Myasthenic crisis

Myasthenic crisis is a serious occurrence, affecting up to 27% of patients with myasthenia gravis. In the approach to the patient with myasthenic crisis, (1) the diagnosis of myasthenia gravis is confirmed; (2) respiratory failure is evaluated and treated in the intensive care unit, while potential precipitating factors are identified and managed; (3) immunomodulatory treatment is initiated; and (4) complications are avoided or managed promptly. The mortality rate should be 5% or less, with the elderly being most vulnerable.     

Propofol or sevoflurane anesthesia without muscle relaxants for thymectomy in myasthenia gravis

Background Myasthenia gravis is a challenging clinical condition due to its neuromuscular involvement. We sought to compare two non-muscle relaxant anesthetic techniques in patients undergoing trans-sternal thymectomy, evaluating the intra and postoperative conditions including extubation in the operating room. Methods Eight consecutive myasthenic patients undergoing trans-sternal thymectomy were prospectively randomized into two groups: propofol and sevoflurane. In both groups anesthesia was induced with propofol (2mg. Kg⁻¹) and intubation performed after topical anesthesia of the airway with lignocaine. Anesthesia was maintained in the propofol group (4 patients) with continuous propofol infusion (3–10 mg. Kg⁻¹., hr⁻¹) with oxygen and nitrous oxide and in the sevoflurane group (4 patients), with sevoflurane (end tidal 1–1.5%) in oxygen and nitrous oxide. Fentanyl was used for analgesia in both the groups. Intubating conditions, haemodynamic changes, neuromuscular transmission along with postoperative intensive care unit stay were evaluated. Data were evaluated using ANOVA, Chi-square test and Student'st test. Results Intubating conditions were good in all patients. There were no significant haemodynamic changes. All patients were extubated in the operating room and none had to be re-intubated for postoperative respiratory depression. Neuromuscular transmission showed minimal changes and at the end of the procedure the recovery was complete in all the patients. There were no other significant differences between the two groups studied. Conclusion These two anesthetic techniques allow early extubation of myasthenic patients in the operating room.     

Masticatory performance in patients with myasthenia gravis

Masticatory muscle electromyograms (EMGs) were recorded while patients with bulbar myasthenia gravis chewed artificial food and compared with those of patients with ocular myasthenia gravis, patients in clinical remission who had previously suffered from bulbar myasthenia gravis and healthy individuals. Masticatory performance and EMGs were significantly smaller in the bulbar group. There were no indications of subclinical masticatory muscle weakness in patients with bulbar myasthenia gravis in remission and in patients with ocular myasthenia gravis. Patients with bulbar myasthenia gravis barely compensated for muscular weakness by chewing at a higher percentage of their maximal EMG. These quantitative findings, when combined with subjective reports of masticatory muscle weakness, show that a need to support the jaw is characteristic of patients with bulbar myasthenia gravis who produce low EMG activity.     

Matched-pair comparison of three different approaches for thymectomy in myasthenia gravis

Background: Because of the lack of evidence-based data comparing different techniques for thymectomy (Thx), a matched-pair study was conducted to evaluate the role of thoracoscopic Thx (tThx) more objectively. Methods: Of 182 patients who underwent Thx, 3 groups according to the operation technique were matched for myasthenia gravis (MG) without thymoma, age, gender, and severity of MG. Twenty patients each who had Thx through anterolateral thoracotomy (aThx), extended median sternotomy (sThx), and tThx were compared for length of operation, postoperative morbidity, complete remission, quantification of improvement of MG, and cosmetic results. Results: Complete tThx required 197 ± 35 min as compared to 113 ± 43 min for sThx and 82 ± 27 min for aThx (P < 0.001). With zero mortality the overall postoperative morbidity rate was 25% for sThx versus 15% for aThx and 5% for tThx (P < 0.05). There was no difference in complete remission of MG. The median activities of daily living (ADL) scores improved by 6.0 (1–19) after tThx, 5.5 (2–4) after sThx, and 7.5 (0–12) after aThx. Best cosmetic results were achieved after tThx. Conclusions: There was adequate cumulative medium-term improvement of MG and less postoperative morbidity after tThx, which may become the preferred technique for Thx.     

Breakage of tolerance to hidden cytoplasmic epitopes of the acetylcholine receptor in experimental autoimmune myasthenia gravis

The acetylcholine receptor (AChR) is the major autoantigen in the antibody-mediated disease myasthenia gravis (MG) and its animal model experimental autoimmune myasthenia gravis (EAMG). This study demonstrates that rats immunized with a recombinant fragment corresponding to the normally exposed extracellular region of the rat AChR -subunit first develop antibodies to the injected extracellular portion only, but later develop antibodies to intracellular cytoplasmic epitopes of AChR. The presence of autoantibodies to intracellular epitopes seems to be correlated with development of clinical signs of disease. We propose that a similar process of epitope spreading may take place in the natural course of myasthenia.     

流式细胞术检测重症肌无力患者调节性T细胞变化

目的：探讨并发胸腺疾病的重症肌无力患者的外周血和胸腺中调节性T细胞变化。方法：采用流式细胞仪多参数（三标CD4、CD25和Foxp3）逐层分析法分析并发胸腺疾病的重症肌无力患者的外周血和胸腺中调节性T细胞比例。结果：正常人、MG并胸腺增生者和MG并胸腺瘤者外周血中CD4＋阳性细胞中调节性T细胞比例差别无统计学意义（F=0.095,P=0.910）,胸腺中CD4＋阳性细胞中调节性T细胞比例差别有统计学意义（F=16.162,P〈0.001）。结论：调节性T细胞数量减少或功能异常在MG中起重要作用。用流式细胞仪多参数逐层分析法是淋巴细胞亚型分析的重要方法。     

小儿重症肌无力危象

目的 研究小儿重症肌无力危象的临床特点、诊断标准及治疗方法。方法 对4例重症肌无力危象患儿作一回顾性分析。结果 4例为急性起病,分别表现为两侧眼睑下垂,眼球活动受限,吞咽困难、四肢肌力、肌张力减弱。结论 小儿重症肌无力的病史和新斯的明试验阳性是诊断本病的重要依据。使用溴化吡啶斯的明和泼尼松可防止危象再发生。     

中西医结合抢救38例重症肌无力危象临床分析

目的研究中西医结合在重症肌无力危象中的应用价值。方法选择2009年4月一2011年12月我院收治的重症肌无力危象患者76例，按照不同的治疗方法分成研究组（38例）与对照组（38例），研究组运用中西医结合方案治疗，对照组采用常规性治疗方案。比较两组治疗效果。结果研究组患者与对照组患者在治疗前、治疗后的绝对评分分值比较差异有统计学意义（P〈0．01），研究组患者与对照组患者危象持续时间比较差异有统计学意义（P〈0．01）。研究组的总有效率为89．5％，显著优于对照组（P〈0．05）。结论中西医结合治疗在重症肌无力危象中应用价值较高，可以较好地改善预后，降低死亡率。     

Anti-idiotypic antibodies to anti-acetylcholinereceptor antibody: Characterization by ELISA and immunoprecipitation assays

The idiotype network is important both as a means of autoregulation of immune mechanisms and a potential tool for manipulation of abnormal responses. In the autoimmune disease myasthenia gravis the acetylcholine receptor (AChR) is the target of an aberrant immune response. In this study we compare 2 widely used methods of antibody determination--immunoprecipitation radioimmunoassay (IPRA) and enzyme-linked immunoassay (ELISA)--for their ability to detect both anti-AChR antibodies (polyclonal and monoclonal) and anti-idiotypic antibodies raised against polyclonal anti-AChR antibodies. Although the IPRA is considerably more sensitive for the detection of monoclonal anti-AChR antibodies, the 2 methods produce similar results in the detection of anti-idiotypic antibodies to the anti-AChR immune response. The 2 techniques also demonstrated specificity of the reagents for idiotypes associated with the anti-AChR response and absence of effect on an idiotype associated with the control antigen, ovalbumin. The results demonstrate that the idiotypic repertoire of the polyclonal anti-AChR response in C57B1/6 mice is sufficiently restricted that antigen-specific blocking anti-idiotypic antibodies can be raised in rabbits by immunization with anti-AChR antibodies.     

重症肌无力患者血清Ryanodine受体抗体与临床的相关性研究

目的 探讨血清Ryanodine受体抗体(RyR-Ab)与重症肌无力(MG)的关系.方法 应用ELISA和Western blot法分别检测81例MG患者、45例非MG神经系统其他疾病(NMG)患者和50例健康对照者(HC)血清中RyR-Ab水平.结果 ELISA法显示:MG组RyR-Ab阳性率为23.4%.明显高于HC组和NMG组(均为阴性),差异有统计学意义(P<0.05);MG伴胸腺瘤(MGT)组阳性率最高(77.2%),MG伴胸腺萎缩(MGA)者次之(14.2%),MG伴胸腺增生(MGH)者为6.6%;而且RyR-Ab水平与肌无力的严重程度成正相关(r=0.547.P<0.05);RyR-Ab诊断MGT的敏感性(77.2%)低于胸腺CT(88.2%),但特异性(91%)高于后者(72.2%),差异有统计学意义(P<0.05).Westemblot法显示:MGT组RyR-Ab阳性条带检出率最高(81.8%),明显高于非胸腺瘤MG(NTMG)组(4.5%)和NMG组(0),差异有统计学意义(P<0.05).结论 RyR-Ab阳性多见于MGT,检测RyR-Ab可以弥补影像学的不足,有助于诊断MGT和评估病情.