Yuliarni SyafritaBagian Neurolog

FK Unand

Polymyositis is an idiopathic inflammatory myopathy

causes symmetrical, proximal muscle weakness

elevated skeletal muscle enzyme levels

General◦ group of disorders◦ proximal muscle weakness◦ nonsuppurative inflammation skeletal muscle◦ prevalence

5 cases/mil/year 2 to 1 F>M 40-60 yrs pediatric variant 5-15-yrs

Epidemiology Idiopathic inflammatory myopathies are

relatively rare diseases. incidence in the United States that ranges

from 0.5-8.4 cases per million population. more common in the US within the black

population, with the estimated black-to-white incidences for polymyositis and dermatomyositis being 5:1 and 3:1, respectively.

Internationally, polymyositis is less common among Japanese persons.

usually affects adults older than 20 years, especially those aged 45-60 years.

Polymyositis rarely affects children. observed in children, usually those aged 5-

14 years In most patients, polymyositis responds well

to treatment, although residual weakness occurs in approximately 30% of patients

usually present with symmetrical, proximal muscle weakness in the upper and lower extremities.

Patients with polymyositis may report muscle pain and tenderness, which may be confused with symptoms of polymyalgia rheumatica.

all of the muscles usually involved Muscle weakness may fluctuate from week

to week or from month to month.

Dysphagia secondary to oropharyngeal and esophageal involvement occurs in about one third of patients with polymyositis and is a poor prognostic sign.

Facial and bulbar muscle weakness is extremely rare in individuals with polymyositis.

Etiology :• Polymyositis is an immune-mediated

syndrome .• secondary to defective cellular immunity • commonly associated with other systemic

autoimmune diseases

General◦ criteria

proximal muscle weakness elevated serum CPK myopathic changes on EMG muscle biopsy inflammation definitive with four, probable with three, possible

with two dermatomyositis skin rash with above

General◦ labs

anti-tRNA synthetases◦ up to 20% associated with malignancy

lung, ovary, breast, stomach parotid, tonsil reported dermatomyositis with nasopharyngeal carcinoma,

endemic areas

Head and Neck Manifestations◦ weakness neck muscles◦ difficulty phonation, deglutition, nasal

regurgitation◦ dysphagia from upper esophagus◦ may result in aspiration pneumonia

Enzyme levelsSerum creatine kinase (CK) levels are usually

elevated in persons with polymyositis, ranging from 5-50 times the reference range. A level greater than 100 times the reference level is rare and is a signal of other diagnoses.

Other muscle enzymes that may be elevated include the following:

Lactic dehydrogenase Aspartate aminotransferase Alanine aminotransferase Aldolase - In practice, usually only the CK

and aldolase levels are determined

ElectromyographyElectromyographic findings are abnormal in

almost all patients (90%) with polymyositis. Various abnormalities consistent with polymyositis may be found, depending on the stage of disease

Biopsy Muscle biopsy is crucial in helping to

diagnose polymyositis and in excluding other rare muscle diseases

Inflammatory changes are seen at muscle biopsy (eg, deltoid or quadriceps femoris).

Treatment◦ steroids if symptomatic◦ methotrexate, immunosuppresives nonresponders◦ H2 blockers◦ metoclopromide

Corticosteroids Prednisone is the first-line treatment of

choice for polymyositis. Typically, the dose is 1 mg/kg/day, either as a single or divided dose. This high dose is usually continued for 4-8 weeks, until the CK level returns to reference ranges. Taper prednisone by 5-10 mg on a monthly basis until the lowest dose that controls the disease is reached.

Monitor response to therapy based on improvement in muscle strength and muscle endurance and decrease in CK levels.

Immunosuppressants Immunosuppressive agents are indicated in

patients who do not improve with steroids within a reasonable period (ie, 4 wk) or in whom adverse effects from corticosteroids develop

Patients with poor prognostic indicators, such as dysphagia or dysphonia, are likely to require immunosuppressive agents.

Other agents Intravenous immunoglobulin (IVIG) has

been used for the short-term treatment of steroid-resistant cases of polymyositis.

Diet Patients with polymyositis may benefit from

a high-protein diet. Monitor patients to avoid excessive weight gain due to corticosteroid use.

Activity During the acute stage of polymyositis,

patients may benefit from heat therapy, passive range-of-motion exercises, and splints to avoid contractures.

Etiologi : Pemakaian kortiko steroid Gangguan metabolik (hipoglikemi kronik,

myiglobinuria miopatik, penyakit penimbunan glikogen)

Gangguan endokrin (tirotoksikosis, sindroma cushing, penyakit addison)