Video-assisted thoracoscopic extended thymectomy and extended transsternal thymectomy (T-3b) in non-thymomatous myasthenia gravis patients: remission after 6 years of follow-up

Are the minimally invasive techniques the new gold standard in thymus surgery for myasthenia gravis? Experience of a reference single-site in VATS thymectomy

The thymus is the primary lymphoid organ responsible for the maturation and proliferation of T lymphocytes. During the first years of our lives, the activation and inactivation of T lymphocytes occur within the thymus, facilitating the correct maturation of central immunity. Alterations in the positive and negative selection of T lymphocytes have been studied as the possible origins of autoimmune diseases, with Myasthenia Gravis (MG) being the most representative example. Structural alterations in the thymus appear to be involved in the initial autoimmune response observed in MG, leading to the consideration of thymectomy as part of the treatment for the disease. However, the role of thymectomy in MG has been a subject of controversy for many years. Several publications raised doubts about the lack of evidence justifying thymectomy's role in MG until 2016 when a randomized study comparing thymectomy via sternotomy plus prednisone versus prednisone alone was published in the New England Journal of Medicine (NEJM). The results clearly favored the group of patients who underwent surgery, showing improvements in symptoms, reduced corticosteroid requirements, and fewer recurrences over 3 years of follow-up. In recent years, the emergence of less invasive surgical techniques has made video-assisted or robotic-assisted thoracoscopic (VATS/RATS) thymectomy more common, replacing the traditional sternotomy approach. Despite the increasing use of VATS, it has not been validated as a technique with lower morbidity compared to sternotomy in the treatment of MG. The results of the 2016 trial highlighted the benefits of thymectomy, but all the patients underwent surgery via sternotomy. Our hypothesis is that VATS thymectomy is a technique with lower morbidity, reduced postoperative pain, and shorter postoperative hospital stays than sternotomy. Additionally, VATS offers better clinical improvement in patients with MG. The primary objective of this study is to validate the VATS technique as the preferred approach for thymectomy. Furthermore, we aim to analyze the impact of VATS thymectomy on symptoms and corticosteroid dosage in patients with MG, identifying factors that may predict a better response to surgery.

Unilateral Thoracoscopic Thymectomy for Thymoma: Does Side Matter? A Single Institutional Experience

BACKGROUND

Thoracoscopic thymectomy is increasingly performed for the treatment of early stage thymoma. It is characterized by shorter postoperative hospital stay, decreased intraoperative blood loss, and fewer complications compared with transsternal thymectomy. Unilateral video-assisted thoracic surgery (VATS) thymectomy can be easily performed from either side of the thorax, because thymus is located in the middle of mediastinum. However, the side that provides better outcomes remains controversial. The purpose of this study was to compare the efficacy of right and left approaches in performing unilateral thoracoscopic thymectomy for thymoma.

METHODS

Consecutive patients affected by thymoma who underwent VATS thymectomy on either side between February 2001 and March 2020 were enrolled in the study. Clinicopathologic, surgical, and oncological outcomes were retrospectively analyzed and compared among the two surgical approaches.

RESULTS

Unilateral VATS approaches were performed on 29 patients: 12 (41%) on the left side and 17 (59%) on the right side. The mean age was 63.1 ± 11.3 years and the female/male ratio was 1.73:1. The mean operative time and the hospital stay for the left-side VATS and right-side VATS groups were, respectively, 168 ± 49.5 versus 171 ± 47.9 minutes (p = 0.9) and 3 ± 1.03 days versus 3.65 ± 1.93 days (p = 0.7). Postoperative complications occurred in one patient (3%) for left-side VATS group and one patient (3%) for right-side VATS. The 5-year disease-free survival was comparable between two groups (p = 0.74).

CONCLUSION

Unilateral VATS thymectomy in patients with thymoma can be safely and effectively performed by experienced surgeons in either side of the thorax with equivalent oncological outcomes.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

26 studies with 3588 patients were included in the analysis. At 1, 3 and 5 years, there was no statistical difference noted in CSR between open versus MIS thymectomy. However, CSR was improved at 1 year 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.

CONCLUSION

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.

Poor responses and adverse outcomes of myasthenia gravis after thymectomy: Predicting factors and immunological implications

Myasthenia gravis (MG) has been recognized as a series of heterogeneous but treatable autoimmune conditions. As one of the indispensable therapies, thymectomy can achieve favorable prognosis especially in early-onset generalized MG patients with seropositive acetylcholine receptor antibody. However, poor outcomes, including worsening or relapse of MG, postoperative myasthenic crisis and even post-thymectomy MG, are also observed in certain scenarios. The responses to thymectomy may be associated with the general characteristics of patients, disease conditions of MG, autoantibody profiles, native or ectopic thymic pathologies, surgical-related factors, pharmacotherapy and other adjuvant modalities, and the presence of comorbidities and complications. However, in addition to these variations among individuals, pathological remnants and the abnormal immunological milieu and responses potentially represent major mechanisms that underlie the detrimental neurological outcomes after thymectomy. We underscore these plausible risk factors and discuss the immunological implications therein, which may be conducive to better managing the indications for thymectomy, to avoiding modifiable risk factors of poor responses and adverse outcomes, and to developing post-thymectomy preventive and therapeutic strategies for MG.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Minimally invasive thymectomy for myasthenia gravis: a 7-year retrospective study

BACKGROUND

Thymectomy has been identified as an effective strategy for patients with myasthenia gravis (MG) and thymic masses. However, the best surgical approach remains a matter of debate. The aim of the present study was to compare the surgical and neurological outcomes of video-assisted thoracoscopic thymectomy with a modified subxiphoid and bilateral approach in patients with MG and thymic masses.

METHODS

From August 2013 to April 2018, 68 patients who were diagnosed with MG and thymic masses and underwent video-assisted thoracoscopic thymectomy with a modified subxiphoid (44 patients) or bilateral (24 patients) approach were included in this retrospective study. The surgical and neurological results were analyzed with propensity score matching.

RESULTS

After propensity score matching, the modified subxiphoid approach in video-assisted thoracoscopic thymectomy resulted in an obviously shorter operative time (P=0.00), drainage duration (P=0.00), less intraoperative blood loss (P=0.00), and shorter postoperative hospital stay (P=0.01). In terms of neurological outcomes, no significant difference was observed in the improvement in MG, with 2-year complete stable remission rates of 21.1% and 26.3% (P=0.68) and 2-year pharmacological remission rates of 31.6% and 26.3% (P=0.60) for the bilateral and subxiphoid approaches, respectively. Additionally, the approaches resulted in similar effects on the magnitudes of decrease in the prednisolone and pyridostigmine doses after 2 years, with average pyridostigmine dose reductions of 72.2% and 71.1% (P=0.78) and average prednisolone reductions of 76.8% and 71.7% (P=0.96) for the bilateral and subxiphoid approaches, respectively.

CONCLUSIONS

The modified subxiphoid approach was found to be superior to the bilateral approach in video-assisted thoracic surgery thymectomy in terms of the surgical outcomes and yielded similar neurological outcomes. Therefore, the modified subxiphoid approach is recommended as an alternative to the bilateral approach in the treatment of patients with MG and thymic masses.

Determinants of Suboptimal Outcome Following Thymectomy in Myasthenia Gravis

Background

Response to thymectomy in myasthenia gravis (MG) is influenced by various patient-, disease-, and therapy-related factors.

Methods

Retrospective analysis of 128 patients with MG who underwent maximal thymectomy over 15 years was done to identify the determinants of suboptimal clinical outcome.

Results

Among the 128 patients, 62 (48.4%) were females with a mean age of 38.97 (12.29) years. Thymomatous MG occurred in 66 (51.6%). Overall improvement from preoperative status was noted in 88 (68.8%) patients after mean follow-up of 51.68 (33.21) months. The presence of thymoma was the major predictor of suboptimal clinical outcome (P = 0.001), whereas age, gender, preoperative disease severity, and seropositive status did not attain significance. Patients with better outcome had received higher steroid dose preoperatively (P = 0.035).

Conclusions

Suboptimal response after thymectomy occurred in one-third of MG patients, more commonly with thymomatous MG. Relationship of preoperative steroid therapy to remission merits evaluation.

Effects of thymectomy on late-onset non-thymomatous myasthenia gravis: systematic review and meta-analysis

BACKGROUND

The effects of thymectomy on late-onset non-thymomatous myasthenia gravis (NTMG) remain controversial. The objective of this study was to conduct a systematic review in order to answer two questions pertinent to late-onset NTMG: (1) do patients with late-onset NTMG experience the same effects from thymectomy as their early-onset counterparts? (2) Compared with conservative treatment, does thymectomy have any benefits for late-onset NTMG patients?

METHODS

We searched the PubMed, EMBASE, and Cochrane Library databases for studies published from January 1, 1950 to March 10, 2021. Outcomes were measured via clinical stable remission/pharmacological remission (CSR/PR) and improvement rates. We used Stata software to analyze the data.

RESULTS

We ultimately included a total of 12 observational articles representing the best evidence answering the questions of our study objective. Of these, nine studies, which included 896 patients overall (766 early-onset and 230 late-onset), compared postoperative outcomes between early- and late-onset NTMG. The remaining three articles, which included 216 patients (75 in the thymectomy group and 141 in the conservative-treatment group), compared thymectomy with conservative treatment for late-onset NTMG. The early- versus late-onset NTMG studies demonstrated that patients in the former category were 1.95× likelier than their late-onset counterparts to achieve clinical remission (odds ratio [OR] 1.95; 95% confidence interval [CI] 1.39-2.73; I2 = 0%). No difference was seen in improvement or remission + improvement rates between these two groups. When comparing thymectomy with conservative treatments in late-onset NTMG patients, neither did we observe any difference in CSR/PR.

CONCLUSION

We found that late-onset NTMG patients had a lower chance of achieving CSR after thymectomy than early-onset patients. Thymectomy in late-onset NTMG also yielded no benefit to CSR or PR compared with conservative treatments. In late-onset NTMG patients, thymectomy should therefore be performed with caution, and the appropriate cutoff between early- and late-onset MG should be further explored in order to tailor and execute the proper therapeutic strategies.

Unraveling the role of ectopic thymic tissue in patients undergoing thymectomy for myasthenia gravis

Extended thymectomy has been considered the goal of surgery for myasthenia gravis (MG) mainly due to the existence of ectopic thymic tissue. Recently, ectopic thymic tissue has attracted increasing attention in patients with MG following thymectomy. However, the specific role of ectopic thymic tissue in patients with MG is still under debate. A systematic search of the literature was performed on PubMed and Medline according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISM) statement. Studies evaluating the rate of ectopic thymic tissue in patients with MG with or without thymoma were included. Extraction was performed for all eligible studies and the rate of ectopic thymic tissue at common locations was calculated. Eighteen out of fifty-nine studies were eligible for inclusion, of which ten studies reported the common locations of ectopic thymic tissue in mediastinal fat. Of these ten studies, the presence of ectopic thymic tissue was investigated in different anatomical locations in 882 patients, of whom, 509 patients (58%) have at least one positive location with the most common ones being anterior mediastinal fat, pericardiophrenic angles, aortopulmonary window, cervical region (pretracheal fat) and lateral to phrenic nerves. On the other hand, nine studies analyzed the influence of the presence of ectopic thymic tissue on the clinical outcomes of MG patients. Of these, six found that the presence of ectopic thymic tissue in MG patients is a significant predictor of poor outcome after thymectomy, however, the other three did not find a significance. Altogether, ectopic thymic tissue is likely to present in more than a half of patients undergoing thymectomy for MG. Besides, MG patients who have ectopic thymic tissue after thymectomy do not seem to have as good outcome as those who have not.

Italian recommendations for the diagnosis and treatment of myasthenia gravis

Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.

Effect of thymectomy in elderly patients with non-thymomatous generalized myasthenia gravis

Whether thymectomy is beneficial in elderly patients with myasthenia gravis (MG) is unclear. Thus, we assessed whether conducting thymectomy in MG patients aged ≥ 50 years is beneficial. This retrospective cohort study included patients with MG between 1990 and 2018. Thymectomy and control cohorts were selected from among the population of MG patients with an age at onset of ≥ 45 years and elevated concentrations of acetylcholine-receptor antibodies. Patients with evidence of thymic malignancy were excluded. Of these patients, those who underwent thymectomy at the age of ≥ 50 years were designated as the thymectomy group and those who received only medical treatment were designated as the medical treatment group. We compared the Myasthenia Gravis Foundation of America post-intervention status between the thymectomy and medical treatment groups. Landmark analysis was conducted with the landmark set at 24 months. A total of 34 and 105 patients were classified into the thymectomy and medical treatment groups, respectively. Before landmark analysis, the thymectomy group had a higher cumulative incidence of pharmacologic remission (p = 0.009) and complete stable remission (p = 0.022) than the medical treatment group. After landmark analysis, the thymectomy group had a 2.22-fold (95% confidence interval 1.01-4.80) increased chance of achieving pharmacologic remission compared to the medical treatment group after adjustment for age, sex, and disease severity. No significant difference was observed in the rate of relapse after pharmacological remission between the thymectomy (16.7%) and medical treatment groups (21.4%). In conclusion, thymectomy may have a beneficial effect in elderly patients with non-thymomatous generalized MG.

Predictive value of the thymofatty specimen weight index in outcomes of extended thymectomy due to non-thymomatous myasthenia gravis

OBJECTIVES

To evaluate the predictive value of the intraoperative thymofatty specimen weight (TFSW) index on predicting the prognosis of extended thymectomy (ET) for non-thymomatous myasthenia gravis.

METHODS

This is a prospective non-interventional study in which patients who underwent ET between January 2012 and June 2015 were enrolled. Resected thymus and surrounding adipose tissues were weighed using an electronic scale intraoperatively and adjusted to the body surface area (BSA) to calculate the TFSW index. The primary end point was defined as complete stable remission (CSR) according to the Myasthenia Gravis Foundation of America (MGFA) guidelines.

RESULTS

One hundred and eighteen patients who completed postoperative follow-up were included in this study. After a mean follow-up period of 44 months, 68 (57.6%) patients reached clinical CSR. The MGFA class, histopathology and TFSW index were associated with a postoperative CSR in univariate analysis. When the Cox hazard multiple regression model was used, the TFSW index was found to be an independent predictor for CSR (hazard ratio 2.056; 95% confidence interval 1.182-3.576). Based on ROC analysis, an optimal TFSW index cut-off value (35.9 g/m2) with the highest sensitivity and specificity was determined.

CONCLUSIONS

The TFSW index is an important independent predictor for mid-term CSR after ET in non-thymomatous myasthenia gravis patients. During the ET surgery, every effort should be made to take a tissue specimen with a TFSW index more than 35.9 g/m2.

Myasthenia Gravis and Thymoma Surgery: A Clinical Update for the Cardiothoracic Anesthesiologist

Myasthenia gravis (MG) is a rare neuromuscular disorder characterized by skeletal muscle weakness. Patients with MG who have thymoma and thymic hyperplasia have indications for thymectomy. The perioperative care of patients with MG scheduled for thymus resection should be focused on optimizing their neuromuscular function, identifying factors related to postoperative mechanical ventilation, and avoiding of triggers associated with myasthenic or cholinergic crisis. Minimally invasive surgical techniques, use of regional analgesia, and avoidance or judicious administration of neuromuscular blocking drugs (NMBs) is recommended during the perioperative period. If NMBs are used, sugammadex appears to be the drug of choice to restore adequately the neuromuscular transmission. In patients with postoperative myasthenic crisis, plasma exchange or intravenous immune globulin and mechanical support is recommended.

Toll-like receptors 7 and 9 in myasthenia gravis thymus: amplifiers of autoimmunity?

Pathogen infections and dysregulated Toll-like receptor (TLR)-mediated innate immune responses are suspected to play key roles in autoimmunity. Among TLRs, TLR7 and TLR9 have been implicated in several autoimmune conditions, mainly because of their ability to promote abnormal B cell activation and survival. Recently, we provided evidence of Epstein-Barr virus (EBV) persistence and reactivation in the thymus of myasthenia gravis (MG) patients, suggesting an involvement of EBV in the intrathymic pathogenesis of the disease. Considerable data highlight the existence of pathogenic crosstalk among EBV, TLR7, and TLR9: EBV elicits TLR7/9 signaling, which in turn can enhance B cell dysfunction and autoimmunity. In this article, after a brief summary of data demonstrating TLR activation in MG thymus, we provide an overview on the contribution of TLR7 and TLR9 to autoimmune diseases and discuss our recent findings indicating a pivotal role for these two receptors, along with EBV, in driving, perpetuating, and/or amplifying intrathymic B cell dysregulation and autoimmune responses in MG. Development of therapeutic approaches targeting TLR7 and TLR9 signaling could be a novel strategy for treating the chronic inflammatory autoimmune process in myasthenia gravis.

Epstein-Barr virus in tumor-infiltrating B cells of myasthenia gravis thymoma: an innocent bystander or an autoimmunity mediator?

The thymus plays a key role in myasthenia gravis (MG), a B cell-mediated autoimmune disorder affecting neuromuscular junction. Most MG patients have thymic abnormalities, including hyperplasia and thymoma, a neoplasm of thymic epithelial cells. Epstein-Barr virus (EBV) is associated with autoimmune diseases and tumors. Recently, we showed EBV persistence and reactivation in hyperplastic MG thymuses, suggesting that EBV might contribute to intra-thymic B cell dysregulation in MG patients. Here, we investigated EBV involvement in thymoma-associated MG, by searching for EBV markers in MG (n=26) and non-MG (n=14) thymomas. EBV DNA and EBV-encoded small nuclear RNA (EBER) 1 transcript were detected in 14/26 (53.8%) and 22/26 (84.6%) MG thymomas, and only in 3 of 14 (21.4%) non-MG thymomas. Latent EBNA2 and late gp350/220 lytic transcripts were undetectable in all, but one, thymomas, and early lytic BZLF1 transcript was absent in all samples, suggesting that early infection events and EBV reactivation were very rare in thymomas. EBER1 and 2-positive cells were detected in MG, but not in non-MG, thymomas, as well as cells expressing EBV latency proteins (EBNA1, LMP1, LMP2A), that were mainly of B cell phenotype, indicating EBV association with MG rather than with thymoma. Toll-like receptor (TLR) 3 transcriptional levels were higher in MG than non-MG thymomas and positively correlated with EBER1 levels, suggesting a role for EBERs in TLR3 activation. Our findings show that EBV is commonly present in thymoma-infiltrating B cells of myasthenic patients, indicating a contribution of EBV to B cell-mediated autoreactivity in MG associated with thymic tumor.

The results of video-assisted thoracoscopic thymectomies in Saint Petersburg, Russia: 20-year of experience

BACKGROUND

During the period from 1996 to 2016, we have performed 281 thymectomies in patients with various diseases of the thymus. In 179 patients, thymic pathology was associated with autoimmune myasthenia gravis (MG), and, in 108 patients, thymoma was diagnosed.

METHODS

The majority of surgeries [254] were performed using video thoracoscopy, 79 of them with an additional cervical approach. The long-term results of video thoracoscopic thymectomies in myasthenic patients were followed up for 1 to 15.5 years.

RESULTS

In 26% of the patients, a complete and stable remission was achieved, in 47%-clinical manifestation improved. Local recurrence of thymoma developed in one patient (0.9%).

CONCLUSIONS

Comparison of postoperative complications and long-term results demonstrated that extended video-assisted thoracoscopic thymectomy (VATS-TE) is a radical, efficient, safe, technically feasible and a well-tolerated surgery. It improves the course of MG as a part of multimodality treatment more efficiently than a conservative therapy alone. The course of MG after VATS-TE shows that the cumulative incidence of remissions/improvements reaches its maximum by the 3rd year after the surgery. VATS-TE is radical and safe for removal of noninvasive thymomas up to 8 cm in size. Additional neck incision (VATS-TE + cervical approach) does not provide further advantages, but rather may be a cause of specific postoperative complications.

A propensity score analysis for comparison of T-3b and VATET in myasthenia gravis

Objective:

We performed propensity score (PS) models to compare the outcome of patients with myasthenia gravis (MG) submitted to 2 different surgical approaches: extended transsternal (T-3b) or thoracoscopic extended thymectomy (VATET).

Methods:

Patients' clinical data were retrieved from the MG database of the C. Besta Neurologic Institute Foundation. In the PS analysis, a matching ratio of 1:1 of the main clinical variables was obtained for the 2 groups of patients and treatment effect was estimated by comparing their outcome.

Results:

A total of 210 patients met the inclusion criteria, by having a complete set of clinical data, and were included in the PS model; a matched dataset of 122 participants (61 per group) showed an adequate balance of all the covariates. Our analysis demonstrated that 68.9% of patients who had thymectomy by the VATET technique reached the pharmacologic remission/remission status at 2 years from thymectomy compared to 34.4% of those operated on by the T-3b technique (p < 0.001), had a lower INCB-MG score (p < 0.001), and had less muscle fatigability (p = 0.004). Similar results were found considering only nonthymomatous patients with MG. Results were also confirmed by paired statistical tests.

Conclusions:

Our PS matching analysis showed that VATET is a reliable and effective surgical approach alternative to T-3b in patients with MG who are candidates for thymectomy.

Classification of evidence:

This study provides Class IV evidence that for patients with MG, VATET is more effective than T-3b thymectomy.

Thymic Germinal Centers and Corticosteroids in Myasthenia Gravis: an Immunopathological Study in 1035 Cases and a Critical Review

The most common form of Myasthenia gravis (MG) is due to anti-acetylcholine receptor (AChR) antibodies and is frequently associated with thymic pathology. In this review, we discuss the immunopathological characteristics and molecular mechanisms of thymic follicular hyperplasia, the effects of corticosteroids on this thymic pathology, and the role of thymic epithelial cells (TEC), a key player in the inflammatory thymic mechanisms. This review is based not only on the literature data but also on thymic transcriptome results and analyses of pathological and immunological correlations in a vast cohort of 1035 MG patients without thymoma. We show that among patients presenting a thymic hyperplasia with germinal centers (GC), 80 % are females, indicating that thymic follicular hyperplasia is mainly a disease of women. The presence of anti-AChR antibodies is correlated with the degree of follicular hyperplasia, suggesting that the thymus is a source of anti-AChR antibodies. The degree of hyperplasia is not dependent upon the time from the onset, implying that either the antigen is chronically expressed and/or that the mechanisms of the resolution of the GC are not efficiently controlled. Glucocorticoids, a conventional therapy in MG, induce a significant reduction in the GC number, together with changes in the expression of chemokines and angiogenesis. These changes are likely related to the acetylation molecular process, overrepresented in corticosteroid-treated patients, and essential for gene regulation. Altogether, based on the pathological and molecular thymic abnormalities found in MG patients, this review provides some explanations for the benefit of thymectomy in early-onset MG patients.

Sternotomy versus video-assisted thoracoscopic surgery for thymectomy of myasthenia gravis patients: A meta-analysis

INTRODUCTION

The purpose of this study was to compare thymectomy by video-assisted thoracoscopic surgery (VATS) and trans-sternal thymectomy (TS) for myasthenia gravis patients.

METHODS

A meta-analysis was conducted to compare thoracoscopic surgery and sternotomy for myasthenia gravis patients with regard to long-term effect and short-term safety.

RESULTS

A total of 23 trials were included in our research. No significant differences were detected with regard to myasthenic crisis, wound infection, and muscle weakness improvement. VATS led to less blood loss than TS (standardized mean difference, -1.233; 95% confidence interval, -1.425--1.041; P < 0.001), less risk of pulmonary infection (relative risk, 1.035; 95% confidence interval, 1.001-1.070; P = 0.043), and a shorter hospital stay. TS had a shorter operative time than VATS (standardized mean difference, 0.239; 95% confidence interval, 0.113-0.365; P < 0.001). VATS and TS achieved similar mean specimen weights and complete stable remission rates.

CONCLUSION

Based on the results of this meta-analysis of retrospective cohort studies, VATS increases surgical safety and achieves an equal surgical efficacy to TS, but TS has a shorter operative time.

Comparative clinical outcomes after thymectomy for myasthenia gravis: Thoracoscopic versus trans-sternal approach

BACKGROUND

Thymectomy is an effective treatment option for long-term remission of myasthenia gravis. The superiority of the trans-sternal and thoracoscopic surgical approaches is still being debated. The aims of this study are to compare postoperative outcomes and neurologic outcomes between the two approaches and to identify prognostic factors for complete stable remission (CSR).

METHODS

Myasthenia gravis patients who underwent thymectomy with trans-sternal or thoracoscopic approach in MahaRaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand between January1, 2006 and December 31, 2013 were retrospectively reviewed. The endpoints were postoperative outcomes and cumulative incidence function for CSR. The analysis was performed using multilevel model, Cox's proportional hazard model, and propensity score.

RESULTS

Ninety-eight patients were enrolled in this study: 53 in the thoracoscopic group and 45 in the trans-sternal group. There were no significant differences between groups in composite postoperative complications, surgical time, ventilator support days, and length of intensive care unit stay. Intraoperative blood loss and length of hospital stay were significant less in the thoracoscopic group. The CSR and median time to remission were not significantly different between the two approaches. Prognostic factors for CSR were nonthymoma (hazard ratio: 3.5, 95% confidence interval: 1.01-12.22) and presence of pharmacological remission (hazard ratio: 24.3, 95% confidence interval: 3.27-180.41).

CONCLUSION

Thoracoscopic thymectomy is safe and provides good neurologic outcomes in comparison to the trans-sternal approach. Two predictive factors should be considered for CSR. Further prospective studies with a larger sample size and longer follow-up period are warranted to confirm these results.

Report on First International Workshop on Robotic Surgery in Thoracic Oncology

A workshop of experts from France, Germany, Italy, and the United States took place at Humanitas Research Hospital Milan, Italy, on February 10 and 11, 2016, to examine techniques for and applications of robotic surgery to thoracic oncology. The main topics of presentation and discussion were robotic surgery for lung resection; robot-assisted thymectomy; minimally invasive surgery for esophageal cancer; new developments in computer-assisted surgery and medical applications of robots; the challenge of costs; and future clinical research in robotic thoracic surgery. The following article summarizes the main contributions to the workshop. The Workshop consensus was that since video-assisted thoracoscopic surgery (VATS) is becoming the mainstream approach to resectable lung cancer in North America and Europe, robotic surgery for thoracic oncology is likely to be embraced by an increasing numbers of thoracic surgeons, since it has technical advantages over VATS, including intuitive movements, tremor filtration, more degrees of manipulative freedom, motion scaling, and high-definition stereoscopic vision. These advantages may make robotic surgery more accessible than VATS to trainees and experienced surgeons and also lead to expanded indications. However, the high costs of robotic surgery and absence of tactile feedback remain obstacles to widespread dissemination. A prospective multicentric randomized trial (NCT02804893) to compare robotic and VATS approaches to stages I and II lung cancer will start shortly.

Randomized Trial of Thymectomy in Myasthenia Gravis

BACKGROUND

Thymectomy has been a mainstay in the treatment of myasthenia gravis, but there is no conclusive evidence of its benefit. We conducted a multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone.

METHODS

We compared extended transsternal thymectomy plus alternate-day prednisone with alternate-day prednisone alone. Patients 18 to 65 years of age who had generalized nonthymomatous myasthenia gravis with a disease duration of less than 5 years were included if they had Myasthenia Gravis Foundation of America clinical class II to IV disease (on a scale from I to V, with higher classes indicating more severe disease) and elevated circulating concentrations of acetylcholine-receptor antibody. The primary outcomes were the time-weighted average Quantitative Myasthenia Gravis score (on a scale from 0 to 39, with higher scores indicating more severe disease) over a 3-year period, as assessed by means of blinded rating, and the time-weighted average required dose of prednisone over a 3-year period.

RESULTS

A total of 126 patients underwent randomization between 2006 and 2012 at 36 sites. Patients who underwent thymectomy had a lower time-weighted average Quantitative Myasthenia Gravis score over a 3-year period than those who received prednisone alone (6.15 vs. 8.99, P<0.001); patients in the thymectomy group also had a lower average requirement for alternate-day prednisone (44 mg vs. 60 mg, P<0.001). Fewer patients in the thymectomy group than in the prednisone-only group required immunosuppression with azathioprine (17% vs. 48%, P<0.001) or were hospitalized for exacerbations (9% vs. 37%, P<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (P=0.73), but patients in the thymectomy group had fewer treatment-associated symptoms related to immunosuppressive medications (P<0.001) and lower distress levels related to symptoms (P=0.003).

CONCLUSIONS

Thymectomy improved clinical outcomes over a 3-year period in patients with nonthymomatous myasthenia gravis. (Funded by the National Institute of Neurological Disorders and Stroke and others; MGTX ClinicalTrials.gov number, NCT00294658.).

A novel infection- and inflammation-associated molecular signature in peripheral blood of myasthenia gravis patients

Myasthenia gravis (MG) is a T-cell dependent autoimmune disorder of the neuromuscular junction, characterised by muscle weakness and fatigability. Autoimmunity is thought to initiate in the thymus of acetylcholine receptor (AChR)-positive MG patients; however, the molecular mechanisms linking intra-thymic MG pathogenesis with autoreactivity via the circulation to the muscle target organ are poorly understood. Using whole-transcriptome sequencing, we compared the transcriptional profile of peripheral blood mononuclear cells from AChR-early onset MG (AChR-EOMG) patients with healthy controls: 178 coding transcripts and 229 long non-coding RNAs, including 11 pre-miRNAs, were differentially expressed. Among the 178 coding transcripts, 128 were annotated of which 17% were associated with the 'infectious disease' functional category and 46% with 'inflammatory disease' and 'inflammatory response-associated' categories. Validation of selected transcripts by qPCR indicated that of the infectious disease-related transcripts, ETF1, NFKB2, PLK3, and PPP1R15A were upregulated, whereas CLC and IL4 were downregulated in AChR-EOMG patients; in the 'inflammatory' categories, ABCA1, FUS, and RELB were upregulated, suggesting a contribution of these molecules to immunological dysfunctions in MG. Data selection and validation were also based on predicted microRNA-mRNA interactions. We found that miR-612, miR-3654, and miR-3651 were increased, whereas miR-612-putative AKAp12 and HRH4 targets and the miR-3651-putative CRISP3 target were downregulated in AChR-EOMG, also suggesting altered immunoregulation. Our findings reveal a novel peripheral molecular signature in AChR-EOMG, reflecting a critical involvement of inflammatory- and infectious disease-related immune responses in disease pathogenesis.

Two-year outcome of thymectomy with or without immunosuppressive treatment in nonthymomatous myasthenia gravis and its effect on regulatory T cells

BACKGROUND

Myasthenia gravis (MG) is the autoimmune disorder in which the thymus is considered the pathogenic organ. Thymectomy (TE) is a therapeutic option for MG and often ameliorates clinical symptoms.

METHODS

We evaluated clinical features and outcomes after TE in patients without thymoma and the influence of TE with or without concomitant immunotherapy on the CD4(+)CD25(+) regulatory T cell subpopulation of lymphocytes in peripheral blood in defined followed groups of nonthymomatous MG patients.

RESULTS

A total of 46 patients with generalized MG who underwent transsternal TE were identified. Neurologic outcomes after TE were favorable for the majority of patients mainly from the group treated with corticosteroids or combined immunosuppressive treatment. TEs with immunosuppressive treatment in MG patients were associated with increased percentages of CD4(+)CD25(+) cells (p<0.001). No significant change in the postoperative levels of CD4(+)CD25(+) cells was observed in thymectomized patients who preoperatively only received pyridostigmine. Also their clinical response to TE after 2 years of follow-up was worst of all followed groups.

CONCLUSIONS

The exact mechanism by which TE ameliorates symptoms of MG is yet not clear. These observations indicate that increased percentages of CD4(+)CD25(+) T cells in MG may be related to disease stability and that TE and synergistic effect with concomitant, continuing immunotherapy augmented the proportion of CD4(+)CD25(+) T cells. On the basis of our observations TE alone is not enough to increase the number of circulating CD4(+)CD25(+) regulatory T cells and to establish complete stable remission.

Eight-year follow-up of patients with myasthenia gravis after thymectomy

PURPOSE

To depict the long-term outcome of patients with myasthenia gravis after thymectomy in combination with immunotherapy, and the factors that may potentially affect the outcome.

METHODS

The 306 patients with myasthenia gravis who underwent extended thymectomy from January 1984 to December 2011 at Tongji Hospital were retrospectively evaluated.

RESULTS

The patients consisted of 174 cases with thymoma and 132 cases without thymoma. Pharmaceutical treatment was tailored for each case during follow-up. Nine patients with thymomatous myasthenia gravis died during the perioperative period, and 297 patients were followed for 8.6 years. By their latest visits, 241 patients (81.1%) gained satisfactory efficacy, 24 cases died (8.1%), and 32 cases (10.8%) remained unchanged or deteriorated. Favorable factors for satisfactory efficacy included the presence of ocular myasthenia gravis before operation, no presence of thymoma, and lack of concomitant diseases. It is interesting to mention that, patients with non-thymomatous myasthenia gravis obtained significantly higher rates of complete stable remission and clinical remission than the patients with thymomatous myasthenia gravis.

CONCLUSIONS

Extended thymectomy combined with immunotherapy is a preferred treatment with a satisfactory long-term remission rate. Patients with non-thymomatous myasthenia gravis have a much more promising prognosis than the patients with thymomatous myasthenia gravis. However, appropriate caution must be taken to discontinue pharmaceutical therapy as relapse remains a major concern after a patient who has already undergone thymectomy becomes symptom-free.

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

Background

The 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.

Objective

To study the efficacy of thymectomy in achieving remission or minimal manifestation (R/MM) status in patients with non-thymomatous MG.

Methods

Patients 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.

Results

Of 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.

Discussion

When 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.

Glucocorticoids in myasthenia gravis - if, when, how, and how much?

Glucocorticoids (GC) are the most commonly used immune-directed therapy in myasthenia gravis (MG). However, to date, GC have not proven their effectiveness in the setting of a randomized clinical trial that complies with currently accepted standards. The rationale for the use of GC in MG is the autoimmune nature of the disease, which is supported by consistent positive results from retrospective studies. Well-defined recommendations for treatment of MG with GC are lacking and further hampered by inter- and intra-individual differences in the disease course and responses to GC treatment. Uncertainties concerning GC treatment in MG encompass the indication for treatment initiation, exact dosage, dose adjustment in specific conditions (e.g., pregnancy, thymectomy), mode of tapering, and surveillance of adverse events (AE). This review illustrates the mode of action of GC in the treatment for MG, presents the currently available data on GC treatment in MG, and attempts to translate the currently available information into clinical recommendations.

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.

Surgical approaches for stage I and II thymoma-associated myasthenia gravis: feasibility of complete video-assisted thoracoscopic surgery (VATS) thymectomy in comparison with trans-sternal resection

Complete resection could be achieved in virtually all myasthenic patients with Masaoka stage I and II thymoma using the trans-sternal technique. Whether this is appropriate for minimally invasive approach is not yet clear. We evaluated the feasibility of complete video-assisted thoracoscopic surgery (VATS) thymectomy for the treatment of Masaoka stage I and II thymoma-associated myasthenia gravis, compared to conventional trans-sternal thymectomy. We summarized 33 patients with Masaoka stage I and II thymoma-associated myasthenia gravis between April 2006 and September 2011. Of these, 15 patients underwent right-sided complete VATS (the VATS group) by using adjuvant pneuomomediastinum, comparing with 18 patients using the trans-sternal approach (the T3b group). No intraoperative death was found and no VATS case required conversion to median sternotomy. Significant differences between the two groups regarding duration of surgery and volume of intraoperative blood loss (P = 0.001 and P < 0.001, respectively) were observed. Postoperative morbidities were 26.7% and 33.3% for the VATS and T3b groups, respectively. All 33 patients were followed up for 12 to 61 months in the study. The cumulative probabilities of reaching complete stable remission and effective rate were 26.7% (4/15) and 93.3% (14/15) in the VATS group, which had a significantly higher complete stable remission and effective rate than those in the T3b group (P = 0.026 and P = 0.000, respectively). We conclude that VATS thymectomy utilizing adjuvant pneuomomediastinum for the treatment of stage I and II thymoma-associated myasthenia gravis is technically feasible but deserves further investigation in a large series with long-term follow-up.

Ten-year results of thoracoscopic unilateral extended thymectomy performed in nonthymomatous myasthenia gravis

OBJECTIVE

The aim of this study was to analyze the 10-year results of thoracoscopic unilateral extended thymectomy (TUET) performed in nontumoral myasthenia gravis according to the Myasthenia Gravis Foundation of America recommendations.

BACKGROUND DATA

Thoracoscopic unilateral extended thymectomy has the benefits of a minimally invasive approach. Previous data have shown promising midterm results but long-term results were lacking.

METHODS

Two hundred forty patients with nontumoral myasthenia gravis who underwent surgery between 1999 and 2009 were eligible for the study. The mean follow-up was of 67 months (range: 12-125), 134 patients completed follow-up assessments more than 60 months after TUET.

RESULTS

There were 39 males (16.3%) and 201 females (83.7%), with an age range from 8 to 60 years. The mean preoperative disease duration was 21.5 months. All patients underwent preoperative steroid therapy. Anticholinesterase drugs were required for 123 patients (51.3%), and immunosuppressive drugs were required for 87 (36.3%) patients. The pathologic findings were as follows: normal thymus in 13 patients (5.5%), involuted thymus in 65 patients (27%), and hyperplastic thymus in 162 patients (67.5%). The average weight of the thymus was 110 ± 45 g. Ectopic thymic tissue was found in 147 patients (61.3%). There was no mortality, and morbidity consisted of 12 patients (5%). Complete stable remission was achieved in 61% of the patients, and the cumulative probability of achieving complete stable remission was 0.88 at 10 years.

CONCLUSIONS

With zero mortality, low morbidity, and comparable long-term results to open surgery, TUET can be regarded as the best treatment option for patients undergoing surgery for myasthenia gravis.

Myasthenia gravis: a review of available treatment approaches

Patients with autoimmune myasthenia gravis (MG) should be further classified before initiating therapy, as treatment response varies for ocular versus generalised, early onset versus late onset, and acetylcholine receptor antibody positive versus MuSK antibody positive disease. Most patients need immunosuppression in addition to symptomatic therapy. Prednisolone and azathioprine represent first choice drugs, whereas several second choice options are recommended and should be considered. Thymectomy should be undertaken in MG with thymoma and in generalised, early-onset MG. For MG crises and other acute exacerbations, intravenous immunoglobulin (IvIg) and plasma exchange are equally effective and safe treatments. Children and females in child bearing age need special attention regarding potential side effects of immunosuppressive therapy. MG pathogenesis is known in detail, but the immune therapy is still surprisingly unspecific, without a pin-pointed attack on the defined disease-inducing antigen-antibody reaction being available.

Inflammation and epstein-barr virus infection are common features of myasthenia gravis thymus: possible roles in pathogenesis

The thymus plays a major role in myasthenia gravis (MG). Our recent finding of a persistent Epstein-Barr (EBV) virus infection in some MG thymuses, combined with data showing that the thymus is in a proinflammatory state in most patients, supports a viral contribution to the pathogenesis of MG. Aim of this study was to gain further evidence for intrathymic chronic inflammation and EBV infection in MG patients. Transcriptional profiling by low density array and real-time PCR showed overexpression of genes involved in inflammatory and immune response in MG thymuses. Real-time PCR for EBV genome, latent (EBER1, EBNA1, LMP1) and lytic (BZLF1) transcripts, and immunohistochemistry for LMP1 and BZLF1 proteins confirmed an active intrathymic EBV infection, further supporting the hypothesis that EBV might contribute to onset or perpetuation of the autoimmune response in MG. Altogether, our results support a role of inflammation and EBV infection as pathogenic features of MG thymus.

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

Objective

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.

Methods

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.

Results

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).

Conclusions

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.

Current and emerging therapies for the treatment of myasthenia gravis

Myasthenia gravis (MG) is an autoimmmune disease in which autoantibodies to different antigens of the neuromuscular junction cause the typical weakness and fatigability. Treatment includes anticholinesterase drugs, immunosuppression, immunomodulation, and thymectomy. The autoimmune response is maintained under control by corticosteroids frequently associated with immunosuppressive drugs, with improvement in the majority of patients. In case of acute exacerbations with bulbar symptoms or repeated relapses, modulation of autoantibody activity by plasmapheresis or intravenous immunoglobulins provides rapid improvement. Recently, techniques removing only circulating immunoglobulins have been developed for the chronic management of treatment-resistant patients. The rationale for thymectomy relies on the central role of the thymus. Despite the lack of controlled studies, thymectomy is recommended as an option to improve the clinical outcome or promote complete remission. New videothoracoscopic techniques have been developed to offer the maximal surgical approach with the minimal invasiveness and hence patient tolerability. The use of biological drugs such as anti-CD20 antibodies is still limited but promising. Studies performed in the animal model of MG demonstrated that several more selective or antigen-specific approaches, ranging from mucosal tolerization to inhibition of complement activity or cellular therapy, might be feasible. Investigation of the transfer of these therapeutic approaches to the human disease will be the challenge for the future.

Transcervical video-assisted thymectomy: preliminary results of a modified surgical approach

PURPOSE

A number of surgical approaches have been reported for thymectomy, including transsternal, transcervical, a combination of complete transsternal and transcervical, and various video-assisted thoracoscopic surgery techniques. A modified video-assisted transcervical approach to thymectomy is here described.

METHODS

A video-assisted total thymectomy was performed through a 30-mm cervical incision. No hyperextension of the patient's neck or sternal retractor was used. The surgical instruments utilized for the resection were the ones created for the minimally invasive video-assisted thyroidectomy.

RESULTS

Five patients have been operated on so far. The encapsulated gland was removed without any difficulties. No complications occurred. No pain relief was administered after the first 24 h. The patients were discharged within the first two postoperative days. An improvement in clinical symptoms was registered in all patients.

CONCLUSIONS

An advantage of this minimally invasive video-assisted transcervical approach to thymectomy is that the entire operation can be performed without neck hyperextension or permanent sternum elevation. Moreover, the surgical instruments created for minimally invasive video-assisted thyroidectomy enabled us to be very precise and to complete the resection without any postoperative morbidity.

Combined unilateral-thoracoscopic and mediastinoscopic thymectomy

To achieve maximal benefit, after thymic tissue and mediastinal fat were removed by thoracoscopic thymectomy, a transverse cervical incision allowed access to remove fat in the neck. A mediastinoscopy was then performed for removal of the fat in the retrosternal area superior to the innominate vein. In 15 cases, ectopic thymic tissue was found. There were three cases in which the residual superior horns of thymus were found in the neck and three in the retrosternal area. The combined use of a mediastinoscope and a thoracoscope can remove almost all the thymus, including ectopic tissues. Long-term results are still being awaited.