Myasthenia Gravis and Physical Exercise: A Novel Paradigm

Current state of research on exercise for the treatment of myasthenia gravis: A scoping review

OBJECTIVE

To provide a comprehensive overview of existing evidence, research gaps, and future research priorities concerning the treatment of myasthenia gravis (MG) using exercise therapies.

METHOD

Clinical studies on exercise treatment for MG were searched in nine databases to conduct a scoping review. Two independent researchers screened the literature and comprehensively analyzed the characteristics and limitations of the included articles.

RESULTS

A total of 5725 studies were retrieved, of which 24 were included. The included studies were conducted in 16 different countries/regions and 456 patients were enrolled. Study designs included both interventional and observational studies. Exercise interventions included aerobic exercise, resistance exercise, balance training, and stretch training, and are typically administered in conjunction with medication, usual care, or some other interventions. The intensity, frequency, and duration of exercise interventions varied hugely among studies. Six-minute walk test, adverse events, muscle strength, MG quality of life-15 scale, forced vital capacity, quantitative MG scale, and MG activities of daily living scale were the most frequently used outcomes. All studies reported results in favor of the efficacy and safety of exercise in MG, and exercise-related adverse events were reported in two studies.

CONCLUSION

This scoping review provides an overview of the evidence concerning exercise treatment for MG. Key gaps in evidence include a limited number of participants, complex interventions, variability in outcome selection, and insufficient reporting in publications. The promotion of exercise treatment for MG still encounters several obstacles. A larger population, rigorous study design and conduction, standardized interventions and outcomes, and standardized reporting are essential.

Antibody Response to HERV-K and HERV-W Envelope Epitopes in Patients with Myasthenia Gravis

Myasthenia gravis is an antibody-mediated autoimmune neurological disorder characterized by impaired neuromuscular junction transmission, resulting in muscle weakness. Recently, the involvement of Human Endogenous Retroviruses (HERVs) in the pathophysiology of different immune-mediated and neurodegenerative diseases, such as multiple sclerosis, has been demonstrated. We aimed to investigate potential immune system involvement related to humoral responses targeting specific epitopes of HERV-K and HERV-W envelope proteins in myasthenia gravis. Myasthenia gravis patients were recruited in the Neurology Unit, while healthy controls were selected from the Blood Transfusion Center, both affiliated with AOU Sassari. Highly immunogenic antigens of HERV-K and HERV-W envelope proteins were identified using the Immune Epitope Database (IEDB) online tool. These epitopes were utilized in enzyme-linked immunosorbent assays (ELISA) to detect autoantibodies in serum directed against these sequences. The study involved 39 Healthy Donors and 47 MG patients, further categorized into subgroups based on the presence of autoantibodies: MG-AchR Ab+ (n = 17), MG-MuSK Ab+ (n = 7), double seronegative patients (MG-DSN, n = 18), MG-LRP4 Ab + (n = 4), and one patient with no antibodies data (n = 1). Our findings revealed high levels of autoantibodies in myasthenia gravis patients directed against the HERV-K-env-su(19-37), HERV-K-env-su(109-126), HERV-K-env-su(164-186), HERV-W-env(93-108), HERV-W-env(129-14), and HERV-W-env(248-262) epitopes. Notably, these results remained highly significant even when patients were subdivided into MG-AchR Ab+ and MG-DSN subgroups. Correlation analysis further revealed significant positive associations between the antibody levels against HERV-K and HERV-W families in patients, suggesting a synergistic action of the two HERVs in the pathology context since this correlation is absent in the control group. This study marks the first identification of a specific humoral response directed against defined epitopes of HERV-K and HERV-W envelope proteins in myasthenia gravis patients. These findings lay the foundation for future investigations aimed at elucidating the molecular mechanisms driving this immune response. The detection of these autoantibodies suggests the potential for novel biomarkers, especially within the MG-DSN patient subgroup, addressing the need for new biomarkers in this population.

Myasthenia Gravis: Novel Findings and Perspectives on Traditional to Regenerative Therapeutic Interventions

The prevalence of myasthenia gravis (MG), an autoimmune disorder, is increasing among all subsets of the population leading to an elevated economic and social burden. The pathogenesis of MG is characterized by the synthesis of autoantibodies against the acetylcholine receptor (AChR), low-density lipoprotein receptor-related protein 4 (LRP4), or muscle-specific kinase at the neuromuscular junction, thereby leading to muscular weakness and fatigue. Based on clinical and laboratory examinations, the research is focused on distinguishing MG from other autoimmune, genetic diseases of neuromuscular transmission. Technological advancements in machine learning, a subset of artificial intelligence (AI) have been assistive in accurate diagnosis and management. Besides, addressing the clinical needs of MG patients is critical to improving quality of life (QoL) and satisfaction. Lifestyle changes including physical exercise and traditional Chinese medicine/herbs have also been shown to exert an ameliorative impact on MG progression. To achieve enhanced therapeutic efficacy, cholinesterase inhibitors, immunosuppressive drugs, and steroids in addition to plasma exchange therapy are widely recommended. Under surgical intervention, thymectomy is the only feasible alternative to removing thymoma to overcome thymoma-associated MG. Although these conventional and current therapeutic approaches are effective, the associated adverse events and surgical complexity limit their wide application. Moreover, Restivo et al. also, to increase survival and QoL, further recent developments revealed that antibody, gene, and regenerative therapies (such as stem cells and exosomes) are currently being investigated as a safer and more efficacious alternative. Considering these above-mentioned points, we have comprehensively reviewed the recent advances in pathological etiologies of MG including COVID-19, and its therapeutic management.

Myasthenic crisis

Myasthenic crisis (MC) is a life-threatening manifestation of myasthenia gravis (MG) defined by respiratory insufficiency that requires the use of invasive or non-invasive ventilation. This is often the result of respiratory muscle weakness but can also be due to bulbar weakness with upper airway collapse. MC occurs in approximately 15%-20% of patients with MG usually within the first 2 to 3 y of the disease course. Many crises have a specific trigger with respiratory infections being most common; however, no specific trigger is found in 30%-40% of patients. MG patients with a history of MC, severe disease, oropharyngeal weakness, muscle-specific kinase (MuSK) antibodies and thymoma appear to be at higher risk. Most episodes of MC do not occur suddenly, providing a window of opportunity for prevention. Immediate treatment is directed toward airway management and removing any identified triggers. Plasmapheresis is preferred over intravenous immune globulin as the treatments of choice for MC. The majority of patients are able to be weaned from mechanical ventilation within 1 mo and the outcomes of MC are generally favorable. The mortality rate in United States cohorts is less than 5% and mortality in MC seems to be driven by age and other medical co-morbidities. MC does not appear to affect long-term prognosis as many patients are able to eventually achieve good MG control.

Diagnosis and Management of Myasthenia Gravis

PURPOSE OF REVIEW

This article reviews updated diagnostic procedures and currently available treatment modalities for myasthenia gravis (MG).

RECENT FINDINGS

Patients with MG can be classified based on antibody status and their clinical presentation; treatment responses may differ based on disease subtypes. Improved diagnostic methods and recognition of new antigenic targets such as lipoprotein-related protein 4 have led to improved diagnostic efficiencies. Corticosteroids remain the first-line immunotherapy, but there is a trend toward minimizing their use at high doses and for long durations. Oral immunosuppressants such as mycophenolate mofetil, azathioprine, and tacrolimus remain useful. An international, multicenter randomized trial comparing thymectomy plus prednisone with prednisone alone demonstrated that thymectomy improves clinical outcomes in selected patients with nonthymomatous MG. Eculizumab, efgartigimod, and ravulizumab have recently been approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive. These drugs take advantage of novel mechanisms of action and expand treatment options for patients with MG. Data on rituximab suggest that it can be a good option, especially for patients with MG who are positive for antibodies against muscle-specific tyrosine kinase (MuSK). The number of clinical trials and drugs in development for MG is steadily increasing.

SUMMARY

The diagnosis of MG can generally be made from the patient's history, a neurologic examination, and laboratory and electrodiagnostic testing. Carefully selected treatment improves outcomes in MG. Additional treatment options for MG will likely be available in the near future.

The validity of the International Physical Activity Questionnaire (IPAQ) for adults with progressive muscle diseases

PURPOSE

Measuring the physical activity of adults with progressive muscle diseases is important to inform clinical practice, for activity recommendations and for outcomes meaningful to participants in clinical trials. Despite its wide use, the measurement properties of the International Physical Activity Questionnaire (IPAQ) have not been established in a muscle disease population.

MATERIALS AND METHODS

The sample of 103 adults with progressive muscle diseases included independently mobile participants and wheelchair users. Their home-based activity measured by the IPAQ was compared to simultaneous weeks of accelerometer activity data collected remotely in a longitudinal, measure evaluation study. Validity, reliability, and responsiveness were evaluated for the IPAQ alone, and for the IPAQ used in conjunction with a smart activity monitor.

RESULTS

The IPAQ did not demonstrate satisfactory criterion validity, reliability or responsiveness and it systematically overestimated moderate and vigorous physical activity time by 161 minutes per week. Measurement properties of the IPAQ were improved when it was used in combination with a smart activity monitor.

CONCLUSIONS

The IPAQ did not have satisfactory measurement properties compared to accelerometry in adults with progressive muscle disease. Combining self-report and objective activity measures might improve the accuracy of physical activity assessment in this and other comparable populations.Implications for RehabilitationPhysical activity is a meaningful health outcome for adults with progressive muscle diseases, for whom precise activity quantification is important because of the potential for activity-related disease exacerbation.The International Physical Activity Questionnaire (IPAQ) had unsatisfactory measurement properties compared to accelerometry; however, these were improved by adjunctive smart activity monitoring.Objective or combined physical activity measurement is recommended over self-report alone for clinical assessment of physical activity as part of rehabilitation and self-management programmes.

Prevention of Adverse Outcomes and Treatment Side Effects in Patients with Neuromuscular Disorders

In this article, we review prevention of serious adverse clinical outcomes and treatment side effects in patients with neuromuscular disorders including myopathies and myasthenia gravis. While neither of these entities is preventable, their course can often be modified, and severe sequelae may be prevented, with the identification of risk factors and proactive attention toward treatment planning.

Patient-Reported Symptom Burden of Charcot-Marie-Tooth Disease Type 1A: Findings From an Observational Digital Lifestyle Study

OBJECTIVES

This study aims to explore the impact of Charcot-Marie-Tooth disease type 1A (CMT1A) and its treatment on patients in European (France, Germany, Italy, Spain, and the United Kingdom) and US real-world practice.

METHODS

Adults with CMT1A (n = 937) were recruited to an ongoing observational study exploring the impact of CMT. Data were collected via CMT&Me, an app through which participants completed patient-reported outcome measures.

RESULTS

Symptoms ranked with highest importance were weakness in the extremities, difficulty in walking, and fatigue. Almost half of participants experienced a worsening of symptom severity since diagnosis. Anxiety and depression were each reported by over one-third of participants. Use of rehabilitative interventions, medications, and orthotics/walking aids was high.

CONCLUSIONS

Patient-reported burden of CMT1A is high, influenced by difficulties in using limbs, fatigue, pain, and impaired quality of life. Burden severity appears to differ across the population, possibly driven by differences in rehabilitative and prescription-based interventions, and country-specific health care variability.

Experience of physical activity in patients with COPD: A systematic review and qualitative meta-synthesis

OBJECTIVE

To systematically evaluate and integrate the qualitative research on physical activity (PA) experience of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Web of Science, Cochrane Library, Embase, CINAHL and other databases were searched, and the qualitative research on PA experience of patients with COPD was collected. The systematic review was conducted in line with Joanna Briggs Institute (JBI) methodology for systematic reviews of qualitative evidence.

RESULTS

12 studies were included and 3 themes were summarized, included: COPD patients experience more barriers while participating in physical activities than facilitators; COPD patients experience more positive effects post-physical activities than negative effects; Guaranteeing safety, goal setting, and establishing a professional support group improve compliance in COPD patients.

CONCLUSION

Health care professionals should help patients overcome the obstacles of PA, pay attention to the PA experience of patients, adopt diversified PA methods, improve PA participation and compliance, and make patients develop good PA habits.

Serum irisin levels in patients with myasthenia gravis

OBJECTIVE

Myasthenia gravis (MG) is an autoimmune disorder whose main symptoms are muscle weakness and fatigue. Irisin is a novel skeletal muscle-derived myokine participating in several physiological and pathological processes. The initial objective of the project was to explore serum levels of irisin in patients with MG, as well as its correlation with disease severity.

METHODS

We retrospectively evaluated serum levels of irisin in 77 MG patients and 57 healthy controls (HCs) by enzyme-linked immunosorbent assay. Further, clinical parameters were measured properly.

RESULTS

Serum irisin levels were significantly elevated in MG patients compared with HCs (p < 0.001). Furthermore, serum irisin levels were associated with the myasthenia gravis activities of daily living score in ocular myasthenia gravis (OMG) patients (r = 0.476, p = 0.004), but there was no relationship to be considered of any relevant value in generalized myasthenia gravis (GMG) patients. Acetylcholine receptor antibody-positive MG patients had higher serum irisin levels compared with HCs. Thymoma, endotracheal intubation, or intensive care unit treatments subsequently were not found to have effect on serum levels of irisin, but tendencies of increase were observed in negative ones.

CONCLUSIONS

Serum irisin levels were elevated in patients with MG, suggesting its possible involvement in MG. And irisin is expected to be a signal to evaluate the activities of daily living of OMG patients, while its effect needs further study.

Changes in Physical Fitness and Body Composition Associated with Physical Exercise in Patients with Myasthenia Gravis: A Longitudinal Prospective Study

There is a lack of guidelines for physical exercise in patients with myasthenia gravis (MG). A few pilot studies have shown that exercise can be safely applied to patients with MG. However, how physical exercise affects body composition, disease function, and disease severity remains unknown. In this prospective study, we enrolled 34 patients with MG with stable condition and evaluated the disease severity, physical fitness parameters, and body composition (measured using whole-body dual-energy X-ray absorptiometry (DXA)), before and after conducting a 24-week physical exercise regimen of aerobic and resistance strength training. The outcomes were measured by DXA, quantitative MG (QMG) score, quality of life score, handgrip strength and walking speed. During the training regimen, participants were free to decide how many exercise sessions per week and regularly reported their weekly exercise time. The physical exercise program was well tolerated by the participants, the parameters of the QMG score and handgrip strength improved, and participants’ body composition did not change significantly. The high exercise group experienced greater deterioration in muscle mass in the arms, but exhibited a greater improvement in forced vital capacity, walking speed, and symptom severity. The group with low QMG scores improved more in terms of physical fitness, including walking speed. These findings indicate that physical exercise is well tolerated by patients with MG, and is accompanied by improved muscular and physical functions. We propose that physical exercise is safe, effective, and appropriate for patients with well-regulated MG.

The Neuromuscular Junction: Roles in Aging and Neuromuscular Disease

The neuromuscular junction (NMJ) is a specialized synapse that bridges the motor neuron and the skeletal muscle fiber and is crucial for conversion of electrical impulses originating in the motor neuron to action potentials in the muscle fiber. The consideration of contributing factors to skeletal muscle injury, muscular dystrophy and sarcopenia cannot be restricted only to processes intrinsic to the muscle, as data show that these conditions incur denervation-like findings, such as fragmented NMJ morphology and corresponding functional changes in neuromuscular transmission. Primary defects in the NMJ also influence functional loss in motor neuron disease, congenital myasthenic syndromes and myasthenia gravis, resulting in skeletal muscle weakness and heightened fatigue. Such findings underscore the role that the NMJ plays in neuromuscular performance. Regardless of cause or effect, functional denervation is now an accepted consequence of sarcopenia and muscle disease. In this short review, we provide an overview of the pathologic etiology, symptoms, and therapeutic strategies related to the NMJ. In particular, we examine the role of the NMJ as a disease modifier and a potential therapeutic target in neuromuscular injury and disease.

Therapeutic plasma exchange in neuroimmune diseases. Rehabilitation in myasthenia gravis patients treated with apheresis procedures

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique which removes large molecular weight particles, like autoantibodies, from plasma. Double filtration plasmapheresis (DFPP) is a newer technique in which plasma is not entirely removed, only the antibodies, using special filters. Myasthenia gravis (MG) is a well-known autoimmune disease characterized by antibodies against postsynaptic nicotinic acetylcholine receptors and fluctuating weakness, sometimes life-threatening. TPE is a therapeutic modality well established in MG with a positive recommendation based on strong consensus of class III evidence and in the category I of American society for apheresis. There are no adequate randomized control trial, but many cases report short-term benefit from plasma exchange in MG especially MGC. We analyzed the cases of neuroimmune disorders that were presented to our Emergency Care Unit between 2012-2020 and we concluded that good acceptance of procedure (TPE/DFPP) was observed in 72% of patients. TPE is cost-effective rapid therapy for myasthenic crisis and progressive myasthenia gravis. It reduces ICU stays and improves outcome.All in all recent studies show that the combination of rehabilitation and other forms of treatment, appropriately selected activities contribute to alleviating the symptoms of the disease, improving physical fitness, increasing muscle strength, and thus improving the quality of life. Keywords: therapeutic plasma exchange, plasmapheresis, neuroimmune disorders,rehabilitation,