Thymectomy for myasthenia gravis: analysis of controversies--patient management

Enigmatic thymus: Variations in anatomical localisation of thymic tissue as an easily misdiagnosed congenital anomaly in surgical practice

We point out the issue of differential diagnosis regarding the finding of ectopically localised thymic tissue (a thymic cyst) in the neck. Thymic tissue can be found anywhere along its developmental tract of descent, from the angle of the mandible to the upper mediastinum. Disruption of the thymic descent can result in ectopically/abnormally localised islets of accessory thymic tissue, which may undergo cystic changes, as described in a case report by Sun et al. This anatomical variation of the thymus may be clinically misinterpreted as a neoplasm or other congenital anomalies as a branchial cyst, lymphatic malformation or cystic hygroma. The present editorial focuses on the challenge of establishing a diagnosis of ectopically localised tissue of thymus often presented as a lateral cervical mass, especially in the case of cystic variation/degeneration of this thymic tissue. We summarise hypotheses on the origin of such congenital cervical thymic cysts from the point of view of evolutionary history and embryology. We also discuss lesser-known facts about the anatomy, histopathology and developmental biology of the thymus as one of the most enigmatic organs in the human body.

Insights from a Case of Good's Syndrome (Immunodeficiency with Thymoma)

Immunodeficiency with thymoma was described by R.A. Good in 1954 and is also named after him. The syndrome is characterized by hypogammaglobulinemia associated with thymoma and recurrent infections, bacterial but also viral, fungal and parasitic. Autoimmune diseases, mainly pure red cell aplasia, other hematological disorders and erosive lichen planus are a common finding. We describe here a typical case exhibiting all these clinical features and report a detailed immunophenotypic assessment, as well as the positivity for autoantibodies against three cytokines (IFN-alpha, IL-6 and GM-CSF), which may add to known immune abnormalities. A review of the published literature, based on case series and immunological studies, offers some hints on the still unsolved issues of this rare condition.

Critical illness-associated weakness and related motor disorders

Weakness of limb and respiratory muscles that occurs in the course of critical illness has become an increasingly common and serious complication of adult and pediatric intensive care unit patients and a cause of prolonged ventilatory support, morbidity, and prolonged hospitalization. Two motor disorders that occur singly or together, namely critical illness polyneuropathy and critical illness myopathy, cause weakness of limb and of breathing muscles, making it difficult to be weaned from ventilatory support, commencing rehabilitation, and extending the length of stay in the intensive care unit, with higher rates of morbidity and mortality. Recovery can take weeks or months and in severe cases, and may be incomplete or absent. Recent findings suggest an improved prognosis of critical illness myopathy compared to polyneuropathy. Prevention and treatment are therefore very important. Its management requires an integrated team approach commencing with neurologic consultation, creatine kinase (CK) measurement, detailed electrodiagnostic, respiratory and neuroimaging studies, and potentially muscle biopsy to elucidate the etiopathogenesis of the weakness in the peripheral and/or central nervous system, for which there may be a variety of causes. These tenets of care are being applied to new cases and survivors of the coronavirus-2 disease pandemic of 2019. This chapter provides an update to the understanding and approach to critical illness motor disorders.

Transareolar uniportal thoracoscopic extended thymectomy for patients with myasthenia gravis

Background

Transareolar uniportal thoracoscopic extended thymectomy (TUTET) has not been previously reported. We attempted to assess the feasibility and safety of TUTET for male myasthenia gravis (MG) patients.

Patients and methods

From February 2013 to February 2020, 46 men with MG underwent TUTET. All patients were followed up for 12–84 months postoperatively by clinic visits or telephone/e-mail interviews.

Results

All surgeries were completed successfully, with an average operation time of 72.6 min. The mean length of transareolar uniportal incision was 3.0 ± 0.4 cm, and the mean postoperative cosmetic score was 3.1 ± 0.5 at discharge. Three months postoperatively, no patients had an apparent surgical scar on the chest wall or complained of postoperative pain. Substantial amelioration of the disease was achieved in a short period, and several benefits were clear. At the 1-year follow-up, all patients showed a good cosmetic effect and high satisfaction.

Conclusions

TUTET is an effective and safe way for men with MG. The uniportal incision is hidden in the areola with sound cosmetic effects. We believe that TUTET is an acceptable procedure for extended thymectomy.

Risk factors of prolonged ventilation after thymectomy in thymoma myasthenia gravis patients

BACKGROUND

To explore the risk factors for prolonged ventilation after thymectomy in patients with thymoma associated with myasthenia gravis (TAMG).

METHODS

We reviewed the records of 112 patients with TAMG after thymectomy between January 2010 and December 2019 in Peking University People's Hospital. Demographic, pathological, preoperative data and the Anesthesia, surgery details were assessed with multivariable logistic regression analysis to predict the risk of prolonged ventilation after thymectomy. A nomogram to predict the probability of post-thymectomy ventilation was constructed with R software. Discrimination and calibration were employed to evaluate the performance of the nomogram.

RESULTS

By multivariate analysis, male, low vital capacity (VC), Osserman classification (IIb, III, IV), total intravenous anesthesia, and long operation time were identified as the risk factors and entered into the nomogram. The nomogram showed a robust discrimination, with an area under the receiver operating characteristic curve (AUC) of 0. 835 (95% confidence interval [CI], 0.757-0.913). The calibration plot indicated that the nomogram-predicted probabilities compared very well with the actual probabilities (Hosmer-Lemeshow test: P = 0.921).

CONCLUSION

The nomogram is a valuable predictive tool for prolonged ventilation after thymectomy in patients with TAMG.

[Rethymectomy in patients with myasthenia gravis and recurrent thymoma]

OBJECTIVE

To analyze efficacy and safety of rethymectomy in patients with pathology of thymus.

MATERIAL AND METHODS

Nine patients (2 males and 7 females) underwent rethymectomy in the thoracic surgery department of the Hertzen Research Institute of Oncology for the period from March 2009 to December 2019. Initial thymectomy for myasthenia gravis was performed in 6 patients, for thymoma without myasthenia - in 3 patients. Age of patients varied from 27 to 75 years (median 42.8 years). Myasthenia manifested at the age of 25-61 years (median 29.2 years). Period between manifestation and thymectomy varied from 6 to 24 months (median 12.6 months). MGFA grade IIIa was in 1 patient, grade IIIb - in 1, grade IVa - in 1, grade IVb - in 2, grade V - in 1 patient. Rethymectomy was performed via sternotomy in 4 cases, through thoracoscopy - in 5 patients.

RESULTS

Postoperative complications occurred in 2 (22.2%) patients. Biopsy revealed residual thymic tissue in all patients. Median follow-up after rethymectomy was 30.2 months (range 12-132 months). Complete stable remission was achieved in 3 (50.0%) patients, remission - in 2 cases, partial remission - in 1 patient. Median dose of steroids before rethymectomy was 40 mg (range 16-96 mg), median dose after rethymectomy - 8 mg (range 0-24 mg). Differences were significant (p=0.04). All patients operated on for thymoma or recurrence are alive within 12-124 months after rethymectomy.

CONCLUSION

Rethymectomy is a safe and effective treatment option for patients with refractory myasthenia gravis (especially in case of detected residual thymic tissue) or recurrent thymoma. Radical surgery for recurrent thymoma ensures favorable survival.

Video-Assisted Thoracic Surgery Thymectomy: Transpleural Approach

There are several types of minimally invasive approaches for thymectomy, of which the transpleural approach by video-assisted thoracoscopic surgery is particularly useful. In this approach, thymectomy is performed from either side of the thoracic cage. Thoracic surgeons should be familiar with the principles of the procedure, the anatomy of the region, and surgical strategies for successful thymectomy. The details of transpleural thymectomy are discussed herein.

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'.

Autoimmune disorders and paraneoplastic syndromes in thymoma

Thymomas are counted among the rare tumour entities which are associated with autoimmune disorders (AIDs) and paraneoplastic syndromes (PNS) far more often than other malignancies. Through its complex immunological function in the context of the selection and maturation of T cells, the thymus is at the same time highly susceptible to disruptive factors caused by the development and growth of thymic tumours. These T cells, which are thought to develop to competent immune cells in the thymus, can instead adopt autoreactive behaviour due to the uncontrolled interplay of thymomas and become the trigger for AID or PNS affecting numerous organs and tissues within the human body. While myasthenia gravis is the most prevalent PNS in thymoma, numerous others have been described, be they related to neurological, cardiovascular, gastrointestinal, haematological, dermatological, endocrine or systemic disorders. This review article sheds light on the pathophysiology, epidemiology, specific clinical features and therapeutic options of the various forms as well as courses and outcomes of AID/PNS in association with thymomas. Whenever suitable and backed by the limited available evidence, the perspectives from both the thymoma and the affected organ/tissue will be highlighted. Specific issues addressed are the prognostic significance of thymectomy on myasthenia gravis and other thymoma-associated AID/PND and further the impact and safety of immunotherapies on AID and PND relating to thymomas.

Descripción de las características clínicas y la respuesta a tratamiento en pacientes con miastenia grave sin timoma sometidos a timectomía en una institución de alta complejidad de Cali, Colombia, 2010-2017

Introducción. La miastenia grave es una enfermedad autoinmunitaria con una prevalencia mundial de 150 a 250 casos por 1´000.000 de habitantes. El tratamiento recomendado para la miastenia grave sin timoma es la timectomía total, la cual es la única alternativa de curación. Métodos. Se llevó a cabo un estudio descriptivo y retrospectivo de una serie de casos de pacientes adultos con miastenia grave sin timoma sometidos a timectomía, durante el periodo de 2010 a 2017. En el análisis estadístico descriptivo, se utilizaron frecuencias absolutas y porcentajes para las variables cualitativas y, para las variables cuantitativas, se utilizaron la mediana y el rango intercuartílico. Resultados. Veintiocho pacientes con miastenia grave sin timoma se sometieron a timectomía desde el año 2010 hasta el 2017. Se categorizaron según la clasificación del estado posterior a la intervención de la Myasthenia Gravis Foundation of America y se evidenció que 4 (14,3 %) pacientes presentaban remisión completa y el grado 3 de manifestaciones clínicas mínimas fue el más frecuente en 19 (67,9 %); 26 (92,9 %) tuvieron mejoría con respecto al cambio del estado clínico, en 2 (7,1 %) no se documentaron cambios y en ningún paciente hubo empeoramiento, exacerbación o muerte secundaria a la enfermedad. Conclusiones. A lo largo de siete años se practicó timectomía a 28 pacientes con diagnóstico de miastenia grave sin timoma, aproximadamente, en el 15 % de los pacientes hubo remisión completa, el grado 3 de manifestaciones mínimas fue el más frecuente y el 93 % presentó mejoría de su estatus clínico.

Robotic assisted minimally invasive thymectomy with simultaneous bilateral thoracoscopy and contralateral phrenic nerve visualization

Background

Thoracoscopic approaches to thymectomy and anterior mediastinal mass resection has become increasingly common due to the potential for decreased blood loss and hospital length of stay. However, contralateral mediastinal and phrenic nerve visualization if often difficult from these unilateral approaches, which may affect the ability to achieve a full phrenic to phrenic dissection Herein, we present our early experience of robotic assisted minimally invasive thymectomy (RAMIT) with simultaneous bilateral thoracoscopy and contralateral phrenic nerve visualization.

Methods

This was a retrospective review of all sequential patients undergoing RAMIT with simultaneous bilateral thoracoscopy from January 2015 to May 2016. This study was approved by our Institutional Review Board (PRO15080367). Individual patient consent was waived.

Results

Twenty-six patients [median age 58 (range, 29-76) years] were included in this study. Sixteen operations were performed for anterior mediastinal mass, 7 for non-thymomatous myasthenia gravis, and 3 for concurrent myasthenia gravis and thymoma. Median blood loss and hospital stay were 25 mL (range, 3-150 mL) and 3 days (range, 2-8 days), respectively. Twenty-one (80.8%) patients experienced an uncomplicated hospital course. The highest graded complication by Clavien Dindo Classification was a grade III due to pleural effusion requiring drainage via pleural catheter. One patient experienced asymptomatic hemidiaphram palsy postoperatively. There were no 90-day postoperative deaths.

Conclusions

RAMIT with simultaneous bilateral thoracoscopy is a feasible approach that may allow for enhanced visualization and more complete thymic resection compared to existing unilateral minimally invasive operations. Comparative studies and long-term follow up are needed to adequately assess the potential benefits of RAMIT.

Robotic-Extended Rethymectomy for Refractory Myasthenia Gravis: A Case Series

To assess the safety and efficacy of robotic-extended rethymectomy in selected refractory myasthenia gravis (MG) patients with suspected residual thymic tissue. Robotic-extended rethymectomy was performed in 6 MG patients with seropositive acetylcholine receptors (AChR) antibody who had undergone a previous thymectomy (1 cervicotomy, 2 video-assisted thoracoscopic surgeries, and 3 sternotomies). The median observation time before robotic rethymectomy was 108 (24-171) months. The main outcomes were perioperative morbidity, mortality, conversion to open surgery, and clinical outcomes according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS). Before rethymectomy, all patients required immunosuppressants and 5 patients (83.3%) required intravenous immune globulin and/or plasma exchange to control the symptoms. The median specimen weight was 24.5 (14-144) g after rethymectomy, and residual thymic tissue was found in 5 patients (83.3%). No conversion to open surgery or perioperative morbidity and mortality was observed. With a median follow-up time of 46.5 (13-155) months, 3 patients (50%) achieved "improved" and 3 (50%) were "unchanged" according to the MGFA-PIS. Compared with preoperative use, the median daily dose of corticosteroids statistically decreased (25 [7.5-60] vs 0 [0-5] mg, P = 0.002) without significant change in azathioprine use (100 [0-200] vs 50 [0-150] mg, P = 0.360). AChR antibody positive MG patients with a treatment refractory long-term course after thymectomy might have remaining thymic tissue with the 2 commonly associated thymus pathologies, thymoma, and follicular hyperplasia. Robotic-extended rethymectomy might be considered as a safe and beneficial treatment option in these patients.

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.

Independent long-term result of robotic thymectomy for myasthenia gravis, a single center experience

Background

Robotic thymectomy has been suggested a feasible and safe approach for myasthenia gravis (MG). Few investigations have revealed the independent effect of robotic thymectomy without the confounding impact of immunosuppressive (IM) therapy.

Methods

Between May 2009 and December 2012, robotic extended thymectomy was carried out for patients with diagnosis of MG. The clinical data, subsequent neurological therapy and postintervention status were collected.

Results

Data of 37 cases was available for analysis. The mean follow-up was 70.0±13.3 months. The median age was 40 years. Twelve (32.4%) patients kept free of IM therapy, and 25 (67.6%) patients accepted postoperatively. The overall 5-year complete stable remission (CSR) rate was 40.6% and improvement rate was 81.6%. The young (age ≤40) displayed a significant better CSR rate (P=0.015) and a trend of better improvement rate (P=0.050) compared to the old (age >40). Patients without usage of IM therapy showed significant higher CSR rate (P=0.014) and improvement rate (P=0.024) compared to those with usage of IM therapy. Patients with Myasthenia Gravis Foundation of America (MGFA) classes I showed a trend of higher remission rate by multivariate analysis. No significant differences were found for the remission rate according to gender, pathology, and the duration of symptoms.

Conclusions

The mono-therapy of robotic thymectomy may bring with a satisfactory long-term result for part of MG patients. Precision selection and individualized therapy are of the most importance.

Surgical approach in thymectomy: Our experience and review of the literature

Aim

Thymectomy is the main treatment for thymoma and patients with myasthenia gravis (MG). The traditional approach is through a median sternotomy, but, recently, thymectomy through minimally invasive approaches is increasingly performed. Our purpose is an analysis and discussion of the clinical presentation, the diagnostic procedures and the surgical technique. We also consider post-operative complications and results, over a period of 5 years (May 2011–June 2016), in thymic masses admitted in our Thoracic Surgery Unit.

Methods

We analyzed 8 patients who underwent surgical treatment for thymic masses over a period of 5 years. 6 patients (75%) had thymoma, 2 patients (25%) had thymic carcinomas. 2 patients with thymoma (33%) had myasthenia gravis. We performed a complete surgical resection with median sternotomy as standard approach.

Results

One patient (12%) died in the postoperative period. The histological study revealed 6 (75%) thymoma and 2 (25%) thymic carcinomas. Post-operative morbidity occurred in 2 patients (25%) and were: pneumonia in 1 case (12%), atrial fibrillation and pleural effusion in 2 patients (25%). One patient with thymoma type A recurred at skeletal muscle 2-years after surgery.

Conclusions

Thymic malignancies are rare tumors. Surgical resection is the main treatment, but a multimodal approach is useful for many patients. Radical thymectomy is completed removing all the soft tissue in the anterior mediastinum between the two phrenic nerves and this is the most important factor in controlling myasthenia and influencing survival in patients with thymoma. Open (median sternotomy) approach has been the standard approach for thymectomy for the better visualization of the anatomical structures. Actually, video-assisted thoracoscopic surgery (VATS) thymectomy and robotic video-assisted thoracoscopic (R-VATS) approach versus open surgery has an equal if not superior oncological efficacy, better perioperative complications and survival outcomes.

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.

Anesthetic management of robot-assisted thoracoscopic thymectomy

Myasthenia gravis (MG) is a rare disorder involving neuromuscular junction. In conjunction with medical therapy, thymectomy is a known modality of treatment of MG and has shown to increase the probability of remission and overall symptomatic improvement. For minimally invasive thymectomy, video-.assisted thoracoscopic surgery has been the preferred surgical approach till recently. The robotic surgical procedure must necessarily bring new challenges to the anesthesiologists to effectively meet the specific requirements of the technique. At present, there is a paucity of literature regarding the anesthetic concerns of robotic assisted thymectomy, patient in question specifically posed a challenge since different maneuvers and techniques had to be tried to obtain optimum surgical conditions with stable ventilatory and hemodynamic parameters. Concerns of patient positioning and hemodynamic monitoring have also been discussed.

Minimally invasive versus open thymectomy: a systematic review of surgical techniques, patient demographics, and perioperative outcomes

BACKGROUND

Thymectomy is the mainstay of treatment for thymoma and other anterior mediastinal tumors, and is often utilized in the management of patients with myasthenia gravis (MG). While traditionally approached through a median sternotomy, minimally invasive approaches to thymectomy have increasingly emerged. The present systematic review was conducted to compare perioperative and clinical outcomes following minimally invasive thymectomy (MIT) and open thymectomy (OT).

METHODS

Articles were obtained through a PubMed literature search. Comparative studies reporting clinical outcomes following MIT and OT were eligible for inclusion. We selected studies with full text availability, written in the English language, published after 2005 and with at least 15 patients in each arm. A descriptive analysis was performed.

RESULTS

Twenty studies were included, involving a total of 2,068 patients undergoing either MIT (n=838) or OT (n=1,230). Within individual studies, MIT and OT cohorts were well matched with regards to patient age and gender, but there was considerable variation across studies. Resected thymomas were consistently larger in OT groups, with mean diameter significantly larger in five studies (MIT, 29-52 mm; OT, 31-77 mm). MIT was consistently associated with a lower estimated blood loss (MIT, 20-200 mL; OT, 86-466 mL), chest tube duration (MIT, 1.3-4.1 days; OT, 2.4-5.3 days), and hospital length of stay (MIT, 1-10.6 days; OT, 4-14.6 days). There were no consistent differences in rates of perioperative complications, thymoma recurrence, MG complete stable remission, or 5-year survival.

CONCLUSIONS

In appropriately selected patients, MIT may reduce blood loss, chest tube duration, and hospital length of stay, with comparable clinical outcomes compared to OT via median sternotomy.

Endoscopic thymectomy: a neurologist's perspective

Myasthenia gravis (MG) is an autoimmune neuromuscular disease characterized by the presence of antibodies interacting at the neuromuscular junction (NMJ), resulting in loss of strength and severe exhaustibility of striated muscles. The abnormal production of these antibodies is triggered mainly in the thymus, and hence thymectomy in MG is considered a universally recommended treatment in order to improve the symptomatologic condition of this pathology. Currently, minimally invasive thymectomy using the Da Vinci robot system is certainly one of the most innovative techniques, performed in Pisa since 2001. This approach provides a valuable alternative to the traditional thymectomy through median sternotomy. The contribution of a neurologist is fundamental for preoperative patient selection and for the peri-operative clinical assistance in both approaches. We believe that in the robotic approach, the multidisciplinary collaboration between the neurologist, thoracic surgeon and anesthetist is important in reducing perioperative complications and ensuring a higher rate of complete remission or stable clinical improvement of MG.

Thymectomy for myasthenia gravis in children: a comparison of open and thoracoscopic approaches

PURPOSE

Thymectomy is an accepted component of treatment for myasthenia gravis (MG), but optimal timing and surgical approach have not been determined. Though small series have reported the feasibility of thoracoscopic resection, some studies have suggested that minimally invasive methods are suboptimal compared to open sternotomy owing to incomplete clearance of thymic tissue. Here we report the largest series of thymectomies for pediatric myasthenia gravis in the literature to date.

METHODS

A retrospective review of patients undergoing thymectomy for MG between 1990 and 2013 in a tertiary referral hospital was performed. Twelve patients who underwent thoracoscopic thymectomy were compared to 16 patients who underwent open thymectomy via median sternotomy. Postoperative outcomes were determined by electronic chart review in consultation with the treating pediatric neurologist. Disease severities were graded according to a modified Myasthenia Gravis Foundation of America (MGFA) Quantitative MG (QMG) score.

RESULTS

Overall, thoracoscopic resections tended to be performed on patients with earlier and less severe disease than open surgeries. Inpatient length of stay was significantly shorter after thoracoscopic surgery (mean 1.8 vs 8.0 days, p=0.045). The preoperative and postoperative MGFA QMG scores were equivalent between the two groups. Both groups experienced a decrease in disease severity (p<0.001) after median follow-up time of 23 months in the thoracoscopic group and 44 months in the open group.

CONCLUSIONS

Minimally invasive thymectomy for MG in children has increased in popularity as surgeons and neurologists compare the risks and benefits of surgery against other therapies. This analysis suggests that thoracoscopic thymectomy is not inferior to median sternotomy in terms of disease control in this small series, and that the morbidity of the thoracoscopic approach appears sufficiently low to be considered for early stage disease. Low perioperative morbidity and shortened hospital course make thoracoscopic thymectomy an attractive option in centers with sufficient medical and surgical experience.

[Comparative analysis of video-assisted thoracic surgery versus open resection for early-stage thymoma]

BACKGROUND

Video-assisted thoracic surgery (VATS) has significantly developed over the last decade. However, a VATS approach for thymoma remains controversial. The aim of this study was to evaluate the feasibility of VATS thymectomy for the treatment of early-stage thymoma and to compare the outcomes with open resection.

METHODS

A comparative study of 59 patients who underwent surgical resection for early stage thymoma (VATS: 44 and open resection: 15) between 1993 and 2011 was performed. Data of patient characteristics, morbidity, mortality, length of hospital stay, the relationship between miasthenia gravis-thymoma, recurrence, and survival were collected for statistical analysis.

RESULTS

Thymomas were classified according to Masaoka staging system: 38 in stage I (VATS group: 29 and open group: 9) and 21 in stage II (VATS group: 15 and open group: 6). The mean tumor size in the open group was 7.6cm (13-4cm) and in the VATS group 6.9cm (12-2.5cm). The average length of stay was shorter in the VATS group than in the open group (P<.001). No significant differences were found in the estimated recurrence-free and overall 5-year survival rates (96% vs. 100%) between the 2 groups.

CONCLUSIONS

VATS thymectomy for early-stage thymoma is technically feasible and is associated with a shorter hospital stay. The 5-year oncologic outcomes were similar in the open and VATS groups.

Da Vinci robot-assisted system for thymectomy: experience of 55 patients in China

BACKGROUND

Da Vinci robot-assisted thymectomy has been used in the past several years in China, however, practical experience in performing this approach in China remains limited. Thus, the study aimed to evaluate the experience of da Vinci robot-assisted thymectomy in China.

METHODS

From June 2010 to December 2012, 55 patients with diseases of the thymus underwent thymectomy using the da Vinci surgical HD robotic system. The clinical data of the da Vinci robot-assisted thymectomies were compared with the data of video-assisted thoracoscopic thymectomies in the same period.

RESULTS

All da Vinci robot operations were successful. This is a retrospective analysis which demonstrated that compared with video-assisted thoracoscopic thymectomy in the same period, the clinical outcomes of da Vinci robot-assisted thymectomy were not significantly different.

CONCLUSION

The da Vinci robot-assisted thymectomy is a safe, minimally invasive, and convenient operation, and shows promise for general thoracic surgery in China.

Thymectomy in myasthenia gravis: proposal for a predictive score of postoperative myasthenic crisis

OBJECTIVES

Thymectomy plays an important role in patients with myasthenia gravis (MG). This study aimed to explore predictors of postoperative myasthenic crisis (POMC) after thymectomy and to define a predictive score of respiratory failure.

METHODS

The clinical data of 177 patients with MG undergoing thymectomy from January 1995 to December 2011 were retrospectively reviewed. The following factors were analysed in relation to the occurrence of myasthenic crisis: gender, age, body mass index (BMI), anti-acetylcholine receptor-antibody level, bulbar symptoms, comorbidities, duration of symptoms, Osserman-stage, Myasthenia Gravis Foundation of America (MGFA) stage, history of myasthenic crisis, use of immoglobulins or plasmapheresis, kind of therapy, spirometric and blood gas parameters, histology, kind of surgery, non-myasthenic complications and duration of intubation.

RESULTS

Twenty-two patients experienced postoperative respiratory failure after thymectomy. Univariate analysis revealed a correlation with age >60 years (odds ratio (OR) = 1.79, 95% confidence interval (CI) = 1.04-6.78; P = 0.040); Osserman-stage (IIB- OR = 5.16, 95% CI = 1.10-24.18; P = 0.037, III-IV- OR = 8.75, 95% CI = 1.53-50.05; P = 0.015); bulbar symptoms (OR = 7.42, 95% CI = 1.67-32.84; P = 0.008); BMI >28 (OR = 3.99, 95% CI = 1.58-10.03; P = 0.003); preoperative plasmapheresis (OR = 2.97, 95% CI = 1.18-14.04; P = 0.021); duration of symptoms >2 years (OR = 4.00, 95% CI = 1.09-14.762; P = 0.036); extended surgery (OR = 2.52, 95% CI = 1.02-6.22; P = 0.045); lung (OR = 4.05, 95% CI = 1.44-11.42; P = 0.008), pericardial (OR = 3.78, 95% CI = 1.45-9.82; P = 0.006) or pleural resection (OR = 3.23, 95% CI = 1.30-8.03; P = 0.012); Vital Capacity % <80% (OR = 0.20, 95% CI = 0.05-0.82; P = 0.025) and PaCO2 >40 mmHg (OR = 3.76, 95% CI = 1.12-12.68; P = 0.032). Multivariate logistic regression analysis showed that Osserman-stage (IIB- OR = 5.69, 95% CI = 1.09-29.69; P = 0.039 (III-IV- OR = 11.33, 95% CI = 1.67-76.72; P = 0.013), BMI >28 (OR = 3.65, 95% CI = 1.10-12.15; P = 0.035), history of myasthenic crisis (OR = 24.10, 95% CI = 2.34-248.04; P = 0.007), duration of symptoms >2 years (OR = 5.94, 95% CI = 1.12-31.48; P = 0.036) and lung resection (OR = 8.48, 95% CI = 2.18-32.97; P = 0.002) independently predict POMC. Excluding history of preoperative myasthenic crisis (statistically associated with Osserman-stage), we built a scoring system according to the OR of Osserman-stage (I-IIA, IIB, III-IV), BMI (<28, ≥ 28), duration of symptoms (<1, 1-2, >2 years) and association with a pulmonary resection. This model helped in creating four classes with increasing risk of respiratory failure (Group I, 6%; Group II, 10%; Group III, 25%; Group IV, 50%).

CONCLUSIONS

Our model facilitates the stratification of patient risk and prediction of the occurrence of POMC. Moreover, it could help to guide the anaesthesiologist's decision on the duration of intubation. Further studies based on larger series are needed to confirm these preliminary data.

Video-assisted thymectomy with contralateral surveillance camera: a means to minimize the risk of contralateral phrenic nerve injury

OBJECTIVE

Thymectomy for thymoma has traditionally been performed through midsternotomy that provides excellent exposure for a complete and safe resection. Minimally invasive alternatives have not been extensively evaluated for this disease process because data regarding the long-term oncologic effectiveness of these techniques remain to be established. Furthermore, video-assisted surgery as a unilateral approach may compromise the extension of the resection and could cause irreversible damage to the phrenic nerve of the opposite side. We evaluated the clinical feasibility and safety of a bilateral concomitant video-assisted approach with contralateral surveillance camera in patients undergoing thymectomy for thymoma.

METHODS

Four patients (3 females, 1 male) with thymoma causing myasthenia gravis (MG) were operated thoracoscopically at our institute under general anesthesia with double-lumen endotracheal intubation. The patients were placed in a supine position, and a 5-mm 30-degree lens thoracoscope was introduced into the left pleural space. Two other 10-mm working channels were applied. En bloc thymectomy was then performed, including mediastinal and pericardial fat pads, other tissue, and pleura from the level of the thoracic inlet to the diaphragm. A second 5-mm thoracoscope was inserted into the right hemithorax, and it was kept inside during the entire procedure to allow lateral surveillance of the extension and safety of the resection. Carbon dioxide insufflation and valved ports were used.

RESULTS

The duration of the operation was 90 ± 72 minutes. Complete resection was achieved in all patients without any nerve injury. There were no perioperative adverse events. Gradual remission from extremity and ocular weakness was achieved after recovery.

CONCLUSIONS

The ultimate surgical goal of thymectomy is to completely remove the gland and anterior mediastinal tissue without nerve injury. Bilateral concomitant video-assisted thoracic thymectomy with a contralateral surveillance camera was found feasible and safe. Given the capability of our technique to perform a complete and extensive thymectomy associated with less invasiveness and beneficial effects, there seems to be a role for minimally invasive thymectomy in the treatment of thymoma.

Management of juvenile myasthenia gravis

Juvenile myasthenia gravis is an uncommon autoimmune disorder. Its management is not standardized. Juvenile myasthenia gravis is pathophysiologically similar to myasthenia gravis in adults. However, a number of significant particularities related to race, age at onset, severity, and antibody status complicate the management. We summarize the unique clinical features of juvenile myasthenia gravis and review the therapeutic options.

Surgical and neurologic outcomes after robotic thymectomy in 100 consecutive patients with myasthenia gravis

OBJECTIVE

Thymectomy is a well-defined therapeutic option for patients with myasthenia gravis; however, controversies still exist about the surgical approach, indication, and timing for surgery. We reviewed our experience reporting surgical and neurologic results after robotic thymectomy in patients with myasthenia gravis.

METHODS

Between 2002 and 2010, 100 patients (74 female and 26 male; median age, 37 years) underwent left-sided robotic thymectomy using the da Vinci robotic system (Intuitive Surgical, Inc, Sunnyvale, Calif). The Myasthenia Gravis Foundation of America classification was adopted for pre- and postoperative evaluation. Preoperative Myasthenia Gravis Foundation of America class was I in 10% of patients, II in 35% of patients, III in 39% of patients, and IV in 16% of patients.

RESULTS

Median operative time was 120 (60-300) minutes. No death or intraoperative complications occurred. Postoperative complications were observed in 6 patients (6%) (bleeding requiring blood transfusions in 3, chylothorax in 1, fever in 1, and myasthenic crisis in 1). Median hospital stay was 3 days (range, 2-14 days). Histologic analysis revealed 76 patients (76%) with hyperplasia, 7 patients (7%) with atrophy, 8 patients (8%) with small thymomas, and 9 patients (9%) with normal thymus; ectopic thymic tissue was found in 26 patients (26%). Clinical follow-up showed a 5-year probability of complete stable remission and overall improvement of 28.5% and 87.5%. Remission was significantly associated with preoperative I to II Myasthenia Gravis Foundation of America class (P = .02). A significant improvement rate was found in Myasthenia Gravis Foundation of America class I to II (P = .03) and AbAchR+ (P = .04). A high percentage of patients interrupted or reduced their medications.

CONCLUSIONS

Robotic thymectomy is a safe and effective procedure. We observed a neurologic benefit in a great number of patients. A better clinical outcome was obtained in patients with early Myasthenia Gravis Foundation of America class.

Extended transsternal thymectomy for the treatment of ocular myasthenia gravis

BACKGROUND

The optimal treatment for ocular myasthenia gravis (OMG) remains controversial. We conducted a review of the long-term clinical outcomes of Chinese patients with OMG after extended transsternal thymectomy (ETT) to determine the efficacy of this procedure as a treatment for OMG.

METHODS

We reviewed the cases of 115 consecutive patients with OMG who underwent ETT at our Myasthenia Gravis Research Center between January 2006 and December 2008. Extended transsternal thymectomy was done in patients who had thymoma, resistance to pyridostigmine therapy, or relapse after immunosuppressive therapy. The patients' postoperative responses were defined as strict complete remission (SCR), consisting of an asymptomatic status without medication for more than 12 months; general complete remission (GCR), consisting of an asymptomatic status with low-dose single-drug therapy or without medication for more than 12 months; or improvement, consisting of fewer symptoms or less of a need for medication than before surgery.

RESULTS

The overall complication rate was 7.8%. None of the patients experienced a myasthenic crisis, progression to generalized myasthenia gravis, or mortality. Hyperplasia of the thymus was present in 106 of the 115 patients (92.2%). Among 110 patients on whom follow-up was done postoperatively, 29 (26.4%) were in SCR, 64 (58.2%) showed improvement, 7 (6.4%) remained unchanged, and 10 (9.1%) had a worsening of their conditions. Kaplan-Meier analysis revealed rates of GCR of 41.8% at 24 months and 47.3% at 48 months after surgery, and rates of SCR of 24.5% at 24 months and 26.4% at 48 months. Both univariate analysis and multivariate Cox regression analysis revealed that only preoperative duration of illness was positively associated with GCR (p < 0.001).

CONCLUSIONS

The results of the review indicate that ETT is a safe and effective treatment for OMG, especially in patients with illness of shorter duration.

Technique of the transcervical-subxiphoid-videothoracoscopic maximal thymectomy

Background:

The aim of this study is to present the new technique of transcervical-subxiphoid-videothoracoscopic “maximal”thymectomy introduced by the authors of this study for myasthenia gravis.

Materials and Methods:

Two hundred and sixteen patients with Osserman scores ranging from I–III were operated on from 1/9/2000 to 31/12/2006 for this study. The operation was performed through four incisions: a transverse 5–8 cm incision in the neck, a 4–6 cm subxiphoid incision and two 1 cm incisions for videothoracoscopic (VTS) ports. The cervical part of the procedure was performed with an open technique while the intrathoracic part was performed using a video assisted thoracoscopic surgical (VATS) technique. The whole thymus with the surrounding fatty tissue containing possible ectopic foci of the thymic tissue was removed. Such an operation can be performed by one surgical team (the one team approach) or by two teams working simultaneously (two team approach). The early and late results as well as the incidence and localization of ectopic thymic foci have been presented in this report.

Results:

There were 216 patients in this study of which 178 were women and 38 were men. The ages of the patients ranged from 11 to 69 years (mean 29.7 years). The duration of myasthenia was 2–180 months (mean 28.3 months). Osserman scores were in the range of I–III. Almost 27% of the patients were taking steroids or immunosuppressive drugs preoperatively. The mean operative time was 201.5 min (120–330 min) for a one-team approach and it was 146 (95–210 min) for a two-team approach (P < 0.05). While there was no postoperative mortality, the postoperative morbidity was 12%. The incidence of ectopic thymic foci was 68.4%. The rates of complete remission after one, two, three, four and five years of follow-up were 26.3, 36.5, 42.9, 46.8 and 50.2%, respectively.

Conclusion:

Transcervical-subxiphoid-VTS maximal thymectomy is a complete and highly effective treatment modality for myasthenia gravis. The need for sternotomy is avoided while the completeness of the operation is retained.

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.

Robotic-assisted thymectomy

Thymectomy is an established therapy for myasthenia gravis. Minimally invasive surgery for thymectomy has been reported, but not clearly shown to be equivalent to open resection. Robotic-assisted thymectomy may provide the benefit of a full resection of thymic tissue and anterior mediastinal tissue for the treatment of myasthenia gravis by a minimally invasive approach. We present a review of the experience of robotic thymectomy.

Transsternal maximal thymectomy is effective for extirpation of cervical ectopic thymic tissue in the treatment of myasthenia gravis

PURPOSE

Extensive extirpation of cervico-mediastinal adipose tissue increases the chance of removing ectopic thymic tissues, thus potentially improving the prognosis of myasthenia gravis after thymectomy. We sought to increase efficacy and safety of transsternal maximal thymectomy (TSMT).

MATERIALS AND METHODS

Twenty four patients who underwent TSMT from July 2006 to June 2007 were retrospectively reviewed and compared with 73 patients who underwent transsternal extended thymectomy (TSET) from January 2004 to May 2006. Ectopic thymic tissue in additionally excised cervicomediastinal fat tissue was examined histologically.

RESULTS

In TSMT group, operation time, amount of cumulative drainage and duration of drainage were significantly higher than TSET group. However, the difference in hemoglobin count, amount of transfusion, duration of intensive care, postoperative hospital stay, and complication rates were not statistically different. There was no operative mortality in either group. Ectopic thymic tissue was found in 50% of patients. All patients had ectopic thymic tissues in the cervical area. Two patients had additional ectopic tissue in the aortopulmonary window, and 1 patient had ectopic tissue at posterior of the left bracheocephalic vein and lateral of the right phrenic nerve.

CONCLUSION

TSMT is more effective in the extirpation of ectopic thymic tissues than TSET without significant impairment of safety, especially in the cervical area.

Preoperative assessment of thymic veins on multidetector row CT: optimization of contrast material volume

PURPOSE

Preoperative localization of the thymic veins is considered important to prevent intraoperative severe bleeding prior to video-assisted thoracoscopic thymectomy. The purpose of this study was to determine the optimal dose of contrast material for preoperative CT imaging for the detection of thymic veins on the basis of patient weight.

MATERIALS AND METHODS

The records of 31 patients who underwent thymectomy were examined retrospectively. All patients were scanned using an eight-channel multidetector-row computed tomography (CT) scanner at 1.25 mm collimation and a 0.625-mm reconstruction interval. CT scans were obtained after injection of 300 mg I/ml nonionic contrast material at a rate of 2 ml/s. A 90-ml contrast bolus was used for the first 16 consecutive patients (group I), and a 150-ml bolus was used for the following 15 patients (group II). The scan delay was 60 s and 90 s in groups I and II respectively. Two independent radiologists who were blinded to the surgical results evaluated the number of thymic veins observed on preoperative CT, which was later correlated with the actual number of thymic veins clipped during surgery. The responses were analyzed with respect to contrast amount by single bolus and per kilogram of body weight.

RESULTS

Thymic veins were correctly detected in 9 of 16 (56%) patients in group I and 14 of 15 (93%) patients in group II. Thymic vein detection was significantly better in patients who received the >or=2.0 ml/kg contrast medium compared to those who received the 1.00-1.99 ml/kg medium (P < 0.05).

CONCLUSION

An intravenous contrast material volume of 2 ml/kg (300 mg I/ml) is appropriate for the identification of thymic veins on prethymectomy CT.

Inclusion of the transcervical approach in video-assisted thoracoscopic extended thymectomy (VATET) for myasthenia gravis: a prospective trial

BACKGROUND

Because evidence-based data regarding the quality of video-assisted thoracoscopic thymectomy for the treatment of myasthenia gravis are lacking, a prospective trial comparing three different operative approaches was conducted to evaluate their efficacy.

METHODS

This prospective study enrolled 20 consecutive patients with nonthymomatous myasthenia gravis. A series of three approaches for bilateral video-assisted thoracoscopic extended thymectomy (VATET) using the anterior chest wall-lifting method (original), the original method with a flexed-neck position (modified), and the original method with a transcervical approach (final) were prospectively performed in each patient for quantitative and pathologic evaluation of the residual thymus after each approach.

RESULTS

Complete VATET required 242 +/- 48 min, with the transcervical procedure requiring 23 +/- 12 min. After the modified method, the residual thymus in the cervical region was 1.5 cm in size and weighed 0.8 g (0.8% of the entire thymus), as compared with a size of 2.2 cm and a weight of 1.3 g (3.2%) after the original method. Each value is the result of comparison with the final method. Histopathologic studies showed residual tissue in the germinal center as well as Hassall's corpuscles in more than 70% of cases.

CONCLUSION

The findings show that VATET without the transcervical approach could be an immunologically incomplete treatment for myasthenia gravis. Therefore, the transcervical approach should be included in VATET procedures to ensure radicality.