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Inflammatory myopathy with cytochrome oxidase negative muscle fibers: Methotrexate treatment
Author(s) -
Levine Todd D.,
Pestronk Alan
Publication year - 1998
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199812)21:12<1724::aid-mus15>3.0.co;2-2
Subject(s) - muscle biopsy , inclusion body myositis , myositis , myopathy , methotrexate , medicine , inflammatory myopathy , muscle weakness , cytochrome c oxidase , mitochondrial myopathy , gastroenterology , biopsy , endocrinology , pathology , biology , mitochondrion , biochemistry , mitochondrial dna , gene
Inflammatory myopathy with cytochrome oxidase negative muscle fibers (IM/COX−) is characterized by slowly progressive weakness, most prominent in the quadriceps, muscle fibers with reduced COX staining and mitochondrial DNA mutations, and a poor response to corticosteroid treatment. We reviewed records of quantitative measurements of muscle strength in 7 IM/COX− patients to evaluate the outcomes after treatment with oral, once weekly, methotrexate for an average of 15 months. We compared the results to 6 patients with IM/COX− who received no long‐term immunosuppression, and to 4 with inclusion body myositis (IBM) who received methotrexate during the same period. Methotrexate treatment of IM/COX− was followed by improved muscle strength in 5 of 7 patients, averaging 17 ± 5%. In contrast, there was no improvement in the strength of 6 untreated IM/COX− patients (−6 ± 4%; P = 0.003), or 4 methotrexate‐treated IBM patients (1 ± 2%; P = 0.03). We conclude that, despite clinical similarities to inclusion body myositis, which is usually refractory to immunosuppressive therapy, strength in IM/COX− appears to improve with methotrexate treatment. Biopsy studies of inflammatory myopathies with evaluation of muscle for mitochondrial changes and vacuoles can help to direct the choice of appropriate immunomodulating treatments. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1724–1728, 1998