Dermatomyositis / Polymyositis
Polymyositis / Dermatomyositis is autoimmune disease with Inflammatory directed to muscle. Cause is unknown and can affect individuals of all ages. The annual incidence of polymyositis and dermatomyositis ranges from 5–10 new cases per million. The average female-to-male ratio exceeds 2:1, with women predominating in this disease that occurs characteristically between ages 15 and 44 years.
The idiopathic inflammatory myopathies are immune-mediated processes, believed to be triggered by environmental factors in genetically susceptible individuals. The specific causes or triggering events remain unknown, but viruses have been strongly implicated.
Frequently Asked Questions
How is Polymyositis diagnosed?
Patient present with symmetrical weakness typically affecting proximal Limd girdle muscles. Muscle biopsy shows evidence of inflammation, blood tests show elevated muscle enzyme markers and nerve conduction studies show low amplitude motor unit potentials, fibrillation potentials and bizarre- frequency repetitive changes. Skin shows periorbital rash called heliotrope rash and scaly erythematous eruptions on the fingers around the small joints called gottron’s sign.
How is Polymyositis/ Dermatomyositis treated?
Treatment of inflammatory myopathies is largely empirical. Physical therapy plays an important role. However, bed rest may be required during intervals of severe inflammation. Corticosteroids are the standard first line medication for any inflammatory myopathy. If a patient does not respond to corticosteroids, another disease modifying agent is tried and in severe cases infusion therapies help. Clinical improvement may be noted in the first weeks or gradually, over three to six months.