Thymectomy In Non-thymomatous Myasthenia Gravis Research Articles

Attitudes and Beliefs Toward Thymectomy in the Myasthenia Gravis Patient Registry.

To evaluate patient attitudes and beliefs toward thymectomy for myasthenia gravis (MG). The Myasthenia Gravis Foundation of America administered a questionnaire to the MG Patient Registry, an ongoing longitudinal survey of adult MG patients. Questions assessed reasons for or against thymectomy and how hypothetical scenarios would have affected their decision. Of 621 respondents, 190 (31%) reported a history of thymectomy. Of those who underwent thymectomy for nonthymomatous MG, 97 (51.6%) ranked symptom improvement as most important and 100 (53.2%) ranked reducing medication as least important. Among 431 nonthymectomy patients, the most frequent reason for not undergoing thymectomy was that their doctor did not discuss it (152 of 431 = 35.2%) and 235 (56.8%) said that they would have considered it more strongly if their doctor spent more time discussing it. Thymectomies are motivated more by symptoms than by medication, and a lack of neurologist discussion is the most common barrier to thymectomy.

Outcomes after thymectomy in non-thymomatous myasthenia gravis.

Guidelines by the myasthenia gravis (MG) Foundation of America suggest patients aged 18 to 50 years with non-thymomatous myasthenia gravis (NTMG) benefit from thymectomy. Our objective was to investigate utilization of thymectomy in NTMG patients outside the confines of a clinical trial. From the Optum de-identified Clinformatics Data Mart Claims Database (2007 to 2021), we identified patients diagnosed with MG between 18-50 years old. We then selected patients who received a thymectomy within 12 months of MG diagnosis. Outcomes included use of steroids, non-steroidal immunosuppressive agents (NSIS), and rescue therapy (plasmapheresis or intravenous immunoglobulin), as well as NTMG-related emergency department (ED) visits and hospital admissions. These outcomes were compared in the 6-months before and after thymectomy. A total of 1,298 patients met our inclusion criteria, of whom 45 (3.47%) received a thymectomy, performed via minimally invasive surgery in 53.3% of cases (n=24). In comparing the pre- to post-operative period, we noted that steroid use increased (53.33% to 66.67%, P=0.034), NSIS use remained stable, and use of rescue therapy decreased (44.44% to 24.44%, P=0.007). Costs associated with steroid and NSIS use remained stable. However, the mean costs of rescue therapy decreased (from $13,243.98 to $8,486.26, P=0.035). Hospital admissions and ED visits related to NTMG remained stable. There were 2 readmissions within 90 days (4.44%) associated with thymectomy. Patients with NTMG undergoing thymectomy experienced less need for rescue therapy following resection, albeit with increased rates of steroid prescriptions. Thymectomy is infrequently performed in this patient population despite acceptable postsurgical outcomes.

The short and long-term effects of open vs minimally invasive thymectomy in myasthenia gravis patients: a systematic review and meta-analysis.

Thymectomy has been utilized as a treatment for Myasthenia Gravis (MG) for many decades, with both open and minimally invasive surgical (MIS) techniques currently used. Although MIS has shown improved short-term results, long-term effects remain uncertain. This systematic review and meta-analysis aim to compare the post-operative and long-term outcomes of MIS versus open thymectomy in MG patients. MEDLINE, EMBASE and CENTRAL databases were searched from inception till January 2022 for keywords related to MG and open or MIS thymectomy. Primary outcome was complete stable remission (CSR), and secondary outcomes were clinical improvement, complications, length of stay, operation time, and blood loss. Grading of recommendations, assessment, development, and evaluation was used to assess the certainty of evidence. 26 studies with 3588 patients were included in the analysis. At 1, 3 and 5years, there was no statistical difference noted in CSR between open versus MIS thymectomy. However, CSR was improved at 1year for MIS thymectomy in non-thymomatous MG (P = 0.03). There was no significant difference in rates of partial clinical improvement between techniques at 1-year. Although analyses on length of hospital stay and blood loss showed improvement following MIS thymectomy, operative time was shorter for open thymectomy. This is the first systematic review and meta-analysis assessing long-term effects of MIS versus open thymectomy in MG patients. Given the lack of significant differences noted, either MIS or open thymectomy can be performed, based on surgeon preference. Further high-level, long-term research should be conducted to determine the benefit of each technique.

Ectopic germinal centers in the thymus accurately predict prognosis of myasthenia gravis after thymectomy

AbstractThe ability of thymic histopathology to predict the long-term impact of thymectomy in non-thymomatous myasthenia gravis (NTMG) is mainly uncharted. We applied digital pathology to quantitatively characterize differences of thymic histology between early-onset (EOMG) and late-onset MG (LOMG) and to investigate the role of thymic changes for thymectomy outcomes in MG. We analyzed 83 thymic H&E slides from thymectomized NTMG patients, of which 69 had EOMG and 14 LOMG, using digital pathology open-access software QuPath. We compared the results to the retrospectively assessed clinical outcome at two years after thymectomy and at the last follow-up visit where complete stable remission and minimal use of medication were primary outcomes. The automated annotation pipeline was an effective and reliable way to analyze thymic H&E samples compared to manual annotation with mean intraclass correlation of 0.80. The ratio of thymic tissue to stroma and fat was increased in EOMG compared to LOMG (p = 8.7e-07), whereas no difference was observed in the ratio of medulla to cortex between these subtypes. AChRAb seropositivity correlated with the number of ectopic germinal centers (eGC; p = 0.00067) but not with other histological areas. Patients with an increased number of eGCs had better post-thymectomy outcomes at two years after thymectomy (p = 0.0035) and at the last follow-up (p = 0.0267). ROC analysis showed that eGC area predicts thymectomy outcome in EOMG with an AUC of 0.79. Digital pathology can thus help in providing a predictive tool to the clinician, the eGC number, to guide the post-thymectomy treatment decisions in EOMG patients.

Robotic-assisted minimally invasive thymectomy for myasthenia gravis with thymoma.

Robotic-assisted minimally invasive thymectomy for myasthenia gravis with thymoma.

Thymectomy for non-thymomatous myasthenia gravis: Short and long term outcomes, a single-center 10 years' experience

BackgroundMyasthenia gravis (MG) is an auto-immune disorder characterized by the production of abnormal antibodies to the acetylcholine receptors at the neuromuscular junction. Radical thymectomy in many forms of MG may lead to clinical improvement in 70–80% of cases. Our objectives were to demonstrate our short and long-term results of radical trans-sternal thymectomy. Patients and methodsRetrospective analysis of prospectively collected data from 48 consecutive patients with non-thymomatous MG, managed over 10 years. All patients with thymomatous MG were excluded. The myasthenia gravis activities of daily living (MG-ADL) scoring performed for all patients and the stage of disease determined by the Myasthenia Gravis Foundation of America (MGFA) classification. The primary endpoint of this study was to evaluate early first 30 days postoperative outcomes and the secondary endpoint was to determine complete stable remission, time of pharmacological remission, and decreasing MG-ADL scoring over 5 years follow-up. ResultsTotally, 48 patients included: 41 females (85.4%) and 7 males (14.5%). Generalized muscle weakness, shortness of breath, and easy fatigability were the most common presenting features. During 5 years follow up, 38 patients (79.1%) had decreased their medication dose. Time of pharmacological remission started (6–60) months. Complete stable remission (CSR) achieved in 44 patients (91.6%) over 60 months. Post-operative MG-ADL levels ranged between (12–24) scores, at the end of the follow-up period decrease to less than 10 scores. ConclusionRadical trans-sternal thymectomy for non-thymomatous MG is an effective and well-tolerated procedure that is associated with significant clinical improvement in the majority of patients.

Thymectomy in Non-Thymomatous Myasthenia Gravis: Does An RCT Solve The 75-Year-Old Controversy?

The role of thymectomy in thymomatous myasthenia gravis (MG) is unambiguous. However, its role in non-thymomatous MG (NTMG) remains debatable. The evidence till date is not robust. In this short review, we try to see the pros and cons of thymectomy in NTMG and critically appraise the evidence available till date.

AB011. Surgical management of myasthenia gravis

: Since Ferdinand Sauerbruch performed a subtotal thyroidectomy with concomitant subtotal thymectomy with a subsequent clinical improvement of myasthenia gravis (MG) in 1912, surgeons try to improve the approaches, extend and strategy of thymectomies. The effector mechanism of MG are autoantibodies which target the neuro-muscular junction. In the 1970s the detection of acetylcholine receptor antibodies supported the theory of an autoimmune disease. In the 2000s the muscle specific kinase was identified as an additional autoantibody. Just recently low-density lipo-protein receptor related protein 4 (LRP4) was postulated to be a potential autoantibody target. The interaction of these antibodies leads to numerous effects on the transmission of the electric signal from the nerve to the muscle cells with a complex interaction of different cells of the immune response originating from the thymus gland. These interactions are evident in non thymomatous MG as well as MG with thymoma. In latter, additional paraneoplastic mechanism are discussed. Interestingly, the incidence of MG is highest in AB and B2 thymoma patients, of whom about one quarter suffer from paraneoplastic MG. Whereas the indication for thymectomy is clear in cases of thymoma plus MG, the indication for thymectomy for non-thymomatous MG remains in parts controversial. Up to 2016 the evidence base for this indication was as low as level III. In 2016 Wolfe et al. published a first of its kind land mark RCT on thymectomy in MG. Although methodology was controversial in some areas it was the first RCT to show the positive effects of this procedure in MG. The primary outcomes were the time-weighted average quantitative Myasthenia Gravis score over a 3-year period and the time-weighted average required dose of prednisone over a 3-year period. In a follow up publication, the study group could show a continuous benefit in a 5-year follow up. The findings of these RCTs support the conclusion of many other non-randomized trial or retrospective analysis. Nevertheless, many aspects of modern thymic surgery proclaimed remain unclear and need further high-level evidence. This includes the surgical approach and the extent of resection, as well as the definition of the patient cohort benefiting the most from the procedure. Although the Wolfe study investigates only open transsternal approaches, with a patient recruitment period of 2006 to 2012, many surgeons believe that the modern minimal invasive approaches are at least equal in the treatment effect with fewer complications. These minimal invasive approaches include extended transcervical approaches, video-assisted thoracoscopic surgery (VATS) approaches either in a classic fashion transintercostal or subxiphoid as well as robotic approaches. All these approaches proved feasible and safe in expert hands but failed to show superiority in a board use. The extend of the resection in the study was defined as en bloc resection of all mediastinal tissue that could anatomically contain gross or microscopic thymus (or both). In many publications this kind of a resection is called an extended thymectomy although the terms thymectomy and extended thymectomy are used inconsistently throughout the literature. Many surgeons believe that the removal of all mediastinal tissue is indicated, since many studies showed ectopic thymic tissue outside the distinct gland and spread in mediastinal fat. But there is no level II or higher evidence supporting this. A higher incidence of phrenic nerve injuries with consecutive diaphragmatic paralysis might be associated with this extended resection, resulting in serve pulmonary complication in MG patients, as well as other rare but major complications like vessel injuries. Regarding the patient cohort suitable for surgical treatment the Wolfe study included patients with a disease onset of less than 3 years, an age of 18 to 60 years, a serum acetylcholine-receptor-antibody level of more than 1.00 nmol per liter (elevated levels of 0.50 to 0.99 nmol per liter were accepted if the diagnosis was confirmed by a positive edrophonium test, abnormal repetitive nerve stimulation, or abnormal single-fiber electromyography), and a Myasthenia Gravis Foundation of America clinical classification of II to IV. Participants could be taking appropriate anticholinesterase therapy with or without oral glucocorticoids. Exclusion criteria were thymoma on computed tomography or magnetic resonance imaging of the chest. All these criteria go inline with the guidelines for this disease prior to the study and have not changed since then. Again, only weak evidence supports the criteria. We conclude on the basis of available evidence that surgery for MG is beneficial for sero-positive patient between 18–60 years with a short duration of the disease. In the daily practice of the authors the robotic extended thymectomy is used routinely. In addition, we offer this operation to AChR-sero-negative patients after an in-depth informed consent process.

PC03.05 Debate on Standard Surgical Approaches - Open Thymectomy

PC03.05 Debate on Standard Surgical Approaches - Open Thymectomy

Present validity of “maximal” thymectomy in the treatment of myasthenia gravis

The role of the thymus in the development and pathogenesis of acetylcholine antibody myasthenia gravis is well documented. The ability of thymectomy to alter the course of the disease has been debated for many years, and now finally has been proven to clearly improve patients with the publication of the prospective randomized trial of thymectomy versus medical therapy alone. The trial definitively proves the validity of thymectomy for non-thymomatous myasthenia gravis, the maximal thymectomy surgical resection tested in the trial was critically chosen to address the anatomic presence of thymic tissue outside of the confines of the defined lobes of the thymus in the neck and mediastinum. Given the clear results of the trail, presently maximal thymectomy is the only proven valid resection in the treatment of myasthenia gravis.

Role of VATS in thymectomy for non-thymomatous myasthenia gravis

BackgroundThere are different surgical techniques used for thymectomy. Each technique has its own advantages and disadvantages. However, using a less invasive approach would provide a better outcome. MethodsFrom June 2015 to February 2017, a prospective study included a total number of 50 patients of non-thymomatous myasthenia gravis (MG) who were randomly divided into two groups: group A (25 patients who underwent VATS thymectomy), and group B (25 patients who underwent thymectomy via ministernotomy). Efficacy and outcome of both procedures were compared. Patients were followed-up for at least one year postoperatively. ResultsBoth procedures were safe and effective in the management of MG. There was no significant difference between both groups regarding preoperative data. In VATS group, there were significant decreased operative times (p value = 0.00), significant decreased blood loss (p value = 0.039), significant decreased postoperative respiratory and cardiac complications (p value = 0.025 and 0.018 respectively) and significant shorter length of ICU and hospital stays (p value = 0.039 and 0.007 respectively) when compared to ministernotomy group. There was no statistically significant difference between both groups regarding complete stable remissions and clinical improvement. No mortality was recorded in both groups. ConclusionsThoracoscopic thymectomy should be the technique of choice in the management of MG. It has better intraoperative and short-term results than that of thymectomy via ministernotomy. However, longer periods of follow-up is needed to evaluate long-term results properly.

A crucial first randomized controlled trial of thymectomy in non-thymomatous myasthenia gravis.

The much awaited results of a randomized trial of thymectomy in myasthenia gravis (MG) were published in the August 11, 2016 edition of New England Journal of Medicine by Wolfe et al . on behalf of the “Thymectomy trial in non-thymomatous myasthenia gravis patients receiving prednisone therapy” (MGTX) study group (1). This landmark publication stands as the only controlled randomized thymectomy trial, hoping to end a 75-year-old controversy.

Myasthenia gravis: a clinical-immunological update.

Myasthenia gravis (MG) is the archetypic disorder of both the neuromuscular junction and autoantibody-mediated disease. In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to muscle-specific tyrosine kinase while the remainder of seronegative MG is being explained through cell-based assays using a receptor-clustering technique and, to a lesser extent, proposed new antigenic targets. The incidence and prevalence of MG are increasing, particularly in the elderly. New treatments are being developed, and results from the randomised controlled trial of thymectomy in non-thymomatous MG, due for release in early 2016, will be of particular clinical value. To help navigate an evidence base of varying quality, practising clinicians may consult new MG guidelines in the fields of pregnancy, ocular and generalised MG (GMG). This review focuses on updates in epidemiology, immunology, therapeutic and clinical aspects of GMG in adults.

Thymectomy for non-thymomatous myasthenia gravis: a propensity score matched study.

BackgroundThe efficacy of thymectomy in patients with non-thymomatous Myasthenia Gravis (MG) is still unclear. Main limitations have been variable outcome definitions, lack of a control group and adjustment for confounding.ObjectiveTo study the efficacy of thymectomy in achieving remission or minimal manifestation (R/MM) status in patients with non-thymomatous MG.MethodsPatients with generalized MG and minimum follow-up of 6 months were included. Demographic data and treatments were recorded, as well as the MGFA post-intervention status at the last visit. Propensity scores were used to create a matched cohort of treated and untreated patients. Standard and Bayesian Cox models were used to study treatment effects.ResultsOf 395 patients included, 183(46%) had a thymectomy. Thymectomy patients were younger (p < 0.001), with more females (p < 0.001) and more patients in MGFA classes 4–5 at diagnosis (p = 0.01). A matched cohort of thymectomized patients and controls (n = 98) was created. The hazard ratio (HR) for the matched cohort was 1.9 (CI:1.6-2.3), favoring thymectomy. The predicted R/MM rate was 21% in treated and 6% in controls at 5 years (Absolute difference:15%). A Bayesian Cox model for the matched cohort had an estimated probability of thymectomy efficacy (HR > 1) of 96% using a non-informative prior, and 79% using a skeptical prior.DiscussionWhen controlling for potential confounders, thymectomized patients had a higher probability of achieving R/MM status through time compared to controls. This study provides class III evidence of the efficacy of thymectomy in non-thymomatous myasthenia gravis.

Is thymectomy in non-thymomatous myasthenia gravis of any benefit?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was if thymectomy in non-thymomatous myasthenia gravis was of any benefit? Overall, 137 papers were found using the reported search, of which 16 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The outcome variables were similar in all of the papers, including complete stable remission (CSR), pharmacological remission, age at presentation, gender, duration of symptoms, preoperative classification (Oosterhius, Osserman or myasthenia gravis Foundation of America (MGFA)), thymic pathology, preoperative medications (steroids, immunosuppressants), mortality and morbidity. We conclude that evidence-based reviews have shown that relative rates of thymectomy patients compared with non-thymectomy patients attaining outcome indicate that the former group of patients is more likely to achieve medication-free remission, become asymptomatic and clinically improve (54%, P < 0.01), particularly patients with severe and generalized symptoms (P = 0.007). Patients with generalized myasthenia gravis showed 11% stronger association with favourable outcomes after thymectomy. Some studies show early remission rates (RRs), as early as 6 months post-thymectomy, of 44%. Overall, the reported remission rate for non-thymomatous myasthenia gravis is between 38 and 72% up to 10 years of follow-up. Among these patients, those with thymic hyperplasia show the best complete stable remission rates (42%, P < 0.04) in the majority of studies. Age showed variability across the studies and the cut-off was also different among them. Overall age < 45 years showed a higher probability of achieving complete stable remission during follow-up (81% benefit rate (BR), P < 0.02). Pharmacological improvement is reported between 6 and 42%. However, the certainty of these benefits has not been established due to factors such as the confounding differences between myasthenia gravis patients receiving and not receiving thymectomy, the non-randomized nature of class II studies and the lack of Class I evidence to support its use. There is currently a randomized trial ongoing looking at thymectomy by sternotomy vs controls and the results are eagerly awaited.

Thymectomy: role in the treatment of myasthenia gravis

Thymectomy is a frequently used treatment for myasthenia gravis (MG) and is virtually always indicated in MG patients who have a thymoma. However, the evidence for thymectomy in non-thymomatous MG remains less certain-no randomised controlled trials have been published to date, although one is currently underway. We reviewed the management and clinical outcome of patients with MG who underwent thymectomy over a 12 year period. Eighty-nine patients who underwent transsternal thymectomy were identified. A thymoma was identified on histology in 24 %, whereas 48, 9 and 19 % had hyperplastic, atrophic and normal thymic histology, respectively. One patient developed post operative myasthenic crisis but generally the procedure was well tolerated. Outcome was favourable for the majority of patients, with 34 % achieving complete stable remission (CSR) and an additional 33 % achieving pharmacological remission. Moreover, steroid requirements fell progressively during follow-up. Patients with a hyperplastic gland had a significantly greater chance of achieving CSR compared to other histological subtypes and the incidence of CSR increased with a longer duration of follow-up. Thymectomy for MG is generally safe and well tolerated and is associated with a sustained improvement of symptoms in the majority of patients.

Long-Term Follow-Up After Robotic Thymectomy for Nonthymomatous Myasthenia Gravis

Thymectomy is recognized as a significant component in the treatment of myasthenia gravis. However, controversy exists as to the optimal surgical approach. This investigation summarizes our experience performing extended thymectomy using a robotic technique in a large group of patients with significant follow-up. Data collection for patients undergoing robotic thymectomy for nonthymomatous myasthenia gravis over a 6-year period was prospectively performed. Patients were assessed using the Myasthenia Gravis Foundation of America's quantitative disease severity score and the post intervention status classification. During the study period, 75 patients underwent thymectomy by this method. Mean preoperative myasthenia gravis severity score was 2.7. Mean operative time was 113±46 minutes. Extubation in the operating room occurred in 73 (98%) patients. Mean intensive care stay and total hospital length of stay were 0.9 and 2.2 days respectively. Mean interval between surgery and return to work (or prethymectomy activities of daily living) was 15±6 days. Significant improvement of myasthenia gravis symptoms occurred in 65 (87%) patients with a mean follow-up of 45±14 months. Robotic-assisted thymectomy is a safe and effective technique for patients with symptomatic myasthenia gravis. It allowed an extended thymectomy to be performed without the associated length of stay or recovery period of a transsternal approach while producing comparable rates of symptom improvement.

VATS Thymectomy for Nonthymomatous Myasthenia Gravis Standardized Outcome Assessment Using the Myasthenia Gravis Foundation of America Clinical Classification

: Video-assisted thoracoscopic (VATS) thymectomy has been practiced in Australia for nearly two decades. Our aim was to assess the complete stable remission and asymptomatic disease rates after VATS thymectomy in nonthymomatous myasthenia gravis. There remains doubt that minimally invasive techniques achieve equal remission rates to open maximal operations. Therefore, we report our outcomes using the Myasthenia Gravis Foundation of America (MGFA) Clinical Classification and Kaplan-Meier analysis and compare the results to the literature. : A retrospective analysis of 78 consecutive patients undergoing right VATS thymectomy between April 1994 and March 2007 at two Thoracic Surgery Units in Melbourne, Australia, was undertaken. Patients with thymoma were excluded. Therefore, 57 patients were followed-up for a minimum of 12 months to apply the MGFA Clinical Classification. VATS thymectomy was performed by a three-port right side technique. : The complete stable remission rate was 15% at 3 years and 28% at 5 years. The asymptomatic disease rate was 59% at 5 years. Median follow-up was 32 months. No prognostic factors for remission were identified. The overall morbidity rate was 14% (8/57). : Right VATS thymectomy achieves comparable remission and asymptomatic disease rates to other minimally invasive and open techniques when compared with studies using either MGFA or older criteria.

Thymectomy for non-thymomatous myasthenia gravis: a comparison of surgical methods and analysis of prognostic factors

While thymectomy is an accepted treatment for myasthenia gravis (MG), video-assisted thoracoscopic surgery (VATS) thymectomy has recently become a popular surgical treatment, especially for non-thymomatous MG (NTMG). This study aims to compare the results of VATS thymectomy and trans-sternal thymectomy, and identify prognostic factors in NTMG patients after thymectomy. A 10-year retrospective review (January 1995 to December 2004) of 60 consecutive thymectomies (22 trans-sternal thymectomies and 38 VATS thymectomies) of NTMG patients performed in a university teaching hospital was undertaken. There were 43 female patients and 17 male patients with a median MG-onset age of 25 years (range: 5-78 years). Median follow-up time was 44 months. VATS thymectomy patients had a shorter hospital stay than the trans-sternal thymectomy patients (5.6 days vs 8.1 days, p=0.008). There was no other statistically significant difference between the two operative methods in NTMG patients, including intensive care unit (ICU) stay, ventilator support time, operative time, postoperative status, complete stable remission (CSR) rate, morbidity and mortality. Three prognostic factors associated with better remission rate were hyperthyroidism (p=0.003), age <40 years (p=0.022) and the presence of thymic hyperplasia (p=0.041). Other factors, including gender, disease duration, preoperative MG severity, acetylcholine receptor antibody, perioperative therapy and operative methods (32% vs 36%, p=0.91, 95% confidence interval (CI)=0.27-3.21) were not statistically relevant to better remission rate. VATS thymectomy is more advantageous for NTMG patients because of shorter hospital stay, less tissue injury, better cosmetic result and equivalent CSR rate. NTMG patients aged <40 years with hyperthyroidism and a histologic diagnosis of lymphofollicular hyperplasia have better chances of remission after thymectomy.

Long-term outcome of thoracoscopic extended thymectomy for nonthymomatous myasthenia gravis☆☆☆

Thoracoscopic thymectomy has shown promise in the integrated management of myasthenia gravis (MG) although there is still scant data on long-term results. The aim of this study was to analyze long-term (>5 years) results of thoracoscopic extended thymectomy in nonthymomatous MG. We retrospectively reviewed 32 patients operated on between 1995 and 2003. MG foundation of America clinical classification (MGFA), symptoms' duration, preoperative crisis, anticholinesterase-drugs dosage, steroid use, and acetylcholine receptor antibodies were evaluated in all patients with annual follow-up. Anti-MuSK antibody titer was also assessed at the last follow-up. There were 21 females and 11 males with a median age of 36 years. Ten patients were seronegative for acetylcholine receptor antibodies. Patients in MGFA class I, II, III and IV were 7 (22%), 15 (44%), 9 (28%), 2 (6%) patients, respectively. Median symptoms duration was 11 months. There was no mortality or major morbidity. Median hospital stay was 4.0 days. Ectopic thymic tissue was found in 18 (56%) patients. Median follow-up was 119 months (range 60-156 months). There was no residual thoracic pain. Estimated 10-year remission rate was 50%. At 72 months, 27 (84.3%) patients were improved or in complete remission. At the univariate analysis, shorter duration of symptoms (<12 months) and absence of oropharyngeal involvement were both predictors of response to thymectomy (p<0.02) whereas positivity for anti-MuSK antibody was a predictor of non-response (p=0.0007). Thoracoscopic extended thymectomy yields satisfactory long-term results in patients with nonthymomatous myasthenia gravis although anti-MuSK positivity correlated with poor response to operation.