Myasthenia Gravis and Associated Diseases

Defective autophagy and autophagy activators in myasthenia gravis: a rare entity and unusual scenario

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ) that results from autoantibodies against nicotinic acetylcholine receptors (nAchRs) at NMJs. These autoantibodies are mainly originated from autoreactive B cells that bind and destroy nAchRs at NMJs preventing nerve impulses from activating the end-plates of skeletal muscle. Indeed, immune dysregulation plays a crucial role in the pathogenesis of MG. Autoreactive B cells are increased in MG due to the defect in the central and peripheral tolerance mechanisms. As well, autoreactive T cells are augmented in MG due to the diversion of regulatory T (Treg) cells or a defect in thymic anergy leading to T cell-mediated autoimmunity. Furthermore, macroautophagy/autophagy, which is a conserved cellular catabolic process, plays a critical role in autoimmune diseases by regulating antigen presentation, survival of immune cells and cytokine-mediated inflammation. Abnormal autophagic flux is associated with different autoimmune disorders. Autophagy regulates the connection between innate and adaptive immune responses by controlling the production of cytokines and survival of Tregs. As autophagy is involved in autoimmune disorders, it may play a major role in the pathogenesis of MG. Therefore, this mini-review demonstrates the potential role of autophagy and autophagy activators in MG.Abbreviations: Ach, acetylcholine; Breg, regulatory B; IgG, immunoglobulin G; MG, myasthenia gravis; NMJ, neuromuscular junction; ROS, reactive oxygen species; Treg, regulatory T; Ubl, ubiquitin-like.

Systemic Inflammatory Response Index, a Potential Inflammatory Biomarker in Disease Severity of Myasthenia Gravis: A Pilot Retrospective Study

Purpose

Myasthenia gravis (MG) is a chronic autoimmune disease caused by neuromuscular junction (NMJ) dysfunction. Our current understanding of MG's inflammatory component remains poor. The systemic inflammatory response index (SIRI) presents a promising yet unexplored biomarker for assessing MG severity. This study aimed to investigate the potential relationship between SIRI and MG disease severity.

Patients and Methods

We conducted a retrospective analysis of clinical data from 171 MG patients admitted between January 2016 and June 2021. Patients with incomplete data, other autoimmune diseases, or comorbidities were excluded. Disease severity was evaluated using the Myasthenia Gravis Foundation of America (MGFA) classification and Myasthenia Gravis Activities of Daily Living (MG-ADL) on admission. The association between SIRI and disease severity was assessed through logistic regression analysis, along with receiver operating characteristic (ROC) curve and decision curve analysis (DCA) comparisons with established inflammation indicators.

Results

After exclusion, 143 patients were analyzed in our study. SIRI levels significantly differed between patients with higher and lower disease severity (p < 0.001). Univariate logistic regression showed that SIRI had a significant effect on high disease severity (OR = 1.376, 95% CI 1.138-1.664, p = 0.001). This association remained significant even after adjusting for age, sex, disease duration, history of MG medication and thymoma (OR = 1.308, 95% CI 1.072-1.597, p = 0.008). Additionally, a positive correlation between SIRI and MG-ADL was observed (r = 0.232, p = 0.008). Significant interactions were observed between SIRI and immunosuppressor (p interaction = 0.001) and intravenous immunoglobulin (p interaction = 0.005). DCA demonstrated the superior net clinical benefit of SIRI compared to other markers when the threshold probability was around 0.2.

Conclusion

Our findings indicate a strong independent association between SIRI and disease severity in MG, suggesting SIRI's potential as a valuable biomarker for MG with superior clinical benefit to currently utilized markers.

Myasthenia Gravis Treatment: From Old Drugs to Innovative Therapies with a Glimpse into the Future

Myasthenia gravis (MG) is a rare autoimmune disease that causes debilitating muscle weakness due to impaired neuromuscular transmission. Since most (about 80-90%) MG patients present autoantibodies against the acetylcholine receptor, standard medical therapy consists of symptomatic treatment with acetylcholinesterase inhibitors (e.g., pyridostigmine). In addition, considering the autoimmune basis of MG, standard therapy includes immunomodulating agents, such as corticosteroids, azathioprine, cyclosporine A, and cyclophosphamide. New strategies have been proposed for the treatment of MG and include complement blockade (i.e., eculizumab, ravulizumab, and zilucoplan) and neonatal Fc receptor antagonism (i.e., efgartigimod and rozanolixizumab). The aim of this review is to provide a detailed overview of the pre- and post-marketing evidence on the five pharmacological treatments most recently approved for the treatment of MG, by identifying both preclinical and clinical studies registered in clinicaltrials.gov. A description of the molecules currently under evaluation for the treatment of MG is also provided.

Genetic, serological and clinical evaluation of childhood myasthenia syndromes- single center subgroup analysis experience in Turkey

BACKGROUND

Congenital myasthenic syndrome is a disease that occurs due to several types such as mutations in different pre-synaptic, synaptic, post-synaptic proteins and, glycosylation defects associated with congenital myopathy. Juvenile myasthenia gravis is an autoimmune condition usually caused by antibodies targeting the acetylcholine receptor.

AIMS

Our objective is to conduct an analysis on the subgroup traits exhibited by patients who have been diagnosed with congenital myasthenic syndrome and juvenile myasthenia gravis, with a focus on their long-term monitoring and management.

METHODS

This study was conducted on children diagnosed with myasthenia gravis, who were under the care of Dokuz Eylul University's Department of Pediatric Neurology for a period of ten years.

RESULTS

A total of 22 (12 congenital myasthenic syndrome, 10 juvenile myasthenia gravis) patients were identified. Defects in the acetylcholine receptor (6/12) were the most common type in the congenital myasthenic syndrome group. Basal-lamina-related defects (5/12) were the second most prevalent. One patient had a GFPT1 gene mutation (1/12). Patients with ocular myasthenia gravis (n = 6) exhibited milder symptoms. In the generalized myasthenia gravis group (n = 4), specifically in postpubertal girls, a more severe clinical progression was observed, leading to the implementation of more aggressive treatment strategies.

CONCLUSION

This study highlights that clinical recognition of congenital myasthenic syndrome and knowledge of related genes will aid the rapid diagnosis and treatment of these rare neuromuscular disorders. Findings in the juvenile myasthenia gravis group demonstrate the impact of pubertal development and the need for timely and appropriate active therapy, including thymectomy, to improve prognosis.

Myasthenia gravis as initial presentation of a pancreatic neuroendocrine tumor: A case report

Myasthenia gravis (MG) is a heterogeneous autoimmune disease, which is characterized by a postsynaptic neuromuscular transmission defect, with antibodies directly targeting the acetylcholine receptor (AChR) or other structural proteins of the neuromuscular junction. The majority of MG cases are associated with thymic pathologies, including thymoma, thyroiditis, autoimmune diseases or malignant hematologic neoplasia. The present study reported a rare case of AChR-positive and late-onset ocular MG, which rapidly progressed to a generalized myasthenic syndrome as an initial presentation of a pancreatic neuroendocrine neoplasia (pNEN). Following complete surgical resection of the pNEN, the myasthenic syndrome was improved and the anti-AChR antibody titers were reduced. It has been reported that MG is a paraneoplastic syndrome in thymic neoplasms and less common in hematologic malignancies. However, currently, only few cases of MG as initial presentation of a solid tumor, and more particular of a neuroendocrine neoplasm, have been reported in the literature. In conclusion, surveillance for extrathymic solid malignancies in newly diagnosed patients with MG could promote the early diagnosis of associated tumor diseases.

Diagnosis and Management of Seronegative Myasthenia Gravis: Lights and Shadows

Myasthenia gravis (MG) is an antibody-mediated neuromuscular disease affecting the neuromuscular junction. In most cases, autoantibodies can be detected in the sera of MG patients, thus aiding in diagnosis and allowing for early screening. However, there is a small proportion of patients who have no detectable auto-antibodies, a condition termed "seronegative MG" (SnMG). Several factors contribute to this, including laboratory test inaccuracies, decreased antibody production, immunosuppressive therapy, immunodeficiencies, antigen depletion, and immune-senescence. The diagnosis of SnMG is more challenging and is based on clinical features and neurophysiological tests. The early identification of these patients is needed in order to ensure early treatment and prevent complications. This narrative review aims to examine the latest updates on SnMG, defining the clinical characteristics of affected patients, diagnostic methods, management, and therapeutic scenarios.

Simultaneous Myasthenic Crisis With Thyrotoxic Crisis in an Adult Male: An Autoimmune Overlap

When it comes to thyroid disorders, Graves' disease (GD) is the most prevalent autoimmune thyroid disorder in which antibodies are formed against thyroid receptors. Myasthenia gravis (MG) is a rare autoimmune neuromuscular junction disorder. Autoimmune antibodies are formed against postsynaptic neuromuscular junctions in MG, interrupting neuromuscular transmission and causing variable muscle weakness and tiredness. It affects older men and young women. The two disorders may coexist in a patient, or either of them may develop first. The thyroid condition GD is most frequently linked to MG. This case report describes an older man who presented with an acute exacerbation of MG along with a thyrotoxic crisis.

A Comprehensive Literature Review on Managing Systemic Lupus Erythematosus: Addressing Cardiovascular Disease Risk in Females and Its Autoimmune Disease Associations

This review aimed to evaluate the mechanism of premature cardiovascular disease (CVD) in systemic lupus erythematosus (SLE) patients, particularly in the female population, and emphasize the need for early management interventions; explore the association between SLE and two autoimmune diseases, myasthenia gravis (MG) and antiphospholipid antibody syndrome (APS), and their management strategies; and evaluate the effectiveness of pharmacological and non-pharmacological interventions in managing SLE, focusing on premenopausal females, females of childbearing age, and pregnant patients. We conducted a comprehensive literature review to achieve these objectives using various databases, including PubMed, Google Scholar, and Cochrane. The collected data were analyzed and synthesized to provide an evidence-based overview of SLE, its management strategies as an independent disease, and some disease associations. The treatment should be focused on remission, preventing organ damage, and improving the overall quality of life (QOL). Extensive emphasis should also be focused on diagnosing SLE and concurrent underlying secondary diseases timely and managing them appropriately.

Evaluation of the quality of patient involvement in a patient-led analysis of the lived experience of a rare disease

BACKGROUND

Patients themselves are best placed to provide insights on the lived experience and to lead the analysis of such insights to bring the patient voice into peer-reviewed literature. In doing so, they can meet the authorship criteria for subsequent research publications. It is important to evaluate patient engagement to identify ways to improve future collaborations. Here, we describe the approach taken during a patient-led and patient co-authored analysis of the lived experience of generalized myasthenia gravis, which may be applicable to other indications. We also assessed the quality of patient engagement throughout the research project.

METHODS

We used self-reported experience surveys based on the Patient Focused Medicines Development Patient Engagement Quality Guidance criteria for assessing patient engagement. The surveys were adapted to focus on individual projects and assessed eight domains using a five-point Likert scale. In September 2020, we invited eight patient council members to complete a self-reported experience survey following qualitative lived experience data generation. We calculated the average experience score as a percentage of the maximum possible score. Patient authors (n = 1) and non-patient authors (n = 3) were invited to complete a similar survey in November 2021, with questions customized for relevance, to evaluate the authorship experience following publication of the research.

RESULTS

Overall, patient council members had a positive experience of taking part in this study, with an average experience score of 90% (71.6/80.0; n = 8). The patient author and non-patient authors rated their authorship experience highly, with average experience scores of 92% (78.0/85.0) and 97% (63.3/65.0), respectively. There were key aspects that contributed to the overall project success (e.g., ensuring that all participants were aligned on the project objectives at the outset and understood their roles and responsibilities). We also identified elements of the approach that could be improved in future collaborations.

CONCLUSION

In this patient-led analysis, patient council members, patient authors and non-patient authors had a positive experience of being involved in the project. We gained useful insights into elements that contributed to the project's success and ways to improve future patient-led projects on the lived experience.

Patient-reported impact of myasthenia gravis in the real world: findings from a digital observational survey-based study (MyRealWorld MG)

OBJECTIVES

This study aims to explore the impact of myasthenia gravis (MG) - in terms of treatments, side effects, comorbidities, psychological health and work or study- in the real world from a patient perspective.

DESIGN AND PARTICIPANTS

This is a prospective, observational, digital, longitudinal study. Adults diagnosed with MG residing in the USA, Japan, Germany, the UK, Italy, Spain or Canada were eligible to participate in the study. There were no other exclusion criteria. Participants used a bespoke smartphone application to confirm eligibility, provide consent and enter data about their MG into a profile, a tracker to record MG-related events and a series of patient-reported outcome instruments. 1693 participants completed at least 1 survey and were included in this analysis.

RESULTS

Results are presented as a percentage of respondents to each survey question. The study population was largely female (69% of 1586 respondents), with an average age of 49.9 years (SD 14.8). In the previous 12 months, 83.7% of 1412 respondents confirmed that they had received one or more routine treatments for MG, and 67.1% of 255 respondents confirmed that they had experienced a side effect in the previous month. Commonly experienced comorbidities reported by 966 respondents were thyroid problems, hypertension and anxiety, experienced by 37.5%, 31.4% and 28.0% of respondents, respectively.According to 889 respondents to the Hospital Anxiety and Depression Scale survey, 52.7% and 43.2% had a score indicative of at least mild anxiety and mild depression, respectively. Of 257 respondents, 33.0% reported experiencing a work or study impact in the past month.

CONCLUSIONS

This analysis of baseline characteristics of the MyRealWorld MG study population indicates that, despite current treatments, patients experience notable burden. Further scheduled analyses will develop a longitudinal picture of MG burden.

TRIAL REGISTRATION NUMBER

NCT04176211.

Anti-dsDNA Is Associated with Favorable Prognosis in Myasthenia Gravis: A Retrospective Study

Objectives. To investigate the presence of serum antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-dsDNA) in patients with myasthenia gravis (MG) and analyze the clinical characteristics and prognostic factors associated with MG. Methods. We retrospectively enrolled 363 patients with MG and analyzed the clinical characteristics and follow-up data between patients positive and negative for ANA and anti-dsDNA. We defined a Myasthenia Gravis Activities of Daily Living (MG-ADL) reduction as a main prognosis predictor and used logistic regression to determine independent factors associated with prognosis. We built a nomogram to predict prognosis and evaluate the internal validity of the model. Results. Ninety-eight (27.0%) patients were positive for ANA, and 51 (14.0%) were positive for anti-dsDNA. Patients positive for ANA and anti-dsDNA antibodies tended to be female and positive for acetylcholine receptor antibody (AChR-Ab). The rate of thymoma was higher in anti-dsDNA-positive patients with MG (p-dsDNA-MG) than in patients negative for anti-dsDNA (49.0% vs. 26.0%, $p=0.001$ ), and p-dsDNA-MG was associated with reduced MG-ADL score. Regression analysis showed that except for age of onset ( $\text{OR}=0.986$ , $95\%\text{CI}=0.973–0.999$ , $p=0.037$ ), anti-dsDNA ( $\text{OR}=2.800$ , $95\%\text{CI}=1.381–5.679$ , $p=0.004$ ), ptosis ( $\text{OR}=2.930$ , $95\%\text{CI}=1.827–4.699$ , $p<0.001$ ), and eye movement disorder ( $\text{OR}=2.815$ , $95\%\text{CI}=1.672–4.741$ , $p<0.001$ ) were independent predictive factors of a favorable prognosis of MG. These predictors were used to generate a nomogram with an excellent predictive value. Conclusions. Being female and the presence of AChR-Ab were features of ANA- or anti-dsDNA-positive MG. The presence of anti-dsDNA was associated with a favorable prognosis of MG.

The Lived Experience of Myasthenia Gravis: A Patient-Led Analysis

Introduction

A greater understanding of the reality of living with myasthenia gravis (MG) may improve management and outcomes for patients. However, there is little published data on the patient perspective of how MG impacts life. Our objective was to reveal the lived experience of MG from the patient perspective.

Methods

This analysis was led by an international Patient Council comprising nine individuals living with MG who serve as local/national patient advocates in seven countries (Europe and the United States). Insights into the lived experience of MG were consolidated from three sources (a qualitative research study of 54 people with MG or their carers from seven countries; a previous Patient Council meeting [September 2019]; and a literature review). Insights were prioritised by the Patient Council, discussed during a virtual workshop (August 2020) and articulated in a series of statements organised into domains. Overarching themes that describe the lived experience of MG were identified by the patient authors.

Results

From 114 patient insights and supporting quotes, the Patient Council defined 44 summary statements organised into nine domains. Five overarching themes were identified that describe the lived experience of MG. These themes include living with fluctuating and unpredictable symptoms; a constant state of adaptation, continual assessment and trade-offs in all aspects of life; treatment inertia, often resulting in under-treatment; a sense of disconnect with healthcare professionals; and feelings of anxiety, frustration, guilt, anger, loneliness and depression.

Conclusion

This patient-driven analysis enriches our understanding of the reality of living with MG from the patient perspective.

Myasthenia Gravis-An Analysis of Multimodal Evoked Potentials

INTRODUCTION

The aim of this study is a comprehensive analysis of the parameters of exogenous evoked potentials (visual, brainstem auditory, and somatosensory) in patients with myasthenia gravis (MG), a prototype of both neuromuscular junction disease and autoimmune disease. The study also seeks to isolate electrophysiological changes that may indicate disorders within the central and/or peripheral nervous system.

METHODS

A total of forty-two consecutive patients with myasthenia gravis (24 women, 18 men) were included in the study. All of the patients underwent EP examination. MR images were also analyzed.

RESULTS

In the group of MG patients, the latency of P100 (113.9 ± 13.9; p < 0.0001) VEP, wave III (3.92 ± 0.29; p = 0.015), wave V (5.93 ± 0.32; <0.0001), interlatency III-V (2.00 ± 0.12; p < 0.0001), interlatency I-V (4.20 ± 0.28; p < 0.001) BAEP, and all components of SEP (N9, P10, N13, P16, N20, P22) were significantly longer. Mean wave I and V amplitude BAEP were relatively lower.

CONCLUSIONS

The results of the study suggest the presence of disturbances in the bioelectric activities of the central and peripheral nervous system in MG patients.

The role of thymectomy in myasthenia gravis: A programmatic approach to thymectomy and perioperative management of myasthenia gravis

BACKGROUND

Myasthenia gravis is a rare autoimmune disease caused by antibodies that probably originate from the thymus glands. This study examined the epidemiology of patients with MG, who underwent thymectomy over the last three decades.

METHODS

The objectives of this observational study were to investigate the clinicopathological features, treatment modalities, and prognostic factors for patients with thymic masses, over three decades at the Royal Hospital, Muscat, Oman.

RESULTS

There were 100 patients who underwent thymectomy with a mean (SD) age of 32.0 (8.6) years, of which 20% were men and 80% were women. Their follow up period, cardiac and neurology clinics, ranged from 1.5 to 12.0 years with a mean (SD) of 6.0 (3.0) years. Small percentage of MG patients had diabetes and hypertension and 10% of patients have positive family history of MG. Symptoms at the onset of the disease were ophthalmoplegia in 75%, limb weakness in 39%, bulbar symptoms in 57% and respiratory symptoms in 39% of patients. The Osserman grading was Grade I - 5%, Grade IIA - 39%, Grade IIB - 34%, and Grade III - 22%. Post thymectomy, 21% of patients had complete clinical remission, 76% of patients had significant clinical improvement and 3% had no apparent improvement in their clinical status. Histologically, hyperplasia was found in 57% and involuted thymus in 18% of patients.

CONCLUSION

Thymectomy can reduce patient's need for medication and reduce the severity of MG regardless of age, sex, severity, or length of sickness, or thymic masses. The early-onset, sever M.G, female, thymic hyperplasia benefit the most. Patients classified as Osserman Class IIA and IIB benefit most from this procedure.

Pediatric Autoimmune Ocular Myasthenia Gravis: Evaluation of Presentation and Treatment Outcomes in a Large Cohort

BACKGROUND

In autoimmune myasthenia gravis (MG), autoantibodies target the neuromuscular junction. Ocular myasthenia gravis (OMG) is localized, affecting only extraocular and/or levator palpebrae muscles. OMG presents across all ages, varying in presentation, treatment modalities, and outcomes. Recently, there have been advances in MG/OMG treatment; their utilization and effectiveness are an important part of optimal disease management.

METHODS

We completed a retrospective chart review of children aged 18 years or younger with a confirmed diagnosis of OMG presenting from 2002 to 2019.

RESULTS

Forty-two patients were included with mean age at presentation of 8.5 years (2 to 18 years). Twenty-one patients (50%) had positive antibodies; 90% had acetylcholine receptor antibodies. Ten patients developed generalized symptoms with mean time to generalization of 13.6 months. Multiple logistic regression showed that older age of onset was a trend predictive factor (P = 0.054; odds ratio 1.17) for generalized disease. All patients were treated with pyridostigmine. Immunomodulating agents included steroids (15), mycophenolate mofetil (four), and intravenous immunoglobulin (one). Three patients underwent thymectomy. Twenty patients reached minimal manifestation status, and 12 achieved remission. Gender, race, and positive antibody status were not statistically significant predictors for advanced immunosuppressive therapy.

CONCLUSIONS

We summarize one of the largest cohorts of pediatric patients with OMG who have undergone up-to-date diagnostic and therapeutic regimens. The predictors of outcome and treatment pathway for OMG patients suggested by this report may be further elucidated by future prospective studies.

Association Between Myasthenia Gravis and Systemic Lupus Erythematosus as a Comorbid State

Systemic lupus erythematosus (SLE) and myasthenia gravis (MG) are autoimmune states which have presentational similitude. Both conditions test serologically positive for anti-nuclear antibodies and require exceptional differential diagnostic acumen to segregate one from the other. The hypothesized factors provoking these diseases may be immunological, genetic, hormonal, or environmental and can be better understood by large-scale controlled epidemiological studies. Biochemical factors such as variation in CXC (an α chemokine subfamily), CXCL13, and granulocyte-macrophage colony-stimulating factor levels are assumed to play a pivotal role in the pathogenesis of SLE and MG; however, further studies are required to understand their exact mechanism and effect on the underlying autoimmune diseases. Following this, another precipitating factor for this overlap is believed to be thymectomy which is performed to eliminate MG symptoms. Although thymectomy is the effective treatment modality in MG patients, other findings and data support the view that this procedure may lead to the development of other autoimmune states such as SLE. It is evident from previously published data and case reports that patients with one autoimmune disease who underwent thymectomy contracted SLE and became more susceptible to other autoimmune diseases compared to the general population. Post-thymectomy follow-up of patients provides us with mechanistic clues for understanding the development of SLE-MG overlap; hence, in MG patients who have undergone thymectomy, any clinical and immune serological SLE suspicion should be carefully evaluated.

Cancer in myasthenia gravis subtypes in relation to immunosuppressive treatment and acetylcholine receptor antibodies: A Swedish nationwide register study

BACKGROUND AND PURPOSE

The potentially increased risk of extrathymic cancers in myasthenia gravis (MG) remains uncertain. We present the occurrence of extrathymic cancer diagnoses in different MG subgroups.

METHODS

We conducted a nationwide Swedish register-based cohort study, including patients who had their first MG diagnosis or first prescription of acetylcholine esterase inhibitors between the years 2006 and 2018. Timing and subtypes of cancer diagnosis in relation to MG as well as corticosteroid-sparing immunosuppressants (CSISs) were identified from national patient, cancer and drug registers.

RESULTS

In the study population of 2812 MG patients, 92 had juvenile MG (3%), 632 had early-onset MG (23%), 1968 had late-onset MG (LOMG; 70%) and 120 patients had thymoma-associated MG (TAMG; 4%). Extrathymic cancers were observed in 630 patients (22.4%). Skin cancer and cancer in the male genital organs were most common (N = 138, respectively), followed by cancers in the female genital organs (N = 103), digestive organs (N = 90) and breast (N = 80). Patients with TAMG (29.2%) and LOMG (28.4%) had the highest occurrence of extrathymic cancer. Cancer frequency was comparable between acetylcholine receptor antibody seropositive and seronegative patients. Two or more CSIS prescriptions significantly increased the frequency of cancer, especially cancers in the digestive organs (p = 0.0026), male genital organs (p = 0.0037) and skin (p < 0.0001).

CONCLUSIONS

Most extrathymic cancer types in MG were observed in TAMG and LOMG patients, and there was a clear correlation between CSIS exposure and cancer risk. This study sheds light on extrathymic cancers also in non-thymoma MG.

Regional Features of MuSK Antibody-Positive Myasthenia Gravis in Northeast China

Objective: To summarize the characteristics of muscle-specific receptor tyrosine kinase antibody-positive myasthenia gravis (MuSK-MG) in Northeast China.

Methods: We retrospectively collected 183 confirmed MG patients and divided them into three groups based on the type of serum antibodies: MuSK-MG (14 cases), acetylcholine receptor (AChR)-MG (130 cases), and double-seronegative (DSN)-MG (39 cases). The clinical, diagnostic, therapeutic, and prognosis data were analyzed.

Results: MuSK antibody was detected in 26.7% of seronegative MG. The mean age of onset in MuSK-MG was 53.2 ± 13.6 years. Fifty percent of MuSK-MG patients with an onset symptom of pure ocular muscle weakness. The time from onset to other muscle groups' involvement and the time from onset to myasthenic crisis had no significant difference among the three groups (P > 0.05). The proportion of Osserman classification I in MuSK-MG group was lower than that in DSN-MG group. The proportion of Osserman classification IV in MuSK-MG group was higher than that in the other two groups. The incidences of other coexisting autoimmune diseases in MuSK-MG group were higher. Prognosis after the treatment of steroid combined with tacrolimus for MuSK-MG was similar to AChR-MG treated with steroid combined with an immunosuppressant agent (P > 0.05).

Conclusion: Patients with MuSK-MG in Northeast China have a modestly later onset age and a proportion of patients may have a mild form of the disease with delayed disease progression. We confirmed the existence of a rare ocular MuSK-MG phenotype, a high proportion of coexisting with other autoimmune diseases, and a good response to steroids combined with tacrolimus for our MuSK-MG series.

Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human

Caffeine occurs naturally in various foods, such as coffee, tea, and cocoa, and it has been used safely as a mild stimulant for a long time. However, excessive caffeine consumption (1~1.5 g/day) can cause caffeine poisoning (caffeinism), which includes symptoms such as anxiety, agitation, insomnia, and gastrointestinal disorders. Recently, there has been increasing interest in the effect of caffeine consumption as a protective factor or risk factor for neurological and psychiatric disorders. Currently, the importance of personalized medicine is being emphasized, and research on sex/gender differences needs to be conducted. Our review focuses on the effect of caffeine consumption on several neurological and psychiatric disorders with respect to sex differences to provide a better understanding of caffeine use as a risk or protective factor for those disorders. The findings may help establish new strategies for developing sex-specific caffeine therapies.

Myasthenia Gravis and its Association With Thyroid Diseases

Myasthenia gravis (MG) is a rare autoimmune neuromuscular junction disorder, and thyroid disorder is a disorder involving the thyroid receptor, of which Graves' disease (GD) is the most common autoimmune thyroid disorder, in which antibodies develop against thyroid receptors. Both may have similar clinical features. In myasthenia gravis, autoimmune antibodies develop against postsynaptic neuromuscular junction disrupting the neuromuscular transmission, resulting in fluctuating muscle weakness and fatigue. It is a disease of young women and older men. The two pathologies may coexist in a patient or can precede one another. Graves' disease (GD) among thyroid diseases is most often associated with MG. 

Similarities in clinical features lead to difficulty in distinguishing MG and GD. Despite the standard treatment of myasthenia gravis, including steroids, acetylcholinesterases, rituximab, immunosuppressants, and thymectomy, there is still an increased number of relapses and myasthenia crisis. Eculizumab and plasmapheresis are the two new treatment options for MG, with supporting evidence of marked improvement in recent studies. Myasthenia gravis and Graves' disease have a see-saw relationship. Treating one pathology may worsen the other, so physicians should always consider MG as a differential in patients of hyperthyroidism presenting with new symptoms of fatigue or respiratory failure or neuromuscular weakness.

In this comprehensive review article, we tried to establish an association between myasthenia gravis and Graves' disease (GD) by exploring currently available literature from PubMed. However, more studies need to be done to establish an association between pathologies.

Prevalence and risk of thyroid diseases in myasthenia gravis

OBJECTIVES

To estimate the prevalence of thyroid diseases and the cumulative risk of thyroid diseases during a follow-up period after myasthenia gravis (MG) diagnosis compared with non-MG controls.

MATERIALS AND METHODS

We used the Taiwan National Health Insurance Database linked to Registry of Catastrophic Illness database to identify patients with MG. The controls were composed of those who did not have MG and were matched with the MG patients by sex, age, and the index date. We recorded thyroid disease histories before and after the index date.

RESULTS

Our study included 5813 MG patients and 29 065 controls. The prevalence of thyroid diseases in the MG patients at diagnosis was 18.4%, which was nearly 3.9-fold greater than that in the control group. (Odds ratio [OR] 3.895, 95% Confidence interval [CI] 3.574-4.246) After excluding pre-existing thyroid diseases, the incidence of comorbid thyroid diseases was 8.7% in the MG patients and 4% in the control group. The MG patients had a 2.36-fold increased risk of developing thyroid diseases compared to the control group. (crude hazard ratio [HR] 2.360, 95% CI 2.095-2.659) The cumulative probabilities of developing thyroid diseases at 1, 5, and 10 years after the index date were 21.6%, 24.9%, and 28.7%, respectively, in the MG patients, while the cumulative probabilities were 6.5%, 8.8%, and 11.8%, respectively, in control group (log-rank test <0.0001).

CONCLUSIONS

The current population-based study showed a higher prevalence of pre-existing thyroid diseases and a higher cumulative probability of thyroid diseases during follow-up after MG diagnosis than in the general population.

Association Between Systemic Lupus Erythematosus and Myasthenia Gravis: Coincidence or Sequelae?

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease and myasthenia gravis (MG) is an organ-specific autoimmune disease, both may exhibit positive anti-nuclear antibodies and a female preponderance. They may have similar features and can coexist in a patient or precede one another.

This review article is based on electronic searches using PubMed as the primary database. Most of the articles used for this review were published in the last ten years with the exception of seven articles which were from 1995-2009. No guidelines have been followed. A total of 55 research articles were found related to the topic of this review article, and further scanning was done to eliminate some articles that did not meet the criteria.

The coexistence of autoimmune diseases has been reported in many cases. The prevalence of a second autoimmune disease is higher among patients with a primary diagnosis of autoimmune disease than the general population. The prevalence of SLE in MG patients or vice-versa is greater than the general population. The association has been hypothesized to many mechanisms: thymectomy resulting in loss of central tolerance and generation of autoantibodies, regulatory T cell dysfunction, the dysregulated function of Fas receptor (CD95), anti-malarial drugs directly affecting the neuromuscular junction, the role of chemokine CXCL13 and GM-CSF in the pathogenesis. The association is rare, and the presence of one should be closely followed for further progression into other diseases. More research work needs to be done for a clear conclusion.

Understanding the burden of refractory myasthenia gravis

Myasthenia gravis (MG) is an autoantibody-mediated disease that compromises the acetylcholine receptors or associated structures of the postsynaptic membrane of the neuromuscular junction. This leads to impaired neuromuscular transmission and subsequent fluctuating fatigability and weakness of ocular, bulbar, and limb skeletal muscles. Over the past few decades, there have been significant advances in our understanding of the disease pathophysiology and improvements in prognosis due to intensive care medicine and immunomodulation. Despite this, an estimated 10-20% of patients with MG do not achieve an adequate response, are intolerant to conventional treatment, or require chronic treatment with intravenous immunoglobulins or plasma separation procedures. Such patients are regarded as having MG that is 'refractory' to treatment and may represent a distinct clinical subgroup. Because the majority of patients with MG have well-controlled disease, the burden of illness in the minority with refractory disease is poorly understood and may be underestimated. However, clinically these patients are liable to experience extreme fatigue, considerable disability owing to uncontrolled symptoms, and frequent myasthenic crises and hospitalizations. Both acute adverse effects and an increased risk of comorbidity from treatment regimens may contribute to reduced quality of life. As yet, little is known concerning the impact of refractory MG on mental health and health-related quality of life. This review aims to highlight the burden of disease and unmet needs in patients with refractory MG.

Examining the Impact of Refractory Myasthenia Gravis on Healthcare Resource Utilization in the United States: Analysis of a Myasthenia Gravis Foundation of America Patient Registry Sample

Background and Purpose

Patients with refractory myasthenia gravis (MG) experience ongoing disease burden that might be reflected in their healthcare utilization. Here we examine the impact of refractory MG on healthcare utilization.

Methods

The 825 included participants were aged 18–64 years, enrolled in the Myasthenia Gravis Foundation of America Patient Registry between July 2013 and February 2018, and had been diagnosed with MG ≥2 years previously.

Results

Participants comprised 76 (9.2%) with refractory MG and 749 (90.8%) with nonrefractory MG. During the 6 months before enrollment, participants with refractory MG were significantly more likely than those with nonrefractory MG to have experienced at least one exacerbation [67.1% vs. 52.0%, respectively, p=0.01; odds ratio (OR)=1.882, 95% confidence interval (CI)=1.141–3.104], visited an emergency room at least once [43.4% vs. 27.1%, p<0.01; OR=2.065, 95% CI=1.276–3.343], been hospitalized overnight at least once (32.9% vs. 20.5%, p=0.01; OR=1.900, 95% CI=1.140–3.165), ever been admitted to an intensive care unit (ICU) (61.8% vs. 33.4%, p<0.01; OR=3.233, 95% CI=1.985–5.266), or ever required a feeding tube (21.1% vs. 9.1%, p<0.01; OR=2.671, 95% CI=1.457–4.896). A total of 75.8% younger females with refractory disease (<51 years, n=33) experienced at least one exacerbation, 69.7% had been admitted to an ICU, and 30.3% had required a feeding tube. For older females with refractory disease (≥51 years, n=33), 60.6%, 54.6%, and 6.1% experienced these outcomes, respectively (between-group differences were not significant).

Conclusions

Refractory MG is associated with higher disease burden and healthcare utilization than nonrefractory MG.

Coexistence of Systemic Lupus Erythematosus and Myasthenia Gravis: An Unusual Case of Polyautoimmunity

The relevance of polyautoimmunity, defined as the presence of 2or more autoimmune diseases in the same individual, is one of the issues not yet elucidated in medical practice. The coexistence of myasthenia gravis (MG) and systemic lupus erythematosus (SLE) is a clinical challenge due to the possible differential diagnoses of muscle involvement in patients with SLE. We present the case of a patient who came to the emergency room of Hospital Universitario San Ignacio in Bogotá, Colombia, with a previous diagnosis of SLE, who developed acute weakness in the context of a systemic infection, with a clinical and electrophysiological diagnosis of MG.