Myasthenic crisis: guidelines for prevention and treatment

Frequency and Severity of Myasthenia Gravis Exacerbations Associated With the Use of Ciprofloxacin, Levofloxacin, and Azithromycin

INTRODUCTION/AIMS

The true frequency and severity of myasthenia gravis (MG) exacerbation associated with the usage of fluoroquinolone and macrolide antibiotics remain unknown. We aimed to investigate the association between ciprofloxacin, levofloxacin, azithromycin, and MG exacerbation.

METHODS

A retrospective review was performed on MG patients seen at a single institution between 2002 and 2022, who received ciprofloxacin, levofloxacin, or azithromycin. Amoxicillin usage was chosen for comparison. The strength of association between antibiotic usage and MG exacerbation was scored using the Adverse Drug Reactions Probability Scale. A mixed-effects logistic regression model was constructed to evaluate predictors of antibiotic-associated MG exacerbation (AAMGE).

RESULTS

365 patients had a total of 918 episodes of antibiotic usage (n = 339 for ciprofloxacin, n = 187 for levofloxacin, n = 392 for azithromycin). Frequencies of MG exacerbation following antibiotic use were: 8 (2.4%) for ciprofloxacin, 3 (1.6%) for levofloxacin, 6 (1.5%) for azithromycin, and 17 (1.9%) for all. Six patients had impending crisis/crisis, and 9 required rescue therapy. MG exacerbation was associated with MG-related hospitalization or ED visit in the preceding 6 months (p = 0.012), female sex (p = 0.023) and diabetes (p = 0.032). Infection was the most common confounder in exacerbations (88.2%). MG exacerbation was seen in 8/603 (1.3%) episodes of amoxicillin use, without a significant difference in frequencies of AAMGE among the four antibiotics (p = 0.68).

DISCUSSION

Usage of ciprofloxacin, levofloxacin, or azithromycin was associated with MG exacerbation in less than 2.5% of episodes of antibiotic use. Underlying infection may play a role in AAMGE. As AAMGE can be severe, decision-making regarding the use of these antibiotics should be individualized.

Racial disparities in acute care utilization among individuals with myasthenia gravis

Objective

In myasthenia gravis (MG), evidence on the impact of social determinants of health on disparities in disease burden and healthcare resource utilization is limited. This study aimed to investigate the independent association between race/ethnicity and acute care utilization during the 2 years post-diagnosis among patients with MG.

Methods

A retrospective cohort study was conducted among adults (≥18 years) with newly diagnosed MG in the United States using Optum's de-identified Market Clarity Data from January 1, 2010, to December 31, 2019. Multivariable regression models were used to assess the association between acute care utilization and race/ethnicity, insurance, exacerbation at index, and other covariates.

Results

A total of 7,058 patients met the study inclusion criteria, of whom 57% (n = 4,052) identified as Caucasian, 6% (n = 445) African American, 3% (n = 235) Hispanic, 1% (n = 94) Asian, and 32% (n = 2,232) with missing race/ethnicity information. Compared with patients identifying as Caucasian, those identifying as African American had 37% higher odds of having an emergency department visit in year 1, and those identifying as Hispanic had 70% increase in odds of having a hospitalization event in year 2 post-diagnosis. Among other covariates, Medicaid usage, exacerbation at index, and number of outpatient visits were significantly associated with acute care utilization.

Conclusion

Racial disparities significantly impacted acute care utilization in the first 2 years post-MG diagnosis. Future studies should aim to examine specific factors that may contribute to disparities such as barriers to healthcare access, greater severity of MG symptoms, and poorly controlled disease.

Data-driven explainable machine learning for personalized risk classification of myasthenic crisis

OBJECTIVE

Myasthenic crisis (MC) is a critical progression of Myasthenia gravis (MG), requiring intensive care treatment and invasive therapies. Classifying patients at high-risk for MC facilitates treatment decisions such as changes in medication or the need for mechanical ventilation and helps prevent disease progression by decreasing treatment-induced stress on the patient. Here, we investigated whether it is possible to reliably classify MG patients into groups at low or high risk of MC based entirely on routine medical data using explainable machine learning (ML).

METHODS

In this single-center pseudo-prospective cohort study, we investigated the precision of ML models trained with real-world routine clinical data to identify MG patients at risk for MC, and identified explainable distinctive features for the groups. 51 MG patients, including 13 MC, were used for model training based on real-world clinical data available from the hospital management system. Patients were classified to high or low risk for MC using Lasso regression or random forest ML models.

RESULTS

The mean cross-validated AUC classifying MG patients as high or low risk for MC based on simple or compound features derived from real-world clinical data showed a predictive accuracy of 68.8% for a regularized Lasso regression and 76.5% for a random forest model. Studying feature importance across 5100 model runs identified explainable features to distinguish MG patients at high or low risk for MC. Feature importance scores suggested that multimorbidity may play a role in risk classification.

CONCLUSION

This study establishes feasibility and proof-of-concept for risk classification of MC based on real-world routine clinical data using ML with explainable features and variance control at the point of care. Future research on ML-based prediction of MC should include multi-center, multinational data collection, more in-depth data per patient, more patients, and an attention-based ML model to include free-text.

Intensive care due to myasthenia gravis: Risk factors and prognosis

BACKGROUND AND PURPOSE

Exacerbation of myasthenia gravis (MG) with respiratory failure requires intensive care. We aimed to study the risk factors for intensive care unit admission for MG exacerbation and myasthenic crisis (MC) and the prognosis of people with MG (pwMG) thereafter.

METHODS

This retrospective study investigated patients in the Helsinki and Uusimaa hospital district during the years 2008-2021. PwMG (International Classification of Diseases, 10th revision code G70.0) were identified through a data repository search, followed by a chart review of patient records. Risk factors for intensive care due to MG exacerbation were evaluated as compared with the patients only treated in the outpatient clinic and those treated in the neurological ward for MG exacerbation. The outcomes of patients in intensive care for any reason were also compared with those of patients in intensive care for exacerbation of bronchial asthma.

RESULTS

Of 577 pwMG, 35 (6.1%) needed intensive care for MG within a median of 5.3 months from diagnosis. The mean (±SD) age at MG diagnosis was higher in the intensive care group (60.5 [±16.1] years) compared to the outpatient (48.3 [±20.9] years; p < 0.001) and neurological ward groups (53.4 [±20.8] years; p = 0.044). Thymoma (odds ratio [OR] 4.8, 95% confidence interval [CI] 1.19-19.43; p = 0.028) and female sex (OR 2.1, 95% CI 1.02-4.48; p = 0.045) were independent risk factors for intensive care. In-hospital mortality was 4% for MC patients. Six-month mortality after intensive care for MG exacerbation (14.3%) was twice that for asthma exacerbation (7.7%).

CONCLUSION

Our study shows an increased risk of intensive care treatment for patients with late-onset MG, female sex or thymoma, occurring usually within 6 months from diagnosis, which emphasises the importance of early treatment choices.

Activity Prediction Modeling Based on a Combination of Growth Differentiation Factor 15 and Serum Biomarker Levels in Dermatomyositis and Polymyositis

AIMS

Growth differentiation factor 15 (GDF15) plays an important role in multiple inflammatory disorders. We aimed to analyze serum GDF15 levels in adult patients with idiopathic inflammatory myopathies (IIMs).

METHODS

Serum GDF15 levels were measured in 179 adult patients with IIMs and 76 healthy controls (HCs). The association between GDF15 levels and disease variables was analyzed using Spearman's rank correlation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory ability of GDF15 and the GDF15-to-lymphocyte ratio (GLR). Machine learning methods were applied to build predictive models.

RESULTS

GDF15 levels and GLR were significantly elevated in patients with adult IIMs than in HCs. Compared with patients in remission, both GDF15 and GLR were significantly higher in myositis patients in an active phase. GDF15 levels correlated positively with myositis disease activity indices and negatively correlated with lymphocyte and platelet counts. ROC curve analysis revealed that GDF15 levels and GLR outperformed muscle enzymes and distinguished well between patients with active disease and those in remission. Furthermore, even in the normal muscle enzyme group, GDF15 levels and GLR were also well-distinguished between patients with active disease and those in remission. Using machine learning, a logistic regression model of GDF15 combined with creatine kinase and lymphocyte count was constructed and had a reliable predictive value for disease activity.

CONCLUSIONS

GDF15, particularly GLR, was significantly correlated with disease activity in adult patients with IIMs. They could serve as useful biochemical markers for evaluating disease activity, monitoring disease progression, and guiding treatment in adult patients with IIMs.

Comparative Analysis of Intravenous Immunoglobulins (IVIg) vs Plasmapheresis (PLEX) in the Management of Myasthenic Crisis

Myasthenia gravis (MG) is an autoimmune disorder affecting postsynaptic membranes in neuromuscular junctions, presenting as fatigable muscle weakness. Myasthenic crisis is a life-threatening complication characterized by severe respiratory insufficiency necessitating invasive or noninvasive ventilation. Two rapid therapies used to manage myasthenic crises are intravenous immunoglobulins (IVIg) and plasmapheresis (PLEX). Their comparative effectiveness remains equivocal. Our article examines evidence from several clinical trials and observational studies, in order to determine the superiority of one treatment over the other. Multiple factors can complicate the choices between two treatments. We concluded that the choice between PLEX and IVIg is multifaceted, guided by individual patient characteristics, institutional resources, and clinician preference. While PLEX can be considered as first-line for rapid clinical outcomes, it is hard to pick one treatment over the other, and careful consideration of comorbidities and resource availability is crucial. Our article highlights the need for further research to establish definitive guidelines and enhance patient outcomes in myasthenic crisis patients.

Seronegative Myasthenia Gravis: A Rare Disease Triggered by SARS-CoV-2 or a Coincidence?

Myasthenia gravis (MG) results from the production of autoantibodies against the neuromuscular junction, leading to muscle weakness. Although the exact cause is not fully understood, it is known that the onset and exacerbations of MG can occur after viral infections. We present the case of a patient with no prior history of MG with new-onset proximal muscle weakness and ptosis, following SARS-CoV-2 infection, This case underscores the potential for autoimmune diseases to be triggered by SARS-CoV-2.

Acute Respiratory Failure Due to Inaugural Myasthenia Crisis

Myasthenia gravis is a rare disease that can lead to a serious condition known as myasthenic crisis (MC). The diagnosis of MC is clinical and relies on the presence of typical symptoms that can be absent, emphasizing the importance of attracting the attention of emergency physicians to this rare cause of respiratory failure. We present the case of a 66-year-old woman presenting to the emergency department with a history of recent muscle fatigue and dehydration who developed acute respiratory failure requiring mechanical ventilation.

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.

Myasthenia Gravis Presenting as Bulbar Palsy

Myasthenia gravis is a rare autoimmune condition that affects postsynaptic cholinergic receptors, resulting in symptoms of muscular fatigue. Clinical signs could be subtle and variable, often leading to many differentials. This leads to inappropriate tests being performed and a delay in diagnosis. Although ocular signs are more common, it may rarely present as bulbar palsy. Our patient, in her 30s, was referred to the emergency department after six months of symptom onset when she was discovered to be at a high risk of silent aspiration. Her presentation was predominantly bulbar palsy, but after appropriate tests, she was eventually diagnosed with generalized myasthenia gravis with a concurrent thymoma. Her treatment included pyridostigmine, corticosteroid, and immunoglobulins, while a thymectomy was scheduled as a planned procedure. Prompt diagnosis and timely management can reduce morbidity and mortality in such cases.

Assessing facial weakness in myasthenia gravis with facial recognition software and deep learning

OBJECTIVE

Myasthenia gravis (MG) is an autoimmune disease leading to fatigable muscle weakness. Extra-ocular and bulbar muscles are most commonly affected. We aimed to investigate whether facial weakness can be quantified automatically and used for diagnosis and disease monitoring.

METHODS

In this cross-sectional study, we analyzed video recordings of 70 MG patients and 69 healthy controls (HC) with two different methods. Facial weakness was first quantified with facial expression recognition software. Subsequently, a deep learning (DL) computer model was trained for the classification of diagnosis and disease severity using multiple cross-validations on videos of 50 patients and 50 controls. Results were validated using unseen videos of 20 MG patients and 19 HC.

RESULTS

Expression of anger (p = 0.026), fear (p = 0.003), and happiness (p < 0.001) was significantly decreased in MG compared to HC. Specific patterns of decreased facial movement were detectable in each emotion. Results of the DL model for diagnosis were as follows: area under the curve (AUC) of the receiver operator curve 0.75 (95% CI 0.65-0.85), sensitivity 0.76, specificity 0.76, and accuracy 76%. For disease severity: AUC 0.75 (95% CI 0.60-0.90), sensitivity 0.93, specificity 0.63, and accuracy 80%. Results of validation, diagnosis: AUC 0.82 (95% CI: 0.67-0.97), sensitivity 1.0, specificity 0.74, and accuracy 87%. For disease severity: AUC 0.88 (95% CI: 0.67-1.0), sensitivity 1.0, specificity 0.86, and accuracy 94%.

INTERPRETATION

Patterns of facial weakness can be detected with facial recognition software. Second, this study delivers a 'proof of concept' for a DL model that can distinguish MG from HC and classifies disease severity.

Single count breath test for the evaluation of respiratory function in Myasthenia Gravis: A systematic review

BACKGROUND

Myasthenia gravis (MG) can have a variety of respiratory presentations, ranging from mild symptoms through to respiratory failure. The evaluation of respiratory function in MG can be limited by accessibility to testing facilities, availability of medical equipment, and facial weakness. The single count breath test (SCBT) may be a useful adjunct in the evaluation of respiratory function in MG.

METHOD

A systematic review of the databases PubMed, EMBASE, and the Cochrane Library was conducted from inception to October 2022 in accordance with PRISMA guidelines and was registered on PROSPERO.

RESULTS

There were 6 studies that fulfilled the inclusion criteria. The described method of evaluating SCBT involves inhaling deeply, then counting at two counts per second, in English or Spanish, sitting upright, with normal vocal register, until another breath needs to be taken. The identified studies support that the SCBT has a moderate correlation with forced vital capacity. These results also support that SCBT can assist the identification of MG exacerbation, including via assessment over the telephone. The included studies support a threshold count of ≥ 25 as consistent with normal respiratory muscle function. Although further analysis is needed, the included studies describe the SCBT as a quick bedside tool that is inexpensive and well tolerated.

CONCLUSIONS

The results of this review support the clinical utility of the SCBT in assessing respiratory function in MG and describe the most current and effective methods of administration.

Real-world utilization patterns of intravenous immunoglobulin in adults with generalized myasthenia gravis in the United States

OBJECTIVE

To evaluate real-world utilization patterns of intravenous immunoglobulin (IVIg) among patients with generalized myasthenia gravis (gMG) over 3 years post-IVIg initiation.

METHODS

Patients with gMG who initiated IVIg treatment were identified from a United States claims database (Symphony Health's Integrated Dataverse [IDV]®, January 1, 2014 - December 31, 2019). The frequency of subsequent IVIg treatment and associated cost during the year post-IVIg initiation were analyzed. Usage patterns of IVIg and concomitant gMG treatments during the year preceding and 3 years post-IVIg initiation were compared.

RESULTS

Among 1225 patients with gMG who initiated IVIg treatment, 706 patients (57.6%) received 1 to 5 IVIg treatment courses (intermittent IVIg users), and 519 patients (42.4%) received ≥6 IVIg treatment courses (chronic IVIg users) within the subsequent year. Mean annual medical cost per patient was nearly 2.5-fold higher for chronic vs. intermittent IVIg users ($161,478 vs. $64,888, p < 0.001). The proportion of patients using corticosteroids and nonsteroidal immunosuppressive treatments (NSISTs) was not reduced over the 3-year follow-up period following IVIg initiation, even for patients who continued annual chronic IVIg for 3 consecutive years post-initiation.

CONCLUSIONS

Nearly half of patients with gMG received chronic and multiple IVIg treatment courses within the first year once initiating IVIg treatment, indicating higher usage than expected. For all IVIg initiators, the proportion of patients using corticosteroids and NSISTs did not decrease over 3 years despite IVIg initiation.

A Case Report and 31-Case Study: Does Takotsubo Cardiomyopathy in Myasthenia Gravis Patients Have a High Mortality Rate?

Myasthenia gravis is an autoimmune disorder in which antibodies are formed against post-synaptic nicotinic acetylcholine receptors that lead to impeded muscle contraction and commonly affects the oculomotor muscles. Takotsubo cardiomyopathy (TTC) is a dilated cardiomyopathy that can mimic a myocardial infarction and causes reversible systolic dysfunction. This is a case of a 66-year-old Caucasian male with a known history of ocular myasthenia gravis that presented to the emergency room with worsening dyspnea secondary to a myasthenic crisis. One day, following admission, his shortness of breath failed to improve and was found to meet the diagnostic criteria for takotsubo cardiomyopathy. A brief review of 31 previous cases summarizes the current case reports, patterns, and mortality associated with the myasthenic crisis associated with TTC.

Peak expiratory flow and the single-breath count test as markers of respiratory function in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratory muscles. Considering the severity of respiratory involvement in MG, routine evaluation of respiratory function is essential. The aim of this study was to identify a useful clinical marker of respiratory involvement in patients with MG.

METHODS

We performed an observational study of patients with MG. All cases were evaluated with the single-breath count test, peak expiratory flow (PEF), a modified Medical Research Council dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP).

RESULTS

The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified as grade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were found between single-breath count test scores and FVC values (r = 0.57, P = .000), and between PEF and FVC values (r = 0.76, P = .000). Severity of dyspnoea according to the mMRC scale showed a negative correlation with FVC values (r = -0.31, P = .03). PEF also showed a significant correlation with MEP (r = 0.51, P = .002).

CONCLUSIONS

PEF, the single-breath count test, and the mMRC scale are useful measures for evaluating respiratory function in patients with MG.

Impact of COVID-19 infection among myasthenia gravis patients- a Cerner Real-World DataTM study

BACKGROUND

Myasthenia gravis (MG) is an auto-immune disease, and the mainstay of therapy is immunomodulation. Such patients are at high risk of acquiring any infections. Hence, we sought to determine the impact of the current global pandemic COVID-19 infection in MG patients.

METHODS

For our study, we used Cerner Real-World Data^TM that was provided through Cerner's HealtheDataLab research tool. We ran a database query from January 2019 to July 2020 in our study and identified myasthenia patients with and without COVID-19 infection. To extract these patients' data, we used ICD 9-CM, ICD-10, and SNOMED-CT codes. We reported the data using means, range, and prevalence rates, and the p-values were calculated using the two-sample t-test and Pearson's chi-squared test.

RESULTS

In the COVID-19 data set, a total of twenty-seven myasthenia patients were identified with a positive COVID-19 infection, and four were diagnosed with an exacerbation. The male to female ratio was equal and one unknown gender (3.7%) with a mean (± SD) age of 64.33 ± 18.42 years. This study group was compared with a non-COVID-19 data set in which a total of sixty-four myasthenia patients were identified, and twenty-three had an exacerbation. Among the 13 hospitalized patients in the two groups, the mean length of hospitalization for the myasthenia patients in the COVID-19 data set was 8.28 days (n = 7), and the non-COVID-19 set was 4.33 days (n = 6), and it was statistically significant (p-value= 0.007).

CONCLUSIONS

The mean length of hospital stay is prolonged in myasthenia patients who tested positive for COVID-19.

Real-World Healthcare Resource Utilization and Cost Burden Assessment for Adults With Generalized Myasthenia Gravis in the United States

Introduction

Limited evidence exists for healthcare resource utilization (HCRU) and costs associated with generalized myasthenia gravis (gMG), a rare autoimmune disorder, for adults in the United States.

Methods

Adults with ≥1 diagnostic claim for MG between 2014 and 2019 were identified using Symphony Health's Integrated Dataverse®. Using a novel algorithm, HCRU and costs over 12 months following index dates were evaluated for patients with gMG including those with exacerbation events. For patients who experienced crisis events, HCRU and costs were analyzed during the 36 months preceding, during, and 12 months following the events.

Results

Mean HCRU and costs were higher for newly diagnosed patients compared with previously diagnosed patients (hospitalizations: 0.46 vs. 0.34; all-cause costs: $26,419.20 vs. $24,941.47; direct costs for gMG treatments: $9,890.37 vs. $9,186.47) and further increased for patients with exacerbation events (hospitalizations: 0.72; all-cause costs: $43,734.15; direct costs for gMG treatments: $21,550.02). For patients who experienced crisis events, HCRU and costs markedly increased during the 12 months immediately before the crisis event (hospitalizations: 1.35; all-cause costs: $49,236.68) compared with the 2 preceding years and increased further during the 12 months following the crisis index date (hospitalizations: 2.78; all-cause costs: $173,956.99). Cost increases were, in large part, attributed to treatments received.

Discussion

New diagnosis, exacerbation, and crisis events were drivers of HCRU and cost for patients with gMG. Particularly, high costs of gMG-specific medications associated with intervention for exacerbation and crisis events contributed to increased all-cause costs.

Utilization of Decision Tree Algorithms for Supporting the Prediction of Intensive Care Unit Admission of Myasthenia Gravis: A Machine Learning-Based Approach

Myasthenia gravis (MG), an acquired autoimmune-related neuromuscular disorder that causes muscle weakness, presents with varying severity, including myasthenic crisis (MC). Although MC can cause significant morbidity and mortality, specialized neuro-intensive care can produce a good long-term prognosis. Considering the outcomes of MG during hospitalization, it is critical to conduct risk assessments to predict the need for intensive care. Evidence and valid tools for the screening of critical patients with MG are lacking. We used three machine learning-based decision tree algorithms, including a classification and regression tree, C4.5, and C5.0, for predicting intensive care unit (ICU) admission of patients with MG. We included 228 MG patients admitted between 2015 and 2018. Among them, 88.2% were anti-acetylcholine receptors antibody positive and 4.7% were anti-muscle-specific kinase antibody positive. Twenty clinical variables were used as predictive variables. The C5.0 decision tree outperformed the other two decision tree and logistic regression models. The decision rules constructed by the best C5.0 model showed that the Myasthenia Gravis Foundation of America clinical classification at admission, thymoma history, azathioprine treatment history, disease duration, sex, and onset age were significant risk factors for the development of decision rules for ICU admission prediction. The developed machine learning-based decision tree can be a supportive tool for alerting clinicians regarding patients with MG who require intensive care, thereby improving the quality of care.

A Complicated Case of Postpartum Myasthenic Crisis

Myasthenia gravis (MG) is the most common autoimmune disorder affecting the neuromuscular junction (NMJ) of voluntary skeletal muscle. This disease is characterized by ptosis, diplopia, facial muscle weakness, bulbar muscle involvement including dysphagia and difficulty chewing, dysarthria, hypophonia, respiratory muscle fatigue, and sometimes generalized weakness. A myasthenic crisis (MC) is a complication of MG. MC is defined as severe worsening of respiratory function necessitating the need for mechanical ventilation. Precipitating factors include infection, certain drugs, pregnancy, childbirth, surgery, discontinuation of medical therapy, or even spontaneously with no inciting event. Here we present a complicated case of a 24-year-old patient with a long history of controlled who encounters many events that lead to an MC necessitating mechanical intubation, plasmapheresis, and high dose immunosuppressive therapy. She recently gave birth to a child, had an occult perforated appendicitis with multiple abscesses needing emergent exploratory laparotomy, and had an overlying COVID-19 infection. The complexity of this disease and its complications warrants careful consideration by physicians in any branch of specialty.

Lessons in clinical reasoning - pitfalls, myths, and pearls: the contribution of faulty data gathering and synthesis to diagnostic error

OBJECTIVES

Errors in clinical reasoning are a major factor for delayed or flawed diagnoses and put patient safety at risk. The diagnostic process is highly dependent on dynamic team factors, local hospital organization structure and culture, and cognitive factors. In everyday decision-making, physicians engage that challenge partly by relying on heuristics - subconscious mental short-cuts that are based on intuition and experience. Without structural corrective mechanisms, clinical judgement under time pressure creates space for harms resulting from systems and cognitive errors. Based on a case-example, we outline different pitfalls and provide strategies aimed at reducing diagnostic errors in health care.

CASE PRESENTATION

A 67-year-old male patient was referred to the neurology department by his primary-care physician with the diagnosis of exacerbation of known myasthenia gravis. He reported shortness of breath and generalized weakness, but no other symptoms. Diagnosis of respiratory distress due to a myasthenic crisis was made and immunosuppressive therapy and pyridostigmine were given and plasmapheresis was performed without clinical improvement. Two weeks into the hospital stay, the patient's dyspnea worsened. A CT scan revealed extensive segmental and subsegmental pulmonary emboli.

CONCLUSIONS

Faulty data gathering and flawed data synthesis are major drivers of diagnostic errors. While there is limited evidence for individual debiasing strategies, improving team factors and structural conditions can have substantial impact on the extent of diagnostic errors. Healthcare organizations should provide the structural supports to address errors and promote a constructive culture of patient safety.

Predictors of outcome in patients with myasthenic crisis undergoing non-invasive mechanical ventilation: A retrospective 20 year longitudinal cohort study from a single Italian center

About 20% of patients with myasthenia gravis (MG) may develop myasthenic crisis (MC) requiring ventilation, either invasive (MV) or non-invasive (NIV) and intensive unit care (ICU). NIV failure in patients with MC can occur up to 60% of cases admitted to ICU. Moreover it is not known the outcome of MC receiving NIV. Purpose of this study was to identify predictors of outcome in MC who underwent non-invasive ventilator support outside ICU setting. We enrolled 90 patients, 53 females and 37 males admitted to University Hospital of Modena (Italy) between January 2000 and September 2020. Median age at MC was 65 years. Thirty-four patients (37.8%) required MV. Thymectomy was performed in 45 cases, associated with thymoma in 55%, with hyperplastic thymus in 33%. First-line treatment was plasmaexchange (38.8%) or intravenous immunoglobulins (45.6%). Males exhibited higher risk of MV than females .Patients in MV were treated with plasmaexchange as first-line therapy . Our in-hospital mortality rate was low. Nine patients underwent tracheostomy which was significantly related to male gender. Comorbidities had significant effect on length of ICU .Our study confirms as predictors of prognosis in our patients male gender, older age at onset, infections as trigger, pneumonia.

Drugs That Induce or Cause Deterioration of Myasthenia Gravis: An Update

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder which is characterized by presence of antibodies against acetylcholine receptors (AChRs) or other proteins of the postsynaptic membrane resulting in damage to postsynaptic membrane, decreased number of AChRs or blocking of the receptors by autoantibodies. A number of drugs such as immune checkpoint inhibitors, penicillamine, tyrosine kinase inhibitors and interferons may induce de novo MG by altering the immune homeostasis mechanisms which prevent emergence of autoimmune diseases such as MG. Other drugs, especially certain antibiotics, antiarrhythmics, anesthetics and neuromuscular blockers, have deleterious effects on neuromuscular transmission, resulting in increased weakness in MG or MG-like symptoms in patients who do not have MG, with the latter usually being under medical circumstances such as kidney failure. This review summarizes the drugs which can cause de novo MG, MG exacerbation or MG-like symptoms in nonmyasthenic patients.

Acetylcholinesterase Inhibitors in Myasthenic Crisis: A Systematic Review of Observational Studies

Current myasthenia gravis guidelines recommend intravenous immunoglobulin or plasmapheresis and discontinuation of pyridostigmine during myasthenic crisis. However, intravenous immunoglobulin or plasmapheresis is expensive and frequently not available in developing countries. This study aims to summarize the evidence of giving an acetylcholinesterase inhibitor in myasthenic crisis. Medline, Embase, and Cochrane databases and references were searched for observational studies that determined the use of acetylcholinesterase inhibitor in myasthenic crisis. The eligibility criteria were as follows: population, patients with myasthenic crisis, intervention (acetylcholinesterase inhibitor administration), and outcome (clinical improvement and complications). In total, 106 studies were identified, 92 through database searching (after removing duplicates) and 14 through other sources. Only eight were analyzed in the present systematic review. In five, acetylcholinesterase inhibitor was given at the start of the crisis, whereas in the other three, acetylcholinesterase inhibitor was discontinued initially and then restarted prior to extubation. Two observational analytic studies and three case reports showed improvement in different outcome measures. In the other three, improvement of outcome measures was also observed. Overall, a small proportion of patients developed cardiac arrhythmia and pneumonia after administration of acetylcholinesterase inhibitor alone, although this was not statistically different compared with those subjected to plasmapheresis. In summary, continuous intravenous infusion of pyridostigmine or neostigmine can be a substitute for intravenous immunoglobulin or plasmapheresis if these are not available during crisis; however, caution should be observed because of the aforementioned possible complications.

Peak expiratory flow and the single-breath counting test as markers of respiratory function in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratory muscles. Considering the severity of respiratory involvement in MG, routine evaluation of respiratory function is essential. The aim of this study was to identify a useful clinical marker of respiratory involvement in patients with MG.

METHODS

We performed an observational study of patients with MG. All cases were evaluated with the single-breath counting test, peak expiratory flow (PEF), a modified Medical Research Council dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP).

RESULTS

The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified as grade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were found between single-breath counting test scores and FVC values (r = 0.57, p = .000), and between PEF and FVC values (r = 0.76, p = .000). Severity of dyspnoea according to the mMRC scale showed a negative correlation with FVC values (r = -0.31, p = .03). PEF also showed a significant correlation with MEP (r = 0.51, p = .002).

CONCLUSIONS

PEF, the single-breath counting test, and the mMRC scale are useful measures for evaluating respiratory function in patients with MG.

Intravenous immunoglobulins may prevent prednisone-exacerbation in myasthenia gravis

Corticosteroids may produce a paradoxical worsening of myasthenia gravis (MG) symptoms within the first weeks of treatment. We therefore wanted to assess the hypothesis that a prior infusion of intravenous immunoglobulin (IVIG) may have a protective effect. Our primary objectives were to show that the coadministration of immunoglobulins and glucocorticoids is safe and effective for controlling myasthenic symptoms, and to compare the exacerbation rate with this approach and historical practice without IVIG. We recruited 45 patients with generalized MG who required corticosteroids for the first time and we gave all IVIG before starting the full doses of prednisone. Monitoring was performed with validated scales, questionnaires, and blood tests over a 6-week period. Only 4.4% had severe adverse effects related to IVIG and 86.7% improved clinically. Notably, only 2.2% had a paradoxical symptom exacerbation in the first weeks of starting prednisone, which was statistically lower than the 42% reported in a historical series. We conclude that adjuvant therapy with IVIG when starting prednisone for the first time in patients with generalized MG is safe and effective. Given that the rate of paradoxical worsening was lower than that previously reported, the addition of IVIG may have a protective effect against such exacerbations.

COVID-19 in Refractory Myasthenia Gravis- A Case Report of Successful Outcome

This is a brief report of a patient who has refractory Myasthenia Gravis, on multiple long-term immunosuppressive therapies and contracted COVID-19 during this 2020 pandemic. She was quarantined for total of 14 days and recovered successfully without any complications (no myasthenia exacerbation or crisis, no COVID-19 related complications), with no changes to her immunosuppressive therapy. Treatment of MG patients with COVID-19 needs to be tailored to individual patient.

Beatmung bei neuromuskulären Erkrankungen

Neuromuskuläre Erkrankungen betreffen das erste und zweite Motoneuron, die peripheren Nerven, die neuromuskulären Übertragung und die Muskelzelle. Es handelt sich um eine heterogene Gruppe von erblichen, degenerativen und autoimmunen Erkrankungen. Eine korrekte diagnostische Einordnung ist erforderlich, da zentralnervöse, kardiale, endokrine und weitere Begleitsymptome vorliegen können und für einige Erkrankungen bereits medikamentöse Therapien zur Verfügung stehen. Neuromuskuläre Erkrankungen haben eine große Bedeutung in der neuromuskulären Beatmungsmedizin. Die respiratorische Symptomatik resultiert in der Regel aus Paresen der am Atmen, Schlucken oder Husten beteiligten Muskulatur mit konsekutiver ventilatorischer Insuffienz, Dysphagie bis hin zur Speichelaspiration und Sekretretention. Mittels eines strukturierte Sekretmanagements und einer effektive nichtinvasive oder invasive Beatmungstherapie können neuromuskuläre Patienten viele Jahre mit guter Lebensqualität überleben. Themen dieses Kapitels sind ein Überblick über die neuromuskulären Erkrankungen, die Indikationen und Strategien der nichtinvasiven und der invasiven Beatmung und eine ausführliche Darstellung beatmungsmedizinisch besonders relevanter neuromuskulärer Erkrankungen wie der amyotrophe Lateralsklerose, des Guillain-Barré-Syndroms, der Myasthenia gravis und der Critical-Illness-Polyneuropathie/-Myopathie.

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.

Myasthenic crisis treated in a Chinese neurological intensive care unit: clinical features, mortality, outcomes, and predictors of survival

BACKGROUND

Myasthenic crisis (MC) often requires admission to an intensive care unit (ICU).

METHODS

We retrospectively investigated 113 consecutive patients with first MC admitted to the neurological ICU. Patients' demographic, clinical and other characteristics were examined, as well as therapeutic interventions, mortality and functional outcome.

RESULTS

MC patients at first onset admitted to neurological ICU had a mortality rate of 18.6%. PCO₂ level before intubation and score on Myasthenia Gravis-Activities of Daily Living (MG-ADL) scale at MC onset correlated with duration of ventilation and length of ICU stay. Compared with patients with good functional outcome, patients with intermediate or poor functional outcome were older at first MC onset, had lower pH and PO₂, and had higher PCO₂ before intubation. Multivariate logistic analysis identified pre-intubation PCO₂ level as an independent predictor of survival. Cox regression showed that age at first MC onset requiring ICU management was the factor which significantly influenced the mortality.

CONCLUSIONS

Our results suggest that PCO₂ before intubation and MG-ADL score at MC onset may be useful indicators of more severe disease likely to require extensive respiratory support and ICU management. Higher pre-intubation PCO₂ indicates chronic respiratory acidosis that can increase risk of severe disability and death, especially in patients with older age at first MC onset.

Intravenous immunoglobulin to prevent myasthenic crisis after thymectomy and other procedures can be omitted in patients with well-controlled myasthenia gravis

Background:

Myasthenic crisis (MC) is a potentially life-threatening complication of myasthenia gravis. Its precipitating factors include surgical procedures, particularly thymectomy. The role of preoperative intravenous immunoglobulin (IVIg) in preventing MC in patients scheduled for thymectomy and other surgery with general anaesthesia is unknown. Our objective was to test the hypothesis that preoperative IVIg is effective in preventing myasthenic crisis in patients with myasthenia gravis scheduled for surgery under general anaesthesia, including thymectomy.

Methods:

A prospective, randomized, double-blind, single-centre study was conducted over a 4-year period. The treatment group received IVIg, 0.4 g/kg/day preoperatively for 5 consecutive days, and the placebo group received saline solution under the same conditions. The two groups were age-matched, with similar functional status, and Myasthenia Gravis Foundation of America class. All patients had well-controlled myasthenia gravis with minimal manifestations before surgery. The primary outcome measured was MC. Intubation times, time in the recovery room, number of postoperative complications, and days of hospitalization were the secondary outcomes measured.

Results:

A total of 47 patients were randomized, 25 to the IVIg group and 22 to placebo. There were 19 men and 28 women, with a mean age of 58.6 years, mean body mass index of 27.8 kg/m², and mean acetylcholine receptor antibodies of 12.9 nmol/l. The mean forced vital capacity was 84.4%. The mean quantitative myasthenia gravis sum score was 6.3. Ten patients (five in each arm) had a history of MC. Thymectomy was performed in 16 patients. Only one patient in the placebo group presented with MC requiring non-invasive ventilation (but no reintubation) for 6 days. Neither differences between groups in the univariate analysis nor risk factors for MC in the multivariate analysis were found.

Conclusions:

Preoperative IVIg to prevent MC does not appear to be justified in well-controlled myasthenia gravis patients. This study provides class I evidence that preparation with IVIg to prevent MC is not necessary in well-controlled myasthenia gravis patients scheduled for surgery with general anaesthesia.

Impact of Refractory Myasthenia Gravis on Health-Related Quality of Life

OBJECTIVES

Myasthenia gravis (MG) may be refractory to traditional therapies. Quality of life (QOL) and disease burden in patients with refractory and nonrefractory MG were compared using Myasthenia Gravis Foundation of America MG Patient Registry data.

METHODS

Adults aged 18 years or older with MG diagnosed ≥2 years before enrollment were included. Participants with refractory MG had received ≥2 previous and 1 current MG treatment and had MG Activities of Daily Living Scale total score ≥6 at enrollment; other participants had nonrefractory MG. MG QOL 15-item scale (MG-QOL15) scores were compared.

RESULTS

In total, 56 participants with refractory and 717 participants with nonrefractory MG enrolled. Participants with refractory MG had significantly higher mean (SD) MG-QOL15 total scores [31.4 (11.1) vs. 20.8 (15.0), P < 0.0001] and were more likely to have had exacerbations, emergency department visits, and recent hospitalizations.

CONCLUSIONS

Participants with refractory MG experience worse QOL and greater clinical burden than those with nonrefractory disease.

Long-term safety and efficacy of eculizumab in generalized myasthenia gravis

Introduction: Eculizumab is effective and well tolerated in patients with antiacetylcholine receptor antibody‐positive refractory generalized myasthenia gravis (gMG; REGAIN; NCT01997229). We report an interim analysis of an open‐label extension of REGAIN, evaluating eculizumab's long‐term safety and efficacy. Methods: Eculizumab (1,200 mg every 2 weeks for 22.7 months [median]) was administered to 117 patients. Results: The safety profile of eculizumab was consistent with REGAIN; no cases of meningococcal infection were reported during the interim analysis period. Myasthenia gravis exacerbation rate was reduced by 75% from the year before REGAIN (P < 0.0001). Improvements with eculizumab in activities of daily living, muscle strength, functional ability, and quality of life in REGAIN were maintained through 3 years; 56% of patients achieved minimal manifestations or pharmacological remission. Patients who had received placebo during REGAIN experienced rapid and sustained improvements during open‐label eculizumab (P < 0.0001). Discussion: These findings provide evidence for the long‐term safety and sustained efficacy of eculizumab for refractory gMG. Muscle Nerve 2019

See editorial on pages 7–9 in this issue.

Repetitive nerve stimulation test in myasthenic crisis

INTRODUCTION

Herein we report our experience with the repetitive nerve stimulation (RNS) test in myasthenia gravis (MG) crisis.

METHODS

The various parameters of the RNS tests in 26 patients with MG crisis were analyzed.

RESULTS

In 18 (69%) patients, MG crisis is the first manifestation of MG. RNS tests were abnormal in 24 (92%) patients by decrement at low-rate stimulation in any of 4 tested muscles. Three patterns of abnormality were found: MG pattern (decrement at low-rate stimulation) in 23 patients; Lambert-Eaton myasthenic syndrome pattern in 1 patient; and cholinergic crisis pattern in 1 patient.

DISCUSSION

During MG crisis, the RNS test can serve as a rapid and sensitive diagnostic tool for MG in a majority of patients. Muscle Nerve 59:544-544, 2019.

Myasthenia gravis crisis coinciding with asthma exacerbation in a patient with recent heroin use: three causes of acute hypercarbic respiratory failure

A 57-year-old woman with a history of asthma, hypertension and substance abuse disorder was admitted to the medical intensive care unit with hypercapnic respiratory failure. After the history was obtained, patient admitted heroin use earlier that day. The initial physical examination revealed right eye ptosis, diplopia, fatigability of neck flexion and extension. She also presented with wheezing and a prolonged expiratory phase. Pupils were 4 mm, with sluggish response to light bilaterally. CT chest with contrast showed a large mediastinal mass. Three different processes coexisted in this patient: simultaneous occurrence of a myasthenia gravis crisis, asthma exacerbation and a component of heroin use. This case highlights a series of overlapping clinical features that could lead to potential confounding and misdiagnosis. Respiratory symptoms improved after initial treatment for asthma exacerbation, but ptosis, diplopia and fatigability of neck muscles persisted.

A diagnosis of late-onset Myasthenia gravis unmasked by topical antibiotics

Myasthenia Gravis (MG) is a disorder of the neuromuscular junction (NMJ) that manifests as fluctuating fatiguable weakness of the muscles. There are many factors that can exacerbate myasthenia symptoms including a variety medications and drugs, systemic illness, and pregnancy. A number of medications have been implicated in exacerbating MG symptoms, including aminoglycosides. We present a case of an elderly female with newly diagnosed MG following the use of tobramycin eye drops for 3 days. There have been limited reports in the literature of topical medications that exacerbate MG symptoms. Clinicians prescribing tobramycin eye drops (or other associated medications) should have a high index of suspicion of MG as early discontinuation and therapy will limit long-term morbidity and mortality in these patients.

Burden of illness in patients with treatment refractory myasthenia gravis

INTRODUCTION

This study assessed the clinical burden of refractory myasthenia gravis (MG), relative to nonrefractory MG.

METHODS

Rates of myasthenic crises, exacerbations, inpatient hospitalizations, and emergency room (ER) visits over a 1-year period were measured for 403 refractory, 3,811 nonrefractory, and 403 non-MG control patients from two administrative health plan databases.

RESULTS

Compared with nonrefractory patients, a significantly greater percentage of refractory patients had at least one myasthenic crisis (21.3% vs. 6.1%; P < 0.001) and at least one exacerbation (71.2% vs. 32.4%; P < 0.001) over a 1-year period. Refractory patients were also significantly more likely to be hospitalized and/or have an ER visit than nonrefractory patients and non-MG controls (P < 0.001 for all).

DISCUSSION

Refractory MG patients have significantly greater clinical burden and are more likely to utilize intensive healthcare resources than nonrefractory patients. Furthermore, refractory patients may be at greater risk of crises throughout the disease course than previous studies have suggested. Muscle Nerve, 2018.

When myasthenia gravis is deemed refractory: clinical signposts and treatment strategies

The prognosis for patients with myasthenia gravis (MG) has improved significantly over the past half century, including substantial reductions in mortality and morbidity. However, approximately 10% of patients fails to respond adequately to current therapies and are considered treatment refractory, or treatment intolerant, and up to 80% have disease that fails to achieve complete stable remission. Although patients with autoantibodies to muscle-specific tyrosine kinase (anti-MuSK positive) are more likely to become treatment refractory than those with autoantibodies to the acetylcholine receptor (anti-AChR positive), each of these serotypes is substantially represented in the refractory MG population. Other risk factors for becoming treatment refractory include history of thymoma or thymectomy and female sex. A modified treatment algorithm for MG is proposed: patients who have disease that fails to respond to the stepwise approach to therapy, are treatment intolerant, or who require chronic rescue measures despite ongoing therapy, should be considered treatment refractory and emerging therapies should be considered. Three emerging monoclonal antibody-based therapies are discussed: the anti-B-cell agent rituximab; the terminal complement activation inhibitor eculizumab; and belimumab, which targets B-cell activating factor. Increased understanding of molecular pathophysiology and accurate antibody subtyping in MG should lead to the use of new therapeutic agents and successful management of treatment-refractory patients.

Myasthenia Gravis and Crisis: Evaluation and Management in the Emergency Department

BACKGROUND

Myasthenia gravis (MG) is an uncommon autoimmune disorder affecting the neuromuscular junction and manifesting as muscle weakness. A multitude of stressors can exacerbate MG. When symptoms are exacerbated, muscle weakness can be severe enough to result in respiratory failure, a condition known as myasthenic crisis (MC).

OBJECTIVE

This review discusses risk factors, diagnosis, management, and iatrogenic avoidance of MC.

DISCUSSION

MC can affect any age, ethnicity, or sex and can be precipitated with any stressor, infection being the most common. MC is a clinical diagnosis defined by respiratory failure caused by exacerbation of MG. Muscle weakness can involve any voluntary muscle. MC can be differentiated from other neuromuscular junction diseases by the presence of normal reflexes, normal sensation, lack of autonomic symptoms, lack of fasciculations, and worsening weakness with repetitive motion. Treatment should target the inciting event and airway support. All acetylcholinesterase inhibitors should be avoided in crisis, including edrophonium testing and corticosteroids initially. Respiratory support can begin with noninvasive positive-pressure ventilation, as this has been successful even in patients with bulbar weakness. If intubation is necessary, consider avoiding paralytics or use a reduced dose of nondepolarizing agents.

CONCLUSIONS

MC should be in the differential of any patient with muscular weakness and respiratory compromise. Emergency department management of MC should focus on ruling out infection and respiratory support. Strong consideration should be given to beginning with noninvasive positive-pressure ventilation for ventilatory support. Corticosteroids, depolarizing paralytics, and acetylcholinesterase inhibitors should be avoided in patients with MC in the emergency department.

Predictive factors of prolonged mechanical ventilation, overall survival, and quality of life in patients with post-thymectomy myasthenic crisis

BACKGROUND

Thymectomy is the primary approach for the treatment of myasthenia gravis (MG). This retrospective study aimed to identify the clinical and demographical features that may impact the duration of mechanical ventilation (DMV), the long-term survival, and the quality of life (QOL) in patients with post-thymectomy myasthenic crisis (PTMC).

METHODS

We reviewed the patients who suffered from PTMC from June 2008 to November 2015. Cox proportional hazard regression analysis was used to identify potential prognostic factors that may impact DMV and long-term survival. Spearman bivariate correlation analysis was used to analyze the relationship between DMV and QOL. Statistical powers were calculated.

RESULTS

In total, 70 patients with PTMC were enrolled. Alcohol abuse, high scores of Myasthenia Gravis Foundation of America (MGFA) classification and Clavien-Dindo classification were critical factors that remarkably delayed early extubation. High scores of Osserman's classification, MGFA classification, and Clavien-Dindo classification predicted a poor prognosis in PTMC patients. Occupational skills and job status were observed to be negatively affected in PTMC patients.

CONCLUSIONS

To decrease the duration of mechanical ventilation, we suggest alcohol abstinence before the operation, appropriate preoperative treatment to decrease MGFA classification, and greater attention to the treatment of postoperative complications.

Management of acute neuromuscular disorders

Imminent neuromuscular respiratory failure is recognized by shortness of breath, restlessness, and tachycardia and is often followed by tachypnea, constantly interrupting speech, asynchronous breathing and sometimes paradoxical breathing and use of scalene and sternocleidomastoid muscles. Once a patient presents with such a constellation of signs, there are some difficult decisions to be made and include assessment of the severity of respiratory failure and in particular when to intubate. Failure of the patient to manage secretions as a result of oropharyngeal weakness rather than neuromuscular respiratory weakness may be another reason for acute intubation. Any patient with rapidly worsening weakness on presentation will need admission and observation in an intensive care unit. This chapter summarizes the pathophysiology of acute neuromuscular respiratory failure, its clinical recognition and respiratory management and outcome expectations.

Management of neuro-oncologic emergencies

Patients with brain tumors and systemic malignancies are subject to diverse neurologic complications that require urgent evaluation and treatment. These neurologic conditions are commonly due to the tumor's direct effects on the nervous system, such as cerebral edema, increased intracranial pressure, seizures, spinal cord compression, and leptomeningeal metastases. In addition, neurologic complications can develop as a result of thrombocytopenia, coagulopathy, hyperviscosity syndromes, infection, immune-related disorders, and adverse effects of treatment. Patients may present with typical disease syndromes. However, it is not uncommon for patients to have more subtle, nonlocalizing manifestations, such as alteration of mental status, that could be attributed to other systemic, nonneurologic complications. Furthermore, neurologic complications are at times the initial manifestations of an undiagnosed malignancy. Therefore a high index of suspicion is essential for rapid assessment and management. Timely intervention may prolong survival and improve quality of life. In this chapter, we will discuss the common neuro-oncologic emergencies, including epidemiology, pathophysiology, clinical presentation, diagnosis, and treatment.

Predictors of extubation outcomes following myasthenic crisis

Objective Myasthenic crisis (MC) is considered the most severe adverse event in patients with myasthenia gravis. The present retrospective study was performed to evaluate the predictors of clinical outcomes in patients with MC. Methods The medical charts of 33 patients (19 women, 14 men) with 76 MC attacks from 2002 to 2014 were retrospectively reviewed. Early extubation (≤7 days) and prolonged ventilation (>15 days) during the MC were used to assess patient outcomes. Results Among the 33 patients, 24 (72.7%) had positive acetylcholine receptor antibody test results and 20 (60.6%) experienced recurrent MC attacks (≥2 episodes) during follow-up (median 83.6 months, range 1.5-177 months). Plasma exchange during an MC was significantly associated with early extubation. Male sex, older age (>50 years), atelectasis, and ventilator-associated pneumonia significantly contributed to prolonged ventilation. In 22 patients who underwent thymectomy, both the duration between MC attacks and the mean number of MC attacks were significantly reduced after surgery. Conclusions Plasma exchange during MC attacks was found to be important for early extubation; older patients and those with atelectasis or ventilator-associated pneumonia were more vulnerable to prolonged ventilation. Thymectomy may be useful to prevent recurrence of MC.

Emergency Department Management of a Myasthenia Gravis Patient with Community-Acquired Pneumonia: Does Initial Antibiotic Choice Lead to Cure or Crisis?

BACKGROUND

Myasthenic crisis is a rare, yet serious condition that carries a 3%-8% mortality rate. Although infection is a common cause of decompensation in myasthenia gravis, several antibiotics classes have also been associated with an exacerbation. Selecting antibiotics can be a daunting clinical task and, if chosen inappropriately, can carry significant deleterious consequences. Not only do clinicians have to focus on treating the underlying infection appropriately, but avoiding antibiotics that may potentiate a myasthenic crisis is also vital.

CASE REPORT

An 85-year-old female with a history of myasthenia gravis presented to the emergency department (ED) with increasing generalized weakness and shortness of breath. Clinical work-up was consistent with a community-acquired pneumonia (CAP) diagnosis. Her medical history included a myasthenia gravis exacerbation shortly after receiving moxifloxacin for CAP. After reviewing the patient's allergies, as well as potential antibiotic triggers, the decision was made to treat with tigecycline. The patient responded well to tigecycline therapy and was deemed stable for discharge on day 4 of hospitalization. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Evaluation of the myasthenia gravis patient frequently originates in the ED. It is important for clinicians to be able to distinguish between an underlying illness and a myasthenic crisis. In the event of an infectious process causing clinical deterioration in a myasthenia patient, optimal antibiotic selection becomes paramount. This patient case highlights the addition of tigecycline to the armamentarium of therapies available to treat myasthenia gravis patients presenting to the emergency department with CAP.

A genome-wide association study of myasthenia gravis

IMPORTANCE

Myasthenia gravis is a chronic, autoimmune, neuromuscular disease characterized by fluctuating weakness of voluntary muscle groups. Although genetic factors are known to play a role in this neuroimmunological condition, the genetic etiology underlying myasthenia gravis is not well understood.

OBJECTIVE

To identify genetic variants that alter susceptibility to myasthenia gravis, we performed a genome-wide association study.

DESIGN, SETTING, AND PARTICIPANTS

DNA was obtained from 1032 white individuals from North America diagnosed as having acetylcholine receptor antibody-positive myasthenia gravis and 1998 race/ethnicity-matched control individuals from January 2010 to January 2011. These samples were genotyped on Illumina OmniExpress single-nucleotide polymorphism arrays. An independent cohort of 423 Italian cases and 467 Italian control individuals were used for replication.

MAIN OUTCOMES AND MEASURES

We calculated P values for association between 8,114,394 genotyped and imputed variants across the genome and risk for developing myasthenia gravis using logistic regression modeling. A threshold P value of 5.0×10(-8) was set for genome-wide significance after Bonferroni correction for multiple testing.

RESULTS

In the overall case-control cohort, we identified association signals at CTLA4 (rs231770; P=3.98×10(-8); odds ratio, 1.37; 95% CI, 1.25-1.49), HLA-DQA1 (rs9271871; P=1.08×10(-8); odds ratio, 2.31; 95% CI, 2.02-2.60), and TNFRSF11A (rs4263037; P=1.60×10(-9); odds ratio, 1.41; 95% CI, 1.29-1.53). These findings replicated for CTLA4 and HLA-DQA1 in an independent cohort of Italian cases and control individuals. Further analysis revealed distinct, but overlapping, disease-associated loci for early- and late-onset forms of myasthenia gravis. In the late-onset cases, we identified 2 association peaks: one was located in TNFRSF11A (rs4263037; P=1.32×10(-12); odds ratio, 1.56; 95% CI, 1.44-1.68) and the other was detected in the major histocompatibility complex on chromosome 6p21 (HLA-DQA1; rs9271871; P=7.02×10(-18); odds ratio, 4.27; 95% CI, 3.92-4.62). Association within the major histocompatibility complex region was also observed in early-onset cases (HLA-DQA1; rs601006; P=2.52×10(-11); odds ratio, 4.0; 95% CI, 3.57-4.43), although the set of single-nucleotide polymorphisms was different from that implicated among late-onset cases.

CONCLUSIONS AND RELEVANCE

Our genetic data provide insights into aberrant cellular mechanisms responsible for this prototypical autoimmune disorder. They also suggest that clinical trials of immunomodulatory drugs related to CTLA4 and that are already Food and Drug Administration approved as therapies for other autoimmune diseases could be considered for patients with refractory disease.