Quantitative myasthenia gravis score: assessment of responsiveness and longitudinal validity

The placebo response in myasthenia gravis assessed by quantitative myasthenia gravis score: A meta-analysis

INTRODUCTION

This meta-analysis investigates the placebo response in generalized myasthenia gravis (MG) trials by means of Quantitative Myasthenia Gravis (QMG) scores.

METHODS

PubMed, Scopus, Web of Science, Cochrane Controlled Trial Register, and EMBASE were searched. QMG score, dropouts rate, adverse events (AEs), and AEs responsible for dropouts were examined, together with treatment moderators.

RESULTS

The magnitude of placebo response showed an effect size of 0.24, which was significantly lower than 0.67 of the drug response (P = 0.019). Furthermore, the forest plot revealed that, overall, active treatments showed a significantly higher impact on QMG scores than placebos.

CONCLUSIONS

Placebo and drug responses in MG trials are small and moderate, respectively. The lack of MG trials with a pure placebo arm or a no-treatment control arm made it impossible to disentangle improvements due to the placebo psychological effect from other effects such as natural history and/or regression to the mean. Muscle Nerve 59:671-678, 2019.

A Neurologist's Perspective on Thymectomy for Myasthenia Gravis: Current Perspective and Future Trials

The first randomized blinded study of thymectomy in nonthymomatous myasthenia gravis was designed to answer 3 questions: does the combination of prednisone and removal of the thymus gland via extended transsternal thymectomy after 3 years compared with an identical dosing protocol of prednisone alone (1) lead to better disease status for generalized MG patients with antiacetylcholine receptor antibodies, (2) reduce their prednisone requirements, and/or (3) reduce the side-effect burden from medications used to treat the disease? The study demonstrated that thymectomy confers these benefits for patients and sets the stage for inquiries into the benefits of less-invasive approaches to thymic resection.

Long-term effect of thymectomy plus prednisone versus prednisone alone in patients with non-thymomatous myasthenia gravis: 2-year extension of the MGTX randomised trial

BACKGROUND

The Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone (MGTX) showed that thymectomy combined with prednisone was superior to prednisone alone in improving clinical status as measured by the Quantitative Myasthenia Gravis (QMG) score in patients with generalised non-thymomatous myasthenia gravis at 3 years. We investigated the long-term effects of thymectomy up to 5 years on clinical status, medication requirements, and adverse events.

METHODS

We did a rater-blinded 2-year extension study at 36 centres in 15 countries for all patients who completed the randomised controlled MGTX and were willing to participate. MGTX patients were aged 18 to 65 years at enrolment, had generalised non-thymomatous myasthenia gravis of less than 5 years' duration, had acetylcholine receptor antibody titres of 1·00 nmol/L or higher (or concentrations of 0·50-0·99 nmol/L if diagnosis was confirmed by positive edrophonium or abnormal repetitive nerve stimulation, or abnormal single fibre electromyography), had Myasthenia Gravis Foundation of America Clinical Classification Class II-IV disease, and were on optimal anticholinesterase therapy with or without oral corticosteroids. In MGTX, patients were randomly assigned (1:1) to either thymectomy plus prednisone or prednisone alone. All patients in both groups received oral prednisone at doses titrated up to 100 mg on alternate days until they achieved minimal manifestation status. The primary endpoints of the extension phase were the time-weighted means of the QMG score and alternate-day prednisone dose from month 0 to month 60. Analyses were by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00294658. It is closed to new participants, with follow-up completed.

FINDINGS

Of the 111 patients who completed the 3-year MGTX, 68 (61%) entered the extension study between Sept 1, 2009, and Aug 26, 2015 (33 in the prednisone alone group and 35 in the prednisone plus thymectomy group). 50 (74%) patients completed the 60-month assessment, 24 in the prednisone alone group and 26 in the prednisone plus thymectomy group. At 5 years, patients in the thymectomy plus prednisone group had significantly lower time-weighted mean QMG scores (5·47 [SD 3·87] vs 9·34 [5·08]; p=0·0007) and mean alternate-day prednisone doses (24 mg [SD 21] vs 48 mg [29]; p=0·0002) than did those in the prednisone alone group. 14 (42%) of 33 patients in the prednisone group, and 12 (34%) of 35 in the thymectomy plus prednisone group, had at least one adverse event by month 60. No treatment-related deaths were reported during the extension phase.

INTERPRETATION

At 5 years, thymectomy plus prednisone continues to confer benefits in patients with generalised non-thymomatous myasthenia gravis compared with prednisone alone. Although caution is appropriate when generalising our findings because of the small sample size of our study, they nevertheless provide further support for the benefits of thymectomy in patients with generalised non-thymomatous myasthenia gravis.

FUNDING

National Institutes of Health, National Institute of Neurological Disorders and Stroke.

A prospective, double-blind, randomized, placebo-controlled study on the efficacy and safety of influenza vaccination in myasthenia gravis

OBJECTIVE

To investigate the efficacy and safety of an influenza vaccination in patients with myasthenia gravis with acetylcholine receptor antibodies (AChR MG).

METHODS

An influenza vaccination or placebo was administered to 47 AChR MG patients. Before and 4 weeks after administration blood samples and clinical outcome scores were obtained. Antibodies to the vaccine strains A/California/7/2009 (H1N1)pdm09, A/Hong Kong/4801/14 (H3N2) and B/Brisbane/060/08 were measured using the hemagglutination-inhibition (HI) assay and disease-specific AChR antibody titers were measured with a radio-immunoprecipitation assay. Forty-seven healthy controls (HC) were vaccinated with the same influenza vaccine to compare antibody titers.

RESULTS

A post-vaccination, seroprotective titer (HI ≥ 1:40) was achieved in 89.4% of MG patients vs. 93.6% in healthy controls for the H3N2 strain, 95.7% vs 97.9% for the H1N1 strain and 46.8 vs 51% for the B-strain. A seroprotective titer for all three strains of the seasonal influenza vaccine was reached in 40.4% (19/47) of the MG group and in 51% (24/47) of the HC group. Immunosuppressive medication did not significantly influence post geomean titers (GMT). The titers of disease-specific AChR antibodies were unchanged 4 weeks after vaccination. The clinical outcome scores showed no exacerbation of MG symptoms.

CONCLUSION

The antibody response to an influenza vaccination in patients with AChR MG was not different from that in healthy subjects, even in AChR MG patients using immunosuppressive medication. Influenza vaccination does not induce an immunological or clinical exacerbation of AChR MG.

CLINICAL TRIAL REGISTRY

The influenza trial is listed on clinicaltrialsregister.eu under 2016-003138-26.

Amifampridine phosphate in the treatment of muscle-specific kinase myasthenia gravis: a phase IIb, randomized, double-blind, placebo-controlled, double crossover study

Objective:

The aim of this study is to determine the safety and the efficacy of amifampridine phosphate in muscle-specific kinase antibody-positive myasthenia gravis, in a 1:1 randomized, double-blind, placebo-controlled, switchback, double crossover study.

Methods:

Eligible patients had muscle-specific kinase myasthenia gravis, >18 years of age, and Myasthenia Gravis Foundation of America class II–IV with a score of ⩾9 on Myasthenia Gravis Composite scale. After the run-in phase, during which amifampridine phosphate was titrated to a tolerable and effective dosage, patients were randomized to receive placebo–amifampridine–placebo sequence or amifampridine–placebo–amifampridine sequence daily for 7 days. Then, patients switched treatment arms twice, for a total of 21 days of double-blind treatment. Safety was determined by serial assessments of adverse events/serious adverse events, physical examinations, and clinical and laboratory tests. The co-primary outcome measures included changes from baseline of Quantitative Myasthenia Gravis score and Myasthenia Gravis–specific Activities of Daily Living Profile score. The secondary outcome measures comprised changes from baseline of Myasthenia Gravis Composite score, Myasthenia Gravis Quality of Life scale—15 questions, Fatigue Severity Scale, and Carlo Besta Neurological Institute–Myasthenia Gravis scale. Statistical analyses were assessed using a switchback model for three-period, two-treatment crossover design.

Results:

A total of 10 patients were screened, enrolled, and treated. Transient paresthesias (60%) were the only amifampridine phosphate–related adverse events reported. Four patients were randomized to receive placebo–amifampridine–placebo sequence and three patients to receive amifampridine–placebo–amifampridine sequence. The co-primary objectives were statistically met (Quantitative Myasthenia Gravis score: p = 0.0003 and Myasthenia Gravis–specific Activities of Daily Living Profile score: p = 0.0006), as well as all the secondary endpoints (Myasthenia Gravis Composite score: p < 0.0001, Myasthenia Gravis Quality of Life scale—15 questions: p = 0.0025, Fatigue Severity Scale: p = 0.0061, and Carlo Besta Neurological Institute–Myasthenia Gravis scale: p = 0.0014).

Conclusion:

Despite the low number of patients, MuSK-001 study provided evidence that amifampridine phosphate, in the range of 30–60 mg daily dose, was safe and effective in treating muscle-specific kinase myasthenia gravis, suggesting the need for a large multi-center trial to confirm these results.

The impact of physical exercise on neuromuscular function in Myasthenia gravis patients: A single-subject design study

There is a need for tailored exercise recommendations to patients with Myasthenia gravis (MG). A few pilot studies have recently shown that physical exercise in accordance with general recommendations to healthy adults can be applied safely to patients with mild MG symptoms. How physical exercise affects muscle parameters and risk factors for lifestyle diseases in patients with MG is, however, only poorly known. We evaluated functional skeletal muscle parameters in 11 MG patients, before and after conducting a 12-week supervised physical therapy regimen of aerobic and resistance strength training. After the training program, parameters of the rectus femoris muscle improved: compound motor action potential (from 4.5 ± 2.6 to 5.3 ± 2.8 mV, P = .016), isometric muscle force (from 25.2 ± 4.4 to 30.2 ± 3.8 kg; P = .014), and ultrasound muscle thickness (from 19.6 ± 5.6 to 23.0 ± 3.9 mm, P = .0098) all increased. Further, physical performance based measures improved, including the 30-Second Chair Stand Test (median change +2, P = .0039) as well as the clinical MG composite score [from 3 (2-5) to 2 (0-4), P = .043]. No improvement in muscle function was observed in the biceps brachii muscle. These findings indicate that MG patients can improve their muscular functions by incorporating aerobic and resistance strength training, especially in proximal leg muscles. This is important knowledge when physical therapy is considered for this patient group, for whom no guidelines on physical exercise currently exist.

Evidence-based medicine for every day, everyone, and every therapeutic study

The rapid growth in published medical literature makes it difficult for clinicians to keep up with advances in their fields. This may result in a cursory scan of the abstract and conclusion of a study without critically evaluating study quality. The application of evidence-based medicine (EBM) is the process of converting the abstract task of reading the literature into a practical method of using the literature to inform care in a specific clinical context while simultaneously expanding one's knowledge. EBM involves 4 steps: (1) stating the clinical problem in a defined question; (2) searching the literature for the evidence; (3) critically appraising the evidence for its validity; and (4) applying the evidence in the context of the patient's situation, preferences, and values. In this review, we use the recently published trial of thymectomy in myasthenia gravis as an example and systematically go through the steps of assessing internal validity, precision, and external validity. Muscle Nerve 58: 486-496, 2018.

Quantitative Myasthenia Gravis Score: a Brazilian multicenter study for translation, cultural adaptation and validation

Objective

To perform the translation, cross-cultural adaptation and validation of the Quantitative Myasthenia Gravis Score (QMGS) to Brazilian Portuguese in accordance with international ethical standards.

Methods

The following steps were taken: (1) implementation of the translation protocol and transcultural adaptation, (2) validation of the adapted content, and (3) assessment of reliability. To check intra- and inter-observer reproducibility, each patient underwent two interviews with interviewer-A and one with B. The QMGS was compared to the Myasthenia Gravis Composite Scale and Myasthenia-specific Quality of Life Questionnaire.

Results

Our study group consisted of 30 patients, with a mean age of 47.6±11.4 years and a mean duration of illness of 11.33±8.49 years. Correlation between the QMGS and MGC was very strong (r = 0.928; p < 0.001) and substantial between the QMGS and MG-QOL 15 (r = 0.737; p < 0.001).

Conclusion

The Brazilian Portuguese translation, and validation of the QMGS was successfully performed.

The Role of Osteopontin and Its Gene on Glucocorticoid Response in Myasthenia Gravis

Biomarkers that assess treatment response for patients with the autoimmune disorder, myasthenia gravis (MG), have not been evaluated to a significant extent. We hypothesized the pro-inflammatory cytokine, osteopontin (OPN), may be associated with variability of response to glucocorticoids (GCs) in patients with MG. A cohort of 250 MG patients treated with standardized protocol of GCs was recruited, and plasma OPN and polymorphisms of its gene, secreted phosphoprotein 1 (SPP1), were evaluated. Mean OPN levels were higher in patients compared to healthy controls. Carriers of rs11728697*T allele (allele definition: one of two or more alternative forms of a gene) were more frequent in the poorly GC responsive group compared to the GC responsive group indicating an association of rs11728697*T allele with GC non-responsiveness. One risk haplotype (AGTACT) was identified associated with GC non-responsiveness compared with GC responsive MG group. Genetic variations of SPP1 were found associated with the response to GC among MG patients.

A multicenter prospective observational study on the safety and efficacy of tacrolimus in patients with myasthenia gravis

INTRODUCTION

Several clinical studies using tacrolimus revealed reasonable therapeutic mechanisms and efficacy in patients with myasthenia gravis (MG). However, long-period studies in a large number of patients with MG are limited; therefore, the aim of this study was to investigate the therapeutic efficacies and safety of tacrolimus in patients with MG during a 12-month follow-up period.

METHODS

Tacrolimus was administered to 150 patients with MG who were recruited based on the inclusion criteria. Fifteen medical centers in Korea participated in this study. The efficacy of tacrolimus was assessed using MG composite scales (MGCS) and the prednisolone-sparing effect. And the adverse drug reactions (ADRs) of tacrolimus were monitored in each patient from the beginning of tacrolimus treatment to the end of the follow-up period.

RESULTS

After starting tacrolimus, the 32 patients were affected by ADRs, and consequentially 134 patients of the enrolled patients were followed up for 12months. They showed that the mean prednisolone dosage significantly decreased (6.1±7.6mg/day), compared to that in the baseline (11.3±9.5mg/day), and MGCS significantly improved after 12months of tacrolimus treatment, compared to that at the baseline.

CONCLUSIONS

Our study showed that tacrolimus would be an effective immunosuppressant as an initial therapeutic agent in patients with MG; in addition, it showed tolerable safety profiles during the 12-month follow-up evaluation.

Exercise in myasthenia gravis: A feasibility study of aerobic and resistance training

INTRODUCTION

It has not been established whether progressive resistance training (PRT) and aerobic training (AT) are feasible and efficient in myasthenia gravis (MG).

METHODS

Fifteen subjects with generalized MG (Myasthenia Gravis Foundation of America (MGFA) clinical classification II-IV) were randomly assigned to 20 training sessions during 8 weeks of either PRT or AT. Feasibility was evaluated based on adherence, drop-out rate, adverse events, and Quantitative Myasthenia Gravis (QMG) score.

RESULTS

Twelve subjects (MGFA II, n = 11; MGFA III, n=1) completed the intervention with a mean adherence of 95 % ± 8. One dropout (PRT) could potentially be related to PRT. Both groups reported adverse events, including bulbar symptoms (n = 2) and increased fatigue (n = 3), but no change in QMG score was observed in either group. The PRT group showed increases in maximal strength and functional capacity.

CONCLUSIONS

Eight weeks of moderate to high intensity AT and PRT were feasible for most patients with mild MG. Maximal strength and functional capacity increased in the PRT group. Muscle Nerve 56: 700-709, 2017.

Neuromuscular junction disorders

Diseases of the neuromuscular junction comprise a wide range of disorders. Antibodies, genetic mutations, specific drugs or toxins interfere with the number or function of one of the essential proteins that control signaling between the presynaptic nerve ending and the postsynaptic muscle membrane. Acquired autoimmune disorders of the neuromuscular junction are the most common and are described here. In myasthenia gravis, antibodies to acetylcholine receptors or to proteins involved in receptor clustering, particularly muscle-specific kinase, cause direct loss of acetylcholine receptors or interfere with the agrin-induced acetylcholine receptor clustering necessary for efficient neurotransmission. In the Lambert-Eaton myasthenic syndrome (LEMS), loss of the presynaptic voltage-gated calcium channels results in reduced release of the acetylcholine transmitter. The conditions are generally recognizable clinically and the diagnosis confirmed by serologic testing and electromyography. Screening for thymomas in myasthenia or small cell cancer in LEMS is important. Fortunately, a wide range of symptomatic treatments, immunosuppressive drugs, or other immunomodulating therapies is available. Future research is directed to understanding the pathogenesis, discovering new antigens, and trying to develop disease-specific treatments.

Activity limitations in myasthenia gravis and relation to clinical variables

INTRODUCTION

It is unknown how fluctuations in muscle weakness affect activity limitations in myasthenia gravis patients and how the severity of these limitations compares with published data on other neuromuscular disorders (NMD).

METHODS

In this study we analyzed ACTIVLIM (acronym of "ACTIVity LIMitations") and quantitative myasthenia gravis (QMG) scores. We assessed the impact of QMG and other clinical variables on ACTIVLIM, using B coefficients.

RESULTS

The mean ACTIVLIM score in 118 MG patients was 3.3. There was a correlation between QMG and ACTIVLIM (B coefficient = -0.206, P < 0.001) and between changes in both scores (B coefficient = -0.175, P = 0.002). Men and patients without another autoimmune disease had a better ACTIVLIM score (B coefficient = 0.785, P = 0.015 and B coefficient = 0.998, P = 0.008, respectively).

CONCLUSIONS

The ACTIVLIM score in MG is higher than in other NMD. Fluctuations in QMG correlated significantly with changes in ACTIVLIM. Muscle Nerve 56: 64-70, 2017.

Response to treatment of myasthenia gravis according to clinical subtype

Background

We have previously reported using two-step cluster analysis to classify myasthenia gravis (MG) patients into the following five subtypes: ocular MG; thymoma-associated MG; MG with thymic hyperplasia; anti-acetylcholine receptor antibody (AChR-Ab)-negative MG; and AChR-Ab-positive MG without thymic abnormalities. The objectives of the present study were to examine the reproducibility of this five-subtype classification using a new data set of MG patients and to identify additional characteristics of these subtypes, particularly in regard to response to treatment.

Methods

A total of 923 consecutive MG patients underwent two-step cluster analysis for the classification of subtypes. The variables used for classification were sex, age of onset, disease duration, presence of thymoma or thymic hyperplasia, positivity for AChR-Ab or anti–muscle-specific tyrosine kinase antibody, positivity for other concurrent autoantibodies, and disease condition at worst and current. The period from the start of treatment until the achievement of minimal manifestation status (early-stage response) was determined and then compared between subtypes using Kaplan-Meier analysis and the log-rank test. In addition, between subtypes, the rate of the number of patients who maintained minimal manifestations during the study period/that of patients who only achieved the status once (stability of improved status) was compared.

Results

As a result of two-step cluster analysis, 923 MG patients were classified into five subtypes as follows: ocular MG (AChR-Ab-positivity, 77%; histogram of onset age, skewed to older age); thymoma-associated MG (100%; normal distribution); MG with thymic hyperplasia (89%; skewed to younger age); AChR-Ab-negative MG (0%; normal distribution); and AChR-Ab-positive MG without thymic abnormalities (100%, skewed to older age). Furthermore, patients classified as ocular MG showed the best early-stage response to treatment and stability of improved status, followed by those classified as thymoma-associated MG and AChR-Ab-positive MG without thymic abnormalities; by contrast, those classified as AChR-Ab-negative MG showed the worst early-stage response to treatment and stability of improved status.

Conclusions

Differences were seen between the five subtypes in demographic characteristics, clinical severity, and therapeutic response. Our five-subtype classification approach would be beneficial not only to elucidate disease subtypes, but also to plan treatment strategies for individual MG patients.

Randomized Trial of Thymectomy in Myasthenia Gravis

BACKGROUND

Thymectomy has been a mainstay in the treatment of myasthenia gravis, but there is no conclusive evidence of its benefit. We conducted a multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone.

METHODS

We compared extended transsternal thymectomy plus alternate-day prednisone with alternate-day prednisone alone. Patients 18 to 65 years of age who had generalized nonthymomatous myasthenia gravis with a disease duration of less than 5 years were included if they had Myasthenia Gravis Foundation of America clinical class II to IV disease (on a scale from I to V, with higher classes indicating more severe disease) and elevated circulating concentrations of acetylcholine-receptor antibody. The primary outcomes were the time-weighted average Quantitative Myasthenia Gravis score (on a scale from 0 to 39, with higher scores indicating more severe disease) over a 3-year period, as assessed by means of blinded rating, and the time-weighted average required dose of prednisone over a 3-year period.

RESULTS

A total of 126 patients underwent randomization between 2006 and 2012 at 36 sites. Patients who underwent thymectomy had a lower time-weighted average Quantitative Myasthenia Gravis score over a 3-year period than those who received prednisone alone (6.15 vs. 8.99, P<0.001); patients in the thymectomy group also had a lower average requirement for alternate-day prednisone (44 mg vs. 60 mg, P<0.001). Fewer patients in the thymectomy group than in the prednisone-only group required immunosuppression with azathioprine (17% vs. 48%, P<0.001) or were hospitalized for exacerbations (9% vs. 37%, P<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (P=0.73), but patients in the thymectomy group had fewer treatment-associated symptoms related to immunosuppressive medications (P<0.001) and lower distress levels related to symptoms (P=0.003).

CONCLUSIONS

Thymectomy improved clinical outcomes over a 3-year period in patients with nonthymomatous myasthenia gravis. (Funded by the National Institute of Neurological Disorders and Stroke and others; MGTX ClinicalTrials.gov number, NCT00294658.).

Subcutaneous Immunoglobulin Therapy in the Chronic Management of Myasthenia Gravis: A Retrospective Cohort Study

BACKGROUND

Immunoglobulin therapy has become a major treatment option in several autoimmune neuromuscular disorders. For patients with Myasthenia Gravis (MG), intravenous immunoglobulin (IVIg) has been used for both crisis and chronic management. Subcutaneous Immunoglobulins (SCIg), which offer the advantage of home administration, may be a practical and effective option in chronic management of MG. We analyzed clinical outcomes and patient satisfaction in nine cases of chronic disabling MG who were either transitioned to, or started de novo on SCIg.

METHODS AND FINDINGS

This was a retrospective cohort study for the period of 2015-2016, with a mean follow-up period of 6.8 months after initiation of SCIg. All patients with MG treated with SCIg at the Ottawa Hospital, a large Canadian tertiary hospital with subspecialty expertise in neuromuscular disorders were included, regardless of MG severity, clinical subtype and antibody status. The primary outcome was MG disease activity after SCIg initiation. This outcome was measured by 1) the Myasthenia Gravis Foundation of America (MGFA) clinical classification, and 2) subjective scales of disease activity including the Myasthenia Gravis activities of daily living profile (MG-ADL), Myasthenia Gravis Quality-of-life (MG-QOL 15), Visual Analog (VA) satisfaction scale. We also assessed any requirement for emergency department visits or hospitalizations. Safety outcomes included any SCIg related complication. All patients were stable or improved for MGFA class after SCIg initiation. Statistically significant improvements were documented in the MG-ADL, MG-QOL and VAS scales. There were no exacerbations after switching therapy and no severe SCIg related complications.

CONCLUSIONS

SCIg may be a beneficial therapy in the chronic management of MG, with favorable clinical outcome and patient satisfaction results.

Precision medicine in myasthenia graves: begin from the data precision

Myasthenia gravis (MG) is a prototypic autoimmune disease with overt clinical and immunological heterogeneity. The data of MG is far from individually precise now, partially due to the rarity and heterogeneity of this disease. In this review, we provide the basic insights of MG data precision, including onset age, presenting symptoms, generalization, thymus status, pathogenic autoantibodies, muscle involvement, severity and response to treatment based on references and our previous studies. Subgroups and quantitative traits of MG are discussed in the sense of data precision. The role of disease registries and scientific bases of precise analysis are also discussed to ensure better collection and analysis of MG data.

Quantitative motor assessment of muscular weakness in myasthenia gravis: a pilot study

BACKGROUND

Muscular weakness in myasthenia gravis (MG) is commonly assessed using Quantitative Myasthenia Gravis Score (QMG). More objective and quantitative measures may complement the use of clinical scales and might detect subclinical affection of muscles. We hypothesized that muscular weakness in patients with MG can be quantified with the non-invasive Quantitative Motor (Q-Motor) test for Grip Force Assessment (QGFA) and Involuntary Movement Assessment (QIMA) and that pathological findings correlate with disease severity as measured by QMG.

METHODS

This was a cross-sectional pilot study investigating patients with confirmed diagnosis of MG. Data was compared to healthy controls (HC). Subjects were asked to lift a device (250 and 500 g) equipped with electromagnetic sensors that measured grip force (GF) and three-dimensional changes in position and orientation. These were used to calculate the position index (PI) and orientation index (OI) as measures for involuntary movements due to muscular weakness.

RESULTS

Overall, 40 MG patients and 23 HC were included. PI and OI were significantly higher in MG patients for both weights in the dominant and non-dominant hand. Subgroup analysis revealed that patients with clinically ocular myasthenia gravis (OMG) also showed significantly higher values for PI and OI in both hands and for both weights. Disease severity correlates with QIMA performance in the non-dominant hand.

CONCLUSION

Q-Motor tests and particularly QIMA may be useful objective tools for measuring motor impairment in MG and seem to detect subclinical generalized motor signs in patients with OMG. Q-Motor parameters might serve as sensitive endpoints for clinical trials in MG.

Diurnal and day-to-day variation of isometric muscle strength in myasthenia gravis

INTRODUCTION

In patients with myasthenia gravis (MG), muscle strength is expected to decrease gradually during the day due to physical activities.

METHODS

Isometric muscle strength at the shoulder, knee, and ankle was determined in 10 MG patients (MGFA class II-IV) who were receiving usual medical treatment and in 10 control subjects. To determine diurnal and day-to-day variation, muscle strength was measured 4 times during day 1 and once at day 2.

RESULTS

Knee extension strength decreased during the day in both patients and controls. Neither diurnal nor day-to-day variation of muscle strength was higher in patients compared with controls.

CONCLUSIONS

Patients with mild to moderate MG did not have increased variation of isometric muscle strength during the day or from day-to-day compared with controls. This suggests that isometric muscle performance can be determined with high reproducibility in similar groups of MG patients without regard to time of day.

The clinical absolute and relative scoring system-a quantitative scale measuring myasthenia gravis severity and outcome used in the traditional Chinese medicine

Myasthenia gravis (MG) is a chronic autoimmune disease caused by autoantigen against the nicotine acetylcholine receptor at the neuromuscular junction. With modern treatment facilities, the treatment effect and outcome for MG has been greatly improved with MG and non-MG patients enjoying the same life expectancy. Many classifications of disease distribution and severity have been set up and tested all over the world, mainly in the western world. However, the absolute and relative scoring system for evaluating the severity and treatment effect of MG in China where traditional Chinese medicine (TCM) has been practiced for thousands of years has not been introduced worldwide. The TCM has achieved a great success in the treatment of MG in the country with a huge population. This article serves to introduce this scoring system to the world.

Acetylcholinesterase inhibitor treatment for myasthenia gravis

BACKGROUND

In myasthenia gravis, antibody-mediated blockade of acetylcholine receptors at the neuromuscular junction abolishes the naturally occurring 'safety factor' of synaptic transmission. Acetylcholinesterase inhibitors provide temporary symptomatic treatment of muscle weakness but there is controversy about their long-term efficacy, dosage and side effects. This is the second update of a review published in The Cochrane Library Issue 2, 2011.

OBJECTIVES

To evaluate the efficacy of acetylcholinesterase inhibitors in all forms of myasthenia gravis.

SEARCH METHODS

On 8 July 2014 we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE and EMBASE for randomised controlled trials and quasi-randomised controlled trials regarding usage of acetylcholinesterase inhibitors in myasthenia gravis. Two authors scanned the articles for any study eligible for inclusion. We also contacted the authors and known experts in the field to identify additional published or unpublished data and searched clinical trials registries for ongoing trials.

SELECTION CRITERIA

The types of studies were randomised or quasi-randomised trials. Participants were myasthenia gravis patients diagnosed by an internationally accepted definition. The intervention was treatment with any form of acetylcholinesterase inhibitor. Types of outcome measures Primary outcome measureImprovement in the presenting symptoms within one to 14 days of the start of treatment. Secondary outcome measures(1) Improvement in the presenting symptoms more than 14 days after the start of treatment.(2) Change in impairment measured by a recognised and preferably validated scale, such as the quantitative myasthenia gravis score, within one to 14 days and more than 14 days after the start of treatment.(3) Myasthenia Gravis Association of America post-intervention status more than 14 days after start of treatment.(4) Adverse events including muscarinic side effects.

DATA COLLECTION AND ANALYSIS

One author (MMM) extracted the data, which were checked by a second author. We contacted study authors for extra information and collected data on adverse effects from the trials.

MAIN RESULTS

We did not find any large randomised or quasi-randomised trials of acetylcholinesterase inhibitors in generalised myasthenia gravis either for the first version of this review or this update. One cross-over randomised trial using intranasal neostigmine in a total of 10 participants was only available as an abstract. It included three participants with ocular myasthenia gravis and seven with generalised myasthenia gravis. Symptoms of myasthenia gravis (measured as improvement in at least one muscle function) improved in nine of the 10 participants after the two-week neostigmine treatment phase. No participant improved after the placebo phase. Lack of detail in the report meant that the risk of bias was unclear. Adverse events were minor.

AUTHORS' CONCLUSIONS

Except for one small and inconclusive trial of intranasal neostigmine, no other randomised controlled trials have been conducted on the use of acetylcholinesterase inhibitors in myasthenia gravis. The response to acetylcholinesterase inhibitors in observational studies is so clear that a randomised controlled trial depriving participants in a placebo arm of treatment would be difficult to justify.

Effects of balance strategy training in myasthenia gravis: a case study series

INTRODUCTION

Studies of exercise in patients with myasthenia gravis (MG) are sparse. Balance strategy training (BST) multimodal exercise has proven efficacy in adults for enhancing balance and functional mobility. This prospective study aims to determine if BST improves functional ability and balance in people with MG.

METHODS

Seven individuals with MG participated in a 16-session workstation intervention. Repeated measures (pre/post-intervention and 4-week follow-up) consisting of quantitative myasthenia gravis score (QMG), 6-minute walk test (6MWT), timed up and go (TUG) with dual task (TUG(manual) and TUG(cognitive)), and standing stability on foam with eyes closed (foamEC) were assessed.

RESULTS

Most measurements showed sustained improvement at follow-up. QMG, TUG(cognitive), and foam EC achieved clinically significant improvements (>15%). No adverse effects were reported.

CONCLUSIONS

BST was effective in improving balance and QMG scores in subjects with MG. A multimodal BST approach is thus suggested to target different aspects of balance and functional mobility.

Prognostic factors and health-related quality of life in ocular Myasthenia Gravis (OMG)

We evaluate the factors predictive of prognosis in 91 Caucasian patients affected by ocular myasthenia gravis (OMG), followed at our Institution during an observational time, ranging from 12 to 240 months. The Myasthenia Gravis Foundation of America (MGFA) clinical classification was used to grade the disease severity. We considered as outcome measures the variation in two subscores, ocular (O-QMG) and nonocular (NO-QMG); the last one reflected bulbar, neck, extremity functions. None of the independent variables evaluated for association with the outcome, as age of onset, type of therapy, length of interval between first and last examinations, and presence of antibodies to acetylcholine receptors (AChR-Abs) significantly affected the evolution of O-QMG and of NO-QMG. Health-related quality of life (HRQol) was assessed in 63 patients. Variations of diplopia or ptosis did not affect significantly physical (PCS) or mental composite subscores (MCS) of the Short-Form Health Survey (SF-36). Human leukocyte antigen (HLA) genotyping was studied to explore whether HLA class I and II allelic distribution differed among MG patients and controls. None of the studied HLA alleles significantly differed between OMG patients and controls. Similarly, none of the alleles with frequencies higher than 15% either in OMG patients or in controls was significantly associated, after Bonferroni correction, with the presence or absence of anti-AChR-Abs in serum.

The MG composite: an outcome measure for myasthenia gravis for use in clinical trials and everyday practice

The myasthenia gravis composite (MGC) was constructed by selecting the best performing items from three commonly used, MG-specific scales. The response categories of the items were subsequently weighted for importance. The MGC, which takes less than five minutes to complete, is made up of three ocular, three bulbar, one respiratory, one neck, and two limb items. After its construction, the MGC was validated in an 11-center scale validity study. During the validation study, which included test-retest analysis, it was determined that a 3-point improvement in MGC score reliably indicates clinical improvement. A 3-point improvement in MGC also appears to be meaningful to the patient. Rasch analysis of the MGC confirmed that all 10 items belong and can be summed to provide a total score, and that the weights given to the response categories of the items are appropriate.

A mutation causes MuSK reduced sensitivity to agrin and congenital myasthenia

Congenital myasthenic syndromes (CMSs) are a heterogeneous group of genetic disorders affecting neuromuscular transmission. The agrin/muscle-specific kinase (MuSK) pathway is critical for proper development and maintenance of the neuromuscular junction (NMJ). We report here an Iranian patient in whom CMS was diagnosed since he presented with congenital and fluctuating bilateral symmetric ptosis, upward gaze palsy and slowly progressive muscle weakness leading to loss of ambulation. Genetic analysis of the patient revealed a homozygous missense mutation c.2503A>G in the coding sequence of MUSK leading to the p.Met835Val substitution. The mutation was inherited from the two parents who were heterozygous according to the notion of consanguinity. Immunocytochemical and electron microscopy studies of biopsied deltoid muscle showed dramatic changes in pre- and post-synaptic elements of the NMJs. These changes induced a process of denervation/reinnervation in native NMJs and the formation, by an adaptive mechanism, of newly formed and ectopic NMJs. Aberrant axonal outgrowth, decreased nerve terminal ramification and nodal axonal sprouting were also noted. In vivo electroporation of the mutated MuSK in a mouse model showed disorganized NMJs and aberrant axonal growth reproducing a phenotype similar to that observed in the patient's biopsy specimen. In vitro experiments showed that the mutation alters agrin-dependent acetylcholine receptor aggregation, causes a constitutive activation of MuSK and a decrease in its agrin- and Dok-7-dependent phosphorylation.

Artesunate for severe acute Plasmodium falciparum infection in a patient with myasthenia gravis

We report a case of severe malaria in a patient with underlying myasthenia gravis who was successfully treated with artesunate. The outcome was favorable. Artesunate seems to be a good option for patients with underlying myasthenia gravis disease because they benefit from a better toxicity profile than quinine.

The quantitative myasthenia gravis score: comparison with clinical, electrophysiological, and laboratory markers

OBJECTIVE

To determine whether the quantitative myasthenia gravis score (QMGS) accurately represents disease severity in patients with myasthenia gravis (MG).

METHODS

One hundred thirty-five patients with MG from 2 previous randomized studies were included. QMGS correlation with the Myasthenia Gravis Foundation of America (MGFA) score, quality of life scale, acetylcholine receptor antibodies (AChRAbs), and electrophysiological parameters was studied.

RESULTS

The QMGS showed a good correlation with the MGFA scale (r² = 0.54, P < 0.0001), jitter (rs = 0.40, P < 0.0001), and 15-item quality of life scale (rs = 0.41, P = 0.007) and was less well correlated with the 60-item myasthenia gravis-specific quality of life survey and other electrophysiological markers. No correlation was demonstrated with AchRAb titers, but AchRAb-positive patients had higher QMGS (14.2 ± 4.5) than AchRAb-negative patients (12.0 ± 3.7, P = 0.008).

CONCLUSIONS

These results demonstrate that the QMGS is a valid marker for disease severity as shown by the MGFA scale, quality of life scale, and jitter, supporting the use of the QMGS as a primary outcome measure in clinical trials of MG.

Comparison of IVIg and PLEX in patients with myasthenia gravis

OBJECTIVE

Both IV immunoglobulin (IVIg) and plasma exchange (PLEX) are immunomodulatory treatments used to treat patients with myasthenia gravis (MG), but the choice of which treatment to administer to patients is limited due to lack of evidence from adequately powered, masked, randomized, standardized trials.

METHODS

We randomized 84 patients with moderate to severe MG defined as a Quantitative Myasthenia Gravis Score for disease severity (QMGS) of >10.5 and worsening weakness to IVIg (Gamunex®, Talecris Biotherapeutics) 1 g/kg/day for 2 consecutive days or PLEX (Caridian Spectra) 1.0 plasma volume exchanges for 5 exchanges. The patients were evaluated at day 14 after treatment for the primary efficacy parameter of change in QMGS and secondary clinical and electrophysiologic parameters and were followed for a total of 60 days.

RESULTS

Both IVIg and PLEX reduced the QMGS, and IVIg was comparable to PLEX in efficacy. The dropout rate was the same for both treatment arms and both treatments were well-tolerated. The presence of acetylcholine receptor antibodies and greater baseline disease severity predicted a better response to therapy. The postintervention status revealed that the same proportion of patients improved with treatment: 69% on IVIg and 65% on PLEX. The duration of improvement was similar with both treatments.

CONCLUSIONS

IVIg has comparable efficacy to PLEX in the treatment of patients with moderate to severe MG. Both treatments are well-tolerated, and the duration of effect is comparable. Either treatment may be offered to patients depending on availability of resources.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that IVIg and PLEX have comparable efficacy and are equally tolerated in adult patients with moderate to severe MG within 2 weeks of treatment.

Acetylcholinesterase inhibitor treatment for myasthenia gravis

BACKGROUND

In myasthenia gravis, antibody-mediated blockade of acetylcholine receptors at the neuromuscular junction abolishes the naturally occurring 'safety factor' of synaptic transmission. Acetylcholinesterase inhibitors provide temporary symptomatic treatment of muscle weakness, but there is controversy about their long-term efficacy, dosage and side effects.

OBJECTIVES

To evaluate the efficacy of acetylcholinesterase inhibitors in all forms of myasthenia gravis.

SEARCH STRATEGY

We searched The Cochrane Neuromuscular Disease Group Specialized Register (5 October 2009), The Cochrane Central Register of Controlled Trials CENTRAL) (The Cochrane Library Issue 3, 2009), MEDLINE (January 1966 to September 2009), EMBASE (January 1980 to September 2009) for randomised controlled trials and quasi-randomised controlled trials regarding usage of acetylcholinesterase inhibitors in myasthenia gravis. Two authors scanned the articles for any study eligible for inclusion. We also contacted the authors and known experts in the field to identify additional published or unpublished data.

SELECTION CRITERIA

Types of studies: all randomised or quasi-randomised trials.

TYPES OF PARTICIPANTS

all myasthenia gravis patients diagnosed by an internationally accepted definition.Types of interventions: treatment with any form of acetylcholinesterase inhibitor.Types of outcome measuresPrimary outcome measureImprovement in the presenting symptoms within 1 to 14 days of the start of treatment.Secondary outcome measures(1) Improvement in the presenting symptoms more than 14 days after the start of treatment.(2) Change in impairment measured by a recognised and preferably validated scale, such as the quantitative myasthenia gravis score within 1 to 14 days and more than 14 days after the start of treatment.(3) Myasthenia Gravis Association of America post-intervention status more than 14 days after start of treatment.(4) Adverse events: muscarinic side effects.

DATA COLLECTION AND ANALYSIS

One author (MMM) extracted the data, which were checked by a second author. We contacted study authors for extra information and collected data on adverse effects from the trials.

MAIN RESULTS

We did not find any large randomised or quasi-randomised trials of acetylcholinesterase inhibitors in generalised myasthenia gravis. One cross-over randomised trial using intranasal neostigmine in a total of 10 subjects was only available as an abstract.

AUTHORS' CONCLUSIONS

Except for one small and inconclusive trial of intranasal neostigmine, no randomised controlled trial has been conducted on the use of acetylcholinesterase inhibitors in myasthenia gravis. Response to acetylcholinesterase inhibitors in observational studies is so clear that a randomised controlled trial depriving participants in the placebo arm of treatment would be difficult to justify.

IVIG treatment for myasthenia gravis: effectiveness, limitations, and novel therapeutic strategies

Acquired myasthenia gravis (MG) is an autoimmune disorder treated with cholinesterase inhibitors and a number of immunotherapies. Intravenous immunoglobulin (IVIG) is an expensive and commonly used immunotherapy for patients with an exacerbation of MG, but its effectiveness has only recently been demonstrated in a randomized clinical trial. This paper describes the study design, results, and limitations of a double-blind, randomized, placebo-controlled trial designed to definitively determine if IVIG benefits patients with MG who present with worsening weakness. Fifty-one patients with worsening weakness due to MG were randomized to receive either 2 g/kg of IVIG over 2 days or an equivalent volume of placebo (5% dextrose in water). The Quantitative MG Score (QMG Score) for Disease Severity, a validated clinical composite scale and the primary outcome measure in the study, was calculated by a masked observer 14 and 28 days after treatment. Patients treated with IVIG demonstrated a significant improvement in QMG Score for Disease Severity at day 14 and the response persisted at day 28. The largest clinical improvement occurred in patients with more severe disease. IVIG was well tolerated with no significant side effects observed. Given the observed efficacy and safety of IVIG demonstrated in this trial, future studies are necessary to determine if there is a role for interval IVIG treatments in chronic MG.