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Malanda A, Stashuk DW, Navallas J, Rodríguez-Falces J, Rodríguez-Carreño I, Valle C, Garnés-Camarena O. Automatic jitter measurement in needle-detected motor unit potential trains. Comput Biol Med 2022; 149:105973. [DOI: 10.1016/j.compbiomed.2022.105973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 07/28/2022] [Accepted: 08/13/2022] [Indexed: 11/03/2022]
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Sanders DB, Kouyoumdjian JA, Stålberg EV. Single fiber electromyography and measuring jitter with concentric needle electrodes. Muscle Nerve 2022; 66:118-130. [PMID: 35694863 DOI: 10.1002/mus.27573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 05/06/2022] [Indexed: 11/07/2022]
Abstract
This monograph contains descriptions of the single fiber electromyography (SFEMG) method and of the more recently implemented method of recording jitter with concentric needle electrodes (CNEs). SFEMG records action potentials from single muscle fibers (SFAPs), which permits measuring fiber density (FD), a sensitive measure of reinnervation, and jitter, a sensitive measure of abnormal neuromuscular transmission (NMT). With voluntary activation, jitter is measured between two SFAPs with acceptable amplitude and rise time. With activation by axon stimulation, jitter is measured between the stimulus and individual SFAPs. Pitfalls due to unstable triggers and inconstant firing rates during voluntary activation and subliminal stimulation during axon stimulation should be identified and avoided. In CNE recordings, spikes with shoulders or rising phases that are not parallel are produced by summation of SFAPS; these should be excluded and reference values for CNE jitter should be used. CNE and SFEMG have similar and very high sensitivity in detecting increased jitter, as in myasthenia gravis and other myasthenic conditions. However, jitter is also seen in ongoing reinnervation and some myopathic conditions. With SFEMG, these can be identified by increased FD; however, FD cannot be measured with CNE, and conventional electromyography should be performed in muscles with increased jitter to detect neurogenic or myogenic abnormalities. Jitter is abnormal after injections of botulinum toxin, even in muscles remote from the injection site, and can persist for 6 mo or more. This can complicate the detection or exclusion of abnormal NMT.
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Affiliation(s)
- Donald B Sanders
- Department of Neurology, Duke University Medical Center, Durham, North Carolina, USA
| | - João A Kouyoumdjian
- Department of Neurological Sciences, State Medical School (FAMERP), São Paulo, Brazil
| | - Erik V Stålberg
- Department of Clinical Neurophysiology, Academic Hospital, Uppsala, Sweden
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Sanders DB, Kouyoumdjian JA, Stålberg EV. Single fiber EMG and measuring jitter with concentric needle electrodes. Muscle Nerve 2022. [PMID: 35652573 DOI: 10.1002/mus.27572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 05/05/2022] [Indexed: 11/08/2022]
Abstract
This monograph contains descriptions of the single-fiber electromyography (SFEMG) method and of the more recently implemented method of recording jitter with concentric needle electrodes (CNE). SFEMG records action potentials from single muscle fibers (SFAPs), which permits measuring fiber density (FD), a sensitive measure of reinnervation, and jitter, a sensitive measure of abnormal neuromuscular transmission (NMT). With voluntary activation, jitter is measured between two SFAPs with acceptable amplitude and rise time. With activation by axon stimulation, jitter is measured between the stimulus and individual SFAPs. Pitfalls due to unstable triggers and inconstant firing rates during voluntary activation and subliminal stimulation during axon stimulation should be identified and avoided. In CNE recordings, spikes with shoulders or rising phases that are not parallel are produced by summation of SFAPS; these should be excluded and reference values for CNE jitter should be used. CNE and SFEMG have similar and very high sensitivity in detecting increased jitter, as in myasthenia gravis and other myasthenic conditions. However, jitter is also seen in ongoing reinnervation and some myopathic conditions. With SFEMG, these can be identified by increased FD; however, FD cannot be measured with CNE, and conventional EMG should be performed in muscles with increased jitter to detect neurogenic or myogenic abnormalities. Jitter is abnormal after injections of botulinum toxin, even in muscles remote from the injection site, and can persist for 6 mo or more. This can complicate the detection or exclusion of abnormal NMT.
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Affiliation(s)
- Donald B Sanders
- Department of Neurology, Duke University Medical Center, Durham, North Carolina, USA
| | - João A Kouyoumdjian
- Department of Neurological Sciences, State Medical School (FAMERP), São Paulo, Brazil
| | - Erik V Stålberg
- Department of Clinical Neurophysiology, Academic Hospital, Uppsala, Sweden
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McHugh JC, O'Flaherty E, Daly N. Does specificity of electrodiagnostic test referrals predict for test outcome in children? Muscle Nerve 2022; 65:513-520. [PMID: 35119698 DOI: 10.1002/mus.27515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 01/26/2022] [Accepted: 01/29/2022] [Indexed: 11/08/2022]
Abstract
INTRODUCTION/AIMS Electrodiagnostic testing (EDX) is important in evaluation of pediatric neuromuscular disease. Non-specific referrals have emerged as a leading reason for EDX in recent years. We examine whether referral-specificity is predictive of test outcomes in children. METHODS EDX referrals and outcomes were audited over a 7-year period from 2013 to 2020 at CHI-Crumlin. Pre-test details were coded and compared to EDX outcomes using multinomial logistic regression. RESULTS EDX studies were performed in 702 children (median age 10.2 yrs). In 36% of patients, EDX-referrals did not specify any pre-test diagnosis. Mononeuropathy (24%) and polyneuropathy (15%) were the leading pre-specified diagnoses as well as the most common test outcomes. Neurology and orthopedics/plastic surgery contributed the majority of referrals. Metabolic medicine and hematology/oncology were most likely to pre-specify a working diagnosis and were the specialties with both the highest proportion of abnormal outcomes and referral accuracy. EDX abnormality was present in 42% of patients and was predicted by specificity of referral and the absence of pain as a leading symptom. The accuracy of specified pre-test diagnoses was highest for suspected anterior horn cell disorders (67%). Accuracy of referrals, as well as abnormal test outcomes, were negatively predicted by the presence of pain as a leading symptom. DISCUSSION EDX is informative in children but the likelihood of abnormal test-outcomes is diminished when a pre-specified working diagnosis is lacking or when the primary reason for referral is pain. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- John C McHugh
- Department of Clinical Neurophysiology, Children's Health Ireland (CHI)-Crumlin Crumlin, Dublin, Ireland
| | - Eileen O'Flaherty
- Department of Clinical Neurophysiology, Children's Health Ireland (CHI)-Crumlin Crumlin, Dublin, Ireland
| | - Nicole Daly
- Department of Clinical Neurophysiology, Children's Health Ireland (CHI)-Crumlin Crumlin, Dublin, Ireland
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Caldas VM, Heise CO, Kouyoumdjian JA, Zambon AA, Silva AMS, Estephan EDP, Zanoteli E. Electrophysiological study of neuromuscular junction in congenital myasthenic syndromes, congenital myopathies, and chronic progressive external ophthalmoplegia. Neuromuscul Disord 2020; 30:897-903. [PMID: 33121830 DOI: 10.1016/j.nmd.2020.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 11/19/2022]
Abstract
This study was designed to analyze the sensitivity, specificity, and accuracy of jitter parameters combined with repetitive nerve stimulation (RNS) in congenital myasthenic syndrome (CMS), chronic progressive external ophthalmoplegia (CPEO), and congenital myopathies (CM). Jitter was obtained with a concentric needle electrode during voluntary activation of the Orbicularis Oculi muscle in CMS (n = 21), CPEO (n = 20), and CM (n = 18) patients and in controls (n = 14). RNS (3 Hz) was performed in six different muscles for all patients (Abductor Digiti Minimi, Tibialis Anterior, upper Trapezius, Deltoideus, Orbicularis Oculi, and Nasalis). RNS was abnormal in 90.5% of CMS patients and in only one CM patient. Jitter was abnormal in 95.2% of CMS, 20% of CPEO, and 11.1% of CM patients. No patient with CPEO or CM presented a mean jitter higher than 53.6 µs or more than 30% abnormal individual jitter (> 45 µs). No patient with CPEO or CM and mild abnormal jitter values presented an abnormal decrement. Jitter and RNS assessment are valuable tools for diagnosing neuromuscular transmission abnormalities in CMS patients. A mean jitter value above 53.6 µs or the presence of more than 30% abnormal individual jitter (> 45 µs) strongly suggests CMS compared with CPEO and CM.
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Affiliation(s)
- Vitor Marques Caldas
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - Carlos Otto Heise
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - João Aris Kouyoumdjian
- Laboratório de Investigação Neuromuscular, Faculdade Estadual de Medicina de São Jose do Rio Preto (FAMERP), São Jose do Rio Preto, SP, Brazil
| | - Antônio Alberto Zambon
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - André Macedo Serafim Silva
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - Eduardo de Paula Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil; Department of Medicine, Faculdade Santa Marcelina, São Paulo, Brazil
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil.
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O'Connell K, Ramdas S, Palace J. Management of Juvenile Myasthenia Gravis. Front Neurol 2020; 11:743. [PMID: 32793107 PMCID: PMC7393473 DOI: 10.3389/fneur.2020.00743] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Juvenile Myasthenia Gravis (JMG) is a rare disorder, defined as myasthenia gravis in children younger than 18 years of age. While clinical phenotypes are similar to adults, there are a number of caveats that influence management: broader differential diagnoses; higher rates of spontaneous remission; and the need to initiate appropriate treatment early, to avoid the long-term physical and psychosocial morbidity. Current practice is taken from treatment guidelines for adult MG or individual experience, with considerable variability seen across centers. We discuss our approach to treating JMG, in a large specialist JMG service, and review currently available evidence and highlight potential areas for future research. First-line treatment of generalized JMG is symptomatic management with pyridostigmine, but early use of immunosuppression, where good control is not achieved is important. Oral prednisolone is used as first-line immunosuppression with appropriate prevention and monitoring of side effects. Second-line therapies including azathioprine and mycophenolate may be considered where there is: no response to steroids, inability to wean to a reasonable minimum effective dose or if side-effects are intolerable. Management of ocular JMG is similar, but requires close involvement of ophthalmology in young children to prevent amblyopia. Muscle-specific tyrosine kinase (MuSK)-JMG show a poorer response to pyridostigmine and anecdotal evidence suggests that rituximab should be considered as second-line immunosuppression. Thymectomy is indicated in any patient with a thymoma, and consideration should be given in acetylcholine receptor (AChR) positive JMG allowing time for spontaneous remission. The benefit is less clear in ocular JMG and is not advised in MuSK-JMG. Children experiencing a myasthenic crisis require urgent hospital admission with access to the intensive care unit. PLEX is preferred over IVIG due to rapid onset of action, but this needs to be balanced with feasibility in very young children. Key questions remain in the management of JMG: when to initiate both first- and second-line treatments, choosing between steroid-sparing agents, and determining the optimal dose and treatment duration. We feel that given the rarity of this disease, the establishment of national registries and collaboration across groups will be needed to address these issues and facilitate future drug trials in JMG.
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Affiliation(s)
- Karen O'Connell
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Sithara Ramdas
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
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Kang PB, McMillan HJ, Kuntz NL, Lehky TJ, Alter KE, Fitzpatrick KF, El Kosseifi C, Quijano-Roy S. Utility and practice of electrodiagnostic testing in the pediatric population: An AANEM consensus statement. Muscle Nerve 2020; 61:143-155. [PMID: 31724199 DOI: 10.1002/mus.26752] [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: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/17/2022]
Abstract
Nerve conduction studies and needle electromyography, collectively known as electrodiagnostic (EDX) studies, have been available for pediatric patients for decades, but the accessibility of this diagnostic modality and the approach to testing vary significantly depending on the physician and institution. The maturation of molecular diagnostic approaches and other diagnostic technologies such as neuromuscular ultrasound indicate that an analysis of current needs and practices for EDX studies in the pediatric population is warranted. The American Association of Neuromuscular & Electrodiagnostic Medicine convened a consensus panel to perform literature searches, share collective experiences, and develop a consensus statement. The panel found that electrodiagnostic studies continue to have high utility for the diagnosis of numerous childhood neuromuscular disorders, and that standardized approaches along with the use of high-quality reference values are important to maximize the diagnostic yield of these tests in infants, children, and adolescents.
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Affiliation(s)
- Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida.,Department of Neurology, University of Florida College of Medicine, Gainesville, Florida
| | - Hugh J McMillan
- Department of Pediatrics, University of Ottawa and Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Nancy L Kuntz
- Department of Pediatrics, Northwestern University Feinberg School of Medicine and Lurie Children's Hospital, Chicago, Illinois
| | - Tanya J Lehky
- National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
| | - Katharine E Alter
- Functional and Applied Biomechanics Section, Rehabilitation Medicine, National Institutes of Health Clinical Center, Bethesda, Maryland
| | - Kevin F Fitzpatrick
- Inova Neuroscience and Spine Institute, Inova Fairfax Hospital, Falls Church, Virginia
| | - Charbel El Kosseifi
- Centre de Référence Maladies Neuromusculaires, Service de Neurologie, Réanimation et Réeducation Pédiatriques, Hôpital Raymond Poincaré, Garches, France
| | - Susana Quijano-Roy
- Centre de Référence Maladies Neuromusculaires, Service de Neurologie, Réanimation et Réeducation Pédiatriques, Hôpital Raymond Poincaré, Garches, France
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Hirasawa-Inoue A, Ishiyama A, Takeshita E, Shimizu-Motohashi Y, Saito T, Komaki H, Nakagawa E, Yuasa S, Saitsu H, Hamanaka K, Miyatake S, Matsumoto N, Sasaki M. Single-fiber electromyography-based diagnosis of CACNA1A mutation in children: A potential role of the electrodiagnosis in the era of whole exome sequencing. Brain Dev 2019; 41:905-909. [PMID: 31288946 DOI: 10.1016/j.braindev.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 06/20/2019] [Accepted: 06/25/2019] [Indexed: 10/26/2022]
Abstract
INTRODUCTION A loss-of-function mutation in CACNA1A, which encodes P/Q-type Ca channels, causes various diseases. As most of the Ca channels at neuromuscular junctions are of the P/Q type, patients with loss-of-function CACNA1A mutations exhibit disturbed neuromuscular transmission. The associated jitters and blocking in such patients can be detected by single-fiber electromyography (SFEMG). CASES We report two cases with different phenotypes, which were predicted to harbor loss-of-function mutations of CACNA1A, by using axonal stimulation SFEMG. One case involved a 2-year-old boy with episodic ataxia type 2. The other case involved a 7-year-old girl diagnosed with epileptic encephalopathy. SFEMG results revealed jitters and blocking in both cases. Moreover, whole exome sequencing (WES) revealed a heterozygous CACNA1A mutation, c.5251C>T, p.Arg1751Trp, in the former case and a novel de novo CACNA1A mutation, c.2122G>A, p.Val708Met, in the latter. CONCLUSIONS Our cases indicate that SFEMG is a potentially useful diagnostic tool for patients with CACNA1A mutation, especially in pediatric cases where trio analysis is difficult or novel mutations are present.
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Affiliation(s)
- Ayaka Hirasawa-Inoue
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Akihiko Ishiyama
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan.
| | - Eri Takeshita
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Yuko Shimizu-Motohashi
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Takashi Saito
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Hirofumi Komaki
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Eiji Nakagawa
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
| | - Shota Yuasa
- Department of Pediatrics, Kameda Medical Center, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Japan
| | - Kohei Hamanaka
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Masayuki Sasaki
- Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Japan
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ECEL1 gene related contractural syndrome: Long-term follow-up and update on clinical and pathological aspects. Neuromuscul Disord 2018; 28:741-749. [PMID: 30131190 DOI: 10.1016/j.nmd.2018.05.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 05/21/2018] [Accepted: 05/29/2018] [Indexed: 12/14/2022]
Abstract
Autosomal recessive mutations in the ECEL1 gene have recently been associated with a wide phenotypic spectrum including severe congenital contractural syndromes and distal arthrogryposis type 5D (DA5D). Here, we describe four novel families with ECEL1 gene mutations, reporting 15 years of follow-up for four patients and detailed muscle pathological description for three individuals. In particular, we observed mild myopathic features, prominent core-like areas in one individual, and presence of nCAM positive fibres in three patients from 2 unrelated families suggesting a possible problem with innervation. Our findings expand current knowledge concerning the phenotypic and pathological spectrum associated with ECEL1 gene mutations and may suggest novel insights regarding the underlying pathomechanism of the disease.
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Neurophysiological Assessment of Abnormalities of the Neuromuscular Junction in Children. Int J Mol Sci 2018; 19:ijms19020624. [PMID: 29470437 PMCID: PMC5855846 DOI: 10.3390/ijms19020624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 01/16/2018] [Accepted: 01/17/2018] [Indexed: 11/16/2022] Open
Abstract
The function of the neuromuscular junction in children is amenable to electrophysiological testing. Of the two tests available, repetitive nerve stimulation is uncomfortable and has a reduced sensitivity compared with single-fibre methodology. The latter is the method of choice, recording the variability in neuromuscular transmission as a value called jitter. It can be performed by voluntary activation of the muscle being examined, which is not suitable in children, or by stimulation techniques. A modification of these techniques, called Stimulated Potential Analysis with Concentric needle Electrodes (SPACE), is well tolerated and can be performed while the child is awake. It has a high sensitivity (84%) for the diagnosis of neuromuscular transmission disorders, the majority of which are myasthenic syndromes, and a moderate specificity (70%). The latter can be improved by the exclusion of neurogenic causes and the determination of the degree of jitter abnormality. Minor jitter abnormalities, under 115% of the upper limit of normal, are usually caused by myopathies with an associated neuromuscular transmission disorder, whereas levels higher than this value are usually associated with one of the myasthenic conditions.
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11
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Pitt MC. Use of stimulated electromyography in the analysis of the neuromuscular junction in children. Muscle Nerve 2017; 56:841-847. [DOI: 10.1002/mus.25685] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/18/2017] [Accepted: 05/01/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Matthew C. Pitt
- Department of Clinical NeurophysiologyGreat Ormond Street Hospital for Children NHS Foundation TrustGreat Ormond Street, LondonWC1N 3JH United Kingdom
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