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Título

NECROTIZING MYOPATHY RELATED TO ARBOVIROSIS – CASE REPORT

RESUMO

Case presentation: A 35-year-old man, 3 weeks after a febrile condition with polyarthralgia, evolved with proximal lower limb weakness and subsequent progression to upper limbs. He denied myalgia, cramps, myoglobinuria, falls, respiratory complaints, dysphagia or dysphonia. Neurological examination revealed scapular and pelvic muscle wasting, proximal weakness, hypoactive deep tendon reflexes and waddling gait. Laboratory investigation revealed high levels of creatine phosphokinase (CPK: 11,591 UI/L), lactate dehydrogenase (DHL: 1420 U/L) and positive IgG serology for chikungunya (Elisa). Electroneuromyography showed a myopathic pattern. Muscle biopsy, performed at right biceps brachialis, revealed several necrotic and regenerating myofibers, with scarce perivascular inflammatory infiltrate, several CD68+ cells, rares CD8+ cells and no CD4+ cells, consistent with necrotizing myopathy. The patient was then treated with prednisone 1mg/kg/day. However, due to increasing CPK levels and persistence of weakness, human intravenous immunoglobulin (2g/kg in 5 days) was added to treatment. The patient was discharged with prednisone 1mg/kg/day and methotrexate 10mg per week. After 45 days, in follow up visit, patient showed significant improvement in muscle strength, normal gait and normalization of CPK and DHL levels. Prednisone was tapered and methotrexate was maintained. Discussion: Immunemediated necrotizing myopathy is a inflammatory myopathy, characterized by proximal muscle weakness, high CPK levels, necrotic and regenerating fibers and macrophagy in muscle biopsy, as well as good response to immune therapy. Necrotizing myopathy is related to various etiologies, such as use of statins, neoplasms and viral infections. One of the viral causes, the chikungunya virus, an alphavirus present throughout the Brazilian territory, presents with a febrile disease with intense arthralgia. Neurological complications include encephalitis and myelitis; there are reports of cases with peripheral nervous system involvement, including skeletal muscle. Final considerations: Arbovirosis-related necrotizing myopathy is a rarely reported entity, and there is still discussion about the best therapeutic approach. We reinforce the clinical response with the use of intravenous intravenous immunoglobulin; however, long-term immunosuppressive therapy remains a recommendation in the follow-up of these patients.

Palavras Chave

Arbovirus Infections ; Muscle weakness ; Myositis ; Immunoglobulins, Intravenous