Myasthenia gravis: changes observed in a 30-years retrospective clinical study of a hospital-based population

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Seropositivity for West Nile Virus Antibodies in Patients Affected by Myasthenia Gravis

BACKGROUND

Myasthenia gravis (MG) is an autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles. Specific auto-antibodies against acetylcholine receptor (AChR) are present in the majority of MG patients, although the main cause behind its development still remains unclear. Recently MG development following West Nile virus (WNV) infection has been described in patients without any earlier evidence of MG. It is known that infectious agents trigger immune response and occasionally initiate autoimmune disease. WNV, the causative agent of both benign illness and neuroinvasive disease, has become endemic in many countries in all continents.

METHODS

In the present study, 29 patients (15 males and 14 females, 19 - 78 years old) with confirmed diagnosis of MG and elevated levels of AChR autoantibodies were screened for the presence of serum anti-WNV antibodies and compared to a similar population affected by different autoimmune diseases. Indirect immunofluorescent antibody technique was used to evaluate the reaction of patients' sera on cells infected by WNV.

RESULTS

Positive fluorescent signals for anti-WNV IgG were obtained in 17% of MG patients, although no clinical manifestations related to WNV infection were reported. These results are in agreement with previous data and appear of great interest in the understanding of the pathogenic autoimmune mechanisms at the bases of MG development.

CONCLUSION

As already observed in other human autoimmune diseases, pathogen-triggered autoimmunity could be involved in MG by breaking immunological self-tolerance through possible mechanisms of molecular mimicry between virus proteins and AChR subunits. In predisposed individuals, WNV infection could also represent an additional risk factor to initiate MG.

Outcomes of Thymoma Treated with Multimodality Approach: A Tertiary Cancer Center Experience of 71 Patients

Aims

To explore the demographics and clinical outcome of patients with thymoma treated with a multimodality approach at our institute.

Methods

A total of 71 patients with thymoma (Masaoka stage II-IV and WHO subtype AB-B3) treated from 1999-2013 were included in this retrospective analysis. Age, stage, WHO subtypes, details of surgery, radiotherapy, and chemotherapy were noted. Progression-free survival (PFS) was estimated using Kaplan-Meier method and SPSS (version 21.0) was used for statistical analysis.

Results

Male:female ratio was 56:15 with median age at presentation of 41 years. Stage-wise distribution was 6:46:19 for stage II, stage III, and stage IV, respectively. A total of 31 patients (44%) had associated myasthenia gravis and 3 had pure red cell aplasia. A total of 57 patients (80%) underwent radical thymectomy and all of these patients received adjuvant radiotherapy. A total of 15 patients and 7 patients received adjuvant chemotherapy and neoadjuvant chemotherapy, respectively. At median follow-up of 19.3 months (range 7.9-72.3 months), 2-year and 3-year PFS rate for the entire cohort was 78.3% and 57.1%, respectively. On univariate analysis, surgery (hazard ratio [HR] 3.881; 95% confidence interval [CI] 1.784-19.220; p = 0.006) and stage (HR 5.457; 95% CI 1.567-18.996; p = 0.0001) were significant prognostic factors and association with myasthenia gravis (HR 0.404; 95% CI 0.151-1.078; p = 0.078) trended towards better PFS. Stage retained its prognostic significance (HR 5.501; 95% CI 2.076-14.573; p = 0.0006) on multivariate analysis.

Conclusions

Multimodality management of locally advanced thymoma yields decent survival outcomes. Masaoka stage is an independent prognostic factor for survival and radical surgery should be contemplated in all cases of locoregionally limited thymoma.

Incidence of thymoma in myasthenia gravis: a systematic review

Background and Purpose

Myasthenia gravis (MG) is usually comorbid with thymoma. More accurate estimates of the incidence thymoma in MG will help inform patients and their physicians, facilitate health policy discussions, provide etiologic clues, and optimize the management of MG.

Methods

We conducted a systematic review search of relevant English-language studies published between 1960 and 2012 using MEDLINE and Embase. We identified additional studies by reviewing the bibliographies of the retrieved articles and hand searched the main neurology journals. Only incidence studies and case series of unselected MG patients in which information about thymoma were included.

Results

Out of 2206 potentially relevant studies, 49 met the inclusion criteria. Although there was a considerable degree of heterogeneity, the pooled estimate of the incidence of thymoma in MG was 21% (95% confidence interval, 20-22%). The pooled incidence was significantly higher for surgery-based studies than for population- and hospital-based studies. A large proportion of the reported thymomas were noninvasive. Furthermore, thymoma appears to occur significantly more frequently among male MG patients and those older than 40 years at the onset of MG.

Conclusions

Thymoma is common in MG patients, but appears to be found more often in male MG patients and those older than 40 years at the onset of MG. Further research is needed to expand our understanding of these association conditions.

Autoimmune thyroid disease and other non-endocrine autoimmune diseases

Introduction, Autoimmune diseases are chronic conditions initiated by the loss of immunological tolerance to self-antigens. They constitute heterogeneous group of disorders, in which multiple alterations in the immune system result in a spectrum of syndromes that either target specific organs or affect the body systematically. Recent epidemiological studies have shown a possible shift of one autoimmune disease to another or the fact that more than one autoimmune disease may coexist in a single patient or in the same family. Numerous autoimmune diseases have been shown to coexist frequently with thyroid autoimmune diseases. Autoimmune thyroid disease and other organ specific non-endocrine autoimmune diseases. This part of the study reviews the prevalence of autoimmune thyroid disease coexisting with: pernicious anaemia, vitiligo, celiac disease, autoimmune liver disease, miastenia gravis, alopecia areata and sclerosis multiplex, and several recommendations for screening have been given. Autoimmune thyroid disease and other organ non-specific non-endocrine autoimmune diseases. Special attention is given to the correlation between autoimmune thyroid disease and rheumatoid arthritis, systemic lupus erythematosus, syndrome Sj?gren, systemic sclerosis and mixed connective tissue disease. Conclusions. Screening for autoimmune thyroid diseases should be recommended in everyday clinical practice, in patients with primary organ-specific or organ non-specific autoimmune disease. Other?wise, in patients with primary thyroid autoimmune disease, there is no good reason of seeking for all other autoimmune diseases, although these patients have a greater risk of developing other autoimmune disease. Economic aspects of medicine require further analyzing of these data, from cost/benefit point of view to justified either mandatory screening or medical practitioner judgment.

Frequency of autoimmune diseases in myasthenia gravis: a systematic review

The course of myasthenia gravis (MG) may get complicated by the development of other autoimmune diseases. Estimates of the frequency of autoimmune diseases will help inform patients and physicians, direct health policy discussion, provide etiologic clues, and optimize the management of MG. However, the frequency of autoimmune diseases in people with MG is still uncertain. A systematic search for English language studies was conducted by MEDLINE and EMBASE from 1960 through 2010. Incidence studies and case series of all MG subtypes with information about autoimmune diseases were included; 25 studies met the inclusion criteria. Although there was considerable heterogeneity, the pooled estimate of the coexisting autoimmune diseases in MG was 13% (95% confidence interval, 12%-14%). Autoimmune thyroid disease seems to occur more frequently than other autoimmune conditions in MG patients. Heterogeneity in study estimates could be explained by ascertainment bias and case mix. Furthermore, autoimmune diseases occurred significantly more often in females and anti-acetylcholine receptor seropositive MG patients. Patients with MG have an increased frequency of coexisting autoimmune diseases. Autoimmune diseases seem to occur more often in female and seropositive MG patients. Further research is needed to expand our understanding of these associations.

Ocular myasthenia gravis and Graves disease in a 10-year-old child

We report the association between myasthenia gravis and Graves disease in a 10-year-old boy and discuss the important aspects of both diseases, the importance of recognizing the association, and the investigations of choice to distinguish the 2 disorders. Early diagnosis of the 2 disorders may help in effective treatment institution with more rapid treatment responses with a possible improvement in prognosis and clinical course. Resolution of myasthenia gravis is not expected until the euthyroid state is restored. We recommend complete thyroid status review on all patients presenting with ocular myasthenia gravis.

Epidemiology of neuroimmunological diseases

This review gives an overview of various neuroimmunological diseases in terms of incidence and prevalence rates, age and sex distribution, and the frequency of subtypes, if applicable. The disorders selected for review are inflammatory muscle disorders (polymyositis, dermatomyositis and inclusion body myositis), myasthenia gravis, immune-mediated polyneuropathies (Guillain-Barré syndrome, chronic polyneuritis and vasculitic neuropathies), and multiple sclerosis.

High Prevalence of Systemic Lupus Erythematosus in 78 Myasthenia Gravis Patients: A Clinical and Serologic Study

OBJECTIVE

The objective of this study was to define the prevalence of systemic lupus erythematosus (SLE) in patients with myasthenia gravis (MG).

METHODS

Seventy-eight MG patients recruited unselectively from Israeli MG database were evaluated by medical history, physical examination and serology (ANA at 1:100 and anti-ds-DNA at 1:10 dilution) for the presence of SLE, which was defined by the presence of four or more American College of Rheumatology diagnostic criteria.

RESULTS

Thirty-one (40%) of our patients were males and 47 (60%) were females. Their mean age at time of the study was 51.5 +/- 14.5 years. Forty patients (51%) had an early-onset disease (<40 years); 90% had generalized and 10% had limited ophthalmic MG. Significant titers of ANA and ds-DNA autoantibodies were observed in 38.5% and 19.2% of the patients. In six (7.7%), a definitive diagnosis of SLE was established (MG was first diagnosed; there was no association with previous thymectomy), three of them revealed lupus-related neurologic manifestations. All six patients were females with an early onset generalized MG.

CONCLUSION

High prevalence of SLE and lupus-related autoantibodies exist in female MG patients. Thus, MG patients should be evaluated for the coexistence of SLE, and assessment for MG is suggested in lupus patients with unexplained muscular weakness.

Non-thyroid autoantibodies in autoimmune thyroid disease

Autoimmune thyroid disease is frequently accompanied by other organ-specific and non-organ-specific diseases, most likely because there is sharing of genetic and possibly environmental susceptibility factors. These associations are well recognized in the autoimmune polyglandular syndromes; autoimmune thyroid disease is one of the three major endocrinopathies in the type 2 syndrome and occurs in around 4% of type 1 patients. This review considers the frequency of disease-specific autoantibodies in patients with thyroid autoimmunity and briefly examines the role of such antibodies in performing screening for the associated conditions. Recommendations are made for using such autoantibody tests in the setting of patients with autoimmune thyroid disorders, and also for the utility of screening for thyroid autoimmunity in patients with pernicious anaemia, Addison's disease, coeliac disease, primary biliary cirrhosis, myasthenia gravis, lymphocytic hypophysitis, systemic lupus erythematosus and rheumatoid arthritis. At present, however, there are no large-scale trials that have shown the cost-benefit ratio of autoantibody screening for autoimmunity screening, and clinicians must use individual judgement combined with heightened awareness to identify who to test.