Two articles on PainSci cite Simons 2002: 1. The Complete Guide to Trigger Points & Myofascial Pain 2. The Trigger Point Identity Crisis
PainSci commentary on Simons 2002: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.
This study is one of only two direct, simple investigations of the electrical characteristics of trigger points, usually referred to as endplate noise or spontaneous electrical activity (SEA).
End plate potentials (EPPs) are the waves of electrical activity that spread out from the point where motor neurons attach to muscles (which have a distinctive saucer-like appearance). EPPs can be measured with electrodes on the skin, or a probe inserted into the muscles. This is electromyography (EMG).
Simons, Hong, and Simons looked for three kinds of EPPs at trigger points, in the taut bands of muscle found with them, and endplate zones (the neuromuscular junction). They examined one test site and two control sites in eleven muscles in ten subjects. They found endplate “noise” at all the trigger points, in four muscles at endplate zones away from TrPs, and nowhere else. The closer they were to a TrP, the more endplate noise they found. They concluded that “endplate noise seems to be characteristic of, but is not restricted to, the region of a myofascial trigger point.”
Note that electromyography can be tricky — here be dragons — and there is plenty of room for errors in technique and interpretation. It certainly needs independent replication. Nevertheless, this evidence is suggestive.
~ Paul Ingraham
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
OBJECTIVES: To compare the prevalence of motor endplate potentials (noise and spikes) in active central myofascial trigger points, endplate zones, and taut bands of skeletal muscle to assess the specificity of endplate potentials to myofascial trigger points.
DESIGN: This nonrandomized, unblinded needle examination of myofascial trigger points compares the prevalence of three forms of endplate potentials at one test site and two control sites in 11 muscles of 10 subjects. The endplate zone was independently determined electrically. Active central myofascial trigger points were identified by spot tenderness in a palpable taut band of muscle, a local twitch response to snapping palpation, and the subject's recognition of pain elicited by pressure on the tender spot.
RESULTS: Endplate noise without spikes occurred in all 11 muscles at trigger-point sites, in four muscles at endplate zone sites outside of trigger points (P = 0.024), and did not occur in taut band sites outside of an endplate zone (P = 0.000034).
CONCLUSIONS: Endplate noise was significantly more prevalent in myofascial trigger points than in sites that were outside of a trigger point but still within the endplate zone. Endplate noise seems to be characteristic of, but is not restricted to, the region of a myofascial trigger point.
- “Microscopic features and transient contraction of palpable bands in canine muscle,” D G Simons and W C Stolov, Am J Phys Med, 1976.
- “Accelerated muscle fatigability of latent myofascial trigger points in humans,” Hong-You Ge, Lars Arendt-Nielsen, and Pascal Madeleine, Pain Med, 2012.
- “Two-dimensional ultrasound and ultrasound elastography imaging of trigger points in women with myofascial pain syndrome treated by acupuncture and electroacupuncture: a double-blinded randomized controlled pilot study,” Cristina Emöke Erika Müller, Maria Fernanda Montans Aranha, and Maria Beatriz Duarte Gavião, Ultrason Imaging, 2015.
- “Induction of muscle cramps by nociceptive stimulation of latent myofascial trigger points,” Hong-You Ge, Yang Zhang, Shellie Boudreau, Shou-Wei Yue, and Lars Arendt-Nielsen, Exp Brain Res, 2008.
- “Assessment of myofascial trigger points (MTrPs): a new application of ultrasound imaging and vibration sonoelastography,” Siddhartha Sikdar, Jay P Shah, Elizabeth Gilliams, Tadesse Gebreab, and Lynn H Gerber, Conf Proc IEEE Eng Med Biol Soc, 2008.
- “Uncovering the biochemical milieu of myofascial trigger points using in vivo microdialysis: an application of muscle pain concepts to myofascial pain syndrome,” Jay P Shah and Elizabeth A Gilliams, Journal of Bodywork & Movement Therapies, 2008.
- “Ability of magnetic resonance elastography to assess taut bands,” Qingshan Chen, Jeffrey Basford, and Kai-Nan An, Clin Biomech (Bristol, Avon), 2008.
- “Spinal cord mechanism involving the remote effects of dry needling on the irritability of myofascial trigger spots in rabbit skeletal muscle,” Yueh-Ling Hsieh, Li-Wei Chou, Yie-San Joe, and Chang-Zern Hong, Archives of Physical Medicine & Rehabilitation, 2011.
- “Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagation,” Hong-You Ge, César Fernández-de-Las-Peñas, and Shou-Wei Yue, Chin Med, 2011.
- “The myofascial trigger point region: correlation between the degree of irritability and the prevalence of endplate noise,” Ta-Shen Kuan, Yueh-Ling Hsieh, Shu-Min Chen, Jo-Tong Chen, Wei-Chang Yen, and Chang-Zern Hong, Am J Phys Med Rehabil, 2007.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Exercise and education versus saline injections for knee osteoarthritis: a randomised controlled equivalence trial. Bandak 2022 Ann Rheum Dis.
- Association of Lumbar MRI Findings with Current and Future Back Pain in a Population-based Cohort Study. Kasch 2022 Spine (Phila Pa 1976).
- A double-blinded randomised controlled study of the value of sequential intravenous and oral magnesium therapy in patients with chronic low back pain with a neuropathic component. Yousef 2013 Anaesthesia.
- Is Neck Posture Subgroup in Late Adolescence a Risk Factor for Persistent Neck Pain in Young Adults? A Prospective Study. Richards 2021 Phys Ther.
- Sudden amnesia resulting in pain relief: the relationship between memory and pain. Choi 2007 Pain.