Abstract:

Objective To investigate the clinical manifestations and auxiliary examination features of necrotizing autoimmune myopathy (NAM). Methods According to the inclusion criteria from European Neuromuscular Center (ENMC) International Workshop on idiopathic inflammatory myopathies published in 2004, 57 patients were diagnosed as NAM from 107 patients with necrotizing myopathy (NM). The risk factors, clinical symptoms, laboratory tests, electrocardiography (ECG), electromyography (EMG), skeletal muscle MRI and muscle pathology were retrospectively analyzed. Results There were more female patients than male patients (male∶female = 1.00∶1.59), with the peak onset age during 40 to 59 years old (43.86% , 25/57) in this study. Clinical types included idiopathic NAM, NAM with connective tissue disease, statin-associated NAM and NAM with cancer. Muscle weakness mainly affected proximal muscle, while it may simultaneously affect distal muscle (28.07% , 16/57). Serum creatine kinase (CK) elevated apparently (420-15 320 U/L). Serum anti-signal recognition particle (SRP) antibodies were detected in 24 out of 44 patients (54.55%). A total of 41 in 45 patients (91.11%) were detected myogenic damage on EMG, and 15 patients (33.33%, 15/45) also had spontaneous potentials. Thigh muscle MRI showed edema in 25 out of 27 patients (92.59% ) and fatty infiltration in 16 out of 27 patients (59.26% ). Other than necrotic fibers, major histocompatibility complex-1 (MHC-1) on sarcolemma were positive in 98.25% (56/57) cases, and membrane attack complex (MAC) deposition on capillary walls was detected in 92.98% (53/57) cases. Conclusions NAM can happen in all ages, mainly during 40 to 59 years old. Idiopathic NAM is the main type. Its main manifestation involves weakness of proximal muscle, sometimes with distal muscle. Extra-muscle symptoms are rare. Serum anti-SRP antibodies are common in NAM and edema is prominent change in thigh MRI.

Key words: Myositis, Autoimmune diseases, Signal recognition particle, Electromyography, Magnetic resonance imaging

摘要：

目的 探讨免疫性坏死性肌病的临床表现和辅助检查特点。方法 共107 例坏死性肌病患者，采用2004 年欧洲神经肌肉病中心公布的特发性炎性肌病分类标准中免疫性坏死性肌病诊断标准，57 例明确诊断为免疫性坏死性肌病，回顾分析其危险因素、临床表现、实验室检查、心电图、肌电图、骨骼肌MRI 和肌肉病理学特点。结果 57 例患者中女性患者比例略高于男性（男女比例1.00∶1.59），高峰发病年龄40 ~ 59 岁（43.86%，25/57）；临床分型包括特发性免疫性坏死性肌病、结缔组织病相关性免疫性坏死性肌病、他汀相关性免疫性坏死性肌病、肿瘤相关性免疫性坏死性肌病；临床症状均以近端肌无力为主，可同时出现远端肌无力（28.07%，16/57）；血清肌酸激酶水平升高（420 ~ 15 320 U/L）；血清抗信号识别颗粒抗体阳性率较高（54.55%，24/44）；肌电图呈现肌源性损害（91.11%，41/45）和自发性电位（33.33%，15/45）；大腿肌肉MRI 可见肌肉水肿（92.59%，25/27）和脂肪浸润（59.26%，16/27）；肌肉病理学除坏死肌纤维外，亦可见肌纤维膜主要组织相容性复合物-1 阳性（98.25%，56/57）和毛细血管壁膜攻击复合物沉积（92.98%，53/57）。结论 免疫性坏死性肌病各年龄阶段均可发病，高峰发病年龄为40 ~ 59 岁，特发性免疫性坏死性肌病为最常见的临床亚型，临床主要表现为近端或远近端肌无力，骨骼肌以外系统受累少见，血清抗SRP 抗体阳性率较高，大腿肌肉MRI以肌肉水肿改变为主。

关键词: 肌炎, 自身免疫疾病, 信号识别颗粒, 肌电描记术, 磁共振成像