Polymyositis

Polymyositis

Written by Dr.Yazeedallah Nasr

Polymyositis is an uncommon connective tissue disease. It is a type of inflammatory myopathy, which is characterized by muscle inflammation and weakness which occurs at any age, but it mostly affects adults sometime between their 30s and 50s. It's more common in blacks than in whites, and women are affected more often than men.

Causes:

Infections caused by bacteria, parasites or viruses, certain people may have a genetic susceptibility to the disease. Initial injury causes release of muscle auto antigen, which is subsequently taken up by macrophages and presented to CD4+ TH cells. Activated TH cells synthesize IFN-γ that stimulate further macrophages and further inflammatory mediator release like IL-1 and TNF-α.

Signs and symptoms:

Pain
Dysphagia
Difficulty of speaking
Mild joint or muscle tenderness
Sclerodactyly
Fatigue
Shortness of breath

Complications:

Aspiration and pneumonia
Breathing problems
Calcium deposits (calcinosis)
Associated conditions as Raynaud's phenomenon

Tests and diagnosis:

Imaging tests (MRI)
Muscle tests (Electromyography-Muscle biopsy).
Blood tests and blood analysis that show increase in creatine kinase and aldolase that indicates muscle damage

Treatment:

High-dose steroids are the treatment of choice
Antibody therapy
Intravenous immunoglobulin (IVIg)
Specialized exercise therapy may supplement treatment to enhance quality of life