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Yang XG, Guo HY, Peng Z, Luo HT, Lu S. Application of Electrophysiological Techniques in Assessing of Neuromuscular Junction-Related Disorders. World Neurosurg 2024; 191:165-171. [PMID: 39159673 DOI: 10.1016/j.wneu.2024.08.076] [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: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/21/2024]
Abstract
This review aims to comprehensively summarize the application of electrophysiological methods, specifically repetitive nerve stimulation (RNS) and single fiber electromyography (SFEMG), in the diagnosis of neuromuscular junction (NMJ) disorders, including myasthenia gravis, Lambert-Eaton syndrome, and sarcopenia in the elderly. Both RNS and SFEMG have demonstrated high sensitivity and specificity in detecting NMJ abnormalities. RNS aids in distinguishing presynaptic from postsynaptic lesions, while SFEMG provides direct evidence of NMJ function by assessing single motor unit action potentials. Key parameters in SFEMG, such as fiber density, jitter, and pulse blocking, are crucial for evaluating NMJ function. Increased fiber density and jitter value, along with pulse blocking, are often observed in patients with NMJ disorders. However, despite the extensive application of these techniques in various NMJ-related diseases, their role in aging, particularly in sarcopenic patients, remains underexplored, highlighting the need for future research.
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Affiliation(s)
- Xiong-Gang Yang
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Hong-Yang Guo
- Department of Rehabilitation, Affiliated Hospital of Hebei University of Technology, Handan, China
| | - Zhi Peng
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Hao-Tian Luo
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China
| | - Sheng Lu
- Department of Orthopedics, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming City, Yunnan Province, China; The Key Laboratory of Digital Orthopedics of Yunnan Province, Kunming City, Yunnan Province, China.
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Ahmed GK, Karim AA, Khedr EM, Elbeh K, Moheb A, Abokresha M, Haridy NA. Case report: Avoidant/restrictive food intake disorder after tonsillectomy. Front Psychiatry 2024; 15:1351056. [PMID: 38993387 PMCID: PMC11237393 DOI: 10.3389/fpsyt.2024.1351056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 05/29/2024] [Indexed: 07/13/2024] Open
Abstract
Background Avoidant Restrictive Food Intake Disorder (ARFID) is a newly classified eating disorder that requires further understanding of its presentation. There is no previous report of ARFID in a child post-tonsillectomy. ARFID may be a potential negative outcome for children following oropharyngeal surgery. Case presentation A female child aged 10 years and 2 months presented with ARFID associated with depression, anxiety and nutritional deficiency following tonsillectomy. She had more difficulty in swallowing solids than fluids and had repeated vomiting and spitting food after chewing it. She became dehydrated and malnourished with a BMI of 10.5 and was misdiagnosed with myasthenic gravis. Conclusions To our knowledge, this is the first case report of ARFID in a child post-tonsillectomy. We discuss the pathophysiology of ARFID, which remains elusive, and recommend psychiatric assessment when evaluating children post operative tonsillectomy.
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Affiliation(s)
- Gellan K. Ahmed
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Ahmed A. Karim
- Department of Psychiatry and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
| | - Eman M. Khedr
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Khaled Elbeh
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Amira Moheb
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Marwa Abokresha
- Department of Internal Medicine, Gastroenterology Unit, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Nourelhoda A. Haridy
- Department of Neurology and Psychiatry, Faculty of Medicine, Assiut University, Assiut, Egypt
- Department of Neuromuscular Disorders, University College London (UCL) Institute of Neurology, London, United Kingdom
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Valko Y, Wirth MA, Fierz FC, Schesny MK, Rosengren S, Schmückle-Meier T, Bockisch CJ, Straumann D, Schreiner B, Weber KP. Accuracy of Repetitive Ocular Vestibular-Evoked Myogenic Potentials to Diagnose Myasthenia Gravis in Patients With Ptosis or Diplopia. Neurology 2024; 102:e209395. [PMID: 38669629 PMCID: PMC11398977 DOI: 10.1212/wnl.0000000000209395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND AND OBJECTIVES We developed repetitive ocular vestibular-evoked myogenic potentials (roVEMP) as an electrophysiologic test that allows us to elicit the characteristic decrement of extraocular muscles in patients with ocular myasthenia gravis (OMG). Case-control studies demonstrated that roVEMP reliably differentiates patients with OMG from healthy controls. We now aimed to evaluate the diagnostic accuracy of roVEMP for OMG diagnosis in patients with ptosis and/or diplopia. METHODS In this blinded prospective diagnostic accuracy trial, we compared roVEMP in 89 consecutive patients presenting with ptosis and/or diplopia suspicious of OMG with a multimodal diagnostic approach, including clinical examination, antibodies, edrophonium testing, repetitive nerve stimulation of accessory and facial nerves, and single-fiber EMG (SFEMG). We calculated the roVEMP decrement as the ratio between the mean of the first 2 responses compared with the mean of the sixth-ninth responses in the train and used cutoff of >9% (unilateral decrement) in a 30 Hz stimulation paradigm. RESULTS Following a complete diagnostic work-up, 39 patients (44%) were diagnosed with ocular MG, while 50 patients (56%) had various other neuro-ophthalmologic conditions, but not MG (non-MG). roVEMP yielded 88.2% sensitivity, 30.2% specificity, 50% positive predictive value (PPV), and 76.5% negative predictive value (NPV). For comparison, SFEMG resulted in 75% sensitivity, 56% specificity, 55.1% PPV, and 75.7% NPV. All other diagnostic tests (except for the ice pack test) also yielded significantly higher positive results in patients with MG compared with non-MG. DISCUSSION The study revealed a high sensitivity of 88.2% for roVEMP in OMG, but specificity and PPV were too low to allow for the OMG diagnosis as a single test. Thus, differentiating ocular MG from other neuro-ophthalmologic conditions remains challenging, and the highest diagnostic accuracy is still obtained by a multimodal approach. In this study, roVEMP can complement the diagnostic armamentarium for the diagnosis of MG. CLASSIFICATION OF EVIDENCE This study provides Class I evidence that in patients with diplopia and ptosis, roVEMP alone does not accurately distinguish MG from non-MG disorders. TRIAL REGISTRATION INFORMATION ClinicalTrials.gov: NCT03049956.
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Affiliation(s)
- Yulia Valko
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Magdalena A Wirth
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Fabienne C Fierz
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Marianne K Schesny
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Sally Rosengren
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Tanja Schmückle-Meier
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Christopher J Bockisch
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Dominik Straumann
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Bettina Schreiner
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
| | - Konrad P Weber
- From the Neurology Department (Y.V., M.K.S., C.J.B., D.S., B.S., K.P.W.), Clinical Neuroscience Center, and Ophthalmology Department (M.A.W., F.C.F., T.S.-M., C.J.B., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Neurology Department and Institute of Clinical Neurosciences (S.R.), Royal Prince Alfred Hospital, Camperdown; and Central Clinical School (S.R.), Faculty of Medicine and Health, University of Sydney, Australia
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Dziadkowiak E, Baczyńska D, Waliszewska-Prosół M. MuSK Myasthenia Gravis-Potential Pathomechanisms and Treatment Directed against Specific Targets. Cells 2024; 13:556. [PMID: 38534400 DOI: 10.3390/cells13060556] [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: 02/13/2024] [Revised: 03/17/2024] [Accepted: 03/19/2024] [Indexed: 03/28/2024] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease in which autoantibodies target structures within the neuromuscular junction, affecting neuromuscular transmission. Muscle-specific tyrosine kinase receptor-associated MG (MuSK-MG) is a rare, often more severe, subtype of the disease with different pathogenesis and specific clinical features. It is characterized by a more severe clinical course, more frequent complications, and often inadequate response to treatment. Here, we review the current state of knowledge about potential pathomechanisms of the MuSK-MG and their therapeutic implications as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of myasthenia gravis.
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Affiliation(s)
- Edyta Dziadkowiak
- Department of Neurology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland
| | - Dagmara Baczyńska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland
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Kouyoumdjian JA, Estephan EDP. Electrophysiological evaluation of the neuromuscular junction: a brief review. ARQUIVOS DE NEURO-PSIQUIATRIA 2023; 81:1040-1052. [PMID: 38157872 PMCID: PMC10756823 DOI: 10.1055/s-0043-1777749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
The nerve terminal and muscle membrane compose the neuromuscular junction. After opening the voltage-gated calcium channels, action potentials from the motor axons provoke a cascade for the acetylcholine release from synaptic vesicles to the synaptic cleft, where it binds to its receptor at the muscle membrane for depolarization. Low amplitude compound muscle action potential typically presents in presynaptic disorders, increasing by more than 100% after a 10-second effort in the Lambert-Eaton myasthenic syndrome and less in botulism. Needle electromyography may show myopathic motor unit action potentials and morphological instability ("jiggle") due to impulse blocking. Low-frequency repetitive nerve stimulation (RNS) is helpful in postsynaptic disorders, such as myasthenia gravis and most congenital myasthenic syndromes, where the number of functioning acetylcholine receptors is reduced. Low-frequency RNS with a decrement >10% is abnormal when comparing the 4th to the first compound muscle action potential amplitude. High-frequency RNS is helpful in presynaptic disorders like Lambert-Eaton myasthenic syndrome, botulism, and some rare congenital myasthenic syndromes. The high-frequency RNS releases more calcium, increasing the acetylcholine with a compound muscle action potential increment. Concentric needle records apparent single-fiber action potentials (spikes). A voluntary activation measures the jitter between spikes from two endplates. An electrical activation measures the jitter of one spike (one endplate). The jitter is the most sensitive test for detecting a neuromuscular junction dysfunction. Most neuromuscular junction disorders are responsive to treatment.
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Affiliation(s)
- João Aris Kouyoumdjian
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
| | - Eduardo de Paula Estephan
- Faculdade de Medicina de São José do Rio Preto, Departamento de Ciências Neurológicas, Psiquiatria e Psicologia Médica, São José do Rio Preto SP, Brazil.
- Universidade de São Paulo, Departamento de Neurologia, São Paulo SP, Brazil.
- Faculdade de Medicina Santa Marcelina, São Paulo SP, Brazil.
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Clifford KM, Wu CK, Post D, Shaik R, Muppidi S. Utility of Repetitive Nerve Stimulation in the Diagnosis of Myasthenia Gravis in the Inpatient Setting. Neurohospitalist 2023; 13:364-370. [PMID: 37701254 PMCID: PMC10494823 DOI: 10.1177/19418744231173829] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023] Open
Abstract
Objectives Sensitivity and specificity of Repetitive Nerve Stimulation (RNS) is typically reported from outpatient centers, and we hypothesized that these values might not apply to hospitalized patients with higher grades of weakness. RNS may be helpful in rapidly confirming diagnosis of myasthenia gravis (MG) in the inpatient setting, as results from confirmatory antibody testing are often delayed. We sought to characterize the sensitivity and specificity of RNS in the inpatient setting to assist in the early diagnosis of MG. Methods We performed a retrospective analysis of all adult patients who had inpatient RNS at our center from 2016 to 2021. Inclusion criteria included RNS performed at least at one site and a neurological evaluation which prompted an electrodiagnostic study to evaluate for neuromuscular junction (NMJ) pathology. Descriptive statistics and Fisher exact analysis were performed. Results Of the 32 identified hospitalized patients, 6 had greater than 10% decrement on slow RNS, confirming NMJ dysfunction. Five were diagnosed with MG, and 1 with Lambert-Eaton myasthenic syndrome. Of the 26 patients with normal RNS, 25 ultimately had alternative causes of weakness. One was later diagnosed as seronegative MG based on clinical improvement with acetylcholinesterase inhibitors. In our inpatient population, the overall sensitivity and specificity of RNS were 83.3% and 96.2% respectively. There was a statistically significant association between a positive RNS and diagnosis of MG (P = .0002). Conclusions RNS is a highly sensitive and specific test for the diagnosis of MG in an inpatient setting, and these results are likely more rapidly available compared to antibody testing.
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Affiliation(s)
- Katherine M Clifford
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA
| | - Connie K Wu
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA
| | - David Post
- Advocate Aurora Health, Park Ridge, IL, USA
| | - Ruba Shaik
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA
| | - Srikanth Muppidi
- Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA
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Bocci T, Bertini A, Campiglio L, Botta S, Libelli G, Guidetti M, Priori A. Not myopathic, but autonomic changes in patients with long-COVID syndrome: a case series. Neurol Sci 2023; 44:1147-1153. [PMID: 36735149 PMCID: PMC9896447 DOI: 10.1007/s10072-023-06637-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 01/20/2023] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Neurological sequelae following SARS-CoV-2 infection still represent a serious concern both for neurologists and neuroscientists. In our paper, we investigated pain, myalgia, and fatigue as symptoms in long-COVID patients with an electrophysiological approach, comprising the evaluation of sympathetic skin responses (SSRs) and quantitative electromyography (qEMG). MATERIALS AND METHODS Twelve patients were enrolled (mean age, 47.7 ± 11.6 years), referred to our attention because of myalgia, pain, or muscle cramps, which persisted about 6 months after the diagnosis of SARS-CoV-2 infection. They underwent conventional electroneurography (ENG), needle electromyography (EMG), and SSRs; moreover, qEMG was performed by sampling at least 20 motor unit potentials (20-30 MUPs) during weak voluntary contraction in deltoid and tibialis anterior muscles. The mean duration, amplitude, and percentage of polyphasic potentials were assessed and compared with healthy and age-matched volunteers. RESULTS ENG did not disclose significant changes compared to healthy subjects; needle EMG did not reveal denervation activity. In addition, qEMG showed MUPs similar to those recorded in healthy volunteers in terms of polyphasia (deltoid: p = 0.24; TA: p = 0.35), MUP area (deltoid: p = 0.45; TA: p = 0.44), mean duration (deltoid: p = 0.06; TA: p = 0.45), and amplitude (deltoid: p = 0.27; TA: p = 0.63). SSRs were not recordable from lower limbs in seven patients (58%) and from the upper ones in three of them (25%). CONCLUSION Our data suggest an involvement of the autonomic system, with a focus on cholinergic efferent sympathetic activity, without any evidence of myopathic changes.
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Affiliation(s)
- Tommaso Bocci
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20142, Milan, Italy.
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20100, Milano, Italy.
- Clinical Neurology Unit, "Azienda Socio-Sanitaria Territoriale Santi Paolo E Carlo" and Department of Health Sciences, University of Milan, Via Antonio Di Rudinì 8, 20142, Milan, Italy.
| | - Alessandro Bertini
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20142, Milan, Italy
- Clinical Neurology Unit, "Azienda Socio-Sanitaria Territoriale Santi Paolo E Carlo" and Department of Health Sciences, University of Milan, Via Antonio Di Rudinì 8, 20142, Milan, Italy
| | - Laura Campiglio
- Clinical Neurology Unit, "Azienda Socio-Sanitaria Territoriale Santi Paolo E Carlo" and Department of Health Sciences, University of Milan, Via Antonio Di Rudinì 8, 20142, Milan, Italy
| | - Stefano Botta
- Clinical Neurology Unit, "Azienda Socio-Sanitaria Territoriale Santi Paolo E Carlo" and Department of Health Sciences, University of Milan, Via Antonio Di Rudinì 8, 20142, Milan, Italy
| | - Giorgia Libelli
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20142, Milan, Italy
- Department of Medicine and Surgery, Neurology Unit, University of Parma, Via Gramsci 14, 43126, Parma, Italy
| | - Matteo Guidetti
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20142, Milan, Italy
- Department of Electronics, Information and Bioengineering, Politecnico Di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy
| | - Alberto Priori
- ''Aldo Ravelli'' Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, Via Antonio di Rudinì 8, 20142, Milan, Italy
- Clinical Neurology Unit, "Azienda Socio-Sanitaria Territoriale Santi Paolo E Carlo" and Department of Health Sciences, University of Milan, Via Antonio Di Rudinì 8, 20142, Milan, Italy
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Bedside and laboratory diagnostic testing in myasthenia. J Neurol 2022; 269:3372-3384. [PMID: 35142871 PMCID: PMC9119875 DOI: 10.1007/s00415-022-10986-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/02/2022]
Abstract
Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are a group of disorders with a well characterised autoimmune or genetic and neurophysiological basis. We reviewed the literature from the last 20 years assessing the utility of various neurophysiological, immunological, provocative and genetic tests in MG and CMS. Diagnostic sensitivity of repetitive nerve stimulation test ranges between 14 and 94% and specificity between 73 and 100%; sensitivity of single-fibre EMG (SFEMG) test ranges between 64 and 100% and specificity between 22 and 100%; anti-acetylcholine receptor (AChR) antibody sensitivity ranges from 13 to 97% and specificity ranges from 95 to 100%. Overall, SFEMG has the highest sensitivity while positive anti-AChR antibodies have the highest specificity. Newer testing strategies that have been investigated over the last couple of decades include ocular vestibular-evoked myogenic potentials, otoacoustic emissions and disease-specific circulating miRNAs in serum for autoimmune myasthenia, as well as next-generation sequencing for genetic testing of CMS. While there has been significant progress in developing newer testing strategies for diagnosing MG and CMS over the last couple of decades, more research is needed to assess the utility of these newer tools regarding their sensitivity and specificity.
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Katzberg HD, Abraham A. Electrodiagnostic Assessment of Neuromuscular Junction Disorders. Neurol Clin 2021; 39:1051-1070. [PMID: 34602214 DOI: 10.1016/j.ncl.2021.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Please verify edits, "These techniques", or specify. This article reviews advanced electrodiagnostic techniques used to assess for neuromuscular junction disorders, including repetitive nerve stimulation, conventional or concentric-needle single-fiber electromyography (SFEMG), and stimulated SFEMG. These techniques have high sensitivity but limited specificity. Novel methods currently under investigation are discussed, including vestibular ocular myogenic potential and oculography analysis.
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Affiliation(s)
- Hans D Katzberg
- Division of Neurology, University Health Network, Toronto General Hospital, 200 Elizabeth Street, 5ES-306, Toronto, Ontario M5G 2C4, Canada.
| | - Alon Abraham
- Neuromuscular Diseases Unit, Department of Neurology, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv 6423906, Israel
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Lamb CJ, Rubin DI. Sensitivity and specificity of repetitive nerve stimulation with lower cutoffs for abnormal decrement in myasthenia gravis. Muscle Nerve 2020; 62:381-385. [PMID: 32530515 DOI: 10.1002/mus.26999] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/04/2020] [Accepted: 06/07/2020] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The sensitivity of repetitive nerve stimulation (RNS) in myasthenia gravis (MG) is dependent on the cutoff for abnormal decrement. METHODS RNS data of adults with and without MG from 2014 to 2017 were reviewed retrospectively. The maximum reliable RNS amplitude/area decrement before and after exercise from facial, spinal accessory (SA), ulnar, and fibular nerves was recorded. Sensitivity/specificity using 5%, 7%, and 10% cutoffs were calculated. RESULTS Seventy-nine of 141 patients had MG (46 generalized, 21 ocular, 12 bulbar). A total of 608 unique RNS recordings were analyzed. Overall RNS sensitivity/specificity at ≥5%, ≥7%, and ≥10% amplitude cutoffs were as follows: SA, 65.6%/86.3%, 49.2%/94.1%, and 29.5%/96.1%; facial, 51.0%/82.5%, 43.1%/95.0%, and 37.3%/100%; ulnar, 43.6%/100%, 41.0%/100%, and 41.0%/100%; and fibular, 52.6%/89.5%, 42.1%/94.7%, and 42.1%/100%. DISCUSSION Lowering amplitude cutoff from 10% to 7% increased or maintained sensitivity with little loss in specificity. Post-exercise and area analysis resulted in increased sensitivity in some circumstances.
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Affiliation(s)
| | - Devon I Rubin
- Department of Neurology, Mayo Clinic, Jacksonville, Florida, USA
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Occipitalis muscle: using for repetitive facial nerve stimulation in myasthenia gravis. Acta Neurol Belg 2020; 120:609-613. [PMID: 29428994 DOI: 10.1007/s13760-018-0889-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 01/25/2018] [Indexed: 10/18/2022]
Abstract
Repetitive nerve stimulation (RNS) is a highly sensitive electrophysiological test used for diagnosing myasthenia gravis (MG). Here, we evaluated electrodiagnostic value of RNS using facial nerve and occipitalis muscle. Patients with generalized MG were included. Clinical findings were assessed. RNS test was performed on occipitalis, nasalis, trapezius, abductor policis brevis (APB) and abductor digiti minimi (ADM) muscles. Twenty-five (78%) patients had relevant decrement during RNS test of at least one muscle. Nasalis muscle had the highest diagnostic potential (68.8%), followed by trapezius (53.3%), occipitalis (50%), APB (30%) and ADM (16.7%) muscles. There was not a significant relationship between clinical symptoms and facial RNS recorded on occipitalis muscle. In conclusion, we suggest that facial RNS recording over occipitalis muscle can be added in electrodiagnosis of MG because of cranial nerve innervation and proximal location. Facial RNS recording over occipitalis muscle provides a good choice under the conditions such as atrophy, cosmetic surgery, or botulinum toxin application in which nasalis muscle is unavailable for use.
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Abstract
PURPOSE OF REVIEW Myasthenia gravis (MG) is an autoimmune neuromuscular disease that causes fluctuating weakness in ocular, bulbar, and limb muscles and can, in 15% of cases, cause myasthenic crisis, a neurologic emergency characterized by respiratory failure. Although infrequent, MG needs to be promptly recognized and treated because the potential for improvement and remission is very high. The diagnosis of MG can be challenging and delayed because of the fluctuating nature of muscle weakness and the overlap of signs and symptoms with other neuromuscular diseases.This article reviews the importance of prompt recognition of the typical signs and symptoms, best tests to confirm the diagnosis, currently available acute and chronic treatment modalities, the role of thymectomy, and the natural history of the disease. Special consideration related to the diagnosis and management in women during pregnancy and in children will also be reviewed. This article also includes an overview of congenital myasthenic syndromes. RECENT FINDINGS Recent significant efforts in standardizing and improving the care of patients with MG have occurred, as well as new momentum in developing new drugs for patients with MG who do not adequately respond to currently available treatments. The number of clinical trials and drugs in development for MG is steadily increasing. Eculizumab has been recently approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive, based on the REGAIN (Safety and Efficacy of Eculizumab in Refractory Generalized Myasthenia Gravis) study, a phase 3, randomized, double-blind, placebo-controlled, multicenter trial. An international, multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone has demonstrated that thymectomy improves clinical outcome in patients with nonthymomatous MG. Clinical care guidelines have been published, and the recommendations for clinical research standards and the Myasthenia Gravis Foundation of America MGFA clinical classification published in 2000 have become widely accepted by the clinical and research community of MG experts. SUMMARY MG is a highly treatable disease with many effective treatment modalities available and with a natural history that continues to improve thanks to better diagnostic tests and effective drugs. The diagnosis and management of patients affected by MG can be highly rewarding for any neurologist as most patients are able to live normal lives if treated appropriately. Nevertheless, future research is needed to address unresolved clinical issues, such as when and how to discontinue immunosuppressive medications in patients in remission, the role and timing of thymectomy in children, and better treatment options for refractory patients.
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Stålberg E, van Dijk H, Falck B, Kimura J, Neuwirth C, Pitt M, Podnar S, Rubin DI, Rutkove S, Sanders DB, Sonoo M, Tankisi H, Zwarts M. Standards for quantification of EMG and neurography. Clin Neurophysiol 2019; 130:1688-1729. [DOI: 10.1016/j.clinph.2019.05.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 12/11/2022]
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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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Baseline Decrement in Patients with Mild Myasthenia Gravis Predicts Immunomodulation Treatment. Can J Neurol Sci 2019; 46:762-766. [PMID: 31322098 DOI: 10.1017/cjn.2019.246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To explore whether higher degrees of electrophysiological abnormalities are associated with a more frequent exposure to a more aggressive treatment regimen, we performed a retrospective chart review of patients attending the neuromuscular clinic from June 2012 to December 2015 and included 87 patients. We compared treatment regimens during the follow-up period between patients with high and low jitter and decrement. Myasthenia gravis patients with high jitter or decrement at baseline were more frequently treated with intravenous immunoglobulins (IVIG) and/or plasma exchange (PLEX) during the follow-up period. In patients with mild disease, IVIG or PLEX treatment was associated with high decrement.
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Schwartz L, Lafitte O, da Veiga Moreira J. Toward a Reasoned Classification of Diseases Using Physico-Chemical Based Phenotypes. Front Physiol 2018. [PMID: 29541031 PMCID: PMC5835834 DOI: 10.3389/fphys.2018.00094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: Diseases and health conditions have been classified according to anatomical site, etiological, and clinical criteria. Physico-chemical mechanisms underlying the biology of diseases, such as the flow of energy through cells and tissues, have been often overlooked in classification systems. Objective: We propose a conceptual framework toward the development of an energy-oriented classification of diseases, based on the principles of physical chemistry. Methods: A review of literature on the physical chemistry of biological interactions in a number of diseases is traced from the point of view of the fluid and solid mechanics, electricity, and chemistry. Results: We found consistent evidence in literature of decreased and/or increased physical and chemical forces intertwined with biological processes of numerous diseases, which allowed the identification of mechanical, electric and chemical phenotypes of diseases. Discussion: Biological mechanisms of diseases need to be evaluated and integrated into more comprehensive theories that should account with principles of physics and chemistry. A hypothetical model is proposed relating the natural history of diseases to mechanical stress, electric field, and chemical equilibria (ATP) changes. The present perspective toward an innovative disease classification may improve drug-repurposing strategies in the future.
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Affiliation(s)
| | - Olivier Lafitte
- LAGA, UMR 7539, Paris 13 University, Sorbonne Paris Cité, Villetaneuse, France
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Palpebral portion of the orbicularis oculi muscle to repetitive nerve stimulation testing: A potential assessment indicator in patients with generalized myasthenia gravis. J Clin Neurosci 2017; 48:238-242. [PMID: 29239825 DOI: 10.1016/j.jocn.2017.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 11/15/2017] [Indexed: 11/20/2022]
Abstract
Repetitive nerve stimulation (RNS) is a valuable diagnostic method for myasthenia gravis (MG). However, its association with clinical severity was scarcely studied. We reviewed medical records and retrospectively enrolled 121 generalized MG patients. Sensitivity of different muscles to RNS and clinical scoring systems was evaluated. RNS testing revealed facial muscles have the highest positive rate, followed by proximal muscles and distal muscles, with the palpebral portion of the orbicularis oculi muscle most sensitive. Amplitude decrement of compound muscle action potential (CMAP) in the palpebral portion of the orbicularis oculi muscle is related to quantitative myasthenia gravis (QMG) scores, MG-specific manual muscle testing (MMT) scores and myasthenia gravis-related activities of daily living (MG-ADL) scores. We suggest that RNS testing of the palpebral portion of the orbicularis oculi muscle is a potential assessment indicator in patients with generalized MG.
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Recording Fewer Than 20 Potential Pairs With SFEMG May Suffice for the Diagnosis of Myasthenia Gravis. J Clin Neurophysiol 2017. [DOI: 10.1097/wnp.0000000000000402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Diagnostic Utility of Repetitive Nerve Stimulation in a Large Cohort of Patients With Myasthenia Gravis. J Clin Neurophysiol 2017; 34:400-407. [DOI: 10.1097/wnp.0000000000000398] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Diagnostic tests for myasthenia gravis: Comments on statistical method. J Neurol Sci 2017; 379:337. [DOI: 10.1016/j.jns.2017.05.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 05/22/2017] [Indexed: 11/19/2022]
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Abraham A, Breiner A, Barnett C, Katzberg HD, Bril V. The utility of a single simple question in the evaluation of patients with myasthenia gravis. Muscle Nerve 2017; 57:240-244. [DOI: 10.1002/mus.25720] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/29/2017] [Accepted: 06/04/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Alon Abraham
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network; University of Toronto, General Hospital; Room 5 EB 309, 200 Elizabeth Street, Toronto Ontario M5G 2C4 Canada
| | - Ari Breiner
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network; University of Toronto, General Hospital; Room 5 EB 309, 200 Elizabeth Street, Toronto Ontario M5G 2C4 Canada
| | - Carolina Barnett
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network; University of Toronto, General Hospital; Room 5 EB 309, 200 Elizabeth Street, Toronto Ontario M5G 2C4 Canada
| | - Hans D. Katzberg
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network; University of Toronto, General Hospital; Room 5 EB 309, 200 Elizabeth Street, Toronto Ontario M5G 2C4 Canada
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network; University of Toronto, General Hospital; Room 5 EB 309, 200 Elizabeth Street, Toronto Ontario M5G 2C4 Canada
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Hinge-deleted IgG4 blocker therapy for acetylcholine receptor myasthenia gravis in rhesus monkeys. Sci Rep 2017; 7:992. [PMID: 28428630 PMCID: PMC5430546 DOI: 10.1038/s41598-017-01019-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 03/28/2017] [Indexed: 11/08/2022] Open
Abstract
Autoantibodies against ion channels are the cause of numerous neurologic autoimmune disorders. Frequently, such pathogenic autoantibodies have a restricted epitope-specificity. In such cases, competing antibody formats devoid of pathogenic effector functions (blocker antibodies) have the potential to treat disease by displacing autoantibodies from their target. Here, we have used a model of the neuromuscular autoimmune disease myasthenia gravis in rhesus monkeys (Macaca mulatta) to test the therapeutic potential of a new blocker antibody: MG was induced by passive transfer of pathogenic acetylcholine receptor-specific monoclonal antibody IgG1-637. The effect of the blocker antibody (IgG4Δhinge-637, the hinge-deleted IgG4 version of IgG1-637) was assessed using decrement measurements and single-fiber electromyography. Three daily doses of 1.7 mg/kg IgG1-637 (cumulative dose 5 mg/kg) induced impairment of neuromuscular transmission, as demonstrated by significantly increased jitter, synaptic transmission failures (blockings) and a decrease in the amplitude of the compound muscle action potentials during repeated stimulations (decrement), without showing overt symptoms of muscle weakness. Treatment with three daily doses of 10 mg/kg IgG4Δhinge-637 significantly reduced the IgG1-637-induced increase in jitter, blockings and decrement. Together, these results represent proof-of principle data for therapy of acetylcholine receptor-myasthenia gravis with a monovalent antibody format that blocks binding of pathogenic autoantibodies.
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Abraham A, Breiner A, Barnett C, Katzberg HD, Lovblom LE, Rt MN, Bril V. Electrophysiological testing is correlated with myasthenia gravis severity. Muscle Nerve 2017; 56:445-448. [PMID: 28029691 DOI: 10.1002/mus.25539] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/07/2016] [Accepted: 12/24/2016] [Indexed: 11/06/2022]
Abstract
INTRODUCTION Electrophysiological studies play an important role in the diagnosis of myasthenia gravis (MG). The objectives of this study was to explore the correlation of jitter and decrement with various clinical symptoms and signs and disease severity. METHODS We performed a retrospective chart review of 75 MG patients who attended the neuromuscular clinic from April 2013 to May 2014. We compared clinical characteristics between patients with high jitter (>100 µs) and decrement (>10%), and patients with lower values to explore the correlations and optimal thresholds of jitter and decrement for different clinical features. RESULTS High jitter and decrement values were associated with more severe disease, manifested by more frequent symptomatic bulbar and limb muscle weakness, more frequent ocular and limb muscle weakness on examination, higher quantitative MG score, and generalized disease. CONCLUSIONS The yield of the electrophysiological assessment in MG extends beyond disease diagnosis and correlates with disease severity and the presence of generalized disease. Muscle Nerve 56: 445-448, 2017.
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Affiliation(s)
- Alon Abraham
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
| | - Ari Breiner
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
| | - Carolina Barnett
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
| | - Hans D Katzberg
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
| | - Leif E Lovblom
- Division of Endocrinology and Metabolism, Department of Medicine, Mount Sinai, Hospital and Lunenfeld Tanenbaum Research Institute, University of Toronto, Toronto, Canada
| | - Mylan Ngo Rt
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital, 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada, M5G 2C4
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