RESUMEN
INTRODUCTION: Anti-3-hydroxy-3-méthylglutaryl-coenzyme A reductase antibody-associated necrotizing autoimmune myopathy has been recently described (2011). This myopathy is distinct from statin toxic myopathy. Our objective is to report on the clinical and para-clinical characteristics of this myopathy and to show the difficulties of therapeutic care. CASE REPORTS: We describe 4 cases of patients followed-up in Brittany, France. All data have been analyzed retrospectively. The mean age of our patients was 59.5 years, with a sex ratio of 1. The clinical presentation was homogeneous, with a subacute painful proximal and symmetrical weakness, without extra-muscular involvement. Other presentations have been described (including pseudo-dystrophic presentation). All patients had a previous statin medication (mean duration of 3.75 years) although this criteria is not a requisite. All patients had high levels of creatine kinase and abnormal electromyographic examination. The pathological pattern on muscular biopsy was a necrotizing myopathy without significant inflammatory cells infiltration. Cardio-respiratory function was normal and no associated neoplasia was found. Over the follow-up, we observed a marked corticosteroid-dependence, not improved by immunosuppressive drugs (azathioprine and methotrexate). The benefit of intravenous immunoglobulin was clear with, sometimes, prolonged responses. CONCLUSION: An early diagnosis of this myopathy is necessary in order to introduce an immunotherapy associated with a close monitoring. The therapeutic strategy (within which the stead of intravenous immunoglobulin seems increased) remains to be defined and long-term prospective studies are thus needed.
Asunto(s)
Autoanticuerpos/efectos adversos , Enfermedades Autoinmunes/diagnóstico , Hidroximetilglutaril-CoA Reductasas/inmunología , Músculo Esquelético/patología , Enfermedades Musculares/diagnóstico , Anciano , Autoanticuerpos/sangre , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/complicaciones , Enfermedades Autoinmunes/inmunología , Femenino , Francia , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Musculares/complicaciones , Enfermedades Musculares/inmunología , Enfermedades Musculares/patología , Necrosis/complicaciones , Estudios RetrospectivosRESUMEN
Monoclonal IgM anti-MAG associated peripheral neuropathies are part of demyelinating dysimmune peripheral neuropathies. The hematological disease probably does not influence the outcome of the neuropathy. Neuropathies associated with IgM anti-MAG antibodies are predominantly sensory and distal polyneuropathies associated with ataxia, unsteadiness and tremor. The neurophysiological features include a symmetric sensorimotor demyelinating neuropathy with more slowing of conduction in the distal than in the proximal nerve segments, a length-dependence, and a variable degree of denervation. High titers of IgM anti-MAG antibodies confirm the diagnosis. The natural history is mostly slow with mild to moderate functional impairment. However, some patients have a faster evolution associated with a more severe handicap. Immunotherapies studies have failed to demonstrate significant efficacy of these treatments. Furthermore, severe adverse effects are not uncommon with any of these therapies. Thus, the risk of possible severe adverse effects must be balanced against any possible benefits. More research is needed to improve the management of anti-MAG neuropathies: research on treatment, on prognostic factors, and development of specific assessment scales adapted to the particularities of anti-MAG neuropathies.