Clinical characteristics of autoimmune disorders in the central nervous system associated with myasthenia gravis

Inebilizumab treatment in a patient with co-occurring AQP4-IgG positive neuromyelitis optica spectrum disorder and myasthenia gravis: a case report and literature review

Objective

This study aims to delineate the clinical features underlying the concurrent disease of neuromyelitis optica spectrum disorder (NMOSD) and myasthenia gravis (MG), and to identify efficacious therapeutic strategies.

Background

NMOSD and MG are uncommon autoimmune diseases that infrequently co-exist. Despite previous reports, a consensus on treating NMOSD concurrent with MG is lacking.

Methods

We present the case of a 55-year-old female with both anti-aquaporin-4 (AQP4) antibody-positive NMOSD and anti-acetylcholine receptor (AChR) antibody-positive MG, who achieved stable disease control following treatment with inebilizumab without significant adverse effects. We also conducted a literature review to evaluate the clinical profile of this comorbidity.

Results

Our review identified 85 patients with concurrent NMOSD and MG. In 70 well-documented cases, MG predated NMOSD in 60 (85.8%) cases, with 42 (70%) patients having undergone thymectomy. Six (8.6%) patients were first diagnosed with NMOSD, and then thymectomy was performed in 2 (33.3%) MG patients. For NMOSD treatment, although most patients received steroid hormones and immunosuppressive agents, quite a few patients had persistent severe disability. Additionally, of 44 patients with clear records of disease recurrence, 31 patients(70.5%) experienced frequent relapses of optic neuritis and myelitis, ranging from 1 to 15 attacks, averaging five. The manifestations of MG are mainly included fatigability, diplopia, and blepharoptosis, with symptoms well-controlled in most patients. Our patient treated with inebilizumab for 1 year and no relapse was recorded to date.

Conclusions

Though MG typically precedes NMOSD and thymectomy is frequently performed, it is not a prerequisite for NMOSD development but may represent a potential risk factor. MG generally follows a benign course, in contrast to the more aggressive nature of NMOSD. The utility of biological agents such as inebilizumab for patients with both NMOSD combined with MG warrants further attention.

The relationship between neuromyelitis optica spectrum disorder and autoimmune diseases

Objective

There have been reports of neuromyelitis optica spectrum disorder (NMOSD) coexisting with connective tissue disorders. The objective of this study was to describe the characteristics of NMOSD coexisting with autoimmune diseases (AID).

Methods

This retrospective study evaluated NMOSD patients with and without AID. The enrolled patients had at least one attack, with duration of more than 1 year. Data on the demographics, clinical features, and laboratory findings were assessed. The Poisson model was used to investigate the risk factors associated with the annualized relapse rate (ARR), whereas the Cox model was used to evaluate the risk factors for the first relapse.

Results

A total of 180 patients (154 women and 26 men) with NMOSD were identified: 45 had AID and 135 did not. Female patients had a higher prevalence of concomitant AID (p = 0.006) and a greater relapse rate within the first year. There were no statistically significant differences in the characteristics of patients. Kaplan-Meier analysis revealed that NMOSD patients with seropositive aquaporin 4 antibodies (AQP4-Ab; log-rank: p = 0.044), had a shorter time to relapse. Patients seropositive for AQP4-Ab (HR = 2.402, 95%CI = 1.092-5.283, p = 0.029) had a higher risk of suffering a first relapse, according to the Cox model. Patients with and without AID showed a similar declining tendency in terms of change in ARR throughout the first 5 years of the disease. The ARR was greater in the first year [incidence rate ratio (IRR) = 1.534, 95%CI = 1.111-2.118] and the first 2 years (IRR = 1.474, 95%CI = 1.056-2.058) in patients with coexisting AID diagnosis prior to the NMOSD onset.

Conclusions

Patients with NMOSD with coexisting AID had similar characteristics when compared with those without AID. NMOSD patients with AID diagnosed before onset had a higher risk of relapse in the early stage of the disease.

Neurometabolic and Brain Functional Alterations Associated with Cognitive Impairment in Patients with Myasthenia Gravis: A Combined 1H-MRS and fMRI Study

Whether patients with myasthenia gravis (MG) exhibit cognitive impairment is controversial. Also the underlying mechanisms are unknown. We aimed to investigate alterations in cognitive function, neurometabolite levels, and brain function in patients with MG and to explore the associations between abnormal regional brain functional activity, neurometabolite concentrations in the MPFC and left thalamus, and cognitive activity in patients with MG. Neuropsychological tests, proton magnetic resonance spectroscopy, and resting-state functional magnetic resonance imaging were performed on 41 patients with MG and 45 race-, sex-, age-, and education-matched healthy controls (HCs). The results suggest that MG is accompanied by cognitive decline, as indicated by global cognitive function, visual-spatial function, language, memory, abnormalities in regional brain functional activity, and neurometabolite alterations (including GABA, NAA, and Cho) in the medial prefrontal cortex (MPFC) and left thalamus. Cognitive impairment in patients with MG may be related to abnormal regional brain functional activity and changes in neurometabolites, and regional brain functional activity may be modulated by specific neurometabolites.

Association between myasthenia gravis and cognitive disorders: a PRISMA-compliant meta-analysis

OBJECTIVE

This meta-analysis assessed the association between myasthenia gravis (MG) and cognitive disorders.

METHODS

The PubMed, Web of Science, OVID, EMBASE, CNKI and Wanfang electronic databases were comprehensively searched from inception to October 2020 for relevant studies. The primary outcomes were scores of the cognitive function battery. A random effects model was used to evaluate the cognitive function of patients with MG.

RESULTS

Eight cross-sectional studies containing 381 patients and 220 healthy controls were included in this meta-analysis. In relation to global cognitive function, patients with MG performed significantly worse than healthy individuals (SMD = -0.4, 95% CI = -0.63 to -0.16, p < 0.001, I2 = 10%). Specifically, the impaired cognitive domains included language, visuospatial function, information processing, verbal immediate and delayed recall memory, visual immediate recall memory, and response fluency, while attention, executive function, and visual delayed recall memory were unimpaired. The patients with early-onset (SMD= -0.527, 95% CI = -0.855 to -0.199, p = 0.002) and generalized MG (SMD= -0.577, 95% CI = -1.047 to -0.107, p = 0.016) had poorer global cognitive performance than the healthy population.

CONCLUSIONS

Patients with MG may have cognitive disorders, including those associated with the domains of language, visuospatial function, information processing, verbal immediate and delayed recall memory, visual immediate recall memory and response fluency. Furthermore, the age of onset and disease severity may be associated with cognitive disorders in patients with MG.

Cross-syndrome: myasthenia gravis and the demyelinating diseases of the central nervous system combination. Systematic literature review and case reports

Nowadays the problem of comorbidity is still relevant. In this review, we describe clinical cases of the disease of the neuromuscular junction (myasthenia gravis (MG) generalized form) and the demyelinating disease of the central nervous system (DD CNS) (multiple sclerosis, neuromyelitis optica spectrum disorder (NMOSD), etc.) combinations registered in our practice with precise pathogenetic analysis. Although the number of the described associations is growing every year, the exact development mechanisms of this cross syndrome as well as the nature of the association between the discussed autoimmune diseases remain unknown. At the beginning of both disorders there is a considerable loss of auto tolerance of the immune system and, as a result, an increased response from autoreactive T-lymphocytes to the structures of the nervous system: brain cells and neuromuscular synapses. There are three main theories for comorbidity: initial predisposition, direct case relationship with disease-modifying therapy (DMT) application, and coincidence. It is known that early diagnostics of MG and timely administration of necessary adequate treatment reduce the risk of process generalization and lead to a decline in mortality. Therefore, the offer to examine MS patients with atypical symptoms for possible MG identification seems very rational. Similarly, MG patients having uncharacteristic symptoms that can be indicative of other autoimmune nervous system diseases also demand special diagnostics. Considering the presence of similar pathogenetic links, several authors propose a possibility of a new nosological unit establishment, including described comorbidity.

Association Between Myasthenia Gravis and Memory: A Systematic Review and Meta-Analysis

Objective: The studies have produced contradictory results regarding the association between myasthenia gravis (MG) and cognitive function, especially for the cognitive domains of memory. This meta-analysis was dedicated to exploring the association between MG and memory, which was represented by the immediate recall and delayed recall.

Methods: Using the random effects models, this study analyzed memory in MG based on data from the studies retrieved from four electronic databases from inception to February 2021. Disease severity was graded according to the Myasthenia Gravis Foundation of America (MGFA) classification. We defined ocular myasthenia gravis (OMG) (MGFA Grade I) as Class I, mild, and moderate generalized myasthenia gravis (GMG) (MGFA Grade IIa, IIb, IIIa, and IIIb) as Class II.

Results: In total, eight studies of 274 patients and 211 healthy controls were included. The significant associations were found between MG and memory. Compared with the healthy control group, the patients with MG performed significantly worse in the terms of immediate recall [standardized mean difference (SMD) = −0.65, 95% CI = −0.97 to −0.33, P < 0.001, I² = 64.1%] and delayed recall (SMD = −0.49, 95% CI = −0.88 to −0.1, P < 0.05, I² = 76.3%). Compared with the patients with Class I MG, those with Class II MG did not have significantly different scores in immediate recall (SMD = −0.07, 95% CI = −0.35 to 0.21, P = 0.614, I² = 0%) and delayed recall (SMD = 0.63, 95% CI = −0.29 to 1.55, P = 0.178, I² = 87.9%).

Conclusion: The patients with MG showed lower memory performance, such as both immediate and delayed recall ability. There was no association between the severity of MG and memory. Future studies should address whether these associations are casual and modifiable.

Neuromuscular hyperexcitability syndromes

PURPOSE OF REVIEW

To provide an update on recent developments regarding acquired, antibody-mediated, neuromuscular hyperexcitability syndromes, including Isaac's and Morvan's syndromes, cramp-fasciculation syndrome and rippling muscle disease, and their genetic differential diagnoses.

RECENT FINDINGS

Antibodies in auto-immune peripheral nerve hyperexcitability syndromes (PNHS) are directed against CASPR2 and LGI1, proteins of the voltage-gated potassium channel (VGKC) complex. We discuss the significance of 'double-negative' VGKC antibodies in PNHS and the rationale for ceasing VGKC antibody testing (but testing CASPR2 and LGI1 antibodies instead) in clinical practice. Recent case reports also expand the possible clinical phenotypes related to CASPR2/LGI1 antibodies, but the interpretation of these findings is complicated by the frequent association of antibody-mediated neuromuscular hyperexcitability syndromes with other auto-immune disorders (e.g. myasthenia gravis).Finally, a hereditary origin of neuromuscular hyperexcitability should always be considered, even in non-VGKC-related genes, as evidenced by the recently discovered high frequency of HINT1 mutations in people of Slavic origin.

SUMMARY

This review provides an update on recent clinical, immunological and genetic developments in neuromuscular hyperexcitability syndromes. We also provide a guide for the clinician for diagnosing and managing these disorders in clinical practice, with a special focus on the main differential diagnoses.

Myasthenia Gravis-An Analysis of Multimodal Evoked Potentials

INTRODUCTION

The aim of this study is a comprehensive analysis of the parameters of exogenous evoked potentials (visual, brainstem auditory, and somatosensory) in patients with myasthenia gravis (MG), a prototype of both neuromuscular junction disease and autoimmune disease. The study also seeks to isolate electrophysiological changes that may indicate disorders within the central and/or peripheral nervous system.

METHODS

A total of forty-two consecutive patients with myasthenia gravis (24 women, 18 men) were included in the study. All of the patients underwent EP examination. MR images were also analyzed.

RESULTS

In the group of MG patients, the latency of P100 (113.9 ± 13.9; p < 0.0001) VEP, wave III (3.92 ± 0.29; p = 0.015), wave V (5.93 ± 0.32; <0.0001), interlatency III-V (2.00 ± 0.12; p < 0.0001), interlatency I-V (4.20 ± 0.28; p < 0.001) BAEP, and all components of SEP (N9, P10, N13, P16, N20, P22) were significantly longer. Mean wave I and V amplitude BAEP were relatively lower.

CONCLUSIONS

The results of the study suggest the presence of disturbances in the bioelectric activities of the central and peripheral nervous system in MG patients.

What's in the Neuromuscular Junction Literature?

Four retrospective studies from the United States, Europe, and Asia address outcomes in juvenile myasthenia gravis. Common features include earlier onset with ocular myasthenia gravis (MG) and generally good outcomes overall. Patients who were seronegative, had equivocal acetylcholine receptor (AChR) antibodies, or had only clustered AChR antibodies had better outcomes. An article highlighting the utility of median nerve slow-repetitive stimulation is reviewed and another showing the high sensitivity of repetitive nerve stimulation in myasthenic crisis is covered. Two articles address the thymus and thymectomy in non-AChR antibody-positive autoimmune MG. Longer term data on eculizumab as well as studies of cyclophosphamide, rituximab, and tacrolimus are summarized. Other topics include the possible role of statins in MG and central nervous system autoimmune comorbidities.

Thymic Involution and Altered Naive CD4 T Cell Homeostasis in Neuromyelitis Optica Spectrum Disorder

Circulating T helper cells with a type 17-polarized phenotype (TH17) and expansion of aquaporin-4 (AQP4)-specific T cells are frequently observed in patients with neuromyelitis optica spectrum disorder (NMOSD). However, naive T cell populations, which give rise to T helper cells, and the primary site of T cell maturation, namely the thymus, have not been studied in these patients. Here, we report the alterations of naive CD4 T cell homeostasis and the changes in thymic characteristics in NMOSD patients. Flow cytometry was performed to investigate the naive CD4⁺ T cell subpopulations in 44 NMOSD patients and 21 healthy controls (HC). On immunological evaluation, NMOSD patients exhibited increased counts of CD31^+thymic naive CD4⁺ T cells and CD31^-cental naive CD4⁺ T cells along with significantly higher fraction and absolute counts of peripheral blood CD45RA⁺ CD62L⁺ naive CD4⁺ T cells. Chest computed tomography (CT) images of 60 NMOSD patients and 65 HCs were retrospectively reviewed to characterize the thymus in NMOSD. Thymus gland of NMOSD patients exhibited unique morphological characteristics with respect to size, shape, and density. NMOSD patients showed exacerbated age-dependent thymus involution than HC, which showed a significant association with disease duration. These findings broaden our understanding of the immunological mechanisms that drive severe disease in NMOSD.

Myasthenia Gravis Masquerading as an Idiopathic Unilateral Facial Paralysis (Bell's Palsy)-A Very Rare and Unique Clinical Find

Myasthenia gravis (MG) is an uncommon autoimmune neuromuscular junction disorder manifesting as fluctuating weakness of skeletal muscles. To add to its repertoire of mimicking a wide range of neurological disorders, the present case report is, to the best of our knowledge, the very first to describe MG masquerading as an idiopathic unilateral facial paralysis (Bell's palsy, BP). Our case report is distinct, highlights a novel clinical occurrence, offers new insights of how different neurological disorders may overlap with each other, and reminds neurologists to have a very broad and thorough comprehension for effective diagnoses and treatment plans. Several other conditions that produce facial nerve palsy identical to BP have also been discussed.