Italian recommendations for the diagnosis and treatment of myasthenia gravis

The changing landscape of autoantibody testing in myasthenia gravis in the setting of novel drug treatments

Acquired myasthenia gravis (MG) is an autoimmune disease targeting the specific proteins in the postsynaptic muscle membrane. 50% of ocular and 80% of generalized MG have acetylcholine receptor antibodies (AChR Abs). 1-10% of MG patients have antibodies against muscle-specific kinase (MuSK), and 2-50 % of seronegative MG cases have antibodies against lipoprotein-receptor-related protein4 antibodies (LRP4 Abs). Serological testing is crucial for diagnosing and determining the appropriate therapeutic approach for MG patients. The radioimmunoprecipitation assay (RIPA) method is a historical standard test for detecting the AChR Abs and MuSK Abs. While it has nearly 100% specificity in the AChR Abs detection, its sensitivity is between 50--92%. The sensitivity and specificity of RIPA for detecting MuSK Abs is much lower. The fixed and live Cell-Based assays (f-CBA and L- CBA) have higher sensitivity than RIPA. With advancements in the serological diagnosis and management of MG, we now recommend a complete reflex testing algorithm on the first pretreatment sample of a suspected MG patient, starting with the binding and blocking assays for AChR Abs by RIPA and/ or f-CBA. If AChR Ab is negative, then reflex to MuSK Abs by RIPA and/ or CBAs. If AChR and MuSK Abs are negative, then use clustered L-CBA by request.

Comorbidity in myasthenia gravis: multicentric, hospital-based, and controlled study of 178 Italian patients

BACKGROUND

Myasthenia gravis (MG) is an autoimmune disorder with fluctuating weakness that causes significant disability and morbidity. Comorbidities may influence the course of MG, particularly in specific subgroups. The aim of this study is to investigate the frequency of comorbidities in MG patients compared to healthy controls (HC) and to evaluate their distribution according to age at disease onset, sex, and disease severity.

METHODS

MG patients attending the University Hospital "Paolo Giaccone" in Palermo and "SS Annunziata" Hospital in Chieti were enrolled; HC were enrolled from the general population. Non-parametric statistics and logistic regression were used to assess the association of specific comorbidities according to age at disease onset, sex, disease subtypes, and severity of the disease.

RESULTS

A total of 356 subjects were included in the study: 178 MG patients (46% F; median age 60 years [51-71]) and 178 sex- and age-matched HC (46% F, median age 59 years [50-66]). Overall, 86% of MG patients and 76% of HC suffered from comorbidities, and MG patients had a higher number of comorbidities compared to HC. Patients with late-onset suffered from more comorbidities than those with early-onset MG. Hypertension was more common in male patients with MG, while thymic hyperplasia, osteoporosis, and autoimmune diseases were more common in females. Respiratory disorders and thymoma were more common in patients with more severe disease (p < 0.05 for all comparisons).

CONCLUSION

MG patients, particularly those with late onset, showed a higher prevalence of comorbidities than HC. Assessment of comorbidities in MG is an essential issue to identify the appropriate treatment and achieve the best management.

Acetylcholinesterase inhibitors are ineffective in MuSK-antibody positive myasthenia gravis: Results of a study on 202 patients

BACKGROUND

Myasthenia gravis (MG) with MuSK antibodies (MuSK-MG) represents a distinct subtype with different responses to treatments compared to patients with AChR antibodies, especially in terms of tolerance to acetylcholinesterase inhibitors (AChEI). However, AChEI are often used as first line symptomatic treatment in MuSK-MG, despite reports that they are poorly tolerated, seldom effective or even deleterious.

METHODS

We analyzed demographic, clinical and therapeutic responses and side-effects in the large cohort of 202 MuSK-MG patients cared for at the MG Clinic of Azienda Ospedaliero-Universitaria Pisana.

RESULTS

165 patients had received AChEI at first evaluation. Only 7/165 patients (4.2%) reported an initial clinical benefit. Conversely, 76.9% of patients reported at least one side effect, most commonly neuromuscular hyperexcitability (68.4%), gastrointestinal (53.9%) and neurovegetative (35.8%) disturbances. 56 (33.9%) patients reported a concomitant worsening of muscle weakness and twelve patients (7.3%) suffered a cholinergic crisis. According to these patients, the severity of cholinergic side effects was greater at higher doses of AChEI, but side effects occurred regardless of the dose administered and ceased once the drug was discontinued.

CONCLUSIONS

This is the largest population of MuSK-MG patients reported for perceived responsiveness and tolerance to AChEI treatment. Our obervations strongly suggest avoiding this treatment in MuSK-MG.

Targeting autoimmune mechanisms by precision medicine in Myasthenia Gravis

Myasthenia Gravis (MG) is a chronic disabling autoimmune disease caused by autoantibodies to the neuromuscular junction (NMJ), characterized clinically by fluctuating weakness and early fatigability of ocular, skeletal and bulbar muscles. Despite being commonly considered a prototypic autoimmune disorder, MG is a complex and heterogeneous condition, presenting with variable clinical phenotypes, likely due to distinct pathophysiological settings related with different immunoreactivities, symptoms' distribution, disease severity, age at onset, thymic histopathology and response to therapies. Current treatment of MG based on international consensus guidelines allows to effectively control symptoms, but most patients do not reach complete stable remission and require life-long immunosuppressive (IS) therapies. Moreover, a proportion of them is refractory to conventional IS treatment, highlighting the need for more specific and tailored strategies. Precision medicine is a new frontier of medicine that promises to greatly increase therapeutic success in several diseases, including autoimmune conditions. In MG, B cell activation, antibody recycling and NMJ damage by the complement system are crucial mechanisms, and their targeting by innovative biological drugs has been proven to be effective and safe in clinical trials. The switch from conventional IS to novel precision medicine approaches based on these drugs could prospectively and significantly improve MG care. In this review, we provide an overview of key immunopathogenetic processes underlying MG, and discuss on emerging biological drugs targeting them. We also discuss on future direction of research to address the need for patients' stratification in endotypes according with genetic and molecular biomarkers for successful clinical decision making within precision medicine workflow.

Myasthenia gravis: the changing treatment landscape in the era of molecular therapies

Myasthenia gravis (MG) is an autoimmune disorder that affects the neuromuscular junction, leading to muscle weakness and fatigue. MG is caused by antibodies against the acetylcholine receptor (AChR), the muscle-specific kinase (MuSK) or other AChR-related proteins that are expressed in the postsynaptic muscle membrane. The standard therapeutic approach for MG has relied on acetylcholinesterase inhibitors, corticosteroids and immunosuppressants, which have shown good efficacy in improving MG-related symptoms in most people with the disease; however, these therapies can carry a considerable burden of long-term adverse effects. Moreover, up to 15% of individuals with MG exhibit limited or no response to these standard therapies. The emergence of molecular therapies, including monoclonal antibodies, B cell-depleting agents and chimeric antigen receptor T cell-based therapies, has the potential to revolutionize the MG treatment landscape. This Review provides a comprehensive overview of the progress achieved in molecular therapies for MG associated with AChR antibodies and MuSK antibodies, elucidating both the challenges and the opportunities these therapies present to the field. The latest developments in MG treatment are described, exploring the potential for personalized medicine approaches.

Depression: A Contributing Factor to the Clinical Course in Myasthenia Gravis Patients

Background and Objectives: The association between myasthenia gravis (MG) and depression is intricate and characterized by bidirectional causality. In this regard, MG can be a contributing factor to depression and, conversely, depression may worsen the symptoms of MG. This study aimed to identify any differences in the progression of the disease among patients with MG who were also diagnosed with depression as compared to those without depression. Our hypothesis focused on the theory that patients with more severe MG symptoms may have a higher likelihood of suffering depression at the same time. Materials and Methods: One hundred twenty-two male and female patients (N = 122) aged over 18 with a confirmed diagnosis of autoimmune MG who were admitted to the Neurology II department of Myasthenia Gravis, Clinical Institute Fundeni in Bucharest between January 2019 and December 2020, were included in the study. Patients were assessed at baseline and after six months. The psychiatric assessment of the patients included the Hamilton Depression Rating Scale-17 items (HAM-D), and neurological status was determined with two outcome measures: Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis Activities of Daily Life (MG-ADL). The patients were divided into two distinct groups as follows: group MG w/dep, which comprised 49 MG patients diagnosed with depressive disorder who were also currently receiving antidepressant medication, and group MG w/o dep, which consisted of 73 patients who did not have depression. Results: In our study, 40.16% of the myasthenia gravis (MG) patients exhibited a comorbid diagnosis of depression. Among the MG patients receiving antidepressant treatment, baseline assessments revealed a mean MG-ADL score of 7.73 (SD = 5.05), an average QMG score of 18.40 (SD = 8.61), and a mean Ham-D score of 21.53 (SD = 7.49). After a six-month period, a statistically significant decrease was observed in the MG-ADL (2.92, SD = 1.82), QMG (7.15, SD = 4.46), and Ham-D scores (11.16, SD = 7.49) (p < 0.0001). These results suggest a significant correlation between MG severity and elevated HAM-D depression scores. Regarding the MG treatment in the group with depression, at baseline, the mean dose of oral corticosteroids was 45.10 mg (SD = 16.60). Regarding the treatment with pyridostigmine, patients with depression and undergoing antidepressant treatment remained with an increased need for pyridostigmine, 144.49 mg (SD = 51.84), compared to those in the group without depression, 107.67 mg (SD = 55.64, p < 0.001). Conclusions: Our investigation confirms that the occurrence of depressive symptoms is significantly widespread among individuals diagnosed with MG. Disease severity, along with younger age and higher doses of cortisone, is a significant factor associated with depression in patients with MG. Substantial reductions in MG-ADL and QMG scores were observed within each group after six months, highlighting the effectiveness of MG management. The findings suggest that addressing depressive symptoms in MG patients, in addition to standard MG management, can lead to improved clinical outcomes.

A multicentre, prospective, double-blind study comparing the accuracy of autoantibody diagnostic assays in myasthenia gravis: the SCREAM study

BACKGROUND

Laboratory determination of autoantibodies against acetylcholine receptor (AChR), muscle-specific kinase (MuSK) and other autoantigens have been integrated into the diagnosis of myasthenia gravis (MG). However, evidence supporting the selection of methodologies is lacking.

METHODS

In this prospective, multicentre cohort study, we recruited patients with suspected MG to evaluate the diagnostic accuracy of cell-based assay (CBA), radioimmunoprecipitation assay (RIPA) and enzyme-linked immunosorbent assay (ELISA) in detecting AChR and MuSK autoantibodies. This study is registered with www.clinicaltrials.gov, number NCT05219097.

FINDINGS

2272 eligible participants were recruited, including 2043 MG, 229 non-MG subjects. AChR antibodies were detected in 1478, 1310, and 1280 out of a total of 2043 MG patients by CBA, RIPA, and ELISA, respectively; sensitivity, 72.3% (95% CI, 70.3-74.3), 64.1% (95% CI, 62.0-66.2), 62.7% (95% CI, 60.5-64.8); specificity, 97.8% (95% CI, 95.0-99.3), 97.8% (95% CI, 95.0-99.3), 94.8% (95% CI, 91.9-97.7). MuSK antibodies were found in 59, 50, and 54 from 2043 MG patients by CBA, RIPA and ELISA, respectively; sensitivity, 2.9% (95% CI, 2.2-3.7), 2.4% (95% CI, 1.8-3.2), 2.6% (95% CI, 2.0-3.4); specificity, 100% (95% CI, 98.4-100), 100% (95% CI, 98.4-100), and 99.1% (95% CI, 96.9-99.9). The area under the curve of AChR antibodies tested by CBA was 0.858, and there were statistical differences with RIPA (0.843; p = 0.03) and ELISA (0.809; p < 0.0001).

INTERPRETATION

CBA has a higher diagnostic accuracy compared to RIPA or ELISA in detecting AChR and MuSK autoantibodies for MG diagnosis.

FUNDING

New Terrain Biotechnology, Inc., Tianjin, China.

Detection of Antibodies against the Acetylcholine Receptor in Patients with Myasthenia Gravis: A Comparison of Two Enzyme Immunoassays and a Fixed Cell-Based Assay

The detection of serum anti-acetylcholine receptor (AChR) antibodies is currently an important tool for diagnosing myasthenia gravis (MG) since they are present in about 85% of MG patients. Many serological tests are now available. Nevertheless, results from these tests can be different in some patients. The aim of this study is to compare the sensitivity of a commercially available fixed cell-based assay (F-CBA) to that of enzyme-linked immunosorbent assay (ELISA) kits for anti-AChR detection in patients with a diagnosis of MG. Overall, 143 patients with a confirmed MG diagnosis were included in the study. The detection and measurement of serum anti-AChR antibodies were performed by three analytical methods, namely, a competitive ELISA (cELISA), an indirect ELISA (iELISA), and an F-CBA, according to the manufacturers' instructions. Anti-AChR antibody titers were positive in 94/143 (66%) using the cELISA, in 75/143 (52%) using the iELISA and in 61/143 (43%) using the F-CBA (adult and/or fetal). Method agreement, evaluated by concordant pairs and Cohen's kappa, was as follows: cELISA-iELISA: 110/143 (77%), k = 0.53 (95%CI 0.40-0.66); cELISA-F-CBA: 108/143 (76%), k = 0.53 (95%CI 0.41-0.66); iELISA-F-CBA: 121/143 (85%), k = 0.70 (95%CI 0.57-0.80). Our findings show that the cELISA has better analytical performance than the iELISA and F-CBA. However, the iELISA and F-CBA show the highest concordance.

Real world study on prevalence, treatment and economic burden of myasthenia gravis in Italy

The purpose of this study was to investigate the epidemiology, management, and economic burden of myasthenia gravis in settings of real clinical practice. The analysis used administrative databases covering around 12 million subjects across Italy and included all adult patients with hospitalization discharge diagnosis or active exemption code for myasthenia gravis or with ≥1 pyridostigmine prescription from 2011 to 2018. The estimated prevalence of myasthenia gravis during 2018 was in the range 13.5-29.3/100,000 people (depending on the criteria applied), corresponding to 8190-17,728 alive patients, when reproportioning data to the entire Italian population. Overall 4397 patients with myasthenia gravis (mean age 61.7 years, 46.6% males) were included. A large pyridostigmine use was observed (84.0%-46.8% from 1st to 3rd year of follow-up), followed by corticosteroids (54.5%-44.6% from 1st to 3rd year of follow-up) and non-steroidal immunosuppressants (16% over follow-up). Total direct healthcare costs for myasthenia gravis were 4-times higher than those of the general population (€3771 and €869, respectively), and up to 9-fold increased when considering patients with exacerbation (€7827). These findings showed the epidemiologic burden of myasthenia gravis and the complexity of the therapeutic management for the affected patients, with large use of treatments and elevated healthcare expenditures.

Iron metabolism in non-anemic myasthenia gravis patients: A cohort study

BACKGROUND

The association of iron metabolism parameters with disease severity and outcome in myasthenia gravis (MG) patients has not been reported. This study was conducted to determined clinical factors including iron metabolism parameters correlated with disease severity and future outcome in non-anemic immunotherapy-naïve MG patients first receiving immunotherapy.

MATERIAL AND METHODS

One hundred and ten patients were included at baseline to explore predictor variables associated with disease severity represented by variables derived from MG activities of daily living (MG-ADL) score using multivariate logistic regression, after which 103 and 98 patients were included respectively in multivariate survival analyses at 6-month and 12-month follow-up to identify predictors for minimal manifestation status (MMS) after starting immunotherapy.

RESULTS

Higher ferritin level was independently associated with higher risk of severe generalized disease in non-anemic immunotherapy-naïve MG patients. Total iron binding capacity <250 μg/dL and the interval between onset and immunotherapy <1 year were independent predictors for MMS at 6-month and 12-month follow-up after initiating immunotherapy. Transferrin <2.00 g/L was an independent predictor for MMS at 12-month follow-up.

CONCLUSION

Iron metabolism parameters might be promising biomarkers for evaluating disease severity and guiding therapeutic decision in MG patients.

Role of autoantibody levels as biomarkers in the management of patients with myasthenia gravis: A systematic review and expert appraisal

BACKGROUND AND PURPOSE

Although myasthenia gravis (MG) is recognized as an immunoglobulin G autoantibody-mediated disease, the relationship between autoantibody levels and disease activity in MG is unclear. We sought to evaluate this landscape through systematically assessing the evidence, testing the impact of predefined variables on any relationship, and augmenting with expert opinion.

METHODS

In October 2020, a forum of leading clinicians and researchers in neurology from across Europe (Expert Forum for Rare Autoantibodies in Neurology in Myasthenia Gravis) participated in a series of virtual meetings that took place alongside the conduct of a systematic literature review (SLR).

RESULTS

Forty-two studies were identified meeting inclusion criteria. Of these, 10 reported some correlation between a patient's autoantibody level and disease severity. Generally, decreased autoantibody levels (acetylcholine receptor, muscle-specific kinase, and titin) were positively and significantly correlated with improvements in disease severity (Quantitative Myasthenia Gravis score, Myasthenia Gravis Composite score, Myasthenia Gravis Activities of Daily Living score, Myasthenia Gravis Foundation of America classification). Given the limited evidence, testing the impact of predefined variables was not feasible.

CONCLUSIONS

This first SLR to assess whether a correlation exists between autoantibody levels and disease activity in patients with MG has indicated a potential positive correlation, which could have clinical implications in guiding treatment decisions. However, in light of the limited and variable evidence, we cannot currently recommend routine clinical use of autoantibody level testing in this context. For now, patient's characteristics, clinical disease course, and laboratory data (e.g., autoantibody status, thymus histology) should inform management, alongside patient-reported outcomes. We highlight the need for future studies to reach more definitive conclusions on this relationship.

Comparative the efficacy and acceptability of immunosuppressive agents for myasthenia gravis: A protocol for systematic review and network meta-analysis

BACKGROUND

Immunosuppressive drugs are routinely used to treat myasthenia gravis (MG). However, current recommendations provide limited evidence to support treatment options, leading to considerable variation in practice among healthcare specialists. Hence, we present a protocol for a systematic review and network meta-analysis (NMA) to update the evidence by comparing the efficacy and acceptability of oral immunosuppressive drugs for the treatment of MG.

METHODS

We will conduct a systematic review and NMA of all randomized controlled trials evaluating the following oral immunosuppressive drugs for the treatment of MG. Published studies will be searched using the following databases from inception to November 23, 2021: CENTRAL, the CINAHL, MEDLINE, Embase, PsycINFO, Web of Science, and 3 Chinese databases (Chinese Biomedical Literatures Database, CNKI, and Wan Fang database). Assessment of study eligibility and data extraction will be conducted independently by 2 reviewers. The main outcome will be a quantitative MG scoring system. We will conduct Bayesian NMA to synthesize all evidence for each outcome and obtain a comprehensive ranking of all treatments. The quality of the evidence will be evaluated using the Grading of Recommendations, Assessment, Development, and Evaluations framework.

RESULTS

The objective of this study was to assess the relative clinical efficacy and acceptability of first-line immunosuppressants for the treatment of MG, using a systematic review and NMA approach.

CONCLUSION

In the absence of head-to-head trials comparing therapies, evidence from this NMA of available clinical trials will inform clinicians, patients, and families the risk-benefit profiles of different treatment options.

Diagnosis and Management of Myasthenia Gravis

PURPOSE OF REVIEW

This article reviews updated diagnostic procedures and currently available treatment modalities for myasthenia gravis (MG).

RECENT FINDINGS

Patients with MG can be classified based on antibody status and their clinical presentation; treatment responses may differ based on disease subtypes. Improved diagnostic methods and recognition of new antigenic targets such as lipoprotein-related protein 4 have led to improved diagnostic efficiencies. Corticosteroids remain the first-line immunotherapy, but there is a trend toward minimizing their use at high doses and for long durations. Oral immunosuppressants such as mycophenolate mofetil, azathioprine, and tacrolimus remain useful. An international, multicenter randomized trial comparing thymectomy plus prednisone with prednisone alone demonstrated that thymectomy improves clinical outcomes in selected patients with nonthymomatous MG. Eculizumab, efgartigimod, and ravulizumab have recently been approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive. These drugs take advantage of novel mechanisms of action and expand treatment options for patients with MG. Data on rituximab suggest that it can be a good option, especially for patients with MG who are positive for antibodies against muscle-specific tyrosine kinase (MuSK). The number of clinical trials and drugs in development for MG is steadily increasing.

SUMMARY

The diagnosis of MG can generally be made from the patient's history, a neurologic examination, and laboratory and electrodiagnostic testing. Carefully selected treatment improves outcomes in MG. Additional treatment options for MG will likely be available in the near future.

Iron metabolism patterns in non-anemic patients with myasthenia gravis: A cross-sectional and follow-up study

Background and purpose

Iron metabolism in myasthenia gravis (MG) and factors associated with it are explored by few published studies. Therefore, this study aimed to compare iron metabolism patterns between patients with MG and healthy individuals as well as between the same group of patients before and after immunotherapy, and to identify predictors of iron metabolism disorders in MG.

Materials and methods

For this study, 105 patients and healthy individuals were included at baseline, after which paired parametric and non-parametric tests were adopted to compare their iron metabolism patterns, and multivariate binary logistic regression was used to identify predictors of iron metabolism disorders. Patients with MG were then followed up for 12 ± 3 months to explore alterations in their iron metabolism patterns after starting immunotherapy with the help of paired tests.

Results

Non-anemic immunotherapy-naive patients with MG had significantly lower serum iron (SI) and transferrin saturation (TS) levels than healthy individuals. Premenopausal female was significantly associated with SI < 65 μg/dL and iron deficiency in these patients. However, iron metabolism parameters did not significantly alter after around 12 months of immunotherapy in patients with MG.

Conclusion

Iron inadequacy was present in patients with MG, particularly premenopausal female patients, and it would hardly improve after immunotherapy. Given the significant role of iron in human body, it should be given more attention in patients with MG.

miRNAs as the important regulators of myasthenia gravis: involvement of major cytokines and immune cells

Myasthenia gravis (MG) is a type of muscle paralysis created by immune responses against acetylcholine receptor proteins in neuromuscular synapses. This disease is characterized by muscle weakness, especially ocular weakness symptoms that could be ptosis (fall of the upper eyelid) or diplopia (double vision of a single object). Some patients also identified with speech and swallowing problems. The main goals of MG therapeutic approaches are to achieve remission, reduce symptoms, and improve life quality. Recently, other studies have revealed the potential role of various microRNAs (miRNAs) in the development of MG through different mechanisms and have proposed these molecules as effective biomarkers for the treatment of MG. This review was aimed at providing an overview of the critical regulatory roles of various miRNAs in the pathogenesis of this autoimmune disease focusing on human MG studies and the interaction between different miRNAs with important cytokines and immune cells during the development of this autoimmune disease.

Impact of COVID-19 in AChR Myasthenia Gravis and the Safety of Vaccines: Data from an Italian Cohort

Background and aims. Patients with Myasthenia gravis (MG) are considered vulnerable as they may present with respiratory muscle weakness and because they are on immunosuppressive treatment; thereby, COVID-19 may have a detrimental effect on these patients. Vaccines against COVID-19 are currently available and it has been shown as they can prevent severe COVID-19 in vulnerable patients. Notwithstanding their efficacy, vaccine hesitancy has not been completely dispelled in the general population. Unfortunately, there is limited data about the safety of these vaccines in MG patients. The aims of this study are to evaluate the impact of COVID-19 in a MG cohort, the adherence to COVID-19 vaccination in Italy and vaccine safety in MG patients. Methods. A retrospective cohort study of MG patients attending the Neuromuscular Clinic of the University Hospital “Paolo Giaccone” of Palermo, Italy, was performed. Patients underwent telephone interviews with a dedicated questionnaire on SARS-CoV-2 vaccination and infection. Vaccine safety was assessed though the evaluation of vaccine-related adverse events (AEs) and comparisons of MG-ADL scores before and after vaccination. Patient worsening was defined as two or more point increases in MG-ADL scores. Results. From a total of 90 participants, 75 answered the questionnaire and 70.5% of them (n = 53) received the vaccine; ten patients did not receive vaccination and 3 patients were partially vaccinated. Among the vaccinated patients, about 45% (n = 24) experienced at least one AE, with a complete resolution within one week. No serious AEs and life-threatening conditions were observed. Globally, MG-ADL scores did not worsen after vaccination. Nine unvaccinated patients experienced SARS-CoV2 infection and four of them (44%) died—one patient required respiratory support, whereas three patients were asymptomatic. Conclusions. COVID-19 significantly impacted MG patients with an increase in mortality due to respiratory sequelae. Vaccines against SARS-CoV-2 showed good short-term safety in MG patients, who may take advantage of vaccination to avoiding life-threatening complications such as COVID-19 pneumonia.

Motor neuron, peripheral nerve, and neuromuscular junction disorders

In amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome (GBS), and neuromuscular junction disorders, three mechanisms may lead, singly or together, to respiratory emergencies and increase the disease burden and mortality: (i) reduced strength of diaphragm and accessory muscles; (ii) oropharyngeal dysfunction with possible aspiration of saliva/bronchial secretions/drink/food; and (iii) inefficient cough due to weakness of abdominal muscles. Breathing deficits may occur at onset or more often along the chronic course of the disease. Symptoms and signs are dyspnea on minor exertion, orthopnea, nocturnal awakenings, excessive daytime sleepiness, fatigue, morning headache, poor concentration, and difficulty in clearing bronchial secretions. The "20/30/40 rule" has been proposed to early identify GBS patients at risk for respiratory failure. The mechanical in-exsufflator is a device that assists ALS patients in clearing bronchial secretions. Noninvasive ventilation is a safe and helpful support, especially in ALS, but has some contraindications. Myasthenic crisis is a clinical challenge and is associated with substantial morbidity including prolonged mechanical ventilation and 5%-12% mortality. Emergency room physicians and consultant pulmonologists and neurologists must know such respiratory risks, be able to recognize early signs, and treat properly.

Vaccination in pediatric acquired inflammatory immune-mediated neuromuscular disorders

AIM

To analyse literature data on vaccine related induction, worsening of the disease and disease reccurrences as well as vaccine safety and efficacy among pediatric patients with acquired inflammatory immune-mediated neuromuscular disorders (NMD).

METHODS

Medline, Pub Med and Scopus database search from 1975 to 2020 focused on pediatric age was conducted including peer reviews, meta analyses and epidemiological studies on vaccination and Guillain-Barré syndrome (GBS), Bell's palsy, optic neuritis (ON), myasthenia gravis (MG), chronic inflammatory demyelinating polyneuropathy (CIDP) and immune-mediated inflammatory myopathy (IM).

RESULTS AND CONCLUSION

s: There are no strong evidence supporting relationship between vaccination with different pediatric vaccines and development of first episodes or reccurrences of GBS, Bell's palsy, optic neuritis (ON), juvenile MG, CIDP, and IM. The vaccination and revaccination with inactivated vaccines is considered safe in children with medical history of GBS, Bell's palsy, ON, MG and IM. Caution when immunization against influenza, quadrivalent conjugated meningococcal vaccine (MCV4) and pneumococcal disease and avoiding tetanus toxoid immunization in CIDP patients is suggested. Patients with immune mediated acquired NMD should be vaccinated with live vaccines before the initiation of immunosupressive treatment. Immunosuppressed patients with low protective antibody titers should be considered for revaccination.

Patients With Myasthenia Gravis With Acute Onset of Dyspnea: Predictors of Progression to Myasthenic Crisis and Prognosis

Background: Life-threatening myasthenic crisis (MC) occurs in 10–20% of the patients with myasthenia gravis (MG). It is important to identify the predictors of progression to MC and prognosis in the patients with MG with acute exacerbations.

Objective: This study aimed to explore the predictors of progression to MC in the patients with MG with acute onset of dyspnea and their short-term and long-term prognosis.

Methods: This study is a retrospective cohort study. We collected and analyzed data on all the patients with MG with acute dyspnea over a 10-year period in a single center using the univariate and multivariate analysis.

Results: Eighty-six patients with MG were included. In their first acute dyspnea episodes, 36 (41.9%) episodes eventually progressed to MC. A multivariate analysis showed that the early-onset MG (adjusted OR: 3.079, 95% CI 1.052–9.012) and respiratory infection as a trigger (adjusted OR: 3.926, 95% CI 1.141–13.510) were independent risk factors for the progression to MC, while intravenous immunoglobulin (IVIg) treatment prior to the mechanical ventilation (adjusted OR: 0.253, 95% CI 0.087–0.732) was a protective factor. The prognosis did not significantly differ between the patients with and without MC during the MG course, with a total of 45 (52.3%) patients reaching post-intervention status better than minimal manifestations at the last follow-up.

Conclusion: When treating the patients with MG with acute dyspnea, the clinicians should be aware of the risk factors of progression to MC, such as early-onset MG and respiratory infection. IVIg is an effective treatment. With proper immunosuppressive therapy, this group of patients had an overall good long-term prognosis.

Pharmacological Management of Myasthenia Gravis: A Century of Expert Opinions in Cecil Textbook of Medicine

BACKGROUND

Advances in drug therapy for myasthenia gravis have had a significant impact on the quality of life and work potential of a substantial majority of affected persons and has contributed to a remarkable decrease in the frequency and severity of complications, hospitalizations, and mortality.

STUDY QUESTION

What are the milestones of the changes in the expert approach to the pharmacological management of myasthenia in the past century?

STUDY DESIGN

To determine the changes in the experts' approach to the management of myasthenia gravis, as presented in a widely used textbook in the United States.

DATA SOURCES

The chapters presenting the management of myasthenia gravis in the 26 editions of Cecil Textbook of Medicine published from 1927 to 2020.

RESULTS

Adequate feeding, absolute rest in bed, and "tonics" were the only interventions recommended for the care of patients with myasthenia gravis in 1927. Ephedrine and glycine were used in the early 1930s. Treatment with the anticholinesterases physostigmine and neostigmine was recommended in 1937, 3 years after Mary Walker discovered it in the United Kingdom. Immunosuppressant pharmacological interventions with prednisone and azathioprine have been considered the standard since 1975, and intravenous immune globulin was added to usual care in 1996. The newer immunosuppressant drugs mycophenolate, cyclosporine, and tacrolimus have expanded the arsenal since 2008, and the monoclonal antibodies rituximab and eculizumab have been mentioned in the textbooks published in 2012-2020. The first randomized clinical trial of drug therapy for myasthenia gravis was published in 1987.

CONCLUSIONS

The pharmacological management of myasthenia gravis was revolutionized by the epiphany of an astute clinician in the 1930s. Immunosuppressant treatment was a logical step once the autoimmune nature of the condition was established. The major therapeutic advances highlight the values of empiricism and persistent attention to detail in treating relatively rare chronic disorders.

Disappearance of Anti-Thyroid Autoantibodies following Thymectomy in Patients with Myasthenia Gravis

OBJECTIVES

The thymus plays a central role in immune tolerance, which prevents autoimmunity. Myasthenia gravis (MG) is commonly associated with thymoma or thymus hyperplasia, and it can coexist with autoimmune thyroid diseases. However, the role of the thymus in thyroid autoimmunity remains to be clarified, which we investigated here.

STUDY DESIGN

The study design entailed the inclusion of consecutive MG patients and the measurement of anti-thyroid autoantibodies at baseline and, limited to autoantibody-positive patients, also at 24 and 48 weeks. One hundred and seven MG patients were studied. The main outcome measure was the behaviour of anti-thyroglobulin autoantibodies (TgAbs) and anti-thyroperoxidase autoantibodies (TPOAbs) over time in relation to thymectomy.

RESULTS

Serum TgAbs and/or TPOAbs were detected in ∼20% of patients in the absence of thyroid dysfunction. The prevalence of positive serum TgAbs and/or TPOAbs decreased significantly (p = 0.002) over the follow-up period in patients who underwent thymectomy, but not in patients who were not thymectomized. When the analysis was restricted to TgAbs or TPOAbs, findings were similar. On the same line, there was a general trend towards a reduction in the serum concentrations of anti-thyroid autoantibodies in patients who underwent thymectomy, which was significant for TPOAbs (p = 0.009).

CONCLUSIONS

Our findings suggest a role of the thymus in the maintenance of humoral thyroid autoimmunity.

Diagnosis of Myasthenia Gravis

The diagnosis of autoimmune Myasthenia Gravis (MG) remains clinical and rests on the history and physical findings of fatigable, fluctuating muscle weakness in a specific distribution. Ancillary bedside tests and laboratory methods help confirm the synaptic disorder, define its type and severity, classify MG according to the causative antibodies, and assess the effect of treatment objectively. We present an update on the tests used in the diagnosis and follow-up of MG and the suggested approach for their application.

Benefit and danger from immunotherapy in myasthenia gravis

In the last years, significant advances have improved the knowledge of myasthenia gravis (MG) immunopathogenesis and have enabled to realize new molecules with a selective action targeting compounds of the immunological system. This review discusses emerging treatments for MG, including complement inhibitors, neonatal Fc receptor targeting agents, and B cell interfering drugs, focusing on benefit and danger. In the second section of the review, several related adverse events of immunotherapy, including MGonset, are debated.

Human Leukocyte Antigen Class II associations in late-onset Myasthenia Gravis

Objective

Genetic factors predisposing to late‐onset myasthenia gravis (LOMG) have not been clearly defined yet. However, genome‐wide association studies identified Human Leukocyte Antigen (HLA) Class II alleles as a hotspot in this disease subtype. The aim of this study was to analyze the correlations of HLA Class II alleles with clinical data and titin antibodies in this patient subgroup.

Methods

This study consecutively enrolled anti‐acetylcholine receptor antibody‐positive, non‐thymoma patients with generalized LOMG. All patients were of Italian ancestry. HLA‐DRB1 and ‐DQB1 genotyping and serum titin antibody testing were performed in this population.

Results

A total of 107 patients (females: 28/107, 26.2%; median age of onset: 68 years, range: 50‐92) were included. We found a positive association with HLA‐DRB1*07 (P = 1.1 × 10^‐5), HLA‐DRB1*14 (P = 0.0251) and HLA‐DQB1*02 (P = 0.0095). HLA‐DRB1*03, HLA‐DRB1*11, and HLA‐DQB1*03 were protective alleles (P = 7.9 × 10^‐5, P = 0.0104, and P = 0.0067, respectively). By conditional haplotype analysis, HLA‐DRB1*07‐DQB1*02 was found to be the major risk haplotype (OR = 4.10; 95% C.I.: 2.80‐5.99; P = 6.01 × 10^‐11). The mean age at onset was 73.4 years in DRB1*07 homozygotes, 69.7 years in heterozygotes, and 66.6 in non‐carriers (P = 0.0488). DRB1*07 carriers and non‐carriers did not differ in disease severity and response to therapy. Titin antibodies were detected in 61.4% of the cases, having no association with HLA alleles or specific clinical characteristics.

Interpretation

In our study, we identified the HLA DRB1*07‐DQB1*02 haplotype as a predisposing factor for the development of generalized LOMG in the Italian population.

Iatrogenic Kaposi's sarcoma in myasthenia gravis: learnings from two case reports

Introduction

Myasthenia gravis (MG) is an autoimmune neuromuscular disease whose treatment encompasses acetylcholinesterase inhibitors, oral steroids, and other immunosuppressants. Kaposi’s sarcoma (KS) is a lymphangioproliferative disease associated with human herpesvirus 8 (HHV-8) infection and immunodeficiency or immunosuppression, mainly corticosteroids.

Case reports

We present two cases of MG patients treated with oral steroids who developed KS. Patient 1 was diagnosed with three oral KS lesions. Prednisone was discontinued with lesion regression and stabilization, while azathioprine and pyridostigmine prompted control of MG. Patient 2 developed KS lesions on the trunk and lower limbs while taking prednisone and azathioprine. Steroid tapering was started but new oral and lymph nodal lesions appeared. Paclitaxel therapy was introduced and the patient experienced pulmonary embolism and developed sensitive neuropathy. Complete remission of KS lesions was achieved and maintained with azathioprine and pyridostigmine as MG medications.

Conclusions

KS is an uncommon but clinically relevant adverse event (AE) often induced by steroid therapy. It can be controlled by steroid withdrawal but could necessitate chemotherapy, which associates with further potential AEs. Skin evaluation should be performed in all patients with chronic steroid therapy. Steroid-sparing strategies, including new drugs, could reduce KS and other steroid-related comorbidities. HHV-8 testing should be considered before starting chronic immunosuppression.

Outcome measures and treatment effectiveness in late onset myasthenia gravis

Background

Recently different subtypes of myasthenia gravis (MG) have been described. They differ for clinical features and pathogenesis but the prognosis and response to treatment is less clear. The aim of the study was to evaluate outcome and treatment effectiveness including side effects in late onset MG (LOMG) compared with early onset MG (EOMG).

Methods

We analysed retrospectively 208 MG patients. Clinical features were recorded as well as treatment and side effects. Outcome at the last follow-up was evaluated with MGSTI and MGPIS scales.

Results

The 208 patients included were classified as follow: 36 ocular MG, 40 EOMG, 72 LOMG, 25 thymoma-associated, 14 anti-MuSK and 21 double seronegative. Similar positive outcome was achieved in either early and late onset subgroup. We found pharmacological remission and minimal manifestations at the MGFA-PIS in the 95% and 94,4% of EOMG and LOMG respectively but in LOMG a lower dose of immunosuppressors (MGSTI< 2) was required compared to EOMG (p = 0,048). Severe side effects were present in a small percentage of patients in both group but diabetes was more frequent in LOMG vs EOMG (2,2% vs 5%, p = 0.017).

Conclusions

Despite LOMG has more comorbidities that might interfere with treatment and outcome, therapeutic management does not seem to differ between EOMG and LOMG. A similar positive outcome was seen in both subgroups but LOMG group seems to require lower doses of medication to control symptoms.

Case Report: Orbital Myositis and Myasthenia Gravis as Symptoms of Immune Reconstitution Inflammatory Syndrome in a Patient With Human Immunodeficiency Virus Infection

We present a case of a 37-year-old man with HIV infection who had been on antiretroviral therapy for one year. He was admitted to our hospital with red and swollen eyes, acute onset progressive exophthalmos, and intermittent diplopia endured for 7 days. His symptoms, exam, and imaging led to a diagnosis of immune reconstitution inflammatory syndrome associated orbital myositis. His symptoms improved considerably after glucocorticoid therapy. Following a reduction in the oral prednisone dose, he re-presented with left ptosis, which rapidly progressed to bilateral ptosis. Diagnostic testing led to the diagnosis of immune mediated myasthenia gravis. Treatment with pyridostigmine bromide, prednisone, and tacrolimus was initiated. One month later, the patient's symptoms improved significantly. There was a probable association between his symptoms and autoimmune immune reconstitution inflammatory syndrome. This report highlights the importance of recognizing autoimmune disorders in human immunodeficiency virus-infected patients undergoing antiretroviral therapy. Orbital myositis and myasthenia gravis in human immunodeficiency virus-infected patients correlate closely with immunity status following a marked increase in CD4⁺ T cell counts.

Traditional Chinese medicine for myasthenia gravis: Study protocol for a network meta-analysis

BACKGROUND

Myasthenia gravis (MG) is a disease that is difficult to cure, mainly manifested in the affected skeletal muscle weakness and morbid fatigue, which seriously affects the patients' daily life and work. A large number of randomized controlled trial have shown that Traditional Chinese medicine (TCM) has a good effect in treating MG. However, due to the variety of TCM treatment methods, its relative effectiveness and safety have not been verified. Therefore, this study will use a network meta-analysis method to verify the effectiveness and safety of different types of TCM in the treatment of MG.

METHODS

We will search the following databases from inception to June 2020: the China National Knowledge Infrastructure, Wanfang Database, Chinese Science and Technology Periodical Database, Chinese Biomedical Literature Database, Pubmed, Embase, Web of Science, and the Cochrane library. Collect all randomized controlled trial of TCM for the treatment of MG, The 2 authors will independently select studies and extract data based on pre-designed inclusion and exclusion criteria. Methodological quality assessment and risk of bias will be assessed using Cochrane bias risk tool. All data analysis will be conducted using Revman5.3, WinBUGS 1.4.3, and Stata14.2 software.

RESULTS

This study will directly and indirectly compare the different outcome indicators of various studies, and rank the effectiveness of different TCM methods. The main outcome indicators include effectiveness, remission rate (no drug symptoms), relapse rate, clinical absolute score, and relative score. Secondary outcome indicators: including any related adverse reactions, the concentration of acetylcholine receptor antibody in serum.

CONCLUSION

The conclusion of this systematic review will provide credible Evidence-based for the relative advantages of different TCM treatment methods for MG.

Diagnosis and treatment of myasthenia gravis

PURPOSE OF REVIEW

This article provides an update on the most recent advances in diagnostic procedures and therapeutic approaches for myasthenia gravis, spanning from autoantibody and neuroelectrophysiological tests as diagnostic tools, to innovative and promising treatments based on biological drugs.

RECENT FINDINGS

Novel studies performed by cell-based assays (CBAs) indicate an improvement in the chance of identifying serum autoantibodies in myasthenic patients. Clinical trials on the use of biological drugs were recently concluded, providing important data on safety and efficacy of eculizumab, efgartigimod and amifampridine phosphate: the first, a complement blocker, showed long-term safety and efficacy in acetylcholine receptor (AChR)-positive myasthenic patients with refractory generalized disease; the second, the neonatal Fc receptor blocker, was well tolerated and clinically effective in both AChR-specific and muscle-specific kinase receptor (MuSK)-positive patients; the third, a blocker of presynaptic potassium channels, was found to be well tolerated and effective in MuSK-positive patients.

SUMMARY

CBAs can lead to a significant reduction of seronegative patients, improving myasthenia gravis diagnostic process. New biological drugs offer innovative approaches to treat myasthenic patients with generalized disease, promising to change the paradigm of treatment and to significantly enhance therapeutic success within a precision medicine framework.

Exacerbation of myasthenia gravis after amoxicillin therapy: a case series

INTRODUCTION

Myasthenia gravis (MG) can be aggravated by several classes of drugs, including antibiotics. Penicillins are considered safe drugs for the management of infectious disease in patients with MG. However, a few cases of MG exacerbations after penicillin treatment have been reported in literature.

CASE REPORTS

We report six patients with MG developing acute worsening of symptoms after amoxicillin or amoxicillin/clavulanate treatment. In most of the cases, symptoms started in a few days after antibiotic administration. In all cases, we observed a worsening of the Myasthenia Gravis Foundation of America (MGFA) clinical classification. Most patients required a therapeutic intervention with dosage increase of the previous therapy or the introduction of new drugs for MG. All patients had a full recovery to baseline neurological conditions within 1-2 months.

CONCLUSIONS

We concluded that patients receiving amoxicillin should be closely monitored for possible acute relapse.

Acupuncture for ocular myasthenia gravis: A protocol for systematic review and meta-analysis

BACKGROUND

The aim of this systematic review with meta-analysis is to determine the efficacy and security of acupuncture in treatment of ocular myasthenia gravis and find out whether or not the quick short-term efficacy of acupuncture exists.

METHODS

The following electronic databases will be searched by 2 independent reviewers: PubMed, Cochrane Library, EMBASE, Springer, China National Knowledge Infrastructure, Wanfang, and Chinese Biomedical Literature Database. All randomized controlled trials on acupuncture for ocular myasthenia gravis published in electronic databases from inception to March 1, 2020, with language restricted in Chinese and English will be included in the study.Methodologic quality is assessed by 2 blinded reviewers independently screen and score the articles using the PEDro scale and the Cochrane Collaboration risk of bias tool. A meta-analysis was performed when there is sufficient clinical homogeneity in at least 2 studies. The Grading of Recommendations Assessment, Development and Evaluation approach is used to rate the body of evidence in each meta-analysis. When the quantitive evaluation is not available, a qualitative description of the results of single study is provided.

RESULTS

An evidence of variety of acupuncture treatment methods for treating ocular myasthenia gravis will be illustrated using subjective reports and objective measures of performance. The primary outcomes consisted of effective rate, MGFA PIS, QMG, and MG-composite. Secondary outcomes involve clinical absolute and relative score, titers of AchR antibodies, and the side effects. The treatment frequency and courses will be measured.

CONCLUSION

This protocol will present the evidence of whether acupuncture is an effective and safe intervention for ocular myasthenia gravis.

TRIAL REGISTRATION NUMBER

CRD42019141325.

Practical approach to respiratory emergencies in neurological diseases

Many neurological diseases may cause acute respiratory failure (ARF) due to involvement of bulbar respiratory center, spinal cord, motoneurons, peripheral nerves, neuromuscular junction, or skeletal muscles. In this context, respiratory emergencies are often a challenge at home, in a neurology ward, or even in an intensive care unit, influencing morbidity and mortality. More commonly, patients develop primarily ventilatory impairment causing hypercapnia. Moreover, inadequate bulbar and expiratory muscle function may cause retained secretions, frequently complicated by pneumonia, atelectasis, and, ultimately, hypoxemic ARF. On the basis of the clinical onset, two main categories of ARF can be identified: (i) acute exacerbation of chronic respiratory failure, which is common in slowly progressive neurological diseases, such as movement disorders and most neuromuscular diseases, and (ii) sudden-onset respiratory failure which may develop in rapidly progressive neurological disorders including stroke, convulsive status epilepticus, traumatic brain injury, spinal cord injury, phrenic neuropathy, myasthenia gravis, and Guillain-Barré syndrome. A tailored assistance may include manual and mechanical cough assistance, noninvasive ventilation, endotracheal intubation, invasive mechanical ventilation, or tracheotomy. This review provides practical recommendations for prevention, recognition, management, and treatment of respiratory emergencies in neurological diseases, mostly in teenagers and adults, according to type and severity of baseline disease.

The associations of HLA-DRB1 gene polymorphisms with late-onset myasthenia gravis: a meta-analysis

BACKGROUND

Late-onset myasthenia gravis (LOMG) is one of the major subgroups of the MG. Intensive evidence suggested that polymorphisms in HLA-DRB1 gene were associated with LOMG risk, but the results remained inconsistent. Therefore, a meta-analysis is conducted to make a more precise evaluation between HLA-DRB1 alleles and LOMG.

METHODS

The PubMed, EMBASE, Cochrane library, Chinese National Knowledge Infrastructure (CNKI), and Wan Fang and Technology of Chongqing (VIP) Database were searched for eligible studies. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were applied to assess the association between HLA-DRB1 alleles and LOMG.

RESULTS

A total of 11 studies involving 5513 people were included in our meta-analysis. The results showed that DRB1 07 and 0403 alleles were risk factors for LOMG (1.83 [1.12, 2.98], P = 0.02; 7.05 [2.62, 18.92], P = 0.0001, respectively), while DRB1 0301 and 1301 alleles were identified as protective factors for LOMG (0.44 [0.31, 0.62], P < 0.00001; 0.38 [0.23, 0.62], P = 0.0001, respectively). As for the HLA-DRB1 04 and 14 alleles, our subgroup analysis showed that there were significant associations between these alleles and LOMG in Caucasians (2.21 [1.14, 4.27], P = 0.02; 2.82 [1.29, 6.14], P = 0.009, respectively).

CONCLUSIONS

These results confirmed the association of DRB1 alleles (0301, 04, 0403, 07, 1301, and 14) and LOMG, which might provide potential promising biomarkers for prediction of LOMG risk.

Autoimmune Channelopathies at Neuromuscular Junction

The neuromuscular junction, also called myoneural junction, is a site of chemical communication between a nerve fiber and a muscle cell. There are many types of channels at neuromuscular junction that play indispensable roles in neuromuscular signal transmission, such as voltage-gated calcium channels and voltage-gated potassium channels on presynaptic membrane, and acetylcholine receptors on post-synaptic membrane. Over the last two decades, our understanding of the role that autoantibodies play in neuromuscular junction disorders has been greatly improved. Antibodies against these channels cause a heterogeneous group of diseases, such as Lambert-Eaton syndrome, Isaacs' syndrome and myasthenia gravis. Lambert-Eaton syndrome is characterized by late onset of fatigue, skeletal muscle weakness, and autonomic symptoms. Patients with Isaacs' syndrome demonstrate muscle cramps and fasciculation. Myasthenia gravis is the most common autoimmune neuromuscular junction channelopathy characterized by fluctuation of muscle weakness. All these disorders have a high risk of tumor. Although these channelopathies share some common features, they differ for clinical features, antibodies profile, neurophysiological features, and treatments. The purpose of this review is to give a comprehensive insight on recent advances in autoimmune channelopathies at the neuromuscular junction.