Myasthenia gravis: a long term follow-up study of Swedish patients with specific reference to thymic histology

Effect of thymectomy on the frequencies of peripheral regulatory B and T lymphocytes in patients with Myasthenia gravis-a pilot study

AIM

We aimed to investigate the relationship between the peripheral lymphocyte subset frequency and thymectomy in patients with myasthenia gravis (MG).

MATERIALS AND METHODS

The frequencies of regulatory B (Breg) and regulatory T (Treg) cells in peripheral blood samples obtained from 69 patients with MG and 10 healthy controls were analyzed using flow cytometry. Serum acetylcholine receptor antibodies (AchR-Ab) were measured. Patients with MG were subdivided into pre-thymectomy, post-thymectomy, and normal thymus control group.

RESULTS

The percentage of Breg cells was significantly decreased in both the pre-thymectomy (7.92 ± 1.30%) and post-thymectomy (8.14 ± 1.34%) groups compared to healthy controls (16.02 ± 2.78%) and reduced in the exacerbation and relapse phase compared to the stable maintenance stage. The proportion of cluster of differentiation (CD) 4 + CD25 + T cells and CD4 + CD25 + CD127low/- Treg cells in MG patients were not significantly different than healthy controls. AchR-Ab titers in aggravating or recurrence patients after thymectomy were significantly higher than that of the stable remission patients (11.13 ± 0.70 and 6.03 ± 0.85 nmol/L, respectively; p < 0.001).

CONCLUSION

The frequency of Breg cells may serve as a potential indicator of MG prognosis, while Treg cell frequency did not demonstrate the same prognostic ability. The concentration of AchR-Ab can be used as a dynamic monitoring index of disease severity in patients with MG.

The Duke Myasthenia Gravis Clinic Registry: II. Analysis of outcomes

INTRODUCTION/AIMS

The Duke Myasthenia Gravis (MG) Clinic Registry contains comprehensive physician-derived data on patients with MG seen in the Duke MG Clinic since 1980. The aim of this study was to report outcomes in patients seen in the clinic and treated according to the International Consensus Guidance statements.

METHODS

This is a retrospective cohort study of patients initially seen after 2000 and followed for at least 2 years in the clinic. Treatment goal (TG) was defined as achieving MGFA post-intervention status of "minimal manifestations" or better; PIS was determined by the treating neurologist. Time-to-event analysis, including Cox proportional hazards modeling, was performed to assess the effect of sex, acetylcholine receptor antibody (AChR-Ab) status, age at disease onset, distribution (ocular vs generalized), thymectomy, and thymoma on the time to achieve TG.

RESULTS

Among the 367 cohort patients, 72% achieved TG (median time less than 2 years). A greater proportion of patients with AChR-Abs and thymectomy achieved TG and they did so sooner than patients without these antibodies or thymectomy. Otherwise, there were no significant differences in these findings within the tested subgroups. The disease duration at the first Duke Clinic visit was shorter in patients who achieved TG than in those who did not.

DISCUSSION

These results demonstrate outcomes that can be achieved in patients with MG treated according to the current Consensus Guidance statements. Among other things, they can be used to determine the added value and potential role of new treatment modalities developed since 2018.

Comparison of Short-Term Post-Thymectomy Outcomes by Time-Weighted Dosages of Drug Requirements between Thymoma and Non-Thymoma Myasthenia Gravis Patients

(1) Background: Early thymectomy is suggested in all clinically indicated myasthenia gravis (MG) patients. However, short-term clinical response after thymectomy in MG patients has been limitedly described in the literature. This study aimed to compare the 5-year post-thymectomy outcomes between thymoma (Th) and non-thymoma (non-Th) MG patients. (2) Methods: MG patients aged ≥18 years who underwent transsternal thymectomy and had tissue histopathology reports in Songklanagarind Hospital between 2002 and 2020 were enrolled in a retrospective review. The differences in the baseline demographics and clinical characteristics between ThMG and non-Th MG patients were studied. We compared the time-weighted averages (TWAs) of daily required dosages of pyridostigmine, prednisolone or azathioprine to efficiently maintain daily living activities and earnings between the MG patient groups during 5 consecutive years following thymectomy. Post-thymectomy clinical status, exacerbations or crises were followed. Descriptive statistics were used for analysis with statistical significance set at p < 0.05. (3) Results: ThMG patients had significantly older ages of onset and shorter times from the MG diagnosis to thymectomy. Male gender was the only significant factor associated with ThMG. TWAs of the daily MG treatment drug dosages required showed no differences between the groups. Additionally, the rates of exacerbations and crises were not different, but decremental trends were shown in both groups after the thymectomies. (4) Conclusions: The daily dosage requirements of MG treatment drugs were not different. There was a trend of decreasing adverse event rates despite no statistically significant differences during the first 5 years after thymectomy in ThMG and non-ThMG patients.

Determinants of Suboptimal Outcome Following Thymectomy in Myasthenia Gravis

Background

Response to thymectomy in myasthenia gravis (MG) is influenced by various patient-, disease-, and therapy-related factors.

Methods

Retrospective analysis of 128 patients with MG who underwent maximal thymectomy over 15 years was done to identify the determinants of suboptimal clinical outcome.

Results

Among the 128 patients, 62 (48.4%) were females with a mean age of 38.97 (12.29) years. Thymomatous MG occurred in 66 (51.6%). Overall improvement from preoperative status was noted in 88 (68.8%) patients after mean follow-up of 51.68 (33.21) months. The presence of thymoma was the major predictor of suboptimal clinical outcome (P = 0.001), whereas age, gender, preoperative disease severity, and seropositive status did not attain significance. Patients with better outcome had received higher steroid dose preoperatively (P = 0.035).

Conclusions

Suboptimal response after thymectomy occurred in one-third of MG patients, more commonly with thymomatous MG. Relationship of preoperative steroid therapy to remission merits evaluation.

Prevalence and risk factors of myasthenia gravis recurrence post-thymectomy

Objectives:

To evaluate the prevalence and the factors associated with recurrence of myasthenia gravis following thymectomy.

Methods:

Six electronic databases which reported on recurrence of myasthenia gravis following thymectomy and/or its risk factors from 1985 to 2018 were searched. Summary prevalence and risk values obtained based on the random effect models were reported.

Results:

Seventy (70) papers containing 7,287 individuals with myasthenia gravis who received thymectomy as part of their management were retrieved. The patients had a mean follow-up of 4.65 years post-thymectomy. The prevalence of myasthenia gravis recurrence post-thymectomy was 18.0% (95% CI 14.7–22.0%; 1865/7287). Evident heterogeneity was observed (I²=93.6%; p<0.001). Recurrence rate was insignificantly higher in male compared with female patients (31.3 vs. 23.8%; p=0.104). Pooled recurrence rates for thymomatous (33.3%) was higher than the rate among non-thymomatous (20.8%) myasthenia gravis patients (Q=4.19, p=0.041). Risk factors for recurrence include older age, male sex, disease severity, having thymomatous myasthenia gravis, longer duration of the myasthenia gravis before surgery, and having an ectopic thymic tissue.

Conclusion:

A fifth of individuals with myasthenia gravis experience recurrence after thymectomy. Closer monitoring should be given to at-risk patients and further studies are needed to understand interventions to address these risks.

Clinical characteristics and outcomes of thymoma-associated myasthenia gravis

BACKGROUND AND PURPOSE

Prognosis of myasthenia gravis (MG) in patients with thymoma is not well established. Moreover, it is not clear whether thymoma recurrence or unresectable lesions entail a worse prognosis of MG.

METHODS

This multicenter study was based on data from a Spanish neurologist-driven MG registry. All patients were aged >18 years at onset and had anti-acetylcholine receptor antibodies. We compared the clinical data of thymomatous and nonthymomatous patients. Prognosis of patients with recurrent or nonresectable thymomas was assessed.

RESULTS

We included 964 patients from 15 hospitals; 148 (15.4%) had thymoma-associated MG. Median follow-up time was 4.6 years. At onset, thymoma-associated MG patients were younger (52.0 vs. 60.4 years, p < 0.001), had more generalized symptoms (odds ratio [OR]: 3.02, 95% confidence interval [CI]: 1.95-4.68, p < 0.001) and more severe clinical forms according to the Myasthenia Gravis Foundation of America (MGFA) scale (OR: 1.6, 95% CI: 1.15-2.21, p = 0.005). Disease severity based on MGFA postintervention status (MGFA-PIS) was higher in thymomatous patients at 1 year, 5 years, and the end of follow-up. Treatment refractoriness and mortality were also higher (OR: 2.28, 95% CI: 1.43-3.63, p = 0.001; hazard ratio: 2.46, 95% CI: 1.47-4.14, p = 0.001). Myasthenic symptoms worsened in 13 of 27 patients with recurrences, but differences in long-term severity were not significant. Fifteen thymomatous patients had nonresectable thymomas with worse MGFA-PIS and higher mortality at the end of follow-up.

CONCLUSIONS

Thymoma-associated MG patients had more severe myasthenic symptoms and worse prognosis. Thymoma recurrence was frequently associated with transient worsening of MG, but long-term prognosis did not differ from nonrecurrent thymoma. Patients with nonresectable thymoma tended to present severe forms of MG.

Incidence, mortality, and economic burden of myasthenia gravis in China: A nationwide population-based study

Background

Myasthenia gravis (MG) is the most common primary disorder of neuromuscular transmission, but the incidence of MG in China is unknown. We conducted the first nationwide study to determine the incidence and mortality rates of MG in all age groups at the national level in China.

Methods

This national population-based registry study is based on the database of the Hospital Quality Monitoring System of National Health Commission, which covers 1665 hospitals providing myasthenia gravis care in 31 provinces and municipalities across China. 94,638 hospital admissions for 59,243 myasthenia gravis patients were identified from January 1st, 2016 to December 31st, 2018. Myasthenia gravis was identified by ICD-10 codes (G70). Incidence of myasthenia gravis was stratified by age, sex, and province.

Findings

Of 59,243 patients, 30,503 individuals with myasthenia gravis were newly diagnosed. Age and sex adjusted incidence of myasthenia gravis was 0.68 per 100,000 person-years, with highest in the age group of 70–74 years. The incidence in females was 0.76 per 100,000 and 0.60 per 100,000 in males. The admission mortality rate was 14.69‰. Respiratory failure was the leading cause of death in patients with myasthenic crisis. There were 14,840 patients with thymomas, encompassing 14,636 (26.5%) adults and 204 (7.1%) juveniles. 9453 (63.7%) patients with thymomas underwent thymomectomy. The median length of hospital stay was 8 days (interquartile range (IQR) 4 to 15 days) with median hospitalization cost $1037 (IQR $493 to $2925). The Basic Medical Insurance was the most common payment method, covering 67.4% of patients.

Interpretation

The age and sex adjusted incidence of MG was 0.68 per 100,000 person-years in China. The admission mortality rate was 14.69‰. Most cases of new onset MG occurred in the seventh decade of life.

Funding

National Science Foundation of China (91642205, and 81830038); Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing

Altered naive CD4+ T cell homeostasis in myasthenia gravis and thymoma patients

In Myasthenia Gravis (MG) thymic pathologies are often present and thymectomy is used as treatment. By flow cytometry we elucidated alterations of naïve CD4⁺ T cell homeostasis in MG patients and patients with thymoma. MG patients showed increased absolute numbers of CD31^{- central}naïve CD4⁺ T cells. Thymoma patients displayed a significantly higher fraction of peripheral blood CD31^{+ thymic}naive T cells. We show an altered naive CD4⁺ T cell homeostasis in MG patients that might predispose to autoimmunity. Aberrant generation of T cells in thymoma can be detected by an increased frequency of CD31^{+ thymic}naive CD4⁺ T cells in the periphery.

G, Cataneo DC. Thymectomy in nonthymomatous myasthenia gravis - systematic review and meta-analysis

BACKGROUND

The objective of this study is to evaluate by means of a systematic review, the efficacy of thymectomy as compared to medical treatment for non-thymomatous myasthenia gravis (MG).

METHODS

Medline, Embase, and Lilacs were searched for experimental and observational studies that compared non-surgical (drug therapy) and surgical treatment of non-thymomatous MG (thymectomy performed by the transsternal approach). Inclusion criteria were: studies that compared the two types of treatment and had at least 10 adult patients in each group. Exclusion criteria were articles published before 1970, as well as those that included patients treated before 1950. The outcomes evaluated were: remission, and improvement rates. RevMan 5.3 software provided by the Cochrane Collaboration was used. When the heterogeneity between the studies was greater than 75%, a meta-analysis was not performed according to RevMan guidelines.

RESULTS

The total number of patients evaluated in 19 articles selected was 5841 (2911 surgical and 2930 non-surgical). Two included randomized clinical trials showed superiority of the surgical treatment over the non-surgical. Four retrospective studies with 379 patients paired by gender, age, and other confounders, also showed superiority of surgical treatment (OR 4.10, 95% CI 2.25 to 7.44; I2 = 20%). In meta-analyses, remission assessed in 17 studies (5686 patients) was greater in patients who underwent surgical treatment (OR 2.34, 95% CI 1.79 to 3.05; I2 = 56%). For improvement assessed in 13 studies (3063 patients) were not appropriate to carry out the meta-analysis due to the high heterogeneity among the studies in the outcome (87%).

CONCLUSION

Thymectomy may be considered effective in the treatment for non-thymomatous MG, with remission rate higher than for non-surgical treatment.

Thymectomy for Myasthenia Gravis: A 10-year Review of Cases at the Hospital Universiti Sains Malaysia

BACKGROUND

A thymectomy is considered effective for patients with myasthenia gravis (MG). Although a few studies have described the role of a thymectomy in the treatment of MG in Asians countries, there are no published data on the application of this surgical approach for MG in Malaysia. We aimed to describe the clinical outcomes of MG patients who underwent a thymectomy and the factors affecting these outcomes.

METHODS

This was a retrospective study involving 16 patients with MG who underwent a thymectomy at the Hospital Universiti Sains Malaysia (HUSM) from January 2002 until December 2012, with a follow-up period ranging from 3-120 months.

RESULTS

The study consisted of 16 patients aged 22-78 years, 10 of whom were males. The overall remission/improvement rate was 87.5%, and the rate of clinical outcomes classified as unchanged/worsened was 12.5%. Thymomamatous or non-thymomamatous MG, histology features, Osserman stage and the duration of follow-up were not significant prognostic factors. Post-operative mortality was 6.2% (1 of 16 patients died of septic shock).

CONCLUSION

A thymectomy seems to be an effective treatment for MG, with low surgical morbidity. Patients with a lower Osserman stage and those with/without thymomas had favourable outcomes.

Clinical features of patients with Myasthenia gravis from the Henan province, China

INTRODUCTION

Myasthenia gravis (MG) occurs globally, and many studies have indicated that there are regional differences in epidemiology, biomarkers, and prognosis of MG.

METHODS

A total of 478 patients with MG who visited hospitals in the Henan Province between January 2010 and February 2014 were included. Age, gender, age at onset, serum antibody, thymus pathology, treatment information, and Myasthenia Gravis Foundation of America (MGFA) classification were assessed.

RESULTS

Compared with previous reports from other areas, we found some differences in MG patients from Henan. The proportion of childhood MG in our study was lower than other reports of Oriental patients with MG. There seems to be an association between onset age, muscle involvement, and acetylcholine receptor antibody levels. Thymectomy improved the symptoms in 78.5% of thymectomy-treated patients.

CONCLUSIONS

These differences are likely related to geographical, environmental, and ethnic differences. Understanding these differences will help us to define more specific treatment.

The autoimmune spectrum of myasthenia gravis: a Swedish population-based study

OBJECTIVES

To determine the prevalence of myasthenia gravis (MG) and the rate of concurrent autoimmune diseases in patients with MG.

DESIGN AND SETTING

Using the Swedish health and population registers, during the period 2005-2010, we conducted a nested case-control study of patients with MG (n = 2045) with five age- and sex-matched population-based controls per case. Register-based MG diagnosis was validated against the Stockholm MG Cohort. Similar nested case-control studies were conducted in patients with multiple sclerosis (MS), as a neuroinflammatory disease control, and siblings of patients with MG.

MAIN OUTCOME MEASURE

Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated as a measure of the association between MG and other autoimmune diseases.

RESULTS

The prevalence of MG was 24.8/100,000, and patients with MG had an increased risk of another autoimmune disease compared to controls (22.0% vs. 8.9%; OR: 2.82, 95% CI: 2.49-3.20); this risk was stronger amongst younger persons and women. Polymyositis/dermatomyositis, systemic lupus erythematosus and Addison's disease, three conditions regulated by the HLA-B8-DR3 haplotype, were most strongly associated with MG, especially early-onset disease. HLA typing in the Stockholm MG Cohort showed that early-onset MG was indeed dominated by HLA-B8-DR3. The risk of another autoimmune disease was increased in both patients with MS and siblings of patients with MG, compared to their respective controls, but to a lesser extent than in patients with MG.

CONCLUSIONS

Our results suggest that MG shares risk factors with other autoimmune diseases, to a greater degree than MS, with a particular role of the HLA-B8-DR3 haplotype, especially amongst younger and female patients.

Eight-year follow-up of patients with myasthenia gravis after thymectomy

PURPOSE

To depict the long-term outcome of patients with myasthenia gravis after thymectomy in combination with immunotherapy, and the factors that may potentially affect the outcome.

METHODS

The 306 patients with myasthenia gravis who underwent extended thymectomy from January 1984 to December 2011 at Tongji Hospital were retrospectively evaluated.

RESULTS

The patients consisted of 174 cases with thymoma and 132 cases without thymoma. Pharmaceutical treatment was tailored for each case during follow-up. Nine patients with thymomatous myasthenia gravis died during the perioperative period, and 297 patients were followed for 8.6 years. By their latest visits, 241 patients (81.1%) gained satisfactory efficacy, 24 cases died (8.1%), and 32 cases (10.8%) remained unchanged or deteriorated. Favorable factors for satisfactory efficacy included the presence of ocular myasthenia gravis before operation, no presence of thymoma, and lack of concomitant diseases. It is interesting to mention that, patients with non-thymomatous myasthenia gravis obtained significantly higher rates of complete stable remission and clinical remission than the patients with thymomatous myasthenia gravis.

CONCLUSIONS

Extended thymectomy combined with immunotherapy is a preferred treatment with a satisfactory long-term remission rate. Patients with non-thymomatous myasthenia gravis have a much more promising prognosis than the patients with thymomatous myasthenia gravis. However, appropriate caution must be taken to discontinue pharmaceutical therapy as relapse remains a major concern after a patient who has already undergone thymectomy becomes symptom-free.

Repeated acetylcholine receptor antibody-concentrations and association to clinical myasthenia gravis development

INTRODUCTION

We aimed to examine the longitudinal association between Myasthenia Gravis (MG) clinical severity and concentration of acetylcholine receptor (AChR)-antibodies to evaluate if AChR-antibody variations correlate to disease severity. A positive AChR-antibody test is specific for MG.

MATERIAL AND METHODS

All patients from western Norway who had two or more AChR- antibody tests in the period 1983-2013 were identified. The Myasthenia Gravis Foundation of America (MGFA) Clinical Classification was used to grade disease development. Multiple ordinal logistic regression analysis was used to estimate a possible predictive effect for AChR-antibody concentration on MGFA classification result.

RESULTS

In 67 patients two or more AChR-antibody tests with a corresponding MGFA-score were performed, with a total of 309 tests. 56 patients were treated with immunosuppressive drugs and 11 by pyridostigmine only. There was a positive association between concentration of AChR-antibodies and longitudinal MGFA-score for the subgroup with immunosuppressive treatment, but not for those treated with pyridostigmine only. This association between AChR-antibody concentration and MGFA score declined with increasing time since onset (p = 0.005 for the interaction of group×time×concentration).

CONCLUSIONS

For MG patients with immunosuppressive treatment, repeated AChR-antibody measurements give information about clinical development, and can therefore be of support in therapeutic decisions.

Thymus pathology observed in the MGTX trial

The MGTX trial is the first prospective, randomized clinical trial that aims to evaluate the impact of extended transsternal thymectomy on myasthenic symptoms, prednisone requirements, and quality of life in patients with nonthymomatous, anti-acetylcholine receptor autoantibody-positive myasthenia gravis (MG). Here, we give an overview of the rationale of thymectomy and the standardized macroscopic and histopathological work-up of thymectomy specimens as fixed in MGTX standard operating procedures, including the grading of thymic lymphofollicular hyperplasia and the morphometric strategy to assess thymic involution.

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.

The predictive value of the presence of different antibodies and thymus pathology to the clinical outcome in patients with generalized myasthenia gravis

OBJECTIVES

To analyze the predictive value of anti-acetylcholine receptor antibodies (anti-AChR Ab) and anti-muscle specific kinase antibodies (anti-MuSK Ab), as well as the thymus pathology to the clinical outcome in patients with generalized myasthenia gravis (MG).

METHODS

We analyzed 138 patients with generalized MG, who were thymectomized and assayed for anti-AChR Ab and anti-MuSK Ab.

RESULTS

Anti-AChR Ab were detected in 84% of patients, while anti-MuSK Ab were present in 36% of the AChR Ab negative patients. Severe forms of the disease were more frequent in MuSK Ab positive, compared to the AChR Ab positive and complete seronegative patients. Thymic lymphoid follicular hyperplasia (LFH) was present in 60%, thymoma in 23%, atrophic thymus in 9% and the normal thymus in 8% of patients. LFH was more frequent among women, while thymoma and atrophic thymus were more frequent in men. The younger patients mainly had LFH and normal thymus, while thymoma and atrophic thymus were more frequent in older patients. The mildest clinical presentation was present in patients with normal thymus, while severe forms of the disease were registered in the patients with thymoma. The AChR Ab positive patients had more often LFH and thymoma, while within MuSK Ab positive patients atrophic thymus was most common.

CONCLUSION

The best disease outcome was observed in patients with normal thymus or LFH with anti-AChR Ab or without both types of antibodies.

A national epidemiological study of Myasthenia Gravis in Australia

BACKGROUND AND PURPOSE

Existing epidemiological studies of Myasthenia Gravis have generally examined small populations. Few national studies have been conducted, and published incidence and prevalence rates vary widely. We report one of the largest national studies of Myasthenia Gravis, and the first incidence and prevalence rates for Australia.

METHODS

Prescriptions for Pyridostigmine Bromide in 2009 were utilized from a national prescribing database to estimate incidence and the prevalence of symptomatic and treated disease. Crude rates were age-standardized to the WHO world population. We compared standardized rates to recent national studies from Norway and Taiwan.

RESULTS

In 2009, there were 2574 prevalent cases of symptomatic and treated Myasthenia Gravis, corresponding to an annual crude prevalence rate of 117.1 per 1 million residents. There were 545 incident cases, yielding a crude incidence rate of 24.9 per 1 million residents. The crude incidence in women and men was estimated to be 27.9 and 21.9 per 1 million, respectively. Prevalence and incidence rates were higher in women than men between the ages of 15 and 64 years, and were higher in men than women in those older than 65 years. Rates peaked between the ages of 74 and 84 years, declining thereafter. Standardized incidence was higher in Australia than Norway, but similar to Taiwan (P-values = 0.007 and 1.00, respectively).

CONCLUSIONS

This first Australian epidemiological study of symptomatic Myasthenia Gravis is one of the largest population-based studies ever reported and supports higher incidence rates for Myasthenia Gravis. Myasthenia Gravis disproportionately affected younger females and older males.

The association of systemic lupus erythematosus and myasthenia gravis: a series of 17 cases, with a special focus on hydroxychloroquine use and a review of the literature

The coexistence of systemic lupus erythematosus (SLE) and myasthenia gravis (MG) is rarely reported, and most of the published studies are case reports. Hydroxychloroquine, an antimalarial agent, is an essential treatment in patients with SLE but special caution is recommended when used in MG patients. We retrospectively analyzed the clinical features, laboratory findings, and outcome of 17 patients with both diseases with a special focus regarding hydroxychloroquine use and with a review of the literature. All patients were women. The mean age at MG onset and SLE diagnosis was 34.5 [14-64] and 37.8 [18-72] years, respectively. The presenting symptoms of MG were limb weakness (94%), ocular (88%) and bulbar involvement (53%). Autoantibodies against the acetylcholine receptor were positive in 94% of cases. The main manifestations of SLE included arthritis (88%), cytopenias (53%) and skin rash (41%). Treatment of SLE required hydroxychloroquine (94%), steroids (47%) and immunosuppressive drugs (18%). Among eight patients (47%) who developed MG after initiation of hydroxychloroquine, the question of induction of MG by hydroxychloroquine was raised in one patient. On the other hand, an exacerbation of myasthenic symptoms was only seen in one of the eight patients who received hydroxychloroquine after the diagnosis of MG. Including our cases, we reviewed a total of 70 patients with SLE and MG. Compared with a large series of 1,000 unselected SLE patients, those with associated MG were older, had lower incidence of cutaneous, renal, and neurological manifestations, and higher frequency of anticardiolipin antibodies and lupus anticoagulant. In conclusion, the clinical pattern of patients with SLE and MG seems to be characterized by a less severe course of SLE and higher frequency of antiphospholipid antibodies. Hydroxychloroquine treatment appears to be safe in this setting.

Autoimmune disease and subsequent digestive tract cancer by histology

BACKGROUND

Dysregulation of the immune function in autoimmune diseases could potentially lead to cancer development and there is definite evidence linking some autoimmune mechanisms with cancer. We analyzed systematically the occurrence of histology-specific digestive tract cancers in patients diagnosed with 33 different autoimmune diseases in order to address the question of shared susceptibility.

PATIENTS AND METHODS

Standardized incidence ratios (SIRs) were calculated for subsequent digestive tract cancers up to the year 2008 and in patients hospitalized for autoimmune disease after the year 1964.

RESULTS

Myasthenia gravis associated with five different cancers with SIRs ranging from 1.35 to 2.78. Pernicious anemia, Crohn disease, ulcerative colitis, systemic lupus erythematosis and psoriasis were also associated with cancers at multiple sites. Rheumatoid arthritis associated with no cancer and the standardized incidence ratio was decreased for colon adenocarcinoma, also in ankylosing spondylitis patients.

CONCLUSIONS

Increased risks of cancer were observed in patients with several autoimmune diseases. Myasthenia gravis and pernicious anemia were associated with many cancers; this is possibly related to immunosuppressant medication in myasthenia gravis. The decreased risks in colon and rectal adenocarcinomas in rheumatoid arthritis and ankylosing spondylitis suggest underlying inflammatory mechanisms as the risks may have been suppressed by the use of anti-inflammatory medication.

Management of myasthenic patients with thymoma

Myasthenia gravis (MG) associated with thymomas differs from nonthymomatous MG, and thymomas associated with MG are also different from non-MG thymomas. According to the World Health Organization classification, the incidence of MG in thymomas was the highest in the subtypes B2, B1, and AB. Transsternal approach is still regarded as the gold standard for surgical treatment of thymomas. Less-invasive techniques of thymectomy are promising, but it is too early to estimate their real oncological value. In the series including more than 100 patients, the prognosis for survival is better in patients with thymomas associated with MG than in those with non-MG thymomas, and the prognosis for patients with MG associated with thymoma is worse than that for patients with nonthymomatous MG.

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.

Myasthenia gravis in Ceará, Brazil: clinical and epidemiological aspects

A retrospective chart review was performed on patients diagnosed as having myasthenia gravis in Ceará State, Brazil and who were followed from October 1981 to June 2009. Clinical and epidemiologic aspects were evaluated. In this work, 122 patients were studied, of whom 85 (69.7%) were females and 37 (30.3%) were males. The disease duration ranged from five months to 50 years (8.9±8.1 years). Age at the first symptoms varied from 0 to 74 years (31.9±14.4 years). The first main symptoms and signs were ptosis, diplopia and limb weakness. Generalized myasthenia was the most common clinical presentation, but 5.1% (n=6) persisted as ocular myasthenia. Thymectomy was performed in 42.6% (n=52) of myasthenic patients. A thymoma was present in 10 patients. Serum acetylcholine receptor (AChR) antibodies were present in 80% (n=20) of specimens tested. The data presented are similar to those of studies performed in other countries.

Mapping of multiple susceptibility variants within the MHC region for 7 immune-mediated diseases

The human MHC represents the strongest susceptibility locus for autoimmune diseases. However, the identification of the true predisposing gene(s) has been handicapped by the strong linkage disequilibrium across the region. Furthermore, most studies to date have been limited to the examination of a subset of the HLA and non-HLA genes with a marker density and sample size insufficient for mapping all independent association signals. We genotyped a panel of 1,472 SNPs to capture the common genomic variation across the 3.44 megabase (Mb) classic MHC region in 10,576 DNA samples derived from patients with systemic lupus erythematosus, Crohn's disease, ulcerative colitis, rheumatoid arthritis, myasthenia gravis, selective IgA deficiency, multiple sclerosis, and appropriate control samples. We identified the primary association signals for each disease and performed conditional regression to identify independent secondary signals. The data demonstrate that MHC associations with autoimmune diseases result from complex, multilocus effects that span the entire region.

Response to therapy in myasthenia gravis with anti-MuSK antibodies

Myasthenia gravis (MG) with antibodies against the muscle-specific tyrosine kinase (MuSK abs) is often a severe disease requiring aggressive treatment. Various immunosuppressive (IS) regimens have been employed; the efficacy of plasma exchange is unanimously recognized, while the indication for thymectomy is controversial. We evaluated the response to therapy in 57 MuSK-positive patients (12 M/45 F) comparing our experience with other authors' results. Disease severity and response to treatment were graded according to MG Foundation of America; follow-up ranged from 0.5-29 years. Owing to both MG severity and the unsatisfactory response to cholinesterase inhibitors, most patients (54/57) needed IS treatment, and 35 received one or more courses of plasma exchange and intravenous immunoglobulin. At the end of follow-up, the rate of complete remission was 8.8%, and IS treatment had been withdrawn in only 10/54 patients. The extent of therapeutic response varied considerably. With conventional IS therapy (prednisone alone or in combination with azathioprine or cyclosporine), most patients achieved good control of their disease, but 30% of them were left with permanent facial and bulbar weakness. In patients with refractory disease, the use of mycophenolate mofetil and rituximab proved very effective, as also reported by other authors. In our and others' experience, MuSK-positive MG markedly improves with IS therapy, although, in comparison with the AChR-positive disease, it is characterized by a lower remission rate, as a higher proportion of patients remain dependent on treatment. Thymectomy is mostly considered scarcely effective; however, at present, no firm conclusions can be drawn on its role in the treatment of this form of MG.