Myopathic changes detected by quantitative electromyography in patients with MuSK and AChR positive myasthenia gravis

Myopathic changes are frequent a electrophysiological finding in patients with muscle specific tyrosine kinase (MuSK) positive myasthenia gravis (MG). The aim of this study was to explore the importance of quantitative electromyography (EMG) in the detection of myopathic changes in MuSK MG patients. Classical and quantitative EMG were performed in 31 MuSK and 28 acetylcholine receptor (AChR) positive MG patients, matched by sex, age, disease duration and severity. Classical EMG revealed the presence of myopathic changes more frequently in MuSK MG compared to AChR MG patients, especially in the facial muscles. Quantitative EMG registered myopathic lesions more frequently than classical EMG, but the frequency was similar between MuSK and AChR MG patients. Quantitative EMG revealed myopathic changes in the majority of both MuSK and AChR positive MG patients. This examination is sensitive, but it cannot be used to differentiate between MG patients belonging to the different disease groups. It should not be used in isolation. Rather, it should complement classical EMG in the detection of myopathic changes.     

Prepubertal anti-Musk positive myasthenia gravis with long remission

Anti-MuSK positive myasthenia gravis (MuSK-MG) is rare prepuberty. We report a female patient with MuSK-MG starting at 3.5 years with ptosis as the sole symptom for 2 years. A brief period of generalization was followed by complete stable remission for 6 years. Prolonged ocular symptoms and long remissions are not features of MuSK-MG, but are often seen in prepubertal onset MG. The patient then presented at age 12 with moderately severe symptoms which were almost confined to oculobulbar muscles and were unresponsive to pyridostigmine. She was dependent on corticosteroids and thymectomy did not seem to be effective. She was later noted to have tongue atrophy after a period without treatment. Our patient thus presented with features seen in many prepubertal patients, but the later course was quite typical of MuSK-MG.     

Cholinergic neuromuscular hyperactivity in patients with myasthenia gravis seropositive for MuSK antibody

A 75-year-old man with severe oculobulbar myasthenia gravis (MG) treated with acetylcholine esterase inhibitors (AChEIs) was found to have muscle-specific tyrosine kinase (MuSK) antibodies. Neurophysiological examination displayed extra repetitive discharges after the compound motor action potential (CMAP) at low-frequency stimulation, possibly triggered by AChEI. This indicates an abnormal sensitivity to acetylcholine in patients with MuSK antibodies and may be a useful indicator of the adverse effect of AChEI treatment in these patients.     

Successful treatment of MuSK antibody-positive myasthenia gravis with rituximab

We report on a 56-year-old woman with muscle-specific receptor tyrosine kinase (MuSK) antibody-positive myasthenia with predominant bulbar symptoms and respiratory insufficiency. Conventional immunosuppression (prednisolone, azathioprine, mycophenolate mofetil) could not maintain the clinical improvement initially achieved by repeated plasma exchanges. Therefore, treatment with rituximab was initiated. After 2 months of rituximab treatment, remarkable clinical improvement correlating with a reduction of MuSK serum antibodies was seen. The patient continued to remain stable 12 months after initiation of therapy. This case report demonstrates that rituximab may be an effective and tolerable treatment in MuSK antibody-positive myasthenia gravis.     

重症肌无力的电生理研究

目的探讨重症肌无力（ＭＧ）患者的电生理特征及其诊断价值。方法应用针极肌电图（ＥＭＧ），重复神经电刺激（ＲＮＳ）和激发重复神经电刺激（ＡＲＮＳ）方法，对４７例ＭＧ患者的肌肉和神经肌肉传递功能进行研究。结果部分患者的肌肉见到病理自发电位及短小动作电位，具近端肌分布特征。ＡＲＮＳ阳性率（９０．６％）较ＲＮＳ阳性率（８３．０％）高。Ⅰ型患者肢体肌群存在多项电生理异常。结论适当、综合应用电生理检测技术有助于ＭＧ的早期诊断     

Clinical fluctuations in MuSK myasthenia gravis are related to antigen-specific IgG4 instead of IgG1

We studied the longitudinal relation between disease severity and titers of antigen-specific IgG subclasses in sera of patients with myasthenia gravis and antibodies to Muscle Specific Kinase (MuSK MG). Six patients were included of whom 55 samples had been collected during 2.5–13.4 years. Anti-MuSK antibodies were determined by ELISA and with a cell-based immunofluorescence assay. Disease severity was scored on a semi continuous scale. Only antigen-specific IgG4, and not IgG1, titers were significantly associated with disease severity in a linear mixed effect model (p = 0.036). Levels of IgG4 antibodies were above IgG1 in all samples except in one patient who went into clinical remission while switching from IgG4 to IgG1. The results support an important role for IgG4 in the pathogenesis of MuSK MG, in contrast to MG with anti-acetylcholine receptor antibodies.     

AChR抗体阳性重症肌无力合并舌肌萎缩2例报道并文献分析

目的 探讨重症肌无力(MG)患者合并舌肌萎缩的发病特点及机制。方法 分析武汉同济医院神经内科住院部2例乙酰胆碱受体(AChR)抗体阳性MG患者合并舌肌萎缩的临床资料,检索MG合并舌肌萎缩的文献报道,总结此类疾病的特点、萎缩机制、治疗方法及预后。结果 在临床上MG合并舌肌萎缩并不多见,大多数患者伴有血清肌肉特异性酪氨酸肌酶(MuSK)抗体阳性,伴AChR抗体阳性者较为罕见,肌肉萎缩的发病机制具体不详; 该类患者除发病时间较长外,通常提示更严重的病情、更差的治疗反应、更不良的预后。结论 MG舌肌萎缩临床少见,严重影响着患者的言语、咀嚼和吞咽等功能,除病程较长外,其肌肉萎缩机制暂不清楚,有待临床进一步探索,以改善此类患者预后和生活质量。     

High-dose intravenous immunoglobulin for the treatment of MuSK antibody-positive seronegative myasthenia gravis

We treated two patients with anti-muscle specific tyrosine kinase (MuSK)-antibody positive seronegative myasthenia gravis (MG) with high-dose intravenous gammaglobulin (IVIg) and evaluated their clinical courses. Both patients were Japanese women, MuSK-positive seronegative MG, and were unresponsive to conventional treatments, including thymectomy, steroids, and tacrolimus. The patients required frequent hospitalization for plasmapheresis. In case 1, a 45-year-old woman, it was difficult to obtain blood access for plasmapheresis. High-dose IVIg, 400 mg/kg per day for 5 days, was administered in cases 1 and 2. In both cases, clinical improvement was observed 3 days after the start of IVIg therapy and lasted for 2 to 3 months. We propose that IVIg therapy is an effective treatment for MuSK-positive seronegative MG, when conventional treatments have failed.     

High-dose cyclophosphamide in refractory myasthenia gravis with MuSK antibodies

We describe a 48-year-old woman with seronegative myasthenia gravis (MG) and high-titer of anti-MuSK antibody. She had severe bulbar and respiratory weakness with minimal limb weakness for 2 years. Her disease responded poorly to all the conventional immunosuppressive regimens. Treatment with immunoablative dose of cyclophosphamide led to dramatic and sustained remission of her symptoms. High-dose cyclophosphamide is an effective alternative in patients with unusually refractory disease.     

Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis

Introduction: A randomized trial demonstrated benefit from thymectomy in nonthymomatous acetylcholine receptor (AChR)-antibody positive myasthenia gravis (MG). Uncontrolled observational and histologic studies suggest thymectomy may not be efficacious in anti–muscle-specific kinase (MuSK)-MG. Methods: The therapeutic impact of thymectomy was evaluated from data collected for a multicenter, retrospective blinded review of rituximab in MuSK-MG. Results: Baseline characteristics were similar between thymectomy (n = 26) and nonthymectomy (n = 29) groups, including treatment with rituximab (42% vs. 45%). At last visit, 35% of thymectomy subjects reached the primary endpoint, a Myasthenia Gravis Foundation of America (MGFA) post-intervention status (PIS) score of minimal manifestations (MM) or better, compared with 55% of controls (P = 0.17). After controlling for age at onset of MG, rituximab, prednisone, and intravenous immunoglobulin/plasma exchange treatment, thymectomy was not associated with greater likelihood of favorable clinical outcome (odds ratio = 0.43, 95% confidence interval 0.12–1.53, P = 0.19). Discussion: Thymectomy was not associated with additional clinical improvement in this multicenter cohort of MuSK-MG patients. Muscle Nerve 59:404–410, 2019     

伴胸腺瘤重症肌无力的临床特点(附96例分析)

目的　研究伴胸腺瘤重症肌无力的临床特点。方法　对经手术病检证实的 96例MG伴胸腺瘤患者的临床资料进行回顾性分析 ,并采用 χ2 检验及t检验与 114 9例经影像学检查无胸腺瘤表现的MG患者进行比较。结果　胸腺瘤组男性发病者多 (男∶女 =1 82∶1) ,且多于 30岁后发病 (71 9% ) ,以肢体无力和延髓症状首发者多见 (4 3 8% ) ,按改良Os serman分型 ,以Ⅲ型和Ⅳ型为主 (4 5 8% ) ,危象发生率高 (38 5 % ) ,病死率高 (8 3 % )。结论　伴胸腺瘤的重症肌无力有其独特临床特点 ,充分认识这些特点将有利于指导对这类患者的临床诊断和治疗     

Muscle atrophy in muscle-specific tyrosine kinase (MuSK)-related myasthenia gravis

Myasthenia gravis (MG) with muscle-specific tyrosine kinase (MuSK) antibody (MuSK-MG) is often associated with prominent facial and bulbar muscle atrophy. It remains unclear whether the muscle atrophy is a consequence of long-term corticosteroid treatment, or of the disease process per se. Herein, we report a steroid-naive patient with MuSK-MG who presented with severe weakness and marked atrophy of the facial and tongue muscles.     

218例重症肌无力危象的临床分析

目的总结重症肌无力危象的临床特点及急救和预防经验.方法回顾性分析1956～2004年诊治的218例患者369例次重症肌无力危象的病例资料.结果死亡51例,病死率23.39%;近十年(1994～2004年)死亡4人,病死率4.2%.结论综合利用气管切开正压辅助呼吸、激素冲击治疗、丙种球蛋白静滴及血浆交换可改善重症肌无力危象的预后,且明显降低病死率.     

Epidemiological and immunological profile of muscle-specific kinase myasthenia gravis in Greece

Objectives:  The purposes of this study were to determine the epidemiological characteristics of muscle-specific kinase-myasthenia gravis (MuSK-MG) in Greece and the IgG subclass of the anti-MuSK antibodies.
Methods:  This population-based study was performed on MuSK-MG patients in Greece between 1 January 1986 and 30 June 2006. Epidemiological and clinical data for 33 patients were collected. In addition, the distribution of anti-MuSK IgG autoantibody subclasses in the sera of 14 patients was determined by immunoprecipitation.
Results:  The average annual incidence was 0.32 patients/million population/year. On 1st July 2006, there were 33 prevalent cases, giving a point prevalence rate of 2.92/million (women 4.56 and men 1.25). In females, onset of MuSK-MG occurred after the age of 30, whilst, in males, the disease appears in any decade. The female:male incidence ratio was 3.33:1, whilst the prevalence ratio was 3.65:1. Most patients presented with involvement of the facial and bulbar muscles. Amongst about 800 MG patients seropositive for antibodies against either the AChR or MuSK, one patient was found to be seropositive for anti-MuSK antibodies and ambiguous for anti-acetylcholine receptor (anti-AChR) antibodies. The vast majority of anti-MuSK antibodies were IgG4, whilst total IgG4 levels in these patients were similar to those in two healthy controls.
Conclusions:  The incidence and prevalence of MuSK-MG in Greece are amongst the highest reported previously for other countries. MuSK-MG in Greece affects both sexes, but mainly females. The main epidemiological indices were calculated. The vast majority of anti-MuSK antibodies were IgG4.     

伴其他自身免疫性疾病的重症肌无力临床特点分析

目的分析伴其他自身免疫性疾病的重症肌无力患者之临床特点、药物疗效、预后和转归。方法共83例重症肌无力患者,分为伴其他自身免疫性疾病重症肌无力(AIDMG)组(24例)和不伴其他自身免疫性疾病重症肌无力(NAIDMG)组(59例),比较两组患者性别、发病年龄、首发症状、胸腺异常等临床特点、不同治疗措施之疗效和预后。结果两组患者性别(χ2=8.467,P=0.004)、眼睑下垂侧别(χ2=9.830,P=0.007)、发病2年内病程情况(χ2=15.255,P=0.001)差异具有统计学意义,而发病年龄(χ2=1.728,P=0.228)、首发症状(χ2=0.252,P=0.791)、胸腺异常(χ2=3.200,P=0.202)组间差异无统计学意义。两组患者溴吡斯的明(χ2=0.411,P=0.395)、糖皮质激素(χ2=0.156,P=0.513)、静脉注射免疫球蛋白(χ2=0.359,P=0.462)、免疫抑制剂(χ2=0.081,P=0.526)、胸腺切除术(χ2=0.337,P=0.391)等治疗措施之疗效,以及眼肌型重症肌无力进展为全身型重症肌无力比例(χ2=1.826,P=0.148)、进展时间(Fisher确切概率法:P=0.639)、首发症状(Fisher确切概率法:P=0.196)和复发时间(Fisher确切概率法:P=1.000)差异均无统计学意义。结论 AIDMG患者多见于女性,首发症状为眼睑下垂,以双侧同时受累为主;发病2年内较NAIDMG患者更易复发。     

Immunosuppressive treatment of rippling muscles in patients with myasthenia gravis

Rippling muscle disease is a rare autosomal dominant disorder that may occur sporadically. In this report two patients presenting with rippling muscles followed by myasthenia gravis are described. Our first patient developed rippling muscles about 1 month after infection with Yersinia enterocolitica. Two years later myasthenia gravis appeared. Our second patient had a 2-year history of asthma prior to the onset of rippling muscles which preceded the myasthenic symptoms by 4–8 weeks. Acetylcholine receptor and anti-skeletal muscle antibody titers were positive in both patients. In both patients the rippling phenomena worsened with pyridostigmine treatment but markedly improved after immunosuppression with azathioprine.     

儿童重症肌无力伴甲状腺功能亢进88例临床分析

目的研究儿童重症肌无力(MG)伴甲状腺功能亢进症(甲亢)的临床特点及治疗.方法对88例儿童MG伴甲亢患者的临床资料和治疗方法进行回顾性研究,并与同时期成人MG伴甲亢患者进行比较.结果男性35例,女性53例;就诊时MG患者Ⅰ型72例,ⅡA型8例,ⅡB型6例,Ⅳ型2例;先有甲亢后有MG18例,先有MG后有甲亢34例,MG和甲亢同时发生36例;合并癫痫6例,伴胸腺增生16例;经过治疗60.23%的患者痊愈,7.95%的患者无效.结论儿童与成年人MG合并甲亢患者在性别上发病无统计学差异,而临床类型分布不同,儿童组以Ⅰ型多见;两种疾病的发生顺序不同,儿童先发生甲亢者较少,成人组先发生甲亢者多见.儿童MG伴甲亢患者的临床表现复杂,诊断较难,容易误诊和漏诊,提高对本病的认识是改善预后的关键.     

眼肌型重症肌无力进展为全身型重症肌无力的临床相关因素分析

目的 :探讨眼肌型重症肌无力进展为全身型重症肌无力的临床相关预测因素。方法 :33例初诊为眼肌型重症肌无力的患者经过3年随访,根据疾病进展结局分为眼肌型重症肌无力组(13例)和进展为全身型重症肌无力组(20例)。对与疾病进展可能相关的临床因素进行分析。结果 :进展为全身型重症肌无力组患者初诊时的定量重症肌无力评分、乙酰胆碱受体抗体阳性率、抗核抗体阳性率、合并胸腺瘤的比例以及合并糖尿病的比例均高于眼肌型重症肌无力组(P值均0.05)。结论 :定量重症肌无力评分高、乙酰胆碱受体抗体阳性、抗核抗体阳性以及合并胸腺瘤和糖尿病可能是眼肌型重症肌无力进展为全身型重症肌无力的预测指标。     

重症肌无力患者神经肌肉接头处的超微结构研究

目的探讨重症肌无力（ＭＧ）时神经肌肉接头（ＮＭＪ）突触后、前膜的变化及其意义。方法肋间内肌在辣根过氧化酶标记的α银环蛇毒素（ＨＲＰαＢｕＴｘ）标记后，用图形扫描及医学图像分析软件测量电镜照片中ＮＭＪ的各项指标，并与对照组比较分析。结果ＭＧ时突触后膜长度缩短，后、前膜长度比值变小，神经末端面积及其与突触后膜面积之比变小，突触后膜上的乙酰胆碱受体（ＡＣｈＲ）减少了３５．９％。结论ＭＧ时ＮＭＪ的变化主要存在于突触后膜。突触后、前膜长度之比对本病的诊断更有临床意义。