What Is Polymyositis?

Polymyositis is an autoimmune disease with muscle weakness and myalgia as the main manifestation. The etiology is unclear. The main clinical manifestations are symmetrical symmetrical proximal limbs, weakness of the neck muscles and pharynx muscles, muscle tenderness, and increased serum enzymes. It is characterized by diffuse muscular inflammatory diseases. Most are subacute, and can occur at any age. It is more common in middle age and slightly more women. Some patients have malignant tumors before the disease, and about 20% of patients have lupus erythematosus, scleroderma, rheumatoid arthritis, Sjogren's syndrome and other autoiological diseases. The clinical manifestations of this disease are diverse due to the different ranges of involvement and associated morbidity. The disease usually peaks within a few weeks to months, and the whole body is weak. In severe cases, the respiratory muscles are weak and life-threatening.

Basic Information

English name

polymyositis

Visiting department

Division of Rheumatology

Multiple groups

Middle-aged and above

Common symptoms

Symmetrical proximal limbs, cervical muscles, pharyngeal muscle weakness, tenderness, etc.

Clinical manifestations of polymyositis

There are many infections or low fever before the disease, which is mainly manifested by the subacute to chronic progression of symmetrical proximal muscle weakness. Gradual scapular and pelvic girdle and proximal weakness of the extremities gradually appear within weeks to months. Standing in squatting position and arms Lifting difficulties is often accompanied by pain, soreness, and tenderness in the muscles and joints. Those with cervical muscle weakness have difficulty lifting their heads, and those with throat muscle weakness have difficulty swallowing and dysarthria. If the respiratory muscles are affected, they may have chest tightness and difficulty breathing. Myocardial involvement can occur in a small number of patients. The sensory disturbance of this disease is not obvious, tendon reflexes are usually not reduced, and muscle atrophy may occur within weeks to months after the disease.

About 20% of patients with PM and DM are combined with lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome, rheumatic fever and scleroderma. About 1/4 of the patients may be complicated by malignant tumors such as lung cancer. People with myositis over 40 years of age, especially those with dermatomyositis, must be highly alert to the possibility of potential malignant tumors. They should actively seek out the primary lesions. Those who cannot find the lesions for a while should be followed up regularly, sometimes it may take months to years to be found .

Polymyositis test

Peripheral white blood cell counts increased in the acute phase and normal in the stable phase. ESR can increase faster. Serum creatine kinase and lactate dehydrogenase increased significantly during disease activity. Electromyography showed that both myogenic and neurogenic lesions coexisted, and spontaneous fibrillation potentials and normal-phase spikes increased. Muscle biopsy can find pathological changes such as muscle fibrosis, necrosis, muscle atrophy and regeneration, muscle fiber interstitial inflammatory cell infiltration, small blood vessel obstruction, and capillary endothelial hyperplasia.

Diagnosis of polymyositis

Polymyositis is generally free of skin damage, with progressive muscle weakness at the proximal extremity as the main manifestation, combined with muscle enzymes, electromyography, and muscle biopsy to confirm the diagnosis. People with fever, facial erythema, especially eyelid erythema, muscle pain and weakness should consider the possibility of dermatomyositis.

Differential diagnosis of polymyositis

It needs to be distinguished from muscular dystrophy, thyroid dysfunction, and systemic lupus erythematosus.

Polymyositis treatment

General treatment

Pay attention to rest and proper physical therapy.

2. Drug treatment

Glucocorticoid treatment can suppress the inflammatory response and improve symptoms. When the body temperature is normal, muscle strength is increased, and muscle enzymes return to normal, gradually decrease. Immunosuppressive agents can be given to those who do not respond to hormone therapy. In severe cases, intravenous gamma globulin or plasma exchange therapy can also be used. In patients with malignant tumors, after the tumor is removed, the symptoms of muscle inflammation can be relieved naturally.