What kind of disease is myositis

Myositis, also known as polymyositis, has an autoimmune disease whose cause is not very clear. After suffering from myositis, symptoms such as pain, soreness and tenderness in the muscles and joints will appear. In severe cases, there will also be difficulty swallowing, chest tightness and breathing. It is very harmful. We must have a full understanding of this disease so that we can better treat it. So, what is myositis? Let’s take a look below.

Polymyositis is an autoimmune disease with muscle weakness and myalgia as its main manifestations. The cause is unclear. The main clinical manifestations are diffuse muscle inflammatory diseases characterized by symmetrical proximal limb, neck and pharyngeal muscle weakness, muscle tenderness, and increased serum enzymes. Most cases have a subacute onset and can occur at any age, but are more common in middle-aged people and slightly more common in women. Some patients had malignant tumors before the onset of the disease, and about 20% of patients had other autologous diseases such as lupus erythematosus, scleroderma, rheumatoid arthritis, and Sjögren's syndrome. Due to the different scope of involvement and the great differences in concomitant diseases, the clinical manifestations of this disease are diverse. Usually the disease reaches its peak within weeks to months, with general muscle weakness and in severe cases respiratory muscle weakness, which is life-threatening.

Therefore, early diagnosis and treatment are very important. As long as hormone or immunosuppressant treatment is used in time, simple polymyositis can be expected to have a good prognosis, while the prognosis is poor for patients with concomitant malignant tumors and various connective tissue diseases.

Clinical manifestations

There is often infection or low fever before the onset of the disease, and the main manifestations are subacute to chronic progressive symmetrical proximal muscle weakness. Within weeks to months, weakness of the shoulder girdle, pelvic girdle and proximal limbs gradually appears, and it is difficult to stand from a squatting position and raise the arms, often accompanied by pain, soreness and tenderness in the muscles and joints. People with weak neck muscles have difficulty raising their heads, while people with weak throat muscles experience difficulty swallowing and dysarthria. If the respiratory muscles are affected, there may be chest tightness and difficulty breathing. Myocardial involvement may 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 several weeks to months after the onset of the disease.

About 20% of PM and DM patients have concurrent diseases such as lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, rheumatic fever and scleroderma, and about 1/4 of patients may have concurrent malignant tumors such as lung cancer. People over 40 years old who develop myositis, especially dermatomyositis, must be highly alert to the possibility of potential malignant tumors and should actively look for the primary lesion. If the lesion cannot be found at the moment, regular follow-up should be performed, as it may take months to years to be discovered.

examine

The peripheral blood leukocyte count increases in the acute phase and is normal in the stable phase. Erythrocyte sedimentation rate may increase. Serum creatine kinase and lactate dehydrogenase increased significantly when the disease was active. Electromyographic examination revealed the coexistence of myogenic and neurogenic lesions, with an increase in spontaneous fibrillation potentials and positive sharp waves. Muscle biopsy can reveal pathological changes such as muscle fiber degeneration, necrosis, muscle atrophy and regeneration, inflammatory cell infiltration in the muscle fiber interstitium, small blood vessel obstruction, and capillary endothelial hyperplasia.

diagnosis

Polymyositis generally has no skin lesions and is mainly manifested by progressive muscle weakness in the proximal limbs. It is confirmed by combining muscle enzymes, electromyography and muscle biopsy characteristics. Dermatomyositis should be considered in patients with fever, facial erythema, especially eyelid erythema, muscle pain, and muscle weakness.

Differential Diagnosis

It needs to be differentiated from muscular dystrophy, thyroid dysfunction, systemic lupus erythematosus, etc.

treat

1. General treatment

Pay attention to rest and appropriate physical therapy.

2. Medication

Glucocorticoid treatment can inhibit inflammatory response and improve symptoms. Gradually reduce the dosage when body temperature returns to normal, muscle strength increases, and muscle enzymes return to normal. Those who are unresponsive to hormone therapy can be given immunosuppressants. In severe cases, intravenous immunoglobulin or plasma exchange therapy can also be used. Myositis symptoms may be relieved naturally in patients with malignant tumors after tumor resection.