Myofascial pain syndrome - Pathos

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Myofascial pain syndrome

La sindrome dolorosa miofasciale
Short review
Pathos 2020, 27; 3. Online 2020, Dec 31
___________________________________________________
Nicola Maratea
Responsabile UOSD Coordinamento attività anestesiologiche
Ospedale di Policoro, ASM Matera
____________________________________________________
Summary  Among the musculoskeletal pain syndromes, myofascial is certainly one of the most frequent. Overuse musculoskeletal pain affects 33% of adults and is responsible for 29% of work days lost due to illness. Myofascial pain syndrome (MPS) is a condition characterized by local pain is reportedly, described as dull and deep, determined by the presence of myofascial trigger points. Trigger points (TP) are areas of hypersensitivity localized in one or more muscles that evoke pain referred to at a distance in the so-called target areas. The acupressure of TP remotely evokes pain referred to in the so-called target area (or reference area) and a localized muscle contraction (twitch). The genesis of trigger points is multifactorial and includes morphological, neurotransmitter, neurosensitive and electrophysiological changes. Therapy can make use of various choices: anesthetic block of trigger points, strech and spray, localized pressure at the level of TP, non-steroidal analgesics and adjuvants such as octreotide by endocular route and active physical therapy.
Riassunto  La sindrome miofasciale è sicuramente una delle più frequenti sindromi dolorose muscoloscheletriche. Il dolore muscoloscheletrico da overuse affligge il 33 per cento degli adulti ed è responsabile del 29 per cento di giorni di lavoro perduti per malattia. La sindrome dolorosa miofasciale (MPS) è una condizione caratterizzata da dolore locale e riferito, descritto come sordo e profondo, determinato dalla presenza di trigger point miofasciali.
I trigger point (TP) sono aree di ipersensibilità localizzate in uno o più muscoli che evocano dolore riferito a distanza nelle cosiddette aree bersaglio. La digitopressione del TP evoca a distanza dolore riferito nella cosiddetta target area (area bersaglio o zona di riferimento) e una contrazione muscolare localizzata (twitch). La genesi dei trigger point è multifattoriale e comprende cambiamenti morfologici, neurotrasmettitoriali, neurosensitivi ed elettrofisiologici. La terapia può avvalersi di varie scelte: blocco anestetico dei trigger point, stretch and spray, pressione localizzata a livello dei TP, analgesici non steroidei e adiuvanti, terapia fisica attiva.
Key words Chronic, musculoskeletal, pain, trigger point, contraction, localized.
Parole chiave Dolore, cronico, muscoloscheletrico, trigger point, contrazione, localizzato.    

Introduction
Pain is a public health problem and is the most common reason for medical consultation and hospitalization.1,2 Musculoskeletal pain from overuse affects 33 percent of adults and is responsible for 29 percent of sick leave.3 Untreated or undertreated pain is associated with complications, poor patient satisfaction, and an increased risk of developing chronic pain.4
Myofascial Pain Syndrome (MPS) in acute and chronic form, is one of the most common disabling musculoskeletal pain syndromes. (Figure 1).5

Characteristics of MPS
In 1994, the IASP (International Association for the Study of Pain) taxonomy commission definitively recognized the peculiarity of this syndrome (code X33.X8a), also differentiating it from the primary fibromyalgia syndrome, with which it is often confused.
Myofascial pain syndrome includes a large and heterogeneous group of muscle diseases that present with continuous muscle pain, associated with contracture, functional limitation and, occasionally, with neuralgic-type symptoms (paraesthesia, tingling and vegetative dysfunction).
This condition is characterized by trigger points (TPs) which can be defined focus of hyperirritability, most of which are clearly identifiable. Acupressure causes intense pain with hyperpathy phenomena , such as facial grimace and retraction of the stimulated part. Evoked pain is referred pain, because it is perceived in well-defined areas, called target areas or reference areas (target area) , not in topographical continuity with the stimulated point. TPs can be active or latent.    
Active TPs: they are responsible for clinical symptoms, pain at rest and pain caused by muscle over-stretching.
Latent TPs: they cause movement limitations and weakness; pain is evoked only with moderate pressure at one point of the muscle
Pain in MPS is typically deep and unremitting, but not joint. The distribution appears generally regional and not referable to a spinal segment or a peripheral nerve. Painful areas of muscles often correspond to well-defined, palpable nodules or cords.6-9
Pressure on painful areas (myofascial trigger points) causes pain. Diagnosis of MPS is confirmed by disappearance of pain after inactivation of the trigger points obtained by one of many methods, including muscle stretching or injection of local anesthetic. Our knowledge of trigger points is largely due to the pioneering work of Kellgren7,10,11 6,9,10 who studied groups of patients with continuous and very extensive pain, the origin of which could be related to one or two muscles that had very sensitive areas.9 In theory all muscles could be TPs seat, but the most frequent and characteristic seats are neck, shoulder, back and ends. In Table 1 are reported the muscles that most frequently may show TPs, with the relative innervation and the probable associated pathologies.

Etiology
Myofascial pain syndrome mechanism is doubtful. Travell and Simons9 assumed that MPS could arise from activation of latent trigger points. It is known that a noxious stimulus, of any origin can, by reflex action, induce a muscle contraction (referred pain).11   
The characteristics of reffered pain allow to identify the muscles responsible for myofascial pain. A reference zone is present in all patients and can be associated with much larger area. This zone is called “inverted reference zone” (Spillover). Profound hyperalgesia or stiffness is often associated with pain in reference area.11
The most recognizable causes for development of trigger points are trauma to myofascial structures, muscle overload, microtrauma (usually in the workplace), excessive use of less exploited muscles.12,13  
Occasionally MPS can be attributed to a twist or excessive tension or trauma; however, often no event can be demonstrated and the patient is inaccurate on the exact date of pain onset.
The initial phase leading to the formation of a TP can be explained by the vicious circle of muscle contraction, the release of algogenic substances, the sensitization of muscle nociceptors and the activation of the sympathetic vasoactive response.
Furthermore, the scars of previous laparotomy operations, often site of trigger points, capable of radiating pain to the loins and beyond any segmental distribution, should be explored.14
 
Treatment of myofascial syndrome
Like any specialist sector, pain must also be framed in compliance with specific skills. In the context of a complex and varied clinical picture such as the myofascial pain syndrome, an algological methodology15 is essential that includes multimodal and multidisciplinary interventions, with a view to improving the quality of life, participation in the patient's therapy and less invasiveness possible. The most correct approach to follow involves a sequence of events.16
Shortly:
Reassure the patient, promote muscle relaxation and restore a good level of fitness, correct motor dysfunctions and reduce pain.16
It is important to inform the patient of his pathology, reassuring him on the non-malignancy of the same and on the need to reduce stress and to change incorrect eating and lifestyle habits. It is understood that the approach to the patient must be multidisciplinary and must take into account, in addition to the symptom, a deficit of physical and functional capacity, psychological and family problems, work and economic problems. The approach must therefore be not only analgesic but also physiatric, psychiatric, physical therapy and rehabilitation.
The primary objective is precisely to restore the highest possible functional capacity to the patient, reducing pain, the amount of drugs taken, increasing the level of activity and modifying pain reinforcement behavior. Myofascial pain treatment by blocking or trigger points deactivating is one of the most frequent problems in daily practice. The high percentage of positive results of the treatment, associated with the relative ease of the analgesic technique, constitutes great professional satisfaction. Even the physical therapy (massage, stretching exercises), therapy with analgesic non-steroidal and adjuvants by intraocular route,17 muscle stretching and refrigerant spray (stretch and spray) and stretching with TP injection (stretch and inject) may be of help.18-20     

Neural therapy
Neural therapy is based on the theory that trauma can produce long-standing alterations in electrochemical function of tissues. Properly applied neural injection therapy can often, immediately and permanently, resolve long-standing chronic disease and chronic pain. This type of instant healing is known as "lightning reaction" or " Huneke phenomenon ". The scar is considered, in neural therapeutic slang, an “interference field”.21-24
Neural therapy, therefore, appears to have a solid and important position in chronic pain treatment.

The anaesthetic block
Trigger point anaesthetic blocking remains, however, the treatment of choice. In fact, in our experience, we have verified that the application of cooling spray and simultaneous stretching of the affected muscle (stretch and spray) is not always feasible as it is not accepted by the patient especially in the winter months and in subjects who do not tolerate infiltrations. .       
In addition, spray of etilecloridrato is highly flammable, toxic and colder than necessary. It is a volatile compound that has caused accidental death of several doctors and patients. Spray of this type can be an alternative, but have the disadvantage of being potent greenhouse gas.25    
In 1979, a study by Karl Lewit noted that the dry-block (needles dry) had the same success rate of anesthetic injections for the treatment of points trigger , calling this "needle" effect.26  
To successfully treat myofascial pain, we need to know the pain distribution and localization of TPs25 and  patiently and meticulously to search for trigger areas with palpation.
For optimal results, it is important to completely eliminate all points of pain-producing hyperexcitability. Once the patient has been informed about diagnosis, type of treatment, safety, expected results and the consent has been obtained, we proceed to the blockage.
All TPs found in the diagnostic phase must already be marked with a dermographic pencil. The skin is disinfected with a quaternary ammonium base, the TP is immobilized on one side and the other with the fingers and the injection is made. The needle penetrating the TP generally evokes hyperesthesia and pain, both locally, but also in the reference area (target area). The length of the needle must be suitable for the muscle to be treated. The quality of the needle is important and to avoid harm to the patient and medico-legal consequences it is advisable to always use quality needles.
The dose of anaesthetic, usually levobupivacaine 0.25% for each point, is at least 1-2 ml of solution plus an adjuvant, usually clonidine and cortisone (water-soluble steroid).19,27
Absolutely to be banned are the "deposit" or "prolonged release" cortisone which, containing irritating and not easily absorbable substances among the excipients, end up increasing local pain, often causing annoying reactions from a foreign body.
Contraindications to this use of local anaesthetics are scarce; allergic reactions to ALs are extremely rare. Venular rhexis may occur, especially in fertile women, leading to the formation of hematomas; infiltrations will naturally be avoided in patients suffering from hemorrhagic diseases.
The formation of a hematoma practically nullifies the analgesic action of local anaesthetics: in fact, in the blood there are numerous active substances in the algogenic sense, which are responsible for pain, bruising or hematoma.
One of the questions that often arises is for how long and how often should TPs be infiltrated. The answer is not simple and above all it is not unique. It all depends on the clinical improvement of the patient. It can be started with one infiltration per week, but as the patient improves, the interval can be extended until the pain recurs. In some cases, pain disappears for a long time after a single infiltration; in other cases, the infiltrations must be repeated, after 2-3 days, 3-4 times.
In summary, in painful musculoskeletal pathologies it is always necessary to search for trigger points and related target areas that can be solved with banal analgesic blocks in order to avoid the patient a more painful therapeutic procedure than the pathology itself (surgery).    
A parallel can be proposed with acupuncture points. In this respect it can be said that when using needles, acupuncture is almost indistinguishable from trigger point therapy.
 
Conclusions
Myofascial pain syndrome is relevant because many disabling diseases of neck, shoulder, dorsal and lumbosacral rachis and chest are manifested with trigger points and often some of these diseases are misdiagnosed and treated for bursitis, arthritis or visceral pathologies.
Although MPS is common and not difficult to diagnose, many doctors are unaware of its existence, for a variety of reasons, including variability in the severity, duration and location of pain and the absence of a known cause. Also, unlike arthritis, where pain is limited to the affected joint or surrounding area, in MPS pain is typically felt in a region close to, but distinct from, the location of the underlying trigger points . The paucity of objective signs, radiographic negativity, and the lack of indicative laboratory tests all contribute to confusion. These factors have given rise to a number of names to define the syndrome: myositis, fibrositis , myalgia, myogelosis , myofasciitis , interstitial myofibrositis , muscle rheumatism, muscle strain, fibromyalgia.27
Much of the professional satisfaction and the physician's achievement comes from the patient's recovery. Trigger point anesthetic blockade represents one of those most successful therapeutic opportunities. Unfortunately, adequate diagnostic and therapeutic interest is not always devoted to myofascial pain. The essentially clinical diagnosis easily formulated,28 at times supported by the negative diagnostic imaging and instrumental investigations, the high frequency of cases observed, the relative simplicity of the therapy of choice and the rarity of side effects associated with the high percentage of therapeutic successes of myofascial pain syndrome one of the diseases of great interest for the anaesthetist dedicated to pain therapy.
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