Inflammatory myopathies
Inflammatory myopathies are a heterogeneous group of rare acquired muscle diseases. It is characterized by the presence of an inflammatory process in skeletal (striated) muscles, as a result of which degenerative changes occur. In inflammatory myopathies, inflammation is autoimmune or infectious in nature. This type of myopathy is accompanied by:
muscle weakness;
muscle aches;
atrophy;
the presence of contractures;
decreased motor activity;
the appearance of muscle swelling;
in some cases, muscle compaction is observed.
The content of the article:
Causes of inflammatory myopathy
Symptoms of inflammatory myopathy
Diagnosis of inflammatory myopathy
Treatment of inflammatory myopathy
Inflammatory myopathies
Inflammatory myopathies are a large group of diseases that include systemic lesions of muscle tissue (dermatomyositis, polymyositis, eosinophilic myositis, myositis with inclusions, rheumatic polymyalgia), as well as local inflammation in certain muscle groups (ocular muscle myositis, pseudothrombophlebitis of the lower leg muscles, etc.).
The age of people when the risk of infection with inflammatory myopathies is highest depends on the type of disease. For example, polymyositis is observed more often after the age of thirty, myositis with inclusions affects people over forty years old, while being the most common form of inflammatory myopathies occurring in old age.
Causes of inflammatory myopathy
There are quite a lot of causes of inflammatory myopathies. Doctors emphasize that the ethology and pathogenesis of diseases of the presented group have not been fully studied, do not have a clear scheme.
Some infectious diseases (influenza, HIV infections, rubella, etc.) can become provocateurs of inflammatory myopathy.
Streptococcal bacteria, parasitic infestations such as toxoplasmosis or trichinosis, as well as fungal infections can also be the causes of inflammatory myopathies.
There are also idiopathic myopathies (diseases whose excitation is not associated with infections), they have an autoimmune mechanism of development, but it should be said that the antigen that underlies the excitation of an autoimmune reaction has not been calculated. When studying the disease, family cases were identified, based on which it is possible to judge the genetic nature of this group of diseases.
Idiopathic inflammatory myopathies include: polymyositis, myositis with inclusions, myopathies in systemic diseases (systemic lupus erythematosus, scleroderma, Sjogren’s syndrome, rheumatoid arthritis, systemic vasculitis). Patients with dermatomyositis and polymyositis are more prone to oncological diseases, especially in the form of malignant tumors.
Symptoms of inflammatory myopathy
Inflammatory myopathies have the following symptoms:
Muscle pain syndrome (myalgia). With the progression of the disease, pain is observed not only during motor activity, but also during rest or with slight pressure on the muscles.
Muscle weakness. A person has difficulty squeezing objects in his hands. Progressing, the disease makes it almost impossible to raise an arm or leg, deprives the patient of the opportunity to sit down and get up on his own.
A significant reduction in the volume of active movements, and in some cases the patient is bedridden.
Swelling and compaction of the affected muscles.
The development of atrophy and myofibrosis (muscle fibers are replaced by connective tissue).
Calcification.
Contractures.
Joint stiffness.
Myopathic laryngeal paresis.
Respiratory failure.
Stagnant and aspiration pneumonia (occur as a result of weakness of the respiratory muscles and decreased pulmonary ventilation).
The clinical picture of diseases from the group of inflammatory myopathies is different, as is the duration of the course. With dermatomyositis, for example, symptoms begin to manifest themselves in the form of general malaise and fever, fever. Subsequently, there is a characteristic rash on the skin, and then weakness of the proximal muscles. A purple rash can be observed on the surfaces of the eyelids, accompanied by swelling and telangiectasia on the neck and chest, between the phalanges of the fingers and on the hand — erythematous rash. Thickening of the skin appears on the joints of the knees and elbows. With dermatomyositis, there is hyperemia of the cheeks, discoloration and thickening of the nail beds, which leads to swelling of the fingers. Further, progressing, the disease leads to muscle stiffness and pain syndrome. Damage occurs mainly to the proximal muscles, distal muscles are less susceptible to injury.
In children, the disease can manifest itself as an acute attack or an alternation of exacerbations and remissions. With rapid progression, respiratory failure may occur, since the larynx and respiratory tract muscles are affected. Calcifications in subcutaneous tissues were detected in more than half of infected children. In some cases, the disease ends fatally (about 10% of all infected children).
In almost half of adult patients, malignant tumors are detected during the diagnosis of dermatomyositis (for comparison, tumors are observed very rarely in patients with polymyositis). As a result, the symptoms of oncological education are superimposed on the clinical picture of dermatomyositis, which significantly complicates the diagnosis and treatment of the disease. When a malignant tumor is removed, muscle weakness regresses. The true cause of malignant neoplasms in the clinical picture of dermatomyositis remains unknown.
Diagnosis of inflammatory myopathy
Diagnosis of inflammatory myopathies is difficult. This is due to the wide spread of the clinical picture. The symptoms are very similar to diseases that belong to the group of inflammatory myopathies, as well as diseases of a different nature. In the process of diagnosis, it is necessary, first of all, to differentiate the disease among homogeneous ones. The patient should undergo consultations with a neurologist, dermatologist, pulmonologist and cardiologist to obtain the most accurate clinical picture and exclude similar diseases.
In most inflammatory myopathies (except for myositis with inclusions), there may be an increase in ESR in the blood, but almost half of this indicator shows the norm. An important indicator in the diagnosis of this disease will be the CPK (creatine phosphokinase level), which can be used to judge the degree of damage to the muscles and muscle membrane. It is often possible to observe an increase in the level of the CK isoenzyme. The concentration of myoglobin in the serum also increases and indicates a clear progression of the disease and the appointment of adequate treatment.
When diagnosing this disease, EMG is also prescribed, the results of which are important for diagnosis. With polymyositis and dermatomyositis, short-term polyphase potentials of motor units are usually observed (this applies to the proximal muscles). Similar changes can also be observed in myositis with inclusions. In addition, similar anomalies can be detected during EMG and in neurogenic lesions. Therefore, it is impossible to establish an accurate diagnosis relying only on EMG. A muscle biopsy is also performed. This analysis helps to determine the prevalence of the inflammatory process.
A hormonal study is carried out in the absence of a rash. The purpose of this study will be to determine the content of triiodothyronine, thyroid-stimulating hormone TSH and thyroxine.
Treatment of inflammatory myopathy
There is no pathogenic or etiological treatment. Treatment is mainly aimed at eliminating symptoms and general maintenance of muscle strength, eliminating contractures, as well as achieving drug remission.
Despite the limited amount of information about the treatment of these diseases, doctors have come to a consensus — immunosuppressive therapy gives good results. Most often, the patient is assigned a whole range of measures. Firstly, it is a medical therapeutic treatment. One of the most successful and effective methods is glucocorticoid therapy (prednisone and metipred). The dose of drugs is 1 mg per 1 kg of weight. Take medications strictly every other day to avoid complications that may occur due to the use of glucocorticoid therapy. When prescribing such therapy, the doctor should carefully examine the patient for the presence of concomitant diseases that can cause complications. Such diseases in which glucocorticoid therapy is contraindicated include:
diabetes mellitus;
osteoporosis;
stomach ulcer;
obesity or any other metabolic disorders;
high blood pressure.
Remission occurs in about one to two months. After that, the dose of drugs decreases under the strict control of needle EMG. Sometimes the attending physician decides to replace the base drug, subject to significant improvements in the analysis of the clinical picture. Most often, azathioprine acts as a substitute drug. If glucocorticoid therapy did not give the desired results, then cytostatic therapy is prescribed in parallel to enhance the effect.
For a speedy remission, doctors also advise physical therapy (strictly under the supervision of a physical therapy therapist or a competent specialist), a course of massages, various orthopedic measures. Doctors recommend active movement, prolonged lying is contraindicated. Premature use of a wheelchair is also not recommended, since it provides for the rest of a significant part of the muscles.
Speaking about the prognoses of this group of diseases, they are not bad. With timely and adequate treatment, about half of the patients significantly improve their general condition and are completely cured. A third of patients are left with a feeling of muscle weakness. During the first three to four years, approximately 15% of patients with severe form die from concomitant diseases of the heart, lungs, etc. A significant part of deaths occur due to the formed oncological tumors.
