What are the symptoms and causes of viral myositis

Viral myositis is also called acute benign myositis in children. It is a myositis that occurs in children during the course of influenza. The incidence of this disease is very high in spring and winter. Among them, the symptoms of viral myositis are relatively obvious, and patients may experience symptoms of upper respiratory tract infection such as runny nose and fever.

1. Symptoms

The children were all in good health. At the beginning of the disease, they all had symptoms of upper respiratory tract infection such as fever, runny nose, nasal congestion, and paroxysmal cough. The course of the disease was 3 to 7 days, or there was diarrhea. The children suddenly developed pain in both calf muscles when they woke up in the morning. The myalgia was mainly in the calf muscles, more on both sides than on one side, and secondly in the thigh muscles. It could occasionally affect the neck, scapula, and upper limbs. The myalgia was mostly dull pain, often occurring after exercise and relieved after rest. They had difficulty walking or refused to walk. Physical examination showed tenderness in both calf muscles, but no skin sensory abnormalities, no redness or swelling in appearance, and negative neurological pathological signs. After treatment, the myalgia recovered quickly and disappeared rapidly. The symptom relief time in this group was 2 to 4 days.

2. Reasons

Viral infection: Acute benign myositis in children was first discovered by Lundbeng in 1957 in Swiss children. The disease may be a viral infection, such as Coxsackie virus, influenza A or B virus, and parainfluenza virus type 1 and 3, especially influenza B virus infection. In recent years, it has been reported to be related to Epstein-Barr virus, HIV virus, etc. Foreign literature reports that the infection rates of influenza A and B viruses in BACM are 5.5% and 33.9, respectively.

Low immunity: Children’s immunity is not fully developed due to their body development, so they are susceptible to infection in susceptible environments. Patients with certain immune system diseases are also susceptible.

3. Laboratory examination

Peripheral blood leukocytes were all within the normal range, and peripheral blood images showed mainly increased lymphocytes. Serum creatine phosphokinase (CPK) was high, ranging from 394 u/L to 2 759 u/L. Lactate dehydrogenase (LDH), creatine kinase isoenzyme (LK-MB), and α-hydroxybutyrate dehydrogenase (HBDH) were also slightly increased, but the increase in CK was most obvious.