The myofascial system comprises contractile muscle tissue and connective tissue. The latter creates the shape of the muscle, penetrates the muscle and orients the nerve and vascular endings; it's thickening at the end of the contractile district forms the insertions and origins of the muscle on the bone tissue, transmitting the movement from the muscles to the bones to which they are attached. Within the myofascial system, there are other fascial organizations, such as the nervous and vascular tissue and the lymphatic system. Nervous tissue (axon and various afferents) and the resulting terminations are fasciae.
Different tissues work in harmony to make up the myofascial continuum. Thanks to the fascial tissue, all the muscles make up a network in constant connection, and it becomes an error to consider a muscular district as a separate entity. It is impossible to intervene or come in contact with a muscle excluding the associated connective or fascia tissues.
The myofascial system can be a source of pain and functional limitations by creating symptomatic pictures that are not always clear and not always easy to frame. The article reviews myofascial pain or myofascial syndrome, highlighting the latest news and current scientific information.
The pain of the myofascial system derives from the presence of muscular trigger points, of the well-localized areas of taut band, which at the palpation or to the active movement generate local pain or referred pain. There are active trigger points, painful areas to movement or painful even in the absence of movement, and silent trigger points, which become painful only at palpation.
When considering the reasons for myofascial pain, it should be remembered that myofascia is also constituted by the fascial organization that transports fluids (blood and lymph), the nerve pathways (axon and different afferents). Vessels and nerve pathways can be a source of pain because they are innervated. The liquid fascia can be a source of pain, because according to their speed, direction and type of flow specifically stimulate the fascias in which they pass.
The causes that lead to pain are not fully understood.
Myofascial pain syndrome involves about 9 million people in the United States; it is estimated that the same percentage of patients is found in Canada. The distribution of the presence of TPs is similar between men and women, while it is more prevalent in people aged 60 and over. There is no convincing data on the distribution of TPs based on ethnicity or geographical location.
In the presence of a TP, one can find latent ischemia. This ischemia lowers the pH, creating an acidic environment. The latter will decrease the amount of acetylcholinesterase (AChE), while it will increase the effectiveness of action of acetylcholine (ACh), allowing prolonged muscle contraction. In such an altered environment, the release of nociceptive substances such as calcitonin gene-related peptide (CGRP) is stimulated; the latter will create a loop, further stimulating the release of ACh and decreasing the effectiveness of AChE. Not only. CGRP can increase the number of receptors for ACh, implementing muscle contraction and the formation of TPs.
The amount of ATP within a TP is decreased. The lack of muscle relaxation does not allow the calcium pump (Calcium ATPase) to withdraw the calcium present in the muscle fibers, with calcium (Ca2 +) accumulation. If calcium is not withdrawn completely from the cytoplasm, it becomes cytotoxic to the contractile cell, stimulating an inflammatory environment with bradykinin, CGRP, tumor necrosis factor alpha, substance P, inflammatory interleukins (IL-6, IL-8, IL-1beta), norepinephrine and serotonin, urging the sending of painful information to the nervous system.
According to a recent theory, TPs may derive nociceptive afferents or subcutaneous accessory pain system (SAPS), which would reach the spinal cord through the dorsal branches. This theory could be confirmed by the fact that cutaneous silent period (CSP), which evaluates the cutaneous sensory system of a cutaneous nerve, presents abnormal values over the musculature where TPs reside. This suggests a dysfunction of the spinal and supraspinal pathways. The concept of altered electrical activity of the skin and the afferents coming from the TPs could explain the altered emotional state in patients with the myofascial syndrome (anxiety and depression). There is a close relationship between the epidermis (ectodermal embryological derivation) and the limbic areas of the brain in a bi-directional way. A human model study showed a reduction in the gray matter of the limbic area (thalamus, cingulate gyrus, insula, and parahippocampal gyrus), in patients with myofascial pain syndrome. This means that in the light of the data, in the presence of a patient with TPs, one must also consider the skin in the treatment of myofascial pain.
Continuous nociceptive afferents from the myofascial system could cause structural and functional changes of the central nervous system (CNS), starting from the spinal cord due to inflammatory substances, leading to changes in medullary neurons (an increase of neuronal excitability) and then changes centrally. This mechanism would provoke a central sensitization, with a lack of inhibition of the descending pathways for pain control, perpetuating inflammation and the formation of TPs.
Muscle cells in TPs appear rounded and not uniform, curved in the middle and thinner at the periphery; infiltrations of inflammatory cells are shown. There are fibers consumed and disorganized, with a reduced number of mitochondria. The thickness of the Z line of sarcomeres is thinner, with a wider band A and with the absence of band I. The muscle cell is less elastic, with damage to proteins such as desmin, titin, and nebulin; the volume of capillaries is reduced.
Blood erythrocytes in patients with TPs show a lack of antioxidant substances, such as selenium and zinc. This could mean a more constant oxidative status that would stimulate a systemic inflammatory environment, but further studies are necessary to draw definitive conclusions.
Myofascial pain is a clinical problem in which there is no standard approach for evaluation or treatment. The previous term to show TPs was "fibrositis," a term sought to describe an inflammation of the connective tissue that covered the muscle tissue. For many clinicians, the confirmation that these are trigger points is multiple painful areas in multiple muscle areas. TPs cause a general weakness of the muscle, as well as a limitation of the range of motion; a further confirmation of myofascial pain is muscular nodules for not less than 1 year.
The first who described tissue myofascial pain was Guillaume de Baillou in 1600. In 1816, Balfour added some annotations, such as "thickenings" and "nodular tumors." In 1843, Froriep described the TPs as an accumulation of painful connective tissue. In 1904, Gowers wrote that the TPs were accumulations of inflamed connective tissue responsible for creating these painful nodules. In 1919, Schade proposed the term "myogeloses" to show a high viscosity nodular muscle structure.
In the mid-1900s, some scientists identified painful local areas which, if stimulated (hypertonic saline), produced reported pain. Janet Travell was inspired by these studies, and together with Rinzler coined the term "myofascial trigger points." Later, David Simons and Travell wrote books that after more than 40 years ago and their beliefs about TPs is still clinically applicable.
Currently, the causes of the presence of TPs are only speculative, as well as the correct evaluative and therapeutic approach.
Several diagnostic tools are available to assess the presence of trigger points, but there is no agreement on the results.
Exercise/Physical therapy/Postural regiments
Osteopathic Manipulative Therapy (OMT)
The painful myofascial syndrome is difficult to identify as a primary cause in a symptomatic picture where local and reported pain exists. According to a recent study, there are no specific muscle areas where TPs always appear. Confirmation of the diagnosis of the presence of TPs should include three signs simultaneously: muscle stiffness or spasms; a limited range of motion; painful symptoms accentuated by stress and / or palpable taut band areas. The symptoms must have been present for at least 3 months. It is better if, in addition to the palpation, some instrumental investigation is combined, with ultrasound. Once the TPs are localized, they should be palpated again, because the contracted muscular areas do not move, to confirm the stable presence of these nodules.
Generally, if the patient is diagnosed appropriately and follows the indications of specialized personnel, the correlated symptoms decrease considerably, and pain diminishes.
Undesirable effects of drug therapies may occur if the patient does not follow the doctor's instructions carefully. Similarly, if the approach to physical activity does not follow certain rules set by competent personnel, muscle trauma may occur.
If the causes are identified, it is necessary to explain to the patient that the motivations that led to myofascial syndrome must be changed. For example, if the patient is anxious at work or during daily activities, they require strategies to relax, perhaps with deep breathing or the learning other relaxation techniques with the help of a psychologist. If the pain is from a poor diet, it is necessary to teach the patient to consume a more balanced diet. If repetitive movements cause the presence of TPs, encourage the patient to perform physical activity, including stretching. A sleep disorder may lead to increased muscle tension, resulting in the formation of TPs. In this case, it is necessary to adopt strategies to improve the quality of sleep.
In diagnosing and treating myofascial syndrome, many professionals should interact for the patient's health. The doctor or nurse practitioner make the diagnosis, and based on the etiology, the patient will be directed to specialists, for example, the physiotherapist, the osteopath, the psychologist, and the nutritionist. It will be an interprofessional team that treats the patient because the patient needs physical, psychological, and nutritional support. Pharmacists should be included as part of the team to assure that no drug-drug interactions occur involving pain management. The clinician should not only examine painful areas but all aspects of the patient's health.