Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
IIM - Epidemiology • Rare, estimated annual incidence 5-10/million, estimated prevalence ~ 60/million. • PM and DM peak in prevalence in childhood (515yrs) and mid-life (30-50yrs); IBM peaks after age 50. • Females are preferentially affected (~2-3:1) in all forms except in IBM (female:male~1:3). IIM - Epidemiology • African-Americans may be at increased risk for IIM and poorer outcomes compared to Caucasians. • All races on all continents are affected. • Anecdotal clustering of IIM onset in time and space suggest strong environmental influences. IIM – Systemic manifestations • General manifestations:fatigue, fever, weight loss. • Musculoskeletal: myalgia, muscle tenderness and weakness. Arthralgia, arthritis, contractures. • Dermatologic:Photosensitive rashes and edema. Vasculitis with infarcts and ulceration. Subcutaneous inflammation (panniculitis) and calcification. IIM – Systemic manifestations • Gastrointestinal: oropharyngeal involvement with tongue weakness and voice changes; dysphagia and reflux. • Pulmonary:Atelectasis, cough. Interstitial lung disease. Aspiration. • Cardiovascular:Tachyrhythmias and other conduction abnormalities. Congestive heart failure from myocarditis or cor pulmonale. Raynaud. IIM - Evaluation • 1. 2. 3. 4. 5. Careful history and physical examination to define: The time\tempo of symptom onset and progression. The exact nature of the problems and associated factors. Medical and family history. Muscle bulk/strength, rashes, cardiac, pulmonary, GI findings. Environmental exposures temporally associated. IIM - Evaluation • Laboratory evaluation directed by the above: 1. Muscle enzymes, serologies, tests to R/O other diseases. 2. Radiographic studies, muscle MRI. 3. EMG, biopsies of skin, muscle, possibly other tissues. 4. Special serologic or genetic studies depending upon results from the above. IIM – Laboratory abnormalities • Sarcoplasmic enzymes (CPK, LDH, ALT, AST, aldolase) – useful in assessing myositis activity. • CPK MB fraction – correlates with diseases activity and is not usually indicative of cardiac involvement unless the ratio of CK-MB/total CK rapidly increases. • ESR/CRP – elevated in <30% of pts. • ANA – positive in 60-90% of pts; best single lab discriminator of IIM from other myopathies. Causes of elevated serum CPK enzyme activity • Physical trauma or muscle stress. 1. Any muscle trauma – falls, EMG studies, surgery, muscle bipsy, IM injection. 2. Strenuous, prolonged exercise-marathon running, forced marching. • Drug effects 1. On muscle itself – clofibrate, ethanol, amphetamines, heroin. 2. On CK metabolism/clearance-phenobarbital, morphine, diazepam. Causes of elevated serum CPK enzyme activity • Diseases 1. Directly affecting muscle-non inflammatory myopathies of all kinds, MI, malignant hyperthermia, infectious myopathies, IIM. 2. Affecting blood supply to muscle-emboli to muscle, vasculitis,prolonged immobilization. 3. Affecting the CNS-cerebral ischemia, trauma,infections. • Possible familial cases in African-Americans. Myositis –specific autoantibodies (MSA) 1. Anti-synthetases – Jo 1(anti histidyl tRNA synthetase). 2. Anti-signal recognition particle (SRP). 3. Anti-Mi-2. • They are directed at conserved conformational epitopes on phosphorylated, cytoplasmic ribonucleoprotein particles involved in translation and present in all cells. MSA • They inhibit the function of the protein they target. • They appear to arise months prior to myositis onset, are antigen driven, vary in titer with myositis disease activity and occasionally become negative after prolonged remission. Associations of the MSA • Anti-synthetases (Jo1): • Arthritis, interstitial lung disease, fevers, mechanic’s hand, Raynaud’s. • Acute onset, severe disease. • Moderate response to therapy. • Prognosis poor; 70% 5-yrs survival. • Frequency in IIM 25-30%. Associations of the MSA • Anti-SRP: • Cardiac involvement, myalgias, mostly in black females. • Very acute onset, very severe disease. • Poor response to therapy. • Poor prognosis – 25% 5 yrs survival. • Frequency in IIM – 5%. Associations of the MSA • • • • • • Anti-Mi-2: Classic dermatomyositis. Acute onset. Mild disease. Good response to therapy Good prognosis. Nearly 100% 5 yrs survival/ Frequency in IIM 5-10%. IIM - pathogenesis • Polymyositis and inclusion body myositis may be more cellularly mediated (CD8+ T cells). • Dermatomyositis may be more humorally mediated (B cells). IIM – Activity evaluation 1. Muscle strength – grading: • 5 – normal power resistance. • 4 – power decreased but muscle contraction possible against resistance. • 3 – muscle contraction against gravity only. • 2 – muscle contraction possible only when gravity is eliminated. • 1 – contraction without motion. • 0 – no contraction. IIM – Activity evaluation 2. CPK levels. 3. EMG: fibrillations, positive sharp waves, short small polyphasic motor units, high frequency repetitive discharges, normal nerve conduction velocities. 4. Muscle biopsy: myofiber degeneration/regenaration, MNC infiltrates, perifascicular atrophy. IIM – Activity evaluation 4. MRI: T1-weighted images – chronic changes in muscles, atrophy. T2 – weighted and STIR images – active inflammation. • Biopsy is taken from a weak muscle, without atrophy, not damaged by EMG, injection, etc. Poor prognostic factors in Myositis • 1. 2. 3. • 1. 2. 3. 4. Based on demographic features: Age : older. Gender: female. Race: black. Based on signs-symptoms: Fever, dysphagia, severe myositis. Cardiac, pulmonary or GI involvement. Delay to diagnosis and treatment. Failure to induce remissin. Poor prognostic factors in Myositis • Based on clinical or serologic group: 1. Clinical groups: polymyositis, cancer-associated or inclusion body myositis. 2. Serologic groups: anti-synthetases or anti-SRP autoantibodies. Therapy • • • • • Steroids 1-2mg/kg/d. Cytotoxic: MTX, AZT, cytoxan IVIG Plaquenil (rash). Rehabilitation and physical therapy.