Thymectomy for NonthymomatousMyasthenia Gravis

Robotic surgery for thymic cysts: clinical features, management, and results of a multicentric study

Thymic cysts are rare, radiological diagnosis is often incidental, and cysts seldom assume clinical relevance for symptoms of compression. Thymoma were occasionally found inside both complex and simple thymic cysts. Given the challenges in accurately clinical diagnosing and since the occasionally discovering of thymoma inside both complex and simple thymic cysts, the management of thymic cysts remains controversial. Advancements in surgical tools such as robotics, applied to thymic conditions, could potentially transform the approach to thymic cysts. We report one the largest multicentric series of thymic cysts surgically treated with robotic approach, focusing on preoperative findings and surgical results. Cases were gathered from three Italian thoracic surgery centers with homogeneous clinical practice, significant experience in thymic neoplasms, and thoracic robotic skilled. Surgical intervention was indicated for patients with radiological diagnosis of thymic cysts under the following circumstances: the presence of symptoms, concurrent myasthenia gravis, cysts growing in follow-up, and the complexity of the cyst with suspicion of neoplasm. Data were collected and matched according to postoperative and pathological features to identify potential prognostic factors. Population include 57 patients, 29/28 male/female ratio with mean age of 59.46 ± 11.67 years. The average size of the thymic cysts was 29.14 ± 24.53 ranged between 3 and 150 mm. All patients undergone CT scan and mean of values of density was 25.82 ± 11-82 Hounsfield. Surgical procedures were robotic approach in all case including total/extended thymectomy 35 (61.4%) and cyst resection/partial thymectomy 22 (38.6%). There were no mortality or recurrence. Major complications rate was 5.3%. No correlations were observed between preoperative features and complication. Pathological examination revealed microfoci of thymic tumor in four cases. Robot-assisted surgery for thymic cysts showed excellent early clinical outcomes with low rate of postoperative complications also in case of large lesion. Thymic cysts should not be underestimated due to the risk of coexistent thymic neoplasm.

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.

Analysis of influencing factors of perioperative myasthenic crisis in 387 myasthenia gravis patients without thymoma in a single center

OBJECTIVE

To study the influencing factors of myasthenic crisis in non-thymoma myasthenia gravis (MG) patients during perioperative period.

METHODS

We retrospectively analyzed a total of 387 non-thymoma MG patients who underwent extended thymoma resection in the Department of Thoracic Surgery of Beijing Hospital from February 2011 to December 2021, recorded ASA score, Osserman classification, preoperative course, pyridostigmine dosage, operation method, operation time, and intraoperative blood loss, then analyzed the factors associated with postoperative myasthenic crisis by univariate and multivariate logistic regression.

RESULTS

Osserman classification IIB + III + IV (P < 0.001), history of myasthenic crisis (P = 0.013), pyridostigmine dosage greater than 240 (P < 0.001), ASA score 2 and 3 (P = 0.001) are independent risk factors for myasthenic crisis.

CONCLUSION

Patients with poor Osserman classification, history of myasthenic crisis before surgery, larger preoperative dosage of pyridostigmine, and higher ASA scores should be highly alert to the occurrence of postoperative myasthenic crisis.

Analysis of influencing factors of postoperative myasthenic crisis in 564 patients with myasthenia gravis in a single center

OBJECTIVE

To study the influencing factors of myasthenic crisis in patients with myasthenia gravis during perioperative period.

METHODS

A total of 564 myasthenia gravis (MG) patients who underwent standard expanded resection of thymoma/thymoma in the Department of Thoracic Surgery of Beijing Hospital from January 2011 to March 2022 were retrospectively included in the study. Clinical indicators such as gender, age, thymoma, American Society of Anesthesiologists (ASA) score, operation time, intraoperative blood loss, and some others were recorded.

RESULTS

Osserman-stages IIB + III + IV (odds ratio [OR] 16.091, 95% confidence interval [CI] 5.170-50.076, p value < 0.001), the dosage of pyridostigmine bromide more than 240 mg (OR 6.462, 95% CI 3.110-13.427, p value < 0.001), ASA score 2 and 3 (OR 3.203, 95% CI 1.461-7.020, p value = 0.004), low diffusion lung capacity for carbon monoxide (DLCO%) (OR 0.981, 95% CI 0.963-1.000 p value = 0.049), and blood loss greater than 1000 ml (OR 16.590, 95% CI 1.911-144.011, p value = 0.011) were independent risk factors for myasthenic crisis.

CONCLUSIONS

Patients with poor Osserman stages, higher preoperative dosage of pyridostigmine bromide, higher ASA score, poor pulmonary function (low DLCO%), and more intraoperative bleeding should be highly vigilant for the occurrence of postoperative myasthenic crisis.

Subxiphoid-subcostal versus transthoracic thoracoscopic thymectomy: A safe and feasible approach

Objective

Subxiphoid-subcostal thoracoscopic thymectomy (ST) is an emerging alternative to transthoracic thoracoscopic thymectomy. Potential advantages of ST are the avoidance of intercostal incisions and visualization of both phrenic nerves in their entirety. We describe our experience with ST and compare our results to our previous experience with transthoracic thoracoscopic thymectomy.

Methods

We conducted an institutional review board-exempt retrospective review of all patients who had a minimally invasive thymectomy from August 2008 to October 2021. We excluded patients with a previous sternotomy or radiological evidence of invasion into major vasculature. The ST approach involved 1 subxiphoid port for initial access, 2 subcostal ports on each side, and carbon dioxide insufflation. We used descriptive and comparative statistics on demographic, operative, and postoperative data.

Results

We performed ST in 40 patients and transthoracic thoracoscopic thymectomy in 16 patients. The median age was higher in the ST group (58 years vs 34 years; P = .02). Operative data showed no significant differences in operative times, blood loss, or tumor characteristics. In the ST group, we had 2 emergency conversions for bleeding; 1 ministernotomy, and 1 sternotomy. Postoperative data showed that the ST group had fewer days with a chest tube (1 day vs 2.5 days; P = .02). There were no differences in median length of stay, tumor characteristics, final margins, major complication rate, and opioid requirements between the groups. There has been no incidence of diaphragmatic hernia and no phrenic nerve injuries or mortality in either group.

Conclusions

ST is safe and has similar outcomes compared with transthoracic thoracoscopic thymectomy.

Integrated proteomics and metabolomics analysis reveals hubs protein and network alterations in myasthenia gravis

Background: Thymoma-associated myasthenia gravis (TAMG) is a well-described subtype of Myasthenia gravis (MG). Nevertheless, the detailed proteins and bioprocess differentiating TAMG from TAMG (−) thymoma have remained unclear.

Methods: The proteomics and metabolomics were carried out on serum samples from thymoma group (n = 60, TNMG), TAMG (+) thymoma group (n = 70, TAMG (+)), and TAMG (−) thymomas group (n = 62, TAMG (−)), and controls (n = 159). groups. Proteomics and metabolomics analyses, including weighted gene co-expression network analysis (WGCNA), was conducted to detect the hub proteins and metabolomics processes that could differentiate TAMG (+) from TAMG (−) thymomas. MetaboAnalyst was used to examine the integration of proteomic and metabolomic analysis to differentiate TAMG (+) from TAMG (−) thymomas.

Results: The of module–trait correlation of WGCNA analysis identified KRT1, GSN, COL6A1, KRT10, FOLR2, KRT9, KRT2, TPI1, ARF3, LYZ, ADIPOQ, SEMA4B, IGKV1-27, MASP2, IGF2R was associated with TAMG (+) thymomas. In addition, organismal systems-immune system and metabolism-biosynthesis of other secondary metabolites were closely related to the mechanism of TAMG (+) pathogenesis.

Conclusion: Our integrated proteomics and metabolomics analysis supply a systems-level view of proteome changes in TAMG (+), TAMG (−) thymomas and exposes disease-associated protein network alterations involved in.

Assessment of length of stay and cost of minimally invasive versus open thymectomies in patients with myasthenia gravis in Florida

BACKGROUND

Thymectomy has become a standard component in treatment for myasthenia gravis. The best surgical approach is still subject to debate. Minimally invasive surgery may have a lower mortality and morbidity rate, improved cosmetic results, and equivalent efficacy at improving neurologic symptoms to open approaches. We compared the perioperative outcomes and cost between the two techniques.

METHODS

We queried Florida Inpatient Discharge Dataset for patients who underwent thymectomy and had a primary diagnosis of non-thymomatous myasthenia gravis using International Classification of Diseases (ICD)-9 and ICD-10 codes to carry out this retrospective cohort study. The dates ranged between January 1st, 2013, to December 31st, 2018. We compared outcomes of patients who underwent minimally invasive thymectomy versus those who had open thymectomy.

RESULTS

An open approach was used in 108 patients, whereas a minimally invasive approach was used in 40 patients. Minimally invasive surgery group had a shorter length of stay (3.0 vs. 6.0 days, P<0.001) and had a non-significant lower total cost ($18.4K vs. $22.1K, P=0.186). After adjusting for age and Elixhauser score, length of stay for minimally invasive group was 32% (P=0.01) lower compared to the open surgery group.

CONCLUSIONS

Patients who underwent minimally invasive thymectomy for Myasthenia gravis had a significantly shorter length of stay and a lower, although not significant, overall cost.

Short-term and sustained clinical response following thymectomy in patients with myasthenia gravis

OBJECTIVE

To investigate short- and long-term outcome following thymectomy in patients with acetylcholine-receptor-antibody (AchR-Ab) positive myasthenia gravis (MG).

METHODS

Rates of clinical response (defined as minimal manifestation, pharmacological or complete stable remission) lasting for at least one year were retrospectively analyzed using Cox proportional hazard models. The occurrence of relapses was recorded during follow-up. Clinical factors associated with achieving an initial or a sustained response were analyzed.

RESULTS

94 patients with a median age of 33 years (IQR 22-51), 68% with non-thymomatous MG and 32% with thymoma-associated MG were included. An initial clinical response was reached in 72% (68/94). Neither sex, age at onset, thymus histology, delay to surgery after disease onset, surgical approach, corticosteroid treatment nor clinical severity before thymectomy were significantly associated with achieving this endpoint. During long-term follow-up (median 89.5 months; IQR 46-189.5) only half of the patients with an initial response (34/68) had a sustained response without relapses. No clinical factors predicted if the response would become sustained. In patients without immunosuppressive treatment before thymectomy (n=24), a high AChR-Ab levels reduction rate after thymectomy was associated with a higher likelihood of achieving an initial response (p=0.03).

CONCLUSION

Sustained long-term clinical response of MG patients after thymectomy is significantly lower than the initial response rates would suggest. The observation that none of the evaluated clinical factors was associated with a worse outcome supports the current clinical practice of patient selection for thymectomy. The relative decline of AchR-antibodies after surgery appears to be a promising prognostic marker.

Perioperative Outcomes of Thymectomy in Myasthenia Gravis: A Thoracic Surgery Database Analysis

BACKGROUND

There is clinical equipoise regarding the perioperative and long-term outcomes of autoimmune myasthenia gravis (MG) patients undergoing open vs minimally invasive thymectomy, particularly for non-thymomatous MG. This analysis utilizes multicenter, real-world clinical evidence to assess perioperative complications of open and minimally invasive thymectomy techniques in MG patients.

METHODS

Thymectomy cases 2009-2019 in MG patients were identified in the Society of Thoracic Surgeons General Thoracic Surgery Database. Thymectomies were grouped by surgical technique: transthoracic (TT), transcervical (TC), video-assisted thoracoscopic surgery (VATS), or Robotic VATS (RVATS). Multivariable logistic regression models assessed the association between surgical technique and perioperative complications.

RESULTS

Analysis of non-thymomatous cases (n=1,725) revealed VATS (OR 0.44, CI 0.23-0.83), RVATS (0.73, 0.48-1.26) and TC (0.19, 0.06-0.62) had lower odds of perioperative complications than TT thymectomies. VATS (2.29, 0.63-8.30) and RVATS (4.08, 1.21-3.78) thymectomies had higher odds of perioperative complications than TC. Analysis of thymomatous cases (n=311) found no significant difference in the odds of perioperative complications in TT vs minimally invasive (VATS/RVATS) procedures. The proportion of RVATS procedures increased from 6.43% to 44.27% while TT (56.43% to 34.35%) and TC (19.29% to 6.87%) thymectomies decreased.

CONCLUSIONS

Minimally invasive and TC thymectomies have fewer perioperative complications than TT when performed for non-thymomatous MG. Minimally invasive procedures are increasingly performed for both non-thymomatous and thymomatous disease. There is a nationwide shift towards minimally invasive procedures, even for thymoma resections. Long-term neurological outcome data are needed to determine whether a reduced perioperative risk for minimally invasive thymectomies translates to improved MG outcomes.

Impact of the Surgical Approach to Thymectomy Upon Complete Stable Remission Rates in Myasthenia Gravis: A Meta-analysis

OBJECTIVES

To determine whether the available operative techniques for thymectomy in myasthenia gravis (MG) confer variable chances for achieving complete stable remission (CSR), we performed a meta-analysis of comparative studies of surgical approaches to thymectomy.

METHODS

Meta-analysis was done of all studies providing comparative data on thymectomy approaches, with CSR reported and minimum 3-year mean follow-up.

RESULTS

Twelve cohort studies and 1 randomized clinical trial, containing 1,598 patients, met entry criteria. At 3 years, CSR from MG was similar after video-assisted thoracoscopic (VATS) extended vs both basic (relative risk [RR] 1.00, p = 1.00, 95% confidence interval [CI] 0.39-2.58) and extended (RR 0.96, p = 0.74, 95% CI 0.72-1.27) transsternal approaches. CSR at 3 years was also similar after extended transsternal vs combined transcervical-subxiphoid (RR 1.08, p = 0.62, 95% CI 0.8-1.44) approaches. VATS extended approaches remained statistically equivalent to extended transsternal approaches through 9 years of follow-up (RR 1.51, p = 0.05, 95% CI 0.99-2.30). The only significant difference in CSR rate between a traditional open and a minimally invasive approach was seen at 10 years when the now-abandoned basic (non-sternum-lifting) transcervical approach was compared to the extended transsternal approach (RR 0.4, p = 0.01, 95% CI 0.2-0.8).

CONCLUSIONS

A significant difference in the rate of CSR among various surgical approaches for thymectomy in MG was identified only at long-term follow-up and only between what might be considered the most aggressive approach (extended transsternal thymectomy) and the least aggressive approach (basic transcervical thymectomy). Extended minimally invasive approaches appear to have CSR rates equivalent to those of extended transsternal approaches and are therefore appropriate in the hands of experienced surgeons.

Minimally invasive thymectomy for myasthenia gravis favours left-sided approach and low severity class

OBJECTIVES

Complete thymectomy is a key component of the optimal treatment for myasthenia gravis. Unilateral, minimally invasive approaches are increasingly utilized with debate about the optimal laterality approach. A right-sided approach has a wider field of view, while a left-sided approach accesses potentially more thymic tissue. We aimed to assess the impact of laterality on perioperative and medium-term outcomes, and to identify predictors of a 'good outcome' using standard definitions.

METHODS

We performed a multicentre review of 123 patients who underwent a minimally invasive thymectomy for myasthenia gravis between January 2000 and August 2015, with at least 1-year follow-up. The Myasthenia Gravis Foundation of America standards were followed. A 'good outcome' was defined by complete stable remission/pharmacological remission/minimal manifestations 0, and a 'poor outcome' by minimal manifestations 1-3. Univariate and multivariable logistic regression analyses were performed to assess factors associated with a 'good outcome'.

RESULTS

Ninety-two percent of thymectomies (113/123) were robotic-assisted. The left-sided approach had a shorter median operating time than a right-sided: 143 (interquartile range, IQR 110-196) vs 184 (IQR 133-228) min, P = 0.012. At a median of 44 (IQR 27-75) months, the left-sided approach achieved a 'good outcome' (46%, 31/68) more frequently than the right-sided (22%, 12/55); P = 0.011. Multivariable analysis identified a left-sided approach and Myasthenia Gravis Foundation of America class I/II to be associated with a 'good outcome'.

CONCLUSIONS

A left-sided thymectomy may be preferred over a right-sided approach in patients with myasthenia gravis given the shorter operating times and potential for superior medium-term symptomatic outcomes. A lower severity class is also associated with a 'good outcome'.

Prediction of improvement after extended thymectomy in non-thymomatous myasthenia gravis patients

BACKGROUND

It is popularly believed that myasthenia gravis (MG) patients show acetylcholine receptor antibody (AChRAb) production associated with the thymus (germinal centers, approximately 80%). It has been suggested that thymectomy can remove the area of autoantibody production. This study aimed to determine whether the solid volume of the thymus calculated using three-dimensional (3D) imaging could be used to predict the efficacy of thymectomy. Additionally, the study assessed the relationships of the solid volume with germinal centers, change in the serum AChRAb level, postoperative MG improvement, and prednisolone (PSL) dose reduction extent.

METHODS

This retrospective study included 12 consecutive non-thymomatous MG patients (9 female and 3 male patients), who underwent extended thymectomy at our institution over the last 10 years. The mean patient age was 43.3 ± 14.2 years (range, 12-59 years). The study assessed the number of germinal centers per unit area, change in the serum AChRAb level, postoperative MG improvement, PSL dose reduction extent, and solid volume of the thymus.

RESULTS

The number of germinal centers per unit area was significantly correlated with the solid volume of the thymus. The PSL dose reduction extent tended to be correlated with the solid volume.

CONCLUSIONS

Our findings suggest that the solid volume of the thymus can possibly predict steroid dose reduction. Additionally, the solid volume of the thymus in 3D images is the most important indicator for predicting the efficacy of extended thymectomy.

Comparison between thoracoscopic and open approaches in thymoma resection

Background

To investigate the feasibility and indications of video-assisted thoracic surgery (VATS) in thymoma resection.

Methods

The clinical data of 103 patients undergoing thymoma resection via different approaches [including conventional lateral thoracotomy approach (LTA) in 41 cases, median sternotomy approach (MSA) in 40 cases, and right-sided VATS in 22 cases] were analyzed. Among them, 59, 13, 25, and 6 patients were in Masaoka stage I, II, III, and IV, respectively. Myasthenia gravis (MG) was also found in 54 cases. The patients were followed up for postoperative survival and the improvement in MG. The prognostic indicators of patients undergoing thymoma resection via different surgical approaches (i.e., LTA, MSA, and VATS) were statistically analyzed.

Results

Eight of 103 patients died. Six patients underwent unilateral sacral nerve resection, among whom 4 patients developed respiratory dysfunction, and 3 died. Two patients died of MG after surgery, 1 patient died of tumor recurrence and metastasis, 1 patient died of heart disease, and the cause of death was unknown in the remaining patient. The drainage time was shorter in VATS group than in open groups, along with smaller tumor size. The VATS group also had shorter hospital stay in the whole series and the subgroup without accompanying MG. The improvement in MG showed no significant difference among the three surgical groups. Both 5- and 10-year survival rates were 91% in the entire cohort.

Conclusions

VATS is like a conventional surgeries for improving MG in thymoma patients with accompanying MG. VATS resection can still be considered for thymoma that only invades the mediastinal pleura. For thymomas that have intact capsules and have not invaded mediastinal pleura, MSA surgery shall be performed to ensure patient safety if the anteroposterior diameters of the tumors are large and the masses have produced severe compression of the innominate vein, even if the tumors are still in the Masaoka stage II. For thymomas with large left-to-right diameters and with most parts of the tumors located in the left thoracic cavity, a left-sided approach (either VATS or an open approach) may be used in the absence of MG; if MG accompanies the condition, an MT approach or a bilateral VATS may be considered. In patients with unilateral pericardial phrenic nerve and/or local pericardial involvement, right-sided VATS thymectomy may be considered for thymomas located at the right side and bilateral VATS surgery can be performed for tumors located at the left side. In summary, VATS is feasible for the treatment of thymoma complicated by MG. VATS can be performed in patients with Masaoka stage I, II and (a certain portion of) III thymoma; for some patients with Masaoka stage II thymoma, especially those with compression of the innominate vein, the use of VATS should be cautious.

Technique for Myasthenia Gravis: Subxiphoid Approach

Kido and colleagues in 1999 used for the first time the subxiphoid approach. Recently, video-assisted thoracoscopic surgery (VATS) thymectomy has been improved for the advancement of surgical materials and new instruments. The most important aspect regarding the subxiphoid approach is the possibility to avoid the intercostal nerve damage with the consequence of a decreased use of postoperative analgesics, quite short surgical duration, fast discharge from hospital and a guarantee of successful cosmetics results.

Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis

INTRODUCTION

A randomized trial demonstrated benefit from thymectomy in nonthymomatous acetylcholine receptor (AChR)-antibody positive myasthenia gravis (MG). Uncontrolled observational and histologic studies suggest thymectomy may not be efficacious in anti-muscle-specific kinase (MuSK)-MG.

METHODS

The therapeutic impact of thymectomy was evaluated from data collected for a multicenter, retrospective blinded review of rituximab in MuSK-MG.

RESULTS

Baseline characteristics were similar between thymectomy (n = 26) and nonthymectomy (n = 29) groups, including treatment with rituximab (42% vs. 45%). At last visit, 35% of thymectomy subjects reached the primary endpoint, a Myasthenia Gravis Foundation of America (MGFA) post-intervention status (PIS) score of minimal manifestations (MM) or better, compared with 55% of controls (P = 0.17). After controlling for age at onset of MG, rituximab, prednisone, and intravenous immunoglobulin/plasma exchange treatment, thymectomy was not associated with greater likelihood of favorable clinical outcome (odds ratio = 0.43, 95% confidence interval 0.12-1.53, P = 0.19).

DISCUSSION

Thymectomy was not associated with additional clinical improvement in this multicenter cohort of MuSK-MG patients. Muscle Nerve 59:404-410, 2019.

Feasible and promising modified trans-subxiphoid thoracoscopic extended thymectomy for patients with myasthenia gravis

Background

We have used a promising, minimally invasive thoracoscopic technique of extended thymectomy for patients with myasthenia gravis (MG). The aim of this study was to report our promising technique, a modified single-port trans-subxiphoid approach (MTXA) and to compare perioperative outcomes and effects on MG between our approach and sternotomy.

Methods

We retrospectively reviewed records of all patients undergoing extended thymectomy for MG and/or thymoma between January 1, 2010 and December 31, 2016. The patients were divided into the MTXA group and Sternotomy group.

Results

Of the 50 consecutive patients undergoing extended thymectomy for MG, finally, 13 patients undergoing our MTXA extended thymectomy technique were compared with 20 patients undergoing extended thymectomy via sternotomy. Intraoperative blood loss, postoperative length of stay, and C-reactive protein value on postoperative day 1 were significantly more favorable in the MTXA group than the Sternotomy group (P<0.0001, P=0.0040 and P=0.0073, respectively). Furthermore, no significant differences in the frequency of patients with improvement of their Quantitative Myasthenia Gravis score and/or MG-Activities of Daily Living scale, decrease in the serum level of acetylcholine receptor antibody, and dose reduction of oral prednisone were seen between the two groups.

Conclusions

Our approach to extended thymectomy might be more favorable than sternotomy in patients with MG.

Subxiphoid and subcostal arch "Three ports" thoracoscopic extended thymectomy for myasthenia gravis

Background

The approaches to thoracoscopic thymectomy in myasthenia gravis (MG) are debatable. We developed a novel approach via subxiphoid and subcostal arch, with a significantly shorter duration of operation and hospital stay, less estimated blood loss, and lower postoperative pain.

Methods

From December 2012 to December 2014, 77 myasthenia gravis patients with or without thymoma underwent thoracoscopic extended thymectomy at our hospital. Among them, 41 patients were operated via the subxiphoid and subcostal arch approach and the other 36 via the conventional unilateral approach. The patient outcomes were retrospectively reviewed and evaluated.

Results

The thoracoscopic extended thymectomy was performed safely via the subxiphoid and subcostal arch approach. In this approach, no drainage tube was inserted after operation except in the first two patients. Two of the 41 patients were switched to trans-sternal approach due to the tight adhesion between the thymoma and the left innominate vein. No major complications occurred. Compared with the unilateral approach, the duration of the procedure via subxiphoid and subcostal arch was significantly shorter, with less estimated blood loss, shorter hospital-stay and lower postoperative pain (P<0.001). The cosmetic scores were comparable between the two groups (P=0.369).

Conclusions

The novel subxiphoid and subcostal arch approach is technically feasible and safe. It is an acceptable alternative to conventional thoracoscopic extended thymectomy.

Open source modular ptosis crutch for the treatment of myasthenia gravis

INTRODUCTION

Pharmacologic treatment of Myasthenia Gravis presents challenges due to poor tolerability in some patients. Conventional ptosis crutches have limitations such as interference with blinking which causes ocular surface drying, and frequent irritation of the eyes. To address this problem, a modular and adjustable ptosis crutch for elevating the upper eyelid in Myasthenia Gravis patients has been proposed as a non-surgical and low-cost solution.

AREAS COVERED

This paper reviews the literature on the challenges in the treatment of Myasthenia Gravis globally and focuses on a modular and adjustable ptosis crutch that has been developed by the Medical Device Laboratory at the University of Cape Town.

EXPERT COMMENTARY

The new medical device has potential as a simple, effective and unobtrusive solution to elevate the drooping upper eyelid(s) above the visual axis without the need for medication and surgery. Access to the technology is provided through an open source platform which makes it available globally. Open access provides opportunities for further open innovation to address the current limitations of the device, ultimately for the benefit not only of people suffering from Myasthenia Gravis but also of those with ptosis from other aetiologies.

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.

Thymectomy in Myasthenia Gravis

In recent years, thymectomy has become a widespread procedure in the treatment of myasthenia gravis (MG). Likelihood of remission was highest in preoperative mild disease classification (Osserman classification 1, 2A). In absence of thymoma or hyperplasia, there was no relationship between age and gender in remission with thymectomy. In MG treatment, randomized trials that compare conservative treatment with thymectomy have started, recently. As with non-randomized trials, remission with thymectomy in MG treatment was better than conservative treatment with only medication. There are four major methods for the surgical approach: transcervical, minimally invasive, transsternal, and combined transcervical transsternal thymectomy. Transsternal approach with thymectomy is the accepted standard surgical approach for many years. In recent years, the incidence of thymectomy has been increasing with minimally invasive techniques using thoracoscopic and robotic methods. There are not any randomized, controlled studies which are comparing surgical techniques. However, when comparing non-randomized trials, it is seen that minimally invasive thymectomy approaches give similar results to more aggressive approaches.

A comparison between IVIG and plasma exchange as preparations before thymectomy in myasthenia gravis patients

Myasthenia gravis (MG) is one of the curable neurologic disorders. Various pharmacological therapies are administered for these patients and a thymectomy plays an important role in the therapy of myasthenia gravis, which develops a permanent or relative remission. We investigated the efficacy of intravenous immunoglobulin (IVIG) and plasma exchange (PLEX) as a preparation before thymectomy in patients with MG. This randomized clinical trial was conducted on 24 patients with MG referred for thymectomy, which were randomized to two groups of IVIG and PLEX. The IVIG group received IVIG 1 g/kg/day for two consecutive days and the PLEX group underwent 1-L plasma exchange five times with 5 % albumin replacement fluid, every other day, 10-30 days before the procedure. The duration of hospitalization (day), length of intensive care unit (ICU) stay after surgery (day), length of intubation period (h), duration of surgery (h) and dose of steroid administered were compared between the two groups. Analysis was performed via SPSS version 20. In the PLEX group, post-operative outcomes (duration of hospitalization, ICU length of stay after surgery, intubation period and duration of surgery) were longer than those in the IVIG group. There was significant difference in intubation period (p value = 0.01) and duration of surgery (p value = 0.05) between the PLEX and IVIG groups. The administration of IVIG in comparison to PLEX can be more effective in the preparation before thymectomy in myasthenia gravis patients.

[Thymomectomy by minimally invasive surgery. Comparative study videosurgery versus robot-assisted surgery]

OBJECTIVES

To report the results of minimally invasive surgery in patients with stage I or II thymoma in the Masaoka classification. The reference technique is partial or complete thymectomy by sternotonomy.

METHODS

A retrospective single-center study of a prospective database including all cases of thymoma operated from April 2009 to February 2015 by minimally invasive techniques: either videosurgery (VATS) or robot-assisted surgery (RATS). The surgical technique, type of resection, length of hospital stay, postoperative complications and recurrences were analysed.

RESULTS

Our series consisted of 22 patients (15 women and 7 men). The average age was 53 years. Myasthenia gravis was present in 12 patients. Eight patients were operated on by VATS and 14 patiens by RATS. There were no conversions to sternotomy and no perioperative deaths. The mean operating time was 92min for VATS and 137min for RATS (P<0.001). The average hospital stay was 5 days. The mean weight of the specimen for the VATS group was 13.2 and 45.7mg for the RATS group. Twelve patients were classified Masaoka stage I and 10 were stage II. According to the WHO classification there were 7 patients type A, 5 type AB, 4 type B1, 4 type B2 4 and 2 type B3. As proposed by the Group ITMIG-IASLC in 2015 all patients corresponded to group I. The mean follow-up period was 36 months. We noted 3 major perioperative complications according to the Clavien-Dindo classification: one pneumonia, one phrenic nerve paralysis and one recurrent laryngeal nerve palsy. We observed one case of local recurrence at 22 months. Following surgery 4 patients were treated with radiotherapy and 2 patients with chemotherapy.

CONCLUSIONS

The minimally invasive route is safe, relatively atraumatic and may be incorporated in the therapeutic arsenal for the treatment of Masaoka stage I and II thymoma as an alternative to conventional sternotomy. RATS and VATS are two minimally invasive techniques and the results in the short and medium term are acceptable. The clinical advantages of one over the other are sifficult to establish. RATS could handle larger and more complex lesions in view of the weight and size of the operating instrument.

Neuromuscular junction disorders

Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.

Intraoperative Near-Infrared Fluorescence Imaging of Thymus in Preclinical Models

BACKGROUND

There are currently no thymus-specific contrast agents for biomedical imaging. Thus, finding ectopic thymic tissue during certain operations is extremely difficult. The purpose of the present study was to determine if near-infrared (NIR) fluorescence imaging could provide high sensitivity, real-time identification of thymic tissue during the operation.

METHODS

After initial in vivo screening of a 315-compound NIR fluorophore library for thymic uptake, methylene blue and five different 700-nm emitting candidate molecules were injected into CD-1 mice for quantitation of the signal-to-background ratio as a function of kinetics and dosing. Results were confirmed in 35-kg Yorkshire pigs. Dual-channel NIR imaging was also performed using a variety of 800-nm emitting NIR fluorophores targeted to various tissues in the mediastinum and neck.

RESULTS

The compound Oxazine 170 demonstrated the highest signal-to-background ratio (≥3) for thymic tissue relative to mediastinal fat, heart, lung, muscle, thyroid gland, and parathyroid gland, with peak signal-to-background ratio occurring 4 h after 1 intravenous injection of a human equivalent dose of approximately 7 mg. Simultaneous dual-channel NIR imaging permitted unambiguous identification of the thymus from surrounding tissues, such as endocrine glands and lymph nodes.

CONCLUSIONS

In mouse and pig, NIR fluorescence imaging using Oxazine 170 permits high sensitivity, real-time identification of thymic tissue for surgical procedures requiring its resection or avoidance. The performance of Oxazine 170 for imaging human thymic tissue is currently not known.

Determinants of Complete Resection of Thymoma by Minimally Invasive and Open Thymectomy: Analysis of an International Registry

INTRODUCTION

Minimally invasive thymectomy (MIT) is a surgical approach to thymectomy that has more favorable short-term outcomes for myasthenia gravis than open thymectomy (OT). The oncologic outcomes of MIT performed for thymoma have not been rigorously evaluated. We analyzed determinants of complete (R0) resection among patients undergoing MIT and OT in a large international database.

METHODS

The retrospective database of the International Thymic Malignancy Interest Group was queried. Chi-square and Wilcoxon rank sum tests, multivariate logistic regression models, and propensity matching were performed.

RESULTS

A total of 2514 patients underwent thymectomy for thymoma between 1997 and 2012; 2053 of them (82%) underwent OT and 461 (18%) underwent MIT, with the use of MIT increasing significantly in recent years. The rate of R0 resection among patients undergoing OT was 86%, and among those undergoing MIT it was 94% (p < 0.0001). In propensity-matched MIT and OT groups (n = 266 in each group); however, the rate of R0 resection did not differ significantly (96% in both the MIT and OT groups, p = 0.7). Multivariate analyses were performed to identify determinants of R0 resection. Factors independently associated with R0 resection were geographical region, later time period, less advanced Masaoka stage, total thymectomy, and the absence of radiotherapy. Surgical approach, whether minimally invasive or open, was not associated with completeness of resection.

CONCLUSIONS

The use of MIT for resection of thymoma has been increasing substantially over time, and MIT can achieve rates of R0 resection for thymoma similar to those achieved with OT.

[Thymectomy versus Tumor Resection for Early-stage Thymic Malignancies: A Chinese Alliance for Research in Thymomas (ChART) Retrospective Database Analysis]

背景与目的

探采用中国胸腺肿瘤协作组胸腺肿瘤多中心回顾性数据库，探讨胸腺切除范围对早期胸腺上皮肿瘤预后的影响。

方法

选择Masaoka-Koga分期Ⅰ期、Ⅱ期且术前没有接受新辅助治疗的患者，根据术中胸腺切除程度，分为胸腺切除组及胸腺瘤切除组。对比分析两组患者的临床特点及预后差异。

结果

共有1, 047例患者纳入研究，其中胸腺切除组入组796例患者、胸腺瘤切除组入组251例患者。对于术前合并重症肌无力（myasthenia gravis, MG）的患者，胸腺切除组术后的MG的缓解率明显优于胸腺瘤切除组（91.6% vs 50.0%, P < 0.001）。胸腺切除组的10年总体生存率（overall survival, OS）为90.9%，胸腺瘤切除组的10年OS为89.4%，两者之间没有统计学差异（P=0.732）。胸腺切除组术后复发率为3.7%，胸腺瘤切除组术后复发率为6.2%，两组之间无统计学差异（P=0.149）。进一步分层分析显示，对于Masaoka-Koga Ⅰ期患者，胸腺切除组和胸腺瘤切除组在复发率上没有差异（3.2% vs 1.4%, P=0.259）；然而在Masaoka-Koga Ⅱ期患者中，胸腺切除组的复发率明显低于胸腺瘤切除组的复发率（2.9% vs 14.5%, P=0.001）。

结论

胸腺切除是治疗胸腺上皮肿瘤的标准手术方式，特别是对于Masaoka-Koga Ⅱ期及合并MG的患者。

Outcomes of thoracoscopic thymectomy in patients with juvenile myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune disorder of the postsynaptic neuromuscular junction resulting in fatigability of voluntary muscles. There has been increasing evidence supporting thymectomy for MG in adults, and evidence for the role of surgery in pediatric age groups is increasing. The purpose of this study is to describe the outcomes of our patients with juvenile MG undergoing thoracoscopic thymectomy.

MATERIAL AND METHODS

All patients with juvenile MG who underwent thoracoscopic thymectomy at Phoenix Children's Hospital between 1999 and 2014 were included. Patients were diagnosed by their treating neurologist. An Osserman and Genkins criterion was used to classify the severity of the disease and DeFilippi classification was used to assess remission.

RESULTS

Twelve patients underwent thoracoscopic thymectomy for juvenile MG during the time frame studied. Nine (75%) patients had an Osserman stage of IIB, with only two patients with ocular disease. There were no conversions to an open procedure. Seven (59%) patients had normal thymic histology, 4 (33%) had evidence of follicular hyperplasia and one (8%) had involutional changes. The median length of hospital stay was 2days (range 1-5days). There was no 30-day postoperative morbidity, reoperations or mortality. The median length of follow-up was 31months (range, 4-91months) and at the time of their last follow-up; all 12 (100%) patients had a DeFilippi Classification of 3 or better.

CONCLUSION

Surgery for MG in children is indicated for antibody-receptor-positive patients with moderate to severe disease. Thoracoscopic thymectomy is a safe and acceptable treatment for juvenile MG with good disease control. The low morbidity and shorter hospital duration make it an excellent option for consideration.

Thymectomy versus tumor resection for early-stage thymic malignancies: a Chinese Alliance for Research in Thymomas retrospective database analysis

BACKGROUND

To evaluate the surgical outcomes of tumor resection with or without total thymectomy for thymic epithelial tumors (TETs) using the Chinese Alliance for Research in Thymomas (ChART) retrospective database.

METHODS

Patients without preoperative therapy, who underwent surgery for early-stage (Masaoka-Koga stage I and II) tumors, were enrolled for the study. They were divided into thymectomy and thymomectomy groups according to the resection extent of the thymus. Demographic and surgical outcomes were compared between the two patients groups.

RESULTS

A total of 1,047 patients were enrolled, with 796 cases in the thymectomy group and 251 cases in the thymomectomy group. Improvement rate of myasthenia gravis (MG) was higher after thymectomy than after thymomectomy (91.6% vs. 50.0%, P<0.001). Ten-year overall survival was similar between the two groups (90.9% after thymectomy and 89.4% after thymomectomy, P=0.732). Overall, recurrence rate was 3.1% after thymectomy and 5.4% after thymomectomy, with no significant difference between the two groups (P=0.149). Stratified analysis revealed no significant difference in recurrence rates in Masaoka-Koga stage I tumors (3.2% vs. 1.4%, P=0.259). However in patients with Masaoka-Koga stage II tumors, recurrence was significantly less after thymectomy group than after thymomectomy (2.9% vs. 14.5%, P=0.001).

CONCLUSIONS

Thymectomy, instead of tumor resection alone, should still be recommended as the surgical standard for thymic malignancies, especially for stage II tumors and those with concomitant MG.

Video-assisted thoracoscopic surgery versus sternotomy in thymectomy for thymoma and myasthenia gravis

Thymectomy involves the removal of all the soft tissue in the pre-vascular plane of the anterior mediastinum between the two phrenic nerves. Surgical success in controlling myasthenia and the most important factor influencing survival in patients with thymoma depends on complete clearance of thymic tissue. Currently there is a perception that the open (median sternotomy) approach offers better visualisation of the thymic tissue. This perceived advantage is thought to justify the invasive nature of the procedure associated with increased morbidity. Video-assisted thoracoscopic surgery (VATS) for thymectomy has evolved significantly over the last decade, including bilateral and unilateral VATS (either left or right) approaches. The laterality of the approach remains largely on surgeon preferences, with the decision influenced by their experience and training. VATS offers superior illumination and magnification, particularly with the availability of advanced cameras with variable angles that provide better exposure and lighting of the operative field. The use of three-dimensional-operating imaging has also revolutionised the VATS technique. VATS thymectomy is a superior and radical technique in minimising access trauma and removing all thymic tissue that may be scattered in the anterior mediastinum and cervical fat. Other advantages of VATS include less intraoperative blood loss, early removal of chest drains, less requirement for blood products, decreased inflammatory cytokine response, shorter hospital stay and superior cosmesis. There is also a decreased risk of respiratory and cardiac related complications compared to the open (sternotomy) technique. Furthermore, no significant difference has been found in long-term complications and survival rate between VATS and open approaches. Subsequently, the VATS approach should be encouraged as more surgeons are adopting the minimally invasive practice as routine.

Overcoming challenges in the diagnosis and treatment of myasthenia gravis

In recent years, the discovery of new autoantigens and the use of sensitive assays have expanded the clinical spectrum of myasthenia gravis (MG). In particular, antibodies binding to clustered acetylcholine receptors and to the low-density lipoprotein receptor-related protein 4 have not only bridged a significant gap in diagnosis but also have relevant clinical implications. MG management includes different therapeutic options, from symptomatic agents as the only therapy in mildly affected cases to combined long-term immunosuppression and thymectomy in patients with severe disabling disease. MG biological diversity can influence the response to therapies and should be taken into account when planning treatment. Biologic agents are promising, though their use is currently limited to patients with refractory disease.

Perioperative management in myasthenia gravis: republication of a systematic review and a proposal by the guideline committee of the Japanese Association for Chest Surgery 2014

Thymectomy is regarded as a useful therapeutic option for myasthenia gravis (MG), though perioperative management in MG patients is largely empirical. While evidence-based medicine is limited in the perioperative management of MG patients, treatment guidelines are required as a benchmark. We selected issues faced by physicians in clinical practice in the perioperative management of extended thymectomy for MG, and examined them with a review of the literature. The present guidelines have reached the stage of consensus within the Japanese Association for Chest Surgery.

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.