Myasthenia gravis

Advances in the study of ferroptosis and its relationship to autoimmune diseases

Ferroptosis represents a novel mode of programmed cell death characterized by the intracellular accumulation of iron and lipid peroxidation, culminating in oxidative stress and subsequent cell demise. Mounting evidence demonstrates that ferroptosis contributes significantly to the onset and progression of diverse pathological conditions and diseases, including infections, neurodegenerative disorders, tissue ischemia-reperfusion injury, and immune dysregulation. Recent investigations have underscored the pivotal role of ferroptosis in the pathogenesis of rheumatoid arthritis, ulcerative colitis, systemic lupus erythematosus, and asthma. This review provides a comprehensive overview of the current understanding of the regulatory mechanisms governing ferroptosis, particularly its interplay with iron, lipid, and amino acid metabolism. Furthermore, we explore the implications of ferroptosis in autoimmune diseases and deliberate on its potential as a promising therapeutic target for diverse autoimmune disorders.

Correlation Between the Prevalence of Myasthenia Gravis and the Frequency of Class II Human Leucocyte Antigen Alleles in Various Geographical Locations Around the World

Myasthenia gravis (MG) is an autoimmune condition characterised by muscle weakness due to antibodies produced against post-synaptic receptors. The impact of MG can be significant, especially with an ageing population. Human leukocyte antigens (HLA) are polymorphic genes associated with autoimmune conditions. Establishing the HLA alleles associated with MG may aid in the diagnosis, screening and early management of individuals at risk of MG. This research aims to establish the class II HLA alleles associated with the prevalence of MG in various regions of the world and identify the alleles that could predispose to the condition. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart and various databases including, Scopus and PubMed as well as other sources were used to find appropriate papers on HLA class II alleles associated with MG and the prevalence of MG in various countries. The frequency of selected HLA alleles in selected regions were obtained from the website, allelefrequencies.net. From this, a correlation coefficient and p-value were calculated to investigate whether the frequency of MG and the prevalence of HLA alleles had a significant association.  The results highlighted two HLA alleles, DRB1*04:04 and DRB1*03, to have a significant positive association with the prevalence of MG. The frequency of the alleles showed regional variation, with European countries, particularly Northern Europe, exhibiting the highest frequencies. A significant positive correlation between HLA-DRB1*04:04 and DRB1*03 showed with the prevalence of MG, highlighting these alleles as a possible cause of the disease. Screening for these alleles, particularly in Northern Europe, may help identify individuals susceptible to MG.

The impact of diagnosis delay on European patients with generalised myasthenia gravis

OBJECTIVE

The objective was to determine the mean duration of diagnosis delay for patients with myasthenia gravis from five European countries and explore the impact of >1 year diagnosis delay.

METHODS

Patients with myasthenia gravis (N = 387) from Europe (France/Germany/Italy/Spain/United Kingdom) and their physicians participated in the Adelphi Real World Myasthenia Gravis Disease Specific Programme™. Diagnosis delay (time from symptom onset to diagnosis) was calculated and characteristics described for patients experiencing >1 year and ≤1 year diagnosis delay. Denominators varied according to outcome as missing data were not imputed.

RESULTS

Mean (standard deviation) diagnosis delay was 363.1 (520.9) days, and 27.1% (105 out of 387) of patients experienced diagnosis delay >1 year. Among patients with >1 year and ≤1 year diagnosis delay, respectively, 69.2% (72 out of 104) and 17.4% [45 out of 259] had initially received a different diagnosis (physician-reported); 40.0% (42 out of 105) and 24.1% (68 out of 282) were Myasthenia Gravis Foundation of America class III at the time of the survey (physician-reported); 72.4% (76 out of 105) and 61.3% (173 out of 282) had fatigue (subjective physician reporting from a pre-selected list of symptoms); 30.5% (32 out of 105) and 17.4% (49 out of 282) had anxiety and 21.9% (23 out of 105) and 13.1% (37 out of 282) had depression (both subjective physician reporting from a pre-selected list, Likert-style); and mean (standard deviation) MG-QoL-15r score was 14.4 (5.50) and 12.6 (7.84) (self-reported by N = 43 and N = 74 patients, respectively).

INTERPRETATION

More than a quarter of patients with myasthenia gravis experienced diagnosis delay of >1 year. These patients had a different clinical profile with regards to severity, symptoms, comorbidities and MG-QoL-15r score, compared with patients experiencing ≤1 year diagnosis delay.

Clinical Characteristics and Outcomes of Generalized Myasthenia Gravis in Malaysia: A Single-Center Experience

BACKGROUND AND PURPOSE

Myasthenia gravis (MG) is clinically heterogeneous and can be classified into subgroups according to the clinical presentation, antibody status, age at onset, and thymic abnormalities. This study aimed to determine the clinical characteristics and outcomes of generalized MG (GMG) patients based on these subgroups.

METHODS

Medical records of MG patients from 1976 to 2023 were reviewed retrospectively. Patients with pure ocular MG were excluded. Data on demographic, clinical characteristics, laboratory features, and outcomes were analyzed.

RESULTS

This study included 120 GMG patients. There was a slight preponderance of female patients over male patients (male:female ratio=1:1.3), with the age at onset exhibiting a bimodal distribution. Female patients peaked at a lower age (21-30 years) whereas male patients peaked at a higher age (61-70 years). Most (92%, 105 of 114) patients had positive anti-acetylcholine receptor antibodies. Five patients were also tested for anti-muscle-specific tyrosine kinase antibodies, with two showing positivity. Thymectomy was performed in 62 (52%) patients, of which 30 had thymoma, 16 had thymic hyperplasia, 7 had an involuted thymus, and 6 had a normal thymus. There were significantly more female patients (68% vs. 45%, p=0.011) with early-onset disease (<50 years old) and thymic hyperplasia (33% vs. 0%, p<0.025). Most (71%) of the patients had a good outcome based on the Myasthenia Gravis Foundation of America postintervention status. GMG patients with early-onset disease had a significantly better outcome than patients with a late onset in univariate (58% vs. 37%, p=0.041) and multivariate (odds ratio=4.68, 95% confidence interval=1.17-18.64, p=0.029) analyses.

CONCLUSIONS

Female patients with early-onset MG and thymic hyperplasia had significantly better outcomes, but only early-onset disease was independently associated with a good outcome. These findings are comparable with those of other studies.

Unusual cause of muscle weakness, type II respiratory failure and pulmonary hypertension: a case report of ryanodine receptor type 1(RYR1)-related myopathy

BACKGROUND

Patients with congenital myopathies may experience respiratory involvement, resulting in restrictive ventilatory dysfunction and respiratory failure. Pulmonary hypertension (PH) associated with this condition has never been reported in congenital ryanodine receptor type 1(RYR1)-related myopathy.

CASE PRESENTATION

A 47-year-old woman was admitted with progressively exacerbated chest tightness and difficulty in neck flexion. She was born prematurely at week 28. Her bilateral lower extremities were edematous and muscle strength was grade IV-. Arterial blood gas analysis revealed hypoventilation syndrome and type II respiratory failure, while lung function test showed restrictive ventilation dysfunction, which were both worse in the supine position. PH was confirmed by right heart catheterization (RHC), without evidence of left heart disease, congenital heart disease, or pulmonary artery obstruction. Polysomnography indicated nocturnal hypoventilation. The ultrasound revealed reduced mobility of bilateral diaphragm. The level of creatine kinase was mildly elevated. Magnetic resonance imaging showed myositis of bilateral thigh muscle. Muscle biopsy of the left biceps brachii suggested muscle malnutrition and congenital muscle disease. Gene testing revealed a missense mutation in the RYR1 gene (exon33 c.C4816T). Finally, she was diagnosed with RYR1-related myopathy and received long-term non-invasive ventilation (NIV) treatment. Her symptoms and cardiopulmonary function have been greatly improved after 10 months.

CONCLUSIONS

We report a case of RYR1-related myopathy exhibiting hypoventilation syndrome, type II respiratory failure and PH associated with restrictive ventilator dysfunction. Pulmonologists should keep congenital myopathies in mind in the differential diagnosis of type II respiratory failure, especially in patients with short stature and muscle weakness.

Long-term safety and efficacy of zilucoplan in patients with generalized myasthenia gravis: interim analysis of the RAISE-XT open-label extension study

Background

Generalized myasthenia gravis (gMG) is a chronic, unpredictable disease associated with high treatment and disease burdens, with a need for more effective and well-tolerated treatments.

Objectives

To evaluate the long-term safety, tolerability, and efficacy of zilucoplan in a mild-to-severe, acetylcholine receptor autoantibody-positive (AChR+) gMG population.

Design

Ongoing, multicenter, phase III open-label extension (OLE) study.

Methods

Eligible patients had completed a qualifying randomized, placebo-controlled phase II or phase III zilucoplan study and received daily, self-administered subcutaneous 0.3 mg/kg zilucoplan. The primary endpoint was incidence of treatment-emergent adverse events (TEAEs). Secondary efficacy endpoints included change from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) score.

Results

In total, 200 patients enrolled. At the cut-off date (8 September 2022), median (range) exposure to zilucoplan in RAISE-XT was 1.2 (0.11-4.45) years. Mean age at OLE baseline was 53.3 years. A total of 188 (94%) patients experienced a TEAE, with the most common being MG worsening (n = 52, 26%) and COVID-19 (n = 49, 25%). In patients who received zilucoplan 0.3 mg/kg in the parent study, further improvements in MG-ADL score continued through to Week 24 (least squares mean change [95% confidence interval] from double-blind baseline -6.06 [-7.09, -5.03]) and were sustained through to Week 60 (-6.04 [-7.21, -4.87]). In patients who switched from placebo in the parent study, rapid improvements in MG-ADL score were observed at the first week after switching to zilucoplan; further improvements were observed at Week 24, 12 weeks after switching (-6.46 [-8.19, -4.72]), and were sustained through to Week 60 (-6.51 [-8.37, -4.65]). Consistent results were observed in other efficacy endpoints.

Conclusion

Zilucoplan demonstrated a favorable long-term safety profile, good tolerability, and sustained efficacy through to Week 60 with consistent benefits in a broad AChR+ gMG population. Additional long-term data will be available in future analyses.

Trial registration

ClinicalTrials.gov identifier: NCT04225871 (https://clinicaltrials.gov/ct2/show/NCT04225871).

Healthcare resource utilization, costs and treatment associated with myasthenia gravis exacerbations among patients with myasthenia gravis in the USA: a retrospective analysis of claims data

Aim: There are limited data on the clinical and economic burden of exacerbations in patients with myasthenia gravis (MG). We assessed patient clinical characteristics, treatments and healthcare resource utilization (HCRU) associated with MG exacerbation. Patients & methods: This was a retrospective analysis of adult patients with MG identified by commercial, Medicare or Medicaid insurance claims from the IBM® MarketScan® database. Eligible patients had two or more MG diagnosis codes, without evidence of exacerbation or crisis in the baseline period (12 months prior to index [first eligible MG diagnosis]). Clinical characteristics were evaluated at baseline and 12 weeks before each exacerbation. Number of exacerbations, MG treatments and HCRU costs associated with exacerbation were described during a 2-year follow-up period. Results: Among 9352 prevalent MG patients, 34.4% (n = 3218) experienced ≥1 exacerbation after index: commercial, 53.0% (n = 1706); Medicare, 39.4% (n = 1269); and Medicaid, 7.6% (n = 243). During follow-up, the mean (standard deviation) number of exacerbations per commercial and Medicare patient was 3.7 (7.0) and 2.7 (4.1), respectively. At least two exacerbations were experienced by approximately half of commercial and Medicare patients with ≥1 exacerbation. Mean total MG-related healthcare costs per exacerbation ranged from $26,078 to $51,120, and from $19,903 to $49,967 for commercial and Medicare patients, respectively. AChEI use decreased in patients with multiple exacerbations, while intravenous immunoglobulin use increased with multiple exacerbations. Conclusion: Despite utilization of current treatments for MG, MG exacerbations are associated with a high clinical and economic burden in both commercial and Medicare patients. Additional treatment options and improved disease management may help to reduce exacerbations and disease burden.

Disease-Based Prognostication: Myasthenia Gravis

Myasthenia gravis (MG) is an acquired autoimmune neuromuscular junction transmission disorder that clinically presents as fluctuating or persistent weakness in various skeletal muscle groups. Neuroprognostication in MG begins with some basic observations on the natural history of the disease and known treatment outcomes. Our objective is to provide a framework that can assist a clinician who encounters the MG patient for the first time and attempts to prognosticate probable outcomes in individual patients. In this review article, we explore clinical type, age of onset, antibody status, severity of disease, thymus pathology, autoimmune, and other comorbidities as prognostic factors in MG.

A decentralized, prospective, observational study to collect real-world data from patients with myasthenia gravis using smartphones

Introduction

We conducted a 3-month, prospective study in a population of patients with Myasthenia Gravis (MG), utilizing a fully decentralized approach for recruitment and monitoring (ClinicalTrials.gov Identifier: NCT04590716). The study objectives were to assess the feasibility of collecting real-world data through a smartphone-based research platform, in order to characterize symptom involvement during MG exacerbations.

Methods

Primary data collection included daily electronically recorded patient-reported outcomes (ePROs) on the presence of MG symptoms, the level of symptom severity (using the MG-Activities of Daily Living assessment, MG-ADL), and exacerbation status. Participants were also given the option to contribute data on their physical activity levels from their own wearable devices.

Results

The study enrolled and onboarded 113 participants across 37 US states, and 73% (N= 82) completed the study. The mean age of participants was 53.6 years, 60% were female. Participants were representative of a moderate to severe MG phenotype, with frequent exacerbations, high symptom burden and multiple comorbidities. 55% of participants (N=45) reported MG exacerbations during the study, with an average of 6.3 exacerbation days per participant. Median average MG-ADL scores for participants during self-reported exacerbation and non-exacerbation periods were 7 (interquartile range 4-9, range 1-19) and 0.3 (interquartile range 0-0.8, range 0-9), respectively. Analyses examining relationships between patient-reported and patient-generated health data streams and exacerbation status demonstrated concordance between self-reported MG-ADL scores and exacerbation status, and identified features that may be used to understand and predict the onset of MG symptom exacerbations, including: 1.) dynamic changes in day-to-day symptom reporting and severity 2.) daily step counts as a measure of physical activity and 3.) clinical characteristics of the patient, including the amount of time since their initial diagnosis and their active medications related to MG treatment. Finally, application of unsupervised machine learning methods identified unique clusters of exacerbation subtypes, each with their own specific representation of symptoms and symptom severity.

Conclusion

While these symptom signatures require further study and validation, our results suggest that digital phenotyping, characterized by increased multidimensionality and frequency of the data collection, holds promise for furthering our understanding of clinically significant exacerbations and reimagining the approach to treating MG as a heterogeneous condition.

Physician- and patient-reported perspectives on myasthenia gravis in Europe: a real-world survey

BACKGROUND

Myasthenia gravis (MG) is a rare, chronic, debilitating, unpredictable, and potentially life-threatening neuromuscular disease. There is a lack of real-world data on disease management that could be used to further understand and address unmet patient needs and burden. We aimed to provide comprehensive real-world insights in the management of MG in five European countries.

METHODS

Data were collected using the Adelphi Real World Disease Specific Programme™ in MG, a point-in-time survey of physicians and their patients with MG in France, Germany, Italy, Spain, and the United Kingdom (UK). Physician- and patient-reported clinical data were collected, including demographics, comorbidities, symptoms, disease history, treatments, healthcare resource utilization (HCRU), and quality of life outcomes.

RESULTS

In total, 144 physicians completed 778 patient record forms from March to July 2020 in the UK, and from June to September 2020 in France, Germany, Italy and Spain. Mean patient age at symptom onset was 47.7 years, with a mean time from symptom onset to diagnosis of 332.4 days (10.97 months). At diagnosis, 65.3% of patients were classified as Myasthenia Gravis Foundation of America Class II or above. Mean number of symptoms reported at diagnosis per patient was five, with ocular myasthenia reported in at least 50% of patients. At time of survey completion, the mean number of symptoms reported per patient was five and ocular myasthenia and ptosis were each still present in more than 50% of patients. Acetylcholinesterase inhibitors were the most commonly prescribed chronic treatments in all countries. Of 657 patients treated with chronic treatment at the time of the survey, 62% continued to experience moderate-to-severe symptoms. On average, 3.1 healthcare professionals (HCPs) were involved in patient management, 6.2 consultations were made per patient with any HCP over the last 12 months, and 178 (22.9%) patients were hospitalized in the last 12 months. Overall, HCRU and disease management were similar across all countries.

CONCLUSIONS

Our findings demonstrated the high burden of MG despite current treatment options for patients with MG.

Complement Inhibition in Myasthenia Gravis and Neuromyelitis Optica Spectrum Disorder

The complement system is a tightly controlled signaling network that plays a role in innate immune surveillance. However, abnormal signaling through this pathway contributes to tissue damage in several inflammatory, autoimmune, and degenerative diseases. Myasthenia gravis (MG) and neuromyelitis optica spectrum disorders (NMOSD) have complement dysfunction at the core of pathogenesis, providing a strong rationale for therapeutic targeting of complement components. The purpose of this paper is to briefly review the role of complement activation in the pathogenesis of MG and NMOSD, to discuss the rationale and evidence for complement inhibition as a method to manage these diseases, and to provide a Canadian perspective on the use of complement inhibition therapy through real-world cases of MG and NMOSD.

A real-world analysis of factors associated with high healthcare resource utilization and costs in patients with myasthenia gravis receiving second-line treatment

Despite current treatments, patients with myasthenia gravis (MG) experience unpredictable and inadequately controlled symptoms, lending to variability in the clinical and economic burden of disease. However, limited data are available on MG healthcare costs, and specifically, no data on patients initiating second-line therapy. Using claims data from the IBM® MarketScan® database, we assessed patient characteristics, healthcare resource utilization, and costs among MG patients initiating second-line therapy, and identified potential factors associated with high healthcare costs over a two-year follow-up period. We identified 1498 patients, of whom 49% and 31% received chronic steroids and non-steroidal immunosuppressants (NSISTs) as their second-line therapy, respectively. During follow-up, 49% experienced ≥1 MG exacerbation. Among all patients, mean all-cause total healthcare cost was $106,821 per patient during follow-up, with $88,040 and $18,780 attributed to medical and pharmacy costs, respectively. In a multivariable analysis, variables significantly associated with high cost included use of high-dose steroids, chronic intravenous immunoglobulin (IVIg, ≥6 cycles), and 1 and ≥ 4 (but not 2-3) MG exacerbations in the first year after second-line therapy initiation. Any number of exacerbations were associated with high cost in a univariable analysis. A stratified cost analysis showed that patients with >1 exacerbation, ≥1 treatment switch, and high-dose steroid use in this first year experienced $198,487, $114,037, and $79,752 mean MG-related total healthcare spend during follow-up, respectively. These data suggest that patients receiving chronic IVIg or NSISTs for MG experience significant economic burden. Disease characteristics including exacerbation and treatment history may be an indicator of future high costs.

Healthcare resource use in myasthenia gravis: a US health claims analysis

Background

There are limited data on the impact of myasthenia gravis (MG) on real-world healthcare resource use (HCRU) and patient burden in the United States.

Objectives

This study aims to assess HCRU in patients with MG using data from a US health claims database.

Design

A retrospective, database study of adult patients newly diagnosed with MG, using the IBM^® MarketScan^® Commercial Claims and Encounters and Medicare supplemental health insurance claims database.

Methods

Patients with ⩾2 MG International Classification of Disease diagnosis codes ⩾3 months apart were followed from the date of their first MG diagnosis record or start of treatment. HCRU and use of immunoglobulins and plasma exchange during follow-up was assessed, as well as comorbidities, hospitalizations, emergency room (ER) visits, intensive care unit (ICU) admissions, and specialist visits per year after diagnosis, and compared with age- and sex-matched non-MG controls.

Results

During 2010-2019, 7194 patients were followed for up to 10 years (median = 2.3 years). During follow-up, patients with MG were 2.6-fold more likely than controls to be hospitalized, and 4.5-fold more likely to be admitted to an ICU. Risk and numbers of ER admission, hospitalization, and ICU visits were the highest in the 12 months post-diagnosis of MG and were consistently higher than controls during follow-up. MG was the main cause for most hospitalizations.

Conclusion

Patients with MG have higher HCRU, compared with the age- and sex-matched non-MG controls. The early years after MG diagnosis are a period of particularly high healthcare burden, with many patients requiring hospitalization and ICU care to manage serious exacerbations.

Physician-Reported Perspectives on Myasthenia Gravis in the United States: A Real-World Survey

INTRODUCTION

Myasthenia gravis (MG) is a rare, debilitating, chronic disorder caused by the production of pathogenic immunoglobulin G autoantibodies against the neuromuscular junction. A lack of real-world studies in rare diseases reflects a relatively limited understanding of the significant unmet needs and burden of disease for patients. We aimed to provide comprehensive real-world insights into the management and burden of MG from treating physicians in the United States (US).

METHODS

Data were collected using the Adelphi Real World MG Disease Specific Programme™, a point-in-time survey of physicians and their patients with MG, in the US between March and July 2020. Physician-reported clinical data, including demographics, comorbidities, symptoms, disease history, treatments, and healthcare resource utilization, were collected.

RESULTS

In total, 456 patient record forms were completed by 78 physicians based in the US. At time of survey completion, patient mean age was 54.5 years. Mean time from symptom onset to diagnosis was 9.0 months (n = 357). Ocular symptoms were reported in 71.7% of patients. General fatigue affected 47.1% of patients and over half of those reported the severity as moderate or severe (59.5%, n = 128). Acetylcholinesterase inhibitors and/or steroids were the most frequently prescribed first-line treatment type among patients receiving treatment at time of survey completion and with moderate-to-severe symptoms (77.9%, n = 159/204). High-dose steroids (n = 14) and intravenous immunoglobulin (n = 13) were the most prescribed acute treatments among those receiving an acute treatment at time of survey completion (n = 36), with symptom exacerbations or myasthenic crises being the most common reasons for acute treatment. On average, 2.5 healthcare professionals were involved in patient management and 5.0 consultations were made per patient over the last 12 months.

CONCLUSIONS

Our findings indicated that, despite treatment, there is a proportion of patients with MG in the US who had a significant need for improved disease management.

Pharmacotherapy of Generalized Myasthenia Gravis with Special Emphasis on Newer Biologicals

Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immunoglobulin recycling and cause rapid reduction in antibody levels. Efgartigimod is an FcRn inhibitor recently approved for MG treatment, and rozanolixizumab, nipocalimab and batoclimab are other agents in clinical trial development. Although lacking high quality evidence from randomized clinical trials, clinical experience with the use of anti-CD20 rituximab has led to its use in refractory MG. Among novel targets, interleukin 6 (IL6) inhibitors such as satralizumab are promising and currently undergoing evaluation. Cutting-edge therapies include genetically modifying T cells to recognise chimeric antigen receptors (CAR) and chimeric autoantibody receptors (CAAR). These may offer sustained and long-term remissions, but are still in very early stages of evaluation. Hematopoietic stem cell transplantation (HSCT) allows immune resetting and offers sustained remission, but the induction regimens often involve serious systemic toxicity. While MG treatment is moving beyond conventional agents towards target-specific biologicals, lack of knowledge as to the initiation, maintenance, switching, tapering and long-term safety profile necessitates further research. These concerns and the high financial burden of novel agents may hamper widespread clinical use in the near future.

The Use of the Saccadometer to Identify Saccadic Characteristics in Myasthenia Gravis: A Pilot Study

BACKGROUND

Myasthenia gravis (MG) often presents with ocular signs that mimic other forms of ocular defects, such as isolated cranial nerve palsy. Normal velocity or even hyperfast saccadic eye movements in the presence of deficits of smooth pursuit have been well described in the literature in myasthenic patients. The reason for these paradoxical clinical findings has been reported to be due to increased postsynaptic folding of the fast-twitch fibers responsible for the execution of a saccade which is absent in those fibers responsible for slower, smooth eye movement. Saccadic characteristics therefore offer a point of differential diagnosis between patients suspected of having ocular motility deficits as a result of MG and those caused by other neuropathies. The advent of portable quantitative saccadic assessment means that previously laboratory-based assessments that require specialist equipment and training may now be undertaken clinically, providing a noninvasive test that can aid the differential diagnosis of the condition. The aim of this pilot study was to investigate the feasibility of the saccadometer (Ober Consulting, Poznan, Poland) in detecting the saccadic characteristics associated with myasthenia, specifically normal peak velocity (PV) in a group of patients confirmed with myasthenia.

METHODS

A group of 5 patients with a confirmed diagnosis of MG were recruited from a single site into the study along with 5 age-matched healthy volunteers. All myasthenic patients had ocular signs such as underaction or limitations of motility confirmed through ocular clinical examination. Healthy volunteers were screened for any underlying ocular motility or neurological defects before inclusion within the study. All participants undertook 100 trials of both 10 and 20° amplitude saccades, and mean PV, amplitude, and latency were recorded using the saccadometer for each individual. Overall, mean PV, amplitude, and latency were collated for both myasthenic and healthy control groups for each saccade size and compared.

RESULTS

The mean PV was significantly greater (481 ± 103.5 deg/seconds) for myasthenic patients compared with healthy controls (384 ± 42.8 deg/seconds) (P < 0.05) in 10° saccades. PV was also greater in myasthenics for 20° saccades; however, this difference did not reach statistical significance for patients with MG (547 ± 89.8 deg/seconds vs 477 ± 104.5 deg/seconds) (P = 0.14). The latency of participants with MG was not significantly different from those of age-matched healthy participants in 10° saccades but was significantly different for 20° saccades. There was no difference in amplitude measured between the groups.

CONCLUSIONS

PV for both 10 and 20° saccades was greater in myasthenic patients compared with healthy controls. All myasthenic patients produced normal velocity saccades in the presence of deficits of smooth ocular motility. The results from this small pilot study demonstrate the potential use of the saccadometer in a clinical setting to provide a noninvasive aid in the diagnosis of patients suspected with myasthenia.

Competitive endogenous RNA network and pathway-based analysis of LncRNA single-nucleotide polymorphism in myasthenia gravis

Myasthenia gravis (MG) is a complex neurological autoimmune disease with a pathogenetic mechanism that has yet to be elucidated. Emerging evidence has revealed that genes, non-coding RNAs and genetic variants play significant roles in the pathogenesis of MG. However, the molecular mechanisms of single nucleotide polymorphisms (SNPs) located on lncRNAs could disturb lncRNA-mediated ceRNA regulatory functions still unclear in MG. In this study, we collated 276 experimentally confirmed MG risk genes and 192 MG risk miRNAs. We then constructed a lncRNA-mediated ceRNA network for MG based on multi-step computational strategies. Next, we systematically integrated risk pathways and identified candidate SNPs in lncRNAs for MG based on data acquired from public databases. In addition, we constructed a pathway-based lncRNA-SNP mediated network (LSPN) that contained 128 lncRNAs targeting 8 MG risk pathways. By analyzing network, we propose a latent mechanism for how the “lncRNA-SNP-mRNA-pathway” axis affects the pathogenesis of MG. Moreover, 25 lncRNAs and 51 SNPs on lncRNAs were extracted from the “lncRNA-SNP-mRNA-pathway” axis. Finally, functional analyses demonstrated lncRNA-SNPs mediated ceRNA regulation pairs associated with MG participated in the MAPK signaling pathway. In summary, we constructed MG-specific lncRNA-SNPs mediated ceRNA regulatory networks based on pathway in the present study, which was helpful to elucidate the roles of lncRNA-SNPs in the pathogenesis of MG and provide novel insights into mechanism of lncRNA-SNPs as potential genetic risk biomarkers of MG.

Autoimmune autonomic ganglionopathy: Ganglionic acetylcholine receptor autoantibodies

Autoimmune Autonomic Ganglionopathy (AAG) is a rare immune-mediated disease of the autonomic nervous system. The incidence of AAG is unknown and diagnosis is often difficult due to the multicompartmental nature of the autonomic nervous system - sympathetic, parasympathetic and enteric components - with variable severity and number of components affected. Diagnostic confidence is increased when ganglionic acetylcholine receptor (gnACHR) autoantibodies are detected. Three gnACHR autoantibody diagnostic assays have been described (two binding assays, one receptor immunomodulation assay), but cross-validation between assays is limited. The prevalence of gnACHR autoantibodies in AAG is not known, with application of different clinical and laboratory criteria in the few studies of AAG cohorts and large retrospective laboratory studies of positive gnACHR autoantibodies lacking adequate clinical characterisation. Furthermore, the rate of unexpected gnACHR autoantibody positivity in conditions without overt autonomic dysfunction (false positive results) adds to the complexity of their interpretation. We review the pathophysiology of gnACHR autoantibodies and assays for their detection, with immunomodulation and high titer radioimmunoprecipitation results likely offering better AAG disease identification.

Effectiveness of thymectomy in juvenile myasthenia gravis and clinical characteristics associated with better outcomes

Thymectomy is an established treatment in adult myasthenia gravis, but its exact role in juvenile myasthenia gravis (JMG) is still uncertain. Thymectomy is frequently considered in the treatment of severe, medically refractory JMG. Surgical approaches have evolved from open median sternotomy to the more cosmesis-preserving thoracoscopic approach. This paper reviews current evidence on the effectiveness of thymectomy in JMG and discusses clinical characteristics which may be associated with improved outcomes. 17 studies including 588 patients who underwent thymectomy from 1997 to 2020 were found, which either reported uncontrolled cohorts undergoing thymectomy, or compared cohorts undergoing different surgical approaches. An improvement in clinical status or reduced requirement for medical therapy following thymectomy was seen in 453 patients (77%). Complete remission was seen in 40% (n = 172/430). Thoracoscopic approaches may provide improved outcomes, fewer complications, and better cosmetic outcomes. Better surgical outcomes may be associated with early intervention, intervention after the onset of puberty, being acetylcholine receptor antibody positive, having more severe disease and the presence of hyperplastic thymic tissue. However, analysis remains hindered by the limitations of the currently available retrospective studies of small cohorts. Nonetheless, available literature suggests a role for thymectomy in JMG patients, especially those with certain clinical characteristics.

Nemaline Myopathy: A Case Report

Generalized weakness in the pediatric and adolescent population is caused by many disorders that affect the neuromuscular axis. As next-generation sequencing (NGS) is becoming of high yield in replacing more invasive procedures, that is, muscle and nerve biopsy, more previously undiagnosed diseases of the muscles are now labeled with specific pathogenicity. A 16-year-old-girl diagnosed with nemaline myopathy but previously was misdiagnosed with congenital myasthenia and put-on unnecessary medications. Clinicians should be aware of congenital diseases that affect the muscles and know the importance of the NGS in reaching the correct diagnosis more so when there is a history of consanguinity.

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.

Clinical experience with maintenance therapeutic plasma exchange in refractory generalized myasthenia gravis

BACKGROUND

Despite the availability of several immunomodulatory therapies, about 20% of myasthenia gravis (MG) patients remain refractory to conventional treatments. There is limited evidence to support the use of maintenance therapeutic plasma exchange (TPE) therapy for refractory generalized MG.

METHODS

Retrospective chart review of 14 patients with refractory generalized MG treated for 12 months with maintenance TPE therapy. Outcome measures were myasthenia gravis composite (MGC) score, myasthenia gravis activities of daily living (MG-ADL), number of acute exacerbations, medication changes, and adverse events. Data were collected at 3 monthly intervals for 12 months before and after initiation of TPE therapy.

RESULTS

Clinically meaningful reductions in mean MG-ADL (>2 points) (mean MG-ADL score: 9.9 ± 0.5; 12-month pre-TPE to 5.2 ± 0.9; 12-month post-TPE) and MGC (>3 points) (mean MGC score: 25.2 ± 1.6; 12-month pre-TPE to 11.7 ± 1.4; 12-month post-TPE) were observed at 3 months following initiation of TPE and were maintained up to 12 months in all patients. After 12 months of TPE therapy, all patients had a significant reduction in daily prednisone and pyridostigmine use. Patients previously on IVIG or rituximab therapy were successfully weaned off both treatments. There was a significant reduction in acute MG exacerbations; 7.8 ± 1.1 mean exacerbations/patient (12-month pre-TPE) to 2 ± 1.1 mean exacerbations/patient (12-month post-TPE).

CONCLUSION

Over a period of 12 months, maintenance TPE therapy improved MG-ADL, and MGC with decreased immunosuppressant requirement, while being well-tolerated.

Zilucoplan: An Investigational Complement C5 Inhibitor for the Treatment of Acetylcholine Receptor Autoantibody-Positive Generalized Myasthenia Gravis

INTRODUCTION

Generalized myasthenia gravis (gMG) is an autoimmune disorder in which pathogenic autoantibodies damage the neuromuscular junction, causing disabling or life-threatening muscle weakness. Most treatments nonspecifically inhibit aspects of the immune system, do not directly address the causal mechanisms of tissue damage, and often have side-effect profiles that negatively impact patients. Understanding of the central pathogenic role of the complement cascade in gMG is advancing, and a new complement-targeting treatment is under investigation.

AREAS COVERED

We provide an overview of gMG etiology, the complement cascade, current treatments, and the investigational gMG therapy zilucoplan. Zilucoplan is a small, subcutaneously administered, macrocyclic peptide that inhibits cleavage of complement component C5 and the subsequent formation of the membrane attack complex.

EXPERT OPINION

In a randomized, double-blind, placebo-controlled, phase 2 clinical trial, zilucoplan demonstrated clinically meaningful complement inhibition in patients with acetylcholine receptor-positive gMG. Zilucoplan, a first-of-its-kind cyclic peptide targeting C5, appears to be a therapeutic option for the treatment of gMG based on available pharmacokinetic/pharmacodynamic data and phase 1 and 2 efficacy, safety, and tolerability data with limited long-term follow-up. Zilucoplan use earlier in the treatment paradigm would be suitable in this population should phase 3 efficacy and safety data be equally favorable.

Hemisensory loss in myasthenia gravis

A 73-year-old white man presents with left-sided ptosis and diplopia in the absence of ophthalmoplegia, with left hemibody paresthesia. He reports intermittent dysphagia and dizziness for 1 month and diarrhoea for 2 months. Serum and electrodiagnostic studies confirmed the diagnosis of myasthenia gravis. This case highlights the non-classic presentation of myasthenia gravis in the absence of ophthalmoplegia with a unique unexplained hemisensory deficit.

Neonatal Fc receptor in human immunity: Function and role in therapeutic intervention

The humoral immune response provides specific, long-lived protection against invading pathogens, via immunoglobulin production and other memory functions. IgG, the most abundant immunoglobulin isotype, has the longest half-life and protects against bacterial and viral infections. The neonatal Fc receptor (FcRn) transports IgG across barriers, for example, the placenta, enhancing fetal humoral immunity to levels similar to their mothers'. Importantly, FcRn, by protecting IgG from intracellular degradation, results in an approximately 21-day circulating IgG half-life and high plasma levels; similarly, FcRn recycles albumin and is the portal of entry for enteric cytopathic human orphan (echo) virus infection. Dysregulated immune responses may lead to antibodies against self-antigens (autoantibodies), resulting in organ-specific or systemic autoimmune diseases. Autoantibody-mediated diseases have been treated by nonspecific immunoglobulin-lowering/modulating therapies, including immunoadsorption, plasma exchange, and high-dose intravenous immunoglobulin. However, targeting FcRn with specific inhibitors results in reduction in only IgG levels. The effectiveness of FcRn inhibitors in autoimmune diseases, including myasthenia gravis and immune thrombocytopenia, provides further evidence that IgG is a primary driver in these autoantibody-mediated diseases. We describe the role of FcRn in human biology, including insights that clinical testing of FcRn inhibitors have provided into FcRn biology and autoimmune disease mechanisms, allowing fact-based speculation on their therapeutic potential.

Clinical Experience with Eculizumab in Treatment-Refractory Acetylcholine Receptor Antibody-Positive Generalized Myasthenia Gravis

Background:

Although established therapies are effective in most patients with generalized myasthenia gravis (gMG), some patients do not respond or they experience intolerable adverse events, highlighting the need for better tolerated, targeted therapies for treatment-refractory gMG.

Objective:

To describe real-world experience with eculizumab in patients with treatment-refractory acetylcholine receptor antibody-positive (AChR+) gMG.

Methods:

Retrospective chart review of 15 patients with treatment-refractory AChR+ gMG treated for 12 months with eculizumab (900 mg/week for 4 weeks then 1200 mg every 2 weeks). Outcome measures were Myasthenia Gravis–Activities of Daily Living (MG-ADL) scores, number of exacerbations, single-breath count test (SBCT) score, medication changes, selected Quantitative Myasthenia Gravis (QMG) evaluations, and adverse events. Data collected at 3-monthly intervals for 12 months before and after eculizumab initiation were analyzed.

Results:

Clinically meaningful reductions in total MG-ADL scores were observed at 3 months following eculizumab initiation and maintained up to 12 months in all patients. After 12 months’ eculizumab treatment, there was a significant reduction in the number of acute exacerbations; mean (SD) SBCT score improved from 28.13 (0.33) to 50.26 (2.86); all patients achieved a ‘none’ or ‘mild’ rating for QMG evaluations; all patients reduced their daily prednisone dose; and nine patients had discontinued pyridostigmine. At the end of treatment, intravenous immunoglobulin was discontinued in all six patients receiving this therapy at eculizumab initiation. Eculizumab was well tolerated.

Conclusions:

This real-world study demonstrated improvement in outcome measures and decreased concomitant drug requirement within 12 months of eculizumab initiation in patients with treatment-refractory AChR+ gMG.

Pronounced Ptosis in Myasthenia Gravis-A New Bedside Clinical Sign

We report three cases of myasthenia gravis in whom the asymmetrical ptosis at presentation became more pronounced with the described bedside technique. Pronounced ptosis could be elicited by making the patient speak continuously for up to 2 minutes. Pauses for breathing and natural blinking were allowed. The sign is best elicited in newly diagnosed and treatment-naive patients. The loss of compensation for ptosis by frontalis muscle due to speech-induced fatigue may be responsible for the observed effect. Patients’ symptoms abated on treatment with acetylcholine esterase inhibitors, steroids, and steroid-sparing agents.

Myasthenia gravis presenting as bilateral pseudointernuclear ophthalmoplegia in a patient with an incidental prolactinoma

Myasthenia gravis (MG) is a rare and potentially dangerous autoimmune condition, which affects the acetylcholine receptors at the neuromuscular junction of skeletal muscle. MG's diverse symptomatology may readily masquerade as other neurological conditions, posing a diagnostic challenge to clinicians. We describe a 24-year old man who presented to the emergency department with a new onset internuclear ophthalmoplegia. After a series of investigations, we eventually arrived at a diagnosis of MG with pseudointernuclear ophthalmoplegia with an incidentally detected prolactinoma. We explore the literature regarding the pathophysiology of pseudointernuclear ophthalmoplegia, the link between prolactin and autoimmunity and the association between prolactinoma and MG.

Prediction of generalization of ocular myasthenia gravis under immunosuppressive therapy in Northwest China

BACKGROUND

It is well demonstrated that immunosuppressants can reduce, but not eliminate the risk of generalized development in ocular myasthenia gravis (OMG). In this study, we aimed to explore the predictive factors of generalized conversion of OMG patients who received immunosuppressive treatments.

METHODS

OMG patients under immunosuppressive treatments in Tangdu Hospital from June 2008 to June 2012 were retrospectively reviewed. Baseline clinical characteristics were documented. Patients were followed up regularly by face-to-face interview and the main outcome measure was generalized conversion. The logistic regression analysis was performed to determine the predictive factors of generalization of OMG.

RESULTS

Two hundred twenty-three eligible OMG patients completed the final follow-up visit and 38 (17.0%) progressed to generalized MG (GMG) at a median time to generalization of 0.9 year. Patients with adult onset and positive repetitive nerve stimulation (RNS) of facial or axillary nerve had higher conversion rate than those with juvenile onset and negative RNS (p = 0.001; p = 0.019; p = 0.015, respectively). Adult-onset patients converted earlier than juvenile-onset OMG patients (p = 0.014). Upon multivariate logistic regression analysis, age of onset (Odds ratio [OR] 1.023, 95% confidence interval [CI] 1.006-1.041, p = 0.007) and positive facial nerve RNS (OR 2.826, 95%CI 1.045-5.460, p = 0.038) were found to be positively associated with generalized development. Moreover, an obviously negative association was found for disease duration (OR 0.603, 95%CI 0.365-0.850, p = 0.019).

CONCLUSIONS

Age of onset, disease duration and facial nerve RNS test can predict generalized conversion of OMG under immunosuppressive therapy. Adult-onset, shorter disease duration and facial nerve RNS-positive OMG patients have a higher risk of generalized development.

Successful Transition from Plasma Exchange to Eculizumab in Acetylcholine Receptor Antibody- and Muscle-Specific Kinase (MuSK) Antibody-Negative Myasthenia Gravis: A Case Report

BACKGROUND The effectiveness of eculizumab (a terminal complement inhibitor) in acetylcholine receptor (AChR) antibody-negative generalized myasthenia gravis (gMG) is unknown. CASE REPORT A female patient was diagnosed with AChR-antibody and muscle-specific kinase (MuSK) antibody-negative gMG in March 2016. In January 2017, the patient was referred for plasma exchange (PLEX) because of continuing symptoms. She was also receiving azathioprine, mycophenolate mofetil, and pyridostigmine (all were continued during subsequent therapies). PLEX (5 sessions over 10 days) was initially effective, but over the following month the patient received PLEX weekly, then twice weekly, followed by 3-times weekly because of worsening symptoms. In April 2018, PLEX was reduced to twice weekly following initiation of eculizumab (weekly induction dose of 900 mg 1 day after first PLEX, plus 600 mg on the day of the second PLEX session, for 4 weeks). The patient was then stabilized on eculizumab 1200 mg every 2 weeks and the frequency of PLEX treatment was reduced, until PLEX was discontinued at Week 39 after eculizumab initiation. During eculizumab treatment, the patient's myasthenia gravis activities of daily living (MG-ADL) score decreased from 9 to 1 or 2 at most assessments, with a transient increase to 4 or 5 between Weeks 19 and 27 following less frequent eculizumab treatment. There were no eculizumab-related adverse events. CONCLUSIONS Following transition from 3-times weekly PLEX to eculizumab in a patient with treatment-refractory, AChR antibody- and MuSK antibody-negative gMG, there were clinically significant improvements in everyday activities affected by MG symptoms. Further investigation of eculizumab in antibody-negative MG is required.

Understanding side effects of therapy for myasthenia gravis and their impact on daily life

Background

Myasthenia gravis is a chronic, autoimmune, neuromuscular junction disorder characterized by skeletal muscle weakness. Current therapies for myasthenia gravis are associated with significant side effects. The objective of this study was to characterize the side effects, and associated health-related quality of life and treatment impacts, of traditional myasthenia gravis treatments.

Methods

This study had two phases; a Phase 1 interview and a 2-part web-based survey in Phase 2 that included brainstorming (Step 1) and rating (Step 2) exercises using group concept mapping. In Phase 1, all 14 participants reported experiencing side effects from myasthenia gravis treatments which had significant impacts on daily life. In Phase 2, 246 participants contributed to Step 1; 158 returned for Step 2.

Results

The brainstorming exercise produced 874 statements about side effects and their impact, which were reduced to 35 side effects and 23 impact-on-daily life statements. When rating these statements on severity, frequency, and tolerability, blood clots, infections/decreased immunity, weight gain, and diarrhea were the least tolerable and most severely rated. The most frequent and severe impacts were sleep interference and reduced physical and social activities.

Conclusions

Based on these findings, there appears to be a need for better and more tolerable treatments for myasthenia gravis patients.

Concurrence of Myasthenia Gravis and Thyroid Disorders: A Retrospective Database Study

Introduction

Both myasthenia gravis (MG) and autoimmune thyroid diseases (AITDs) are autoimmune diseases. Graves’disease (GD) is the most common AITD reported to be associated with MG. Currently, there is limited data on prevalence and clinical features/outcomes of MG in various thyroid diseases in a large database report.

Methodology

A total of 872 patients with MG and 97,251 patients with thyroid disorders had been recorded by the tertiary hospital database. The study period was between 1997 and 2017. Patients with a thyroid disorder and MG were identified by the ICD-10-CM code. Clinical courses of MG accompanied by thyroid disorders were studied.

Results

During the 20-year study period, there were 872 patients with MG and 97,251 patients with thyroid disorders. In the group with thyroid disorders, 28,886 patients (29.70%) had GD, 1,612 patients (1.66%) had Hashimoto's thyroiditis (HT), 13,172 patients (13.54%) had toxic goiter and 53,581 patients (55.10%) had nontoxic goiter. Ninety-seven patients had been diagnosed with both MG and thyroid disorders. Among the four types of thyroid disorders, the rate of MG was highest in HT group (9.92/1,000 HT patients). There were four significant factors among four groups of thyroid disorders including age of onset of thyroid disease (p 0.004), MG classification (p<0.001), MG treatment (p<0.001), and thymic pathology (p 0.034). Among the four groups of thyroid disorders, patients with MG and HT were diagnosed with thyroid disease at the youngest age (27 years) compared with other thyroid diseases. Additionally, the MG patients with HT also had the highest proportion of MG class 4-5 a/b (7 patients, 43.75%), received prednisolone treatment (15 patients, 93.75%), received immunosuppressants (9 patients, 56.25%), received IVIG or PLEX (5 patients, 31.30%), and had thymoma (6 patients, 46.15%).

Conclusion

MG is most prevalent in patients with HT. Patients with both MG and HT had more severe MG status and had higher rate of thymoma.

Autoimmune Polyendocrinopathy

CONTEXT

This mini-review offers an update on the rare autoimmune polyendocrinopathy (AP) syndrome with a synopsis of recent developments.

DESIGN AND RESULTS

Systematic search for studies related to pathogenesis, immunogenetics, screening, diagnosis, clinical spectrum, and epidemiology of AP. AP (orphan code ORPHA 282196) is defined as the autoimmune-induced failure of at least two glands. AP is divided into the rare juvenile type I and the adult types II to IV. The prevalence is 1:100,000 and 1:20,000 for types I and types II to IV, respectively. Whereas type I (ORPHA 3453) is a monogenetic syndrome with an autosomal recessive transmission related to mutations in the autoimmune regulator (AIRE) gene, types II to IV are genetically complex multifactorial syndromes that are strongly associated with certain alleles of HLA genes within the major histocompatibility complex located on chromosome 6, as well as the cytotoxic T lymphocyte antigen 4 and the protein tyrosine phosphatase nonreceptor type 22 genes. Addison disease is the major endocrine component of type II (ORPHA 3143), whereas the coexistence of type 1 diabetes and autoimmune thyroid disease is characteristic for type III (ORPHA 227982). Genetic screening for the AIRE gene is useful in patients with suspected type I, whereas serological screening (i.e., diabetes/adrenal antibodies) is required in patients with monoglandular autoimmunity and suspected AP. If positive, functional endocrine testing of the antibody-positive patients as well as serological screening of their first-degree relatives is recommended.

CONCLUSION

Timely diagnosis, genetic counseling, and optimal long-term management of AP is best offered in specialized centers.

Generalized Myasthenia Gravis: Classification, Clinical Presentation, Natural History, and Epidemiology

Myasthenia gravis (MG) is a rare disease, but the most common disorder of the neuromuscular junction. It is the prototypic autoimmune disease most commonly caused by antibodies to the acetylcholine receptor (AChR) leading to characteristic fatigable weakness of the ocular, bulbar, respiratory, axial, and limb muscles. The majority of patients with MG first present with ocular symptoms. Most patients with MG will experience at least 1 exacerbation of symptoms throughout the course of their illness. This article will cover the epidemiology, clinical presentation, classification, and natural history of MG.

Laboratory Evaluation of Spasmodic Dysphonia

OBJECTIVES

To evaluate the utility of comprehensive laboratory evaluation in patients with spasmodic dysphonia (SD).

STUDY DESIGN

Retrospective chart review.

METHODS

A review of the medical records of 40 patients diagnosed with spasmodic dysphonia from 2009-2018 was preformed to evaluate abnormal test results that were significant when compared with abnormal results of the general population and for any other clinically relevant pathology.

RESULTS

Erythrocyte sedimentation rate, ceruloplasmin levels, and anti-AChR were found to be elevated at levels considered statistically significant (p <0.05). Furthermore, we found levels of cholesterol, thyroid-stimulating hormone (TSH), T3, fasting blood glucose, creatine kinase, immunoglobulin, antinuclear antibody (ANA), and alpha-fetoprotein (AFP) levels to be abnormal at a greater rate in our population, but these were not statistically significant. Workup revealed several underlying conditions including thyroid neoplasms, hypothyroidism, and laryngopharyngeal reflux. Additionally, brain MRI revealed age-related ischemic pathology in an elevated number of patients, but with no obvious clinical sequalae.

CONCLUSION

There is an association between serological values and spasmodic dysphonia that can aid in diagnosing pathology, as well as establishing a directed workup. Additionally, our study shows the utility of comprehensive evaluation in identifying undetected disease.

Clinical analysis of Chinese anti-low-density-lipoprotein-receptor-associated protein 4 antibodies in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Low-density-lipoprotein-receptor-associated protein 4 (LRP4) autoantibodies have recently been detected in myasthenia gravis (MG), but little is known about the clinical characteristics associated with this serological type. In this study, the clinical features of Chinese patients with anti-LRP4 antibody-positive MG were characterized.

METHODS

A total of 2172 MG serum samples were collected from patients in various parts of China. An enzyme-linked immunosorbent assay was used to detect acetylcholine receptor (AChR) antibody and titin antibody, and cell-based assays were used to detect muscle-specific kinase antibody and LRP4 antibody. Clinical data for patients with MG were collected from different provinces in China.

RESULTS

In total, 16 (0.8%) patients with LRP4-MG were found amongst 2172 total patients, including three patients with AChR/LRP4-MG. Additionally, 13 (2.9%) patients with LRP4-MG were found amongst 455 patients with double seronegative MG. The ratio of males to females for these 13 patients was 1:1.6, and 53.8% patients were children. A total of 91.7% of cases exhibited initial ocular involvement, and 58.3% of cases exhibited simple eye muscle involvement. Responses to acetylcholinesterase inhibitors and prednisone were observed.

CONCLUSION

The expanded sample confirmed that the positive rate of LRP4 antibodies in China is lower than that in western countries. Our results highlighted the differences between LRP4-MG and other antibody groups. Children and female patients with LRP4-MG have a higher prevalence, often involving the ocular muscles and limb muscles. The clinical symptoms are mild, and satisfactory responses to treatment are often achieved.

Hypophonia as only presenting symptom in myasthenia gravis - a diagnostic dilemma in poor countries: a case report

INTRODUCTION

The autoimmune disease myasthenia gravis can mimic a variety of neurological disorders leading to a delay in diagnosis and treatment. In the older population, due to confusion with signs of the ageing process or comorbidities due to ageing, there are many underdiagnosed or misdiagnosed cases of myasthenia gravis. A majority of myasthenia gravis symptoms appear as ocular or motor symptoms and there are very few cases of bulbar symptoms. We present a case of myasthenia gravis with only hypophonia as a clinical feature.

CASE PRESENTATION

We present a case of a 51-year-old Madheshi woman whose only complaint was sudden onset of hypophonia which later showed a fluctuating nature throughout the daytime. There was only reduced pitch in her voice with no nasal tone or dysarthria (so-called dysphonia), which created a diagnostic dilemma. Later, a neurological examination and other relevant investigations suggested myasthenia gravis.

CONCLUSIONS

Sudden onset and focal neurological deficit can raise the diagnostic dilemma of myasthenia gravis. Relevant laboratory tests and clinical examinations are important to diagnose this disease properly. In resources-deprived nations like Nepal, where several investigations are expensive and access to them is difficult, it becomes very difficult to achieve a solid diagnosis for rare presentations of diseases.

The long noncoding RNA MALAT-1 functions as a competing endogenous RNA to regulate MSL2 expression by sponging miR-338-3p in myasthenia gravis

Myasthenia gravis (MG) is a cell-dependent autoimmune disease commonly associated with thymic pathology. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) has been associated with gene regulation and alternative splicing. It has shown relationship with proliferation, apoptosis, migration, and invasion. In this study, we found that MALAT-1 expression was downregulated in MG. The level of the miR-338-3p was increased in peripheral blood mononuclear cells from MG patients compared with those from control subjects. MALAT-1 competed for binding to miR-338-3p with male-specific lethal 2 (MSL2) in luciferase reporter assays. We confirmed the MALAT-1-miR-338-3p-MSL2 interaction network in MG in vitro. Thus, MALAT-1 directly induced MSL2 expression in MG by acting as a competing endogenous RNA for miR-338-3p, suggesting that it may serve as a therapeutic target for MG treatment.

Misdiagnosis of myasthenia gravis presenting with tongue and palatal weakness

We discuss the case of an elderly male who presented with a history of dysphagia, dysphonia, palatal weakness and a sensation of tongue swelling, each symptom of varying time duration. Myasthenia gravis may have a variety of presentations that include ocular fatigability, respiratory muscle weakness and bulbar symptoms. The variety of these myasthenic syndromes can serve as a barrier to diagnosis and can often result in delayed or incorrect diagnosis. In this report, we present an atypical presentation of a relatively rare condition.

Ocular vestibular evoked myogenic potential in patients with myasthenia gravis: A prospective clinical study

OBJECTIVE

Myasthenia gravis (MG) is an archetypic disorder of neuromuscular junctions (NMJs) and autoantibody-mediated disease causing fatigable weakness of skeletal muscles with an ocular onset in up to 85%. The aim of this study was to detect extra ocular muscles (EOMs) abnormalities in MG patients using ocular vestibular evoked myogenic potential (oVEMP) n10 response.

METHODS

The oVEMP was performed on 40 myasthenia gravis patients that were divided into three groups: newly diagnosed (10 patients), uncontrolled on treatment (15 patients) and controlled on treatment (15 patients) groups in addition to a control group of 10 subjects. Also a comparison of oVEMP response was held between patients with generalized and ocular MG.

RESULTS

The oVEMP n10 showed significant difference between the 3 study groups and the control. The n10 showed no significant difference between the newly diagnosed group and the other 2 groups. There was also significant difference between uncontrolled and controlled on treatment group and between generalized and ocular types of myasthenic patients.

CONCLUSION

The oVEMP can be usefully used in diagnosis of new MG patients as regard n10 amplitude, threshold and AR except n10 latency with no therapeutic or monitoring value of oVEMP in MG.

Acetylcholine receptor antibody-positive myasthenia gravis associated with small-cell lung cancer: A case report

RATIONALE

Only few cases of myasthenia gravis (MG) associated with small-cell lung cancer (SCLC) have been reported, and cases positive for acetylcholine receptor antibody (AChR-ab) are even rarer. The efficacy of standard MG treatment, such as cholinesterase inhibitor therapy, immunosuppressive therapy using steroids and immunosuppressive drugs, plasma exchange, and intravenous immune globulin (IVIg), for these cases is unclear.

PATIENT CONCERNS AND DIAGNOSES

A 71-year-old man complained of bilateral eyelid ptosis. He also presented with dysphagia and masticatory muscle fatigue after chewing. The edrophonium test was positive, and the serum AChR-ab level was increased; therefore, the patient was diagnosed with MG. Computed tomography scan showed a nodule on the left upper lobe of the lung and mediastinal lymphadenopathy. Further examination revealed the lesion as SCLC. Finally, he was diagnosed with AChR-ab-positive MG associated with SCLC.

INTERVENTIONS AND OUTCOMES

Oral pyridostigmine and tacrolimus were administered to treat MG; however, his symptoms worsened. Therefore, methylprednisolone and IVIg were administrated, which temporarily improved his symptoms. However, they remained uncontrolled. Meanwhile, chemotherapy with carboplatin and etoposide was administered to treat his SCLC. The lesions shrunk, and the MG symptoms and serum AChR-ab level also improved.

LESSONS

AChR-ab-positive MG may develop as a comorbidity of SCLC. In such cases, management might require treatment for SCLC in addition to the standard MG treatment to stabilize the MG symptoms.

Myasthenia Gravis and Associated Diseases

BACKGROUND:

Myasthenia gravis (MG) is an autoimmune disease caused by the action of specific antibodies to the postsynaptic membrane of the neuromuscular junction, leading to impaired neuromuscular transmission. Patients with MG have an increased incidence of other autoimmune diseases.

AIM:

to determine the presence of other associated diseases in patients with MG.

METHOD:

A group of 127 patients with MG followed in 10 years period, in which the presence of other associated diseases has been analysed.

RESULTS:

The sex ratio is in favour of the female sex, the average age of the initial manifestation of the disease is less than 50 years, 65.4% of the patients with MG have another disease. 15.0% patients have associated another autoimmune disease. Thyroid disease is the most common associated with MG, rarely rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and other autoimmune diseases. Other diseases include hypertension, heart disease, diabetes, respiratory diseases, dyslipidemia. 10.2% of the patients are diagnosed with extrathymic tumours of various origins.

CONCLUSION:

Associated diseases are common in patients with MG, drawing attention to the possible common basis for their coexistence, as well as their impact on the intensity and treatment of the disease.

Early onset bilateral juvenile myasthenia gravis masquerading as simple congenital ptosis

Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction. Ocular myasthenia gravis presents as ptosis with extraocular motility restriction and is prone to be misdiagnosed as third nerve palsy or congenital or aponeurotic ptosis. Juvenile ocular myasthenia gravis in very young children is difficult to diagnose and can be easily labeled as a case of congenital ptosis, the more so when the condition is bilateral. We present a case of a two-year-old child who presented with bilateral ptosis and was diagnosed as a case of simple congenital ptosis elsewhere with the advice to undergo tarsofrontalis sling surgery. The child was diagnosed with juvenile myasthenia gravis on thorough history, examination, and systemic evaluation and was started on anti-myasthenic treatment.