Prevalence and impact of autoimmune thyroid disease on myasthenia gravis course

Autoimmune and Non-Autoimmune Comorbidities in Myasthenic Patients of East-European Descent: A Case-Control Study

Background: As the life expectancy of patients with myasthenia gravis (MG) is improving, so the number of comorbidities continues to rise, with a potentially significant impact on the overall morbidity and mortality. The main aim of the study was to assess comorbidities of MG in a group of patients of East-European descent. Methods: We retrospectively compared 185 adult myasthenic patients with 895 sex- and age-matched controls, admitted from January 2013 to December 2021. Results: Of these patients, 60% had late-onset MG (LOMG), with a clear predominance of women in both the LOMG and early-onset (EOMG) types; and 23.8% of the patients had a radiological description consistent with thymoma. All myasthenic patients had at least one comorbidity; 20 (10.8%) of the patients associated at least one autoimmune comorbidity. Obesity (p < 0.01), type 2 diabetes (p < 0.0001), cerebrovascular diseases (p < 0.0001), essential hypertension (p < 0.01), and cardiac arrythmias (p < 0.0001) were more frequent in patients than in the control group. The granulocyte-to-lymphocyte ratio was higher in the myasthenic patients compared to the controls (p < 0.01 for LOMG). Discussion: We, thus, suggest a common chronic low-grade inflammatory background as a possible connection between MG subtypes and some of these apparently unconnected comorbidities. Conclusions: The East-European origin of the patients offered a different social and cultural angle of a disease studied mainly on populations of West-European and Asian descent.

Bidirectional association between hypothyroidism and myasthenia gravis: a Mendelian randomized study

OBJECTIVES

Although observational studies have suggested a link between hypothyroidism and myasthenia gravis (MG), a causal relationship has not been established. We aimed to investigate the causal association using a two-sample Mendelian randomization (MR) study.

METHODS

Using summary statistics from genome-wide association studies involving 494,577 and 38,243 individuals, single-nucleotide polymorphisms exhibiting no linkage disequilibrium (r2 ≤ 0.001) and displaying significant differences (p ≤ 5 × 10-8) were selected for hypothyroidism and MG. To assess the potential causality relationship between hypothyroidism and MG, MR analysis was conducted using inverse variance weighted (IVW), weighted median method, and MR-Egger. The MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test were employed to examine sensitivity analyses. In addition, validation datasets were used to validate the relevant results.

RESULTS

Genetic liability to hypothyroidism was positively associated with MG (IVW, OR: 1.36, 95% CI: 1.17-1.58, p = 7.53 × 10-05; weighted median, OR: 1.19, 95% CI: 0.70-2.02, p = 0.522; MR-Egger, OR: 1.19, 95% CI: 0.98-1.45, p = 0.080). Among the three MR methods, the correlation between hypothyroidism and MG genetic prediction was consistent. The independent validation set (IVW, OR: 466.47, 95% CI: 4.70 -46,285.95, p = 0.01) further supported this. Additionally, bidirectional studies showed that using IVW, there was no reverse causality (OR: 1.104, 95%CI: 0.96-1.27, p = 0.170).

DISCUSSION

This MR study showed that hypothyroidism can increase the risk of MG. Further investigation into the underlying mechanisms of this potential causality is warranted to offer novel therapeutic options for MG in the future.

Clinical features of myasthenia gravis with neurological and systemic autoimmune diseases

Multiple reports on the co-existence of autoimmune diseases and myasthenia gravis (MG) have raised considerable concern. Therefore, we reviewed autoimmune diseases in MG to explore their clinical presentations and determine whether the presence of autoimmune diseases affects the disease severity and treatment strategies for MG. We reviewed all the major immune-mediated coexisting autoimmune conditions associated with MG. PubMed, Embase and Web of Science were searched for relevant studies from their inception to January 2023. There is a higher frequency of concomitant autoimmune diseases in patients with MG than in the general population with a marked risk in women. Most autoimmune comorbidities are linked to AChR-MG; however, there are few reports of MuSK-MG. Thyroid disorders, systemic lupus erythematosus, and vitiligo are the most common system autoimmune diseases associated with MG. In addition, MG can coexist with neurological autoimmune diseases, such as neuromyelitis optica (NMO), inflammatory myopathy (IM), multiple sclerosis (MS), and autoimmune encephalitis (AE), with NMO being the most common. Autoimmune diseases appear to develop more often in early-onset MG (EOMG). MS coexists more commonly with EOMG, while IM coexists with LOMG. In addition, MG complicated by autoimmune diseases tends to have mild clinical manifestations, and the coexistence of autoimmune diseases does not influence the clinical course of MG. The clinical course of neurological autoimmune diseases is typically severe. Autoimmune diseases occur most often after MG or as a combined abnormality; therefore, timely thymectomy followed by immunotherapy could be effective. In addition, thymoma-associated AChR MG is associated with an increased risk of AE and IM, whereas NMO and MS are associated with thymic hyperplasia. The co-occurrence of MG and autoimmune diseases could be attributed to similar immunological mechanisms with different targets and common genetic factor predisposition. This review provides evidence of the association between MG and several comorbid autoimmune diseases.

Neurologic Complications of Endocrine Disorders

OBJECTIVE

This article provides an overview of the neurologic complications of the most prevalent endocrine disorders in adults with an emphasis on relevant neurologic symptoms, signs, and laboratory and neuroimaging findings.

LATEST DEVELOPMENTS

Although the mechanisms of many of the neurologic complications discussed here remain unclear, our understanding of the impacts of diabetes and hypothyroidism on the nervous system and muscle, including complications of rapid correction of chronic hyperglycemia, has advanced in recent years. Recent large studies have not demonstrated a convincing association between subclinical or overt hypothyroidism and cognitive decline.

ESSENTIAL POINTS

Neurologists must become familiar with the neurologic complications of endocrine disorders not only because they are common and treatable (and often reversible) but also because they may be iatrogenic, as is the case with adrenal insufficiency in the setting of long-term corticosteroid therapy.

Comparison of Short-Term Post-Thymectomy Outcomes by Time-Weighted Dosages of Drug Requirements between Thymoma and Non-Thymoma Myasthenia Gravis Patients

(1) Background: Early thymectomy is suggested in all clinically indicated myasthenia gravis (MG) patients. However, short-term clinical response after thymectomy in MG patients has been limitedly described in the literature. This study aimed to compare the 5-year post-thymectomy outcomes between thymoma (Th) and non-thymoma (non-Th) MG patients. (2) Methods: MG patients aged ≥18 years who underwent transsternal thymectomy and had tissue histopathology reports in Songklanagarind Hospital between 2002 and 2020 were enrolled in a retrospective review. The differences in the baseline demographics and clinical characteristics between ThMG and non-Th MG patients were studied. We compared the time-weighted averages (TWAs) of daily required dosages of pyridostigmine, prednisolone or azathioprine to efficiently maintain daily living activities and earnings between the MG patient groups during 5 consecutive years following thymectomy. Post-thymectomy clinical status, exacerbations or crises were followed. Descriptive statistics were used for analysis with statistical significance set at p < 0.05. (3) Results: ThMG patients had significantly older ages of onset and shorter times from the MG diagnosis to thymectomy. Male gender was the only significant factor associated with ThMG. TWAs of the daily MG treatment drug dosages required showed no differences between the groups. Additionally, the rates of exacerbations and crises were not different, but decremental trends were shown in both groups after the thymectomies. (4) Conclusions: The daily dosage requirements of MG treatment drugs were not different. There was a trend of decreasing adverse event rates despite no statistically significant differences during the first 5 years after thymectomy in ThMG and non-ThMG patients.

Differences in immunophenotypes between myasthenia gravis patients with and without thyroid antibodies

INTRODUCTION/AIMS

Immunophenotypes are related to the therapeutic efficacy of specific immunomodulating agents in patients with myasthenia gravis (MG), but the relationship of immunophenotype to the presence or absence of thyroid antibodies is unknown. This study aims to evaluate differences in the immunophenotypes between MG patients with and without thyroid antibody (TAb) positivity to provide insight for future targeted immunotherapies.

METHODS

This retrospective observational study included 48 MG patients with acetylcholine receptor antibody (AchR-Ab), of which 15 (31.25%) were TAb positive. Ocular MG (OMG) was defined as ocular-only manifestations for the duration for which records were available. Peripheral lymphocyte subpopulations were measured by flow cytometry.

RESULTS

TAb positive patients appeared to have a higher prevalence of OMG than TAb negative patients (53.33% vs. 24.24%, P  = 0.048). Percentages of B cells (mean difference (MD) = 6.16, 95% confidence interval (CI): 1.91 to 10.40, P = 0.007) and CD8 + CD28+ cells (MD = 15.14, 95%CI: 5.17 to 25.11, P  = 0.013) were higher in TAb positive patients than those in TAb negative patients, while AChR-Ab titers (MD = -6.49 nmol/L, 95%CI: -9.29 to -3.70, P  < 0.001), percentages of T cells (MD = -6.43, 95%CI: -11.92 to -0.94, P = 0.023), CD3 + HLA-DR+ cells (MD = -6.47, 95%CI: -12.31 to -0.63, P  = 0.031) and CD8+ T cells (MD = -6.60, 95%CI: -9.86 to -3.34, P < 0.001) were lower.

DISCUSSION

The immunophenotypes of MG patients with and without TAb positivity were significantly different, suggesting that their sensitivity to immunotherapy may be different. Further studies focused on differences between TAb positive and TAb negative MG patients in their responses to specific immunotherapies are needed to support our exploratory findings. This article is protected by copyright. All rights reserved.

Comorbid Autoimmune Diseases in Patients With Myasthenia Gravis: A Retrospective Cross-Sectional Study of a Chinese Cohort

Introduction: The phenomenon of coexisting autoimmune diseases (ADs) in patients with myasthenia gravis (MG) has attracted considerable attention. However, few studies have investigated the burden and potential clinical associations of ADs in Chinese MG cohorts.

Methods: In this retrospective cross-sectional study, we reviewed the records of 1,132 patients with MG who were admitted to Huashan Hospital Fudan University from August 2013 to August 2020. Patients were excluded if they had incomplete medical records (n = 336).

Results: Comorbid ADs were found in 92 of 796 Chinese patients with MG (11.6%), among which, hyperthyroidism (6.7%), hypothyrosis (2.6%), and vitiligo (0.8%) were predominant. Patients with MG with ADs were predominantly female, younger at the onset of MG symptoms, and had a lower frequency of thymoma. Compared to the general population, we found a significantly higher percentage of hyperthyroidism (8.5-fold increase, p < 0.001), hypothyrosis (2.6-fold increase, p < 0.001), vitiligo (1.3-fold increase, p < 0.001), rheumatoid arthritis (1.4-fold increase, p < 0.001), immune thrombocytopenic purpura (193.1-fold increase, p < 0.001), autoimmune hemolytic anemia (7.4-fold increase, p < 0.001), autoimmune hepatitis (5.1-fold increase, p < 0.001), and polymyositis (11.5-fold increase, p < 0.001) in patients with MG with ADs. Patients with MG with ADs presented a lower proportion of previous history of MC (0 vs. 5.6%, p < 0.05) than those without ADs. The proportion of MGFA Class I at onset in patients with MG with ADs was significantly higher than that in patients with MG without ADs (77.0 vs. 52.7%, p < 0.05). The proportion of MuSK-positive in patients with MG with ADs was significantly lower than that in patients with MG without ADs (0 vs. 4.8%, p < 0.05).

Conclusion: In conclusion, we observed a higher frequency of concurrent ADs in a Chinese MG cohort. Furthermore, MG combined with ADs tended to have mild clinical presentation.

Calculation of Similarity Between 26 Autoimmune Diseases Based on Three Measurements Including Network, Function, and Semantics

Autoimmune diseases (ADs) are a broad range of diseases in which the immune response to self-antigens causes damage or disorder of tissues, and the genetic susceptibility is regarded as the key etiology of ADs. Accumulating evidence has suggested that there are certain commonalities among different ADs. However, the theoretical research about similarity between ADs is still limited. In this work, we first computed the genetic similarity between 26 ADs based on three measurements: network similarity (NetSim), functional similarity (FunSim), and semantic similarity (SemSim), and systematically identified three significant pairs of similar ADs: rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), myasthenia gravis (MG) and autoimmune thyroiditis (AIT), and autoimmune polyendocrinopathies (AP) and uveomeningoencephalitic syndrome (Vogt-Koyanagi-Harada syndrome, VKH). Then we investigated the gene ontology terms and pathways enriched by the three significant AD pairs through functional analysis. By the cluster analysis on the similarity matrix of 26 ADs, we embedded the three significant AD pairs in three different disease clusters respectively, and the ADs of each disease cluster might have high genetic similarity. We also detected the risk genes in common among the ADs which belonged to the same disease cluster. Overall, our findings will provide significant insight in the commonalities of different ADs in genetics, and contribute to the discovery of novel biomarkers and the development of new therapeutic methods for ADs.

Lower BAFF Levels in Myasthenic Patients Treated with Glucocorticoids

B-cell activating factor (BAFF), a member of tumor necrosis factor family, activates B cells, promotes their survival and proliferation. BAFF is considered to have an influence on development of autoimmune diseases including myasthenia gravis (MG). We aimed to evaluate BAFF serum levels in MG patients, their potential connection with therapy and course of MG. Cross-sectional study. Two hundred eighteen adult patients with MG (67% women, age: 18-89 years, 82.6% AChR antibody seropositive (AChRAb(+)). Serum BAFF levels, their relationship with severity of clinical symptoms, therapy conducted, clinical and demographic features and other factors were analyzed. Patients with AChRAb(+) MG demonstrated significantly higher BAFF levels than MuSK-MG patients (831.2 ± 285.4 pg/ml vs. 745.6 ± 633.4 pg/ml, respectively; p = 0.030). Serum BAFF levels in women were significantly higher than in men (855.9 ± 302.5 vs. 756.6 ± 289.4, respectively; p = 0.017). Mean serum BAFF level was significantly decreased in patients who were ever treated with corticosteroids (CS) (770.4 ± 327.8 pg/ml vs. 891.3 ± 246.1 pg/ml, respectively; p = 0.001). Thymoma-MG patients demonstrated significantly lower BAFF levels (671.2 ± 244.9 vs. 833.5 ± 302.4, respectively; p = 0.044). Thymectomized patients did not differ in BAFF levels from the MG patients who had not undergone thymectomy. In multiple linear regression model, recent CS therapy and male sex were found to be independent predictors of lower BAFF levels. Serum BAFF level is decreased in patients treated with CS, which may suggest inhibiting influence of CS on BAFF-a potential mechanism contributing to the effectiveness of such therapy.

Comorbidities worsen the prognosis of generalized myasthenia gravis post-thymectomy

BACKGROUND

The effect of comorbidities on the prognosis of myasthenia gravis (MG) remains unclear. In particular, the role of other autoimmune diseases (AD) is controversial.

METHODS

In this retrospective single-center cohort study, we investigated 154 consecutive generalized thymectomized MG patients, with a mean follow-up time of 8.6 (±5.0) years post-thymectomy. Comorbidities diagnosed at any timepoint were retrieved from medical records and Charlson comorbidity index (CCI) scores were calculated. Patients were categorized into subgroups MG alone (n = 45) and MG with any comorbidity (n = 109); the latter was further categorized into MG with other ADs (n = 33) and MG with non-AD comorbidities (n = 76). The endpoints analyzed were complete stable remission (CSR), minimal need for medications, and need for in-hospital treatments.

RESULTS

CSR was more frequent in MG alone than in MG with any comorbidity group (26.7% vs 8.3%, p = 0.004). Minimal need for medication was reached more often in the MG alone than in the MG with non-AD comorbidities group (p = 0.047). Need for in-hospital treatments was lower in the MG alone group than in MG patients with any comorbidity (p = 0.046). Logistic regression analysis revealed that lower CCI scores increased the likelihood of CSR (p = 0.033). Lower CCI scores were more prevalent both in patients with minimal need for medication and in patients who did not need in-hospital treatments (p < 0.001).

CONCLUSIONS

Patients with generalized MG and comorbidities have a poorer prognosis than patients with MG alone during almost 9 years follow-up after thymectomy. AD comorbidities appeared not to translate into a higher risk compared to other comorbidities.

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.

Physical fatigability and muscle pain in patients with Hashimoto thyroiditis

Introduction

Hashimoto thyroiditis (HT) may lead to muscle weakness due to hypothyroid dysfunction. However, clinical experience treating patients with HT suggests that neuromuscular symptoms may develop in these patients despite long-standing euthyroidism.

Methods

In 24 euthyroid patients with HT and 25 healthy controls, physical fatigability was assessed using the arm movement test (AMT) and 6-min walk test (6MWT). Fatigability was based on calculation of linear trend (LT) reflecting dynamic performance within subsequent constant time intervals. Perception of physical fatigue and muscle pain was analyzed using fatigue (FSMC) and pain questionnaires. Obtained results were correlated with clinical, neurophysiological and lab findings.

Results

HT patients showed a negative LT in 6MWT significantly differing from stable performance in controls. LT in AMT did not differ between HT and controls. FSMC scores and pain perception revealed significantly higher levels in HT patients than in controls. Physical FSMC score was primarily influenced by pain perception (standardized regression coefficient, beta = 0.633, p = 0.002). Neither pain score nor physical fatigue score showed a correlation with LT in 6MWT nor did mood, or anti-TPO antibody titer.

Conclusion

A significant physical fatigability could be shown in euthyroid HT patients despite missing obvious neuromuscular deficits in routine testing. Further, elevated pain and fatigue perception in HT patients seem to contribute to nonspecific muscle complaints in these patients. A possible pathogenic role of thyroid autoimmunity in hidden neuromuscular involvement may be suggested.

Autoimmune disorders and paraneoplastic syndromes in thymoma

Thymomas are counted among the rare tumour entities which are associated with autoimmune disorders (AIDs) and paraneoplastic syndromes (PNS) far more often than other malignancies. Through its complex immunological function in the context of the selection and maturation of T cells, the thymus is at the same time highly susceptible to disruptive factors caused by the development and growth of thymic tumours. These T cells, which are thought to develop to competent immune cells in the thymus, can instead adopt autoreactive behaviour due to the uncontrolled interplay of thymomas and become the trigger for AID or PNS affecting numerous organs and tissues within the human body. While myasthenia gravis is the most prevalent PNS in thymoma, numerous others have been described, be they related to neurological, cardiovascular, gastrointestinal, haematological, dermatological, endocrine or systemic disorders. This review article sheds light on the pathophysiology, epidemiology, specific clinical features and therapeutic options of the various forms as well as courses and outcomes of AID/PNS in association with thymomas. Whenever suitable and backed by the limited available evidence, the perspectives from both the thymoma and the affected organ/tissue will be highlighted. Specific issues addressed are the prognostic significance of thymectomy on myasthenia gravis and other thymoma-associated AID/PND and further the impact and safety of immunotherapies on AID and PND relating to thymomas.

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.

Immunotherapy in myasthenia gravis in the era of biologics

No consensus has been reached on the ideal therapeutic algorithm for myasthenia gravis (MG). Most patients with MG require induction therapy with high doses of corticosteroids and maintenance with an immunosuppressant. Severe cases and acute worsening require intravenous immunoglobulin or plasmapheresis before oral immunosuppressants start having an effect. However, biologics are emerging as important therapeutic tools that promise to provide better corticosteroid sparing effects than standard treatments and can even induce remission. In particular, eculizumab, a monoclonal antibody against complement C5, has been approved by the FDA for refractory MG on the basis of a phase III trial. Rituximab, an anti-CD20 monoclonal antibody that depletes peripheral B cells, has also been effective in many large uncontrolled series, although was not in a small phase III trial. Whether the newer anti-CD20 agents ocrelizumab, ofatumumab, obinutuzumab, ublituximab or inebilizumab will be more effective remains unclear. Belimumab, an antibody against the B cell trophic factor BAFF, was ineffective in phase III trials, and efgartigimod, which depletes antibodies, was effective in a phase II study. Some anti-cytokine agents relevant to MG immunopathogenesis also seem promising. Checkpoint inhibitors can trigger MG in some patients, necessitating early intervention. Increased availability of new biologics provides targeted immunotherapies and the opportunities to develop more specific therapies.

Impact of autoimmune comorbidity on fatigue, sleepiness and mood in myasthenia gravis

BACKGROUND

Disease burden in myasthenia gravis (MG) and in other autoimmune disorders is often determined by common accompanying symptoms such as fatigue, sleepiness and mood disturbances. Many MG patients have a second autoimmune disease, but it is unclear whether autoimmune comorbidities add to the severity of fatigue, sleepiness and mood disturbances.

METHODS

We ascertained the presence of autoimmune comorbidities in 69 well-characterized MG patients. To assess fatigue, sleepiness and mood disturbances, we applied the Fatigue Severity Scale (FSS), the Fatigue Impact Scale (FIS), the Epworth Sleepiness Scale (ESS), as well as the Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI) to all patients.

RESULTS

Thirteen MG patients had concomitant autoimmune thyroid disease (AITD), including 1 patient with rheumatoid arthritis as third autoimmune disease. Fatigue (68.1%), excessive daytime sleepiness (14.5%), moderate-severe depression (20.3%) and anxiety (26.1%) were common, but MG patients with and without autoimmune comorbidities had similar FSS, FIS, ESS, BDI and STAI scores. The presence of autoimmune comorbidities was not associated with altered clinical and immunological MG characteristics, but MG patients with autoimmune comorbidities have more often been treated with corticosteroids than patients without autoimmune comorbidities (92.3% vs. 60.7%; p = 0.03).

CONCLUSIONS

While many MG patients were affected by fatigue, sleepiness, depression and anxiety, the present study does not suggest that coexisting autoimmune diseases substantially contribute to the magnitude of these cumbersome comorbid symptoms. However, the higher frequency of steroid treatment may have counterbalanced the effects of the autoimmune comorbidity.

Ocular myasthenia gravis: an update on diagnosis and treatment

PURPOSE OF REVIEW

Myasthenia gravis is an autoimmune disease that commonly affects the palpebral and extraocular muscles. Ocular myasthenia gravis (OMG) is a variant of the disease that is confined to the ocular muscles but frequently becomes generalized over time. The diagnosis of OMG is often challenging but both clinical and laboratory findings are helpful in confirming the clinical suspicion. This review provides an update on the diagnostic approach and therapeutic options for OMG.

RECENT FINDINGS

Antimuscle-specific tyrosine kinase and LDL-related receptor-related protein 4 are newly available serologic testing for myasthenia gravis that can help in increasing the diagnostic sensitivity of OMG. They should be included to the diagnostic algorithm of OMG in appropriate clinical situations.

SUMMARY

OMG remains a primarily clinical diagnosis, but recent advances in laboratory testing can improve the diagnostic accuracy and should be used in appropriate clinical settings. The mainstay of treatment for OMG has not significantly changed over the past years, but the increasing availability of steroid-sparing agents improved the disease control while minimizing steroid-induced complications.

Gender and quality of life in myasthenia gravis patients from the myasthenia gravis foundation of America registry

INTRODUCTION

Quality of life (QOL) has been poorly characterized among patients with myasthenia gravis (MG) other than assessments performed within the clinical setting.

METHODS

Patients age ≥ 18 years who were diagnosed with MG and registered with the MG patient registry between July 1, 2013, and June 30, 2016, were included. Demographic information, disease related history, and QOL were compared between men and women using multivariable analysis.

RESULTS

A total of 1,315 subjects (827 women) were included. Women were significantly younger, had a younger age at symptom onset, and were more likely to have thymoma and thymectomy. The 15-item Myasthenia Gravis Quality of Life scale (MG-QOL15) was significantly worse in women. MG-QOL15 score was comparable between women who had thymectomy and men with or without thymectomy.

DISCUSSION

QOL among MG patients is worse in women compared with men, but this disparity is eliminated in women who have undergone thymectomy. Muscle Nerve, 2018.

Myasthenic Crisis Complicated with Myxedema, Positive for Both Anti-acetylcholine Receptor and Anti-muscle-specific Tyrosine Kinase Antibodies

We herein report the case of myasthenic crisis occurring in a 51-year-old man. He had experienced ptosis, increased body weight with edema, and fatigue with dyspnea. He presented at our emergency department with disturbed consciousness. He was originally diagnosed with myxedema coma, and he required artificial respiration. Because his weakness persisted and he was positive for anti-acetylcholine receptor antibodies and anti-muscle-specific tyrosine kinase antibodies, we diagnosed myasthenic crisis after various examinations. His clinical response to treatment was good and he was discharged in an ambulatory status 3 months after admission. This case demonstrates that myasthenic crisis may occur in association with myxedema.

A Case Report of Recurrent Takotsubo Cardiomyopathy in a Patient during Myasthenia Crisis

Introduction

Patients with myasthenia crisis can develop Takotsubo stress cardiomyopathy (SC) due to emotional or physical stress and high level of circulating catecholamines. We report a patient who developed recurrent Takotsubo cardiomyopathy during myasthenia crisis. Coexisting autoimmune disorders known to precipitate stress cardiomyopathy like Grave's disease need to be evaluated.

Case Report

A 69-year-old female with seropositive myasthenia gravis (MG), Grave's disease, and coronary artery disease on monthly infusion of intravenous immunoglobulin (IVIG), prednisone, pyridostigmine, and methimazole presented with shortness of breath and chest pain. Electrocardiogram (ECG) showed ST elevation in anterolateral leads with troponemia. Coronary angiogram was unremarkable for occlusive coronary disease with left ventriculogram showing reduced wall motion with apical and mid left ventricle (LV) hypokinesis suggestive of Takotsubo stress cardiomyopathy. Her symptoms were attributed to MG crisis. Her symptoms, ECG, and echocardiographic findings resolved after five cycles of plasma exchange (PLEX). She had another similar episode one year later during myasthenia crisis with subsequent resolution in 10 days after PLEX.

Conclusion

Takotsubo cardiomyopathy can be one of the manifestations of myasthenia crisis with or without coexisting Grave's disease. These patients might benefit from meticulous fluid status and cardiac monitoring while administering rescue treatments like IVIG and PLEX.

Hickam's dictum: Myasthenia Gravis presenting concurrently with Graves' disease

We present two patients with Graves' disease and concurrent myasthenia gravis. The impact of the dual diagnosis on the clinical course and the potential for a delayed diagnosis of myasthenia gravis is discussed. Patient 1, a 28-year-old man was diagnosed with Graves' disease following his second respiratory arrest. His history was strongly suggestive of a second pathology. Patient 2, a 66-year-old Cantonese woman with established Graves' disease presented with thionamide-related neutropaenia. Examination revealed bilateral ptosis and right lateral rectus palsy. Both patients had thyrotoxicosis secondary to Graves' disease with concurrent myasthenia gravis. Although neuromuscular weakness is common in Graves' disease, coexisting myasthenia gravis (MG) is rare and can cause profound morbidity. Ocular signs in both diseases may cause diagnostic confusion although ptosis suggests coexisting MG. In both cases, the thyrotoxicosis delayed the diagnosis of MG.

What's in the Literature?

In this edition of this column, we review new studies concerning the pathophysiology, treatment, and outcomes of patients with necrotizing myopathy, genetic testing in congenital myopathies, and limb girdle muscular dystrophies, and the incidence of polyneuropathy in the myotonic dystrophies. Various studies in myasthenia gravis, including those concerning antibody testing, clinical features, and quality of life are also reviewed as are recent findings in congenital myasthenic syndromes. Finally, 2 studies concerning polyneuropathy are discussed, including one on the association of polyneuropathy in patients with the metabolic syndrome and one on laboratory testing in patients with otherwise idiopathic small fiber polyneuropathy.

Autoimmune Thyroiditis and Myasthenia Gravis

Autoimmune diseases (AIDs) are the result of specific immune responses directed against structures of the self. In normal conditions, the molecules recognized as "self" are tolerated by immune system, but when the self-tolerance is lost, the immune system could react against molecules from the body, causing the loss of self-tolerance, and subsequently the onset of AID that differs for organ target and etiology. Autoimmune thyroid disease (ATD) is caused by the development of autoimmunity against thyroid antigens and comprises Hashimoto's thyroiditis and Graves disease. They are frequently associated with other organ or non-organ specific AIDs, such as myasthenia gravis (MG). In fact, ATD seems to be the most associated pathology to MG. The etiology of both diseases is multifactorial and it is due to genetic and environmental factors, and each of them has specific characteristics. The two pathologies show many commonalities, such as the organ-specificity with a clear pathogenic effect of antibodies, the pathological mechanisms, such as deregulation of the immune system and the implication of the genetic predisposition. They also show some differences, such as the mode of action of the antibodies and therapies. In this review that focuses on ATD and MG, the common features and the differences between the two diseases are discussed.

Prevalence and impact of autoimmune thyroid disease on myasthenia gravis course

OBJECTIVES

Autoimmune thyroid diseases (ATDs) frequently accompany myasthenia gravis (MG) and may influence its course. We aimed to determine the association and impact of ATD with early- (<50 years), late-onset MG, or thymoma-MG.

MATERIALS AND METHODS

Prevalence of ATD was measured in a cross-sectional study of 343 consecutive patients with MG (236 F, 107 M) aged 4-89 years; 83.8% were seropositive, in 2.9%, anti-MuSK antibodies were detected. Concentrations of antithyroid peroxidase antibodies, antithyroglobulin antibodies, antithyrotropin receptor antibodies, and TSH level were measured in all patients. MG clinical course, treatment received, and treatment results were evaluated.

RESULTS

Autoimmune thyroid diseases were diagnosed in 92 (26.8%) of MG patients including 4.4% with Graves (GD), 9% with Hashimoto thyroiditis (HT), and 13.4% with antithyroid antibodies only. GD patients had ocular symptoms more often than patients with antithyroid antibodies or HT (p = .008). ATD prevalence was comparable in MG with early and late onset, while non-ATDs were more frequent in thymoma-MG (p = .049). Immunosuppressive therapy was less frequently needed in the patients with MG and ATD, indirectly indicating milder MG course (p = .005). Risk of myasthenic crisis and the results of treatment did not differ between patients with and without ATD.

CONCLUSIONS

Autoimmune thyroid diseases are frequently accompanied by early-and late-onset MG, while thymoma-MG is related to higher risk of non-ATD. Myasthenia coexisting with ATD follows milder course than MG alone.