Validation of the Besta Neurological Institute rating scale for myasthenia gravis

Therapeutic challenges and unmet needs in the management of myasthenia gravis: an Italian expert opinion

Myasthenia gravis (MG) is a rare, autoimmune, neurological disorder. Most MG patients have autoantibodies against acetylcholine receptors (AChRs). Some have autoantibodies against muscle-specific tyrosine kinase (MuSK) or lipoprotein-receptor-related protein 4 (LRP4), and some are seronegative. Standard of care, which includes anti-cholinesterase drugs, thymectomy, corticosteroids (CS), and off-label use of non-steroidal immunosuppressive drugs (NSISTs), is bounded by potential side effects and limited efficacy in refractory generalized MG (gMG) patients. This highlights the need for new therapeutic approaches for MG. Eculizumab, a monoclonal antibody that inhibits the complement system, has been recently approved in Italy for refractory gMG. A panel of 11 experts met to discuss unmet therapeutic needs in the acute and chronic phases of the disease, as well as the standard of care for refractory patients. Survival was emphasized as an acute phase outcome. In the chronic phase, persistent remission and early recognition of exacerbations to prevent myasthenic crisis and respiratory failure were considered crucial. Refractory patients require treatments with fast onset of action, improved tolerability, and the ability to slow disease progression and increase life expectancy. The Panel agreed that eculizumab would presumably meet the therapeutic needs of many refractory gMG patients. The panel concluded that the unmet needs of current standard of care treatments for gMG are significant. Evaluating new therapeutic options accurately is essential to find the best balance between efficacy and tolerability for each patient. Collecting real-world data on novel molecules in routine clinical practice is necessary to address unmet needs.

275th ENMC international workshop: Seronegative myasthenia gravis: An update paradigm for diagnosis and management, 9-11 February 2024, Hoofddorp, the Netherlands

The 275th ENMC workshop on the diagnosis and management of seronegative myasthenia gravis (SNMG) was held on February 9-11, 2024. The participants included experts in the field of adult and pediatric MG together with patient representatives. This workshop aimed to redefine SNMG in view of recent diagnostic and therapeutic updates and to identify patient unmet needs. The workshop has highlighted considerable challenges in the SNMG diagnostic work-up. To date, SNMG confirmation is often controversial, given the absence of specific diagnostic tests; no recommendations from international panels of experts are available in literature; myopathies, congenital myasthenic syndromes and functional disorders are the commonest misdiagnoses. Improving the disease diagnosis is crucial to avoid long delays in receiving appropriate treatment. To this purpose, a comprehensive diagnostic algorithm achieved consensus. Moreover, a remarkable variability in SNMG response to therapy and long-term prognosis has also been highlighted.

Novel DPAGT1 Gene Mutation in Two Twins with Congenital Myasthenic Syndrome and a Review of the Literature

Congenital myasthenic syndromes (CMS) are rare diseases caused by mutation in genes coding for proteins involved in neuromuscular junction structure and function. DPAGT1 gene mutations are a rare cause of CMS whose clinical evolution and pathophysiological mechanisms have not been clarified completely. We present the case of two twins displaying an infancy-onset predominant limb-girdle phenotype and carrying a novel DPAGT1 mutation associated with unusual histological and clinical findings. CMS can mimic paediatric and adult limb-girdle phenotype, hence neurophysiology plays a fundamental role in the differential diagnosis.

Validation of the Italian version of the Myasthenia Gravis Impairment Index (MGII)

Objective

To validate the Italian version of the Myasthenia Gravis Impairment Index (MGII).

Introduction

MGII is a recent promising measure developed for MG patient evaluation. It includes a clinical severity evaluation and a patient-reported questionnaire. It has been developed in English and has demonstrated feasibility, reliability, and construct validity. Recently, its Dutch translation has been validated.

Methods

MGII was translated to Italian with a multi-step forward process. We assessed correlations with the following scores: Istituto Nazionale Carlo Besta score for Myasthenia Gravis (INCB-MG), the MG Activities of Daily Living (MG-ADL), the Myasthenia Gravis Composite (MGC), the Quality of Life 15 for Myasthenia Gravis (QOL15-MG), and the Myasthenia Gravis Disability (MGDIS). We also assessed differences in MGII scores by disease severity with the ANOVA Kruskal–Wallis test.

Results

One hundred forty-one patients were enrolled. The mean MGII total score was 13.3 ± 11.9 (range 0–49), with a mean ocular subscore of 3.7 ± 4.7 and a mean MGII generalized subscore of 9.6 ± 9.0. As expected, the MGII had a good correlation with the other severity scores. The MGII had a lower floor effect (3.5%) than the other measures. Twenty-five patients were assessed in follow-up; as expected, the MGII change scores had moderate correlations with change in other MG severity measures and lower correlations with quality of life measures.

Conclusions

The MGII score was cross-culturally validated in an Italian cohort of MG patients. We confirmed its lower floor effect and the correlations with other MG measures including INCB-MG that was not evaluated in previous studies.

Measuring Clinical Treatment Response in Myasthenia Gravis

In this article we provide an overview of health-related outcome measurement-to better understand what different outcomes used in myasthenia actually measure-and to provide some guidance when choosing measures based on the clinical context and question. In myasthenia, the most commonly used outcome measures are aimed at assessing the signs and symptoms. In this review, we provide a summary of the most commonly used outcome measures. We discuss instruments that gauge disease overall health impact, such as on disability and quality of life. Finally, we discuss other relevant outcomes such as steroid-sparing effects and the role of surrogate markers.

Italian recommendations for the diagnosis and treatment of myasthenia gravis

Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.

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.

Validity, reliability, and sensitivity to change of the myasthenia gravis activities of daily living profile in a sample of Italian myasthenic patients

The purpose of this study is to report on the validity, reliability, and sensitivity of the myasthenia gravis activities of daily living profile (MG-ADL) in a sample of Italian patients. Patients with myasthenia gravis (MG) completed a protocol that included the MG-ADL, the WHO Disability Assessment Schedule (WHODAS 2.0), the Besta Neurological Institute rating scale for myasthenia gravis, and the MG-composite. Cronbach's alpha was used to test reliability, Spearman's correlation and intra-class correlation coefficient (ICC) to test short-term test-retest, Kruskal-Wallis test to assess differences in MG-ADL between patients with different disease severity, and Wilcoxon signed-rank test to assess sensitivity to change. In total, 58 patients were enrolled: 44 were females, mean MG duration 10.5 ± 10.4 years, mean MG-ADL 3.98 ± 3.07. The MG-ADL showed good internal consistency (alpha = .774), stability (test-retest correlation = .98, ICC = .97). It was superior to the WHODAS 2.0 in differentiating patients with different MG type and severity (P < .001), it showed higher sensitivity to change (P = .001 for improved and P = .007 for worsened patients) and higher correlation with the MG-composite (RHO = .625). Our analysis shows that the Italian version of the MG-ADL is valid, reliable, stable, and sensitive to change.

A propensity score analysis for comparison of T-3b and VATET in myasthenia gravis

Objective:

We performed propensity score (PS) models to compare the outcome of patients with myasthenia gravis (MG) submitted to 2 different surgical approaches: extended transsternal (T-3b) or thoracoscopic extended thymectomy (VATET).

Methods:

Patients' clinical data were retrieved from the MG database of the C. Besta Neurologic Institute Foundation. In the PS analysis, a matching ratio of 1:1 of the main clinical variables was obtained for the 2 groups of patients and treatment effect was estimated by comparing their outcome.

Results:

A total of 210 patients met the inclusion criteria, by having a complete set of clinical data, and were included in the PS model; a matched dataset of 122 participants (61 per group) showed an adequate balance of all the covariates. Our analysis demonstrated that 68.9% of patients who had thymectomy by the VATET technique reached the pharmacologic remission/remission status at 2 years from thymectomy compared to 34.4% of those operated on by the T-3b technique (p < 0.001), had a lower INCB-MG score (p < 0.001), and had less muscle fatigability (p = 0.004). Similar results were found considering only nonthymomatous patients with MG. Results were also confirmed by paired statistical tests.

Conclusions:

Our PS matching analysis showed that VATET is a reliable and effective surgical approach alternative to T-3b in patients with MG who are candidates for thymectomy.

Classification of evidence:

This study provides Class IV evidence that for patients with MG, VATET is more effective than T-3b thymectomy.