The fascial system consists of solid (muscles, bone, cartilage, and adipose tissue) and liquid (blood, lymph) components. The myofascial system comprises contractile muscle 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, thereby transmitting movement from the muscles to the bones to which they are attached. Within the myofascial system, the other components include the nervous, vascular, and lymphatic system. Nervous tissue (axon and various afferents) and the resulting terminations are enclosed in multiple layers of fascia. Different tissues work in harmony to make up the myofascial continuum. The fascia integrates all the muscles contained within into an interconnected network and it would be incorrect to consider a muscular district as a separate entity.
The myofascial system, if disturbed can be a source of pain and functional limitation by creating vague symptoms that are not always clear and a challenge for the treating physician. The article reviews myofascial pain or myofascial syndrome, highlighting the latest news and current scientific updates. Myofascial pain is characterized by the presence of muscular trigger points (TP) which are hard, palpable nodules located within the taut bands of skeletal muscle. They are tender to palpation and movement, causing local and referred pain. There are two types of trigger points: active and latent. Active trigger points are associated with pain without movement or palpation, and latent trigger points which are painful only to palpation.
Myofascial pain syndrome is a disease with no standard management and surveillance protocol. The previous term to describe a TP was "fibrositis," (inflammation of the connective tissue that covers the muscles). Myofascial trigger points are nodules in muscles, that are tender to pressure and movement. TPs cause weakness of the muscle, as well as a limitation in the range of motion. Multiple TPs persistent for not less than a year confirms myofascial pain syndrome.
Myofascial pain was first described by Guillaume de Baillou in 1600. In 1816, Balfour further described this pain to be associated with "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 painful nodules. In 1919, Schade proposed the term "myogeloses" to describe the hard texture of the TP. In the mid-1900s, some scientists identified painful local areas in patients with myofascial pain which, that when stimulated (hypertonic saline), produce pain. Janet Travell was inspired by these studies, and together with Rinzler coined the term "myofascial trigger points."
When considering the etiology of myofascial pain, one must remember that myofascial compartment is also constituted by the soft tissue that transports fluids (blood and lymph) and action potentials (afferent and efferent nerves). Vascular and nerve pathways can be a source of pain because they are innervated. The liquid fascia (blood and lymph) can be a source of pain, because changes in flow velocity, direction, and type of flow, can affect surrounding tissues, thereby leading to myofascial pain.
The cause of myofascial pain is not fully understood. It may be due to one or more of the hypothesized causes given below:
The prevalence of myofascial pain syndrome in the United States is about 9 million, and it is estimated that the same percentage of patients is found in Canada. Myofascial pain syndrome affects men and women equally, while it is more prevalent in people greater than 6o years of age. There is no convincing data to suggest a relationship between myofascial pain and ethnicity or geographical location.
In order to understand and treat myofascial pain, it is important to know the pathological processes behind this syndrome. The myofascial trigger point is a site of latent ischemia, which could explain the cause of pain. This ischemia lowers the pH, creating an acidic environment in the myofascial compartment. This decreases the amount of acetylcholinesterase (AChE), while it increases the effectiveness of acetylcholine (ACh), hence causing prolonged muscle contraction. In this altered environment, the release of nociceptive substances such as calcitonin gene-related peptide (CGRP) results in the increased number of ACh receptors and ACh release, while decreasing the effectiveness of AChE. 
The amount of ATP within a TP is decreased. Ischemia causes decreased ATP leading to a lack of muscle relaxation (ATP depletion prevents the calcium pump - Calcium ATPase) to withdraw the calcium present in the muscle fibers. This leads to calcium (Ca2+) accumulation within the myocytes. If calcium is not withdrawn completely from the cytoplasm, it becomes cytotoxic, stimulating inflammatory mediators like bradykinin, CGRP, tumor necrosis factor-alpha, substance P, inflammatory interleukins (IL-6, IL-8, IL-1beta), norepinephrine, and serotonin. Such inflammatory substances cause increased nociceptive sensitization that results in severe pain.
According to a recent theory, TPs may derive nociceptive afferents via the subcutaneous accessory pain system (SAPS), which as an extra-innervation pathway to the spinal cord through the dorsal rami. Another theory states that myofascial pain could be due to dysfunction of spinal and supraspinal pathways. Cutaneous Silent Period (CSP) is defined as a brief interruption in voluntary action, after strong sensory stimulation. It is useful for evaluating features of the sensory nervous system that are poorly assessed by other electrodiagnostic studies, as well as the spinal and supraspinal pathways. Abnormal CSP parameters in patients with Myofascial pain may suggest a problem with spinal or supraspinal pathways. A 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.
Nociceptive afferent signals from the myofascial system could cause structural and functional changes of the central nervous system (CNS), starting from the spinal cord (due to an accumulation of inflammatory substances), causing changes in medullary neurons (increase in neuronal excitability) with centrifugal progression. This mechanism would provoke central sensitization with a lack of inhibition of the descending pain inhibitory pathways, perpetuating inflammation and the formation of TPs.
Myocytes in TPs are non-uniformly distributed, rounded in the middle and thinner at the periphery with a reduced number of mitochondria and accumulation of inflammatory cells. The thickness of the Z line of sarcomeres is smaller, with a wider band A and with the absence of band I. These muscle cells are less elastic with damage to proteins such as desmin, titin, and nebulin, and reduced volume of capillaries.
Erythrocytes in patients with myofascial pain show a lack of antioxidants, such as selenium and zinc. This causes greater oxidative stress that would stimulate a systemic inflammatory response, but further studies are necessary to draw definitive conclusions.
Myofascial pain syndrome comprises both acute and chronic pain. The pain experienced in this syndrome is usually dull aching and poorly localized indistinguishable from other causes of somatic and visceral pain. Sensory paresthesias or dysesthesias may accompany myofascial pain occasionally. Sometimes, the pain produced by this condition can be felt at a point away from the actual disease process. It may persist many months or years after the insult was caused, even if the initiating event is resolved. Constricting myofascial taut bands may cause entrapment of nervous component of the myofascial system, leading to further pain and disability.
Myofascial pain syndrome is diagnosed by the presence of myofascial trigger points and associated pain. Myofascial trigger points are located by palpation of the tender or painful areas of the patient. A trigger point is defined by the presence of a tight band which is palpable within the muscle tissue, which through practice and experience can be palpated easily usually in all types of muscles either a superficial or deep. Such muscles that contain trigger points are non-uniform having heterogeneous areas consisting of soft, firm, or hard consistency rather than uniform homogeneous consistency. On contraction of the trigger points during daily activity pain is usually experienced by the patient which is exquisite and localized. Sometimes taut bands are not painful to palpation but can alter the normal sequence of muscle activation. The correct method of palpation of the trigger points consists of palpating the muscle perpendicular to the direction of the muscle fibers.
A delphi study conducted in 2017 proposed that at least two of the following criteria must be positive for trigger point diagnosis: presence of a taut band, a hypersensitive spot, and referred pain. The pain referred from a myofascial trigger point causes different sensory sensations that include pain traveling to a distant area, deep pain, dull aching, tingling, or burning pain. 
Several diagnostic tools are available to assess the presence of trigger points with individual advantages.
Exercise/Physical therapy/Postural regiments
Osteopathic Manipulative Therapy (OMT)
Myofascial pain syndrome usually resolves with consistent treatment and regular follow-up. However, a majority of patients with this condition suffer from this problem for decades. Long term morbidity is least when a multidisciplinary team consisting of well-trained physicians, nurses, and physiotherapists treat such patients and constantly monitor the response to various therapies employed.
Myofascial pain syndrome can cause a reduction in the quality of life. Long term pain is usually associated with mood disorders (depression and anxiety). It can decrease in the mobility of the patient, decreasing daily activity which further precipitates the condition.
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.
Upon identification of the cause of myofascial pain, it is necessary to explain to the patient the relevant pathophysiology and the ways of improving the quality of life. 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 of 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 pain, 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.
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