Ocular presentation of myasthenia gravis: A natural history cohort

Clinical Characteristics and Outcomes of Generalized Myasthenia Gravis in Malaysia: A Single-Center Experience

BACKGROUND AND PURPOSE

Myasthenia gravis (MG) is clinically heterogeneous and can be classified into subgroups according to the clinical presentation, antibody status, age at onset, and thymic abnormalities. This study aimed to determine the clinical characteristics and outcomes of generalized MG (GMG) patients based on these subgroups.

METHODS

Medical records of MG patients from 1976 to 2023 were reviewed retrospectively. Patients with pure ocular MG were excluded. Data on demographic, clinical characteristics, laboratory features, and outcomes were analyzed.

RESULTS

This study included 120 GMG patients. There was a slight preponderance of female patients over male patients (male:female ratio=1:1.3), with the age at onset exhibiting a bimodal distribution. Female patients peaked at a lower age (21-30 years) whereas male patients peaked at a higher age (61-70 years). Most (92%, 105 of 114) patients had positive anti-acetylcholine receptor antibodies. Five patients were also tested for anti-muscle-specific tyrosine kinase antibodies, with two showing positivity. Thymectomy was performed in 62 (52%) patients, of which 30 had thymoma, 16 had thymic hyperplasia, 7 had an involuted thymus, and 6 had a normal thymus. There were significantly more female patients (68% vs. 45%, p=0.011) with early-onset disease (<50 years old) and thymic hyperplasia (33% vs. 0%, p<0.025). Most (71%) of the patients had a good outcome based on the Myasthenia Gravis Foundation of America postintervention status. GMG patients with early-onset disease had a significantly better outcome than patients with a late onset in univariate (58% vs. 37%, p=0.041) and multivariate (odds ratio=4.68, 95% confidence interval=1.17-18.64, p=0.029) analyses.

CONCLUSIONS

Female patients with early-onset MG and thymic hyperplasia had significantly better outcomes, but only early-onset disease was independently associated with a good outcome. These findings are comparable with those of other studies.

Investigation of the differential susceptibility of extraocular muscles in patients diagnosed with ocular myasthenia gravis based on the computerized diplopia test and the Ocular Motor Nerve Palsy Scale

Introduction

The pattern of extraocular muscle involvement in ocular myasthenia gravis varies across different reports, diverging from our own observations. Thus, we employed two novel tools to discern this pattern.

Methods

A retrospective analysis was conducted to collect and organize clinical data from 43 patients diagnosed with ocular myasthenia gravis. Each patient underwent both the computerized diplopia test and the Ocular Motor Nerve Palsy Scale assessment to evaluate the involvement of extraocular muscles.

Results

Among the patients, there were 30 male and 13 female individuals, with a total of 113 affected extraocular muscles identified. Among all the affected extraocular muscles, the involvement of the levator palpebrae superioris muscle accounted for 35.40%, medial rectus muscle 7.7%, lateral rectus muscle 16.81%, superior rectus muscle 13.27%, inferior rectus muscle 12.39%, superior oblique muscle 1.77%, and inferior oblique muscle 2.65% of the total affected extraocular muscles. The positivity rates of the Neostigmine test were 89.19%, AChR antibody detection was 59.38%, and repetitive nerve stimulation was 34.38%. The AChR antibody positive rate among patients with only diplopia was 100%; among those with only ptosis, it was 80%; and among those with both diplopia and ptosis, it was 86.67%.

Conclusion

The involvement of the extraocular muscles is not uniform. The levator palpebrae superioris exhibits the highest incidence rate, followed by the four rectus muscles and two oblique muscles. The inferior oblique involvement typically occurs when four or more EOMs are affected. Moreover, the levator palpebrae superioris and medial rectus show a higher tendency for bilateral involvement compared with other extraocular muscles.

The Role of Thymoma and Thymic Hyperplasia as Prognostic Risk Factors for Secondary Generalisation in Adults with Ocular Myasthenia Gravis: A Systematic Narrative Review

Purpose

The conversion of ocular myasthenia gravis (OMG) to generalised myasthenia gravis (GMG) is reported to differ depending on the presence of generalisation risk factors (Mazzoli et al. 2018). Thymic pathology has been recognised as a potential risk factor for generalisation in the literature (Teo et al. 2017). Thymoma and thymic hyperplasia have yet to be examined as a risk factor for generalisation of OMG independently of other risk factors in the literature. Thus, the purpose of this review is to examine the literature to identify whether thymoma and thymic hyperplasia do increase the risk of OMG progressing to GMG.

Methods

A literature search was carried out which employed a systematic approach. The search was undertaken using the following academic libraries: MEDLINE, Embase and Starplus. The search was limited to publications between the years 2001 to 2021. The search yielded 82 studies, which after the screening of titles and abstracts, left 62 studies for further analysis against the inclusion and exclusion criteria.

Results

The review found thymoma to be associated with an increased risk of GMG development. However, there was a scarce amount of literature which investigated thymic hyperplasia. Therefore, a firm conclusion could not be made with regards to thymic hyperplasia and the risk of GMG development.

Conclusions

This review provides evidence for the consideration of thymectomy early after thymomatous OMG diagnosis to prevent GMG conversion. As the review did not collect enough evidence to support the influence of thymic hyperplasia on OMG conversion, further research is required.

Clinical Characteristics Associated With Secondary Generalization in Patients With Ocular Myasthenia Gravis: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Ocular myasthenia gravis (OMG) is an autoimmune disorder resulting in ocular symptoms such as diplopia and ptosis. The proportion of patients who convert to secondary generalized myasthenia gravis (SGMG) reported in the literature has been varied. The aim of this systematic review was to determine the clinical characteristics of patients with OMG and the proportion of SGMG conversion.

METHODS

We conducted an electronic database search for randomized controlled trials, prospective nonrandomized studies, observational studies, and retrospective studies in EMBASE, CENTRAL, MEDLINE, and Web of Science. We included studies with patients with OMG who initially presented with ocular symptoms and signs only and were seen in clinical practice, reporting on the characteristics and outcomes of SGMG. We excluded studies with pediatric and congenital myasthenia gravis populations. Eligible studies included articles written in any language and containing data on patients with OMG. The main outcome measured was the proportion of patients with OMG who converted to SGMG and risk factors associated with secondary generalization of OMG. Two independent reviewers screened titles and abstracts and extracted data from full texts, reporting findings according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The methodology was evaluated using the Joanna Briggs Institute critical appraisal forms. PROSPERO registration number: CRD2021285257.

RESULTS

Thirty-one studies were included in the quantitative and qualitative analysis. The proportion of generalization ranged from 11% to 84%. The pooled proportion was 39% (95% CI 32%-47%, I 2 = 95.86%, p < 0.001 unweighted, low certainty). The pooled risk ratio of female sex for conversion to SGMG was 1.06 (95% CI 0.96-1.17, I 2 = 0% p = 0.614, 21 studies included, very low certainty), and the pooled risk ratio of acetylcholine receptor (AChR) positivity was 1.30 (95% CI 1.05-1.56, I 2 = 0% p = 0.455, 16 studies included, very low certainty).

DISCUSSION

Risk factors such as female sex and anti-AChR positivity have been identified to have possible associations with SGMG, but there are not enough quality observational studies. There is a need for a prospective global database of patients with OMG, including all countries with different populations.

Prognostic predictors of remission in ocular myasthenia gravis

BACKGROUND

Ocular myasthenia gravis (OMG) constitutes 15% of all myasthenia gravis patients.

METHODS

One hundred eight patients with OMG followed-up for over 36 months were retrospectively evaluated regarding factors associated with remission. Demographic features, neuro-ophthalmologic findings at onset, acetylcholine receptor (AChR Ab) and muscle-specifc tyrosine kinase antibodies (MuSK Ab), thymic status, single fiber electromyography (SFEMG) results were the variables considered.

RESULTS

Median age of disease onset was 57 years (range 18-82 years). Clinical features at onset was isolated ptosis in 55 (50.9%) and isolated diplopia in 33 (30.6%) patients. Combined ptosis and diplopia were present in 20 (18.5%) patients. Among 75 patients with ptosis, it was unilateral in 65 (86.7%) and bilateral in 10 (13.3%). AChR Abs were found in 66 (61.1%) and MuSK Abs in 2 (1.9%) patients. SFEMG abnormality was detected in 74 (68.5%) patients. Thymoma was present in 16 (14.8%) and thymic hyperplasia in 6 (5.6%) patients. Forty-one patients (37.9%) had been treated with pyridostigmine alone. Sixty-seven (62%) patients were given immunosupressive drugs. In 53 (49.1%) prednisone was used and in 14 (12.9%) patients it was combined with azathioprine. Thymectomy was performed in all 16 patients with thymoma. Complete stable remission (CSR) was achieved in 49 (45.4%) patients. Fifty-nine (54.6%) patients had reached minimal manifestation (MM) status; 32 (29.6%) having a status of MM-1 and 27 (25%) a status of MM-3.

CONCLUSIONS

The presence of AchR Abs (p = 0.034) and an abnormal SFEMG (p = 0.006) at onset as increased risk factors for the presence of ongoing signs necessitating medical treatment.

Dynamic nomogram for predicting generalized conversion in adult-onset ocular myasthenia gravis

PURPOSE

To explore the factors and risk mapping model of progression from ocular myasthenia gravis (OMG) to generalized myasthenia gravis (GMG) in adult-onset patients.

METHODS

A retrospective, observational cohort study was performed for 435 OMG patients with onset age older than 14 years old. Multivariate Cox regression was used to identify the independent factors affecting generalized conversions that then were incorporated into the construction of the nomogram.

RESULTS

Two hundred thirty-seven patients (54.5%) had transformed into GMG after a median of 1.1 years (range 0.1--9.1 years). The 6-, 12-, and 24-month generalized conversion rates were 31.7%, 49.8%, and 65.4%, respectively. Multivariable analysis showed that the early-onset age, male sex, concomitant autoimmune diseases (AID), positive results of anti-acetylcholine receptor antibodies, repetitive nerve stimulation abnormalities, the presence of thymoma, and prednisone treatment were significantly associated with the generalized conversions (hazard ratio [HR] = 0.598, 0.686, 1.554, 1.541, 2.020, 2.510, and 0.556, respectively). A nomogram was established to predict the possibility of generalization-free survival (GFS) in adult-onset OMG patients, and the model demonstrated good predictive performance with a C-index of 0.736 (95% confidence interval 0.703 ~ 0.769). Moreover, subgroup analyses were performed based on the presence or absence of prednisone therapy, and the results indicated that prednisone therapy has better prevention of generalized conversions in male, non-thymoma patients, and patients without other AID.

CONCLUSION

A new predictive nomograph and web-based survival calculator we developed show favorable applicability and accuracy in predicting long-term GFS in adult-onset OMG patients.

Generalization of ocular myasthenia gravis 10 years after onset

BACKGROUND

Generalization of ocular myasthenia gravis (OMG) represents a pejorative evolution, and no validated generalization-prevention strategy exists. The study aimed to determine the percentage of patients with OMG generalization and identify factors predictive of it to establish a prediction score.

METHODS

This retrospective, observational study included 151 patients diagnosed with OMG after an initial work-up in our institution. The outcome measure was time to MG generalization. The explanatory variables were age at onset (> 55 years), sex, first-year anti-acetylcholine-receptor antibody-positivity, repetitive nerve stimulation showing electromyogram decrement and corticosteroid use. Kaplan-Meier estimations of the probability of risk of generalization, and descriptive and multivariate Cox model analyses were computed. A nomogram combining explanatory variables was used to establish a score to predict the probability of OMG generalization.

RESULTS

Among 183 patients' charts identified, 151 had confirmed OMG. Their median follow-up was 5.7 years. Estimations (95% CI) of OMG-generalization risk at 1, 3 and 10 years post-symptom onset, respectively, were: 13.0% (7.3-18.2), 25.1% (17.5-32.0) and 37.8% (27.2-45.2). The p-value-based multivariate analysis associated generalization with female sex, electromyogram decrement and first-year anti-acetylcholine-receptor antibody positivity, and Akaike information criterion-based analysis retained those three parameters and corticosteroid use. A nomogram was built and validated with an optimism-corrected C-statistic of 0.68, and calibration plots showed good fit.

CONCLUSIONS

Our population's percentage of OMG generalization is in line with recent publications. Using the identified prognostic factors, the nomogram provided a score to predict the probable risk of generalization in our cohort.

Prediction of the generalization of myasthenia gravis with purely ocular symptoms at onset: a multivariable model development and validation

Background

About half of myasthenia gravis (MG) patients with purely ocular symptoms at onset progress to generalized myasthenia gravis (gMG).

Objectives

To develop and validate a model to predict the generalization of MG at 6 months after disease onset in patients with ocular-onset myasthenia gravis (OoMG).

Methods

Data of patients with OoMG were retrospectively collected from two tertiary hospitals in Germany and China. An accelerated failure time model was developed using the backward elimination method based on the German cohort to predict the generalization of OoMG. The model was then externally validated in the Chinese cohort, and its performance was assessed using Harrell's C-index and calibration plots.

Results

Four hundred and seventy-seven patients (275 from Germany and 202 from China) were eligible for inclusion. One hundred and three (37.5%) patients in the German cohort progressed from OoMG to gMG with a median follow-up time of 69 (32-116) months. The median time to generalization was 29 (16-71) months. The estimated cumulative probability of generalization was 30.5% [95% CI (confidence interval), 24.3-36.2%) at 5 years after disease onset. The final model, which was represented as a nomogram, included five clinical variables: sex, titer of anti-AChR antibody, status of anti-MuSK antibody, age at disease onset and the presence of other autoimmune disease. External validation of the model using the bootstrap showed a C-index of 0.670 (95% CI, 0.602-0.738). Calibration curves revealed moderate agreement of predicted and observed outcomes.

Conclusion

The nomogram is a good predictor for generalization in patients with OoMG that can be used to inform of the individual generalization risk, which might improve the clinical decision-making.

Ocular myasthenia gravis and risk factors for developing a secondary generalisation: description of a Spanish series

INTRODUCTION

Ocular myasthenia gravis (MG) is the most common phenotype of MG at onset. A variable percentage of these patients develop secondary generalisation; the risk factors for conversion and the protective effect of immunosuppressive treatment are currently controversial.

PATIENTS AND METHODS

We designed a retrospective single-centre study with the aim of describing the demographic, clinical, and laboratory characteristics of a Spanish cohort of patients with ocular MG from Hospital Universitario de Albacete from January 2008 to February 2020.

RESULTS

We selected 62 patients with ocular MG from a cohort of 91 patients with MG (68.1%). Median age at diagnosis was 68 (IQR, 52-75.3), and men accounted for 61.3% of the sample (n = 38). Most patients presented very late-onset ocular MG (n = 34, 54.8%). Binocular diplopia was the most frequent initial symptom (51.7%). The rate of progression to generalised MG was 50% (n = 31), with a median time of 6 months (IQR, 2-12.8). Female sex (OR: 5.46; 95% CI, 1.16-25-74; P= .03) and anti-acetylcholine receptor antibodies (OR: 8.86; 95% CI, 1.15-68.41; P = .04) were significantly associated with the risk of developing generalised MG.

CONCLUSIONS

The conversion rate observed in our series is relatively high. Generalisation of MG mainly occurs during the first 2 years of progression, and is strongly associated with female sex and especially with the presence of anti-acetylcholine receptor antibodies.

Risk for generalization in ocular onset myasthenia gravis: experience from a neuro-ophthalmology clinic

Conversion to generalized myasthenia gravis (GMG) within the first 2 years has been reported in 18-85% of patients with ocular myasthenia gravis (OMG). The aim of the study was to investigate the risk factors for generalization in patients with OMG admitted to a neuro-ophthalmology clinic and to determine if there were differences between patients with GMG with predominant bulbar (GMG-B) or extremity muscle (GMG-E) involvement according to the 6th and 24th-month Myasthenia Gravis Foundation of America classification ranks. Patients with OMG who were followed-up for at least 24 months were retrospectively analyzed. Demographic, clinical, laboratory features and treatment strategies that can be associated with generalization and time to generalization were evaluated. Of the 139 patients with OMG, 54 (39%) showed generalization with a mean time of 10.3 (range 2-24) months. GMG-B and GMG-E were diagnosed in 31 (22.3%) and 23 patients (16.5%), respectively. Seropositivity for acetylcholine receptor and muscle-specific tyrosine kinase antibodies, abnormal single-fiber electromyography (SFEMG), and the presence of thymic abnormalities (thymoma and hyperplasia) were factors associated with generalization on multivariate analysis without a significant difference between the GMG-B and GMG-E groups. In addition, an abnormal repetitive nerve stimulation test was related to a shortened time to generalization. Bilateral ptosis at onset was found as a risk factor for generalization. In a neuro-ophthalmology clinic, bilateral ptosis as an initial feature of OMG must be approached cautiously because it may be the first sign of impending GMG.

Prognostic factors for conversion to generalization in ocular myasthenia gravis

Patients with ocular myasthenia gravis (OMG) are frequently treated to prevent the development of generalized myasthenia gravis (GMG). This retrospective cohort study aimed to assess prognostic factors associated with conversion to GMG.We analyzed the time from the onset of OMG symptoms to GMG in relation to demographic variables, clinical findings, initial investigation results, and treatment regimens using Kaplan-Meier survival curves and multivariate Cox proportional regression analysis.Of 115 patients diagnosed with OMG (median follow-up time, 2.9 years), 28 (30.4%) developed GMG. The 2-year probability of GMG conversion was 23.7%. Patients with thymic abnormalities and a positive response to repetitive facial nerve stimulation had a significantly higher risk than those with negative results (hazard ratios [HR] 4.28, P < .001 and HR 3.84, P = .04, respectively). Treatment with immunosuppressants was found to be a preventive factor for secondary generalization (HR 0.36, P = .02).Patients with OMG had a low risk of developing GMG. Immunosuppressive treatments may mitigate disease progression. Chest imaging and repetitive nerve stimulation should be routinely performed to assess the risk of generalization.

Ocular myasthenia gravis: updates on an elusive target

PURPOSE OF REVIEW

Ocular myasthenia gravis (OMG) is a complex condition with heterogenous phenotypes and ill-defined diagnostic criteria. Understanding concomitant risk factors and autoimmune serology can help inform prognosis for generalization and guide treatment.

RECENT FINDINGS

Although antibodies to acetylcholine receptors or muscle-specific kinase likely increase risk of generalization, they are less frequent in OMG. Patients without either antibody tend to have a milder disease process and often have variable antibodies to other end-plate proteins such as LRP4, agrin, or cortactin. The treatment of OMG begins with pyridostigmine and is supplemented by oral prednisone if treatment-resistant or high risk for generalization. Variable oral prednisone regimens have been used with success and further immunosuppression may be best achieved with mycophenolate mofetil and azathioprine. Checkpoint inhibitor-induced myasthenia gravis is increasingly recognized and likely has high rates of mortality associated with myocarditis.

SUMMARY

Our understanding of OMG and its variable phenotypes continues to evolve. Autoantibody testing increasingly provides valuable diagnostic and prognostic information. Despite these improvements, a lack of quality treatment trials creates significant challenges for evidence-based management guidelines.

Ocular myasthenia gravis and risk factors for developing a secondary generalisation: Description of a Spanish series

INTRODUCTION

Ocular myasthenia gravis (MG) is the most common phenotype of MG at onset. A variable percentage of these patients develop secondary generalisation; the risk factors for conversion and the protective effect of immunosuppressive treatment are currently controversial.

PATIENTS AND METHODS

We designed a retrospective single-centre study with the aim of describing the demographic, clinical, and laboratory characteristics of a Spanish cohort of patients with ocular MG from Hospital Universitario de Albacete from January 2008 to February 2020.

RESULTS

We selected 62 patients with ocular MG from a cohort of 91 patients with MG (68.1%). Median age at diagnosis was 68 (IQR, 52-75.3), and men accounted for 61.3% of the sample (n = 38). Most patients presented very late-onset ocular MG (n = 34, 54.8%). Binocular diplopia was the most frequent initial symptom (51.7%). The rate of progression to generalised MG was 50% (n = 31), with a median time of 6 months (IQR, 2-12.8). Female sex (OR: 5.46; 95% CI, 1.16-25-74; p = .03) and anti-acetylcholine receptor antibodies (OR: 8.86; 95% CI, 1.15-68.41; p = .04) were significantly associated with the risk of developing generalised MG.

CONCLUSIONS

The conversion rate observed in our series is relatively high. Generalisation of MG mainly occurs during the first 2 years of progression, and is strongly associated with female sex and especially with the presence of anti-acetylcholine receptor antibodies.

Prediction of generalization of ocular myasthenia gravis under immunosuppressive therapy in Northwest China

BACKGROUND

It is well demonstrated that immunosuppressants can reduce, but not eliminate the risk of generalized development in ocular myasthenia gravis (OMG). In this study, we aimed to explore the predictive factors of generalized conversion of OMG patients who received immunosuppressive treatments.

METHODS

OMG patients under immunosuppressive treatments in Tangdu Hospital from June 2008 to June 2012 were retrospectively reviewed. Baseline clinical characteristics were documented. Patients were followed up regularly by face-to-face interview and the main outcome measure was generalized conversion. The logistic regression analysis was performed to determine the predictive factors of generalization of OMG.

RESULTS

Two hundred twenty-three eligible OMG patients completed the final follow-up visit and 38 (17.0%) progressed to generalized MG (GMG) at a median time to generalization of 0.9 year. Patients with adult onset and positive repetitive nerve stimulation (RNS) of facial or axillary nerve had higher conversion rate than those with juvenile onset and negative RNS (p = 0.001; p = 0.019; p = 0.015, respectively). Adult-onset patients converted earlier than juvenile-onset OMG patients (p = 0.014). Upon multivariate logistic regression analysis, age of onset (Odds ratio [OR] 1.023, 95% confidence interval [CI] 1.006-1.041, p = 0.007) and positive facial nerve RNS (OR 2.826, 95%CI 1.045-5.460, p = 0.038) were found to be positively associated with generalized development. Moreover, an obviously negative association was found for disease duration (OR 0.603, 95%CI 0.365-0.850, p = 0.019).

CONCLUSIONS

Age of onset, disease duration and facial nerve RNS test can predict generalized conversion of OMG under immunosuppressive therapy. Adult-onset, shorter disease duration and facial nerve RNS-positive OMG patients have a higher risk of generalized development.

Prognostic predictors of remission in ocular myasthenia after thymectomy

Background

Identifying prognostic predictors can assist in making clinical decisions. This study aimed to identify the potential predictors of remission in patients with ocular myasthenia gravis (OMG) after thymectomy.

Methods

OMG patients who had thymectomy between 2011 and 2017 were reviewed retrospectively. Clinical outcomes were assessed according to the Myasthenia Gravis Foundation of America Post-Intervention Status (MGFA-PIS). Kaplan-Meier analysis was used to estimate the cumulative probability of complete stable remission (CSR). Univariate and multivariable analyses with Cox proportional hazards regression were used to identify predictors of CSR.

Results

Fifty-one patients (23 male, 28 female) with a median age at OMG onset of 40 (range, 5-79) years were eligible for inclusion. Patients with thymomatous OMG (n=9) had a statistically older median age at disease onset [61 (range, 32-78) vs. 33.5 (range, 5-79) years, P=0.001], shorter duration from disease onset to thymectomy [3 (range, 2-24) vs. 10 (range, 1-132) months, P=0.004], and a higher rate of postoperative complication (44.4% vs. 9.5%, P=0.025), compared with non-thymomatous OMG (n=42). The estimated cumulative probability of CSR in the whole cohort was 41.8% (95% CI, 28.6-58.2%) 5 years after surgery. Age at onset of 40 years or younger (P=0.00016), female sex (P=0.069), and thymic hyperplasia (P=0.0061) were potential predictors under univariate analysis. However, only age at onset of 40 years or younger (HR: 4.117, 95% CI, 1.177-14.399, P=0.027) remained significant after multivariable analysis.

Conclusions

CSR could be achieved in about 40% of OMG patients 5 years after thymectomy and is likely to be predicted by age at onset of 40 years or younger.

Factors Affecting Generalization of Ocular Myasthenia Gravis in Patients With Positive Acetylcholine Receptor Antibody

PURPOSE

To evaluate the associated factors of conversion of ocular myasthenia gravis (OMG) to generalized myasthenia gravis (GMG) among patients with seropositive acetylcholine receptor antibody (AchR Ab).

DESIGN

Retrospective cohort study.

METHODS

Setting: Retrospective chart review.

PATIENT

Seventy-one OMG patients with seropositive AchR Ab presented during July 2009 and December 2016. The exclusion criteria were patients who (1) first presented with GMG, (2) were unable to identify the time of onset of OMG or GMG, (3) were unable to provide information about previous treatments before the onset of GMG, and (4) had incomplete or lost medical records.

OBSERVATION PROCEDURE

We collected demographic and clinical characteristics, including onset of OMG and GMG, presence of other autoimmune disorders, history of smoking, presence of thymic abnormalities, and medications received.

MAIN OUTCOME MEASURES

Conversion to GMG and time to conversion.

RESULTS

Thirty-six patients experienced conversion to GMG. Overall incidence of GMG was 14 (95% confidence interval [CI] 10.09-19.4) per 100 patient-years. Probability of conversion at 2 years was .37 (95% CI .27-.49). Overall median conversion time was 4.97 years. Cox proportional hazard model showed that risk factors were female sex (HR 2.52, 95% CI 1.04-6.10), history of smoking (HR 3.42, 95% CI 1.40-8.45), and thymic abnormalities (HR 1.82, 95% CI 0.91-3.67). Protective factors against conversion to GMG were receiving immunosuppressive agents (HR 0.42, 95% CI 0.19-0.97) and pyridostigmine (HR 0.37, 95% CI 0.14-0.93).

CONCLUSIONS

OMG patients with seropositive AchR Ab should be informed that taking pyridostigmine and/or immunosuppressive agents as well as smoking cessation might prevent conversion to GMG.

Generalization after ocular onset in myasthenia gravis: a case series in Germany

BACKGROUND AND PURPOSE

Approximately, 50% of myasthenia gravis (MG) patients initially present with purely ocular symptoms. Of these, about 60% will develop secondary generalized MG, typically within 2 years. Risk factors for secondary generalization are still controversial. In this study, we reviewed clinical parameters, thymic pathologies and medical treatments of MG patients with purely ocular symptoms at onset to investigate risk factors for secondary generalization.

METHODS

In this monocentric retrospective study, we reviewed consecutive patients who underwent robotic thymectomy between January 2003 and October 2017 in Charite Universitaetsmedizin Berlin. We used univariate and multivariate Cox proportional hazards regression models to identify factors associated with secondary generalization. Survival curves were plotted using Kaplan-Meier method and log-rank tests were performed to analyze the association between corticosteroids use and secondary generalization in subgroups defined by anti-AChR antibody status and thymic pathology.

RESULTS

One hundred and eighty of 572 MG patients who underwent robotic thymectomy were eligible for inclusion, of whom 110 (61.1%) developed a secondary generalized MG over a mean follow-up time of 23.6 months. The presence of a thymoma (HR 1.659, 95% CI (1.52-2.617), P = 0.029) was the only risk factor for secondary generalization in our series. Treating with corticosteroids was associated with a lower conversion rate in ocular myasthenia patients with thymic hyperplasia (n = 55, P = 0.028), but not with other thymic pathologies including thymoma and normal or atrophic thymus.

CONCLUSIONS

The conversion rate in ocular myasthenia was high in our series, predicted by the presence of a thymoma. Our findings suggest that corticosteroids can prevent secondary generalization in ocular myasthenia patients with thymic hyperplasia, which requires further research.