Antibody-associated Myasthenia Gravis Research Articles

Clinical features, treatment and prognosis of MuSK antibody-associated myasthenia gravis in Northwest China: a single-centre retrospective cohort study

Background and purposeTo summarize the clinical characteristics of patients with muscle-specific kinase antibody-associated myasthenia gravis (MuSK-MG) and to evaluate the therapeutic responses to different treatment regimes.MethodsEighteen MuSK-MG patients admitted in our department between October 2017 and September 2020 were included. Clinical parameters were collected and the responses to different immunosuppressive drugs were assessed by MGFA Postintervention Status (MGFA-PIS). Meanwhile, the correlation between QMG scores and MuSK antibody titers were analyzed and MuSK antibody (MuSK-ab) titers were compared before and after therapy based on different immunosuppressive treatment regimes.ResultsFemale predominance (ratio of females to males, 15:3) was evident in the study population, with the average onset age of (40.28 ± 18.57) years and the median disease course of 30.50 months (interquartile range [IQR], 17.50–44.75 months). Ocular manifestation was the most common onset symptom (11/18; 61.11%), and mild symmetrical ptosis was most frequent. Bulbar symptoms had the highest incidence of 88.89% over the entire disease course. Abnormal responses to RNS test were recorded most frequently on the musculus deltoideus (83.33%). All patients were treated with prednisone (Pred) alone or plus azathioprine (AZA), tacrolimus (TAC) or low-dose rituximab (RTX), and 17 (94.44%) of them achieved a favorable outcome defined as minimal manifestation (MM) or better. In general, an obvious positive correlation between QMG score and MuSK-ab titer (r = 0.710, P < 0.001) were found in all patients. A more significant reduction of MuSK-ab titers was observed in patients receiving TAC or RTX plus Pred than those receiving AZA plus Pred.ConclusionsThe prominent clinical manifestations of ocular and bulbar muscles involvements, together with abnormal RNS response mostly recorded on the musculus deltoideus and better efficacy associated with TAC or low-dose RTX plus Pred, provide a more exhaustive picture of MuSK-MG, particularly in Northwest China.

Case report

Myasthenia gravis (MG) is a rare autoimmune disease in which antibodies bind to acetylcholine receptors in the postsynaptic membrane at the neuromuscular junction. Muscle-specific kinase (MuSK) antibody-associated MG patients often have severe symptoms, including bulbar dysfunction, respiratory insufficiency, and atrophy of the facial and tongue muscles. Due to its fluctuating nature and the similarity to the symptoms other disorders MG is one of the most challenging medical diagnoses.Fluctuating character and the similarity of symptoms to those of other disorders make MG one of the most challenging medical diagnoses. Initial misdiagnosis of MuSK-MG can lead to worsening of symptoms. The diagnosis is confirmed by positive results on pharmacological testing, electrodiagnostictesting and serum antibodyassay. Symptomatic, immunoactive, and supportive approaches to therapy have very good effect and the prognosis is improved with precocious interventions.

Case report

Myasthenia gravis (MG) is a rare autoimmune disease in which antibodies bind to acetylcholine receptors in the postsynaptic membrane at the neuromuscular junction. Muscle-specific kinase (MuSK) antibody-associated MG patients often have severe symptoms, including bulbar dysfunction, respiratory insufficiency, and atrophy of the facial and tongue muscles. Due to its fluctuating nature and the similarity to the symptoms other disorders MG is one of the most challenging medical diagnoses.Fluctuating character and the similarity of symptoms to those of other disorders make MG one of the most challenging medical diagnoses. Initial misdiagnosis of MuSK-MG can lead to worsening of symptoms. The diagnosis is confirmed by positive results on pharmacological testing, electrodiagnostictesting and serum antibodyassay. Symptomatic, immunoactive, and supportive approaches to therapy have very good effect and the prognosis is improved with precocious interventions.

Longstanding and Refractory Anti-Muscle Specific Tyrosine Kinase Antibody-Associated Myasthenia Gravis (Anti-MuSK-MG) in a Child Successfully Treated with Rituximab

ABSTRACTAnti-muscle specific tyrosine kinase antibody-associated myasthenia gravis (MuSK-MG) is a rare subtype of MG characterized by more frequent relapses and a clinical course that is refractory to standard treatments. Rituximab, a monoclonal antibody targeting CD20+ B cells, has been used effectively in the adult population to achieve stable remission. We describe a pediatric patient with MuSK-MG who demonstrated an excellent response to rituximab after failing standard therapy.

Myasthenia Gravis-Our Experience in the Last Three Years with Interesting Associations

Background: Myasthenia gravis is a common immune mediated disease with a prevalence of 1 in 30000 populations. It is eminently treatable but when it presents atypically diagnosis can be missed. Aim: To look for the common and uncommon clinical features and antibody profile in patients with features of myasthenia gravis. Settings and design: Myasthenia gravis though well known to be associated with antibody to AchR receptor in the post synaptic membrane, a large group of patients are seronegative for AchR with atypical presentations. Anti- Titin antibody titre was done in 7 cases and anti-MUSK in 1 case when strongly indicated by clinical features. Materials and methods: 29 patients who were confirmed as Myasthenia gravis, seen by authors in the last 3 years were evaluated with anti AchR antibodies in all cases and; Anti-titin and Anti-musk antibodies when clinical indication was strong and patient could afford. Statistical analysis: Descriptive analysis was done as the number is small. Results and consideration: Maximum numbers of patients were seen in the younger age group. But patients with more serious disease, patients with Thymic and extrathymic Tumors, Anti-titin and musk associated patients were in the later age group. Thymic tumour has been not detected for nearly 10 years after disease onset in one case. Macroglossia, Motor neuron disease overlap is seen in one case which is relatively very rare. Though Myasthenia gravis is seen commonly in the young persons, Thymic and extrathymic tumors, Anti-titin antibody associated Myasthenia gravis is seen in later age group. Macroglossia and Motor neuron disease overlap features do not exclude MG.

Acetylcholine receptor binding antibody-associated myasthenia gravis and rhabdomyolysis induced by nivolumab in a patient with melanoma

We reported an 81-year-old woman with metastatic melanoma, in whom myasthenia gravis and rhabdomyolysis developed after nivolumab monotherapy. The first symptom of myasthenia gravis was dyspnea. Ultrasonography detected hypokinesis of the bilateral diaphragm suggesting myasthenia gravis, although there was no abnormal finding of the lungs in computed tomography images. Acetylcholine receptor binding antibodies were low-titer positive in the preserved serum before administration of nivolumab, strongly suggesting that the myasthenia gravis was a nivolumab-related immune adverse event. Despite the remarkable clinical benefits of immune checkpoint inhibitors for patients with advanced melanoma, it is important to recognize unexpected immune-related adverse events.

MRI and clinical studies of facial and bulbar muscle involvement in MuSk antibody-associated myasthenia gravis

MRI and clinical studies of facial and bulbar muscle involvement in MuSk antibody-associated myasthenia gravis

MRI and clinical studies of facial and bulbar muscle involvement in MuSK antibody-associated myasthenia gravis

A proportion of patients with myasthenia gravis (MG) without acetylcholine receptor (AChR) antibodies have antibodies to muscle-specific kinase (MuSK). MG with MuSK antibodies (MuSK-MG) is often associated with persistent bulbar involvement, including marked facial weakness and tongue muscle wasting. The extent of muscle wasting in MuSK-MG, and whether it is also found in the few acetylcholine receptor (AChR-MG) patients who have persistent bulbar involvement, is not clear. We studied 12 MuSK-MG patients and recruited 14 AChR-MG patients matched broadly for age, sex ratio, duration of disease and degree of ocular, bulbar and facial weakness. We used coronal and sagittal T1-weighted (T1W) and T2-weighted (T2W) magnetic resonance imaging (MRI) to assess muscle wasting in facial and tongue muscles. Hyperintense signal on T1W MRI and comparison of axial T1W sequences with cUTE sequences were used to assess fibrous/fatty tissue in the tongue. We compared the results with those of four patients with myotonic dystrophy and 12 healthy individuals. We correlated the changes with clinical and treatment histories, and established a new ocular-bulbar-facial-respiratory (OBFR) score. At the time of study, none of the clinical measures, including the OBFR score, differed between the two MG groups. MRI demonstrated thinning of the buccinator, orbicularis oris (O.oris) and orbicularis oculi (O.oculi) muscles in MuSK-MG patients compared with healthy controls, whereas thinning of these muscles was not significant in AChR-MG. Tongue areas with T1W high signal were increased in MuSK-MG patients and the intensity of the signal on axial T1W sequences was greater in MuSK-MG than in controls. To look for possible correlations between imaging and clinical findings, we pooled results from all MG patients. The duration of treatment with prednisolone at >40 mg on alternate days (AD) correlated positively with the percentage of tongue area with high signal (P = 0.006) and negatively with MRI measurements of individual muscles and with the mean muscle dimensions (P = 0.001). The new OBFR score correlated positively with current Myasthenia Gravis Foundation of America grades and with the percentage of high signal (P = 0.004) and negatively with the mean muscle dimensions (P < 0.001). The results show that bulbar and facial muscle weakness and wasting are associated with significant muscle atrophy and fatty replacement in MuSK-MG, which was not found in the AChR-MG patients. MuSK antibodies per se may predispose to muscle thinning, but the difficulties in obtaining clinical remission under steroid therapy in some patients, resulting in long duration of treatment with higher doses (>40 mg AD), may be an additional factor.