Paraneoplastic myasthenia gravis: immunological and clinical aspects

Paraneoplastic myasthenia gravis (MG) is accompanied by a neoplasm, usually thymoma. In patients with thymoma and a specific genetic make‐up, the paraneoplastic immune response develops further in thymic remnant or peripheral lymphatic tissue. Paraneoplastic MG and late‐onset MG (age ≥ 50 years) share a similar immunological profile with high titin and ryanodine receptor (RyR) antibody prevalence. This profile is the most important predictor of clinical outcome in paraneoplastic MG. The presence of a thymoma per se does not cause more severe MG. MG severity is linked to the patient’s immunological profile. Paraneoplastic MG causes a distinctive non‐limb symptom profile at MG onset, characterized by bulbar, ocular, neck, and respiratory symptoms. When the diagnosis of paraneoplastic MG is established, the neoplasm should be removed surgically. Pre‐thymectomy plasmapheresis or iv‐IgG should be considered in these patients to minimize post‐thymectomy MG exacerbation risk. Paraneoplastic MG usually continues after thymectomy. The pharmacological treatment of paraneoplastic MG does not differ from non‐paraneoplastic MG, except for tacrolimus that should be considered in difficult cases. Tacrolimus is an immunosuppressant acting specifically in RyR antibody positive patients through enhancing RyR‐related sarcoplasmic calcium release that in theory might be blocked by RyR antibodies, causing symptomatic relief in paraneoplastic MG.     

老年重症肌无力住院患者48例临床特点分析

目的分析老年重症肌无力(MG)住院患者的有关临床特点。方法回顾性分析近年来在我院住院诊治的48例老年MG患者的临床资料。结果老年MG患者占总住院MG病例数(175例)的比例为27.4%。男性多于女性,男∶女=2.7∶1。老年MG多在60~69岁之间发病,在其常见首发症状中,眼部症状最多,为34例(70.8%)、球麻痹其次,为8例(16.7%)、肢体肌无力5例(10.4%)、肌萎缩1例(2.1%)。老年MG患者中,全身型比例(70.8%)显著高于眼肌型(29.2%),较少合并自身免疫性疾病和发生危象,常合并胸腺病变(17例)及其他内外科疾病(36例),其中15例为胸腺瘤。伴胸腺病变的老年MG患者出现首发症状的年龄与无胸腺病变的老年MG患者比较差异无统计学意义;而伴胸腺病变的老年MG患者需住院治疗时的年龄显著小于无胸腺病变的老年MG患者,差异有统计学意义(P0.05)。结论老年MG具有其自身特点,男性多见,早期表现多为眼肌无力,全身型比例高于眼肌型,胸腺病变主要为胸腺瘤,危象发生率较低等临床特点。     

重症肌无力患者血清连接素抗体与临床的关系

目的 探讨重症肌无力（MG）患者血清连接素抗体（Titin—Ab）水平与病情及胸腺异常的关系,以及其对诊断和预后判断的价值。方法 应用酶联免疫吸附法（ELISA）检测MG患者（MG组）52例、非MG（其他神经系统疾病）患者（NMG组）18例、健康对照者（NC组）50名血清中Titin—Ab水平,并对其中10例进行胸腺手术的MG患者随访。结果 MG组Titin—Ab阳性率为36．5％,NMG组和NC组均为阴性,MG组显著高于NC组和NMG组（均P〈0．01）;以MG伴胸腺瘤（MGT）组阳性率最高（83．3％）,MG伴胸腺萎缩（MGA）次之（37．5％）,胸腺正常的MG组为23．0％,MG伴胸腺增生组为阴性;Titin．Ab诊断MGT特异性高于胸腺CT（P〈0．05）。Titin—Ab阳性MG患者抗体水平与肌无力程度呈显著正相关（r=0．562,P〈0．01）;对10例不同胸腺病理类型的MG患者手术前后Titin—Ab测定显示差异具有显著性（P〈0．05）。结论 Titin—Ab阳性多见于MGT和MGA者,诊断MGT的特异性高于CT;Titin—Ab对MG的诊断、病情及预后判断均有帮助。     

Heart disease in myasthenia gravis

Patients with myasthenia gravis (MG) may develop heart disease. Our data on 108 MG patients were examined to assess the type and frequency of this. 17 of 108 patients (16%) showed signs of heart disease which could be regarded as MG-related. 11 of these, of whom 5 died suddenly, had clinical symptoms, mainly arrhythmias. Signs of heart disease were most frequent in thymoma patients (5 of 10), and all 3 microscopically examined hearts from these patients showed a focal myocarditis. 44 spinal muscular atrophy patients serving as controls showed a 16% frequency of signs of heart disease of unknown etiology. However, only 1 of 44 spinal muscular atrophy patients (2%) had clinical symptoms as compared to 11 of 108 MG patients (10%). Together with the characteristic focal nature of the myocarditis and the microscopic similarities between lesions of heart and skeletal muscle, this indicates that the heart disease is specifically related to MG.     

不典型眼肌型重症肌无力的临床特点

目的研究不典型眼肌型重症肌无力(OMG)的临床特点。方法回顾性分析29例不典型OMG患者的临床资料。结果本组患者表现为上眼睑下垂3例,单眼1条眼外肌瘫痪15例,双眼3条眼外肌瘫痪1例,单眼全部眼外肌瘫痪1例,辐辏障碍2例,单眼眼轮匝肌瘫痪1例,类似眼病表现6例(复视4例、眼部不适和视物模糊2例,均无眼外肌瘫痪);有晨轻暮重表现12例(41.4%)。新斯的明试验阳性26例(89.7%),低频重复神经电刺激阳性8例(27.6%),单纤维肌电图(SFEMG)异常23例(79.3%)。患者早期均被误诊。经泼尼松和/或胆碱酯酶抑制剂治疗,症状消失26例(89.7%),显著改善3例(10.3%)。结论不典型OMG患者的临床特点为受累眼肌少,症状局限,表现晨轻暮重的比率低。新斯的明试验和SFEMG检查可确诊。     

雷诺丁受体抗体阳性的重症肌无力临床特点

雷诺丁受体（ryanodine receptor, RyR）是存在于内质网/肌质网中的一种重要钙离子通道,在骨骼肌兴奋收缩偶联机制中起重要作用。RyR抗体阳性的重症肌无力（myasthenia gravis, MG）患者常合并胸腺瘤,对常规治疗不敏感,会导致延误临床早期识别及治疗。血清RyR抗体水平与患者临床症状的严重程度显著相关。该文就4例RyR抗体阳性MG患者的临床特点及治疗过程进行讨论并文献复习,旨在提高对RyR抗体阳性MG的认识及诊疗水平。     

HLA class II genotypes in Mexican Mestizo patients with myasthenia gravis.

Myasthenia gravis is an autoimmune, heterogeneous disorder, characterized by the presence of antibodies against acetylcholine receptors at the neuromuscular junction. There is a strong evidence that an individual's genetic composition is an important predisposing factor for the development of the disease. To correlate HLA class II genotypes with thymic pathology in Mexican Mestizo patients who had been subjected to thymectomy. HLA class II genes were analyzed in 60 patients and in 99 healthy ethnically matched controls. Thymic hyperplasia, atrophy, thymoma, and normal histology were encountered in 56, 33, 8 and 2% of patients, respectively. HLA-DR11 was significantly increased in patients with thymoma compared with healthy controls (pC = 0.001, OR = 13.35, 95% CI 3.5-51.3), compared with the subgroup of hyperplasia patients (pC = 0.005, OR = 15.5, 95% CI 2.78-95.58) and with the atrophy subgroup (pC = 0.04, OR = 10.5, 95% CI 1.75-70.95). This study provides the evidence of an association between HLA class II alleles with clinical and genetic heterogeneity in myasthenia gravis, particularly in those with thymoma (HLA-DR11).     

Eosinophilia, myositis, and myasthenia gravis associated with a thymoma

Hypereosinophilia has been associated with a wide variety of systemic disorders, including myositis. Myositis develops in a minority of patients with myasthenia gravis associated with a thymoma. We present a patient who developed a life-threatening myopathy in which testing demonstrated the concurrence of hypereosinophilia, myositis, and myasthenia gravis associated with thymoma. Thymoma-associated T-cell abnormalities may well have contributed to this rare association. This case underscores the need to reevaluate constantly the presumed cause of clinical complaints, as more than one cause may be present.     

胸腺切除术治疗重症肌无力的疗效及其影响因素分析

目的总结行胸腺切除术的重症肌无力(MG)患者的疗效,并探讨影响近远期疗效的相关因素。方法回顾性分析作者医院收治的103例行胸腺切除术的MG患者的临床资料,采用卡方检验及Logistic回归分析可能影响疗效的因素。MG患者的近期及远期疗效分别用Monden、美国重症肌无力联盟(MGFA)分型进行评估。结果 103例患者中完成随访94例(91.26%),随访时间3个月~8年。近期疗效总有效率为60.2%,远期疗效总有效率为73.4%。发病年龄、性别、Osserman分型与术后近远期疗效均无相关(P0.05);病程(OR=0.240、95%CI:0.081~0.712,P0.05)、手术方式(OR=0.289、95%CI:0.110~0.757,P0.05)与近期疗效密切相关,是否合并胸腺瘤与远期疗效密切相关(OR=0.073、95%CI:0.009~0.575,P0.05)。结论病程越短,手术近期疗效越好;行胸腔镜手术较开胸手术能明显提高患者近期预后;MG不合并胸腺瘤者行胸腺切除术较合并胸腺瘤的患者更能从手术中获益。     

青少年起病的重症肌无力患者临床特点分析

目的分析青少年起病的重症肌无力(MG)患者的临床特点。方法回顾性分析2006-2013年作者医院神经内科住院的351例起病年龄≤18岁MG患者的临床资料,包括人口统计学(性别、年龄),临床特点(临床分型、起病症状、疾病转归、胸腺情况)和合并疾病(自身免疫性疾病)。结果青少年起病的MG患者发病年龄小于5岁者占45.9%,女性多见占53.6%。根据美国重症肌无力协会(myasthenia gravis foundation of America,MGFA)分型,Ⅰ型占80.3%,Ⅱa型占8.5%,Ⅱb型占9.1%,Ⅲa型占0.3%,Ⅲb型占1.4%,Ⅳb型占0.3%。由眼肌型MG(OMG)转化为全身型MG(GMG)患者39例(13.8%),主要诱发转化的因素为不规律用药或停药。诱发病情复发或加重的因素中以受凉多见,占63.6%。合并胸腺异常患者有60例,其中28例行胸腺切除术,术后病理分型:胸腺增生20例,胸腺瘤4例。合并有其他自身免疫性疾病共20例,其中甲状腺功能亢进占4.6%,甲状腺功能减低占0.6%,甲状腺囊肿占0.6%。共有6例患者发生过危象,其中5例发生肌无力危象者为由OMG转化为GMG患者。结论青少年MG患者有自己独特的临床特点:5岁之前发病更多见;诱发病情复发或加重的因素中以受凉多见;合并胸腺增生者多于合并胸腺瘤者;最常见的甲状腺功能异常为甲状腺功能亢进。     

Exacerbation of myasthenia gravis after removal of thymomas

It appeared from this prospective and non-randomized study, that the removal of thymomas in myasthenia gravis (MG) patients resulted in rapid exacerbation of the clinical severity of the disease and of anti-acetylcholine receptor antibodies titres, which peaked after about 300 days and continued for up to 2 years. Long-term follow-up after thymomectomy (mean duration ± SEM after surgery 5.5 ± 0.8 years) showed that the immunological and clinical state observed prior to surgery was eventually restored, but long-term benefit attributable to surgery could not be demonstrated. Non-thymoma MG cases, however, exhibited post-operative amelioration in clinical course and decreasing antibodies titres, both of which were already significant one year after surgery, and additional improvement was observed at the time of long-term follow-up (mean 4.3 ± 0.5 years). Furthermore, the prognosis for MG patients not operated on was also favourable. It is suggested that the occurrence of thymomas is linked to genetic factors and that neoplasia of the thymus may be part of immunoregulatory mechanisms with predominance of inhibition.     

伴胸腺异常重症肌无力患者对糖皮质激素治疗的反应性

目的探讨不伴其他自身免疫性疾病的重症肌无力(MG)患者胸腺异常对糖皮质激素治疗的反应性及其临床意义。方法回顾性分析2000-01—2014-12长海医院神经内科确诊并使用糖皮质激素治疗的86例MG不伴免疫性疾病患者的临床与生化检查结果资料,根据激素治疗后患者临床症状改善状况,将患者分为激素治疗敏感组与不敏感组,并比较两组间的临床及生化检查结果特征;根据是否伴有胸腺异常分为无胸腺异常组与伴胸腺异常组,比较两组间激素治疗的反应性;分析MG患者胸腺异常与激素治疗反应的相关性。结果激素治疗敏感组与不敏感组间患者性别、年龄50岁、病程3年、起病方式、上呼吸道感染、肠道泌尿道感染、累及肌群、血糖异常比例以及白细胞、C反应蛋白、红细胞沉降率水平比较差异无统计学意义(P0.05),两组间胸腺异常、血脂异常患者比例比较有统计学差异(P0.05);伴胸腺异常组与无胸腺异常组间激素治疗敏感者比例比较有统计学差异(χ~2=5.01,P=0.03);胸腺异常与激素治疗不敏感发生率呈正相关(r=0.237,P=0.03)。结论胸腺异常降低MG不伴免疫性疾病患者对激素治疗的疗效,认识两者之间的关系有助于MG患者的临床治疗评估及预后判断。     

Myasthenia gravis: clinical, immunological, and therapeutic advances

We give an update on clinical, immunological, and therapeutic advances in the field of myasthenia gravis, including a summary of suggested therapeutic recommendations.     

High anti-EBNA-1 IgG levels are associated with early-onset myasthenia gravis

Background: Myasthenia gravis (MG) is an autoimmune disorder mediated by antibodies against the acethylcholine receptor (AchR) of the neuromuscular junction in the majority of patients. Methods: Here, we examined IgG antibodies against the type 1 nuclear antigen of Epstein‐Barr virus (EBNA‐1) in the sera of 158 patients with MG compared to 184 healthy controls. Results: Although serum concentration in the sera was not different, high anti‐EBNA‐1 IgG titers (above 90th percentile of the normal values) were more common in the patients (26.6 vs. 16.3%, P = 0.024). In addition, high EBNA‐1 IgG levels occurred more frequently amongst the 94 patients with early‐onset myasthenia gravis (EOMG, 30.8%) as compared to the 64 patients with late‐onset disease (LOMG, 14.1%) (P = 0.021). Using multiple logistic regression, high serum concentration of the anti‐EBNA‐1 IgG antibodies was significantly associated with EOMG (OR: 3.17, P = 0.027), even after adjustment for sex, presence/absence of anti‐AchR antibodies and presence/absence of anti‐Titin antibodies. Out of 39 patients with EOMG, who underwent thymectomy, 18 patients (46%) had thymoma, 6 had thymic hyperplasia (15%), and 15 patients had thymic atrophy (39%); there was no difference comparing EBNA‐1 antibody titers in the sera. As no correlation was found between the titers of anti‐AchR, anti‐Titin, and EBNA‐1 antibodies, a dysregulated heterogeneous B‐cell response was unlikely to be responsible for the elevated levels of EBV‐associated antibody in patients. Conclusions: In summary, our data suggest that high levels of EBNA‐1 antibodies are more common in MG compared to healthy controls and are especially associated with EOMG.     

Myasthenia gravis accompanied by alopecia areata: clinical and immunogenetic aspects

The purpose of this study was to evaluate the clinical characteristics of patients who had both myasthenia gravis (MG) and alopecia areata (AA). Clinical information was retrospectively collected for 159 Japanese patients with MG. Human leukocyte antigen (HLA)-DQB1 and DRB1 alleles were determined by genotyping. Of 159 MG patients, six (3.7%) developed AA after the onset of MG and thymectomy. The prevalence of AA in MG patients was higher than that reported in Caucasians. The frequencies of bulbar involvement, myasthenic crisis, and thymoma were significantly higher in MG patients with AA than in those without (P = 0.007, 0.004, and 0.006, respectively). All but one patient with AA had advanced stage thymoma. Three patients with a severe form of AA (alopecia totalis) had additional autoimmune diseases: myocarditis, myositis, and pure red cell aplasia. DRB1*0901 and DQB1*0303 tended to be more frequently detected in the six MG patients with AA than in the 82 patients without it. In conclusion, a subset of MG patients who have severe neuromuscular symptoms and thymoma develop AA several years after thymectomy.     

Increased incidence of thymoma in Chinese myasthenia gravis: possible relationship with Epstein-Barr virus

Thymectomy was carried out for treatment of myasthenia gravis in 27 unselected Chinese patients and thymoma was found in 13 of them. This 48% incidence of thymomas is two to three times greater than in Japanese and European patients, respectively. The reason for the higher incidence of thymomas observed in Chinese patients may be related to the presence of the Epstein-Barr virus genome in thymoma. Furthermore, all of the thymomas in our patients were lymphoepithelial and histologically resemble nasopharyngeal carcinoma and undifferentiated carcinoma of the salivary gland. Both these tumours are closely linked to the Epstein-Barr virus and in Hong Kong, nasopharyngeal carcinoma is the third commonest cause of death from malignancy. We recommend early thymectomy for patients with myasthenia gravis particularly in geographical areas where there is a high incidence of nasopharyngeal carcinoma and undifferentiated carcinoma of the salivary gland.     

Impact of screening with thyroid ultrasonography in myasthenia gravis patients

Maruyama E, Minami N, Niino M, Fujiki N, Doi S, Watanabe M, Shima K, Kikuchi S, Sasaki H. Impact of screening with thyroid ultrasonography in patients with myasthenia gravis.
Acta Neurol Scand: 2012: 125: 398–402.
© 2011 John Wiley & Sons A/S. Objectives – This study was conducted to screen thyroid abnormality evaluated with ultrasonography (US) in patients with myasthenia gravis (MG) and investigate further when malignancy is suspected. Methods – Thyroid screening using US was conducted in 162 patients with MG. In cases where malignancy was suspected, further investigations were performed. Results – Abnormal US findings were detected in 125 of 162 patients with MG (72 patients with nodules, 74 patients with cysts, 27 patients with diffuse findings such as enlargement, atrophy, a hypoechoic pattern or a heterogenous echoic pattern, and 28 patients with calcification). From among these 125 subjects, 30 patients underwent further examinations such as needle aspiration cytology. As a result, six patients (3.7% of 162 cases) were positive for papillary carcinoma. The size of the carcinoma in three patients was <10 mm, yet the stage of thyroid carcinomas was high (stage III or IVa) in all six cases. Conclusions – Our data suggest that the prevalence of thyroid carcinoma in cases of MG may be higher than that of the general population. Furthermore, in patients with MG, there is a possibility that the stage of the carcinoma is higher even when the carcinoma is of a very small size. Patients with MG, when diagnosed, should be advised to undergo US screening of the thyroid because most cases of thyroid carcinoma are highly curable.