Guidelines for treatment of autoimmune neuromuscular transmission disorders

Pathophysiology and immunological profile of myasthenia gravis and its subgroups

Myasthenia gravis (MG) is an autoimmune antibody-mediated disease characterized by muscle weakness and fatigability. It is believed that the initial steps triggering humoral immunity in MG take place inside thymic tissue and thymoma. The immune response against one or several epitopes expressed on thymic tissue cells spills over to neuromuscular junction components sharing the same epitope causing humoral autoimmunity and antibody production. The main cause of MG is acetylcholine receptor antibodies. However, many other neuromuscular junction membrane protein targets, intracellular and extracellular proteins are suggested to participate in MG pathophysiology. MG should be divided into subgroups based on clinical presentation and immunology. This includes onset age, clinical characteristics, thymic pathology and antibody profile. The immunological profile of these subgroups is determined by the antibodies present.

Tacrolimus in the treatment of myasthenia gravis in patients with an inadequate response to glucocorticoid therapy: randomized, double-blind, placebo-controlled study conducted in China

Background

To determine the efficacy of low-dose, immediate-release tacrolimus in patients with myasthenia gravis (MG) with inadequate response to glucocorticoid therapy in a randomized, double-blind, placebo-controlled study.

Methods

Eligible patients had inadequate response to glucocorticoids (GCs) after ⩾6 weeks of treatment with prednisone ⩾0.75 mg/kg/day or 60–100 mg/day. Patients were randomized to receive 3 mg tacrolimus or placebo daily (orally) for 24 weeks. Concomitant glucocorticoids and pyridostigmine were allowed. Patients continued GC therapy from weeks 1–4; from week 5, the dose was decreased at the discretion of the investigator. The primary efficacy outcome measure was a reduction, relative to baseline, in quantitative myasthenia gravis (QMG) score assessed using a generalized linear model; supportive analyses used alternative models.

Results

Of 138 patients screened, 83 [tacrolimus (n = 45); placebo (n = 38)] were enrolled and treated. The change in adjusted mean QMG score from baseline to week 24 was −4.9 for tacrolimus and −3.3 for placebo (least squares mean difference: –1.7, 95% confidence interval: −3.5, −0.1; p = 0.067). A post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group (68.2%) versus the placebo group (44.7%; p = 0.044). Adverse event profiles were similar between treatment groups.

Conclusions

Tacrolimus 3 mg treatment for patients with MG and inadequate response to GCs did not demonstrate a statistically significant improvement in the primary endpoint versus placebo over 24 weeks; however, a post-hoc analysis demonstrated a statistically significant difference for QMG score reduction of ⩾4 points in the tacrolimus group versus the placebo group. This study was limited by the low number of patients, the absence of testing for acetylcholine receptor antibody and the absence of stratification by disease duration (which led to a disparity between the two groups).

ClinicalTrials.gov identifier: NCT01325571

Outcomes of Preoperative and Postoperative Corticosteroid Therapies in Myasthenia Gravis

AIMS

To compare the long-term outcomes of non-thymomatous myasthenia gravis (MG) patients receiving pre-thymectomy (Pre-CS) or post-thymectomy corticosteroid (Post-CS) therapy.

METHODS

In a retrospective cohort study, 41 patients with MG were treated with Pre-CS therapy, and 110 were treated with Post-CS therapy.

RESULTS

In the MG cohorts, 9 of 40 patients (22.5%) in the Pre-CS group vs. 28 of 105 patients (26.7%) in the Post-CS group achieved a complete remission (CR) at 1 year, 29.7% (11/37) vs. 38.6% (32/83) at 2 years and 36.4% (8/22) in the Pre-CS group vs. 50.0% (28/56) in the Post-CS group achieved a CR at 5 years. For the entire population, Post-CS therapy (hazard rate [HR] 3.042, p = 0.020) was a positive predictor for remission, and a long preoperative interval (HR 0.936, p = 0.030) was a negative predictor. In 98 original ocular MG patients, Post-CS therapy (HR 2.663, p = 0.014) and an age at onset ≥15 years (HR 4.865, p = 0.001) were positive predictors for remission.

DISCUSSION

Post-CS therapy with a shorter preoperative interval increases the likelihood of CR in postpubertal and adult patients.

Factors affecting outcome in ocular myasthenia gravis

AIM OF THE STUDY

50%-60% of patients with ocular myasthenia gravis (OMG) progress to generalized myasthenia gravis (GMG) within two years. The aim of our study was to explore factors affecting prognosis of OMG and to test the predictive role of several independent clinical variables.

MATERIALS AND METHODS

We reviewed a cohort of 168 Caucasian patients followed from September 2000 to January 2016. Several independent variables were considered as prognostic factors: gender, age of onset, results on electrophysiological tests, presence and level of antibodies against acetylcholine receptors (AChR Abs), treatments, thymic abnormalities. The primary outcome was the progression to GMG and/or the presence of bulbar symptoms. Secondary outcomes were either achievement of sustained minimal manifestation status or worsening in ocular quantitative MG subscore (O-QMGS) or worsening in total QMG score (T-QMGS), assessed by Myasthenia Gravis Foundation of America (MGFA) quantitative scores. Changes in mental and physical subscores of health-related quality of life (HRQoL) were assessed with SF-36 questionnaire. Variance analysis was used to interpret the differences between AChR Ab titers at different times of follow up among the generalized and non-generalized patients.

RESULTS

Conversion to GMG occurred in 18.4% of patients; it was significantly associated with sex, later onset of disease and anti-AChR Ab positivity. Antibody titer above the mean value of 25.8 pmol/mL showed no significant effect on generalization. Sex and late onset of disease significantly affected T-QMGS worsening. None of the other independent variables significantly affected O-QMGS and HRQoL.

CONCLUSIONS

Sex, later onset and anti-AChR Ab positivity were significantly associated with clinical worsening.

Outcomes after major surgery in patients with myasthenia gravis: A nationwide matched cohort study

Objective

To validate the comprehensive features of adverse outcomes after surgery for patients with myasthenia gravis.

Methods

Using reimbursement claims from Taiwan’s National Health Insurance Research Database, we analyzed 2290 patients who received major surgery between 2004 and 2010 and were diagnosed with myasthenia gravis preoperatively. Surgical patients without myasthenia gravis (n = 22,900) were randomly selected by matching procedure with propensity score for comparison. The adjusted odds ratios and 95% confidence intervals of postoperative adverse events associated with preoperative myasthenia gravis were calculated under the multiple logistic regressions.

Results

Compared with surgical patients without myasthenia gravis, surgical patients with myasthenia gravis had higher risks of postoperative pneumonia (OR = 2.09; 95% CI: 1.65–2.65), septicemia (OR = 1.31; 95% CI: 1.05–1.64), postoperative bleeding (OR = 1.71; 95% CI: 1.07–2.72), and overall complications (OR = 1.70; 95% CI: 1.44–2.00). The ORs of postoperative adverse events for patients with myasthenia gravis who had symptomatic therapy, chronic immunotherapy, and short-term immunotherapy were 1.76 (95% CI 1.50–2.08), 1.70 (95% CI 1.36–2.11), and 4.36 (95% CI 2.11–9.04), respectively.

Conclusions

Patients with myasthenia gravis had increased risks of postoperative adverse events, particularly those experiencing emergency care, hospitalization, and thymectomy for care of myasthenia gravis. Our findings suggest the urgency of revising protocols for perioperative care for these populations.

Perioperative Management of Neurological Conditions

Perioperative care of the patients with neurological diseases can be challenging. Most important consideration is the management and understanding of pathophysiology of these disorders and evaluation of new neurological changes that occur perioperatively. Perioperative generally refers to 3 phases of surgery: preoperative, intraoperative, and postoperative. We have tried to address few commonly encountered neurological conditions in clinical practice, such as delirium, stroke, epilepsy, myasthenia gravis, and Parkinson disease. In this article, we emphasize on early diagnosis and management strategies of neurological disorders in the perioperative period to minimize morbidity and mortality of patients.

The Role of Osteopontin and Its Gene on Glucocorticoid Response in Myasthenia Gravis

Biomarkers that assess treatment response for patients with the autoimmune disorder, myasthenia gravis (MG), have not been evaluated to a significant extent. We hypothesized the pro-inflammatory cytokine, osteopontin (OPN), may be associated with variability of response to glucocorticoids (GCs) in patients with MG. A cohort of 250 MG patients treated with standardized protocol of GCs was recruited, and plasma OPN and polymorphisms of its gene, secreted phosphoprotein 1 (SPP1), were evaluated. Mean OPN levels were higher in patients compared to healthy controls. Carriers of rs11728697*T allele (allele definition: one of two or more alternative forms of a gene) were more frequent in the poorly GC responsive group compared to the GC responsive group indicating an association of rs11728697*T allele with GC non-responsiveness. One risk haplotype (AGTACT) was identified associated with GC non-responsiveness compared with GC responsive MG group. Genetic variations of SPP1 were found associated with the response to GC among MG patients.

A multicenter prospective observational study on the safety and efficacy of tacrolimus in patients with myasthenia gravis

INTRODUCTION

Several clinical studies using tacrolimus revealed reasonable therapeutic mechanisms and efficacy in patients with myasthenia gravis (MG). However, long-period studies in a large number of patients with MG are limited; therefore, the aim of this study was to investigate the therapeutic efficacies and safety of tacrolimus in patients with MG during a 12-month follow-up period.

METHODS

Tacrolimus was administered to 150 patients with MG who were recruited based on the inclusion criteria. Fifteen medical centers in Korea participated in this study. The efficacy of tacrolimus was assessed using MG composite scales (MGCS) and the prednisolone-sparing effect. And the adverse drug reactions (ADRs) of tacrolimus were monitored in each patient from the beginning of tacrolimus treatment to the end of the follow-up period.

RESULTS

After starting tacrolimus, the 32 patients were affected by ADRs, and consequentially 134 patients of the enrolled patients were followed up for 12months. They showed that the mean prednisolone dosage significantly decreased (6.1±7.6mg/day), compared to that in the baseline (11.3±9.5mg/day), and MGCS significantly improved after 12months of tacrolimus treatment, compared to that at the baseline.

CONCLUSIONS

Our study showed that tacrolimus would be an effective immunosuppressant as an initial therapeutic agent in patients with MG; in addition, it showed tolerable safety profiles during the 12-month follow-up evaluation.

Aggregated N-of-1 trials for unlicensed medicines for small populations: an assessment of a trial with ephedrine for myasthenia gravis

Background

Inexpensive medicines with a long history of use may currently be prescribed off-label for rare indications. Reimbursement is at the discretion of health insurance companies, and may be unpredictable. The example addressed was ephedrine as add-on treatment for myasthenia gravis. Stakeholders from academia, a patient organization, the Dutch National Health Care Institute (NHCI) and Dutch Medicines Evaluation Board (MEB) advised on the trial design. The NHCI and MEB agreed to provide scientific advice on the suitability of the evidence generated by the trial, for regulatory decisions. This paper describes the feasibility of the trial and the utility of its aggregated results.

Results

The trialists experienced the trial as feasible. Retrospective interviews showed that the trial as performed was acceptable to patients. The treatment effect in the primary outcome measure, muscle strength, was statistically significant when inferred to the population level, though the effect size was modest. Secondary outcomes were statistically significant in a preplanned, fixed effects analysis within the four patients. The NHCI advised that it could potentially make reimbursement decisions based on the Fitting Evidence framework, should the trialists decide to apply for reimbursement. The MEB advised that for a licensing decision, the N-of-1 design is a last-resort option for demonstrating treatment benefit in a rare disease. N-of-1 trials alone do not provide enough evidence on potential risk. The MEB found the current trial inconclusive. It suggested doing a 2-armed trial of longer duration, possibly with a different outcome measure (postponement of corticosteroid use). It suggested engaging a consultancy or commercial sponsor, should the trialists decide to seek market authorization of the drug.

Conclusions

In theory, evidence from aggregated N-of-1 trials is suitable for use in licensing and reimbursement decisions. The current example illustrates differences in interpretation of N-of-1 results by health authorities. In the era of personalized medicine, consensus is required on the interpretation of data from study designs geared to small groups. Demonstrating effectiveness of inexpensive medicines in small populations may require involvement of non-commercial parties, to preserve affordability.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0636-y) contains supplementary material, which is available to authorized users.

Diversity in mental fatigue and social profile of patients with myasthenia gravis in two different Northern European countries

Self-estimated health can be used for comparison of different diseases between countries. It is important to elaborate on whether disparities in self-estimated health are due to disease-specific parameters or socioeconomic differences. In this study, we aimed at evaluating clinical and social similarities and differences in myasthenia gravis (MG) patients between comparable regions in two Baltic Sea countries, Estonia and Sweden.

METHODS

This cross-sectional study included southern counties in Sweden and Estonia of comparable size. All patients with a confirmed MG diagnosis were asked to answer two questionnaires including demographic and disease-specific data, lifestyle issues, and mental fatigue (Fatigue Severity Scale [FSS]). Clinical fatigue was assessed objectively through the Quantitative Myasthenia Gravis Score (QMG).

RESULTS

Thirty-six of 92 identified patients in Estonia and 40 of 70 identified MG patients in Sweden chose to participate in the study. The demographic characteristics and symptoms reported by the patients were similar. QMG score did not differ; however, the Estonian patients scored their current subjective disease severity significantly higher (5.6 ± 2.8) compared to the Swedish patients (3.4 ± 2.3, p = .0005). Estonian patients also had significantly higher FSS scores (5.0 ± 1.7) than Swedish patients (3.5 ± 1.6; p = .001). Swedish patients were more active and performed physical activity more regularly (29.1% in Estonia and 74.2% in Sweden, p = .004).

CONCLUSIONS

Although, the patients had comparable clinical fatigue, Estonian patients evaluated their health state as being more severe and reported more mental fatigue than Swedish patients. These data indicate large regional differences in disease perception of MG, which is important to consider in international studies.

Thymectomy in Myasthenia Gravis

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

[Thymoma and autoimmune diseases]

The association between thymoma and autoimmunity is well known. Besides myasthenia gravis, which is found in 15 to 20% of patients with thymoma, other autoimmune diseases have been reported: erythroblastopenia, systemic lupus erythematosus, inflammatory myopathies, thyroid disorders, Isaac's syndrome or Good's syndrome. More anecdotally, Morvan's syndrome, limbic encephalitis, other autoimmune cytopenias, autoimmune hepatitis, and bullous skin diseases (pemphigus, lichen) have been reported. Autoimmune diseases occur most often before thymectomy, but they can be discovered at the time of surgery or later. Two situations require the systematic investigation of a thymoma: the occurrence of myasthenia gravis or autoimmune erythroblastopenia. Nevertheless, the late onset of systemic lupus erythematosus or the association of several autoimmune manifestations should lead to look for a thymoma. Neither the characteristics of the patients nor the pathological data can predict the occurrence of an autoimmune disease after thymectomy. Thus, thymectomy usefulness in the course of the autoimmune disease, except myasthenia gravis, has not been demonstrated. This seems to indicate the preponderant role of self-reactive T lymphocytes distributed in the peripheral immune system prior to surgery. Given the high infectious morbidity in patients with thymoma, immunoglobulin replacement therapy should be considered in patients with hypogammaglobulinemia who receive immunosuppressive therapy, even in the absence of prior infection.

Neurologic complications in critically ill pregnant patients

Neurologic complications in a critically ill pregnant woman are uncommon but some of the complications (such as eclampsia) are unique to pregnancy and the puerperal period. Other neurologic complications (such as seizures in the setting of epilepsy) may worsen during pregnancy. Clinical signs and symptoms such as seizure, headache, weakness, focal neurologic deficits, and decreased level of consciousness require careful consideration of potential causes to ensure prompt treatment measures are instituted to prevent ongoing neurologic injury. Clinicians should be familiar with syndromes such as pre-eclampsia, eclampsia, stroke, posterior reversible encephalopathy syndrome, and reversible cerebral vasoconstriction syndrome. Necessary imaging studies can usually be performed safely in pregnancy. Scoring systems for predicting maternal mortality are inadequate, as are recommendations for neurorehabilitation. Tensions can arise when there is conflict between the interests of the mother and the interests of the fetus, but in general maternal health is prioritized. The complexity of care requires a multidisciplinary and multiprofessional approach to achieve best outcome in an often unexpected situation.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

Neuromuscular junction disorders

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

Update on the use of immunoglobulin in human disease: A review of evidence

Human immunoglobulin preparations for intravenous or subcutaneous administration are the cornerstone of treatment in patients with primary immunodeficiency diseases affecting the humoral immune system. Intravenous preparations have a number of important uses in the treatment of other diseases in humans as well, some for which acceptable treatment alternatives do not exist. We provide an update of the evidence-based guideline on immunoglobulin therapy, last published in 2006. Given the potential risks and inherent scarcity of human immunoglobulin, careful consideration of its indications and administration is warranted.

The Effect of Immunonutrition on the Postoperative Complications in Thymoma with Myasthenia Gravis

Object. To test whether preoperative immunonutrition is efficacious in reducing postoperative complications in patients of thymoma with myasthenia gravis (MG). Material and Methods. A total of 244 patients operated on for thymoma with myasthenia gravis were prospectively assigned to two groups, each receiving seven-day preoperative and seven-day postoperative nutrition. The patients in immunonutrition group were given oral immunonutrition (IN). The patients in control group received oral standard nutrition. Immunonutritional and inflammatory biomarkers (IgA, IgG, IgM, CD3t, CD4t, CD8t, CD4t/CD8t ratio, NK-cell, prealbumin, albumin, white blood cells counts, and C-reactive protein) and clinical variables (age, gender, BMI, performance status, type of thymoma, type of MG, operative time, pathology, operative approach, postoperative complications, quantity of drainage, hospital stays) were examined. Results. A significant reduction in the length of hospital stay, quantity of drainage, and postoperative complications was observed in the IN group (p < 0.05). An increase in the level of IgA, IgG, IgM, CD3+T, CD4+T, CD4+T/CD8+T, WBC, CRP, and NK-cell in the IN group was observed after thymectomy, while a decrease was seen with regard to prealbumin and albumin (p < 0.05). Conclusion. Preoperative immunonutrition support is effective in reducing postoperative complications in patients of thymoma with MG. It helps to lower the risk of postoperative infectious complications and hospital stays.

Clinical Features of Neuromuscular Disorders in Patients with N-Type Voltage-Gated Calcium Channel Antibodies

Neuromuscular junction disorders affect the pre- or postsynaptic nerve to muscle transmission due to autoimmune antibodies. Members of the group like myasthenia gravis and Lambert-Eaton syndrome have pathophysiologically distinct characteristics. However, in practice, distinction may be difficult. We present a series of three patients with a myasthenic syndrome, dropped-head syndrome, bulbar and respiratory muscle weakness and positive testing for anti-N-type voltage-gated calcium channel antibodies. In two cases anti-acetylcholin receptor antibodies were elevated, anti-P/Q-type voltage-gated calcium channel antibodies were negative. All patients initially responded to pyridostigmine with a non-response in the course of the disease. While one patient recovered well after treatment with intravenous immunoglobulins, 3,4-diaminopyridine, steroids and later on immunosuppression with mycophenolate mofetil, a second died after restriction of treatment due to unfavorable cancer diagnosis, the third patient declined treatment. Although new antibodies causing neuromuscular disorders were discovered, clinical distinction has not yet been made. Our patients showed features of pre- and postsynaptic myasthenic syndrome as well as severe dropped-head syndrome and bulbar and axial muscle weakness, but only anti-N-type voltage-gated calcium channel antibodies were positive. When administered, one patient benefited from 3,4-diaminopyridine. We suggest that this overlap-syndrome should be considered especially in patients with assumed seronegative myasthenia gravis and lack of improvement under standard therapy.

Clinical features, pathogenesis, and treatment of myasthenia gravis: a supplement to the Guidelines of the German Neurological Society

Myasthenia gravis (MG) is an autoimmune antibody-mediated disorder of neuromuscular synaptic transmission. The clinical hallmark of MG consists of fluctuating fatigability and weakness affecting ocular, bulbar and (proximal) limb skeletal muscle groups. MG may either occur as an autoimmune disease with distinct immunogenetic characteristics or as a paraneoplastic syndrome associated with tumors of the thymus. Impairment of central thymic and peripheral self-tolerance mechanisms in both cases is thought to favor an autoimmune CD4(+) T cell-mediated B cell activation and synthesis of pathogenic high-affinity autoantibodies of either the IgG1 and 3 or IgG4 subclass. These autoantibodies bind to the nicotinic acetylcholine receptor (AchR) itself, or muscle-specific tyrosine-kinase (MuSK), lipoprotein receptor-related protein 4 (LRP4) and agrin involved in clustering of AchRs within the postsynaptic membrane and structural maintenance of the neuromuscular synapse. This results in disturbance of neuromuscular transmission and thus clinical manifestation of the disease. Emphasizing evidence from clinical trials, we provide an updated overview on immunopathogenesis, and derived current and future treatment strategies for MG divided into: (a) symptomatic treatments facilitating neuromuscular transmission, (b) antibody-depleting treatments, and

Acute Neuromuscular Respiratory Failure

PURPOSE OF REVIEW

Neurologists working in the hospital are often called to evaluate patients with severe muscle weakness. Some of these patients can develop ventilatory compromise and require admission to the intensive care unit (ICU). This article reviews the general evaluation of neuromuscular respiratory failure, discusses its differential diagnosis, and provides practical advice on the management of its most common causes.

RECENT FINDINGS

Determining the cause of acute neuromuscular respiratory failure is crucial because functional prognosis is poor in patients for whom the cause cannot be defined. The differential diagnosis is extensive, but the first step is to discriminate between cases related to a primary neurologic disease (primary neuromuscular respiratory failure) and those provoked by systemic disease, most often critical illness from sepsis and multiorgan failure (secondary neuromuscular respiratory failure). Guillain-Barré syndrome (GBS) and myasthenic crisis are the two most frequent causes of primary neuromuscular respiratory failure. Although they are both autoimmune conditions that benefit from the administration of plasma exchange or IV immunoglobulin (IVIg), they are otherwise very different disorders with unique features and distinct complications. Optimal strategies for mechanical ventilation also differ between these two conditions; while myasthenic crisis is ideally managed with noninvasive bilevel positive airway pressure (BiPAP) ventilation, GBS demands early intubation.

SUMMARY

Prompt recognition of neuromuscular respiratory failure can be lifesaving, and identification of its cause has substantial prognostic implications. Adequate management of these patients requires a multidisciplinary team with the neurologist at its center, not only to guide the diagnostic evaluation but often also to prescribe the optimal management.

International consensus guidance for management of myasthenia gravis: Executive summary

Objective:

To develop formal consensus-based guidance for the management of myasthenia gravis (MG).

Methods:

In October 2013, the Myasthenia Gravis Foundation of America appointed a Task Force to develop treatment guidance for MG, and a panel of 15 international experts was convened. The RAND/UCLA appropriateness methodology was used to develop consensus guidance statements. Definitions were developed for goals of treatment, minimal manifestations, remission, ocular MG, impending crisis, crisis, and refractory MG. An in-person panel meeting then determined 7 treatment topics to be addressed. Initial guidance statements were developed from literature summaries. Three rounds of anonymous e-mail votes were used to attain consensus on guidance statements modified on the basis of panel input.

Results:

Guidance statements were developed for symptomatic and immunosuppressive treatments, IV immunoglobulin and plasma exchange, management of impending and manifest myasthenic crisis, thymectomy, juvenile MG, MG associated with antibodies to muscle-specific tyrosine kinase, and MG in pregnancy.

Conclusion:

This is an international formal consensus of MG experts intended to be a guide for clinicians caring for patients with MG worldwide.

Precision medicine in myasthenia graves: begin from the data precision

Myasthenia gravis (MG) is a prototypic autoimmune disease with overt clinical and immunological heterogeneity. The data of MG is far from individually precise now, partially due to the rarity and heterogeneity of this disease. In this review, we provide the basic insights of MG data precision, including onset age, presenting symptoms, generalization, thymus status, pathogenic autoantibodies, muscle involvement, severity and response to treatment based on references and our previous studies. Subgroups and quantitative traits of MG are discussed in the sense of data precision. The role of disease registries and scientific bases of precise analysis are also discussed to ensure better collection and analysis of MG data.

Myasthenia gravis and amyotrophic lateral sclerosis: A pathogenic overlap

The aim was to examine potential joint disease mechanisms for myasthenia gravis (MG) and amyotrophic lateral sclerosis (ALS) through the examination of long-term patient cohorts for comorbidity. Recent studies support early involvement of the neuromuscular junction in ALS patients with subsequent degeneration of motor neurons. Medical records at Haukeland University Hospital from 1987 to 2012 were examined for International Classification of Diseases diagnostic codes for MG and ALS. Sera were re-tested for antibodies to acetylcholine receptor, titin, MuSK and GM1. We report one patient with both MG and ALS, and another 3 patients with suggestive evidence of both conditions. This is far more than expected from prevalence and incidence figures in this area if the disorders were unrelated. Our data suggest that immunological mechanisms in the neuromuscular junction are relevant in ALS pathogenesis. Attention should be given to possible therapeutic targets in the neuromuscular junction and muscle in ALS patients.

Intravenous immunoglobulin in the treatment of neurologic disorders

Intravenous immunoglobulins (IVIGs) are often used in the treatment of autoimmune disorders and immunodeficiencies, and it has been estimated that neurologic indications can account for up to 43% of IVIG used in clinical practice. In neurologic clinical practice, IVIG is used for acute therapy of newly diagnosed autoimmune disorders or exacerbations of pre-existing conditions, or as long-term maintenance treatment for chronic disorders. IVIG exerts its effects on humoral and cell-based immunity through multiple pathways, without a single dominant mechanism. Clinical use of IVIG has been supported by guidelines from American Academy of Neurology and European Federation of Neurologic Societies. IVIG is generally recommended for the treatment of Guillain-Barre syndrome and chronic inflammatory demyelinating polyneuropathy in adults, multifocal motor neuropathy and myasthenia gravis, and should be considered as a treatment option for dermatomyositis in adults and Lambert-Eaton myasthenic syndrome. Additional potential indications include stiff person syndrome, multiple sclerosis during pregnancy or while breastfeeding, refractory autoimmune epilepsy, and paraneoplastic disorders. Clinical use of IVIG is mostly safe but few adverse effects may still occur with potentially severe complications, including aseptic meningitis and thromboembolism. In addition to intravenous route (IVIG), subcutaneous immunoglobulins have been used as an alternative treatment option, especially in patients with limited intravenous access. Treatment with IVIG is effective in various autoimmune diseases, but its broader use is constrained by limited supply. This review evaluates the use of immunoglobulins in treatment of neurologic diseases.

Clinical Significance of Repetitive Compound Muscle Action Potentials in Patients with Myasthenia Gravis: A Predictor for Cholinergic Side Effects of Acetylcholinesterase Inhibitors

Background and Purpose

Acetylcholinesterase inhibitors (AChEIs) are widely used to treat myasthenia gravis (MG). Although AChEIs are usually tolerated well, some MG patients suffer from side effects. Furthermore, a small proportion of MG patients show cholinergic hypersensitivity and cannot tolerate AChEIs. Because repetitive compound muscle action potentials (R-CMAPs) are an electrophysiologic feature of cholinergic neuromuscular hyperactivity, we investigated the clinical characteristics of MG patients with R-CMAPs to identify their clinical usefulness in therapeutic decision-making.

Methods

We retrospectively reviewed the clinical records and electrodiagnostic findings of MG patients who underwent electrodiagnostic studies and diagnostic neostigmine testing (NT).

Results

Among 71 MG patients, 9 could not tolerate oral pyridostigmine bromide (PB) and 17 experienced side effects of PB. R-CMAPs developed in 24 patients after NT. The highest daily dose of PB was lower in the patients with R-CMAPs (240 mg/day vs. 480 mg/day, p<0.001). The frequencies of PB intolerance and side effects were higher in the patients with R-CMAPs than in those without R-CMAPs [37.5% vs. 0% (p<0.001) and 45.8% vs. 12.8% (p=0.002), respectively]. The MG Foundation of America postintervention status did not differ significantly between MG patients with and without R-CMAPs, and the response to immunotherapy was also good in both groups.

Conclusions

Side effects of and intolerance to AChEIs are more common in MG patients with R-CMAPs than in those without R-CMAPs. AChEIs should be used carefully in MG patients with R-CMAPs. The presence of R-CMAPs after NT may be a good indicator of the risks of PB side effects and intolerance.

Current and future immunotherapy targets in autoimmune neurology

Randomized controlled treatment trials of autoimmune neurologic disorders are generally lacking and data pertaining to treatment are mostly derived from expert opinion, large case series, and anecdotal reports. The treatment of autoimmune neurologic disorders comprises oncologic therapy (where appropriate) and immunotherapy. In this chapter, we first describe the standard acute and chronic immunotherapies and provide a practical overview of their use in the clinic (mechanisms of action, dosing, monitoring, and side effects). Novel approaches to treatment of autoimmune neurologic disorders, through new drug discovery or repurposing, are dependent on improved mechanistic understanding of immunopathology. Such approaches, with emphasis on monoclonal antibodies, are discussed using the paradigm of three autoimmune neurologic disorders whose immunopathogenesis is better understood, specifically myasthenia gravis, neuromyelitis optica, and chronic inflammatory demyelinating polyradiculoneuropathy. It is important to realize that the treatment strategy and management plan must be individualized for each patient. In general these are influenced by the following: clinical severity, antibody type, presence or absence of cancer, and prior treatment response, if known.

Long-term observation of incremental response and antibodies to voltage-gated calcium channels in patients with Lambert–Eaton myasthenic syndrome: two case reports

Introduction

Lambert–Eaton myasthenic syndrome is a rare autoimmune disorder of neuromuscular transmission due to the presence of antibodies to presynaptic P/Q-type voltage-gated calcium channels. The gold standard of therapy is the potassium channel blocker 3,4-diaminopyridine. To the best of our knowledge, no clinical reports have been published to date about long-term follow-up outcomes in patients who discontinued 3,4-diaminopyridine therapy. In addition, we know of no recent articles in which the natural history in patients with autoimmune-mediated Lambert–Eaton myasthenic syndrome has been addressed. In this report, we describe the cases of two such patients.

Case presentation

Patient 1 was a Caucasian man who had been diagnosed at age 15 years with Lambert–Eaton myasthenic syndrome with symptoms of fluctuating muscle weakness and easy fatigability. These symptoms stabilized, and his electrophysiological parameters normalized, during treatment with a maintenance dose of 50mg/day of 3,4-diaminopyridine. After 5.5 years, however, he wished to discontinue the treatment. After that point, his electrophysiological parameters and presynaptic P/Q-type voltage-gated calcium-channel antibody titer remained stable. During the 15-year follow-up period, patient 1 reported mild exertion-induced complaints but did not feel restricted in his occupation and most daily activities. Patient 2 was a Caucasian man diagnosed at 32 years of age with a moderate limb girdle syndrome. He was treated with up to 80mg/day of 3,4-diaminopyridine. Because of the drug’s very short-lasting effect (<1 hour), however, he took it mostly irregularly (≤1×20mg/day). During the 14- year period of observation, his repetitive nerve stimulation responses and presynaptic P/Q-type voltage-gated calcium-channel antibody titer remained stable, his compound muscle action potential amplitudes were decreasing and his clinical symptoms did not deteriorate. At his last follow-up examination, patient 2 was independent in all of his daily activities.

Conclusion

Some patients with autoimmune-mediated Lambert–Eaton myasthenic syndrome show a stable clinical long-term course without treatment. The benefit of each long-term therapy should be critically assessed during follow-up, and possible side effects should be balanced against the quality of life in these patients.

The European LEMS Registry: Baseline Demographics and Treatment Approaches

Introduction

Lambert–Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder affecting the neuromuscular junction, clinically characterized by proximal muscle weakness and autonomic changes. LEMS is often associated with an underlying tumor (paraneoplastic form) but also occurs in the absence of cancer (idiopathic form). Treatment consists of immunomodulation (immunosuppression), anticancer treatment when carcinoma is present, and symptomatic treatment [acetylcholinesterase inhibitors and potassium channel blockers, e.g., amifampridine (3,4-diaminopyridine, i.e., 3,4-DAP), to improve neurotransmission]. Although there has long been information from case reports, several randomized controlled trials, and treatment guidelines, population data are still scarce.

Methods

The LEMS patient registry was launched in the European community in mid-2010 as a voluntary, multinational, observational, non-interventional program to collect structured empirical data on clinical course, treatment utilization, and safety and efficacy from the use of LEMS-specific treatments.

Results

Sixty-nine patients have been enrolled [36 males, 32 females, 1 gender not reported; mean age 61.5 (27–84) years]. Eighteen patients (26%) were diagnosed with an associated carcinoma. At the time of enrollment, the majority of patients (65%) were receiving amifampridine [either compounded 3,4-DAP (22%) or 3,4-DAP phosphate, Firdapse^® (43%)]. At enrollment, most patients demonstrate a profile of mild-to-moderate deficits in daily functioning but generally have good muscle strength, albeit with reduced deep tendon reflexes, frequent ataxia during walking, and signs of autonomic dysfunction including dry mouth, bladder dysfunction, and constipation.

Conclusion

The LEMS European Union registry will continue to enroll patients and periodically report the accrued longitudinal data obtained on clinical assessments and laboratory findings, treatment practices, the safety and efficacy of treatment approaches, and long-term clinical outcomes.

Funding

BioMarin Pharmaceutical Inc., Novato, CA, USA.

Electronic supplementary material

The online version of this article (doi:10.1007/s40120-015-0034-0) contains supplementary material, which is available to authorized users.

Nonmelanoma skin cancer risk awareness in azathioprine-treated myasthenia gravis patients

OBJECTIVES

Increased rates of NMSC (nonmelanoma skin cancer) have recently been reported in people with MG (myasthenia gravis) receiving azathioprine treatment. Guidelines on azathioprine for patients with dermatological and gastrointestinal disorders stress the importance of NMSC risk awareness and prevention. The aim of this study is to assess whether MG patients are being informed of this risk.

METHODS

Clinical records of patients with MG attending a university hospital neurology clinic were reviewed. Data on patient demographics, clinical presentation, diagnostic tests, azathioprine treatment, development of NMSC, and counseling regarding NMSC risk were recorded.

RESULTS

Sixty-nine MG cases were identified, median age 58 years (range 20-90). Forty-two (60.9%) had received azathioprine at some point with a mean cumulative dose of 235.5 g (range 9.1-972.8 g). Skin cancer risk and prevention advice provision was documented in 3 (7.1%) azathioprine-treated patients. Five patients developed histologically confirmed NMSC of whom all were treated with azathioprine (incidence rate of 24.9 per 1000, 16 times higher than expected). Documented advice on other safety issues such as regular blood test monitoring was found in 33 (78.8%) azathioprine-treated cases.

CONCLUSIONS

Preventative measures such as daily sunscreen use have been shown to reduce the incidence of NMSC in the general population. The results of this study demonstrate a very low rate of advice provision about NMSC risk in azathioprine-treated MG patients and the need for increased awareness among treating neurologists and patients.

Immune Globulin Intravenous: Myasthenia Gravis (Acute Exacerbation)

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to jgeneral@ku.edu .

[Intravenous immunoglobulin in treatment of autoimmune neurological diseases in children]

Though the mechanisms of action of intravenous immunoglobulins (IVIG) are not completely understood, these drugs are widely used in treatment of autoimmune diseases. In this review, we have analyzed the literature on the use of IVIG in the treatment of autoimmune diseases of the nervous system in children and discuss the management of patients basing on the recommendation of the European Federation of Neurological Societies. The efficacy of IVIG in children has been shown as first line treatment in Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, dermatomyositis as a second-line drug in the combination with prednisolone or immunosuppressors in patients refractory to treatment with corticosteroids and cytostatics, myasthenic crisis in myasthenia gravis, exacerbations and short-term treatment of severe forms, non-responsiveness to acetylcholinesterase inhibitors, multiple sclerosis as second or third line of treatment in patients with relapsing-remitting course with intolerance to standard immunomodulatory therapy, acute multiple encephalomyelitis with no response to the treatment with high doses of corticosteroids, paraneoplastic syndromes, pharmacoresistant epilepsy and autoimmune encephalitis. Because the right choice of the drug plays a key role, in particular, in children, that determines the efficacy and safety of the treatment, we present the main approaches to the choice of the drug and schemes of treatment of autoimmune diseases of the nervous system in children.