Editor: Rhonda K. Kotarinos, DPT, MS and Sarah Haag
Last Updated: June 2018
Current ICS definition
Trigger point: “A tender, taut band of muscle that can be painful spontaneously or when stimulated. The taut band is electrically silent.” Foot Note - Local or referred pain may be reproduced. An active trigger point (TrP) is said to have a characteristic “twitch” response when stimulated; however, the twitch response to palpation has been shown to be unreliable. The most reliable sign of a TrP is sensitivity to applied pressure. Trigger points are implicated in myofascial pain; the validity of this theory is controversial and has recently been refuted. (1, 2)
Tender point: tenderness to palpation at soft tissue body sites (1,2)
Myalgia: muscle pain. (1)
Current expert based definition: International Delphi panel of 60 experts from 12 countries (3)
Active trigger points “an active trigger point upon stimulation reproduce any symptom experienced by the patient, either partially or completely, whereby the symptom is recognized as a familiar experience by the patient, even though it may not be present at the moment of the examination.” (3)
Latent trigger points “trigger points that upon stimulation do not reproduce any symptom experienced by a subject (symptomatic or asymptomatic) and the subject does not recognize the elicited symptom as familiar.” (3)
Diagnostic criteria include at least two of the established criteria be present to diagnose a trigger point: a taut band, a hypersensitive spot, and referred pain. (3)
The following two statements that are considered definitions by their authors are actually describing the diagnostic criteria for a trigger point, as does the IUGA/ICS proposed definition. “A hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band”(4)
Myofascial trigger point “discrete, hyperirritable nodule in a taut band of skeletal muscle that is palpable and tender during a physical examination.” (5)
Trigger point: A hyperirritable spot, usually within a taut band of skeletal muscle or in the muscle’s fascia that can give rise to characteristic referred pain, tenderness and autonomic phenomena. (6)
• A distinction between active and latent trigger points was not addressed in the 2016 IUGA/ICS paper.
• The IUGA/ICS statement about trigger points in the section on pelvic floor muscle function signs is incorrect. It states that the taut band should be tender and that is not found in any definition of listing of diagnostic criteria. There is to be a specific tender spot within the band not the whole band.
• Some clinicians use the terms trigger point, tender point and myalgia interchangeably. This is not physiologically accurate and can create confusion especially in the case of condition specific treatments. Clinicians should be clear in the use of myalgia or tender point when there is tenderness without a node and taught band. Tenderness of a structure other than muscle (ie tendon, ligament, joint line, scar) should be called tender point where tenderness of the muscle is called myalgia.
• Diagnosis of TrP - diagnosis must be reliable and reproducible and represent a distinct physiological condition. Some feel this does not exist for TrP. Advances are being made in diagnosing myofascial TrPs but are not currently readily accessible clinically.
o Other than palpation there are no currently accepted criteria for finding or describing a myofascial trigger point. There are three criteria that are essential to the diagnosis of a myofascial TrP: taut band within a muscle, exquisite tenderness at a point on the taut band and reproduction of the patient’s pain. (7) Utilizing the diagnostic criteria of the presence of a taut band, sensitive spot, local twitch response and referred pain has been shown in recent studies to have moderate to excellent reliability. (8, 9)
o Other diagnostic criteria are being investigated, such as use of ultrasound to view twitch response (10), utilizing magnetic resonance elastography (MRE) to identify taut bands, (11), tissue compliance meter which measures stiffness (2), and needle electromyography (12, 13, 14). None of these options are viable for clinical diagnosis of suspected trigger points.
o Biomechanical markers are also being investigated in and around TrPs (15, 16)
Bo K, Frawley HC, Haylen BT, et al. An International Urogynecological Association (IUGA)/ International Continence Society (ICS) joint report on the terminology for the conservative and nonpharmacological management of female pelvic floor dysfunction. Neurourol Urodynam 2016; 9999: 1-24.
Doggweiler R, Whitmore KE, Meijlink JM, Drake MJ, Frawley H, Nordling J, Hanno P, Fraser MO, Homma Y, Garrido G, Gomes MJ, Elneil S, van de Merwe JP, Lin AT, Tomoe H. A standard for terminology in chronic pelvic pain syndromes: A report from the chronic pelvic pain working group of the international continence society. Neurourol Urodyn. 2017 Apr;36(4):984-1008. doi: 10.1002/nau.23072. Epub 2016 Aug 26.
Fernandez-de-las-Penas C, Dommerholt J. International Consensus on Diagnostic Criteria and Clinical Considerations of Myofascial Trigger Points: A Delphi Study. Pain Medicine, 2017; 0: 1-9.
Simons DG, Travell JG, Simons LS. Myofascial Pain and Dysfunction: The Trigger Point Manual Vol. 1 Upper Half of Body. 2nd ed. Baltimore: Williams & Wilkins; 1999.
Shah JP, et al. Myofascial Trigger Points Then and Now: A Historical and Scientific Perspective. PM R, 2015:7(7):746-761.
Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual Vol. 1 The Upper Extremities. Baltimore: Williams & Wilkins; 1983.
Gerwin RD. Diagnosis of Myofascial Pain Syndrome. Phys Med Rehabil Clin N Am, 2014: (25):341-355.
Mora-Relucio, Nunez-Nagy S, Gallego-Izquierdo T, et al. Experienced versus inexperienced interexaminer reliability on location and classification of myofascial trigger point palapation to diagnose lateral epicondylalgia: An observational cross-sectional study. Evid Based Complement Alternat Med 2016; 606597 19.
Sanz Dr, Lobo Dl, et al. Inter-rater reliability in the clinical evaluation of myofascial trigger points in three ankle muscles. J Manipulative Physiol Ther 2016;39:623-34.
Sikdar S, et al. Assessment of myofascial trigger points (MTrPs): a new application of ultrasound imaging and vibration sonoelastography. Proceedings of the 30th annual International IEEE EMBS Conference. Vancouver (Canada): 2008.
Chen Q, et al Quantification of myofascial taut bands. Arch Phys Med Rehabil. 2016: 97:67-73.
Hubbard DR, Berkoff M. Myofascial trigger points show spontaneous needle EMG activity. Spine. 1993: 18:1803-1807.
Simons DG, Hong CZ, Simons LS. Prevalence of spontaneous electrical activity at trigger points and at control sites in rabbit skeletal muscle. J Muscoskel Pain. 1995:3(1):35-48.
Hong CZ, Simons DG. Pathophysiologic and electrophysiologic mechanisms of myofascial trigger points. Arch Phys Med Rehabil. 1998: 79:634-640.
Shah JP, et al An in vivo microanalytical technique for measuring the local biochemical milieu of human muscle. J Appl Physiol. 2005:99:1977-1984.
Shah JS, et al Biochemicals associated with pain and inflammation are elevated in sites near to and remote from active myofascial trigger points. Arch Phys Med Rehabil. 2008:89:16-23.