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Rigamonti A, Mantero V, Scaioli V, Mauri E, Salmaggi A. Repetitive nerve stimulation and single-fibre electromyography: a biomarker of response to eculizumab in refractory myasthenia gravis? Neurol Sci 2024:10.1007/s10072-024-07663-w. [PMID: 38926246 DOI: 10.1007/s10072-024-07663-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 06/20/2024] [Indexed: 06/28/2024]
Affiliation(s)
- Andrea Rigamonti
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy.
| | - Vittorio Mantero
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
| | - Vidmer Scaioli
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
| | - Eliana Mauri
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
| | - Andrea Salmaggi
- Neurology Unit, Ospedale A. Manzoni, ASST Lecco, Via Dell'Eremo 9-11, 23900, Lecco, Italy
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The diagnostic and prognostic utility of repetitive nerve stimulation in patients with myasthenia gravis. Sci Rep 2023; 13:2985. [PMID: 36806815 PMCID: PMC9941475 DOI: 10.1038/s41598-023-30154-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Repetitive nerve stimulation (RNS) is a standard test for the diagnosis of myasthenia gravis (MG), where decrement of compound muscle action potentials (CMAP) corresponds to clinical muscle fatigability. Our aim was to ascertain the diagnostic and prognostic utility of RNS in MG patients. This study included MG patients treated between 01/2000 and 12/2016, with an observational period of at least one year and a minimum of two neurological examinations. Clinical and electrophysiological data were retrospectively gathered from patient records, and CMAP decrement was correlated with autoantibody titers and clinical disease severity at different time points. Ninety-four patients were included, with 88.3% of the cohort testing positive for acetylcholine receptor autoantibodies (AChR-Abs). RNS sensitivity was higher in patients with generalized disease (71.6%) than in purely ocular MG (38.5%). CMAP decrement did not significantly correlate with AChR-Ab titers, nor with clinical symptom severity at the time of testing or last follow up. However, there was a significant correlation between CMAP decrement and the worst recorded clinical status on a group level. RNS testing is more sensitive in generalized disease and AChR-Ab positive patients, but our data do not support RNS as a tool for long-term outcome prediction. Future studies with a prospective study design could help to overcome a number of limiting factors discussed in our study.
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Khoo A, Hay Mar H, Borghi MV, Catania S. Electrophysiologic evaluation of myasthenia gravis and its mimics: real-world experience with single-fiber electromyography. Hosp Pract (1995) 2022; 50:373-378. [PMID: 36103994 DOI: 10.1080/21548331.2022.2125706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVES In centers which routinely perform single fiber electromyography (SFEMG) for suspected myasthenia gravis (MG), the additional benefit of other neurophysiologic investigations and the frequency of myasthenia mimics has not been ascertained. We aimed to illustrate the range of neurological and non-neurological myasthenia mimics referred for evaluation, and contrast features of their electrophysiologic evaluation with confirmed MG. METHODS We reviewed all SFEMG studies performed at our center between 1 January 2018 and 31 December 2020. Patient demographics, clinical phenotype, antibody status and final diagnosis were recorded. Electrophysiologic findings were correlated with clinical features and sensitivity analyses performed. RESULTS A total of 528 SFEMG studies were performed, of which 213 (41%) were abnormal. A diagnosis of MG was made in 101 individuals, including 46 with ocular MG and 35 with seronegative disease. Compared to myasthenia mimics with an abnormal SFEMG, individuals with MG had higher median jitter (mean consecutive difference 61 μs vs. 42 μs, p < 0.001) and a greater percentage of abnormal pairs (61% vs. 33%, p < 0.001) on SFEMG. Repetitive nerve stimulation was abnormal in 27.1% of people with MG and was associated with a generalized clinical phenotype (OR 4.17; 95% CI 1.67-10.48). Thirteen (2%) individuals with MG had normal SFEMG, of whom 10 were in clinical remission. Functional neurological disorders, cranial nerve palsies, primary ocular disease and myopathy were frequent myasthenia mimics. CONCLUSION SFEMG can be abnormal in a number of myasthenia mimics, and routine nerve conduction studies and electromyography should always be undertaken. In centers where SFEMG is performed routinely for the investigation of suspected MG, extensive proximal repetitive nerve stimulation can be foregone without substantially affecting diagnostic evaluation. Normal SFEMG in those with confirmed myasthenia gravis may help indicate clinical remission.
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Affiliation(s)
- Anthony Khoo
- Department of Neurology, National Hospital for Neurology and Neurosurgery, London, UK
- Faculty of Brain Sciences, UCL Queen Square Institute of Neurology, London, UK
- Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
- College of Medicine and Public Health, Flinders University, South Australia, Australia
| | - Hnin Hay Mar
- Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Maria Victoria Borghi
- Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Santiago Catania
- Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
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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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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: 5] [Impact Index Per Article: 2.5] [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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Sanders DB, Raja SM, Guptill JT, Hobson‐Webb LD, Juel VC, Massey JM. The
D
uke myasthenia gravis clinic registry:
I
.
D
escription and demographics. Muscle Nerve 2020; 63:209-216. [DOI: 10.1002/mus.27120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/22/2022]
Affiliation(s)
- Donald B. Sanders
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
| | - Shruti M. Raja
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
| | - Jeffrey T. Guptill
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
| | - Lisa D. Hobson‐Webb
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
| | - Vern C. Juel
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
| | - Janice M. Massey
- Neuromuscular Division, Department of Neurology Duke University Medical Center Durham North Carolina USA
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Sanders DB, Arimura K, Cui L, Ertaş M, Farrugia ME, Gilchrist J, Kouyoumdjian JA, Padua L, Pitt M, Stålberg E. Guidelines for single fiber EMG. Clin Neurophysiol 2019; 130:1417-1439. [PMID: 31080019 DOI: 10.1016/j.clinph.2019.04.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/30/2019] [Accepted: 04/06/2019] [Indexed: 12/13/2022]
Abstract
This document is the consensus of international experts on the current status of Single Fiber EMG (SFEMG) and the measurement of neuromuscular jitter with concentric needle electrodes (CNE - CN-jitter). The panel of authors was chosen based on their particular interests and previous publications within a specific area of SFEMG or CN-jitter. Each member of the panel was asked to submit a section on their particular area of interest and these submissions were circulated among the panel members for edits and comments. This process continued until a consensus was reached. Donald Sanders and Erik Stålberg then edited the final document.
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Affiliation(s)
| | - Kimiyoshi Arimura
- Department of Neurology and Geriatrics, Kagoshima University, Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
| | - LiYing Cui
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
| | | | | | - James Gilchrist
- Southern Illinois University School of Medicine, Springfield, IL USA.
| | | | - Luca Padua
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Department of Geriatrics, Neurosciences and Orthopaedics, Università Cattolica del Sacro Cuore, Rome, Italy.
| | - Matthew Pitt
- Department of Clinical Neurophysiology, Great Ormond Street Hospital, London, UK.
| | - Erik Stålberg
- Department of Clinical Neurophysiology, Uppsala University, Uppsala, Sweden.
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What is in the Neuromuscular Junction Literature? J Clin Neuromuscul Dis 2018; 20:76-84. [PMID: 30439753 DOI: 10.1097/cnd.0000000000000218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This update begins with myasthenia gravis and the roles of anti-agrin and cortactin antibodies. Regarding diagnosis, a report on repeated ice pack testing is highlighted as are several reports on the close correlation of electrodiagnostic testing with clinical features and the response to treatment. The incidence of head drop and associated clinical and ventilatory features are gleaned from a retrospective study. We also discuss a study that assessed the predominantly symmetric and conjugate ocular findings in MuSK-myasthenia gravis. Other topics that are covered include quality of life and preoperative risk. We then summarize the positive treatment trials of subcutaneous immunoglobulin and eculizumab. Turning to Lambert-Eaton Myasthenic Syndrome, we report on an epidemiologic study performed on the veteran affairs population, the results of the DAPPER study of 3, 4 diaminopyridine, and look to the future for other treatment options involving calcium gating modifiers.
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Bhatia S, Quinlan H, McCracken C, Price EW, Guglani L, Verma S. Serial Stimulated Jitter Analysis In Juvenile Myasthenia Gravis. Muscle Nerve 2018; 58:729-732. [DOI: 10.1002/mus.26319] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/27/2018] [Accepted: 08/05/2018] [Indexed: 11/08/2022]
Affiliation(s)
| | - Haley Quinlan
- Department of Rehabilitation and Therapy Services; Children's Healthcare of Atlanta; Atlanta Georgia USA
| | - Courtney McCracken
- Division of Biostatistics, Department of Pediatrics; Emory University School of Medicine; Atlanta Georgia USA
| | - Eric W. Price
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Department of Pediatrics; Emory University School of Medicine; Atlanta Georgia USA
| | - Lokesh Guglani
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep, Department of Pediatrics; Emory University School of Medicine; Atlanta Georgia USA
| | - Sumit Verma
- Division of Pediatric Neurology, Department of Pediatrics; Emory University School of Medicine, Atlanta, 1605 Chantilly Drive NE, Suite 300; Atlanta Georgia 30324 USA
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Husain AM. Ellen Grass Memorial Lecture: Clinical Neurophysiology in the Treatment of Disease. Neurodiagn J 2018; 58:203-212. [PMID: 31307328 DOI: 10.1080/21646821.2018.1539598] [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: 10/27/2022]
Abstract
Clinical neurophysiology has a long-standing history and value in the diagnosis of neurologic diseases. Because of their unique ability to assess physiology and function of the nervous system, electroencephalography (EEG), evoked potentials, electromyography (EMG), and polysomnography have long been used in the diagnostic evaluation of epilepsies, demyelinating disorders, neuromuscular disorders, sleep disorders, and other diseases affecting the central and peripheral nervous systems. The role of these tests and clinical neurophysiology in general has usually ended upon diagnosis. New applications of these trusted techniques are changing old perceptions. Continuous EEG monitoring has found new value in not only diagnosis but also in treatment of nonconvulsive seizures and status epilepticus. Visual evoked potentials have been shown to be a biomarker for assessment of demyelination and remyelination associated with treatment of multiple sclerosis. Various EMG techniques can be used to independently assess improvement or otherwise of many neuromuscular diseases. The use of these techniques in the treatment of various neurologic disorders is the next frontier for clinical neurophysiology.
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Affiliation(s)
- Aatif M Husain
- a Department of Neurology , Duke University Medical Center , Durham , North Carolina.,b Neuroscience Medicine , Duke Clinical Research Institute , Durham , North Carolina.,c Neurodiagnostic Center , Veterans Affairs Medical Center , Durham , North Carolina
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