Myasthenia gravis: immunological mechanisms and immunotherapy

The effect of immunosuppression or thymectomy on the response to tetanus revaccination in myasthenia gravis

OBJECTIVE

To determine the effect of tetanus toxoid (TT) revaccination on circulating B-, T- and NK-cell compartments in myasthenia gravis (MG) patients.

METHODS

Lymphocyte (sub)populations and differentiation stages were assessed by flow cytometry in 50 TT revaccinated MG patients. TT-specific proliferative responses were explored in PBMC cultures.

RESULTS

In patients treated with azathioprine B- and NK cell numbers were strongly decreased. Lymphocyte (sub)populations remained unaffected upon TT revaccination. t All patients showed a significant TT-induced proliferative response.

CONCLUSION

TT revaccination is effective in MG patients with stable disease irrespective of their thymectomy status and medication and does not alter the composition of the lymphocyte compartment.

[A case of elderly-onset myasthenia gravis mimicking stroke with dysarthria and left upper extremity paresis]

An 80-year-old woman presented with sudden-onset dysarthria and left-side dominant quadriparesis and transferred to our hospital. A neurologic examination revealed slurred speech, prominent left upper extremity weakness and mild weakness of the other extremities. Brain MRI revealed a history of right-side cerebral artery bypass surgery, but no new lesions indicative of stroke. Left upper extremity weakness had improved soon after admission, so a transient ischemic attack was suspected. After admission, the dysarthria fluctuated. The patient's respiratory condition deteriorated several days later and she required ventilation support. Assessment of the cause of the respiratory failure revealed positive muscle-specific kinase (MuSK) antibodies, which suggested myasthenia gravis (MG). The symptoms gradually improved with immunotherapy and we were able to completely withdraw her from the ventilator after a few months. There were some reports that dysphagia and dysarthria present suddenly like stroke without fluctuation of symptoms in elderly-onset MG. It is necessary to note that MG diagnosis may be difficult if elderly patients have multiple comorbidities and unclear diurnal fluctuations.

Risk of incident autoimmune diseases in patients with thymectomy

OBJECTIVES

The data concerning the association between Tx and ADs remain unclear and are scarce. This study was undertaken to investigate whether people with Tx are more likely to develop ADs, compared to those without Tx.

METHODS

Individuals who received Tx between 2002 and 2015 were identified and matched on age and sex with individuals without Tx. We performed multivariate and stratified analysis using the Kaplan-Meier method and Cox proportional hazards models in order to estimate the association between Tx and the risk of developing ADs.

RESULTS

A total of 2550 thymectomized (Txd) patients and 24,664.941 non-Txd comparison subjects were selected from NHIRD. Tx-MG (myasthenia gravis) as compared with general population (nonTx-nonMG), adjusted hazard ratio (aHR) were higher for incident Addison disease (aHR = 10.40, 95% CI 1.01-107), autoimmune hemolytic anemia (aHR = 21.54, 95% CI 2.06-14.8), Hashmoto thyroiditis (aHR = 5.52, 95% CI 1.34-34.7), ankylosing spondylitis (aHR = 2.73, 95% CI 1.09-6.84), rheumatoid arthritis (aHR = 5.25, 95% CI 1.79-15.47), primary Sjogren syndrome (pSS) (aHR = 3.77, 95% CI 1.30-11.0), and systemic lupus erythemtoasus (aHR = 10.40). Tx-nonMG as compared with general population, aHR were higher for incident autoimmune hemolytic anemia (aHR = 25.50), Hashmoto thyroiditis (aHR = 6.75) and systemic lupus erythematosus (SLE) (aHR = 13.38). NonTx-MG as compared with general population, aHR were higher for incident Hashmoto thyroiditis (aHR = 6.57), pSS (aHR = 4.50), SLE (aHR = 17.29), and systemic vasculitis (aHR = 25.86).

INTERPRETATION

In conclusion, based on a retrospective cohort study throughout Taiwan, patients with Tx have a higher risk of new onset ADs than patients without Tx.

Long-Term Safety and Efficacy of Tacrolimus in Myasthenia Gravis

PURPOSE

Myasthenia gravis (MG) is a lifelong autoimmune disorder that affects neuromuscular transmission. The long-term treatment plan should include immunotherapy. We investigated the long-term safety and efficacy of tacrolimus for the treatment of MG in real-world clinical practice.

MATERIALS AND METHODS

We retrospectively reviewed 160 MG patients treated with tacrolimus from 2005 to 2015. Myasthenia Gravis Foundation of America (MGFA) clinical classification, MGFA post-intervention status, myasthenic functional score, and dose of oral prednisolone were investigated.

RESULTS

Adverse events occurred in 68 patients (42.5%), most of which were minor and well-managed. Clinical severity scales improved after administration of tacrolimus, compared to the baseline. Compared to 6 months before administration of tacrolimus, prednisolone dose significantly decreased at 12 months after treatment (2.85±0.92 mg/day, p=0.002), 18 months after treatment (3.36±0.99 mg/day, p=0.001), and 24 months after treatment (3.71±0.93 mg/day, p<0.001).

CONCLUSION

Tacrolimus may be effective in reducing the severity of MG and may permit a reduction in the steroid dose prescribed to the patients. Adverse events due to tacrolimus treatment were not serious.

Mycophenolate Mofetil Treatment of Myasthenia Gravis

Objective:

To review published literature evaluating the effectiveness of mycophenolate mofetil for the treatment of myasthenia gravis (MG).

Data Sources:

Searches of MEDLINE (1966–August 2005) and Cochrane Database (1993–August 2005) were conducted. Studies conducted in humans and published in English were retrieved. Additional data were identified through subsequent bibliographic reviews.

Data Synthesis:

Interruption of T- and B-lymphocyte proliferation in various autoimmune diseases has been investigated. Mycophenolate is known to inhibit lymphocyte proliferation and has shown improved clinical responses in several autoimmune diseases including lupus erythematosus, rheumatoid arthritis, and systemic vasculitis. Data suggesting similar benefits in MG treatment have been reported in case reports, retrospective analyses, an open-label trial, and a randomized, double-blind trial.

Conclusions:

Limited evidence from retrospective analyses and clinical trials suggests that mycophenolate is a possible treatment option for patients with MG. Improvement in clinical symptoms and a steroid-sparing effect have been reported when mycophenolate is used in this patient population. Larger, randomized, controlled, and comparative trials are needed to establish optimal dose, time to effect, specific therapeutic role, and long-term safety for mycophenolate when used for treating MG.

Characterization of patients with ocular myasthenia gravis - A case series

Ocular myasthenia gravis (OMG) is sometimes difficult to diagnose and is probably both under-diagnosed and misdiagnosed. We studied the epidemiological parameters, relevant serology, electromyographic (EMG) findings, and the relationship between OMG and thymoma, thymus hyperplasia and other autoimmune disorders compared to generalized MG (GMG) in a case control study of 133 patients with MG (32 patients with OMG and 101 patients with GMG). The proportion of OMG among all MG patients was relatively high (24.1%). It affected more males than females and its onset was at an older age. Although anti-AChR Ab was detected in fewer OMG patients compared to GMG patients, the rate of positive serology in OMG patients was higher than previously reported. Male OMG patients had a higher positive serology rate than female OMG patients. OMG patients tended to have less supportive EMG evidence of neuromuscular disorder. Female OMG patients had higher rates of thymus hyperplasia and higher rates of other autoimmune disorders than males. Diagnosing MG in patients with solitary ocular manifestation may be difficult due to lower rates of paraclinic supportive tests. Awareness of the characteristics of OMG is important in order to avoid delayed or misdiagnosis of MG and to prevent avoidable iatrogenic complications.

The Epidemiology of Myasthenia Gravis in Korea

PURPOSE

An epidemiological study of myasthenia gravis (MG) has not been performed in Korea. The purpose of this study was to estimate the prevalence and incidence of MG in Korea.

MATERIALS AND METHODS

Health Insurance Review and Assessment (HIRA) data from 2010 to 2014 were searched for MG codes as defined by the International Classification of Diseases, 10th revision. After identifying MG cases, we estimated the prevalence and annual incidence of MG based on the HIRA database and Korean population data.

RESULTS

During the study period, 10138 MG cases were identified. The prevalence of MG was 10.42 cases per 100000 people in 2010 and this increased every year to 12.99 cases per 100000 people in 2014. The average incidence of MG between 2011 and 2014 was 0.69 cases per 100000 person-years. The prevalence and incidence were higher in the older (≥ 50 years) age group than in the younger (<50 years) age group [prevalence: 9.26 vs. 19.24 per 100000, relative risk 2.077, 95% confidence interval (CI) 1.976-2.183, p<0.001; incidence: 0.47 vs. 1.18 per 100000, relative risk 2.490, 95% CI 2.006-3.091, p<0.001].

CONCLUSION

This study was the first nationwide population-based epidemiological study of MG in Korea. The prevalence and incidence of MG were consistent with those of previous studies. We found an increase in the prevalence of MG and a predominance of elderly MG patients.

Clinical features of patients with Myasthenia gravis from the Henan province, China

INTRODUCTION

Myasthenia gravis (MG) occurs globally, and many studies have indicated that there are regional differences in epidemiology, biomarkers, and prognosis of MG.

METHODS

A total of 478 patients with MG who visited hospitals in the Henan Province between January 2010 and February 2014 were included. Age, gender, age at onset, serum antibody, thymus pathology, treatment information, and Myasthenia Gravis Foundation of America (MGFA) classification were assessed.

RESULTS

Compared with previous reports from other areas, we found some differences in MG patients from Henan. The proportion of childhood MG in our study was lower than other reports of Oriental patients with MG. There seems to be an association between onset age, muscle involvement, and acetylcholine receptor antibody levels. Thymectomy improved the symptoms in 78.5% of thymectomy-treated patients.

CONCLUSIONS

These differences are likely related to geographical, environmental, and ethnic differences. Understanding these differences will help us to define more specific treatment.

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

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

FK506 attenuates thymic output in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an antibody-mediated, T-cell-dependent autoimmune disease. The symptoms are caused by high-affinity IgG against the muscle acetylcholine receptor (AChR) at the neuromuscular junction. The production of these antibodies in B-cells depends on AChR-specific CD4(+) T-cells and the thymus gland seems to play a significant role in the pathogenesis of MG. Altered thymic T-cell export seems to be associated with a pathological mechanism in myasthenia gravis. Tacrolimus (FK506) has recently been used to treat MG.

MATERIAL AND METHODS

We examined the effects of tacrolimus on thymic T-cell export in patients with MG. Sixteen patients with nonthymomatous and/or thymectomized MG were treated with oral administrations of tacrolimus. To assess the effect of tacrolimus on the thymic output, we assayed the levels of T-cell receptor excision circle (TREC), a molecular marker of thymus emigrants.

RESULTS

T-cell receptor excision circle was not significantly different from those in age-matched controls before tacrolimus therapy, but they were partially decreased 4 months after tacrolimus therapy. T-cell receptor excision circle levels were significantly decreased in the thymomatous group (p < 0.05), but not in the nonthymomatous group. Tacrolimus treatment significantly attenuated TREC levels in cultured CD4(-)CD8(+) cells (p < 0.05), but total cell counts were not significantly changed.

CONCLUSIONS

These results indicate that TREC levels may become a marker of the curative effect of tacrolimus therapy for thymomatous MG, and that tacrolimus suppresses not only activating T-lymphocytes, but also naïve T-cells.

Preoperative high-dose steroid has long-term beneficial effects for myasthenia gravis

Previous studies addressing preoperative steroid treatment have revealed that control of myasthenia gravis (MG) with steroids prior to surgery appeared to stabilize postoperative status. The purpose of our study was to clarify the clinical benefits of the preoperative programmed high-dose steroid treatment on the long-term outcomes of MG patients. We retrospectively reviewed the records of 171 MG patients who were followed up after undergoing thymectomy in our hospital between 1988 and 2006. One hundred and thirteen patients in the programmed treatment group had received preoperative steroid treatment, while 58 patients received no steroid treatment during the preoperative period. Clinical remission, which was defined as the achievement of the modified pharmacologic remission (PR) for at least 1 year, and clinical benefits were compared between the two groups. With regard to the remission after thymectomy, Kaplan-Meier life-table curves for patients in the preoperative steroid treatment group versus those for patients in the no steroid preoperative treatment group revealed a significantly higher probability of the PR in the preoperative steroid treatment group (log-rank test, P < 0.01). This study might be the first, as per our knowledge, to indicate that preoperative programmed high-dose steroid treatment has long-term beneficial effects for MG patients.

Diagnosis and treatment of myasthenia gravis

OBJECTIVE

To describe the clinical presentation, diagnosis, and treatment of myasthenia gravis (MG) while emphasizing the important role of the pharmacist.

DATA SOURCES

English-language articles from MEDLINE pertinent to MG study selection and data extraction: All relevant publications addressing MG management were considered, including prospective comparative trials, epidemiological studies, guideline statements, review articles, and editorials. Particular focus occurred on primary literature published after 1976, but limited amount(s) existed. The American Autoimmune Related Diseases Association, Autoimmune Information Network, Inc., Myasthenia Gravis Foundation of America, Inc. (MGFA), National Institute of Neurological Disorders and Stroke, and National Organization for Rare Disorders.

DATA SYNTHESIS

MG is an autoimmune disorder involving the neuromuscular junction causing characteristic weakness in voluntary muscle groups. To determine appropriate pharmacotherapy, one must characterize the disease based on the degree of function and region of muscles affected. MGFA established a classification system of the disease in order to assess severity. Contemporary treatments include cholinesterase inhibitors, corticosteroids, immodulating/immunosuppressive therapy, intravenous immune globulin, plasmapheresis, and thymectomy. Because of the lack of double-blind, placebo-controlled, randomized clinical trials, treatments are less evidence-based than many other disease states. Clinicians should be aware of the different treatments and recognize the best treatment for the individual.

CONCLUSIONS

The diagnosis and treatment of MG is a therapeutic challenge. Pharmacists play an essential role in the care of these patients by avoiding drugs that exacerbate the disease, promoting optimal pharmacotherapy, monitoring pharmacotherapy, and ensuring compliance with prescribed medications.

Myasthenic crisis: guidelines for prevention and treatment

Management of myasthenic crisis (MC) requires admission of the patient into a neurological intensive care unit and timely institution of an efficient and safe treatment. Despite the growing clinical experience with disease modifying immunotherapy there is no clinical consensus regarding the use of plasma exchange or high dose immunoglobulin treatment in an ICU setting. The choice of treatment modalities seem to rely mostly on institutional preferences primarily due to a lack of well-designed clinical trials comparing currently available therapeutic options. In our experience and based on a review of recent literature we advocate the use of plasma exchange (PE) as a primary modality in the acute care setting, supported by other immunomodulatory medications such as corticosteroids. Pharmacological management cannot substitute for adequate intensive care management of the respiratory and bulbar insufficiency associated with MC. Every effort should be done to prevent myasthenic exacerbation/crisis and to develop a maintenance management that leads to effective prevention.

Beneficial Effect of Tacrolimus on Myasthenia Gravis With Thymoma

We examined the effect of tacrolimus on myasthenia gravis (MG). Five patients with thymoma and 5 patients without thymoma underwent prior thymectomy but showed persistent myasthenic symptoms. Oral administration with tacrolimus significantly improved MG scores 1, 3, and 6 months following the beginning of treatment in all patients (P < 0.05), and the improvement was significantly higher in the thymoma group compared with the nonthymoma group (P < 0.05). However, there was no significant change in antiacetylcholine receptor titers in either group. This indicates a particular application of immunosuppressive therapy for thymomatous MG following thymectomy.

A Diagnostic and Management Dilemma

BACKGROUND

Neuromuscular junction disorders are usually categorized as either presynaptic or postsynaptic. The most frequently encountered disorder of the postsynaptic neuromuscular junction is acquired myasthenia gravis. Lambert-Eaton myasthenic syndrome is a well-known prototype of the presynaptic autoimmune disorders of neuromuscular transmission. These major disorders of neuromuscular transmission are relatively common and distinctly recognized, but co-occurrence of these disorders (overlap myasthenic syndrome) is rare and has so far attracted little attention.

REVIEW SUMMARY

This report describes a patient with acquired myasthenia gravis and immunologic coexistence of Lambert-Eaton myasthenic syndrome (overlap myasthenic syndrome) in association with abdominal/uterine leiomyosarcoma. The patient presented with acute respiratory failure, making identification and management of her illness challenging. A general overview of the complexities associated with overlap between myasthenia gravis and Lambert-Eaton myasthenic syndrome is provided and this patient's complicated clinical course and response to therapy are discussed.

CONCLUSION

To our knowledge, this is the first report of overlap myasthenic syndrome in conjunction with abdominal leiomyosarcoma. The immunologic coexistence of acquired myasthenia gravis and Lambert-Eaton myasthenic syndrome in a patient with a malignant smooth-muscle tumor is intriguing and suggests that a common paraneoplastic process targeting 2 different onconeural antigens was the underlying pathogenic mechanism in this patient.

Inhibition of IL-6 overproduction by steroid treatment before transsternal thymectomy for myasthenia gravis: does it help stabilize perioperative condition?

Overproduction of interleukin (IL)-6 plays an important role in the pathophysiology of myasthenia gravis (MG), and thymectomy can cause myasthenic crisis because of surgically induced overproduction of IL-6. Preoperative steroid therapy is beneficial in preventing MG crisis during the perioperative period. The purpose of this study was to clarify the effect of preoperative steroid therapy on proinflammatory mediators during the perioperative period of transsternal thymectomy for MG. The study group comprised 20 consecutive MG patients undergoing transsternal thymectomy during the period March 2002 through March 2004. Seventeen of these patients received dose-escalated steroid therapy before thymectomy (steroid treatment group) and three did not (non-steroid treatment group). Serum concentrations of C-reactive protein (CRP) and IL-6 were determined during the perioperative period; clinical outcomes were reviewed, and the results were compared between the two groups. Peak serum IL-6 and CRP concentrations were significantly lower in the steroid treatment group than in the non-steroid treatment group. Amongst perioperative variables subjected to multiple regression analysis, preoperative steroid treatment were found to be the most significant independent predictor of inhibited IL-6 production on postoperative day 1. No postoperative respiratory failure occurred in the steroid treatment group, but it did occur in the non-steroid treatment group. Preoperative steroid therapy can ameliorate IL-6 overproduction and may help stabilize the patient's postoperative condition.

Corticosteroids for myasthenia gravis

BACKGROUND

Although widely accepted as an appropriate immunosuppressive therapy, the efficacy of glucocorticosteroid treatment has only rarely been tested in controlled studies.

OBJECTIVES

To assess the efficacy of glucocorticosteroids or adrenocorticotrophic hormone (ACTH) medication in autoimmune myasthenia gravis.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register in July 2004, MEDLINE (from January 1966 to June 2004) and EMBASE (from January 1980 to June 2004). We also checked the bibliographies in reviews and the randomised trials and contacted their authors to identify additional published and unpublished data.

SELECTION CRITERIA

From the articles identified we selected those open or controlled studies which allowed us to assess the outcome of treated and untreated patients at definite endpoints. Types of studies: quasi-randomised or randomised controlled trials.

TYPES OF PARTICIPANTS

patients with myasthenia gravis of all ages and all degrees of severity. Types of interventions: any form of glucocorticosteroids or adrenocorticotrophic hormone treatment. Types of outcome measures:Primary outcome(1) improvement after at least three months in either the weakest muscles or all muscles. Secondary outcomes(1) proportion of patients improved after at least six months(2) proportion of patients in remission(3) number of episodes of worsening during the first six months(4) acetylcholine receptor antibody titres after at least three months of therapy.

DATA COLLECTION AND ANALYSIS

Three authors extracted the data from the selected articles and one other checked them.

MAIN RESULTS

A trial of adrenocorticotrophic hormone (43 patients) did not show any advantage compared with placebo for the treatment of ocular myasthenia gravis. Two double-blind trials compared prednisone with placebo for generalised myasthenia gravis. In the first (13 patients), the improvement was slightly greater in the prednisone group at six months. In the second (20 patients) which was a short-term trial, the improvement was significantly greater at two weeks. Two trials compared glucocorticosteroids with azathioprine (41 and 10 patients respectively). In one of these the rate of treatment failure was greater in the prednisone group. In a trial of glucocorticosteroids versus intravenous immunoglobulin (33 patients) no differences in treatment responses were encountered during a treatment period of 14 days. An open trial (39 patients) evaluating different corticosteroid doses revealed a shorter time to improvement in the high-dose group. However only limited evidence can be drawn from the available randomised controlled trials due to numerous and important methodological flaws.

AUTHORS' CONCLUSIONS

Limited evidence from randomised controlled trials suggests that corticosteroid treatment offers significant short-term benefit in myasthenia gravis compared with placebo. This supports the conclusions of observational studies and expert opinion. Limited evidence from randomised controlled trials does not show any difference in efficacy between corticosteroids and either azathioprine or intravenous immunoglobulin.

High frequency of allergic conjunctivitis in myasthenia gravis without thymoma

OBJECTIVES

To investigate the frequency of allergic disorders in myasthenia gravis (MG) patients and characterize the features of MG associated with allergic disorders.

METHODS

Frequencies of past and present common allergic disorders in 160 MG patients who visited the Department of Neurology, Kyushu University Hospital from April 2000 to July 2003 and in 81 neurological normal controls were studied.

RESULTS

Among various allergic disorders, the frequency of allergic conjunctivitis (AC) was significantly higher in MG patients (39/160, 24.4%, p(corr)=0.0112), especially with MG without thymoma (36/123, 29.3%, p(corr)=0.0016), in comparison to the controls (6/81, 7.4%). MG patients with AC showed a significantly higher rate of seronegative MG (43.6% vs. 17.4%, p=0.008) and a higher tendency of ocular MG (43.6% vs. 28.1%, p=0.071). Moreover, MG with AC had significantly lower anti-acetylcholine receptor antibody titers (median 6.8 nmol/l vs. median 23.6 nmol/l, p=0.0359) as well as a lower rate of coexisting thymoma (7.7% vs. 17.4%, p=0.016). The incidence of myasthenic crisis was also lower in MG with AC than without AC, yet the difference was not significant (7.7% vs. 15.7%).

CONCLUSION

There was a significant association of AC with MG especially for ocular or seronegative MG in cases without thymoma.

HLA genotypes in turkish patients with myasthenia gravis: Comparison with multiple sclerosis patients on the basis of clinical subtypes and demographic features

The nature and intensity of the association of myasthenia gravis (MG) with distinct human leukocyte antigens (HLA) haplotypes differ between ethnic populations. The aims of the present study were to examine the relationship between HLA class I and II haplotypes and MG; to show the HLA associations with various MG subsets; and to investigate the association between MG and clinical subgroups of multiple sclerosis (MS) regarding HLA haplotypes. A total of 66 patients with MG were enrolled onto the study. The mean age at onset was 42.01 years. A total of 122 clinically definite MS patients and 188 healthy subjects were examined as control groups. The present study clearly showed associations with HLA-DR3, -B8, -A1, and -A2 in MG. In patients with early-onset MG, associations with HLA-DR3, -B8, and -A2 were stronger. When compared with MS, in the MG group, there was still a strong association with -B8, -DR3, and -A1. In subgroup analysis, there was no difference between MG and primary progressive MS patients. On the basis of the presence of anti-AChR antibodies, there was a statistically significant association with HLA-DR3. On the basis of presence of thymoma, no HLA allele showed clear associations in MG patients with thymoma. This is the first study to examine the relationship between HLA haplotypes and MG in the Turkish population and to compare MG with another autoimmune disease, MS, on the basis of the HLA haplotypes. Further investigations with a larger population are required to explain this finding.

Prognostic factors for myasthenic crisis after transsternal thymectomy in patients with myasthenia gravis

OBJECTIVE

The purpose of this study was to assess which clinical features of patients with myasthenia gravis predict postoperative respiratory problems due to myasthenic crisis after transsternal thymectomy.

METHODS

One hundred twenty-two patients who underwent transsternal thymectomy in our institute were analyzed retrospectively. Fourteen of those experienced myasthenic crisis and required prolonged (48 hours or more) postoperative mechanical ventilation. The following factors were evaluated: sex, age, body mass index, grade of symptom, disease interval, existence of thymoma, history of preoperative crisis, doses of anticholinesterase drugs, steroid use, pulmonary function, serum anti-acetylcholine receptor antibody, history of pulmonary disease, presence of other disease, operation time, and blood loss.

RESULTS

Univariate analysis revealed preoperative bulbar symptoms (odds ratio = 14.246, P =.001), history of preoperative myasthenic crisis (7.091,.018), and preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L (4.098,.044) were prognostic factors for postoperative myasthenic crisis. On the other hand, multivariate logistic regression analysis revealed preoperative bulbar symptoms (33.333,.004), preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L (7.874,.020), and intraoperative blood loss > 1000 mL (18.519,.048) were prognostic factors for postoperative myasthenic crisis.

CONCLUSIONS

In this study, postoperative myasthenic crisis after transsternal thymectomy in 122 patients with myasthenia gravis was affected by the existence of preoperative bulbar symptoms, history of preoperative myasthenic crisis, preoperative serum level of anti-acetylcholine receptor antibody > 100 nmol/L, and intraoperative blood loss > 1000 mL. Meticulous preoperative and postoperative care should be carried out to prevent postoperative myasthenic crisis in patients with these prognostic factors.

Appearance of systemic lupus erythematosus in patients with myasthenia gravis following thymectomy: two case reports

We report two cases of systemic lupus erythematosus (SLE) in myasthenia gravis (MG) patients who had undergone thymectomy. SLE developed in the patients 3 months or 13 yr after thymectomy, and polyarthritis was the main clinical manifestation of SLE. Both patients fulfilled at least four of the revised criteria for the classification of SLE. In this report, we describe two postthymectomy lupus patients and perform a comparative review of previous cases.

Successful treatment of refractory myasthenia gravis using rituximab: a pediatric case report

We report the successful use of anti-CD20 therapy in a child with refractory myasthenia gravis (MG), an antibody-mediated autoimmune disease, who did not respond to conventional therapy. After initiation of anti-CD20 therapy, clinical improvement (muscular strength, pulmonary function) was observed.

Critical care management of neuromuscular disease, including long-term ventilation

PURPOSE OF REVIEW

This review highlights recent advances in the critical care management of neuromuscular disease, particularly in the long-term management of chronic respiratory failure occurring as a consequence of neuromuscular disease.

RECENT FINDINGS

Although randomized clinical trial evidence of benefit is sparse, a large volume of nonrandomized clinical trial evidence has accumulated demonstrating that noninvasive positive pressure ventilation prolongs and improves quality of life in conditions such as Duchenne muscular dystrophy and motor neuron disease.

SUMMARY

Immunomodulatory treatments favorably modify the course of neuromuscular diseases such as Guillain-Barré syndrome, whereas long-term noninvasive positive pressure ventilation has transformed the outlook in previously untreatable conditions such as motor neuron disease and muscular dystrophies. The availability of long-term noninvasive positive pressure ventilation raises major medical, social, economic, and ethical issues that are increasingly being investigated and discussed.

Intravenous immunoglobulin monotherapy in long-term treatment of myasthenia gravis

OBJECTIVE

To investigate effectiveness of long-term treatment of myasthenia gravis (MG) with intravenous immunoglobulin (IVIG).

BACKGROUND

There are no definitive studies showing effectiveness of IVIG therapy in long-term treatment of MG. Most studies have investigated the acute treatment of MG with IVIG. We describe our experience with long-term treatment of MG with IVIG in six patients.

METHODS

Acute treatment of MG by IVIG therapy has been well established in the literature. We describe six patients who were treated on a long-term basis with IVIG therapy. All of these patients had positive acetylcholine receptor antibody titers. They all received initial infusion for 5 days of IVIG at a dose of 400 mg/kg/day followed by maintenance therapy of 400 mg/kg for 1 day every 3-4 months. These patients were followed for 2 years. All other medications, including prednisone and cholingeric drugs such as Mestinon, were gradually weaned. For the last years, each of these patients maintained better than functional class 2 on an average of 1.5-2.2+/-0.5 grades on the University of Virginia modification of Ossermann's classification scale for MG. They were solely treated with IVIG infusion every 3-4 months without any other concomitant medications. Three of the patients had previously undergone thymectomies. None of the patients noticed any worsening in their scores on the University of Virginia modification of Ossermann's classification worse than Grade II in the last 2 years. There were no complications related to IVIG therapy, and all patients tolerated a single infusion of IVIG every 3-4 months at 400 mg/kg for 1 day.

RESULTS

Our study demonstrates that IVIG maintenance is effective treatment of MG in selected patients and it is well tolerated.

CONCLUSIONS

IVIG therapy is a convenient, effective therapy when used selectively for treatment of MG on a long-term basis without any significant side effects.

Heterogeneous immunogenetic background in Japanese adults with myasthenia gravis

The aim of this study was to elucidate the roles of human leukocyte antigen (HLA) class II genes in disease susceptibility in Japanese adult patients with myasthenia gravis (MG). A number of studies have shown that MG is correlated with DR3 in Caucasians. In Japanese, infantile MG is associated with DR9, but the HLA class II alleles associated with adult MG remains unclear. HLA-DRB1 and DQB1 alleles were determined by genotyping in 75 Japanese adult patients with MG and in 115 race-matched healthy adults. No statistically significant difference was observed in the overall prevalences of DRB1 and DQB1 alleles between MG patients and healthy controls, even when the patients and controls were stratified on the basis of their gender. MG patients with DQB1*0604 were younger and those with DQB1*0402 were older at disease onset than those without (P=0.03 and 0.008, respectively). Concomitant autoimmune thyroid disease was associated with DRB1*0803 (P=0.0009, corrected P=0.04). In addition, anti-acetylcholine receptor antibody levels were significantly higher in patients with DQB1*0604 than in those without (P=0.045). These findings indicate that immunogenetic backgrounds in Japanese adult MG patients are heterogeneous and are apparently different from those in Caucasian patients.

Anti-CTLA-4 antibody treatment triggers determinant spreading and enhances murine myasthenia gravis

CTLA-4 appears to be a negative regulator of T cell activation and is implicated in T cell-mediated autoimmune diseases. Experimental autoimmune myasthenia gravis (EAMG), induced by immunization of C57BL/6 mice with acetylcholine receptor (AChR) in adjuvant, is an autoantibody-mediated disease model for human myasthenia gravis (MG). The production of anti-AChR Abs in MG and EAMG is T cell dependent. In the present study, we demonstrate that anti-CTLA-4 Ab treatment enhances T cell responses to AChR, increases anti-AChR Ab production, and provokes a rapid onset and severe EAMG. To address possible mechanisms underlying the enhanced autoreactive T cell responses after anti-CTLA-4 Ab treatment, mice were immunized with the immunodominant peptide alpha(146-162) representing an extracellular sequence of the ACHR: Anti-CTLA-4 Ab, but not control Ab, treatment subsequent to peptide immunization results in clinical EAMG with diversification of the autoantibody repertoire as well as enhanced T cell proliferation against not only the immunizing alpha(146-162) peptide, but also against other subdominant epitopes. Thus, treatment with anti-CTLA-4 Ab appears to induce determinant spreading, diversify the autoantibody repertoire, and enhance B cell-mediated autoimmune disease in this murine model of MG.

Plasma exchange for treatment of myasthenia gravis: pathophysiologic basis and clinical experience

Myasthenia gravis is an autoimmune disease characterized by production of antibodies to acetylcholine receptors located at the motor end plate in skeletal muscles. The antibodies bind and subsequently induce degeneration of these receptors. Loss of acetylcholine receptors results in inadequate contraction of muscle fibers in response to acetylcholine released from nerve terminals and clinically apparent muscle weakness. Plasma exchange removes the circulating antibodies in myasthenic patients with short-term clinical improvement. Plasma exchange may be indicated in patients with acute exacerbation of neuromuscular weakness with bulbar or respiratory compromise, preoperative optimization prior to thymectomy, and postoperative deterioration following thymectomy or other surgical procedures. Long-term, intermittent plasma exchange for patients who do not adequately respond to standard treatment is another evolving indication.

Therapeutic apheresis in myasthenia gravis

Plasma exchange (PE) is an easily applicable technique for rapid and massive removal of antibodies, and its beneficial role is well established in the management of myasthenia gravis (MG), an antibody-mediated disorder of the neuromuscular junction. PE is useful in myasthenic crisis, in most severe forms of MG before thymectomy, in the early postoperative period, and in cases of symptom worsening during tapering or initiation of immunosuppressive therapy. Clinical efficacy varies from 55% to 100%, and improvement rarely persists for more than 4-10 weeks; thus immunosuppressive therapy has to be associated. New apheretic techniques (double filtration plasmapheresis, immunoadsorption systems with staphylococcal protein A columns or thryptophan-polyvinyl alcohol gel columns) that allow the selective removal of IgG and anti-AChR antibody were recently used in the management of MG with positive effects. Whether their therapeutic effect and cost effect prove more favorable than those obtained by PE still must be demonstrated.

Plasmapheresis by using secondary membrane filters: twelve years of experience

Over 1,600 plasmapheresis procedures have been performed by using secondary on-line membrane plasma filters in 62 patients over the past 12 years in our institution. The disease categories treated include cryoprotein induced diseases such as cryoglobulinemia, immune mediated disorders, and familial type II-A hypercholesterolemia (FHC). Depending upon the molecular size of the offending agent, we used plasma filters (PF) with different pore sizes ranging from 0.02 microm to 0.04 microm or the cryoglobulin filter (CF) with an average pore size of 4.3 microm to remove cryoprecipitable proteins. One plasma volume was processed in each treatment. The results of treating 25 patient in over 550 procedures by using PF show it is safe and effective in treating immune mediated disorders and FHC. PF selectively removes macromolecules according to pore size and are more specific for the treatment of immune mediated diseases and FHC than plasma exchange. The results of treating 37 patients in over 1,100 procedures by using CF show it is safe and effective in selectively removing cryoproteins, and it is very specific for the treatment of cryoprotein induced diseases. Both PF and CF are biocompatible, with no complement activation. Unlike plasma exchange, secondary membrane plasma filters do not cause deficiency syndromes and do not require albumin or fresh frozen plasma as replacement fluid, making them more cost effective than plasma exchange.

Predictable recovery from myasthenia gravis crisis with plasma exchange: thirty-six cases and review of current management

Adult, acquired, idiopathic, autoimmune myasthenia gravis has a well-characterized IgG anti-acetylcholine striated-muscle receptor antibody. Removal by plasma exchange is effective, established therapy to augment anti-cholinesterase and immunosuppressive therapy and is the treatment of choice for myasthenia gravis crisis. We report 36 consecutive patients referred and accepted for plasma exchange, 32 of whom were in or entering myasthenia crisis, over a 10 year period. An average of 7.8 (range 1 to 16) plasma exchange procedures were done, with uniform, significant improvement, including extubation of 13 in myasthenic crisis and discharge from hospital in all. We conclude that this is the best treatment for myasthenia gravis crisis in hospital. From recent cases, most, if not all, crises can be prevented by IVIgG or plasma exchange as out-patients with use of corticosteroid and or azathioprine.

Multiple sclerosis--in need of a critical reappraisal

Multiple sclerosis (MS) is a disease that currently defies clinical and scientific definitions. Despite intensive clinical and basic research, very little is known about its possible cause(s) or pathogenesis, and the course and prognosis of MS practically remain unchanged. The aim of the present article is to outline some of the reasons for the constant failure to improve the therapy of MS. It also attempts to offer several guidelines which may enable a fresh and different approach to this devastating condition.

Myasthenic crisis with delayed recovery after plasmapheresis

We report on 2 elderly patients with myasthenia gravis in whom recovery from crisis was prolonged despite intensive plasmapheresis (PP). In both patients, the anti-acetylcholine (anti-AChR) titer failed to fall sufficiently after completing PP. These patients might have had antibodies that produced a more pronounced effect on the degradation of AChR, or the synthesis of AChR might have been reduced by aging. The anti-AChR titer did not correlate with a reduction of IgG after PP in 1 patient. Successful treatment was achieved by keeping the anti-AChR titer at a low level via the concomitant use of prednisolone with PP.

Myasthenia Gravis

The treatment of patients with myasthenia gravis should be individualized according to the extent (ocular versus generalized) and severity (mild to severe) of disease, the presence or absence of concomitant disease (including but not limited to other autoimmune diseases and thymoma), and, to a lesser degree, the age of the patient. Thymectomy should be performed in patients with generalized disease, especially those who have detectable levels of circulating antibodies to acetylcholine receptor (anti-AChR), as it should be in all patients thought to have an operable thymoma (observed on imaging studies of the chest). Symptomatic therapy consists of anticholinesterase drugs (usually pyridostigmine); occasionally, other drugs are required to reduce the muscarinic side effects. At times, patients need immunosuppressive or immunomodulatory therapy with glucocorticoids, azathioprine, cyclospor-ine or cyclophosphamide, plasma exchange, and intravenous immunoglobulin. Remission, whether spontaneous or pharmacologically induced, or significant improvement can be achieved in most patients, but some treatments entail significant side effects and considerable cost.

The role of B-cells in experimental myasthenia gravis in mice

Myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG) are caused by auto-antibodies against the nicotinic acetylcholine receptor (AChR) at the postsynaptic membrane. To evaluate the extent to which the humoral immune response against AChR operates in the pathogenesis of EAMG, we immunized B-cell knockout (microMT) and wild type C57BL/6 mice with AChR in complete Freund's adjuvant. The ability of AChR-primed lymph node cells to proliferate and secrete IFN-gamma in response to AChR and its dominant peptide alpha 146-162 were intact in microMT as in wild type mice. Similar levels of mRNA for IFN-gamma, IL-4 and IL-10 in AChR-reactive lymph node cells were detected in microMT and wild type mice. However, microMT mice had no detectable anti-AChR antibodies and never developed clinical EAMG. We conclude that B-cells are critically required for the genesis of clinical EAMG, but not for AChR-specific T-cell priming.

Long-term immunologic effects of thymectomy in patients with myasthenia gravis

BACKGROUND

Thymectomy (Tx) is a common therapeutic option to treat myasthenia gravis (MG), but its effects on the immune system are still obscure in humans.

OBJECTIVE

We sought to evaluate long-term immunologic effects of therapeutic Tx in patients with MG.

METHODS

T- and B-cell subsets and T-cell repertoire were analyzed in 35 patients with MG, 16 with previous Tx (at least 8 years before), 6 with recent (<1 year) Tx, and 13 without Tx, as well as in 32 healthy subjects used as normal control subjects. Serum immunoglobulins and a variety of autoantibodies were also measured. A subsequent 3-year clinical follow-up was performed to verify the possible appearance of systemic autoimmune diseases.

RESULTS

The long-term thymectomized (Txd) patients had mild T-cell lymphopenia and an expansion of some Vbeta families among circulating CD4+ and CD8+ T cells. They displayed a normal number of total B and CD5+ B-circulating lymphocytes, but they also displayed a polyclonal increase in serum IgM and IgG associated with the presence of high levels of a variety of organ- and nonorgan-specific autoantibodies, including anti-dsDNA and anticardiolipin, without clinical evidence of autoimmune disease. These serologic abnormalities were not detectable in both non-Txd and recently Txd patients. After 3 years, 2 long-term Txd patients had systemic lupus erythematosus and an undifferentiated connective tissue disease.

CONCLUSIONS

The association between MG and laboratory findings of systemic autoimmune disease may be in part related to Tx rather than to MG. Tx may represent a risk for the development of systemic autoimmune disorders over years in patients with MG.

No evidence for interleukin-4 gene conferring susceptibility to myasthenia gravis

A variable number of tandem repeat (VNTR) and a dinucleotide repeat polymorphism in IL-4 gene were examined in Swedish myasthenia gravis (MG) patients and ethnically matched healthy individuals. There were no associations between these polymorphisms and MG patients as a whole group or stratified by clinical and pathological parameters and genetic markers in MHC gene (TNF-alpha NcoI allele 2) and IL-1 gene (IL-1beta TaqI allele 2). This lack of association between the IL-4 gene and disease contrasts to our previous results showing that MG is associated with higher secretor phenotypes of two prototype proinflammatory cytokine (TNF-alpha and IL-1) genes.

Selective impairment of serum antibody repertoires toward muscle and thymus antigens in patients with seronegative and seropositive myasthenia gravis

We analyzed the antibody (Ab) repertoires of IgM and IgG of patients with seropositive and patients with seronegative myasthenia gravis (MG) toward self antigens by means of a quantitative immunoblotting technique using normal human tissue extracts as sources of self antigens. Repertoires of reactivities of IgG and IgM with liver, kidney and stomach antigens were conserved between myasthenic patients and controls. IgG and IgM Ab repertoires toward muscle antigens differed significantly between patients with seropositive MG and healthy donors, as assessed by multiparametric statistical analysis. Patterns of Ab reactivities to muscle antigens were similar in patients with seronegative MG and healthy controls. Antibody repertoires of IgG and IgM toward thymus antigens of both seropositive and seronegative MG patients, differed significantly from those of healthy individuals. Our results indicate that MG is characterized by a selective impairment of self-reactive Ab repertoires toward muscle and thymus antigens. The observation that self-reactive Ab repertoires toward thymus antigens are similar in patients with seropositive and seronegative MG suggests that both forms of MG share common immunopathological features.

Expression of CD23 in the germinal center of thymus from myasthenia gravis patients

In order to investigate a pathogenic role of germinal centers which appear in the hyperplastic thymus of myasthenia gravis (MG) patients, we performed an immunohistochemical study using various monoclonal antibodies including CD23. In contrast with tonsilar germinal centers from non-MG individuals, CD23 was strongly and diffusely expressed in the whole area of germinal centers of MG thymi, including the outer zone. In addition, we measured the serum level of soluble CD23 (sCD23) in MG patients at various clinical stages. The high serum sCD23 levels, which were noted in the unthymectomized patients, fell to within normal range over 5 years after thymectomy, and the decline of serum sCD23 correlated well with clinical improvement. CD23 is thought to be responsible for preventing unselected germinal center B cells from entering apoptosis and, in turn, leads to the survival of auto-reactive B cell clones.