Trigger Point from Wikipedia, the Free Encyclopedia Jump To
Total Page:16
File Type:pdf, Size:1020Kb
Trigger point From Wikipedia, the free encyclopedia Jump to: navigation, search Not to be confused with the "Tender points", used for fibromyalgia diagnosis.. This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. The talk page may contain suggestions. (August 2009) Trigger points or trigger sites are described as hyperirritable spots in skeletal muscle that are associated with palpable nodules in taut bands of muscle fibers. [1] Trigger point practitioners believe that palpable nodules are small contraction knots[ambiguous] and a common cause of pain. Compression of a trigger point may elicit local tenderness, referred pain, or local twitch response. The local twitch response is not the same as a muscle spasm. This is because a muscle spasm refers to the entire muscle contracting whereas the local twitch response also refers to the entire muscle but only involves a small twitch, no contraction. The trigger point model states that unexplained pain frequently radiates from these points of local tenderness to broader areas, sometimes distant from the trigger point itself. Practitioners claim to have identified reliable referred pain patterns, allowing practitioners to associate pain in one location with trigger points elsewhere. Many practitioners of chiropractic and massage therapy find the model useful, but the medical community at large has not embraced trigger point therapy. There is no consistent methodology for diagnosis of trigger points and a dearth of theory to explain how they arise and why they produce specific patterns of referred pain.[2] Contents [hide] 1 Definition 2 Myofascial pain syndrome 3 Qualities of trigger points o 3.1 Diagnosis of trigger points o 3.2 Misdiagnosis of pain o 3.3 Demonstration and identification of myofascial trigger points 4 Treatment o 4.1 Injection o 4.2 Self-treatment o 4.3 Risks 5 History o 5.1 Janet G. Travell, MD 6 See also 7 References 8 External links [edit] Definition The term "trigger point" was coined in 1942 by Dr. Janet Travell to describe a clinical finding with the following characteristics: Pain related to a discrete, irritable point in skeletal muscle or fascia, not caused by acute local trauma, inflammation, degeneration, neoplasm or infection. The painful point can be felt as a nodule or band in the muscle, and a twitch response can be elicited on stimulation of the trigger point. Palpation of the trigger point reproduces the patient's complaint of pain, and the pain radiates in a distribution typical of the specific muscle harboring the trigger point. The pain cannot be explained by findings on neurological examination. Practitioners do not necessarily agree on what constitutes a trigger point. A study by Gerwin et al. found that independent examiners were generally able to identify myofascial trigger points (MTrP), but only with sufficient training and agreement on the definition and features of MTrP's. They said: Three previous studies (Nice et al., 1992; Wolfe et al., 1992; Njoo and Van der Does, 1994) have examined this problem, and none of them could establish the reliability of MTrP examination in all of its major manifestations. ... The present study shows that four examiners can achieve statistically significant agreement, at times almost perfect agreement, about the presence or absence of five major features of the MTrP and on the presence or absence of the TrP, whether it be latent or active. This establishes the MTrP as a reliable clinical sign. The present study also shows that these features are identified with greater or lesser reliability depending on the specific feature and the specific muscle being examined. ... A training period was found to be essential in order to achieve these results.[3] A 2007 review of diagnostic criteria used in studies of trigger points concluded that there is as yet limited consensus on case definition in respect of MTrP pain syndrome. Further research is needed to test the reliability and validity of diagnostic criteria. Until reliable diagnostic criteria have been established, there is a need for greater transparency in research papers on how a case of MTrP pain syndrome is defined, and claims for effective interventions in treating the condition should be viewed with caution.[2] [edit] Myofascial pain syndrome The main innovation of Travell's work was the introduction of the myofascial pain syndrome concept (myofascial referring to the combination of muscle and fascia). This is described as a focal hyperirritability in muscle that can strongly modulate central nervous system functions. Travell and followers distinguish this from fibromyalgia, which is characterized by widespread pain and tenderness and is described as a central augmentation of nociception giving rise to deep tissue tenderness that includes muscles. Studies estimate that in 75–95 percent of cases, myofascial pain is a primary cause of regional pain. Myofascial pain is associated with muscle tenderness that arises from trigger points, focal points of tenderness, a few millimeters in diameter, found at multiple sites in a muscle and the fascia of muscle tissue. Biopsy tests found that trigger points were hyperirritable and electrically active muscle spindles in general muscle tissue.[4] [edit] Qualities of trigger points Trigger points have a number of qualities. They may be classified as potential, active/latent and also as key/satellites and primary/secondary. There are a few more than 620 potential trigger points possible in human muscles. These trigger points, when they become active or latent, show up in the same places in muscles in every person. That is, trigger point maps can be made that are accurate for everyone. An active trigger point is one that actively refers pain either locally or to another location (most trigger points refer pain elsewhere in the body along nerve pathways). A latent trigger point is one that exists, but does not yet refer pain actively, but may do so when pressure or strain is applied to the myoskeletal structure containing the trigger point. Latent trigger points can influence muscle activation patterns, which can result in poorer muscle coordination and balance. Active and latent trigger points are also known as "Yipe" points, for obvious reasons. A key trigger point is one that has a pain referral pattern along a nerve pathway that activates a latent trigger point on the pathway, or creates it. A satellite trigger point is one which is activated by a key trigger point. Successfully treating the key trigger point often will resolve the satellite and return it from being active to latent, or completely treating it too. In contrast, a primary trigger point in many cases will biomechanically activate a secondary trigger point in another structure. Treating the primary trigger point does not treat the secondary trigger point. Activation of trigger points may be caused by a number of factors, including acute or chronic muscle overload, activation by other trigger points (key/satellite, primary/secondary), disease, psychological distress (via systemic inflammation), homeostatic imbalances, direct trauma to the region, accident trauma (such as a car accident which stresses many muscles and causes instant trigger points) radiculopathy, infections and health issues such as smoking. Trigger points form only in muscles. They form as a local contraction in a small number of muscle fibers in a larger muscle or muscle bundle. These in turn can pull on tendons and ligaments associated with the muscle and can cause pain deep within a joint where there are no muscles. When muscle fibers contract, they use biochemical energy, and these depleted biochemicals become fatigue toxins such as lactic acid. The tightened muscle fibers constrict capillaries and prevent them from carrying off the fatigue toxins to the body's recycling system (liver and kidneys)[citation needed] . The buildup of these toxins in a muscle bundle or muscle feels like a tight muscle -- a slippery elongate bundle. When trigger points are present in muscles there is often pain and weakness in the associated structures. These pain patterns in muscles follow specific nerve pathways and have been readily mapped to allow for identification of the causative pain factor. Many trigger points have pain patterns that overlap, and some create reciprocal cyclic relationships that need to be treated extensively to remove them. [edit] Diagnosis of trigger points Trigger points are diagnosed by examining signs, symptoms, pain patterns and manual palpation. A 2009 review of nine studies examining the reliability of trigger point diagnosis found that physical examination could not be recommended as reliable for the diagnosis of trigger points.[5] Usually there is a taut band in muscles containing trigger points, and a hard nodule can be felt. Often a twitch response can be felt in the muscle by running your finger perpendicular to the muscle's direction; this twitch response often activates the "all or nothing" response in a muscle that causes it to contract. Pressing on an affected muscle can often refer pain. Clusters of trigger points are not uncommon in some of the larger muscles, such as the gluteus group (gluteus maximus, gluteus medius, and gluteus minimus). Often there is a heat differential in the local area of a trigger point, and many practitioners can sense that. In 2007, a paper was presented describing images of trigger points taken by modified MRI.[6] [edit] Misdiagnosis of pain The misdiagnosis of