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Oh SJ. Amifampridines are the Most Effective Drugs for Treating Lambert-Eaton Myasthenic Syndrome With a Focus on Pediatric Lambert-Eaton Myasthenic Syndrome. J Clin Neurol 2024; 20:353-361. [PMID: 38951970 PMCID: PMC11220352 DOI: 10.3988/jcn.2024.0018] [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: 01/09/2024] [Revised: 04/02/2024] [Accepted: 04/12/2024] [Indexed: 07/03/2024] Open
Abstract
In 1983, the first successful trial of 3,4-diaminopyridine (3,4-DAP) in Lambert-Eaton myasthenic syndrome (LEMS) was reported. Efficacy of amifampridine (3,4-DAP and 3,4-diaminopyridine phosphate [3,4-DAPP]) for symptomatic treatment in LEMS was proven by seven randomized studies in 3,4-DAP and two randomized studies in 3,4-DAPP. US Food Drug Administration approved 3,4-DAPP usage for adult LEMS in 2018 and for pediatric LEMS in 2022. Nineteen pediatric LEMS cases were identified in the literature. Compared with adult LEMS, the rate of malignancy is low as expected and the rate of dysautonomia is also low in pediatric LEMS. Unexpected finding is two cases of pediatric LEMS following antecedent infection. Amifampridine can be safely used as long the daily dose is less than 80 mg a day for adult LEMS patients and less than 30 mg a day for pediatric LEMS patients. Amifampridines can be supplemented with a liberal amount of pyridostigmine for long term usage. Amifampridine was used as symptomatic treatment in eight (42%) of 19 pediatric LEMS patients: 3,4-DAP in six and 3,4-DAPP in two patients. The most common practice of 3,4-DAP was a combination with pyridostigmine in four patients. With 3,4-DAP, normal activity was reported in 3 cases and mild to moderate-improvement in other 3 cases. In two patients with 3,4-DAPP, significant improvement in one and no improvement in one. Amifampridines are proven to be effective and safe drugs for the symptomatic treatment without serious side reaction in adults as well as in children as long as the dosage is properly adhered.
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Affiliation(s)
- Shin J Oh
- Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Chisari CG, Sciacca G, Reggio E, Terravecchia C, Patti F, Zappia M. Subclinical involvement of eye movements detected by video-based eye tracking in myasthenia gravis. Neurol Sci 2023:10.1007/s10072-023-06736-6. [DOI: 10.1007/s10072-023-06736-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/04/2023] [Indexed: 03/29/2023]
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Treatment and Management of Disorders of the Neuromuscular Junction. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00019-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Introduction: The present status of amifampridine (AFP) for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) is reviewed. Areas covered: All relevant literature identified through a PubMed search under treatment of LEMS, aminopyridine, and amifampridine are reviewed. An expert opinion on AFP was formulated. Expert opinion: AFPs, 3,4-DAP and 3,4-DAPP, are the most studied drugs in neuromuscular diseases. Randomized and non-randomized studies showed the most effective drug as symptomatic medication for LEMS. AFPs are safe and tolerable. Thus, AFPs should be the drug of choice for the symptomatic treatment in LEMS. As long as the daily dose is less than 80 mg a day, there is no concern for the serious side-reaction, seizure. Because of short-acting drug effects, it should be given three or four times a day. Peri-oral and finger paresthesia, the most common side-reaction, is accepted as a sign of drug-intake by many patients. Gastro-intestinal side reactions, the next common side-reaction of AFPs, are tolerable. AFPs are also the drug of choice and life-saving for LEMS crisis. For the long-term usage, it is proven to be safe and AFPs can be supplemented with liberal amount of pyridostigmine to sustain a symptomatic improvement without any undue side-reaction.
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Affiliation(s)
- Shin J Oh
- Department of Neurology, University of Alabama , Birmingham , AL , USA
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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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Yonemoto K, Nomura S, Shimizu A, Sakajiri K, Nitta E. [A case of Miller Fisher syndrome with a false-positive edrophonium test]. Rinsho Shinkeigaku 2019; 59:345-348. [PMID: 31142707 DOI: 10.5692/clinicalneurol.cn-001236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A 69-year-old woman presented with acute bilateral ptosis, ophthalmoplegia, ataxia, and hyporeflexia in the extremities following an antecedent upper respiratory infection. We suspected that she had Miller Fisher syndrome (MFS) and performed an edrophonium test (ET) to rule out myasthenia gravis (MG). Edrophonium chloride improved the patient's bilateral ptosis, but not her ophthalmoplegia. Given the absence of the waning phenomenon on electrophysiological examination, the anti-acetylcholine receptor antibody, and a diurnal variation of symptoms, we concluded that the ET result was a false-positive. A diagnosis of MFS was confirmed by the presence of a positive anti-GQ1b antibody. To our knowledge, this is the first case report of MFS with a false-positive ET.
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Affiliation(s)
- Kosuke Yonemoto
- Department of Neurology, National Hospital Organization Kanazawa Medical Center
| | - Shunichi Nomura
- Department of Neurology, National Hospital Organization Kanazawa Medical Center
| | - Ai Shimizu
- Department of Neurology, Kanazawa University School of Medicine
| | - Kenichi Sakajiri
- Department of Neurology, National Hospital Organization Kanazawa Medical Center
| | - Eishun Nitta
- Department of Neurology, National Hospital Organization Kanazawa Medical Center
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Huang K, Luo YB, Yang H. Autoimmune Channelopathies at Neuromuscular Junction. Front Neurol 2019; 10:516. [PMID: 31156543 PMCID: PMC6533877 DOI: 10.3389/fneur.2019.00516] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/30/2019] [Indexed: 12/22/2022] Open
Abstract
The neuromuscular junction, also called myoneural junction, is a site of chemical communication between a nerve fiber and a muscle cell. There are many types of channels at neuromuscular junction that play indispensable roles in neuromuscular signal transmission, such as voltage-gated calcium channels and voltage-gated potassium channels on presynaptic membrane, and acetylcholine receptors on post-synaptic membrane. Over the last two decades, our understanding of the role that autoantibodies play in neuromuscular junction disorders has been greatly improved. Antibodies against these channels cause a heterogeneous group of diseases, such as Lambert-Eaton syndrome, Isaacs' syndrome and myasthenia gravis. Lambert-Eaton syndrome is characterized by late onset of fatigue, skeletal muscle weakness, and autonomic symptoms. Patients with Isaacs' syndrome demonstrate muscle cramps and fasciculation. Myasthenia gravis is the most common autoimmune neuromuscular junction channelopathy characterized by fluctuation of muscle weakness. All these disorders have a high risk of tumor. Although these channelopathies share some common features, they differ for clinical features, antibodies profile, neurophysiological features, and treatments. The purpose of this review is to give a comprehensive insight on recent advances in autoimmune channelopathies at the neuromuscular junction.
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Affiliation(s)
- Kun Huang
- Neurology Department, Xiangya Hospital, Central South University, Changsha, China.,Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yue-Bei Luo
- Neurology Department, Xiangya Hospital, Central South University, Changsha, China
| | - Huan Yang
- Neurology Department, Xiangya Hospital, Central South University, Changsha, China
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Italian recommendations for the diagnosis and treatment of myasthenia gravis. Neurol Sci 2019; 40:1111-1124. [PMID: 30778878 DOI: 10.1007/s10072-019-03746-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/31/2019] [Indexed: 12/30/2022]
Abstract
Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.
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Oh SJ, Jeong D, Lee I, Alsharabati M. Repetitive nerve stimulation test in myasthenic crisis. Muscle Nerve 2019; 59:544-548. [PMID: 30488463 DOI: 10.1002/mus.26390] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 11/18/2018] [Accepted: 11/21/2018] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Herein we report our experience with the repetitive nerve stimulation (RNS) test in myasthenia gravis (MG) crisis. METHODS The various parameters of the RNS tests in 26 patients with MG crisis were analyzed. RESULTS In 18 (69%) patients, MG crisis is the first manifestation of MG. RNS tests were abnormal in 24 (92%) patients by decrement at low-rate stimulation in any of 4 tested muscles. Three patterns of abnormality were found: MG pattern (decrement at low-rate stimulation) in 23 patients; Lambert-Eaton myasthenic syndrome pattern in 1 patient; and cholinergic crisis pattern in 1 patient. DISCUSSION During MG crisis, the RNS test can serve as a rapid and sensitive diagnostic tool for MG in a majority of patients. Muscle Nerve 59:544-544, 2019.
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Affiliation(s)
- Shin J Oh
- Department of Neurology, University of Alabama at Birmingham, UAB Station, Birmingham, Alabama, 35294, USA
| | - Dushin Jeong
- Department of Neurology, University of Alabama at Birmingham, UAB Station, Birmingham, Alabama, 35294, USA.,Department of Neurology College of Medicine Soonchunhayng University, Cheonan, Republic of Korea
| | - Ikjae Lee
- Department of Neurology, University of Alabama at Birmingham, UAB Station, Birmingham, Alabama, 35294, USA
| | - Mohammad Alsharabati
- Department of Neurology, University of Alabama at Birmingham, UAB Station, Birmingham, Alabama, 35294, USA
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Review of the Diagnostic Challenges of Lambert–Eaton Syndrome Revealed Through Three Case Reports. Can J Neurol Sci 2016; 43:635-47. [DOI: 10.1017/cjn.2016.268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AbstractLambert–Eaton syndrome (LES) is a rare immune-mediated disorder characterized by proximal leg weakness, autonomic symptoms and hypoactive tendon reflexes. The paraneoplastic form is associated with small-cell lung cancer in 50-60% of cases, whereas the remaining cases are found in younger adults with a higher likelihood of coexisting autoimmune disease. The early recognition of LES is crucial for improving clinical outcomes but remains a major challenge. In this review, we analyze the clinical characteristics and diagnostic considerations in treating LES through a series of three case studies, one of which showed definitive response to pyridostigmine and corticosteroid combination therapy, followed by spontaneous remission. Patients were assessed by image-based screening, serological testing and electrophysiological evaluations, which included respiratory and autonomic testing. A better understanding of the common pitfalls in the clinical, serological and neurophysiologic diagnosis of LES through assessment of typical LES dysfunction throughout the nervous system should enable improved recognition and treatment of this syndrome.
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Affiliation(s)
- Watcharasam Rattananan
- Department of Neurology; The University of Alabama at Birmingham; 1720 7th Avenue South, Sparks Center 200 Birmingham Alabama 35294 USA
| | - Mohammad Alsharabati
- Department of Neurology; The University of Alabama at Birmingham; 1720 7th Avenue South, Sparks Center 200 Birmingham Alabama 35294 USA
| | - Shin J. Oh
- Department of Neurology; The University of Alabama at Birmingham; 1720 7th Avenue South, Sparks Center 200 Birmingham Alabama 35294 USA
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Cherian A, Baheti NN, Iype T. Electrophysiological study in neuromuscular junction disorders. Ann Indian Acad Neurol 2013; 16:34-41. [PMID: 23661960 PMCID: PMC3644779 DOI: 10.4103/0972-2327.107690] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/13/2011] [Accepted: 07/01/2012] [Indexed: 11/20/2022] Open
Abstract
This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG) helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS). SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.
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Affiliation(s)
- Ajith Cherian
- Department of Neurology, Government Medical College, Trivandrum, Kerala, India
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13
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Miastenie e sindromi miasteniche. Neurologia 2011. [DOI: 10.1016/s1634-7072(11)70655-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Schmidt D. Signs in ocular myasthenia and pseudomyasthenia Differential diagnostic criteria: A clinical review. Neuroophthalmology 2009. [DOI: 10.3109/01658109509044590] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Meeking SA, Prittie J, Barton L. Myasthenia gravis associated with thymic neoplasia in a cat. J Vet Emerg Crit Care (San Antonio) 2008. [DOI: 10.1111/j.1476-4431.2008.00290.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Almeida DFD, Radaeli RDF, Melo Jr ACMNC. Ice pack test in the diagnosis of myasthenia gravis. ARQUIVOS DE NEURO-PSIQUIATRIA 2008; 66:96-8. [DOI: 10.1590/s0004-282x2008000100025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Fasano A, Evoli A, Piano C, Tonali P, Bentivoglio A. Myasthenia gravis: An unrecognized cause of head drop in Parkinson's disease. Parkinsonism Relat Disord 2008; 14:164-5. [DOI: 10.1016/j.parkreldis.2007.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2007] [Accepted: 02/27/2007] [Indexed: 10/23/2022]
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Abstract
OBJECTIVE To describe the clinical presentation, diagnosis, and treatment of myasthenia gravis (MG) while emphasizing the important role of the pharmacist. DATA SOURCES English-language articles from MEDLINE pertinent to MG study selection and data extraction: All relevant publications addressing MG management were considered, including prospective comparative trials, epidemiological studies, guideline statements, review articles, and editorials. Particular focus occurred on primary literature published after 1976, but limited amount(s) existed. The American Autoimmune Related Diseases Association, Autoimmune Information Network, Inc., Myasthenia Gravis Foundation of America, Inc. (MGFA), National Institute of Neurological Disorders and Stroke, and National Organization for Rare Disorders. DATA SYNTHESIS MG is an autoimmune disorder involving the neuromuscular junction causing characteristic weakness in voluntary muscle groups. To determine appropriate pharmacotherapy, one must characterize the disease based on the degree of function and region of muscles affected. MGFA established a classification system of the disease in order to assess severity. Contemporary treatments include cholinesterase inhibitors, corticosteroids, immodulating/immunosuppressive therapy, intravenous immune globulin, plasmapheresis, and thymectomy. Because of the lack of double-blind, placebo-controlled, randomized clinical trials, treatments are less evidence-based than many other disease states. Clinicians should be aware of the different treatments and recognize the best treatment for the individual. CONCLUSIONS The diagnosis and treatment of MG is a therapeutic challenge. Pharmacists play an essential role in the care of these patients by avoiding drugs that exacerbate the disease, promoting optimal pharmacotherapy, monitoring pharmacotherapy, and ensuring compliance with prescribed medications.
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Affiliation(s)
- Stephanie E Matney
- Virginia Commonwealth University/Medical College of Virginia, School of Pharmacy, Richmond, Virginia, USA
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Abstract
PURPOSE To investigate the clinical manifestations and ocular findings in children with ocular myasthenia gravis (MG) that rarely have been reported in the literature. DESIGN Retrospective, noncomparative case series. PARTICIPANTS Twenty-four consecutive patients less than 15 years of age with ocular MG treated between June 1988 and July 2001. METHODS The medical records of 6 boys and 18 girls with ocular MG were reviewed retrospectively. MAIN OUTCOME MEASURES Alternate prism cover and uncover test, examination of ductions and versions, and visual acuity. RESULTS Mean age at onset was 38 months. Ptosis was found in 23 patients (96%), strabismus in 21 patients (88%), and amblyopia in 5 patients (21%). Exotropia combined with vertical heterotropia was the most frequent type of strabismus. Ductions were limited in 17 patients (71%), among whom supraduction or infraduction limitations were most frequently observed. Contrary to previous reports, medial rectus underaction was less common than lateral rectus underaction. Manifestations of strabismus and limitation of duction were variable and changed frequently during the follow-up period. The combined use of prednisone and pyridostigmine was found to be the predominant form of maintenance therapy, and ptosis was more responsive to drug therapy than limited ocular motility. CONCLUSIONS Children with ocular MG were found to have a high incidence of ptosis (96%) and exotropia and vertical hyperdeviation. Limitation on adduction was less common than that on abduction. First reported incidence of amblyopia (21%) and a relative nonresponsiveness of the limitation of eye movement to treatment were also noted.
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Affiliation(s)
- Jong-Hyun Kim
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, South Korea
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Seronegative generalised myasthenia gravis: clinical features, antibodies, and their targets. Lancet Neurol 2003; 2:99-106. [PMID: 12849266 DOI: 10.1016/s1474-4422(03)00306-5] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myasthenia gravis (MG) is a well-recognised disorder of neuromuscular transmission that can be diagnosed by the presence of antibodies to the acetylcholine receptor (AChR). However, some patients (about 15%) with generalised MG do not have detectable AChR antibodies. There is some evidence, however, that this "seronegative" MG is an antibody-mediated disorder. Plasma from patients with the disorder seems to contain various distinct humoral factors: IgG antibodies that reversibly inhibit AChR function; a non-IgG (possibly IgM) factor that indirectly inhibits AChR function; and an IgG antibody against the muscle-specific kinase (MuSK). The presence of antibodies against MuSK appears to define a subgroup of patients with seronegative MG who have predominantly localised, in many cases bulbar, muscle weaknesses (face, tongue, pharynx, etc) and reduced response to conventional immunosuppressive treatments. Moreover, muscle wasting may be present, which prevents complete response to these therapies.
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Katz J, Barohn RJ. Update on the Evaluation and Therapy of Autoimmune Neuromuscular Junction Disorders. Phys Med Rehabil Clin N Am 2001. [DOI: 10.1016/s1047-9651(18)30076-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ellis FD, Hoyt CS, Ellis FJ, Jeffery AR, Sondhi N. Extraocular muscle responses to orbital cooling (ice test) for ocular myasthenia gravis diagnosis. J AAPOS 2000; 4:271-81. [PMID: 11040476 DOI: 10.1067/mpa.2000.106204] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND As a result of clinical and laboratory investigations of temperature correlates of myasthenia gravis, orbital cooling (ice test) has been developed as a reliable test for ocular myasthenia diagnosis through blepharoptosis response. The test has not been utilized in a prospective manner for myasthenia diagnosis through extraocular muscle responses. METHODS Fifteen patients with acquired motility disorders were studied with the use of orbital cooling and other tests for myasthenia gravis. Orbital cooling was performed in a standard fashion for all patients. In 14 of 15 patients, the diagnosis of myasthenia was not established at the time the ice test was performed. Fifteen non-myasthenic patients with acquired motility disorders were also studied with use of the ice test. Temperatures during orbital cooling were measured in the superior cul-de-sac of one patient and between the lateral rectus muscle and globe in 3 patients. RESULTS All patients subsequently proven to have myasthenia gravis by other tests and by response to myasthenia therapy had a positive (diagnostic of myasthenia) response to the ice test. No patient had a false-positive or a paradoxical response to the ice test. No control patient had a positive blepharoptosis or motility response to orbital cooling. Temperature measurements demonstrated significant cooling effects in the superotemporal cul-de-sac and beneath the lateral rectus muscles after orbital cooling for 5 minutes. CONCLUSIONS Orbital cooling, within certain parameters, can be a useful clinical test for myasthenia diagnosis through motility response, as well as blepharoptosis response.
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Affiliation(s)
- F D Ellis
- Midwest Eye Institute, Indianapolis, Indiana 46280, USA.
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Padua L, Stalberg E, LoMonaco M, Evoli A, Batocchi A, Tonali P. SFEMG in ocular myasthenia gravis diagnosis. Clin Neurophysiol 2000; 111:1203-7. [PMID: 10880794 DOI: 10.1016/s1388-2457(00)00307-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND AND OBJECTIVE In typical cases, the patient's history and clinical examination make it possible to diagnose ocular myasthenia gravis (OMG). But, in many cases a clear clinical picture is not present and OMG diagnosis is very difficult because gold diagnostic standard tests are not available. The diagnostic tests for OMG are usually unable to display a good sensitivity and specificity simultaneously. In this paper, we studied 86 cases submitted for suspected OMG. METHODS The patients were studied clinically and with various other tests used in OMG diagnosis (SFEMG, repetitive nerve stimulation, Ab anti AChR titration, tensilon test). RESULTS AND CONCLUSION SFEMG showed the highest sensitivity (100%) while Ab anti AChR showed the highest specificity (100%). To our knowledge this is the largest population of suspected OMG studied using most of the diagnostic parameters, reported in the literature.
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Affiliation(s)
- L Padua
- Department of Neurology, Università Cattolica, Rome, Italy.
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Abstract
We report a patient initially diagnosed as having ocular myasthenia gravis who showed progressive ophthalmoparesis and pseudoblepharospasm together with positive acetylcholine receptor antibodies. Repeated evaluation with high-frequency repetitive stimulation revealed an incremental response and elevated titers of antibodies against presynaptic calcium channels, confirming Lambert-Eaton myasthenic syndrome. Systemic evaluation revealed no malignant neoplasm but revealed euthyroid Hashimoto's disease. Immunomodulative therapy including plasma exchange and administration of an immunosuppressent (azathioprine) combined with a potassium-channel blocker (3,4-diaminopyridine) reduced the ocular abnormalities. We conclude that the ocular manifestations in this patient were probably caused by Lambert-Eaton myasthenic syndrome.
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Affiliation(s)
- N Kanzato
- Department of Neurology, National Okinawa Hospital, Ganeko 3-20-14, Ginowan-shi, Okinawa 901-2214, Japan
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Abstract
Ion channel defects produce a clinically diverse set of disorders that range from cystic fibrosis and some forms of migraine to renal tubular defects and episodic ataxias. This review discusses diseases related to impaired function of the skeletal muscle acetylcholine receptor and calcium channels of the motor nerve terminal. Myasthenia gravis is an autoimmune disease caused by antibodies directed toward the skeletal muscle acetylcholine receptor that compromise neuromuscular transmission. Congenital myasthenias are genetic disorders, a subset of which are caused by mutations of the acetylcholine receptor. Lambert-Eaton myasthenic syndrome is an immune disorder characterized by impaired synaptic vesicle release likely related to a defect of calcium influx. The disorders will illustrate new insights into synaptic transmission and ion channel structure that are relevant for all ion channel disorders.
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Affiliation(s)
- K Boonyapisit
- Department of Neurology, Case Western Reserve University School of Medicine, Department of Veterans Affairs Medical Center in Cleveland, University Hospitals of Cleveland, Ohio 44106, USA
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Abstract
Over the past 10 years, significant advances have been made in our understanding of acquired myasthenia gravis (MG) in companion animals. The broad spectrum of presenting clinical signs has been defined and an accurate and sensitive diagnostic test is available. Even with these advances, the mortality rate in dogs with acquired MG remains unacceptably high. While an understanding of the genetic basis for susceptibility to autoimmune disease has started to be developed, the trigger for the initiation of this disease is not known and a mechanism for specific suppression of the aberrant immune response against the acetylcholine receptor remains a mystery.
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Affiliation(s)
- G D Shelton
- Department of Pathology, University of California, San Diego, La Jolla 92093-0612, USA
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Abstract
This article discusses the assessment and management of rapidly progressive weakness due to neuromuscular disorders. The authors review elements helpful in determining the causes of weakness including pertinent history and laboratory studies. Disorders are classified according to the level of the motor unit involved and triage/management decisions are described. In addition, respiratory function assessment is reviewed. The latter part of this article is devoted to evaluation and management of two of the most common disorders, Guillain-Barré syndrome and myasthenia gravis.
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Affiliation(s)
- I Bella
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, USA
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29
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Abstract
All disorders of neuromuscular transmission (NMT) may cause ventilatory failure, albeit rarely. Respiratory muscle weakness is occasionally the presenting feature of myasthenia gravis (MG), the Lambert-Eaton myasthenic syndrome (LEMS), hypermagnesemia and botulism. Chronic MG, congenital myasthenic syndromes and LEMS may be acutely exacerbated by various intercurrent conditions and by drugs which interfere with NMT. Finally, in the ICU, difficulty in weaning from the ventilator may be caused by prolonged use of neuromuscular blocking agents. Electrophysiological studies of NMT disorders in the intensive care unit have rarely been reported. Nevertheless, the available data indicates that the electrodiagnosis of severe NMT disorders can be misleading. With severe NMT defects, the electrophysiological distinction between post-synaptic and pre-synaptic disorders is blurred and the differential diagnosis with myopathies may be difficult. A clinically suspected NMT disorder should therefore not be ruled out when electrodiagnosis fails to demonstrate the expected abnormalities.
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Affiliation(s)
- F Grand'Maison
- Service de Neurologie, Hôpital Charles-LeMoyne, Taschereau, Geenfield Park, Québec, Canada
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30
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Molekulare Pathogenese von Muskelerkrankungen. Naturwissenschaften 1996. [DOI: 10.1007/bf01141980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Abstract
Myasthenia gravis is an autoimmune disorder of neuromuscular transmission. It is characterised by muscular weakness and fatiguability. Extrinsic ocular muscles are frequently involved at the onset of the disease; in about 15% of cases clinical signs remain confined to these areas, while in the other patients weakness becomes generalised. Diagnosis relies on clinical history and signs, improvement on anticholinesterase injection, electromyographic signs of impaired neuromuscular transmission and serum antiacetylcholine receptor (anti-AChR) antibody titration. Apart from the anti-AChR antibody assay, no single test is specific for myasthenia gravis; it is rather their combined results that can confirm diagnosis. The therapeutic approach varies from patient to patient and, as far as possible, should be adapted to each individual. Symptomatic drugs such as anticholinesterases improve muscle strength but seldom restore it to normal. Immunosuppressive therapy is very effective but entails the risk of severe adverse effects. Thymectomy improves the course of the disease and can increase remission rate; short term treatments are of benefit in the management of myasthenic emergencies.
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Affiliation(s)
- A Evoli
- Institute of Neurology, Catholic University, Rome, Italy.
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Khan GA, Bank N. Interpretation of positive edrophonium (Tensilon) test in patients with end-stage renal disease. Ren Fail 1995; 17:65-71. [PMID: 7770646 DOI: 10.3109/08860229509036377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Many patients with end-stage renal disease (ESRD) have signs and symptoms of easy fatigability, fluctuating weakness, apathy, dry mouth, and blurring of vision. These symptoms can be confused with disorders of neuromuscular transmission. When present, the physician may want to determine whether the patient has myasthenia gravis--the commonest of all neuromuscular disorders--and administer the edrophonium (Tensilon) test. An unequivocally positive response to the test must be interpreted with caution in ESRD. However, the exact mechanism of a positive response is unclear but may be explained by metabolic abnormalities related to end-stage renal disease, i.e., uremic toxins, disordered calcium metabolism, abnormal neuromuscular mechanism, associated neurological disorders, or myopathic processes in uremia, all of which can affect neuromuscular transmission.
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Affiliation(s)
- G A Khan
- Department of Medicine, Montefiore Medical Center, University Hospital, Albert Einstein College of Medicine, Bronx, New York, USA
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34
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Barton JJ, Huaman AG, Sharpe JA. Effects of edrophonium on saccadic velocity in normal subjects and myasthenic and nonmyasthenic ocular palsies. Ann Neurol 1994; 36:585-94. [PMID: 7944291 DOI: 10.1002/ana.410360407] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We measured saccadic peak velocities in 8 patients with myasthenia gravis, 9 patients with proven nonmyasthenic ocular palsies, and 3 controls. Patients followed a target moving to and from primary position at 1-second intervals for 8 minutes. We measured the amplitudes and velocities of centrifugal saccades at the start of the task, after 3 minutes of the task (fatigue) and 1 minute after receiving IV edrophonium. The effects of fatigue, though prominent in some myasthenic patients, did not distinguish between the groups. However, edrophonium increased saccadic peak velocities in myasthenic patients but decreased them in both controls and nonmyasthenic patients. Analysis of saccades by amplitude bins showed that these changes in peak velocity reflected shifts in the velocity-amplitude relationship.
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Affiliation(s)
- J J Barton
- Neuro-ophthalmology Unit, Toronto Hospital Neurological Center, Ontario, Canada
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35
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36
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Oh SJ, Kim DE, Kuruoglu R, Bradley RJ, Dwyer D. Diagnostic sensitivity of the laboratory tests in myasthenia gravis. Muscle Nerve 1992; 15:720-4. [PMID: 1324429 DOI: 10.1002/mus.880150616] [Citation(s) in RCA: 142] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The diagnostic sensitivity of three laboratory tests [serum antiacetylcholine receptor antibody (AChR-ab) assay, the repetitive nerve stimulation (RNS) test, and, the single fiber EMG (SFEMG)] for myasthenia gravis (MG) was compared in 120 patients. In all cases, at least one of the tests was abnormal. SFEMG was the most sensitive test, being abnormal in 92% of cases, followed by the RNS test (77%) and the AChR-ab assay (73%). SFEMG was abnormal in all cases with negative AChR-ab and RNS tests, in 97% of cases with negative AChR-ab assay, in 89% of cases with negative RNS test, and in 89% of cases with mild MG. We conclude that one of these three tests is abnormal in all cases of MG, and that the SFEMG is most sensitive in the diagnosis of MG.
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Affiliation(s)
- S J Oh
- Department of Neurology, University of Alabama, Birmingham 35294
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Schwartzman MJ, Mitsumoto H, Shields RW, Estes ML, Meisler DM, Kosmorsky GS. Neurogenic muscle weakness in chronic progressive external ophthalmoplegia (CPEO). Muscle Nerve 1990; 13:1183-4. [PMID: 2266992 DOI: 10.1002/mus.880131214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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