Abstract
Idiopathic inflammatory myopathies are an unusual group of myopathies with annual incidence of 1 in 100 000 people in the United States. Necrotizing autoimmune myopathy comprises only 16% of this group. It usually presents with severe proximal weakness, lower extremity weakness, and severe fatigue while very rarely does it present with dysphagia and respiratory muscle weakness. Statin use, cancer, and connective tissue disorder are the usual associated risk factors. Anti-signal recognition particle and 3-hydroxy-3-methylglutaryl-coenzyme A reductase are the 2 most common autoantibodies associated with necrotizing autoimmune myopathy. In this article, we present a very rare case of a 66-year-old male who presented with shortness of breath and dysphagia requiring intubation and ventilator support. Creatine kinase was 23 000, myoglobin was 7000, and ANA was positive. All other autoimmune and infectious workup including Lyme disease was unremarkable. Muscle biopsy turned out remarkable for necrotizing myopathy. No evidence of statin use, active malignancy, or connective tissue disease was found. He was treated with high-dose corticosteroids and a short course of intravenous immunoglobulin with very mild improvement in symptoms. Anti-signal recognition particle and 3-hydroxy-3-methylglutaryl-coenzyme A reductase could not be performed as the patient refused to pursue further medical testing. This is a very rare case of idiopathic inflammatory myopathy presenting with bulbar and respiratory muscle weakness requiring ventilator support.
Highlights
Necrotizing autoimmune myopathy (NAM) is an unusual and rare subgroup of inflammatory myopathies
Several risk factors including statin use (34%), malignancy (9.5%), and connective tissue diseases (4.2%) have been identified, whereas more than 50% were idiopathic in nature
Magnetic resonance imaging of cervical, thoracic, and lumbosacral spine did not show any evidence of cord compression or radiculopathy, but diffuse myositis was noticed in all paraspinal muscles
Summary
Necrotizing autoimmune myopathy (NAM) is an unusual and rare subgroup of inflammatory myopathies. A 66-year-old Caucasian male with no known past medical history presented with bilateral lower extremity weakness for 4 weeks He initially went to a chiropractor and on no improvement sought medical attention. Diarrhea, rash, statin use, and tick bites. He denied any vision loss, diplopia, active malignancy, or family history of any neurological disorder. The patient showed some improvement in muscle strength with corticosteroid therapy, refused muscle biopsy, and was discharged home on tapering dose of steroids. One week later he again presented to the hospital with dysphagia and shortness of breath. Anti-scleroderma Anti-centromere Cryoglobulin ANA Anti-Hu SSB (LA) and SSB (RO) Anti-Jo 1 Aldolase MuSK Ab
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