Refractory generalized myasthenia gravis with myasthenic incomplete ophthalmoplegia successfully treated with eculizumab

Purpose

This is a case of myasthenic incomplete ophthalmoplegia mimicking a partial cranial nerve 3 palsy both subjectively and objectively improving after treatment with eculizumab.

Observations

We chronicle a case of severe generalized myasthenia gravis including myasthenia masquerading as a partial cranial nerve 3 palsy, refractory to pyridostigmine, mycophenolate, prednisone, intravenous immunoglobulin and plasma exchange but responsive to eculizumab.

Conclusions and importance

This case demonstrates ocular and generalized myasthenia gravis refractory to several other therapies but amenable to eculizumab infusions, suggesting this medication may be of significant value in these difficult cases, and should be further explored for refractory ocular myasthenia gravis.

Ocular Myasthenia: Clinical Course and the Diagnostic Utility of Assaying Acetylcholine Receptor Antibodies

Myasthenia gravis (MG) is an autoimmune disease that causes neuromuscular junction transmission defect and has a predilection for the with neuromuscular junction transmission defect and predilection for extra-ocular and eyelid muscles. Most cases of ocular MG (OMG) convert later to generalised MG (GMG). Assaying acetylcholine receptor antibodies (AchRA) has been used to diagnose MG, but the reported sensitivity in OMG is lower (50%) than in GMG. We report the clinical course and the diagnostic yield of assaying AchRA in a Kuwaiti cohort of patients with OMG. We carried out a retrospective review of 47 patients diagnosed with OMG who were tested for AchRA. Ancillary tests included the ice test, single-fibre electromyography (SFMEG), and repetitive nerve stimulation electromyography (RNS). Progression to GMG occurred in 51% of OMG patients with a mean time to progression of 12.1 months (range 4 to 20 months). AchRAs were positive in 46 of 47 cases (98%), while SFEMG was positive in 31 of 34 cases (91.1%). Older age (44.25 years versus 38 years, p < .05) and higher AchRA titre (2.0 nmol/L versus 1.27 nmol/L, p < .05) were significantly associated with conversion to GMG. We have found a high rate of AchRA seropositivity in relatively younger subjects of OMG. Higher AchRA titres and older age were associated with conversion to GMG, usually within the first 2 years.

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.

New onset of ocular myasthenia gravis in a patient with COVID-19: a novel case report and literature review

The novel coronavirus outbreak of SARS-CoV-2 first began in Wuhan, China, in December 2019. The most striking manifestation of SARS-CoV-2 is atypical pneumonia and respiratory complications; however, various neurological manifestations are now well recognized. Currently, there have been very few case reports regarding COVID-19 in patients with a known history of myasthenia gravis. Myasthenia gravis (MG) causes muscle weakness, especially respiratory muscles, in high-risk COVID-19 patients, which can lead to severe respiratory compromise. There are few reported cases of severe myasthenia crisis following COVID-19, likely due to the involvement of the respiratory apparatus and the use of immunosuppressive medication. We report the first case of ocular MG developing secondary to COVID-19 infection in a 65-year-old woman. Two weeks prior to hospitalization, the patient suffered from cough, fever, and diarrhea and was found to be positive for COVID-19 via a nasopharyngeal RT-PCR swab test. The electrodiagnostic test showed decremental response over more than 10% on repetitive nerve stimulation test of orbicularis oculi. She tested positive for antibodies against acetylcholine receptor. COVID-19 is known to cause the release of inflammatory cytokines, leading to immune-mediated damage. MG is an immune-mediated disorder caused by molecular mimicry and autoantibodies against the neuromuscular junction.

Sensitivity and specificity of single-fibre EMG in the diagnosis of ocular myasthenia varies accordingly to clinical presentation

BACKGROUND AND PURPOSE

Single-fibre electromyography (SF-EMG) is considered as the most sensitive test for the diagnosis of MG. However, previous studies had limitations, such as a retrospective design, non-consecutive sampling, incorporation bias or were performed in small or mixed populations. Our aims were to determine the diagnostic sensitivity and specificity of SF-EMG of the orbicularis oculi in OMG and the utility of this test in relation to patients' clinical presentation.

MATERIALS AND METHODS

We studied 232 consecutive patients referred to the SF-EMG laboratory for a suspected OMG. Stimulated SF-EMG was performed on the orbicularis oculi muscle.

RESULTS

OMG was diagnosed in 165 cases and other disorders (OD) in 67. SF-EMG showed a sensitivity of 0.79 (95% CI 0.73-0.85) and a specificity of 0.80 (95% CI 0.71-0.90). False negative results were associated with mild symptoms and with isolated diplopia. Comparison of the diagnostic yield among patients with different clinical presentations showed a similar diagnostic accuracy of SF-EMG in patients with ptosis and in patients with ptosis and diplopia, significantly higher than in patients with isolated diplopia (P < 0.0001). Twenty-two patients with OMG presenting with isolated ptosis or diplopia, who initially tested negative, were re-tested in relation to a worsening of their symptoms showing a positivisation in 91% of cases.

CONCLUSIONS

SF-EMG on the orbicularis oculi muscle is very sensitive in patients with ptosis. In contrast, in patients with isolated diplopia SF-EMG does not exclude OMG. Therefore, the interpretation of the results of the test should take into account the patients' clinical presentation.

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.

Antibody profile may predict outcome in ocular myasthenia gravis

An unsolved issue remains whether there are clinical and immunological features to predict in a single patient the risk of conversion from ocular Myasthenia Gravis (OMG) to generalized disease (GMG) as 50-60% of patients may progress within 1-2 years since onset. Anti-acetylcholine receptor antibodies (AChR Abs) are found in up to 50% of OMG patients; muscle-specific tyrosine kinase antibodies (MuSK-Abs) are present in about 70% of the whole seronegative (SN), who usually develop a severe disease with bulbar involvement. We surveyed a cohort of 175 OMG patients with purely ocular symptoms and we compare the outcome of patients with antibodies to AChR or to MuSK with those seronegative for both Abs (DSN). All patients had purely ocular signs for at least 24 months. Gender, age at onset, time to generalization or to worsening in quantitative ocular QMG scores, electrophysiological results were analyzed. Males were 58.9%, females 41.1%. Patients with late onset of symptoms after 50 years (LOMG) were 78.3%. We assayed anti-MuSK-Abs in 4.7%, anti-AChR Abs in 38.5%; 57.3% were defined DSN. Thirty-seven patients (21.1%) progressed to GMG during the observational time: 23 were females, 62% of the whole group of the generalized subjects, 75% of MuSK-positive OMG converted to GMG versus the 26.2% of AChR positive and 13.7% of DSN. Statistical analysis showed that gender and presence of antibodies either to AChR or to MuSK were independent predictors of worse outcome; the DSN subjects had lower risk of conversion to GMG.

A retrospective study of acetylcholine receptor antibody positive ocular myasthenia in the West of Scotland

Ocular myasthenia is the milder end of the myasthenia gravis spectrum but treatment can be challenging especially in older patients. We retrospectively studied all patients on our database with ocular myasthenia (OMG), positive for acetylcholine receptor (AChR) antibodies. We identified 93 patients (64 men and 29 women). The mean age at disease onset was 63y, median 68y. Most (72%) experienced ptosis with diplopia; 19% experienced ptosis alone, while 7.5% complained of diplopia without ptosis. As expected, pyridostigmine was commenced early at diagnosis in the majority (69%) and 20% were still receiving pyridostigmine at final review. Immunosuppression was prescribed in 50%. Seven patients had ptosis repair surgery; 20 patients used prisms at some stage. >75% had several comorbidities. Our OMG cohort is an older population with several comorbidities. Final outcomes in those who received immunosuppression were similar to those who had not.

Factors affecting outcome in ocular myasthenia gravis

AIM OF THE STUDY

50%-60% of patients with ocular myasthenia gravis (OMG) progress to generalized myasthenia gravis (GMG) within two years. The aim of our study was to explore factors affecting prognosis of OMG and to test the predictive role of several independent clinical variables.

MATERIALS AND METHODS

We reviewed a cohort of 168 Caucasian patients followed from September 2000 to January 2016. Several independent variables were considered as prognostic factors: gender, age of onset, results on electrophysiological tests, presence and level of antibodies against acetylcholine receptors (AChR Abs), treatments, thymic abnormalities. The primary outcome was the progression to GMG and/or the presence of bulbar symptoms. Secondary outcomes were either achievement of sustained minimal manifestation status or worsening in ocular quantitative MG subscore (O-QMGS) or worsening in total QMG score (T-QMGS), assessed by Myasthenia Gravis Foundation of America (MGFA) quantitative scores. Changes in mental and physical subscores of health-related quality of life (HRQoL) were assessed with SF-36 questionnaire. Variance analysis was used to interpret the differences between AChR Ab titers at different times of follow up among the generalized and non-generalized patients.

RESULTS

Conversion to GMG occurred in 18.4% of patients; it was significantly associated with sex, later onset of disease and anti-AChR Ab positivity. Antibody titer above the mean value of 25.8 pmol/mL showed no significant effect on generalization. Sex and late onset of disease significantly affected T-QMGS worsening. None of the other independent variables significantly affected O-QMGS and HRQoL.

CONCLUSIONS

Sex, later onset and anti-AChR Ab positivity were significantly associated with clinical worsening.