Myositis - causes, symptoms, diagnosis and treatment

29.01.2021

Myositis is inflammation of the muscles, accompanied by local pain during movement or palpation. Trying to protect the affected area on its own, the body increases muscle tension, which limits joint mobility, and subsequently weakness and atrophy of the damaged muscle may develop.

Muscle inflammation does not stop at one location or cause. Myositis often occurs as a consequence of infectious and autoimmune diseases. The course of the disease can be either acute or chronic, with skin rashes. With local infection, there is a high probability of development of purulent processes in the muscles.

Every person suffers from myositis at least once in their life. But in most cases, the disease remains undiagnosed, because the patients themselves define the pain as an exacerbation of osteochondrosis of the cervical or thoracic regions. Severe forms of myositis require long-term treatment and hospitalization, so you should not turn to self-diagnosis and self-medication for myositis.

Causes

Viral infectious diseases are a common cause of muscle inflammation. For example, influenza or ARVI. Myositis can occur against the background of a bacterial or fungal infection. In this case, the inflammatory process begins to develop as a result of the activity of microorganisms and their metabolic products.

More rare causes of myositis include:

autoimmune diseases: accompanied by myositis of the most severe form;
systemic diseases: accompanied by myositis of moderate severity;
parasitic infections;
exposure to toxic substances (alcohol, cocaine);
taking medications: the lesion is not always accompanied by inflammation and can be attributed to both myositis and myopathy;
hypothermia;
injury;
excessive loads during sports with poorly trained muscles;
uncomfortable body position and prolonged stress on the same muscle group due to professional activities (pianist, violinist, PC operator, driver, etc.);
open injury;
chronic infection or infection as a result of violation of sanitary standards when administering an intramuscular injection.

Treatment

Treatment for myositis depends on the cause of the disease.

The inflammatory (autoimmune) diseases that cause myositis often require treatment with drugs that suppress the immune system, including:

Prednisone
Imuran
Methotrexate

Myositis caused by an infection, usually viral, does not require treatment. Myositis caused by bacteria is not common and requires treatment with antibiotics (up to intravenous administration in order to avoid a dangerous condition for the body such as sepsis).

Although acute necrosis of skeletal muscle is rare with myositis, if rhabdomyolysis is present, it is necessary to hospitalize the patient because large fluid infusions must be administered to prevent kidney damage.

Drug-related myositis is treated by stopping the medications. In cases of myositis caused by statin drugs, muscle inflammation decreases within a few weeks of stopping the drug.

Classification

Myositis has several forms:

infectious non-purulent myositis: causes general weakness and severe muscle pain. The prerequisites are infectious diseases such as syphilis, tuberculosis, brucellosis, influenza and enteroviral diseases;
acute purulent myositis: the affected area has swelling and severe pain, necrosis develops in the muscle tissue and pus accumulates. The prerequisites are a chronic purulent process, for which myositis is a manifestation of a complication. High body temperature, leukocytosis and chills may occur;
myositis due to parasitic infections: the muscles are tense and react painfully, the affected area is swollen. This form of myositis is a consequence of toxic-allergic reactions with characteristic symptoms: malaise, fever, leukocytosis;
myositis ossificans: affected areas - shoulders, hips, buttocks. It occurs as a congenital pathology and as a result of trauma. A feature of the form is the accumulation of calcium salts in muscle tissue, which causes the formation of calcifications and compactions. The development of such myositis is fraught with muscle atrophy;
polymyositis: one of the severe forms in which a group of muscles is simultaneously affected. The cause of the development of pathology is autoimmune diseases. Polymyositis is especially dangerous for children, as blood vessels, heart, lungs, and skin can be affected. For men over 40 years of age, polymyositis can cause the development of tumors of internal organs;
Dermatomyositis (Wagner's disease): The disease affects both skeletal and smooth muscles, including the skin and internal organs.

Myositis has a large number of varieties and an equally diverse list of causes.

Diagnostics

A doctor may suspect myositis based on symptoms such as muscle weakness, pain, and other symptoms consistent with myositis. The following are used in the diagnosis of myositis:

Blood tests. Elevated levels of muscle tissue enzymes (eg, creatine kinase) may indicate muscle tissue damage. Autoantibody tests can identify autoimmune disease.

Magnetic resonance imaging (MRI). A scan using a powerful magnet and a computer produces images of the muscles. MRI analysis helps identify areas of muscle damage currently and over time.

Electromyography (EMG). By inserting needle electrodes into the muscles, the doctor can test how the muscles respond to electrical stimulators and nerve impulses. EMG allows you to identify muscles that are weak or damaged by myositis.

Muscle biopsy. This is the most accurate analysis for diagnosing myositis . The doctor identifies the weak muscle, makes a small incision, and removes a small piece of muscle tissue to examine the tissue under a microscope. A muscle biopsy provides a definitive diagnosis of myositis .

There are many causes of muscle weakness and muscle pain more common than myositis. And therefore, the diagnosis of myositis may not be made immediately, but after some time.

Symptoms

Despite the variety of forms and causes of myositis, there are symptoms that clearly indicate the development of the disease. The presence of myositis can be judged if:

aching pain is felt in the muscles, which intensifies with palpation and movement;
in some cases, swelling and redness appear in the affected area;
elevated body temperature, which lasts for a long time and is accompanied by chills, headache and an increased number of leukocytes in clinical analysis (this indicates inflammatory processes);
in some cases, compactions form that can be easily felt.

The course of myositis can develop in both acute and chronic forms. Moreover, in the absence or incorrect treatment, it can easily change one for another.

Acute myositis develops when:

hypothermia;
muscle overstrain;
injury.

Infectious and toxic myositis does not manifest itself with clear symptoms at the beginning and proceeds in a chronic form until favorable circumstances.

Chronic myositis develops along a curve, periodically subsiding and resuming. The appearance of pain is influenced by weather, low temperatures, and prolonged stress in a sedentary position.

Types of myositis

In clinical practice, the following types of myositis are most often encountered:

Cervical myositis. The most common option. The main manifestation is a dull pain in the neck muscles, most often one-sided. Sometimes it can radiate to the ear, back of the head, temple or interscapular area. Head movement is often limited due to pain.
Lumbar myositis. The key symptom is a dull pain in the lower back that can radiate down the leg. It intensifies when bending the body, pressing on the muscles of the lower back.
The most common cases are cervical and lumbar myositis. Photo: starast/Depositphotos
Dermatomyositis. Manifested by weakness of the muscles of the shoulder and pelvic girdle, as well as the abs and neck. Because of this, patients have difficulty when trying to get up from a sitting or lying position, or climbing stairs. In severe forms of the disease, breathing and swallowing are impaired. In this case, the pain is less pronounced. Dermatomyositis also affects the skin, which is manifested by a heliotrope rash (red rashes on the eyelids, less often on the face, neck and torso) and Gottron's sign (pink or reddish scaly plaques and nodules on the extensor surfaces of the elbows and knees). Additionally, disturbances in the functioning of the lungs and heart may occur.

Myositis in pregnant women

In some cases, the triggering factor for the development of myositis or the aggravation of its course is pregnancy. The most common triggers are:

Effect of the hormone relaxin on skeletal muscles.
A shift in the center of gravity and additional stress on the abdominal muscles and lower extremities.
Exacerbation of previously existing pathologies in connection with pregnancy.

Clinical manifestations of myositis during pregnancy are no different from the symptoms of the disease in other categories of patients. However, during treatment, you need to choose the right medications, avoiding drugs with a teratogenic effect. Therefore, treatment tactics must be coordinated with the attending physician.

Prevention of myositis

Prevention of myositis is based on eliminating or minimizing trigger and risk factors. The following tips and tricks can help prevent the development of muscle inflammation:

Maintain adequate physical activity.
Sports should be regulated. Before intense exercise, a warm-up must be carried out. It is recommended to use protective sports equipment (belts, knee pads, etc.).
Stop using tobacco products, drugs, and alcoholic beverages.
Avoid hypothermia and drafts.
Eat a balanced, nutritious diet.
Observe hygiene rules.
Treat existing diseases in a timely manner.

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Belikov Alexander Valerievich

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How does the disease manifest itself?

In primary forms, the first signs of the disease usually appear in childhood or adolescence. A typical symptom that may indicate the disease in a child is muscle weakness. This feature is characteristic of all forms. Weakness is usually symmetrical, meaning it occurs in symmetrical muscles. In the initial stages, weakness may be insignificant, but gradually its severity increases.

As the disease progresses, the quality of life decreases: even habitual loads become difficult and difficult for the patient to perform. Difficulties appear when walking or climbing stairs. Due to muscle dystrophy, posture may be disrupted and curvature of the spine may appear, for example, lumbar lordosis, kyphosis, scoliosis, which progress over time. In this case, the patient’s head and stomach protrude forward, the shoulders drop, and wing-shaped shoulder blades are formed3.

When the proximal muscles, located closer to the center of the body, are affected, difficulties arise with rising from a chair, getting out of the bath, climbing stairs, combing hair, or shaving. A “duck” gait is observed - the patient moves, swaying to the sides. With weakness in the hands, a person has difficulties performing highly differentiated work (writing, playing musical instruments, turning, etc.). Weakness of the feet is manifested by the formation of a hollow foot, a flopping gait. In some forms, for example, Nemalin myopathy, sometimes with Pompe disease, weakness of the respiratory muscles appears, which leads to an increased risk of pulmonary infections. In addition, the oxygen supply deteriorates, which can cause damage to the brain, heart, and other organs4.

Along with muscle weakness, tendon reflexes decrease, muscle spasms or contractions occur, and joint mobility is limited—contracture3.

Complications of myositis

Potential complications of muscle inflammation depend on the etiology of the disease. The most likely ones include:

Spread of the purulent process to adjacent tissues with the formation of osteomyelitis, abscesses and phlegmons, purulent arthritis.
Limitation of physical capabilities, contractures and muscle atrophy.
Impaired swallowing and breathing, which leads to respiratory failure and the risk of developing aspiration pneumonia.
Rhabdomyolysis is the melting of muscle tissue with breakdown products entering the systemic circulation. In this case, renal failure and sepsis can develop, which often lead to death.