Myasthenia gravis: recommendations for clinical research standards. Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America

[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.

Serum uric acid levels in patients with myasthenia gravis are inversely correlated with disability

Uric acid (UA), the final product of purine metabolism, has been reported to be reduced in patients with various neurological disorders and is considered to be a possible indicator for monitoring the disability and progression of multiple sclerosis. However, it remains unclear whether there is a close relationship between UA and myasthenia gravis (MG), or whether UA is primarily deficient or secondarily reduced because of its peroxynitrite scavenging activity. We investigated the correlation between serum UA levels and the clinical characteristics of MG. We assessed 338 serum UA levels obtained in 135 patients with MG, 47 patients with multiple sclerosis, and 156 healthy controls. In addition, we compared serum UA levels when MG patients were stratified according to disease activity and classifications performed by the Myasthenia Gravis Foundation of America, age of onset, duration, and thymus histology (by means of MRI or computed tomography). MG patients had significantly lower serum UA levels than the controls (P<0.001). Moreover, UA levels in patients with MG were inversely correlated with disease activity and disease progression (P=0.013). However, UA levels did not correlate significantly with disease duration, age of onset, and thymus histology. Our findings suggest that serum level of UA was reduced in patients with MG and serum UA might be considered a surrogate biomarker of MG disability and progression.

Response to treatment of myasthenia gravis according to clinical subtype

Background

We have previously reported using two-step cluster analysis to classify myasthenia gravis (MG) patients into the following five subtypes: ocular MG; thymoma-associated MG; MG with thymic hyperplasia; anti-acetylcholine receptor antibody (AChR-Ab)-negative MG; and AChR-Ab-positive MG without thymic abnormalities. The objectives of the present study were to examine the reproducibility of this five-subtype classification using a new data set of MG patients and to identify additional characteristics of these subtypes, particularly in regard to response to treatment.

Methods

A total of 923 consecutive MG patients underwent two-step cluster analysis for the classification of subtypes. The variables used for classification were sex, age of onset, disease duration, presence of thymoma or thymic hyperplasia, positivity for AChR-Ab or anti–muscle-specific tyrosine kinase antibody, positivity for other concurrent autoantibodies, and disease condition at worst and current. The period from the start of treatment until the achievement of minimal manifestation status (early-stage response) was determined and then compared between subtypes using Kaplan-Meier analysis and the log-rank test. In addition, between subtypes, the rate of the number of patients who maintained minimal manifestations during the study period/that of patients who only achieved the status once (stability of improved status) was compared.

Results

As a result of two-step cluster analysis, 923 MG patients were classified into five subtypes as follows: ocular MG (AChR-Ab-positivity, 77%; histogram of onset age, skewed to older age); thymoma-associated MG (100%; normal distribution); MG with thymic hyperplasia (89%; skewed to younger age); AChR-Ab-negative MG (0%; normal distribution); and AChR-Ab-positive MG without thymic abnormalities (100%, skewed to older age). Furthermore, patients classified as ocular MG showed the best early-stage response to treatment and stability of improved status, followed by those classified as thymoma-associated MG and AChR-Ab-positive MG without thymic abnormalities; by contrast, those classified as AChR-Ab-negative MG showed the worst early-stage response to treatment and stability of improved status.

Conclusions

Differences were seen between the five subtypes in demographic characteristics, clinical severity, and therapeutic response. Our five-subtype classification approach would be beneficial not only to elucidate disease subtypes, but also to plan treatment strategies for individual MG patients.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Improvement of quality of life after therapeutic plasma exchange in patients with myasthenic crisis

INTRODUCTION

We sought to evaluate quality of life patients with myasthenic crisis before and after therapeutic plasma exchange.

MATERIALS AND METHODS

In our study we conducted an assessment of the quality of life with the use of the questionnaire SF-36, when executed eleven therapeutic plasma exchange. The assessment was made on baseline and after 4 weeks. We also did neurological clinical evaluation before and after TPE.

RESULTS

Patients in the study showed significant improvement in quality of life after performed therapeutic plasma exchange. The changes were observed in physical functioning, which confirmed the results of the statistical significance of p<0.05. In the analysis, the assessment of mental functioning not obtained the results of statistical significance, but the results also showed improvement in self-assessment. We observed high correlation between general health and physical mental functioning, between the role limitations due to physical health problems and role limitations due to emotional problems, and general health perception and bodily pain.

CONCLUSIONS

Therapeutic plasma exchange significantly improves the quality of life of patients with myasthenia gravis during the crisis.

Effect of Gender, Disease Duration and Treatment on Muscle Strength in Myasthenia Gravis

INTRODUCTION

The aim of this observational, cross-sectional study was to quantify the potential presence of muscle weakness among patients with generalized myasthenia gravis (gMG). The influence of gender, treatment intensity and disease duration on muscle strength and disease progression was also assessed.

METHODS

Muscle strength was tested in 8 muscle groups by manual muscle testing and by hand-held dynamometry in 107 patients with gMG and 89 healthy age- and gender-matched controls. Disease duration, severity and treatment history were reviewed and compared with muscle strength.

RESULTS

Patients had reduced strength in all tested muscle group compared to control subjects (p<0.05). Women with gMG were stronger than men (decrease in strength 22.6% vs. 32.7% in men, P<0.05). Regional differences in muscle weakness were also evident, with proximal muscles being more affected. Interestingly, muscle strength did not correlate with disease duration and treatment intensity.

CONCLUSIONS

The results of this study show that in patients with gMG; 1) there is significant muscle weakness, 2) muscle weakness is more pronounced in men than women, 3) shoulder abductors, hip flexors, and neck muscles are the most affected muscle groups and 4) disease duration or treatment intensity alone are not predictors of loss of muscle strength in gMG.

Prevalence and impact of autoimmune thyroid disease on myasthenia gravis course

OBJECTIVES

Autoimmune thyroid diseases (ATDs) frequently accompany myasthenia gravis (MG) and may influence its course. We aimed to determine the association and impact of ATD with early- (<50 years), late-onset MG, or thymoma-MG.

MATERIALS AND METHODS

Prevalence of ATD was measured in a cross-sectional study of 343 consecutive patients with MG (236 F, 107 M) aged 4-89 years; 83.8% were seropositive, in 2.9%, anti-MuSK antibodies were detected. Concentrations of antithyroid peroxidase antibodies, antithyroglobulin antibodies, antithyrotropin receptor antibodies, and TSH level were measured in all patients. MG clinical course, treatment received, and treatment results were evaluated.

RESULTS

Autoimmune thyroid diseases were diagnosed in 92 (26.8%) of MG patients including 4.4% with Graves (GD), 9% with Hashimoto thyroiditis (HT), and 13.4% with antithyroid antibodies only. GD patients had ocular symptoms more often than patients with antithyroid antibodies or HT (p = .008). ATD prevalence was comparable in MG with early and late onset, while non-ATDs were more frequent in thymoma-MG (p = .049). Immunosuppressive therapy was less frequently needed in the patients with MG and ATD, indirectly indicating milder MG course (p = .005). Risk of myasthenic crisis and the results of treatment did not differ between patients with and without ATD.

CONCLUSIONS

Autoimmune thyroid diseases are frequently accompanied by early-and late-onset MG, while thymoma-MG is related to higher risk of non-ATD. Myasthenia coexisting with ATD follows milder course than MG alone.

Epidemiology of myasthenia gravis in Northern Portugal: Frequency estimates and clinical epidemiological distribution of cases

INTRODUCTION

In this study we estimated the prevalence, incidence, and mortality of myasthenia gravis (MG) in northern Portugal and characterized the clinical features of the patients identified.

METHODS

We used 2 data sources: clinical records from the hospitals and pyridostigmine prescription registers.

RESULTS

On December 31, 2013, we estimated a point prevalence of 111.7 patients per million population. The highest prevalence was observed in the group >65 years of age, especially in men (288.1 per million). During 2013, we estimated an incidence rate of 6.3 per million per year. Among women, the incidence rate was highest in the 15-49-year age group; in men, incidence increased with age up to 22.1 per million in those >65 years old. The MG-related mortality rate was 0.5 per million.

CONCLUSIONS

These figures are in keeping with similar studies and emphasize the importance of diagnosis and management of MG in elderly populations. Muscle Nerve 54: 413-421, 2016.

Thymectomy for Myasthenia Gravis: Prognostic Factors in 70 Patients

Thymectomy has become increasingly accepted as an efficacious procedure for myasthenia gravis, with high rates of complete clinical remission. Predictors of the response to thymectomy for myasthenia gravis vary in the literature. We retrospectively reviewed the clinical records of 70 patients (63% female; mean age, 38 years) diagnosed with myasthenia gravis from August 1993 to August 2004, to determine the factors predicting outcome. Complications occurred in 20%, but there was no hospital mortality. Complete clinical remission was obtained postoperatively in 47%. Our results indicate that patients with less than 1 year's duration of disease have a better prognosis, and Osserman stages I, IIa, and IIb are also associated with higher clinical remission rates. Female patients have a better prognosis than males, and the younger the patient the better the outcome. Thymectomy is indicated for myasthenia gravis as early as possible in the course of the disease.

Increased frequency of thymic T follicular helper cells in myasthenia gravis patients with thymoma

BACKGROUND

To investigate the presence of T follicular helper (TFH) cells and their associated molecules in myasthenia gravis (MG) patients with thymoma.

METHODS

TFH cells are detected in thymus around the thymoma region of 50 patients and atrophic thymus in 10 patients as control. The percentage of TFH cells among CD4(+) T cells and the expression level of surface markers CXC chemokine receptor 5 (CXCR5), inducible co-stimulator (ICOS), programmed cell death 1 and the cytoplasmic marker B cell lymphoma 6 (Bcl-6) were analyzed by immunohistochemistry (IHC) staining, immunofluorescence (IF) and western blotting (WB).

RESULTS

Higher percentage of thymic TFH cells was found in MG patients with thymoma compared with both thymoma patients without MG and control group. The expression levels of the four markers in thymoma of MG patients were significantly higher than thymoma patients without MG and control group. No significant difference was found in the levels of programmed cell death 1 (PD-1) and Bcl-6 between thymoma patients without MG and the control, while the levels of CXCR5 and ICOS in thymoma patients without MG were higher than control group.

CONCLUSIONS

These results suggested thymic TFH cells might involve in the pathogenesis of MG with thymoma. However, it needs further study to test if the inhibition of the function of TFH cells could effectively alleviate the severity of MG.

Left- and right-sided video-assisted thoracoscopic thymectomy exhibit similar effects on myasthenia gravis

BACKGROUND

Unilateral video-assisted thoracoscopic (VATS) thymectomy features less operative trauma, improved cosmesis, and similar efficiency compared with transsternal (TS) thymectomy for treatment of patients with myasthenia gravis (MG). Unilateral VATS thymectomy can be easily performed from either side of the thorax, because thymus is located in the middle of mediastinum. Nevertheless, the side that provides better outcomes remains controversial. This study presents our experience on treatments for MG and reveals the differences between the unilateral VATS thymectomy performed on each side.

METHODS

Eighty-one consecutive patients with MG who underwent TS or VATS thymectomy on either side between January 2003 and December 2012 were enrolled in the study. Clinicopathologic data and surgical outcomes were retrospectively analyzed and compared among different surgical approaches.

RESULTS

TS thymectomy was administered in 50 patients, whereas unilateral VATS approaches were performed on the remaining 31 patients, 15 on the left side and 16 on the right side. The VATS group exhibited a significantly shorter surgery duration (P<0.001), less intraoperative blood loss (P=0.009), shorter postoperative hospital stay (P=0.025), smaller thoracic drainage volume (P=0.033), shorter thoracic drainage duration (P=0.006), and less postoperative complications (P<0.001) compared with the TS group. However, disease remission rates did not significantly differ among the groups (P=0.988). The left-sided group exhibited considerably longer thoracic drainage duration than the right-sided group (P=0.041). Moreover, surgical time (P=0.736), intraoperative blood loss (P=0.281), postoperative hospital stay (P=0.599), thoracic drainage volume (P=0.571), postoperative complications (P=0.742) and therapeutic effect (P=1.000) did not significantly differ among the groups. Multivariate analysis revealed that the ocular type of MG is the only independent factor for clinical remission (P=0.002).

CONCLUSIONS

Unilateral VATS thymectomy can reduce surgical risks and shorten hospitalization duration without threatening the therapeutic effect. This technique can be safely and effectively performed by experienced surgeons in either side of the thorax.

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.

Multi-institutional European experience of robotic thymectomy for thymoma

BACKGROUND

Robotic thymectomy for early-stage thymomas has been recently suggested as a technically sound and safe approach. However, due to a lack of data on long term results, controversy still exists regarding its oncological efficacy. In this multi-institutional series collected from four European Centres with high volumes of robotic procedures, we evaluate the results after robot-assisted thoracoscopic thymectomy for thymoma.

METHODS

Between 2002 and 2014, 134 patients (61 males and 73 females, median age 59 years) with a clinical diagnosis of thymoma were operated on using a left-sided (38%), right-sided (59.8%) or bilateral (2.2%) robotic approach. Seventy (52%) patients had associated myasthenia gravis (MG).

RESULTS

The average operative time was 146 minutes (range, 60-353 minutes). Twelve (8.9%) patients needed open conversion: in one case, a standard thoracoscopy was performed after robotic system breakdown, and in six cases, an additional access was required. Neither vascular and nerve injuries, nor perioperative mortality occurred. A total of 23 (17.1%) patients experienced postoperative complications. Median hospital stay was 4 days (range, 2-35 days). Mean diameter of resected tumors was 4.4 cm (range, 1-10 cm), Masaoka stage was I in 46 (34.4%) patients, II in 71 (52.9%), III in 11 (8.3%) and IVa/b in 6 (4.4%) cases. At last follow up, 131 patients were alive, three died (all from non-thymoma related causes) with a 5-year survival rate of 97%. One (0.7%) patient experienced a pleural recurrence.

CONCLUSIONS

Our data suggest that robotic thymectomy for thymoma is a technically feasible and safe procedure with low complication rates and short hospital stays. Oncological outcome appears to be good, particularly for early-stage tumors, but a longer follow-up period and more cases are necessary in order to consider this as a standard approach. Indications for robotic thymectomy for stage III or IVa thymomas are rare and should be carefully evaluated.

Seropositivity for West Nile Virus Antibodies in Patients Affected by Myasthenia Gravis

BACKGROUND

Myasthenia gravis (MG) is an autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles. Specific auto-antibodies against acetylcholine receptor (AChR) are present in the majority of MG patients, although the main cause behind its development still remains unclear. Recently MG development following West Nile virus (WNV) infection has been described in patients without any earlier evidence of MG. It is known that infectious agents trigger immune response and occasionally initiate autoimmune disease. WNV, the causative agent of both benign illness and neuroinvasive disease, has become endemic in many countries in all continents.

METHODS

In the present study, 29 patients (15 males and 14 females, 19 - 78 years old) with confirmed diagnosis of MG and elevated levels of AChR autoantibodies were screened for the presence of serum anti-WNV antibodies and compared to a similar population affected by different autoimmune diseases. Indirect immunofluorescent antibody technique was used to evaluate the reaction of patients' sera on cells infected by WNV.

RESULTS

Positive fluorescent signals for anti-WNV IgG were obtained in 17% of MG patients, although no clinical manifestations related to WNV infection were reported. These results are in agreement with previous data and appear of great interest in the understanding of the pathogenic autoimmune mechanisms at the bases of MG development.

CONCLUSION

As already observed in other human autoimmune diseases, pathogen-triggered autoimmunity could be involved in MG by breaking immunological self-tolerance through possible mechanisms of molecular mimicry between virus proteins and AChR subunits. In predisposed individuals, WNV infection could also represent an additional risk factor to initiate MG.

Low antioxidant status of serum bilirubin, uric acid, albumin and creatinine in patients with myasthenia gravis

OBJECTIVE

Oxidative stress and low antioxidant status play a major role in the pathogenesis of inflammatory and autoimmune diseases. Myasthenia gravis (MG) is an autoimmune condition targeting the neuromuscular junction, and its antioxidant status is still controversial. Our study aimed to investigate the correlation between the clinical characteristics of MG and the serum antioxidant status of bilirubin (Tbil, Dbil and Ibil), uric acid, albumin and creatinine.

MATERIALS AND METHODS

We measured serum antioxidant molecule levels of bilirubin (Tbil, Dbil and Ibil), uric acid, albumin and creatinine in 380 individuals, including 166 MG and 214 healthy controls.

RESULTS

We found that MG patients had significantly lower serum levels of bilirubin (Tbil, Dbil and Ibil), uric acid, albumin and creatinine than healthy controls, whether male or female. Moreover, it was also shown in our study that uric acid, albumin and creatinine levels in patients with MG were correlated with disease activity and classifications performed by the Myasthenia Gravis Foundation of America.

CONCLUSION

Our findings demonstrated that serum levels of bilirubin (Tbil, Dbil and Ibil), uric acid, albumin and creatinine were reduced in patients with MG. This suggested an active oxidative process in MG patients who had low antioxidant status.

Disease specific enrichment of circulating let-7 family microRNA in MuSK+ myasthenia gravis

Myasthenia gravis (MG) patients with antibodies against the muscle specific tyrosine kinase (MuSK+) have predominantly involvement of cranio-bulbar muscles and do not display thymus pathology, as do acetylcholine receptor antibody seropositive (AChR+) MG patients. In search of novel biomarkers for MuSK+ MG, we evaluated circulating serum microRNAs. Four analyzed microRNAs were specifically elevated in MuSK+ MG patient serum samples: let-7a-5p, let-7f-5p, miR-151a-3p and miR-423-5p. The circulating microRNA profile in MuSK+ MG differs from the profile previously observed in the serum of AChR+ MG, thus indicating the etiological difference between these two entities. We propose that the identified microRNAs could serve as potential serum biomarkers for MuSK+ MG.

Clinical Outcomes of Myasthenia Gravis with Thymoma and Thymic Hyperplasia Undergoing Extended Transsternal Thymectomy: A Single-Center Experience

BACKGROUND

Despite the widespread use of thymectomy in myasthenia gravis (MG) patients, it has remained controversial as to whether this procedure is of a similar efficacy and clinical outcome among MG patients with thymoma and thymic hyperplasia.

AIM

We sought to determine the long-term clinical outcomes of MG patients who received extended transsternal thymectomy associated with pyridostigmine and prednisolone postoperatively.

MATERIALS AND METHODS

In a retrospective study from January 1999 to December 2013, MG patients who underwent thymectomy were followed up. Out of 41 MG patients admitted in our center, 25 patients had undergone thymectomy adjunctive to pyridostigmine and prednisolone therapy postoperatively. The primary endpoints included improvement in individual diplopia, ptosis, dysphagia, dysarthria, dyspnea, and limb weakness. In addition, according to the MG Foundation of America (MGFA) criteria, response to therapy was defined as complete stable remission (CSR), pharmacologic remission (PR), and minimal manifestation (MM) as secondary endpoints.

RESULTS

Majority of the patients were male (60%) and the mean age of the patients was 32.2 ± 13.9 years. Fifteen (60%) and 10 patients (40%) had thymoma and thymic hyperplasia, respectively. All the patients were followed up during a mean period of of 86.9 ± 50.3 months (minimum 10 months and maximum 168 months). The rates of CSR, PR, and MM were comparable between the thymoma and thymic hyperplasia groups (P = 0.584). Based on the Kaplan Meier analysis, the probabilities of CSR, PR, and MM were not significantly different between patients with thymoma and thymic hyperplasia.

CONCLUSION

The extended transsternal thymectomy, along with the postoperative regimen of pyridostigmine and prednisolone was associated with a high rate of clinical improvement among MG patients with thymoma or thymic hyperplasia.

Video-assisted thoracoscopic microthymectomy

There are many techniques for performing video-assisted thoracoscopic (VATS) thymectomy. This article describes one particular technique that we employ in thymectomies as well as lobectomies. The principles of both operations are as follows, and have been presented in greater detail for lobectomies previously: (I) the use of ports no greater than 5-mm in the intercostal spaces; (II) the use of a 12-mm subxiphoid port; (III) subxiphoid removal of the specimen; (IV) carbon dioxide (CO2) insufflation; (V) vision enabled through a 5-mm camera; (VI) in microlobectomies, the use of a 5-mm stapling device. These principles are particularly suited to thymectomy, as there are no large vascular structures that require stapling and a large number of the instruments required for thymectomy are already 5-mm in diameter, including energy devices, graspers, clip applicators and suction devices. We believe that this technique, which eliminates the need for large incisions in the intercostal spaces, is less painful than other techniques that we have employed, including intercostal uniportal surgery. It also allows the use of CO2 insufflation, which is very useful indeed in endoscopic thymectomies. Furthermore, microthymectomy is technically easier than subxiphoid-only techniques, in that it requires little modification compared to a more conventional VATS thymectomy. We describe this technique in detail in this article.

Development of the international thymic malignancy interest group international database: an unprecedented resource for the study of a rare group of tumors

BACKGROUND

Our knowledge of thymic malignancies has largely been derived from small, single-institution series. Recognition of the need for broad collaboration led to the creation of the International Thymic Malignancy Interest Group (ITMIG) and the development of a large, centralized database to advance knowledge of these rare tumors.

METHODS

A multidisciplinary Database Committee was convened to define a common set of data elements a priori. Retrospective data were solicited from ITMIG members and collated using standardized fields. Patients with thymoma, thymic carcinoma, or thymic carcinoid were included.

RESULTS

Over a 6-month period, 47 institutions spanning 15 countries contributed a total of 6097 cases (mean, 129 [range, 10-1209]). The sex distribution was equal for thymomas, but there was a greater proportion of men with thymic carcinoma and thymic carcinoid (p < 0.0001). Nearly all cases (99%) were treated surgically. WHO type B2 was the most frequent histologic classification among thymomas, whereas squamous was the most common among thymic carcinomas. In total, 38% of patients with thymoma had myasthenia gravis compared with less than or equal to 5% for thymic carcinoma and thymic carcinoid. Median overall survival was 18.9 years (95% confidence interval [CI], 17.4-20.3) for thymoma, 6.8 years (95% CI, 5.5-7.9) for thymic carcinoma, and 7.5 years (95% CI, 6.5-8.5) for thymic carcinoid.

CONCLUSIONS

The rapid creation of the ITMIG database demonstrates the feasibility of international collaboration for this rare set of malignancies and attests to the engagement of its membership. This database represents the largest collective data set ever assembled and provides an unprecedented resource for research of these tumors.

Laparoscopic Sleeve Gastrectomy in a Morbidly Obese Patient with Myasthenia Gravis: A Review of the Management

Myasthenia gravis, a disorder of neuromuscular transmission, presents a unique challenge to the perioperative anesthetic management of morbidly obese patients. This report describes the case of a 27-year-old morbidly obese woman with a past medical history significant for myasthenia gravis and fatty liver disease undergoing bariatric surgery. Anesthesia was induced with intravenous agents and maintained with an inhalational and balanced intravenous technique. The nondepolarizing neuromuscular blocker Cisatracurium was chosen so that no reversal agents were given. Neostigmine was not used to antagonize the effects of Cisatracurium. The goal of this approach was to reduce the risk of complications such as postoperative mechanical ventilation. The anesthetic and surgical techniques used resulted in an uneventful hospital course. Therefore, we can minimize perioperative risks and complications by adjusting the anesthetic plan based on the patient's physiology and comorbidities as well as the pharmacology of the drugs.

Olfactory and gustatory dysfunction in Myasthenia gravis: A study in Turkish patients

OBJECTIVE

Myasthenia gravis (MG) is commonly viewed as a muscle disorder. Less is known about neurosensory function and dysfunction in MG. We aim to evaluate olfactory and gustatory behavior in Turkish patients with MG, and compare these results with age and sex-matched healthy controls.

MATERIAL/METHODS

30 individuals with MG, and 30 healthy volunteers were studied. Olfactory function was studied with the Sniffin' sticks test. Taste strip test was used for studying taste function. The t-test was used for analyzing continuous variables, and the chi-square test for categorical data. Clinical staging and medication status were included in a model analyzed using analysis of variances.

RESULTS

MG patients showed significantly lower olfactory (p<0.001) and gustatory scores (p<0.001) than the healthy controls. In addition, olfactory loss correlated with the severity of the disease. Medications for MG did not influence these results.

CONCLUSION

This study replicates the olfactory dysfunction found elsewhere in MG. Further, gustatory dysfunction, an activity unrelated to muscle strength, was also unveiled. Medications used for treating MG must not be blamed for the chemosensory dysfunction found in this neurological disorder.

Induction intravenous cyclophosphamide followed by maintenance oral immunosuppression in refractory myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) can be refractory to conventional immunotherapy. We report on the efficacy and durability of intravenous (IV) remission-induction cyclophosphamide (CYC) followed by oral immunosuppression in refractory MG.

METHODS

We identified 8 patients from our medical records with moderate or severe refractory MG who were treated with 6 cycles of IV CYC (0.75 g/m(2) ) every 4 weeks followed by oral immunosuppression.

RESULTS

Six patients improved within 3 months of treatment. Four patients remained in clinical remission (mean follow-up 31 months). Two patients responded partially, and 1 patient relapsed after 11 months. Two patients were non-responders. CYC was well tolerated. Acetylcholine receptor antibody levels remained below pretreatment levels in patients in clinical remission. The leukocyte nadir was lower in CYC responders.

CONCLUSIONS

Remission-induction IV CYC followed by oral immunosuppression is a rapid, effective, and durable treatment for refractory MG. Adding a post-CYC immunosuppressant may account for low relapse rates compared with other published series.

Disease specific signature of circulating miR-150-5p and miR-21-5p in myasthenia gravis patients

PURPOSE

Reliable biological markers for patients with the autoimmune neuromuscular disorder myasthenia gravis (MG) are lacking. We determined whether levels of the circulating immuno-microRNAs miR-150-5p and miR-21-5p were elevated in sera from clinically heterogeneous MG patients, with and without immunosuppression, as compared to healthy controls and patients with other autoimmune disorders.

METHODS

Sera from 71 MG patients and 55 healthy controls (HC) were analyzed for the expression levels of miR-150-5p and miR-21-5p with qRT-PCR. Sera were also assayed from 23 patients with other autoimmune disorders (AID; psoriasis, Addison's and Crohn's diseases).

RESULTS

34 MG patients had no immunosuppressive drug treatment (MG-0) and 37 patients were under stable immunosuppressive drug treatment since ≥ 6 months (MG+IMM). Serum levels of miR-150-5p and miR-21-5p were higher in the MG-0 patients compared to HC (p<0.0001). Further, miR-150-5p levels were 41% lower and miR-21-5p levels were 25% lower in the MG+IMM compared to MG-0 (p=0.0051 and 0.0419). In the AID patients, mean miR-150-5p and miR-21-5p were comparable with healthy controls (p=0.66).

CONCLUSIONS

The immuno-microRNAs miR-150-5p and miR-21-5p show a disease specific signature, which suggests these microRNAs as possible biological autoimmune markers of MG.

Sialyl Lewis x (CD15s) identifies highly differentiated and most suppressive FOXP3high regulatory T cells in humans

CD4⁺ regulatory T (Treg) cells expressing CD25 and the transcription factor forkhead box P3 (FOXP3) play indispensable roles for immunological self-tolerance and homeostasis. Because human FOXP3⁺CD25⁺CD4⁺ T cells are heterogeneous in function and differentiation status, their analysis and manipulation for treating immunological diseases remains a challenge. Here we show that CD15s (sialyl Lewis x) is specifically expressed by activated, terminally differentiated, and most suppressive FOXP3^high Treg cells, allowing their separation from nonsuppressive FOXP3⁺CD4⁺ T cells secreting inflammatory cytokines. Removal of CD15s⁺CD4⁺ T cells from human blood is indeed sufficient to enhance in vitro antitumor and antiviral antigen responses. CD15s is therefore useful for phenotypic as well as functional analysis of human Treg subpopulations and for targeting them to control immune responses.

CD4⁺ regulatory T (Treg) cells expressing CD25 and the transcription factor forkhead box P3 (FOXP3) are indispensable for immunological self-tolerance and homeostasis. FOXP3⁺CD25⁺CD4⁺ T cells in humans, however, are heterogeneous in function and differentiation status, including suppressive or nonsuppressive cells as well as resting or activated Treg cells. We have searched for cell surface markers specific for suppression-competent Treg cells by using a panel of currently available monoclonal antibodies reactive with human T cells. We found that CD15s (sialyl Lewis x) was highly specific for activated, terminally differentiated, and most suppressive FOXP3^high effector Treg (eTreg) cells and able to differentiate them in various clinical settings from nonsuppressive FOXP3⁺ T cells secreting inflammatory cytokines. For example, CD15s⁺FOXP3⁺ eTreg cells were increased in sarcoidosis, whereas it was nonsuppressive CD15s⁻FOXP3⁺ T cells that were expanded in lupus flares. FOXP3⁺ cells induced from conventional CD4⁺ T cells by T-cell receptor stimulation hardly expressed CD15s. CD15s⁺CD4⁺ T-cell depletion was sufficient to evoke and enhance in vitro immune responses against tumor or viral antigens. Collectively, we have identified CD15s as a biomarker instrumental in both phenotypic and functional analysis of FOXP3⁺CD4⁺ T-cell subpopulations in health and disease. It allows specific targeting of eTreg cells, rather than whole FOXP3⁺CD4⁺ T cells, in controlling immune responses.

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.

Statins and myotoxic effects associated with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies: an observational study in Japan

Statins have a variety of myotoxic effects and can trigger the development of inflammatory myopathies or myasthenia gravis (MG) mediated by immunomodulatory properties. Autoantibodies to 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) have been identified in patients with statin-associated myopathy. The purpose of the present study is to develop an enzyme-linked immunosorbent assay (ELISA) of anti-HMGCR antibodies and to elucidate the clinical significance of anti-HMGCR antibodies in Japanese patients with inflammatory myopathies or MG. We enrolled 75 patients with inflammatory myopathies, who were all negative for anti-signal recognition particle and anti-aminoacyl transfer RNA synthetase antibodies. They were referred to Keio University and National Center of Neurology and Psychiatry between October 2010 and September 2012. We also studied 251 patients with MG who were followed at the MG Clinic at Keio University Hospital. Anti-HMGCR antibodies were detected by ELISA. We investigated demographic, clinical, radiological, and histological findings associated with anti-HMGCR antibodies. We established the anti-HMGCR ELISA with the recombinant protein. Protein immunoprecipitation detected autoantigens corresponding to HMGCR. Immunohistochemistry using muscle biopsy specimens revealed regenerating muscle fibers clearly stained by polyclonal anti-HMGCR antibodies and patients' serum. Anti-HMGCR autoantibodies were specifically detected in 8 patients with necrotizing myopathy. The seropositivity rate in the necrotizing myopathy patients was significantly higher than those in the patients with other histological diagnoses of inflammatory myopathies (31% vs 2%, P = 0.001). Statins were administered in only 3 of the 8 anti-HMGCR-positive patients. Myopathy associated with anti-HMGCR antibodies showed mild limb weakness and favorable response to immunotherapy. All 8 patients exhibited increased signal intensities on short T1 inversion recovery of muscle MRI. Of the 251 patients with MG, 23 were administered statins at the onset of MG. One late-onset MG patient experienced MG worsening after 4-wk treatment with atorvastatin. However, anti-HMGCR antibodies were not detected in the 251 MG patients except for one early-onset MG patient with no history of statin therapy. Anti-HMGCR antibodies are a relevant clinical marker of necrotizing myopathy with or without statin exposure, but they are not associated with the onset or deterioration of MG.

Repeated acetylcholine receptor antibody-concentrations and association to clinical myasthenia gravis development

INTRODUCTION

We aimed to examine the longitudinal association between Myasthenia Gravis (MG) clinical severity and concentration of acetylcholine receptor (AChR)-antibodies to evaluate if AChR-antibody variations correlate to disease severity. A positive AChR-antibody test is specific for MG.

MATERIAL AND METHODS

All patients from western Norway who had two or more AChR- antibody tests in the period 1983-2013 were identified. The Myasthenia Gravis Foundation of America (MGFA) Clinical Classification was used to grade disease development. Multiple ordinal logistic regression analysis was used to estimate a possible predictive effect for AChR-antibody concentration on MGFA classification result.

RESULTS

In 67 patients two or more AChR-antibody tests with a corresponding MGFA-score were performed, with a total of 309 tests. 56 patients were treated with immunosuppressive drugs and 11 by pyridostigmine only. There was a positive association between concentration of AChR-antibodies and longitudinal MGFA-score for the subgroup with immunosuppressive treatment, but not for those treated with pyridostigmine only. This association between AChR-antibody concentration and MGFA score declined with increasing time since onset (p = 0.005 for the interaction of group×time×concentration).

CONCLUSIONS

For MG patients with immunosuppressive treatment, repeated AChR-antibody measurements give information about clinical development, and can therefore be of support in therapeutic decisions.

Intrathymic Tfh/B Cells Interaction Leads to Ectopic GCs Formation and Anti-AChR Antibody Production: Central Role in Triggering MG Occurrence

Myasthenia gravis is a typical acetylcholine receptor (AChR) antibody-mediated autoimmune disease in which thymus frequently presents follicular hyperplasia or thymoma. It is now widely accepted that the thymus is probably the site of AChR autosensitization and autoantibody production. However, the exact mechanism that triggers intrathymic AChR antibody production is still unknown. T follicular helper cells, recently identified responsible for B cell maturation and antibody production in the secondary lymphoid organs, were involved in many autoimmune diseases. Newly studies found T follicular helper (Tfh) cells increased in the peripheral blood of myasthenia gravis (MG). Whether it appears in the thymus of MG and its role in the intrathymic B cells help and autoantibody production is unclear. Therefore, this study aims to determine in more detail whether Tfh/B cell interaction exist in MG thymus and to address its role in the ectopic germinal centers (GCs) formation and AChR antibody production. We observed the frequency of Tfh cells and its associated transcription factor Bcl-6, key cytokine IL-21 enhanced both in the thymocytes and peripheral blood mononuclear cells (PBMCs) of MG patients. In parallel, we also showed increased B cells and autoantibody titers in MG peripheral blood and thymus. Confocal microscope results demonstrated Tfh and B cells co-localized within the ectopic GCs in MG thymus, suggesting putative existence of Tfh/B cells interaction. In vitro studies further showed dynamic behavior of Tfh/B cells interaction and Tfh cells induced autoantibody secretion might through its effector cytokine IL-21. Altogether, our data demonstrated that intrathymic Tfh/B cells interaction played a key role in thymic ectopic GCs formation and anti-AChR antibody production, which might trigger MG occurrence.

8 years' experience with robotic thymectomy for thymomas

BACKGROUND

The accuracy of a three-dimensional robotic-assisted videothoracoscopic approach may favor a radical resection of thymomas. The aim of this study was to demonstrate the feasibility of the robotic approach by reporting 8 years experience in a single referral center of surgical treatment of thymomas.

METHODS

We retrospectively analyzed all consecutive patients who underwent a thymectomy from April 2004 to April 2012. We analyzed the procedure time, morbidity, mortality, conversions, hospitalization, freedom from recurrence, time to progression, and overall survival.

RESULTS

From 2004 until 2012, a total of 138 robotic procedures for mediastinal tumors were performed in our center, of which 37 patients with a mean age of 57.3 years underwent a thymectomy for a thymoma. Histological analysis revealed four type A thymomas (10.8 %), seven type AB thymomas (18.9 %), seven type B1 thymomas (18.9 %), fourteen type B2 thymomas (37.8 %), four type B3 thymomas (10.8 %), and one thymus carcinoma (2.7 %). The Masaoka–Koga stages were as follows: stage I in twenty patients (54 %), stage IIA in five patients (13.5 %), stage IIB in eight patients (21.6 %), stage III in three patients (8.1 %), and stage IVa in one patient (2.7 %). The mean overall procedure time was 149 min (range 88–353). No surgical mortality was reported, and there were no peri-operative complications. No conversions were needed for surgical complications. In three cases, a conversion to sternotomy was preferred by the surgeon because tumor invasion in greater vessels was suspected. Two patients (5.4 %) suffered from a myasthenic crisis postoperatively and required prolonged mechanical ventilation. One patient (2.7 %) underwent a procedure for a thoracic herniation 6 months following thymectomy. The median hospitalization was 3 days. The follow-up analysis showed an overall survival of 100 % and tumor recurrence in one patient (2.7 %).

CONCLUSIONS

Robotic thymectomies are safe in patients with early-stage thymomas. Robotic surgery may also be feasible for some selected advanced thymomas.

Intravenous immunoglobulin as treatment for myasthenia gravis: current evidence and outcomes

We examined the current evidence for the efficacy of IV immunoglobulin (IVIG) in myasthenia gravis (MG) and the outcomes used to demonstrate this efficacy. There is class 1 evidence for the use of short-term IVIG in MG patients worsening MG and also good evidence for IVIG use in myasthenic crisis. For long-term maintenance therapy, controlled studies are lacking and the evidence is limited to class III retrospective studies. The clinical scales, serological, electrophysiological, and patient-reported quality of life outcomes with IVIG have been assessed. At this time, the quantitative myasthenia gravis score, a functional scale, remains the preferable outcome measure as it has demonstrated responsiveness in the clinical trial setting, but a scale incorporating patient-reported outcomes and the patients complaint of fatigue is likely to be preferable. The MG-composite is such a scale, but has measurement limitations that may reduce its sensitivity. Across trials, IVIG has generally been well tolerated.

Experience with the "da Vinci" robotic system for early-stage thymomas: Report of 23 cases

BACKGROUND

The aim of this study was to report a single referral center experience in robotic extended thymectomy for clinical early stage thymomas, evaluating its safety, feasibility and efficacy, with special regard to oncological outcomes.

METHODS

Between January 2009 and December 2012, we retrospectively selected patients who underwent robotic extended thymectomy for clinical early stage thymomas. Operative time, morbidity, mortality, duration of hospitalization, and overall and disease-free survival were analyzed.

RESULTS

There were 23 patients (15 males, eight females) with a mean age of 49.3 years (range 20-66). There were no intra-operative complications, and no mortality. The mean operative time was 85.2 minutes (range 60-180). No patient underwent conversion to open surgery. All post-operative complications (4.3%) were conservatively treated. The mean post-operative stay was 3.6 days (range two to nine). The pathological analysis revealed Masaoka stage I (21 cases) and II (two cases). No disease recurrence occurred at a mean follow-up of 24.8 months.

CONCLUSIONS

Robotic thymectomy is a safe and feasible technique, with a short operative time and low morbidity. Even on a small series with short follow-up, robotic extended thymectomy for thymoma appeared to be an effective treatment for early-stage thymomas.

Thymectomy by video-assisted thoracoscopy versus open surgical techniques

Objective

This study was conducted to compare operative variables and postoperative outcomes in adult patients with myasthenia gravis undergoing thymectomy through 3 different operative techniques: total median sternotomy, partial median sternotomy, and video-assisted thoracoscopy.

Methods

30 patients aged 20–65 years were included in this study. They were subdivided into: group A: 8 patients undergoing thymectomy through a total median sternotomy; group B: 9 patients undergoing thymectomy through a partial median sternotomy; and group C: 13 patients undergoing thymectomy through video-assisted thoracoscopy. Preoperative, intraoperative, and postoperative variables, and mortality were compared among groups.

Results

Preoperative variables were well matched in all groups. Operative time was significantly longer in group C. There was no intraoperative complication in any group. Postoperative length of hospital stay was significantly shorter in group C. Postoperative complications occurred in 3 (10%) patients, mostly in groups A and B. There was no perioperative mortality in any group.

Conclusions

Video-assisted thymectomy is as effective as the traditional open surgical approaches for thymectomy in the management of patients with myasthenia gravis. In addition, the improved cosmesis of the video-assisted approach ideally should lead to earlier thymectomy in patients with myasthenia gravis.

Prospects for a T-cell receptor vaccination against myasthenia gravis

T-cell receptor (TCR) vaccination has been proposed as a specific therapy against autoimmune diseases. It is already used in clinical trials, which are supported by pharmaceutical companies for the treatment of multiple sclerosis, rheumatoid arthritis and psoriasis. Current vaccine developments are focusing on enhancement of immunogenicity as well as selecting the best route of immunization and adjuvant to favor the therapeutic effect. In the meantime, academic laboratories are tackling the regulatory mechanisms involved in the beneficial effect of the vaccines to further understand how to control the therapeutic tool. Indeed, several examples in experimental models of autoimmune diseases indicate that any specific therapy may rely on a delicate balance between the pathogenic and regulatory mechanisms. This review presents a critical analysis of the potential of such therapy in myasthenia gravis, a prototype antibody-mediated disease. Indeed, a specific pathogenic T-cell target population and a TCR-specific regulatory mechanism mediated by anti-TCR antibodies and involved in protection from the disease have recently been identified in a patient subgroup. The presence of spontaneous anti-TCR antibodies directed against the pathogenic T-cells that may be boosted by a TCR vaccine provides a rationale for such therapy in myasthenia gravis. The development of this vaccine may well benefit from experience gained in the other autoimmune diseases in which clinical trials are ongoing.