Management of juvenile myasthenia gravis

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

BACKGROUND

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Myasthenia Gravis Masquerading as Status Asthmaticus

Myasthenia gravis, an autoimmune disorder of neuromuscular transmission, can lead to varying degrees of weakness and fatigability of the skeletal musculature. Juvenile myasthenia gravis accounts for 10–15% of all cases of myasthenia gravis. The clinical presentation of juvenile myasthenia gravis varies tremendously, which presents itself as a diagnostic challenge for clinicians. We report a case of a 15-year-old female with mild intermittent asthma presenting with shortness of breath. Acute onset of dyspnea is a common chief complaint amongst the pediatric population with a broad differential diagnosis. Our patient was presumptively treated for status asthmaticus and required invasive mechanical ventilation. After extubating, the patient showed persistent ptosis, which led to the eventual work-up of myasthenia gravis. Upon further review, this patient had months of intermittent symptoms including ptosis and fatigue which went previously undiagnosed. This case demonstrates that dyspnea in an asthmatic can occur from nonairway processes and, if missed, may result in overtreatment of asthma or delayed diagnosis of an important neuromuscular process.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Developing outcome measures of disease activity in pediatric myasthenia

INTRODUCTION

Pediatric myasthenia encompasses juvenile myasthenia gravis (JMG) and congenital myasthenic syndrome (CMS), which are chronic disorders with fluctuating symptoms amenable to medical therapy. Disease activity and treatment response may be difficult to assess, but, unlike adults, outcome measures have not been developed in children.

METHODS

The study was performed in children (0-18 years of age) at the neuromuscular center of a pediatric hospital over a 3-year period. Patients were recruited prospectively as part of their routine clinical care. Demographic data, diagnosis (JMG/CMS), and the following scales were recorded at each visit: Myasthenia Gravis Foundation of America (MGFA) class, Myasthenia Gravis Composite (MGC), and Pediatric Myasthenia-Quality of Life 15 (PM-QOL15).

RESULTS

Thirty-three patients (24 JMG, 9 CMS) were included in the study, 22 had two or more visits. We established known-groups validity of the MGC and PM-QOL15 scores as compared with the MGFA class. To establish concurrent validity, we constructed a receiver-operating characteristic curve and calculated threshold values of MGC and PM-QOL15 with optimal sensitivity and specificity for identifying a patient with more severe (MGFA III or higher) disease. Finally, we demonstrated the concordance between the MGC and PM-QOL15 by their statistically significant positive Pearson and Spearman correlations.

DISCUSSION

Our study suggests that MGC and PM-QOL15 are important disease outcome measures in pediatric myasthenia that are easy to administer and provide reliable assessment of disease activity in the clinic setting. Further studies are needed to validate their use for pediatric clinical research trials.

Immunopathology of Autoimmune Myasthenia Gravis: Implications for Improved Testing Algorithms and Treatment Strategies

Myasthenia gravis (MG) is a heterogeneous condition, characterized by autoantibodies (Abs) that target functionally important structures within neuromuscular junctions (NMJ), thus affecting nerve-to-muscle transmission. MG patients are more often now subgrouped based on the profile of serum autoantibodies, which segregate with clinical presentation, immunopathology, and their response to therapies. The serological testing plays an essential role in confirming MG diagnosis and guiding disease management, although a small percentage of MG patients remain negative for antibodies. With the advancements in new highly effective pathophysiologically-specific immunotherapeutic options, it has become increasingly important to identify the specific Abs responsible for the pathogenicity in individual MG patients. There are several new assays and protocols being developed for the improved detection of Abs in MG patients. This review focuses on the divergent immunopathological mechanisms in MG, and discusses their relevance to improved diagnostic and treatment. We propose a comprehensive "reflex testing," algorithm for the presence of MG autoantibodies, and foresee that in the near future, the convenience and specificity of novel assays will permit the clinicians to consider them into routine systematic testing, thus stimulating laboratories to make these tests available. Moreover, adopting treatment driven testing algorithms will be crucial to identify subgroups of patients potentially benefiting from novel immunotherapies for MG.

Use of therapeutic plasma exchange for pediatric neurological diseases

Therapeutic plasma exchange is used to treat neurological diseases in the pediatric population. Since its first use in pediatric patients with hepatic coma in the form of manual whole blood exchange, therapeutic plasma exchange has been increasingly used to treat these disorders of the nervous system. This expansion is a result of improved techniques and apheresis instruments suitable for small children, as well as the recognition of its applicability to many diseases in the pediatric population. This review provides a historical overview of the use of therapeutic apheresis in children and highlights the most common applications for therapeutic plasma exchange to treat neurological disorders in children.

Response to treatment in pediatric ocular myasthenia gravis

INTRODUCTION

Juvenile myasthenia gravis (JMG), a pediatric autoimmune neuromuscular junction disorder, includes generalized (GMG), and ocular (OMG) variants. We sought to determine whether differences existed between OMG and GMG children regarding demographics or treatment response.

METHODS

We performed retrospective analysis of 60 children with JMG seen between 1990 and 2018. Osserman scores were used to define OMG and GMG. The myasthenia scale of Millichap and Dodge was used to assess treatment responses.

RESULTS

There were no differences between GMG and OMG regarding time interval from disease onset to prednisone initiation (P = .42), or treatment response according to Millichap and Dodge (P = .12). Compared with GMG, OMG children showed younger age of disease onset and better outcomes after treatment. No OMG patients progressed to generalized disease during the follow-up period.

DISCUSSION

Compared with GMG, OMG patients had earlier disease onset and improved outcomes after treatment.

Application of Pyridostigmine in Pediatric Gastrointestinal Motility Disorders: A Case Series

BACKGROUND

Gastrointestinal (GI) motility disorders are common in children. Treatment is challenging with limited medical and surgical options. Pyridostigmine, an acetyl cholinesterase inhibitor, increases acetylcholine at the neuromuscular junction promoting intestinal contractions. Little is known about the role and dosing of pyridostigmine in pediatric GI motility disorders.

METHODS

We present a case series of children with GI dysmotility managed with oral pyridostigmine. Patients' diagnoses include chronic intestinal pseudo-obstruction, gastroparesis with delayed small bowel transit, chronic constipation with failure to thrive, and prolonged ileus after pelvic surgery with chronic opioid use.

RESULTS

Pyridostigmine was effective and safe in all cases. Pyridostigmine decreased abdominal distention, increased bowel movement frequency, and improved enteral feeding tolerance. Effective dosing ranged between 0.25-2.0 mg/kg/day. One patient experienced cramping abdominal pain while on pyridostigmine, but pain resolved after medication was discontinued.

CONCLUSION

We found oral pyridostigmine to be helpful in children with different GI motility problems. Pyridostigmine should be considered in such patients when other treatment interventions have not been beneficial.

Pyridostigmine for the Reversal of Severe Adverse Reactions to Botulinum Toxin in Children

Therapeutic botulinum toxin injections are commonly performed in pediatric otolaryngology. Aerodigestive complications from botulinum toxin injections, although rare, may be serious. Oral pyridostigmine is effective in the symptomatic treatment of these complications. We report 2 cases of aerodigestive complications arising from injection of botulinum toxin that were successfully treated with pyridostigmine.

Clinical Characteristics of Juvenile Myasthenia Gravis in Southern China

Objectives

To describe the clinical profile, clinical outcomes and factors that may affect the outcome of juvenile myasthenia gravis (JMG) patients in southern China.

Methods

We reviewed information relating to JMG patients treated and evaluated at the First Affiliated Hospital, Sun Yat-sen University, between 1998 and 2015. The study involved 327 JMG patients who had been followed up for ≥1 year.

Results

Overall, 77.4% patients showed initial symptoms in the prepubertal period (<12 years). 306 patients showed only ocular symptoms at onset. By the final follow-up, 61 ocular myasthenia gravis (OMG) patients (61/306, 19.9%) had developed generalized myasthenia gravis (GMG). Anti-acetylcholine receptor antibodies (AChR-Ab) titer was an independent risk factor for generalization. Eleven patients (3.4%) experienced spontaneous remission, but four relapsed. Low-dose oral prednisone (0.25 mg/kg) was administered when symptoms did not significantly improve after pyridostigmine treatment. Immunosuppressants were administered when prednisone was unsatisfactory. Optimal outcome was achieved in 59.6% of patients. Specifically, 60 patients (18.3%) attained complete stable remission (CSR), 12 (3.7%) attained pharmaceutical remission (PR), and 123 (37.6%) attained minimal manifestation (MM). In total, 53 OMG patients (21.5%) attained CSR, a significantly higher proportion than among the GMG patients (8.6%, P = 0.009). Moreover, 67.2% of patients with duration <2 years showed significant clinical improvement compared with 46.3% of those with duration >2 years (P < 0.001). Thymectomy did not exhibit definite efficacy for JMG patients.

Conclusion

There was a low frequency of cases positive for AChR-Ab in the Chinese population. AChR-Ab titer was revealed as an independent risk factor for generalization. Low doses of prednisone could treat JMG effectively with few side effects.

Clinical features and evolution of juvenile myasthenia gravis in a French cohort

INTRODUCTION

In this study we determined the clinical, paraclinical, and treatment-related features of juvenile myasthenia gravis (JMG) as well as the clinical course in a cohort of French children.

METHODS

We conducted a retrospective study of 40 patients with JMG at 2 French pediatric neurology departments from April 2004 to April 2014.

RESULTS

Among the patients, 70% had generalized JMG, 52% had positive acetylcholine receptor antibodies, 8% had muscle-specific kinase antibodies, and 40% were seronegative. Treatment with acetylcholinesterase inhibitors was effective and sufficient in 47% of patients. The 6 patients with generalized JMG treated with rituximab and/or immunoadsorption showed improvement. Thirty percent of the patients required hospitalization in an intensive care unit during follow-up (mean 4.7 years). Remission without treatment occurred in 18% of patients.

DISCUSSION

As with adults, JMG has high morbidity, particularly among children with generalized symptoms, and rituximab should be considered early in the course of the disease as a second-line treatment. Muscle Nerve 57: 603-609, 2018.

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.

Pediatric Myasthenia Gravis

Myasthenia gravis is a disorder of neuromuscular transmission that leads to fatigue of skeletal muscles and fluctuating weakness. Myasthenia that affects children can be classified into the following 3 forms: transient neonatal myasthenia, congenital myasthenic syndromes, and juvenile myasthenia gravis (JMG). JMG is an autoimmune disorder that has a tendency to affect the extraocular muscles, but can also affect all skeletal muscles leading to generalized weakness and fatigability. Respiratory muscles may be involved leading to respiratory failure requiring ventilator support. Diagnosis should be suspected clinically, and confirmatory diagnostic testing be performed, including serum acetylcholine receptor antibodies, repetitive nerve stimulation, and electromyography. Treatment for JMG includes acetylcholinesterase inhibitors, immunosuppressive medications, plasma exchange, intravenous immunoglobulins, and thymectomy. Children with myasthenia gravis require monitoring by a pediatric ophthalmologist for the development of amblyopia from ptosis or strabismus.

Juvenile Myasthenia Gravis in Korea: Subgroup Analysis According to Sex and Onset Age

Juvenile myasthenia gravis presents before 18 years of age with different characteristics according to racial background and pubertal development. The authors aimed to determine the clinical characteristics of children and adolescents of Korean ethnicity with myasthenia gravis, and evaluate the presentation and clinical outcomes according to the sex and onset age of the patients. The authors recruited 88 Korean juvenile myasthenia gravis patients between September 2005 and August 2015. Worse clinical severity from presentation, more aggressive treatment strategies, and worse final treatment outcomes were noted in girls with postpubertal onset than in the other patients. The symptoms were milder (pure ocular presentation in 96.6% [85/88]) and the disease course was more benign (94.3% [83/88]) in this study than in the literature. The homogenous racial background might have contributed to these results. These findings highlight the influence of pubertal development and the need for timely and appropriate active treatment, including thymectomy, to improve prognosis.

Multidisciplinary treatment for prepubertal juvenile myasthenia gravis with crisis

The management of juvenile myasthenia gravis (MG) remains controversial. We report herein the case of a 12-year-old girl with prepubertal juvenile MG with respiratory crisis who underwent thymectomy following methylprednisolone pulse therapy. The patient initially developed progressively worsening fatigability, eyelid ptosis, and diplopia, followed by worsening generalized weakness, dysphagia, and dyspnea. Even after i.v. immunoglobulin, the patient presented with rapid onset of severe dyspnea requiring respiratory support with mechanical ventilation and was graded as Myasthenia Gravis Foundation of America class V. After a course of i.v. methylprednisolone pulse therapy, successful control of respiratory crisis was achieved, and trans-sternal thymectomy was performed. Partial remission was achieved postoperatively with oral pyridostigmine without immunosuppressive agents such as steroids or calcineurin inhibitors for 18 months after thymectomy. Early thymectomy following induction methylprednisolone pulse therapy might be a treatment option for prepubertal juvenile MG with severe respiratory crisis.

Clinical Features and Diagnostic Usefulness of Antibodies to Clustered Acetylcholine Receptors in the Diagnosis of Seronegative Myasthenia Gravis

IMPORTANCE

Cell-based assays (CBAs) were shown to improve detection of acetylcholine receptor (AChR) antibodies in patients with myasthenia gravis (MG). Herein, we asked whether these assays were able to help determine the diagnosis in patients studied in routine clinical practice.

OBJECTIVES

To determine the diagnostic usefulness of CBAs in the diagnosis of MG and to compare the clinical features of patients with antibodies only to clustered AChRs with those of patients with seronegative MG (SNMG).

DESIGN, SETTING, AND PARTICIPANTS

All patients with clinical suspicion of MG who were seen within the Division of Clinical Neurology at the John Radcliffe Hospital in Oxford, England, between November 1, 2009, and November 30, 2013. Their serum antibodies and clinical features were studied.

EXPOSURES

Radioimmunoprecipitation assay (RIPA) and CBA were used to test for standard AChR antibodies and antibodies to clustered AChRs in 138 patients. All available samples from patients with SNMG were retrospectively tested for lipoprotein receptor-related protein 4 (LRP4) antibodies.

MAIN OUTCOMES AND MEASURES

Demographic, clinical, neurophysiological, and laboratory data.

RESULTS

In total, 138 patients were tested for antibodies to clustered AChRs, and 42 had a final diagnosis of MG. The clustered AChR CBA detected antibodies in 38.1% (16 of 42) of RIPA-negative patients with MG with 100% specificity. All patients with SNMG who were tested for LRP4 antibodies (21 of 26) were negative by CBA. Compared with patients with SNMG, patients with antibodies only to clustered AChRs had frequent prepubertal onset (62.5% [median age, 6 years; age range, 1-52 years] vs 11.5% [median age, 38 years; age range, 2-72 years], P ≤ .05), high prevalence of ocular MG (62.5% vs 42.3%), milder disease severity with less bulbar involvement (25.0% vs 46.2%), and absence of respiratory symptoms (0% vs 23.1%). Response to treatment and prognosis was good, with a reduced need for thymectomy (6.3% vs 19.2%) and a high proportion of patients going into remission (50.0% vs 8.3%, P ≤ .05). These observations also apply to the classic AChR MG phenotype seen in large series.

CONCLUSIONS AND RELEVANCE

Cell-based assay is a useful procedure in the routine diagnosis of RIPA-negative MG, particularly in children. Patients with antibodies only to clustered AChRs appear to be younger and have milder disease than other patients with MG. These observations will have implications in planning treatment.

Analysis of serum miRNA profiles of myasthenia gravis patients

Myasthenia gravis (MG) is an autoimmune disease characterized by the presence of autoantibodies, mainly against the acetylcholine receptor (AChR). The mechanisms triggering and maintaining this chronic disease are unknown. MiRNAs are regulatory molecules that play a key role in the immune system and are altered in many autoimmune diseases. The aim of this study was to evaluate miRNA profiles in serum of 61 AChR MG patients. We studied serum from patients with early onset MG (n = 22), late onset MG (n = 27) and thymoma (n = 12), to identify alterations in the specific subgroups. In a discovery cohort, we analysed 381 miRNA arrays from 5 patients from each subgroup, and 5 healthy controls. The 15 patients had not received any treatment. We found 32 miRNAs in different levels in MG and analysed 8 of these in a validation cohort that included 46 of the MG patients. MiR15b, miR122, miR-140-3p, miR185, miR192, miR20b and miR-885-5p were in lower levels in MG patients than in controls. Our study suggests that different clinical phenotypes in MG share common altered mechanisms in circulating miRNAs, with no additional contribution of the thymoma. MG treatment intervention does not modify the profile of these miRNAs. Novel insights into the pathogenesis of MG can be reached by the analysis of circulating miRNAs since some of these miRNAs have also been found low in MG peripheral mononuclear cells, and have targets with important roles in B cell survival and antibody production.