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Hayashi M. Pathophysiology of Childhood-Onset Myasthenia: Abnormalities of Neuromuscular Junction and Autoimmunity and Its Background. PATHOPHYSIOLOGY 2023; 30:599-617. [PMID: 38133144 PMCID: PMC10747330 DOI: 10.3390/pathophysiology30040043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
The pathophysiology of myasthenia gravis (MG) has been largely elucidated over the past half century, and treatment methods have advanced. However, the number of cases of childhood-onset MG is smaller than that of adult MG, and the treatment of childhood-onset MG has continued to be based on research in the adult field. Research on pathophysiology and treatment methods that account for the unique growth and development of children is now desired. According to an epidemiological survey conducted by the Ministry of Health, Labour and Welfare of Japan, the number of patients with MG by age of onset in Japan is high in early childhood. In recent years, MG has been reported from many countries around the world, but the pattern of the number of patients by age of onset differs between East Asia and Western Europe, confirming that the Japanese pattern is common in East Asia. Furthermore, there are racial differences in autoimmune MG and congenital myasthenic syndromes according to immunogenetic background, and their pathophysiology and relationships are gradually becoming clear. In addition, treatment options are also recognized in different regions of the world. In this review article, I will present recent findings focusing on the differences in pathophysiology.
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Affiliation(s)
- Masatoshi Hayashi
- Department of Pediatrics, Uwajima City Hospital, Uwajima 798-8510, Japan
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2
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Abstract
Myasthenia gravis (MG) diagnosis is primarily clinically based. By the end of the clinical evaluation, clinicians have a sense as to whether presenting symptoms and elicited signs are weakly or strongly supportive of MG. Diagnostic tests can reaffirm the clinicians' impression. Edrophonium testing is rarely used but helpful in cases of measurable ptosis. Decremental response on slow-frequency repetitive nerve stimulation has a modest diagnostic yield in ocular MG but is helpful in generalized MG cases. The most sensitive test is single-fiber electromyography. In this article, the authors review the diagnostic testing approach of practicing clinicians for suspected MG cases.
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Affiliation(s)
- Mamatha Pasnoor
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA.
| | - Mazen M Dimachkie
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
| | - Constantine Farmakidis
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
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Nagappa M, Mahadevan A, Gangadhar Y, Patil SA, Bokolia S, Bindu PS, Sinha S, Taly AB. Autoantibodies in acquired myasthenia gravis: Clinical phenotype and immunological correlation. Acta Neurol Scand 2019; 139:428-437. [PMID: 30693486 DOI: 10.1111/ane.13071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 12/25/2018] [Accepted: 01/04/2019] [Indexed: 12/26/2022]
Abstract
BACKGROUND Data on antibody profile in myasthenia gravis (MG) from India are limited. OBJECTIVES To investigate antibody profile in patients with MG and their clinical correlates. PATIENTS AND METHODS Patients of MG (n = 85, M:F::1.1:1, mean age: 39.29 ± 17.3 years, mean symptom duration: 72.94 ± 91.8 months) were evaluated for clinical features, MG foundation of America (MGFA) score, response to treatment, and outcome at last follow-up. Antibodies to acetylcholine receptor (AChR), muscle-specific kinase (MUSK), titin and ryanodine receptor (RYR) were analysed using ELISA. RESULTS Based on the regional distribution of weakness, the cohort could be categorized as: generalized: 60, ocular: 16 and oculo-bulbar: 9. Sixty patients were followed up for a mean duration of 26.74 ± 13.8 months. Outcome at last follow-up was as follows: remission-22, no remission-33 and dead-5. AChR and MUSK antibodies were detected in 58 and 8 patients, respectively. Frequency of generalized MG, worse MGFA score during the disease course and thymomatous histology significantly correlated with presence of AChR-antibodies, though outcome at last follow-up was comparable between AChR-antibody positive and negative groups. Patients with MUSK antibodies had oculo-bulbar or generalized MG and frequent respiratory crisis, but majority improved or remitted with treatment. Titin antibodies were detected in 31.8% and RYR antibodies in 32.9%. Their presence did not correlate with age at onset of MG, severity or presence of thymoma. CONCLUSION This report highlights the spectrum of antibodies in MG in an Indian cohort. AChR-antibody positivity correlated with clinical severity. Outcome was good in majority of MUSK antibody-positive MG. The role of other antibodies, complementary vs epiphenomenon, remains open.
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Affiliation(s)
- Madhu Nagappa
- Department of Neurology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
- Neuromuscular Laboratory (NML) Neurobiology Research Centre (NBRC) National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Anita Mahadevan
- Neuromuscular Laboratory (NML) Neurobiology Research Centre (NBRC) National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
- Department of Neuropathology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Yashwanth Gangadhar
- Neuromuscular Laboratory (NML) Neurobiology Research Centre (NBRC) National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
- Department of Neuropathology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Shripad A. Patil
- Department of Neuromicrobiology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Suresh Bokolia
- Department of Neuromicrobiology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Parayil S. Bindu
- Department of Neurology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
- Neuromuscular Laboratory (NML) Neurobiology Research Centre (NBRC) National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Sanjib Sinha
- Department of Neurology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
| | - Arun B. Taly
- Department of Neurology National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
- Neuromuscular Laboratory (NML) Neurobiology Research Centre (NBRC) National Institute of Mental Health and Neurosciences (NIMHANS) Bangalore India
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Barraud C, Desguerre I, Barnerias C, Gitiaux C, Boulay C, Chabrol B. Clinical features and evolution of juvenile myasthenia gravis in a French cohort. Muscle Nerve 2017; 57:603-609. [PMID: 28877546 DOI: 10.1002/mus.25965] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2017] [Indexed: 01/17/2023]
Abstract
INTRODUCTION In this study we determined the clinical, paraclinical, and treatment-related features of juvenile myasthenia gravis (JMG) as well as the clinical course in a cohort of French children. METHODS We conducted a retrospective study of 40 patients with JMG at 2 French pediatric neurology departments from April 2004 to April 2014. RESULTS Among the patients, 70% had generalized JMG, 52% had positive acetylcholine receptor antibodies, 8% had muscle-specific kinase antibodies, and 40% were seronegative. Treatment with acetylcholinesterase inhibitors was effective and sufficient in 47% of patients. The 6 patients with generalized JMG treated with rituximab and/or immunoadsorption showed improvement. Thirty percent of the patients required hospitalization in an intensive care unit during follow-up (mean 4.7 years). Remission without treatment occurred in 18% of patients. DISCUSSION As with adults, JMG has high morbidity, particularly among children with generalized symptoms, and rituximab should be considered early in the course of the disease as a second-line treatment. Muscle Nerve 57: 603-609, 2018.
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Affiliation(s)
- Coline Barraud
- APHM Service de Neuropédiatrie, Hôpital La Timone-Enfants, 264, Rue St Pierre Marseille, 13385, cedex 5, France
- Aix-Marseille Université, Marseille, France
| | - Isabelle Desguerre
- APHP Service de Neuropédiatrie, Hôpital Necker-Enfants Malades, Paris, France
- Université René Descartes, Paris, France
| | - Christine Barnerias
- APHP Service de Neuropédiatrie, Hôpital Necker-Enfants Malades, Paris, France
| | - Cyril Gitiaux
- Aix-Marseille Université, Marseille, France
- APHP Service de Neuropédiatrie, Hôpital Necker-Enfants Malades, Paris, France
| | - Christophe Boulay
- APHM Service de Neuropédiatrie, Hôpital La Timone-Enfants, 264, Rue St Pierre Marseille, 13385, cedex 5, France
- Aix-Marseille Université, Marseille, France
| | - Brigitte Chabrol
- APHM Service de Neuropédiatrie, Hôpital La Timone-Enfants, 264, Rue St Pierre Marseille, 13385, cedex 5, France
- Aix-Marseille Université, Marseille, France
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Zouvelou V, Velonakis G. Prepubertal muscle-specific kinase myasthenia with a long and benign natural course. Muscle Nerve 2016; 53:989. [DOI: 10.1002/mus.25010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Vasiliki Zouvelou
- Department of Neurology, University of Athens, Aeginitio Hospital, 74 Vas. Sophias Avenue, Athens 11528; Greece
| | - Georgios Velonakis
- Research Unit of Radiology and Medical Imaging, University of Athens, Athens; Greece
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Gungor-Tuncer O, Orhan EK, Yilmaz V, Parman Y, Oflazer P, Saruhan-Direskeneli G, Deymeer F. Prepubertal anti-Musk positive myasthenia gravis with long remission. Neuromuscul Disord 2014; 24:36-9. [DOI: 10.1016/j.nmd.2013.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/01/2013] [Accepted: 07/29/2013] [Indexed: 10/26/2022]
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Yilmaz S, Gokben S, Serdaroglu G, Akcay A. Early-onset acquired myasthenia gravis secondary to anti-muscle-specific kinase autoantibodies. J Child Neurol 2014; 29:108-10. [PMID: 23234677 DOI: 10.1177/0883073812467689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autoimmune myasthenia gravis is rarely seen during infancy. Similar to adults, 85% to 90% of generalized pediatric myasthenia gravis cases have acetylcholine receptor antibodies. Approximately 30% of the remaining cases have antibodies against muscle-specific kinase. Information on the clinical course, treatment alternatives, and prognosis of pediatric muscle-specific kinase antibody-positive myasthenia gravis is limited because of the small number of cases. Here, we present a 14-month-old girl with muscle-specific kinase antibody-positive myasthenia gravis as one of the youngest patients described so far in the literature.
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Affiliation(s)
- Sanem Yilmaz
- 1Department of Pediatrics, Division of Child Neurology, Ege University Faculty of Medicine, Izmir, Turkey
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Takahashi Y, Sugiyama M, Ueda Y, Itoh T, Yagyu K, Shiraishi H, Ukeba-Terashita Y, Nakanishi M, Nagashima T, Imai T, Motomura M, Saitoh S. Childhood-onset anti-MuSK antibody positive myasthenia gravis demonstrates a distinct clinical course. Brain Dev 2012; 34:784-6. [PMID: 22277190 DOI: 10.1016/j.braindev.2011.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 10/27/2011] [Accepted: 12/29/2011] [Indexed: 11/19/2022]
Abstract
Anti-muscle-specific tyrosine kinase antibody (MuSK-Ab) is the second most frequent autoantibody identified in adult patients with myasthenia gravis (MG). Adult patients with MuSK-Ab demonstrate characteristic clinical features but very little information is available for childhood-onset patients with MuSK-positive MG. We report a childhood-onset female patient with MuSK-positive MG. This patient showed basic clinical features compatible with adult-onset MuSK-positive MG, but some features, including spontaneous improvement, are distinct from those in adult patients. Serial examination of MuSK-Ab titers revealed a gross correlation with clinical severity despite significantly high titers throughout the clinical course. Therefore, childhood-onset MuSK-positive MG may demonstrate a distinct clinical characteristics in the early period of illness.
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Affiliation(s)
- Yumi Takahashi
- Department of Pediatrics, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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Abstract
PURPOSE OF REVIEW This review discusses recent studies on myasthenia gravis with onset in childhood (juvenile myasthenia gravis) and neonatal myasthenia gravis. RECENT FINDINGS The occurrence of myasthenia gravis in childhood is strongly influenced by genetic and environmental factors. Juvenile myasthenia gravis is associated with antibodies to the acetylcholine receptor (AChR) in most patients. Thymoma is rare, but often malignant in children. The frequency of juvenile myasthenia gravis with antibodies to the muscle-specific kinase (MuSK) varies markedly in different countries; some distinct features have been described. Management of juvenile myasthenia gravis does not differ, on the whole, from that of adult myasthenia gravis. Timing of thymectomy in young children is still controversial. Maternal antifetal type AChR antibodies can cause persistent focal weakness in the offspring, while neonatal myasthenia gravis associated with MuSK antibodies is often a severe and protracted albeit transient disease. SUMMARY Juvenile myasthenia gravis, like its adult-onset counterpart, is a heterogeneous disease. Clinical presentation is influenced by antibody status, ethnicity and age of onset. Treatment is very effective, but guidelines and controlled trials are needed.The risk for neonatal myasthenia gravis appears to be markedly influenced by maternal antibody subclass and antigen specificity. Adequate treatment in mothers can reduce both frequency and severity of neonatal disease.
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Liu GT, Volpe NJ, Galetta SL. Eyelid and facial nerve disorders. Neuroophthalmology 2010. [DOI: 10.1016/b978-1-4160-2311-1.00014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Kostera-Pruszczyk A, Kwiecinski H. Juvenile seropositive myasthenia gravis with anti-MuSK antibody after thymectomy. J Neurol 2009; 256:1780-1. [DOI: 10.1007/s00415-009-5215-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/08/2009] [Accepted: 06/08/2009] [Indexed: 10/20/2022]
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Anlar B, Yilmaz V, Saruhan-Direskeneli G. Long remission in muscle-specific kinase antibody-positive juvenile myasthenia. Pediatr Neurol 2009; 40:455-6. [PMID: 19433280 DOI: 10.1016/j.pediatrneurol.2008.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/18/2008] [Accepted: 11/25/2008] [Indexed: 10/20/2022]
Abstract
The clinical course of anti-muscle specific kinase-positive myasthenia in children has been little reported. Described here is the case of an 8 year-old boy who presented with ptosis and generalized weakness, which resolved within 1 month without any immunomodulatory treatment. This spontaneous remission lasted 6 years and was then followed by a relapse with bulbar symptoms. The patient was put on plasmapheresis; after initial benefit, symptoms worsened and serum antibody levels persisted. This case constitutes an example of the variability of the clinical presentation, course, and therapeutic response in anti-muscle specific kinase-positive myasthenia in childhood.
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Affiliation(s)
- Banu Anlar
- Department of Pediatric Neurology, Hacettepe University, Ankara, Turkey.
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Evoli A, Bianchi MR, Riso R, Minicuci GM, Batocchi AP, Servidei S, Scuderi F, Bartoccioni E. Response to therapy in myasthenia gravis with anti-MuSK antibodies. Ann N Y Acad Sci 2008; 1132:76-83. [PMID: 18567856 DOI: 10.1196/annals.1405.012] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
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.
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Affiliation(s)
- Amelia Evoli
- Department of Neurosciences, Catholic University, Largo F. Vito 1, 00168 Rome, Italy.
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Millichap JG. Infantile Onset Myasthenia Gravis with MuSK Antibodies. Pediatr Neurol Briefs 2006. [DOI: 10.15844/pedneurbriefs-20-8-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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