Amato A A, Barohn R J
Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115, USA.
J Neurol Neurosurg Psychiatry. 2009 Nov;80(11):1186-93. doi: 10.1136/jnnp.2009.173823.
Inclusion body myositis (IBM) is the most common idiopathic inflammatory myopathy occurring in patients over the age of 50 years and probably accounts for about 30% of all inflammatory myopathies. Muscle biopsy characteristically reveals endomysial inflammation, small groups of atrophic fibres, eosinophilic cytoplasmic inclusions and muscle fibres with one or more rimmed vacuoles. However, any given biopsy may lack these histopathological abnormalities; the clinical examination is often the key to diagnosis. Early and often asymmetrical weakness and atrophy of the quadriceps and flexor forearm muscles (ie, wrist and finger flexors) are the clinical hallmarks of IBM. The pathogenesis of IBM is unknown. It may be autoimmune inflammatory myopathy or a primary degenerative myopathy with a secondary inflammatory. A prevailing theory is that there is an overproduction of beta-amyloid precursor protein in muscle fibres that is somehow cleaved into abnormal beta-amyloid, and the accumulation of the latter is somehow toxic to muscle fibres. However, there are many problems with this theory and more work needs to be done. Unfortunately, IBM is generally refractory to therapy. Further research into the pathogenesis, along with both preliminary small pilot trials and larger double blind, placebo controlled efficacy trials, are needed to make progress in our understanding and therapeutic approach for this disorder.
包涵体肌炎（IBM）是最常见的特发性炎性肌病，发生于50岁以上的患者，约占所有炎性肌病的30%。肌肉活检的特征性表现为肌内膜炎症、小群萎缩纤维、嗜酸性胞质包涵体以及有一个或多个镶边空泡的肌纤维。然而，任何一次活检都可能缺乏这些组织病理学异常；临床检查往往是诊断的关键。股四头肌和前臂屈肌（即腕部和手指屈肌）早期且常为不对称性无力和萎缩是IBM的临床特征。IBM的发病机制尚不清楚。它可能是自身免疫性炎性肌病，也可能是继发炎症的原发性变性性肌病。一种流行的理论认为，肌纤维中β-淀粉样前体蛋白过度产生，以某种方式裂解为异常的β-淀粉样蛋白，后者的积累对肌纤维有某种毒性。然而，该理论存在许多问题，还需要做更多的工作。不幸的是，IBM通常对治疗无效。需要对发病机制进行进一步研究，并开展初步的小型试验以及更大规模的双盲、安慰剂对照疗效试验，以便在我们对这种疾病的认识和治疗方法上取得进展。
