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

Effects of balance strategy training in myasthenia gravis: a case study series

INTRODUCTION

Studies of exercise in patients with myasthenia gravis (MG) are sparse. Balance strategy training (BST) multimodal exercise has proven efficacy in adults for enhancing balance and functional mobility. This prospective study aims to determine if BST improves functional ability and balance in people with MG.

METHODS

Seven individuals with MG participated in a 16-session workstation intervention. Repeated measures (pre/post-intervention and 4-week follow-up) consisting of quantitative myasthenia gravis score (QMG), 6-minute walk test (6MWT), timed up and go (TUG) with dual task (TUG(manual) and TUG(cognitive)), and standing stability on foam with eyes closed (foamEC) were assessed.

RESULTS

Most measurements showed sustained improvement at follow-up. QMG, TUG(cognitive), and foam EC achieved clinically significant improvements (>15%). No adverse effects were reported.

CONCLUSIONS

BST was effective in improving balance and QMG scores in subjects with MG. A multimodal BST approach is thus suggested to target different aspects of balance and functional mobility.

Efficacy of perioperative high-dose prednisolone therapy during thymectomy in myasthenia gravis patients

BACKGROUND

This study aimed to investigate the benefits of administering perioperative high-dose prednisolone in conjunction with thymectomy in patients with myasthenia gravis.

METHODS

We retrospectively reviewed data from patients with Myasthenia Gravis Foundation of America Clinical Class I to IIIB who had undergone an extended thymectomy between 1992 and 2009. Perioperative high-dose prednisolone was administered at starting doses of 10 to 20 mg and escalated up to 100 mg on alternate days. The treatment group comprised 70 patients receiving perioperative high-dose prednisolone, whereas the control group included 61 patients not treated with preoperative steroids. The two groups were compared with respect to baseline clinical characteristics, incidence of postoperative complications, and follow-up disease status.

RESULTS

Prednisolone-treated patients presented with more advanced disease compared to controls (Class IIB or greater, 42 [60.0%] versus 7 [11.3%], respectively; P < 0.001). Mean preoperative%FVC was lower and FEV1.0% was higher in treated patients than in controls (%FVC: 92.4 ± 2.3% versus 99.5 ± 2.4%, respectively; P = 0.037, FEV1.0%: 85.2 ± 1.3% versus 81.4 ± 0.9%, respectively; P = 0.017). The groups were similar in other variables including presence of thymoma, and operative procedure. In the treatment group, disease status was significantly improved only by the induction of high-dose prednisolone before the surgery (P < 0.001), and these patients discontinued anti-cholinesterase therapy more frequently than controls (P < 0.001). Moreover, the treatment group demonstrated markedly lower rates of postoperative crisis (12.2% versus 2.9%, respectively; P = 0.045). The incidence of infection, wound dehiscence, and diabetes mellitus were comparable between groups. Survival analysis demonstrated higher rates of treated patients with improved disease status at three and five years (92% and 96%, respectively) compared to controls (57% and 76%, respectively; P < 0.001). Likewise, significantly greater proportions of treated patients achieved complete stable remission or pharmacologic remission at three, five, and ten years (23%, 42%, and 72%, respectively) compared to controls (10%, 20%, and 44%, respectively; P = 0.002).

CONCLUSIONS

Perioperative high-dose prednisolone therapy is a safe, promising strategy for managing patients with myasthenia gravis and may reduce the incidence of postoperative crisis while improving disease status.

A randomized, double-blind, placebo-controlled phase II study of eculizumab in patients with refractory generalized myasthenia gravis

INTRODUCTION

Complement activation at the neuromuscular junction is a primary cause of acetylcholine receptor loss and failure of neuromuscular transmission in myasthenia gravis (MG). Eculizumab, a humanized monoclonal antibody, blocks the formation of terminal complement complex by specifically preventing the enzymatic cleavage of complement 5 (C5).

METHODS

This study was a randomized, double-blind, placebo-controlled, crossover trial involving 14 patients with severe, refractory generalized MG (gMG).

RESULTS

Six of 7 patients treated with eculizumab for 16 weeks (86%) achieved the primary endpoint of a 3-point reduction in the quantitative myasthenia gravis (QMG) score. Examining both treatment periods, the overall change in mean QMG total score was significantly different between eculizumab and placebo (P = 0.0144). After assessing data obtained from all visits, the overall change in mean QMG total score from baseline was found to be significantly different between eculizumab and placebo (P < 0.0001). Eculizumab was well tolerated.

CONCLUSION

The data suggest that eculizumab may have a role in treating severe, refractory MG.

Expression of immune molecules CD25 and CXCL13 correlated with clinical severity of myasthenia gravis

Differential expressions of immune molecules have been shown in the thymi with pathological results, including myasthenia gravis (MG). CD25 is an activation marker expressed on T cells. CXCL13 mediates the homing and motility of B cells in secondary lymphoid tissues. Herein, we investigated the expressions of CD25 and CXCL13 in the thymi of thymic hyperplasia patients with MG or with non-MG. A total of 34 thymic hyperplasia patients with MG (20 generalized MG (GMG) and 14 ocular MG (OMG) and six thymic hyperplasia patients without MG were enrolled and analyzed using immunohistochemical staining and real-time polymerase chain reaction for CD25 and CXCL13. Our study demonstrated a higher expression of both CD25 and CXCL13 in hyperplastic thymi with OMG or GMG compared to those with non-MG. According to the immunohistochemical results, we observed that CD25 expression was significantly lower in atrophic thymi and non-MG hyperplastic thymi, compared with that in infant thymi (P = 0.002 and 0.005, respectively). In contrast to CD25 expression, we did not observe differential expression of CXCL13 among three control groups. And a similar CD25 mRNA expression was found in real-time polymerase chain reaction (PCR) results. We observed that both hyperplastic thymi with OMG or GMG expressed significantly higher levels of CD25 than those with non-MG (P = 0.007 and 0.001, respectively). And an increase of CD25 expression was observed in hyperplastic thymi with GMG compared to those with OMG (P = 0.030). Similarly, CXCL13 expression was significantly higher in hyperplastic thymi with GMG or with OMG than those with non-MG (P = 0.001 and 0.050, respectively). No significant CXCL13 expression difference was found between hyperplastic thymi with GMG and those with OMG (P > 0.05). The real-time PCR results showed a similar tendency of CD25 mRNA expression among the thymi of non-MG, OMG, and GMG patients, but the difference did not reach significance (P > 0.05). An obvious increased expression of CXCL13 was found in hyperplastic thymi with GMG patients, compared to those with non-MG and OMG patients (P = 0.003 and 0.071, respectively). There was no difference found between hyperplastic thymi with non-MG and with OMG. Regression analysis showed a positive correlation between thymic CD25 level and MG symptom severity (F = 28.240; P = 0.000, r = 0.523). Similarly, a positive correlation was found between thymic CXCL13 expression and MG disease severity (F = 36.093; P = 0.000, r = 0.671). Taken together, our findings suggest CD25 and CXCL13 participate in the pathogenesis of MG and may influence the clinical symptoms of MG.

Fracture rate in patients with myasthenia gravis: the general practice research database

SUMMARY

The aim of this study was to evaluate fracture risk after onset of myasthenia gravis using the UK General Practice Research Database. Overall fracture risk is not statistically increased compared with age- and gender-matched controls irrespective of glucocorticoid use, but was increased in those using antidepressants, anxiolytics or anticonvulsants.

INTRODUCTION

Myasthenia gravis (MG) is a neuromuscular disease which has been associated with an increased falls risk and glucocorticoid-induced osteoporosis, recognized determinants of increased fracture risk. The aim of this study was to evaluate the risk of fracture after onset of MG.

METHODS

We conducted a retrospective cohort study using the UK General Practice Research Database (1987-2009). Each MG patient was matched by age, sex, calendar time and practice to up to six patients without a history of MG and we identified all fractures and those associated with osteoporosis.

RESULTS

Compared to the control cohort, there was no statistically significant increased risk observed in patients with MG for any fracture (adjusted hazard ratio [AHR] 1.11; 95 % confidence interval [CI], 0.84-1.47) or osteoporotic fractures (AHR 0.98 [95 % CI 0.67-1.41]). Further, use of oral glucocorticoids up to a cumulative dose exceeding 5 g prednisolone equivalents did not increase risk of osteoporotic fracture (AHR 0.99 [95 % CI, 0.31-3.14]) compared with MG patients without glucocorticoid exposure. However, fracture risk was higher in patients with MG prescribed antidepressants (AHR 3.27 [95 % CI, 1.63-6.55]), anxiolytics (AHR 2.18 [95 % CI, 1.04-4.57]) and anticonvulsants (AHR 6.88 [95 % CI, 2.91-16.27]).

CONCLUSION

Overall risk of fracture in patients with MG is not statistically increased compared with age- and gender-matched controls irrespective of glucocorticoid use but was increased in those using antidepressants, anxiolytics or anticonvulsants. These findings have implications in strategies preserving bone health in patients with MG.

Unilateral extended thoracoscopic thymectomy for nontumoral myasthenia gravis--a new standard

Myasthenia gravis (MG) is a heterogeneous disorder with a fluctuating, clinical, pathologic, and immunobiological picture. Today, it is believed that effective treatment of MG must include both immunosuppression and surgery. Thymectomy is recommended by neurologists for patients with nontumoral MG as an option to increase the probability of remission or improvement. Currently, thoracoscopic thymectomy is considered a good alternative to the standard open approach because of its higher rate of acceptance, low morbidity, and high efficacy, as measured by complete stable remission rates. We present a review of the experience of unilateral extended thoracoscopic thymectomy for nontumoral MG, a technique that could became a new standard in the complex management of MG treatment.

Clinical outcome of juvenile myasthenia gravis after extended transsternal thymectomy in a chinese cohort

BACKGROUND

The role of surgical treatment for juvenile myasthenia gravis (MG) remains unclear. Here, we performed a retrospective study to evaluate the predictors of clinical outcome of juvenile MG treated with extended transsternal thymectomy.

METHODS

A total of 141 consecutive juvenile MG patients underwent extended transsternal thymectomy at an academic hospital over a 20-year period were reviewed. Thymectomy was performed in patients resistant to pyridostigmine therapy, with generalized symptoms or ocular MG with partial response to pyridostigmine for more than 2 years. Variables potentially affecting responses to extended transsternal thymectomy were evaluated using Kaplan-Meier analysis and Cox regression modeling. Complete stable remission (CSR) is defined as asymptomatic without medication for more than 12 months.

RESULTS

There were 96 patients with ocular MG and 45 generalized MG, the median age at disease onset was 6 years and that at operation was 12 years. Among 135 patients with complete postoperative follow-up, 34 (25.2%) achieved CSR, 28 (20.7%) experienced pharmacologic remission, 61 (45.2%) improved, 5 (3.7%) remained stable, and 7 (5.2%) deteriorated. The results indicated the disease-onset age greater than 6 years and age at operation greater than 12 years were both positively associated with CSR responses. Postoperative steroid treatments in ocular MG and preoperative disease duration in generalized MG (>12 months) were negatively associated with CSR responses.

CONCLUSIONS

Extended transsternal thymectomy for Chinese juvenile MG patients has an efficacy comparable with reports from other ethnicities. Juvenile patients with disease-onset age greater than 6 years, age at operation greater than 12 years, and shorter disease duration of generalized MG are associated with favorable clinical outcomes.

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.

Phase II trial of methotrexate in myasthenia gravis

Prednisone is a frequently used treatment for myasthenia gravis (MG) but it has numerous side effects. Methotrexate is a selective inhibitor of dihydrofolate reductase and lymphocyte proliferation and is an effective immuosuppressive medication for autoimmune diseases. Given the negative results of the mycophenolate mofetil study, search for an effective immunosuppressant drug therapy is ongoing. The objective is to determine if oral methotrexate is safe and effective for MG patients who take prednisone. We have initiated a randomized, double-blind, placebo-controlled multicenter trial of methotrexate versus placebo in patients taking at least 10 mg/day of prednisone at enrollment. The methotrexate dose is increased to 20 mg and the prednisone dose is adjusted per protocol during the study. Clinical and laboratory evaluations are performed monthly for 12 months, with the primary efficacy measure being the nine-month prednisone area under the curve (AUC) from months 3 to 12. Secondary outcome measures include MG outcomes, quality of life measures, and a polyglutamation biomarker assay. A total of 18 U.S. sites and 2 Canadian sites are participating, with 48 screened cases, 42 enrolled, with 19 still active in the study.

Evaluation of the New Classification and Surgical Strategy for Myasthenia Gravis

The aim of this study was to discuss the new methods of clinical classification and staging of patients with myasthenia gravis (MG) proposed by our group and to summarize the experiences of surgical treatment of MG with a novel incision by cutting the sternum cross-sectionally at the second intercostal level. A retrospective analysis was made for the clinical data from the patients with MG who underwent thymectomy from July 1988 to May 2009. The surgical procedures were designed into three groups, a group with Osserman classification and median incision of the sternum (Group 1), a group with MGFA typing (Myasthenia Gravis Foundation of America) and a small transverse sternal incision at the second intercostal level (Group 2), and a group with new typing and a smaller transverse sternal incision at the second intercostal level (Group 3). Observation of the clinical typing and staging was made in the patients with myasthenia crisis. The parameters such as procedure duration in Group 2 and 3 was significantly lower than those in Group 1 ( P < 0.05). The incidence of myasthenia crisis in Group 3 was significantly lower than that in Groups 2 and 3 ( P < 0.05). The procedure with a smaller transverse sternal incision at the second intercostal level (Group 3) is a safer method for patients with MG. The combination of this procedure with the new typing and staging methods proposed by our group could facilitate the selection of operation indications and opportunity, resulting in the lower incidence of myasthenia crisis and mortality. Our new procedure is well deserved to be a preferential selection by other hospitals.

Myasthenia gravis: a review

Acquired myasthenia gravis is a relatively uncommon disorder, with prevalence rates that have increased to about 20 per 100,000 in the US population. This autoimmune disease is characterized by muscle weakness that fluctuates, worsening with exertion, and improving with rest. In about two-thirds of the patients, the involvement of extrinsic ocular muscle presents as the initial symptom, usually progressing to involve other bulbar muscles and limb musculature, resulting in generalized myasthenia gravis. Although the cause of the disorder is unknown, the role of circulating antibodies directed against the nicotinic acetylcholine receptor in its pathogenesis is well established. As this disorder is highly treatable, prompt recognition is crucial. During the past decade, significant progress has been made in our understanding of the disease, leading to new treatment modalities and a significant reduction in morbidity and mortality.

Robotic-assisted thymectomy with Da Vinci II versus sternotomy in the surgical treatment of non-thymomatous myasthenia gravis: early results

BACKGROUND

The role of thymectomy in myasthenia gravis remains controversial. The remission rate 5years after surgery varies from 13 to 51% in the literature. Sternotomy is the standard technique, though unacceptable by patients because of significant esthetic sequelae. Our objective was to demonstrate that the robot-assisted technique using the Da Vinci Surgical Robot II is at least as efficient and leaves fewer scars than the standard surgical technique.

METHODS

We retrospectively reviewed the data of 31 consecutive patients suffering from myasthenia gravis who underwent surgery in our center from January 1998 to March 2010. Ten patients with thymoma were excluded from this study. Two groups were formed: group 1 corresponding to patients treated with sternotomy, group 2 patients with robot-assisted technique. The duration of the hospital stay, the pain on D1, the degree of improvement at 1year according to Myasthenia Gravis Foundation of America (MGFA) classification, the frequency of relapses, and perioperative treatment were studied.

RESULTS

Our sample consisted of 14 women and seven men. The mean age was 31.3years. The mean delay before surgery was 24months. Group 1 included 15 patients and group 2 had six patients. The complete remission rate at 1year was 9.5% (n=2). Surgery decreased the frequency of relapses after surgery (P=0.08) equally in the two groups. The duration of hospital stay and the pain level on D1 in group 2 were significantly lower than those in group 1 (P=0.02 and P<0.001). The degree of postoperative improvement was not significantly different between the two groups (P=0.31).

CONCLUSION

The results at 1year are fully comparable for sternotomy and the robot-assisted technique. The robot provides additional benefits of minimally invasive techniques: minimal esthetic sequelae in often young patients, less parietal morbidity (including pain), shorter hospital stays. Our complete remission rate, lower than those in the literature, must be considered taking into account the early nature of these results. The surgical robot, because of its many advantages, appears to be a promising technique and should facilitate the early management of these patients.

Thymectomy for thymoma and myasthenia gravis. A survey of current surgical practice in thymic disease amongst EACTS members

Thymic disorders, both oncological and non-oncological, are rare. Multi-institutional, randomized studies are currently not available. The Thymic Working Group of the European Association for Cardio-Thoracic Surgery (EACTS) decided to perform a survey aiming to estimate the extent and type of current surgical practice in thymic diseases. A questionnaire was addressed to the thoracic and cardio-thoracic members of the society, and the answers received from 114 participants were analysed. High-volume surgeons cooperate more frequently with a dedicated neurologist and anaesthesist (P = 0.04), determine more frequently neurological scores pre- and postoperatively (P = 0.02) and do not operate on thymic hyperplasia in stage I myasthenia gravis (MG) (P = 0.04). High-volume thymoma surgeons more often use a transpleural approach for stage I thymoma < 4 cm (P = 0.01), induction therapy (P = 0.05) and are more likely to have access to a tissue bank (P = 0.04). Both in thymoma and MG surgery, cooperative prospective studies seem to be feasible in dedicated thoracic surgical associations as EACTS.

Evaluation of a scale of patient-reported outcomes for the assessment of myasthenia gravis patients in China

OBJECTIVE

To evaluate a scale of patient-reported outcomes for the assessment of myasthenia gravis patients (MG-PRO) in China.

METHODS

A total of 100 MG patients were interviewed for the field testing. Another 56 MG patients were selected and assessed with the MG-PRO scale before treatment and at 1, 2 and 4 weeks after treatment. The classical test theory and item response theory (IRT) were used to assess the psychometric characteristics of the MG-PRO scale.

RESULTS

The MG-PRO scale included 4 dimensions: physical, psychological, social environment, and treatment. Confirmatory factor analysis showed that each dimension was consistent with the theoretical construct. The scores of the physical and psychological dimensions increased significantly at 1 week after treatment (P<0.05). All the dimension scores and the MG-PRO score increased significantly at 2 and 4 weeks after treatment (P<0.05). IRT showed that person separation indices were greater than 0.8, most of the item fit residual statistics were within ± 2.5, and no item had uniform or non-uniform differential item functioning (DIF) between gender and age (<40, [Symbol: see text]40).

CONCLUSIONS

The MG-PRO scale is valid for measuring the quality of life (QOL) of MG patients, with good reliability, validity, responsiveness, and good psychometric characteristics from IRT. It can be applied to evaluate the QOL of MG patients and to assess treatment effects in clinical trials.

Myasthenia gravis in Jamaican children: a 12-year institutional review

BACKGROUND

Myasthenia gravis is uncommon in children. The clinical characteristics in children of the English-speaking Caribbean have not been documented previously.

OBJECTIVE

To describe the clinical characteristics and outcome of children with myasthenia gravis at two tertiary hospitals in Jamaica.

METHODS

The case-notes of all children with a diagnosis of myasthenia gravis managed at the University Hospital of the West Indies and Bustamante Hospital for Children between January 1994 and December 2005 were reviewed.

RESULTS

There were 34 children; mean age of onset of illness was 7.5 years and mean period of follow-up was 38.5 months. The male-to-female ratio was 1:1.3. Nineteen (59%) presented with ocular manifestations; 47% of these developed signs of generalised involvement. Most were treated with pyridostigmine and prednisone. Eight patients had thymectomy. Four patients (12%) entered remission. There were two deaths.

CONCLUSIONS

Myasthenia gravis in Jamaican children is similar to that in other populations. It is more common in female children. Most children present with ocular manifestations and remission occurs infrequently.

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

OBJECTIVE

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

BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Long-term respiratory muscle endurance training in patients with myasthenia gravis: first results after four months of training

Myasthenia gravis (MG) is characterized by reduced muscle endurance and is often accompanied by respiratory complications. Improvement of respiratory function is therefore an important objective in MG therapy. A previous study demonstrated that respiratory muscle endurance training (RMET) over four weeks increased respiratory muscle endurance of MG patients to about 200% of baseline. The purpose of the present study was to establish an appropriate maintenance training and to test its effects over four months. Ten patients with mild to moderate MG participated in this study. During the first month, they performed five training sessions per week. For the following 3 months, training frequency was reduced to five sessions per two weeks. Myasthenia score, lung function, and respiratory endurance were determined prior to training, after the first month, and after 4 months. Myasthenia score improved from 0.71 ± 0.1 to 0.56 ± 0.1 (P = 0.007). Respiratory endurance time increased from 6.1 ± 0.8 to 20.3 ± 3.0 min (P < 0.001). In conclusion, this RMET maintenance program is feasible and is significantly beneficial for MG patients.

Comparison of IVIg and PLEX in patients with myasthenia gravis

OBJECTIVE

Both IV immunoglobulin (IVIg) and plasma exchange (PLEX) are immunomodulatory treatments used to treat patients with myasthenia gravis (MG), but the choice of which treatment to administer to patients is limited due to lack of evidence from adequately powered, masked, randomized, standardized trials.

METHODS

We randomized 84 patients with moderate to severe MG defined as a Quantitative Myasthenia Gravis Score for disease severity (QMGS) of >10.5 and worsening weakness to IVIg (Gamunex®, Talecris Biotherapeutics) 1 g/kg/day for 2 consecutive days or PLEX (Caridian Spectra) 1.0 plasma volume exchanges for 5 exchanges. The patients were evaluated at day 14 after treatment for the primary efficacy parameter of change in QMGS and secondary clinical and electrophysiologic parameters and were followed for a total of 60 days.

RESULTS

Both IVIg and PLEX reduced the QMGS, and IVIg was comparable to PLEX in efficacy. The dropout rate was the same for both treatment arms and both treatments were well-tolerated. The presence of acetylcholine receptor antibodies and greater baseline disease severity predicted a better response to therapy. The postintervention status revealed that the same proportion of patients improved with treatment: 69% on IVIg and 65% on PLEX. The duration of improvement was similar with both treatments.

CONCLUSIONS

IVIg has comparable efficacy to PLEX in the treatment of patients with moderate to severe MG. Both treatments are well-tolerated, and the duration of effect is comparable. Either treatment may be offered to patients depending on availability of resources.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that IVIg and PLEX have comparable efficacy and are equally tolerated in adult patients with moderate to severe MG within 2 weeks of treatment.

Repetitive nerve stimulation of facial and hypothenar muscles: relative sensitivity in different myasthenia gravis subgroups

AIM

To assess the utility of repetitive nerve stimulation (RNS) in facial and hypothenar muscles in the clinical groups of myasthenia gravis (MG).

PATIENTS AND METHODS

We performed RNS study in the orbicularis oculi (O.O.), nasalis and abductor digiti quinti (ADQ) in 115 consecutive myasthenic patients and classified them according to the classifications of the Myasthenia Gravis Foundation of America. Patients were classified into three groups: group 1, group 2 (IIa, IIIa and IVa) and group 3 (IIb, IIIb and IVb).

RESULTS

RNS was abnormal in 95 patients (82.6%): 78.3% in the O.O., 66.1% in the nasalis and 19.1% in the ADQ. Both facial muscles were statistically more sensitive than the ADQ in all groups of patients. RNS in the O.O. was more frequently abnormal than in the nasalis only in group 1. Sensitivity to acetylcholine antibodies in myasthenic patients was 84%. Acetylcholine receptor (AChR) and muscle-specific tyrosine kinase antibodies were present in 96.7% of the patients with abnormal RNS in both facial muscles. Single-fiber electromyogram (SFEMG) was abnormal in 91.3% of the tested patients. One of the three tests used for the diagnosis of MG (AChR antibodies, SFEMG, RNS) was abnormal in 99.1% of the patients.

DISCUSSION

O.O. is the most sensitive muscle in all groups of MG followed by nasalis, while the ADQ is the muscle with the lowest sensitivity. Facial muscles, especially the O.O., should be the first to be tested in MG. The negativity of all tests (RNS, AChR antibodies, SFEMG) should question the diagnosis of MG, even in the presence of symptoms consistent with MG.

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.

Management of myasthenic patients with thymoma

Myasthenia gravis (MG) associated with thymomas differs from nonthymomatous MG, and thymomas associated with MG are also different from non-MG thymomas. According to the World Health Organization classification, the incidence of MG in thymomas was the highest in the subtypes B2, B1, and AB. Transsternal approach is still regarded as the gold standard for surgical treatment of thymomas. Less-invasive techniques of thymectomy are promising, but it is too early to estimate their real oncological value. In the series including more than 100 patients, the prognosis for survival is better in patients with thymomas associated with MG than in those with non-MG thymomas, and the prognosis for patients with MG associated with thymoma is worse than that for patients with nonthymomatous MG.

Proton magnetic resonance spectroscopy of the intrinsic tongue muscles in patients with myasthenia gravis with different autoantibodies

OBJECTIVE

To assess lipid composition of the intrinsic tongue muscles in patients with myasthenia gravis (MG).

METHODS

This study included 15 MG patients with antibodies against muscle-specific kinase (MuSK), 15 matched MG patients with antibodies against acetylcholine receptor (AChR) and 15 matched healthy subjects. Middle posterior region of the tongue was analyzed by single voxel point-resolved proton magnetic resonance spectroscopy (MRS) using 1.5T MRI scanner.

RESULTS

MRS obtained from subject with AChR MG showed a broad resonance arising from methylene groups of lipids (PMN) with no observable shoulder attributed to methyl groups (PML). Full-width at half maximum (FWHM) of PMN+PML peak showed higher value in patients with AChR MG in comparison to healthy subjects and MuSK MG patients (p<0.05). In patients with MuSK MG, the shape and FWHM of PMN+PML peak was similar as in healthy subjects (p>0.05), with tendency toward increased ratio between PMN and resonance from vinyl protons of lipids (PV). In both AChR and MuSK MG, total creatine resonance (creatine+phosphocreatine, CP) was almost absent with significant increase of PMN/CP ratio in comparison to healthy subjects (p<0.05).

CONCLUSION

MRS is useful in revealing muscle lipid composition in MG. In patients with AChR MG, MRS showed increased lipid content in the tongue muscles due to the lipid migration from intra- to extramyocellular space. Finding in patients with MuSK MG might reflect intramyocellular lipid deposition in the tongue. CP decrease in tongue muscles indicated impairment of oxidative metabolism in both AChR MG and MuSK MG.

Clinical efficacy and immunological impact of tacrolimus in Chinese patients with generalized myasthenia gravis

In this multicenter, open-label pilot study, the efficacy, safety, and immunological impact of tacrolimus in Chinese patients with generalized myasthenia gravis are assessed. Forty-seven generalized myasthenia gravis (MG) patients were enrolled into this study and given 3mg/day tacrolimus for 24 weeks. The primary efficacy measurements used to monitor response to tacrolimus in MG patients were the Osserman grade, the quantitative MG score (QMGS) recommended by the MGFA, the MG-specific manual muscle testing (MMT) score, and the MG-related activities of daily living (MG-ADL) scale. Also, reduction in steroid doses was used to monitor the effect of tacrolimus. Clinical evaluations were conducted at weeks 4, 8, 12, 16, 20, and 24, while immunological parameters were measured at weeks 4, 12, and 24. Measurements of the Osserman grade, QMGS, MMT, and MG-ADL all suggested improvement in patient health by the fourth week of treatment. Steroid dosage was reduced during the course of the study in 74.2% of the forty-three patients who completed the study. There were thirty-one reported adverse events in the study. Only one was considered serious. We found that tacrolimus reduced levels of the IFN-γ, IL-2, IL-10, and IL-13 cytokines and induced the proliferation of tolerogenic plasmacytoid dendritic cells after treatment. Tacrolimus did not change the population of T cell subtypes but did steadily reduce the population of BAFF-R(+) CD19(+) B cells over the course of the study. Our results show that tacrolimus improves the clinical condition of MG patients and is well tolerated. The decrease in IL-13 and reduction of BAFF-R(+) CD19(+) B cells may be related to the therapeutic effect of tacrolimus.

Rethinking research ethics

Contemporary research ethics policies started with reflection on the atrocities perpetrated upon concentration camp inmates by Nazi doctors. Apparently, as a consequence of that experience, the policies that now guide human subject research focus on the protection of human subjects by making informed consent the centerpiece of regulatory attention. I take the choice of context for policy design, the initial prioritization of informed consent, and several associated conceptual missteps, to have set research ethics off in the wrong direction. The aim of this paper is to sort out these confusions and their implications and to offer instead a straightforward framework for considering the ethical conduct of human subject research. In the course of this discussion I clarify different senses of autonomy that have been confounded and present more intelligible justifications for informed consent. I also take issue with several of the now accepted dogmas that govern research ethics. These include: the primacy of informed consent, the protection of the vulnerable, the substitution of beneficence for research's social purpose, and the introduction of an untenable distinction between innovation and research.

Airway limitation and exercise intolerance in well-regulated myasthenia gravis patients

OBJECTIVES

Myasthenia gravis (MG) is an autoimmune disease of neuromuscular synapses, characterized by muscular weakness and reduced endurance. Remission can be obtained in many patients. However, some of these patients complain of fatigue. The aim of this study was to assess exercise capacity and lung function in well-regulated MG patients.

PATIENTS AND METHODS

Ten otherwise healthy MG patients and 10 matched controls underwent dynamic spirometry, and a ramped symptom-limited bicycle exercise test. Spirometric variables included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximum voluntary ventilation (MVV). Exercise variables included maximal oxygen uptake (VO(2) max), anaerobic threshold (VO(2) AT) maximum work load (W), maximum ventilation (VE max), and limiting symptom.

RESULTS

Myasthenia gravis patients had significantly lower FEV1/FVC ratio than controls. This was more marked in patients on acetylcholine esterase inhibitors. On the contrary, patients not using acetylcholine esterase inhibitors had a significantly lower exercise endurance time.

CONCLUSION

Well-regulated MG patients, especially those using pyridostigmine, tend to have an airway obstruction. The modest airway limitation might be a contributing factor to their fatigue. Patients who are not using acetylcholinesterase inhibitor seem to have diminished exercise endurance in spite of their clinically complete remission.

Extended transcervical thymectomy: the ultimate minimally invasive approach

The ideal operative technique for thymectomy in myasthenia gravis remains controversial. Most surgeons perform thymectomy through median sternotomy; more recently, thoracoscopic and robotic approaches have been described. "Extended transcervical thymectomy" is an out-patient procedure that appears less morbid and costly than other approaches. It allows a complete extracapsular thymic resection. Kaplan-Meier complete stable remission rates after transcervical thymectomy are 33% and 35% at 3 and 6 years (higher including patients remaining on single-drug immunosuppression). The major surgical complication rate is 0.7%. We believe that this less morbid and less costly operation is a very reasonable choice in the surgical treatment of myasthenia gravis.

Video-assisted thoracic surgery thymectomy: the better approach

Minimally invasive video-assisted thoracic surgery (VATS) thymectomy has evolved significantly over the last decade. The most common indication for VATS thymectomy is the treatment of myasthenia gravis (MG). Video-assisted thoracic surgery thymectomy results in less postoperative pain, better preserved pulmonary function, and improved cosmesis, which can be particularly important to many young female MG patients. Results of VATS thymectomy, in terms of complete stable remission from MG and symptomatic improvement, as well as safety, are comparable with conventional surgical techniques. This more patient-friendly approach would lead to wider acceptance by MG patients and their neurologists for earlier thymectomies and improved outcomes.

Extended videothoracoscopic thymectomy in nonthymomatous myasthenia gravis

Myasthenia gravis (MG) is an uncommon, organ-specific, autoimmune chronic neuromuscular disorder involving the production of autoantibodies directed against the nicotinic acetylcholine receptors (anti-AchRab). It is characterized by weakness and rapid fatigability of voluntary muscles. Thymectomy is performed early in the course of the disease and is indicated for adults less than 70 years old. For many years, the clinical efficacy of thymectomy has been questioned and so far, its benefits in nonthymomatous MG have not been firmly established. Furthermore, the precise mechanisms of action of thymectomy are unknown although possible explanations include removal of the source of continued antigen stimulation and of the AchRab-recruiting B-lymphocytes as well as immunomodulation. However, thymectomy remains indicated in patients with MG and is widely applied to increase the probability of improvement or remission. This article presents the evolution of technical and surgical advances achieved within the authors' program of extended endoscopically assisted thymectomy since 1995. The use of video-assisted thoracic surgery and its variants for performing thymectomy in MG patients is now well established and will continue to evolve for further improvement in the results.