Polymyositis

//Western Diagnosis//
systemic ct disease with inflammatory and degenerative changes in muscles and frequently also in skin Systemic weakness and muscle atrophy of limb girdles

Etiology
- Unknown -Immune complement deposition in vessel walls of skeletal muscle -Cell-mediated imune reaction to muscle -viruses -neoplasm may incite myositis as autoimmune rx to common antigen in muscle and tumor -Less common than SLE or PSS -2x more in women -Ages 40-60 or 5-15

Signs & Symptoms
1. Acute or insidious onset 2. Often begins with acute infection 3. Initial symptoms: -Proximal muscle weakness -Muscle pain -Rash -Polyarthralgias -Raynaud's -Dysphagia -Fever, fatigue, weight loss 4. Muscular -Weakness: sudden onset, progressive over weeks to months. Shulder & pelvic girdles. Difficulty raising arms over shoulders, climbing stairs, arising from sitting, raising head from pillows. Neck flexors -Laryngeal - dysphonia -Pharynx, esophagus - dysphagia, regurgitation -Lower esophageal dilation - like PSS -SI dilation - like PSS -Hands, feet, face not involved -Polyarthralgias in 1/3 of cases -Raynaud's - esp. if also other ct disease 5. Dermatological -Dusky, erythematous, butterfly-like SLE -Periorbital edema with heliotrope hue (blue purple) is pathognomonic -Rash elevated, smooth & scaly: fade and then brown, atrophy, scarring, vitiligo. Tenderness, induration with rash -Calcinosis 6. Visceral -less common than in other ct diseases -Pneumonitis: dyspnea, cough -Cardiac electric disturbances -Renal failure -GI ulceration -Malignancy in ~15% of cases with no common site

Lab Testing
1. nonspecific 2. Sed rate is elevated 3. muscle enzymes elevated. CK most specific. Decrease with effective therapy, may be negative despite active disease

Diagnosis
5 major criteria -Proximal muscle weakness -characteristic skin rash -elevated muscle enzymes -muscle biopsy changes -electromyographic abnormal 2. Always consider malignancy

Prognosis
1. Long remissions reported 2. More resistant and severe with cardiovascular and plmonary involvement 3. death follows severe muscle weakness, dysphagia, malnutrition, neumonia, respiratory failure

Treatment
1. Decrease activity until infl subsides 2. Corticosteroids 3. Immunosuppressive agents: methodrexate, cyclophosphamide, chlorambucil, azathioprine