A Trigger Point Review

A Trigger Point Review

Trigger points (TrPs) are a common source of discussion and debate on social media.  Arguing dogmatic beliefs is not my intention. Because this often leads to polarisation and then the intended message is lost. As a regulated healthcare profession in Canada, Massage Therapists must follow the evidence rather than holding strongly to outdated and unsupported opinions. This blog was written to explore the current TrP evidence. By ignoring the evidence, the profession is doing a disservice to itself, and most importantly to the public who seek our care and support.

“I pulled this image off the internet a while ago so I apologize for the lack of reference to its creator.”

The One About Trigger Points

What is a trigger point?  What causes them? How does a clinician accurately assess for them?  What works best for treating them?

For this blog, I have combed through a wealth of TrP research papers and I will use this information to do my best to answer these questions for you .

Trigger point introduction

Pain experienced in voluntary muscles originating from myofascial tissues was an idea initially proposed by Travell and Rinzler in 1952. This idea was formalised by Travell and Simons in 1983.  This is when the familiar big red books were first published.

It may be surprising to some that nobody really knows what a trigger point is.  There are a few different hypotheses.  However, there is not a standardized definition or accepted understanding of what they are or what causes them. What can everyone agree on? A trigger point is a sore spot.  Do they reside in muscle tissue, fascia, skin, nervous tissue, all of the above? Nobody has a solid answer.

This explanation below resonated with me.  It can be found in the systematic review and meta-analysis by Denneny et al (2018) here:

Myofascial pain syndrome and TrPs are, “considered a form of neuromuscular dysfunction, consisting of soft tissue and sensory abnormalities, involving both peripheral and central nervous systems. Referred pain, a characteristic of TrPs, is postulated to be a central phenomenon initiated and activated by peripheral sensitization, whereby peripheral nociceptive input from muscle can sensitize previously silent dorsal horn neurons.”

This definition includes a neurophysiological explanation which emphasizes the inter-relationship between soft tissue, nociceptive systems and the nervous system.  This appears consistent with the current understanding of nociception and pain. This explanation doesn’t include a causal relationship or a hypothesis about where TrPs come from.  My assumption, this is because the authors do not have any evidence to make a claim about the cause of TrPs.  This is honourable and expected by those in the academic community.

Travell and Simon’s explanation was a hypothesis with minimal physiological or scientific backing. Translation = it was an idea based on limited evidence. Travell had created a story to help explain her clinical experience. A clinical phenomena was observed (sore spots), a hypothesis was created to help explain it (original TrP hypothesis), and then a treatment protocol was created (ischemic pressure, spray and stretch, injection). Travell’s reasoning was biomedical, but this is not surprising as biomedical reasoning for all MSK problems was the dominant narrative and approach to care at the time. This is not an attack on Travell or early pioneers of TrP therapy.  Judging them based on today’s knowledge is unfair. The unfortunate reality is these ideas and teachings are still taught to generations of MTs.  If MTs have the desire to be evidence-based and want to be part of modern healthcare best practices, it is necessary to challenge many established assumptions.

Importance of Challenging Common Assumptions

Humans have a need to make sense of their environment.  Stories are a good way to do that. In healthcare, stories without evidence is not okay.  Stories without a strong basis in known physiology deserve to be scrutinised because people’s lives and well-being deserve better. If Travell’s explanation of TrPs were valid then decades later one would expect there to be a universally accepted understanding of what TrPs are, how to assess for them, and more importantly, how to consistently and effectively treat them.  If TrPs could be consistently diagnosed and treated like other conditions, such as osteoarthritis or a ligament sprain, then this topic would have limited need for scepticism or debate.

One of the clinical reasoning errors I frequently see is when clinicians extrapolate anatomical knowledge into something that is clinically meaningful. Grand claims about the importance of certain anatomical structures or the importance of treating specific anatomy is a common misconception in MSK treatment and management.  It may sound crazy to some, but clinicians cannot change anatomy with their hands.  Anatomy matters very little in MSK pain and disability.  Anatomy does not need to change for people to feel better.  This statement requires some references.  Jeremy Lewis and Peter O’Sullivan here. Lewis also has some great papers challenging common shoulder assessments and pathologies.  Jill Cook, Ebonie Rio, Craig Perdum and others are the ones to follow for tendinopathy research here. Peter O’Sullivan for the low back here. There is a wealth of research over the past quarter century that is pushing the MSK pain narrative away from anatomy and structure and towards a more encompassing biopsychosocial conceptual framework.  Following the evidence suggests clinicians move away from pathoanatomical, structural or soft tissue reasoning for pain.  TrPs are part of this anatomical obsession for pain treatment and do not fit well into the current evidence base.

Feeling uncomfortable with that last paragraph?  That’s okay.  Many people hear that and feel invalidated.  You are still helping people, but the reason for that is likely very different than what you were taught in school or other continuing education courses.

Clinical experience.  

This is a very important part of the evidence based framework.  However, clinical success does not  validate the mechanism of success!  A clinical approach that provides a desirable outcome only shows an outcome, it does not support a mechanism. This is important for clinicians to understand.  The claim of, “my treatment works and I don’t care what you say, or, I spent 5 years in osteopathy school in addition to my 3000 hour RMT training so if you want to know more maybe you should do the same,”  are childish arguments that do nothing to further dialogue or knowledge.  If clinicians started to look at the similarities in what they do rather than looking at the differences, the push towards an evidence based profession would be a little bit further forward.

My advice. Be sceptical, question everything.  Curiosity will keep you engaged and interested in your personal and professional development.  Always ask for evidence to support claims.  Do not blindly accept what you hear as truth.  This way of thinking may lead to a sense of nihilism, but this is healthier than acceptance of something because it sounds interesting or confirms a bias.

What causes trigger points? How to identify them?

Back to the TrP science …

TrP’s are frequently thought to be relevant for the cause and perpetuation of most soft tissue pain. Headaches, spinal, hip, leg, arm, face, pelvic pain. Name a region of the body and if pain is experienced there, someone is likely to diagnose it as TrPs. Travell and Simons original hypothesis was TrPs are small muscle cramps which decrease local blood supply and this creates metabolic buildup. Anyone who has access to Travell’s books can read into more details about this. It was also believed that TrPs could spread causing secondary TrPs to develop in areas away from the initial symptom site.  It should be emphasized, this has never been substantiated with research. This idea has been around for decades now and is often believed to be factual. Say something enough times with enough conviction and it starts to be seen as truthful.  Anyone who pays attention to politics will be familiar with this way of spreading misinformation :-).

In an attempt to find out what mechanism(s) are responsible for the creation and perpetuation of TrPs researchers have investigated a number of hypotheses.

In 2 studies by Shah et al, here and here they investigated tissue biochemistry. This showed elevated levels of inflammatory markers in areas of reported TrPs.  However, in asymptomatic controls, which were distal from the painful site, these same markers were also found. A possible reason for this finding?  The needles used to measure the biochemistry caused inflammation during their insertion.  Or it could be the result of inflamed peripheral nerves?

An EMG study here found, “no electrodiagnostic evidence of ongoing denervation or focal muscle spasm is found in association with focal myofascial pain.”

Imaging studies using various technologies were also unremarkable.  This research is summarised well in a critical review here.

A popular explanation is the integrated hypothesis.  Dommerholt et al and Gerwin et al have written extensively on this idea here, here and here.  They hypothesised that taut bands could produce muscle ischemia which could compress adjacent capillaries supplying the muscle. These taut bands were thought to occur because of excessive acetylcholine released by dysfunctional neuromuscular end-plates. This physiological process could precipitate an energy crisis in the relevant working muscle, which would respond by releasing pro-inflammatory molecules, thereby activating nociceptive neurons.  This sounds complicated, and could be a plausible explanation.  However, there is limited scientific evidence in support.

A more recent hypothesis is that trigger points could be the result of irritated cutaneous nerves.  See Quintner et al here. This cutaneous nerve hypothesis feels like a step in the less wrong direction. The problem with this idea is it still lacks a causal mechanism.  If cutaneous nerves are the nociceptive driver to the pain experience, what is causing the cutaneous nerves to be inflamed? In my opinion this question needs to be answered.

A very readable summary of the debates that ensued between Dommerholt et al and Quintner and Cohen can be found here.

How to treat trigger points?

For the clinician this should be the most important item in this blog.  TrPs are a clinical entity, that can be agreed on. However, what is the most effective way to treat them? Take your pick. TrPs can be pressed on, stretched, iced, heated, injected or even surgically removed !

Before a TrP can be treated, how is it identified/diagnosed? Palpable taut bands of muscles, localized twitch responses, weakness on strength testing, and decreased muscle extensibility are all proposed diagnostic ideas. This is performed through accurate palpation.  However, when you look at the large data on this topic, here,  it suggests that diagnostic accuracy through palpation is severely lacking. The lack of inter-rater reliability for clinicians to accurately palpate a TrP suggests that accurate treatment of them might be difficult too!

Is this person pictured above getting an upper trapezius TrP treated? Probably doesn’t matter.  As long as it feels good!

Are injection therapies effective?  Not really.  A 2005 study here, injected botulism toxin, a very powerful analgesic and muscle relaxant.  The results were unsupportive.  These findings are consistent with large trials of dry needling and other injectable substances.  Outcomes are not great.  It appears that doing something is better than nothing, but not much better.

Spend enough time on social media and you can find MSK therapists giving endless suggestions on how to most effectively treat any soft tissue presentation.  Some clinicians swear they use the best technique, approach or strategy that “worked for hundreds/thousands of my patients.”   The question I ask is,  “If one is right and one is wrong, then why do both claim to have similar outcomes?”

What is the current state of the research on the effectiveness of manual treatment of TrPs? Not great 🙁 .  A 2018 systematic review here, suggests that as a standalone treatment they are not recommended in the treatment of chronic pain.  The key wording here is standalone.  Incorporating TrP therapy into an overall person centred treatment framework that included self-management strategies could be an evidence based approach to care.  Which is likely what most MTs regularly do in their practices.

Why do some people benefit with TrP therapy if the evidence suggests otherwise?

If we take the 30,000 foot view of the situation it makes things clearer. The entire biopsychosocial package of the treatment interaction is the evidence based approach that should be embraced. It is not the specificity of the intervention that is the most effective, otherwise all these different approaches would never provide a meaningful outcome. It is the complex interactions between both individuals in a respectful and meaningful context that is more likely to provide relief.  Touch that is important, which feels good, and which provides the necessary sensory input should be the objective. It is the trust, treatment ritual, meaningful touch/massage combined with expectations from both the person getting treatment and the clinician which is more powerful than a singular technique.  A 2019 article on the role of touch in MSK care can be found here.

This may sound dismissive.  However, I view it as increasing clinical options, not dismissing them.  The research does not give us strong evidence at the efficacy for treating trigger points.  Yet we all have clinical experiences which suggests that treating people’s sore spots can be helpful.  Maybe the exact mechanisms of the treatment effect are not well understood?  This doesn’t negate the impact that doing something helps most.  Being an evidence based clinician requires an awareness of the potential to do harm.  The evidence based MT should take the least invasive route rather than the most invasive.  Maybe TrPs are an irritated cutaneous nerve and there is neurogenic inflammation present?  This idea doesn’t give us a solid understanding of what causes them, but, if this is a possible factor then clinician’s must be mindful of how pushing and poking at an irritated nerve would not be a good idea.  Nerves can be sensitive and don’t like being squished and poked.  They can respond to this mechanical assault by becoming more sensitive and thus generating more noxious signals which may increase the likelihood that someone will experience more pain.

Moving beyond the trigger point narrative 

Following TrP logic is akin to the game of “whack a mole.”  Searching for painful areas to press on, only to have them pop up again later in the same place or somewhere else close by. Clinical treatments are often aggressive and painful.  Common self-care is to squish, mash and stretch the sore spots. This constant noxious sensory input is not recommended in pain treatment/management.  It may provide limited relief, but the symptoms inevitably return. With an appreciation for how the nociceptive and pain processing systems work it is no surprise that TrP therapy works no better than other interventions.  FYI, all manual therapy interventions on their own produce similar results which can be summarised as, meh, not great.

Does this mean clinicians should just ignore a clinical “TrP/sore spot” when they come across one?  Of course not!  What the research is suggesting is that sore spots can be a piece of the overall pain puzzle.  But, they are not the complete solution to the puzzle.  Maybe the person who seeks your support and care could benefit from an approach that isn’t poky and painful?  Maybe you can treat the sore area(s) without flaring it up, touch it nicely.  I often joke about branding a style of manual therapy as TPN, Touch People Nicely 🙂 Nice, is a very subjective term. What feels good will be different for everyone.  Be curious, explore touch, try some subtle movements.  If it feels good, positive, nice, then that is more likely to be the least wrong treatment. Don’t be afraid to incorporate lots of movements.  Simple active and passive ROM and contract/relax can be analgesic. Self-management should be more encompassing than self-massage.  Ask people what activities feel good.  Encourage those.  Simple movement explorations can often be a very powerful pain management tool.

The Red Books? Further Reading

My advice to any aspiring, rookie, or seasoned clinician, is to disregard the red books.  Their time is past and for the profession to become evidence based, these books need to go. From an historical perspective they have value.  However, these are expensive, not based on current science and can lead clinicians down a path of problematic clinical reasoning.

For a thorough exploration on trigger points check out Paul Ingraham’s blog here.

Want to listen to an interview we did with Paul?  Check it out here.

A recent article on this topic was written by Massage and Fitness Magazine here. 

Interested in pursuing evidence based pain and rehab education?

The ideas and research covered in this blog are some of the things explored in greater details within our workshops and professional courses.  Please visit this link below to check them out.

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Thanks for reading.

~Eric

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