious dead end we prefer to stay in. A same scenario as meridians in acupuncture, subluxation in spinal therapy, "like for like" in herb usage, "tight muscle" or "bad posture" in pain relief... and the list goes on....

In physical science, we can send a man to the moon. In molecular biology and biochemistry, we are almost able to clone a human. But in musculoskeletal medical science, we are still unable to reduce a patient's back pain more than a placebo does.

A Way to Get out

Is there is a way to get out of the TrP dead end? At least a chiropractor's eye-opening findings and his definition of “trigger point” in a much broad sense presented a good hint, which may help us reduce our "status quo bias". I will talk about it in my oncoming posts. Stay with me.

References

Derek Charles et al, A systematic review of manual therapy techniques, dry cupping and dry needling in the reduction of myofascial pain and myofascial trigger points,Journal of Bodywork and Movement Therapies, Volume 23, Issue 3,2019, Pages 539-546,

Frauke Müggenborg et al, Effectiveness of Manual Trigger Point Therapy in Patients with Myofascial Trigger Points in the Orofacial Region—A Systematic Review. Life 2023, 13(2), 336;

Lucas N, Macaskill P, Irwig L, Moran R, Bogduk N. Reliability of physical examination for diagnosis of myofascial trigger points: a systematic review of the literature. Clin J Pain. 2009 Jan;25(1):80-9.

Pragya Agarwal, How the brain stops us learning from our mistakes – and what to do about?it. 2023, www.positive.news/lifestyle/wellbeing/how-to-learn-from-mistakes/

Tough EA et al, Variability of criteria used to diagnose myofascial trigger point pain syndrome--evidence from a review of the literature. Clin J Pain. 2007 Mar-Apr;23(3):278-86. doi: 10.1097/AJP.0b013e31802fda7c. PMID: 17314589.

Travell JG et al, Travell & Simons' myofascial pain and dysfunction : the trigger point manual. 1999

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