Polymyositis is a chronic inflammatory disease of the skeletal muscle. It is a predominant form of muscular dystrophy, noticed among elderly people. It is categorized as one of the three important forms of myopathies that exist. The response to this condition varies from person to person depending on the strength and dexterity of the muscle tissue. Polymyositis is generally not localized and hence many muscle groups are affected by it.
The most common muscle groups affected by this disease are the muscles associated with the neck (sternocleido mastoid), shoulders (scapular region), trapezoid region, hands and legs mainly hams and quadriceps during walking and running. The symptoms of polymyositis are usually self-limiting. However in case of adverse muscular inflammation, medical attention is required in order to prevent progressive damage of the muscle tissue.
Clinical manifestations of Polymyositis
Polymyositis has many causes - some of the common causes include infections (bacterial or viral), and inherited forms. Viral myagias are one of the forms, which can affect the muscle tissues in an intense manner if ignored. The appropriate intervention for viral Myalgia causing Polymyositis is to identify the exact cause in ruling out other infective forms such as bacterial infection through laboratory diagnosis.
Viral particles can induce the onset of fever causing muscular weakness and fatigue. Sometimes, polymyositis can affect children under these scenarios. Other generalized clinical manifestations of the disease include low-grade fever, weakness, irritability, tenderness, decreased appetite and shortness of breath. Some forms of polymyositis have long-term effects and hence such patients are advised to incorporate immunosuppressive agents. This is recommended when Polymyositis takes the autoimmune disease form.
Diagnosis of Polymyositis
Polymyositis is predominantly diagnosed by the determination of biochemical values such as creatine kinase in the blood. Creatine kinase is produced in case of muscle cell damage, the estimation of which determines the extent of muscle damage caused. Electromyograph (EMG) is also recommended to understand the neuromuscular physiology and the disorders associated with them such as myogenic condition. This is identified by the neuromuscular electrical conduction studies.
In some cases, biopsy is recommended to understand the pathophysiology of the disease through histological anomalies. The specimen is usually taken from the quadriceps or shoulders (deltoid). The pathological identification includes the presence of infiltrated muscle cells and focal regions of muscular degeneration in the muscle fibers.
Treatment of Polymyositis
Polymyositis is predominantly treated by the administration of corticosteroids in order to reduce the inflammation. These drugs can be either given by oral route or through IV administration. Other forms of treatment include immunosuppressant administration in case of autoimmune form of the disease. Azathioprine and methotexrate are generally given as immune suppressants. Appropriate intervention through corticosteroids or immune suppressants can facilitate the motor recovery in neuromuscular conduction.
Electromyography or EMG is a diagnostic test that understands the physiological of muscles thereby assessing their health. Electromyography involves inserting a needle electrode through the skin into the muscle. This electorde detects electrical activity in the muscles and nerves controlling the muscles. A patient is asked to flex or contract the muscles so that the response of the muscle to the nerve stimuli is observed. An electromyograph is used to detect and measure electric potential that is generated by the contracting muscles. Other indicators to the proper functioning of the muscles and their corresponding nerves are the size, duration and frequency of electric signals received from them. EMG is often conducted along with a nerve conduction velocity test.
The EMG test is used to diagnose any possible weakness or impaired muscle strength due to neurological problems. Some discorders that can lead to abnormal readings on EMG test are cervical spondylosis, myasthenia gravis, carpal tunnel syndrome, myopathy, Brachial plexopathy, Guillain Barre syndrome, sciatic nerve dysfunction and mononueritis multiplex. EMG test aids in differentiating between a muscle and nerve disorder. The muscle may feel tender after the EMG test with localised bruising.
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Bibliography / Reference
Collection of Pages - Last revised Date: January 30, 2023