Thymectomy for myasthenia gravis: 12-year experience

Thymectomy has been shown to be effective in the treatment of myasthenia gravis. The logical goal of operation is the complete removal of the thymus, but there is no consensus on the selection criteria of patients for surgery and the choice of surgical approach. We retrospectively reviewed 56 patients with myasthenia gravis who had been treated surgically by transsternal radical thymectomy between January 1990 and March 2002. The patients were symptomatically grouped according to the modified Osserman clinical classification. There was 1 hospital death, and 53 patients had been followed up for between 1 month and 12 years. Improvement after thymectomy was observed in 1 of 4 patients (25%) in Osserman group I, 25 of 34 patients (74%) in Osserman group IIA, and 16 of 18 patients (89%) in combined Osserman groups IIB and IIC. Transsternal radical thymectomy is an effective therapy for myasthenia gravis. Sustained improvement is achievable in female patients with moderate to severe symptoms and in patients with thymic hyperplasia.     

Prognostic factors for conversion to generalization in ocular myasthenia gravis

Patients with ocular myasthenia gravis (OMG) are frequently treated to prevent the development of generalized myasthenia gravis (GMG). This retrospective cohort study aimed to assess prognostic factors associated with conversion to GMG.We analyzed the time from the onset of OMG symptoms to GMG in relation to demographic variables, clinical findings, initial investigation results, and treatment regimens using Kaplan–Meier survival curves and multivariate Cox proportional regression analysis.Of 115 patients diagnosed with OMG (median follow-up time, 2.9 years), 28 (30.4%) developed GMG. The 2-year probability of GMG conversion was 23.7%. Patients with thymic abnormalities and a positive response to repetitive facial nerve stimulation had a significantly higher risk than those with negative results (hazard ratios [HR] 4.28, P < .001 and HR 3.84, P = .04, respectively). Treatment with immunosuppressants was found to be a preventive factor for secondary generalization (HR 0.36, P = .02).Patients with OMG had a low risk of developing GMG. Immunosuppressive treatments may mitigate disease progression. Chest imaging and repetitive nerve stimulation should be routinely performed to assess the risk of generalization.     

Thymectomy in the treatment of myasthenia

Thymectomy has been performed in 69 patients, 58 females and 11 males, age range 14 to 70 years, with a maximum in females between 20 to 30 years. Twenty-seven percent of the patients were older than 40 years. Considerable improvement resulting from remission and partial remission occurred in 89% of females and in about 50% of males, the figure for thymomatous myasthenia was about 65% in the first year after thymectomy. In the following years, improvements increased partially and the number of remissions rose as well. By chance the duration of the disease was longer than 6 years in 20% of our patients and in these a benefit from thymectomy was also found. There were 7 early deaths and 4 late deaths. Thymectomy cannot be called a cure but is an essential part of the whole treatment procedure of myasthenia comprising the administration of anticholinesterase and especially immunosuppressive agents. It was found difficult to estimate the effect of any single measure in this retrospective study by the major benefit of thymectomy is seen in initiating remissions or at least considerable improvements. Indication for operation is thought to be present in progressive myasthenia, acute or chronic, and thymoma, provided that the patient has reached an optimal condition preoperatively by adequate anticholinesterase adjustment, neurophysiological control and immunosuppressive treatment. Thymectomy is not an emergency operation and should be carefully planned. Since relapses after thymectomy are not rare, a careful neurological long-term follow-up appears obligatory.     

Prognosis of patients with myasthenia gravis

AIM: To study the correlation between therapy and outcome of patients with late adult onset and ocular type myasthenia gravis (MG). METHODS: The 58 MG patients admitted to our hospitals from 1991 to 2003 were classified into juvenile (younger than 20), early adult onset (20-64) and late adult onset (65 or older) groups, or also ocular and generalized types. We evaluated their therapeutic outcomes. RESULTS: The late adult onset group consisted of 11 patients, classified as 4 ocular and 7 generalized types. There were more women than men in both the late and early adult onset groups. Anti-acetylcholine receptor (anti-AchR) antibodies were positive in all patients. Four patients had thymus lesions. Ten patients received treatment as follows: steroid therapy in 6, thymectomy in 4 and only choline-esterase (ChE) inhibitor therapy in 4 patients. However 4 patients worsened after treatment because of inadequate steroid therapy, 2 of whom experienced myasthenic crisis. On the other hand 21 patients were ocular type, of whom anti-AchR antibodies were positive in 12. They received treatments of the 21, steroid therapy was given to 12, thymectomy was performed in 4 and only ChE inhibitor therapy was given to 8 patients. One ocular type patient progressed to the generalized type. Six of 16 improved patients showed distinct recovery. CONCLUSION: In the late adult onset group careful assessment concerning timings of administration and reduction of steroid are required to avoid side effects and complications. One ocular type patient progressed to the generalized type and most patients had a good outcome, which might be related to steroid therapy.     

Subcostal thoracoscopic extended thymectomy for patients with myasthenia gravis

Background

Extended thymectomy is indicated for patients with myasthenia gravis (MG) when drug-resistance or dependence is seen. We have employed a technique for subcostal thoracoscopic extended thymectomy (STET) on patients with MG.

Methods

Clinical data of 15 eligible patients who underwent STET in our department from February 2015 to November 2015 by the same surgical team were retrospectively analyzed. The operation time, blood loss, duration of postoperative hospital stay, thoracic drainage periods were concerned.

Results

All the surgeries were finished successfully without conversion to sternotomy. Mean operation time was 157.53±40.31 min (range, 73–275 min). Mean blood loss was 56.33±7.07 mL (range, 10–200 mL). Mean pleural drainage volume in the first 24 hours was 72.67±17.68 mL (range, 0–250 mL). Mean postoperative thoracic drainage periods were 1.20±0.71 days (range, 0–3 days). Mean duration of postoperative hospital stay was 6.13±0.71 days (range, 3–22 days).

Conclusions

This procedure showed satisfactory results for patients with MG. Moreover, the STET approach is more easily for surgeons to fully reveal the bilateral phrenic nerve and the upper thymic poles. We believe that STET is a satisfactory procedure for performing extended thymectomy in well selected patients.     

老年人重症肌无力临床研究

目的本文旨在探讨老年人重症肌无力（MG）的临床特点。方法将本院12年间诊治的458例MG,根据发病年龄分为小儿组（≤14岁）、成年组（15～59岁）及老年组（≥60岁）。回顾性分析各组病例的首发症状及其演变、合并症以及误诊情况,以明确老年MG患者的临床特点。结果老年组MG在整个MG人群中构成比小,男性发病者较多见,以延髓症状首发者多见,演变为呼吸困难者比例高,合并胸腺瘤者多而合并其他自体免疫病者少,以延髓症状首发而误诊为脑血管病者多见,病死率高,但死于肌无力危象者少,常死于多种并发症。结论掌握老年MG患者的临床特点有助于指导临床的诊断和治疗。     

Pericarditis in myasthenia gravis

Myasthenia gravis is an autoimmune disorder with antibodies to the acetylcholine receptors (Ach R) in skeletal muscles. Myocardial involvement can present as a myocarditis or with arrhythmias. To our knowledge, there is no documentation in the literature of pericardial involvement in myasthenia gravis. We report the presence of pericardial effusion and atrioventricular conduction block in a patient with myasthenia gravis that responded appropriately to immunosuppressive therapy and plasma exchanges.     

Control of breathing in patients with myasthenia gravis.

Control of breathing has seldom been investigated in patients with myasthenia gravis (MG). We evaluated lung volumes and respiratory muscle strength by measuring maximal inspiratory (MIP) and expiratory (MEP) pressures in 12 patients with moderate generalized (IIb) MG before and after an orally administered therapeutic dose (120 mg) of Mestinon, and in 11 age- and sex-matched normal subjects. Breathing pattern, mouth occlusion pressure (P0.1), and surface electromyographic activity of the diaphragm (EMGd) and intercostal (EMGint) muscles were evaluated during both room-air breathing and hypercapnic rebreathing. Before Mestinon, patients exhibited a slight decrease in VC, and normal TLC and FEV1/VC ratio. Compared with the normal control group, patients also exhibited respiratory muscle weakness (marked decrease in MIP and MEP; p less than 0.001 for both), and more rapid and shallower breathing (RSB): lower tidal volume (VT), inspiratory time (TI), expiratory time (TE), and greater respiratory frequency (f); mean inspiratory flow (VT/TI) and P0.1 were slightly supernormal, whereas both EMGd and EMGint were significantly higher in patients. During hypercapnic rebreathing, ventilation (VE) (p less than 0.001), VT (p less than 0.001), VT/TI, (p less than 0.003), P0.1 (p less than 0.003), and EMGd (p less than 0.001) response slopes to increasing PCO2 were found to be lower, whereas EMGint response slope was normal. At 60 mm Hg of PCO2 in the two groups the difference in terms of breathing pattern, P0.1, and EMGd were similar to that observed during room-air breathing. After Mestinon, VC (p less than 0.005), MIP (p less than 0.02), and MEP (p less than 0.01) significantly increased, whereas spontaneous breathing remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sevoflurane for trans-sternal thymectomy in myasthenia gravis

Myasthenic gravis (MG) is an autoimmune disease associated with acetylcholine receptor deficiency. Patients with MG exhibit increased sensitivity to non-depolarising muscle relaxants. In an attempt to avoid neuromuscular blockers, we used sevoflurane in two myasthenic patients undergoing trans-sternal thymectomy. Inhalation of 8% sevoflurane in oxygen using vital capacity technique produced rapid, pleasant and smooth induction and provided good tracheal intubating conditions. In both patients anaesthesia was maintained with 1.5-2% end-tidal concentration of sevoflurane and nitrous oxide in oxygen without adjunctive neuromuscular blocking agents. There were minimal changes in cardiovascular variables and recovery was faster. It is suggested that sevoflurane may be the main anaesthetic for both induction and maintenance in myasthenic patients undergoing trans-sternal thymectomy.     

Microscopic-sized "microthymoma" in patients with myasthenia gravis

BACKGROUND: In 2005, Cheuk et al reported two patients with microscopic-sized thymomas and proposed the term microthymoma to distinguish it from the nodular hyperplasia of thymic epithelium, so-called microscopic thymoma. Here, we present microthymomas that were found in 196 patients with myasthenia gravis (MG) who had undergone thymectomy. MATERIALS AND METHODS: Thymic tissues in 196 patients with MG who underwent thymectomy or thymothymomectomy were examined. Of these patients, 73 patients had thymoma indicated by CT before surgery, and the other 123 patients had no mediastinal tumors. From the resected thymic tissues, an average of 14 hematoxylin-eosin-stained sections (range, 4 to 55 sections) were prepared for microscopic examination. The histologic type of the thymoma was classified according to the World Health Organization (WHO) classification. RESULTS: From the 196 patients, we found three microthymomas in 3 patients (1.5%). While these three tumors could not be seen grossly in pathology section, they were found microscopically (range, 2 to 4 mm). The histologic subtype according to the WHO classification system was B1 in one patient and B2 in two patients. CONCLUSION: Microthymoma was found in 3 of 196 patients (1.5%) with MG. Microthymoma might exist in thymus of patients with MG, even in patients who have no thymoma indicated by CT.     

Electrocardiographic findings in 24 patients with myasthenia gravis.

Twenty four myasthenia gravis patients, 14 females and 10 males, aged between 5 and 65 years (average 29) were studied electrocardiographically. The abnormalities found in the ECG were: prolonged "Q-T" intervals (10 cases, 44.1%), sinus tachycardias (5 cases, 20.8%), sinus arrhythmias (5 cases, 20.8%), right bundle branch block (4 cases, 16.6%), and non-specific "T" wave changes (2 cases, 8.3%). Among our 24 patients with myasthenia gravis, in contrast to previous reports, only two had non-specific "T" wave abnormalities. But prolonged "Q-T" intervals, right bundle branch block, sinus tachycardias and sinus arrhythmias, when compared to normal population incidence, were found to be quite significant. In pathogenesis, primary myocardial histo-pathological abnormalities, and the role of extracardiac factors in producing the changes were discussed.     

Video-assisted thoracoscopic thymectomy for myasthenia gravis

Background: Thymectomy is an effective, but radical therapy for myasthenia. Video‐assisted thoracic surgery (VATS) may allow a minimally invasive altern­ative to the standard sternotomy approach. Aims: To audit prospectively the outcome of VATS thymectomy for myasthenia gravis in a unit specializing in advanced VATS techniques. Methods: Twenty‐six patients underwent VATS thymectomy between 1997 and 2001. Most underwent preoperative plasma exchange therapy. Seventeen women and nine men with a median age of 36 years (range 17?71 years) had a right‐sided VATS approach to remove all anterior mediastinal fat and thymic tissue. Results: There was no perioperative mortality and all procedures were concluded successfully, with one patient requiring sternotomy. Twenty‐five patients were extubated in theatre and one patient required 17 h of assisted ventilation . The other significant complication was a diathermy injury to the phrenic nerve, which recovered. Median postoperative stay was 4 days (range 2?6 days), with median postoper­ative chest drainage for 2 days (range 1?3 days). Three patients had progression of disease postoperatively. The remainder were asymptomatic (7), improved (14) or stable (2). Conclusion: In a dedicated unit with neurological and intensive care support, VATS thymectomy is a safe, effective method of obtaining remission or improvement in myasthenia gravis (MG). While achieving the same surgical goal, this approach offers advantages of improved cosmesis, shorter recovery time and minimal chest wall disruption over the gold standard of sternotomy. Better patient acceptance of this minimally invasive technique may result in wider application of the benefits of thymectomy in MG. (Intern Med J 2002; 32: 367?371)