Abstract
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.
Highlights
Since the first description of muscle-specific kinase antibody (MuSK-ab) as a novel autoantibody in 2001 [1], MuSK antibody-associated myasthenia gravis (MuSKMG) has been regarded as an MG subtype with uniqueZhao et al BMC Neurol (2021) 21:428 molecular immunology underpinning the pathology and clinical characteristics
Given the fact that the non-complement activating IgG4 subclass is dominant in muscle-specific kinase antibody-associated myasthenia gravis (MuSK-MG), a great number of studies have concentrated on the development of new treatment regimens over the past two decades
The therapeutic efficacy and longterm outcome of other immunosuppressive agents such as tacrolimus (TAC) in the treatment of MuSK-MG has been rarely reported [8]. In this retrospective cohort study, we reviewed the medical records of all MuSK-MG patients admitted in our department from October 2017 to September 2020 and summarized the clinical characteristics of MuSKMG
Summary
Zhao et al BMC Neurol (2021) 21:428 molecular immunology underpinning the pathology and clinical characteristics. It accounts for about 4–5% of all MG patients and one-third of acetylcholine receptor antibody (AChR-ab)-negative MG patients [2, 3]. Unlike AChR antibody-associated MG (AChR-MG), MuSK-MG displays different clinical profile including prominent involvement of bulbar and cranial muscles and rapid progression with myasthenic crisis at an earlier stage of disease course and shows a limited response to conventional treatments such as acetylcholinesterase inhibitors (ACEI), intravenous immunoglobulin (IVIg) and thymectomy [4, 5]. To 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
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