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Jacob S. Treating myasthenia gravis beyond the eye clinic. Eye (Lond) 2024:10.1038/s41433-024-03133-x. [PMID: 38789789 DOI: 10.1038/s41433-024-03133-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/17/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Myasthenia gravis (MG) is one of the most well characterised autoimmune disorders affecting the neuromuscular junction with autoantibodies targeting the acetylcholine receptor (AChR) complex. The vast majority of patients present with ocular symptoms including double vision and ptosis, but may progress on to develop generalised fatiguable muscle weakness. Severe involvement of the bulbar muscles can lead to dysphagia, dysarthria and breathing difficulties which can progress to myasthenic crisis needing ventilatory support. Given the predominant ocular onset of the disease, it is important that ophthalmologists are aware of the differential diagnosis, investigations and management including evolving therapies. When the disease remains localised to the extraocular muscles (ocular MG) IgG1 and IgG3 antibodies against the AChR (including clustered AChR) are present in nearly 50% of patients. In generalised MG this is seen in nearly 90% patients. Other antibodies include those against muscle specific tyrosine kinase (MuSK) and lipoprotein receptor related protein 4 (LRP4). Even though decremental response on repetitive nerve stimulation is the most well recognised neurophysiological abnormality, single fibre electromyogram (SFEMG) in experienced hands is the most sensitive test which helps in the diagnosis. Initial treatment should be using cholinesterase inhibitors and then proceeding to immunosuppression using corticosteroids and steroid sparing drugs. Patients requiring bulbar muscle support may need rescue therapies including plasma exchange and intravenous immunoglobulin (IVIg). Newer therapeutic targets include those against the B lymphocytes, complement system, neonatal Fc receptors (FcRn) and various other elements of the immune system.
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Affiliation(s)
- Saiju Jacob
- University Hospitals Birmingham, Birmingham, UK.
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.
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Bilgin Topçuoğlu Ö, Çetintaş Afşar G, Alibaş H, Uluç K. Impact of obstructive sleep apnea on neuromuscular transmission- a descriptive study. Cranio 2024; 42:292-297. [PMID: 34228607 DOI: 10.1080/08869634.2021.1952016] [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] [Indexed: 10/20/2022]
Abstract
Objective: Obstructive sleep apnea (OSA) is a sleep disorder accompanied by intermittent hypoxia. Neuromuscular transmission (NT) is known to be disturbed under chronic hypoxia. In this descriptive study, it has been aimed to test NT under intermittent hypoxia in OSA. Methods: Thirty-nine newly diagnosed OSA patients without any comorbidities or conditions that alter NT were included in the study. Jitter analysis was performed using a concentric needle electrode. Results: The mean jitter value of 39 OSA patients was 25.9 ± 3.7 μs. When compared to the mean reference jitter values, patients in the present study had significantly higher jitter (p < 0.001). Seven (17.9%) patients met the electrophysiological criteria for NT failure. Conclusion: The authors propose that intermittent hypoxia can be the trigger for NT failure in OSA. The interaction between increased oxidative stress and disturbed mitochondrial functions may also contribute.
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Affiliation(s)
| | - Gülgün Çetintaş Afşar
- Department of Chest Diseases, Sureyyapasa Chest Diseases and Thorax Surgery Training and Research Hospital, Istanbul, Turkey
| | - Hande Alibaş
- Department of Neurology, Marmara University, Medical School, Istanbul, Turkey
| | - Kayıhan Uluç
- Department of Neurology, Marmara University, Medical School, Istanbul, Turkey
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Harrison P, Barton J, Winkel A. Chronic mimics of myasthenia gravis: a retrospective case series. Neuromuscul Disord 2023; 33:250-256. [PMID: 36753801 DOI: 10.1016/j.nmd.2023.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 01/29/2023]
Abstract
Myasthenia gravis often presents a diagnostic challenge and may be misdiagnosed, particularly in seronegative disease with active symptoms. We retrospectively evaluated 61 patients following the introduction of single fibre electromyography at our service, and identified 8 mimics which had been inappropriately diagnosed and treated as refractory myasthenia gravis. 6 of these were seronegative, but two had positive acetylcholine receptor (AChR) antibodies. The final diagnoses included one case each of chronic progressive external ophthalmoplegia, chronic ptosis, oculopharyngeal muscular dystrophy, and an undifferentiated disorder suspicious for either a mitochondrial cytopathy or low-grade myositis. Four were diagnosed with functional neurological disorder, one of which had a superimposed thyroid myopathy and orbitopathy. We found the average duration of misdiagnosis was 9 years (SD±5.2, median 11 years), and patients were often exposed to years of unnecessary treatment. All patients had received anticholinesterase therapy, three had immunotherapy, and three surgical interventions were performed including two thymectomies. We found myasthenic mimics should be suspected in disease that is static and treatment refractory, and functional mimics in disease with frequent flares. Thorough neurophysiologic assessment is important, particularly when making a diagnosis of seronegative myasthenia gravis.
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Affiliation(s)
- Patrick Harrison
- Neurology Department, Sunshine Coast University Hospital, 6 Doherty St, Birtinya Qld 4575, Australia; Griffith University, School of Medicine, Australia.
| | - Joshua Barton
- Neurology Department, Sunshine Coast University Hospital, 6 Doherty St, Birtinya Qld 4575, Australia
| | - Antony Winkel
- Neurology Department, Sunshine Coast University Hospital, 6 Doherty St, Birtinya Qld 4575, Australia; Griffith University, School of Medicine, Australia
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Sandberg A. Motor unit properties do not correlate between MUNIX and needle EMG in remote polio in the biceps brachii muscle. Clin Neurophysiol Pract 2022; 8:24-31. [PMID: 36632370 PMCID: PMC9826944 DOI: 10.1016/j.cnp.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 12/07/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Objective To compare the utility of MUNIX (motor unit number index) with needle EMG in characterizing motor unit (MU) properties in the biceps brachii (BB) muscle in subjects with remote polio. Methods Thirty subjects suffering from remote polio were investigated with MUNIX and needle EMG, all with Macro EMG and 16 of these subjects with concentric needle EMG. Results Both MUNIX and the needle EMG methods showed abnormal results. Fiber density (FD) was the most sensitive parameter for showing signs of reinnervation. At a group level, the methods showed neurogenic findings, but there was no correlation between the results of the MUNIX and needle EMG investigations. Conclusions Both MUNIX and needle EMG are valuable methods for measuring neurogenic involvement in the BB muscle. However, there was a lack of correlation between the MUNIX and needle EMG findings. The cause for this missing correlation may be multifactorial as there are several differences between the methods. Significance The reason for the lack of correlation between the MUNIX and needle EMG results is discussed. By combining the needle and surface recorded methods one can obtain more information on the denervation and reinnervation process compared to using just one of the methods alone.
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Hehir MK, Li Y. Diagnosis and Management of Myasthenia Gravis. Continuum (Minneap Minn) 2022; 28:1615-1642. [PMID: 36537972 DOI: 10.1212/con.0000000000001161] [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: 12/24/2022]
Abstract
PURPOSE OF REVIEW This article reviews updated diagnostic procedures and currently available treatment modalities for myasthenia gravis (MG). RECENT FINDINGS Patients with MG can be classified based on antibody status and their clinical presentation; treatment responses may differ based on disease subtypes. Improved diagnostic methods and recognition of new antigenic targets such as lipoprotein-related protein 4 have led to improved diagnostic efficiencies. Corticosteroids remain the first-line immunotherapy, but there is a trend toward minimizing their use at high doses and for long durations. Oral immunosuppressants such as mycophenolate mofetil, azathioprine, and tacrolimus remain useful. An international, multicenter randomized trial comparing thymectomy plus prednisone with prednisone alone demonstrated that thymectomy improves clinical outcomes in selected patients with nonthymomatous MG. Eculizumab, efgartigimod, and ravulizumab have recently been approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive. These drugs take advantage of novel mechanisms of action and expand treatment options for patients with MG. Data on rituximab suggest that it can be a good option, especially for patients with MG who are positive for antibodies against muscle-specific tyrosine kinase (MuSK). The number of clinical trials and drugs in development for MG is steadily increasing. SUMMARY The diagnosis of MG can generally be made from the patient's history, a neurologic examination, and laboratory and electrodiagnostic testing. Carefully selected treatment improves outcomes in MG. Additional treatment options for MG will likely be available in the near future.
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Fisher G, Mackels L, Markati T, Sarkozy A, Ochala J, Jungbluth H, Ramdas S, Servais L. Early clinical and pre-clinical therapy development in Nemaline myopathy. Expert Opin Ther Targets 2022; 26:853-867. [PMID: 36524401 DOI: 10.1080/14728222.2022.2157258] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Nemaline myopathies (NM) represent a group of clinically and genetically heterogeneous congenital muscle disorders with the common denominator of nemaline rods on muscle biopsy. NEB and ACTA1 are the most common causative genes. Currently, available treatments are supportive. AREAS COVERED We explored experimental treatments for NM, identifying at least eleven mainly pre-clinical approaches utilizing murine and/or human muscle cells. These approaches target either i) the causative gene or associated genes implicated in the same pathway; ii) pathophysiologically relevant biochemical mechanisms such as calcium/myosin regulation of muscle contraction; iii) myogenesis; iv) other therapies that improve or optimize muscle function more generally; v) and/or combinations of the above. The scope and efficiency of these attempts is diverse, ranging from gene-specific effects to those widely applicable to all NM-associated genes. EXPERT OPINION The wide range of experimental therapies currently under consideration for NM is promising. Potential translation into clinical use requires consideration of additional factors such as the potential muscle type specificity as well as the possibility of gene expression remodeling. Challenges in clinical translation include the rarity and heterogeneity of genotypes, phenotypes, and disease trajectories, as well as the lack of longitudinal natural history data and validated outcomes and biomarkers.
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Affiliation(s)
- Gemma Fisher
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK
| | - Laurane Mackels
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Neuromuscular Reference Center, University and University Hospital of Liège, Liège, Belgium
| | - Theodora Markati
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK
| | - Anna Sarkozy
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Hospital, Institute of Child Health, London, UK
| | - Julien Ochala
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Heinz Jungbluth
- Department of Paediatric Neurology - Neuromuscular Service, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK.,Randall Centre for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College London, London, UK
| | - Sithara Ramdas
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK
| | - Laurent Servais
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Neuromuscular Reference Center, University and University Hospital of Liège, Liège, Belgium
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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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Sirin T, Karaaslan Z, Arkali B, Bekdik P, Akinci T, Candan F, Akarsu E, Baslo MB, Orhan E, Oge AE. Is Video-Oculography a Predictive Test for Myasthenia Gravis with Ocular Symptoms? Neurol India 2022; 70:80-86. [DOI: 10.4103/0028-3886.336330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Kirk EA, Zero AM, Rice CL. Firing rate trajectories of human occipitofrontalis motor units in response to triangular voluntary contraction intensity. Exp Brain Res 2021; 239:3661-3670. [PMID: 34617127 DOI: 10.1007/s00221-021-06238-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/26/2021] [Indexed: 12/01/2022]
Abstract
During voluntary contractions, limb muscle motor unit (MU) firing rates accelerate over a small force range and saturate in response to increasing contraction intensity. In comparison, facial muscles are cranially innervated, and some function without crossing joints. Therefore, the MU firing rate behaviour and characteristics of saturation were explored in a facial muscle that moves skin and facia during voluntary contractions. We evaluated the firing rate trajectory in response to triangular voluntary contraction ramps in the occipitofrontalis muscle of 11 adult participants. Intramuscular electromyography of the frontalis aspect was used to record single MU trains followed up to maximal voluntary contraction intensities. Firing rates were measured from each MU sample, with the firing rate trajectory fit as both exponential (i.e., saturation) and linear models that were compared statistically. The rate coding behaviour of frontalis MUs was broad, as the peak firing rate (mean 76 Hz) was ninefold greater than the firing rate at recruitment threshold (mean 8 Hz). Across 20 MU samples, only 40% (8 MU samples) were determined to have a firing rate trajectory that saturated and had slow acceleration in response to increasing voluntary drive until maximum. The exponential curve of the firing rate trajectory had ~ tenfold lower acceleration as compared to prior reports in limb muscles. These results across all MU samples indicated that voluntary control of the frontalis muscle requires relatively slower accelerating or linear MU firing rate trajectories, suggesting that movements of facial muscles may be directly representative of extrinsic synaptic inputs.
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Affiliation(s)
- Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada
| | - Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, Western University, London, Canada. .,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, Canada.
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Moron H, Gagnard-Landra C, Guiraud D, Dupeyron A. Contribution of Single-Fiber Evaluation on Monitoring Outcomes Following Injection of Botulinum Toxin-A: A Narrative Review of the Literature. Toxins (Basel) 2021; 13:toxins13050356. [PMID: 34067540 PMCID: PMC8156529 DOI: 10.3390/toxins13050356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022] Open
Abstract
Botulinum toxin-A (BoNT-A) blocks acetylcholine release at the neuromuscular junction (NMJ) and is widely used for neuromuscular disorders (involuntary spasms, dystonic disorders and spasticity). However, its therapeutic effects are usually measured by clinical scales of questionable validity. Single-fiber electromyography (SFEMG) is a sensitive, validated diagnostic technique for NMJ impairment such as myasthenia. The jitter parameter (µs) represents the variability of interpotential intervals of two muscle fibers from the same motor unit. This narrative review reports SFEMG use in BoNT-A treatment. Twenty-four articles were selected from 175 eligible articles searched in Medline/Pubmed and Cochrane Library from their creation until May 2020. The results showed that jitter is sensitive to early NMJ modifications following BoNT-A injection, with an increase in the early days’ post-injection and a peak between Day 15 and 30, when symptoms diminish or disappear. The reappearance of symptoms accompanies a tendency for a decrease in jitter, but always precedes its normalization, either delayed or nonexistent. Increased jitter is observed in distant muscles from the injection site. No dose effect relationship was demonstrated. SFEMG could help physicians in their therapeutic evaluation according to the pathology considered. More data are needed to consider jitter as a predictor of BoNT-A clinical efficacy.
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Affiliation(s)
- Hélène Moron
- Department of Functional Exploration of the Nervous System and Acupuncture, CHU Nîmes, Univ Montpellier, 30029 Nîmes, France;
- EuroMov DHM, IMT Ales, Univ Montpellier, 34090 Montpellier, France;
- CAMIN, INRIA, Univ Montpellier, 34090 Montpellier, France;
- Correspondence:
| | - Corine Gagnard-Landra
- Department of Functional Exploration of the Nervous System and Acupuncture, CHU Nîmes, Univ Montpellier, 30029 Nîmes, France;
| | - David Guiraud
- CAMIN, INRIA, Univ Montpellier, 34090 Montpellier, France;
| | - Arnaud Dupeyron
- EuroMov DHM, IMT Ales, Univ Montpellier, 34090 Montpellier, France;
- Department of Physical and Rehabilitation Medicine, CHU Nîmes, Univ Montpellier, 30029 Nîmes, France
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Near-fiber electromyography. Clin Neurophysiol 2021; 132:1089-1104. [PMID: 33774377 DOI: 10.1016/j.clinph.2021.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 01/28/2021] [Accepted: 02/05/2021] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Describe and evaluate the concepts of near fiber electromyography (NFEMG), the features used, including near fiber motor unit potential (NFMUP) duration and dispersion, which relate to motor unit distal axonal branch and muscle fiber conduction time dispersion, and NFMUP segment jitter, a new measure of the temporal variability of neuromuscular junction transmission (NMJ), and axonal branch and muscle fibre conduction for the near fibres (i.e. NF jitter), and the methods for obtaining their values. METHODS Trains of high-pass filtered motor unit potentials (MUPs) (i.e. NFMUP trains) were extracted from needle-detected EMG signals to assess changes in motor unit (MU) morphology and electrophysiology caused by neuromuscular disorders or ageing. Evaluations using simulated needle-detected EMG data were completed and example human data are presented. RESULTS NFEMG feature values can be used to detect axonal sprouting, conduction slowing and NMJ transmission delay as well as changes in MU fiber diameter variability, and NF jitter. These changes can be detected prior to alterations of MU size or numbers. CONCLUSIONS The evaluations clearly demonstrate and the example data support that NFMUP duration and dispersion reflect MU distal axonal branching, conduction slowing and NMJ transmission delay and/or MU fiber diameter variability and that NFMUP jiggle and segment jitter reflect NF jitter. SIGNIFICANCE NFEMG can detect early changes in MU morphology and/or electrophysiology and has the potential to augment clinical diagnosis and tracking of neuromuscular disorders.
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Deymeer F. Myasthenia gravis: MuSK MG, late-onset MG and ocular MG. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2021; 39:345-352. [PMID: 33458590 PMCID: PMC7783433 DOI: 10.36185/2532-1900-038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 11/03/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction which affects all striated muscles, resulting in fluctuating weakness. Approaching MG as a disease with subgroups having different clinical, serological and genetic features is crucial in predicting the progression and planning treatment. Three relatively less frequently seen subtypes of MG are the subject of this review: MG with anti-MuSK antibodies (MuSK MG), non-thymomatous late-onset MG (LOMG), and ocular MG (OMG). In addition to reviewing the literature, mainly from a clinical point of view, our experience in each of the subgroups, based on close to 600 patients seen over a 10 year period, is related. MuSK MG is a severe disease with predominant bulbar involvement. It is more common in women and in early-onset patients. With the use of high dose corticosteroids, azathioprine and more recently rituximab, outcome is favorable, though the patients usually require higher maintenance doses of immunosuppressives. LOMG with onset ≥ 50 years of age is more common in men and ocular onset is common. Frequency of anti-AChR and anti-titin antibodies are high. Although it can be severe in some patients, response to treatment is usually very good. OMG is reported to be more frequent in men in whom the disease has a later onset. Anti-AChR antibodies are present in about half of the patients. Generalization is less likely when symptoms remain confined to ocular muscles for 2 years. Low dose corticosteroids are usually sufficient. Thyroid disease is the most common autoimmune disease accompanying all three subgroups.
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Affiliation(s)
- Feza Deymeer
- Department of Neurology, Istanbul Medical Faculty, Istanbul University, Istanbul, Turkey
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Zambelis T, Anagnostou E. Reference values for voluntary SFEMG jitter in orbicularis oculi, frontalis, extensor digitorum communis and tibialis anterior using a concentric needle electrode. Neurophysiol Clin 2021; 51:387-389. [PMID: 33478863 DOI: 10.1016/j.neucli.2021.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 12/01/2022] Open
Affiliation(s)
- Thomas Zambelis
- National and Kapodistrian University of Athens, 1stDepartment of Neurology, Aeghinition Hospital, 74, Vass. Sofias Ave. 115-28, Athens, Greece.
| | - Evangelos Anagnostou
- National and Kapodistrian University of Athens, 1stDepartment of Neurology, Aeghinition Hospital, 74, Vass. Sofias Ave. 115-28, Athens, Greece
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Kouyoumdjian JA, Paiva GP, Stålberg E. Concentric Needle Jitter in 97 Myasthenia Gravis Patients. Front Neurol 2020; 11:600680. [PMID: 33281737 PMCID: PMC7691317 DOI: 10.3389/fneur.2020.600680] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 10/13/2020] [Indexed: 11/24/2022] Open
Abstract
Objectives: To estimate the jitter parameters (single-fiber electromyography) in myasthenia gravis patients mostly by electrical activation in Frontalis, Orbicularis Oculi, and Extensor Digitorum muscles using a concentric needle electrode. Methods: Between 2009 and 2019, a total of 97 myasthenia gravis patients, 52 male, and mean age 54 years were included. Results: Any abnormal jitter parameter in individual muscles was 90.5% (Frontalis), 88.5% (Orbicularis Oculi), and 86.6% (Extensor Digitorum). Any jitter parameter combining Orbicularis Oculi and Frontalis muscle was abnormal in 100% for the ocular, and in 92.9% for the generalized myasthenia gravis. The most abnormal muscle was Orbicularis Oculi for the generalized, and Frontalis for the ocular myasthenia gravis. The decrement was abnormal in 78.4%, 85.9% for the generalized, and 25% for the ocular myasthenia gravis. The mean jitter ranged from 14.2 to 86 μs (mean 33.3 μs) for the ocular myasthenia gravis and from 14.4 to 220.4 μs (mean 66.3 μs) for the generalized myasthenia gravis. The antibody titers tested positive in 86.6%, 91.8% for the generalized, and 50% for the ocular myasthenia gravis. Thymectomy was done in 48.5%, thymoma was found in 19.6%, and myasthenic crisis occurred by 21.6%. Conclusion: The jitter parameters achieved a 100% abnormality in ocular myasthenia gravis if both the Orbicularis Oculi and Frontalis muscles were tested. There was a high jitter abnormality in generalized myasthenia gravis cases with one muscle tested, with about a 2% increase in sensitivity when a second is added. Concentric needle electrode jitter had high sensitivity similar to the single fiber electrode (93.8%), followed by antibody titers (86.6%), and abnormal decrement (78.4%).
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Affiliation(s)
- João Aris Kouyoumdjian
- Laboratório Investigação Neuromuscular, Faculdade Estadual Medicina São José do Rio Preto, São Paulo, Brazil
| | - Gabriel Pina Paiva
- Laboratório Investigação Neuromuscular, Faculdade Estadual Medicina São José do Rio Preto, São Paulo, Brazil
| | - Erik Stålberg
- Department of Clinical Neurophysiology, Institute of Neurosciences, Uppsala University, Uppsala, Sweden
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Nguyen T, Phan CL, Supsupin E, Sheikh K. Therapeutic and Diagnostic Challenges in Myasthenia Gravis. Neurol Clin 2020; 38:577-590. [PMID: 32703470 DOI: 10.1016/j.ncl.2020.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
"Myasthenia gravis (MG) is the most common autoimmune neuromuscular disorder. This article highlights several cases that the practicing neurologist may encounter in the treatment of MG. Diagnostic uncertainty continues to be an issue in patients who are seronegative to the 2 most common antibodies, acetylcholine receptor and muscle-specific tyrosine kinase (MuSK). Specific populations of patients with MG including MuSK MG, thymomatous MG, refractory MG, and pregnant women also require special consideration. This article reviews specific cases and an update on current management."
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Affiliation(s)
- Thy Nguyen
- Department of Neurology, McGovern Medical School, University of Texas Houston Health Science Center, 6431 Fannin Street, MSE R 462, Houston, TX 77030, USA.
| | - Cecile L Phan
- 7-125 Clinical Sciences Building, 2J2.00 WC Mackenzie Health Sciences Centre, 8440 112 St. NW, Edmonton, Alberta, T6G 2R7 Canada
| | - Emilio Supsupin
- Department of Diagnostic and Interventional Imaging, 6431 Fannin St. 2.103 MSMB, Houston, Texas 77030, USA
| | - Kazim Sheikh
- Department of Neurology, McGovern Medical School, University of Texas Houston Health Science Center, 6431 Fannin street, MSE R454 Houston, TX 77030, USA
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18
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Complex Repetitive Discharges: A Sign of Motor Axonal Reinnervation? Brain Sci 2020; 10:brainsci10060349. [PMID: 32517058 PMCID: PMC7348810 DOI: 10.3390/brainsci10060349] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/22/2020] [Accepted: 06/01/2020] [Indexed: 11/26/2022] Open
Abstract
Complex repetitive discharges (CRDs) are poorly understood phenomena in needle electromyography (EMG) recordings. The data presented here suggest that CRDs may mainly be a sign of motor unit reinnervation. EMG “video” data of 108 CRDs from neurogenic (ND, n = 39) and myogenic (MD, n = 14) disorders were retrospectively analyzed for cycle duration, potential-free time intervals, spike components (SC), maximum amplitudes, blockade, and increased jitter. CRD-SC in ND disorders (9.3 ± 7.8) outnumbered those in MD disorders (6.3 ± 6.2). The CRD cycle duration was correlated with SC and silent periods (p each < 0.000001). Blockade was observed in 36% and increased jitter in 27% of the CRDs. A higher number of CRD-SC in ND vs. MD fits the known differences in motor unit dimensions. Blockade and increased jitter are known features of diseased neuromuscular junctions, such as during reinnervation. The SC patterns of single CRD cycles resemble reinnervation potentials. Thus, CRDs may result from myo-axonal re-excitation in sprouting motor units. The purpose of this investigation was to better understand the circumstances under which CRDs may occur and eventually to contribute to the understanding of their pathogenesis.
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19
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Musa AMM, Ahmed AEM. Reference Jitter Values for Concentric Needle Electrode of Orbicularis Oculi and Frontalis Muscles Using Voluntary Activation Method in Sudanese Population. Sci Rep 2020; 10:1031. [PMID: 31974444 PMCID: PMC6978519 DOI: 10.1038/s41598-020-58037-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 01/09/2020] [Indexed: 11/18/2022] Open
Abstract
Single fibre electromyography is the most sensitive neurophysiological test for the diagnosis of neuromuscular junction disorders, particularly myasthenia gravis. The study aimed at establishing concentric needle (CN) normal jitter values for voluntarily activated orbicularis-oculi (V-OOc) & Frontalis (V-FRO) muscles in Sudanese population. 57 healthy volunteers (20 males & 37 females) were included in the study (mean Age 43.6 ± 14.2 years, range 18–70 years). V-OOc and V-FRO were tested in the same individual using CN. Jitter values were expressed as the mean consecutive difference (MCD) of 30 potential pairs in microseconds. The mean jitter, mean individual fibre pairs jitter & mean outliers jitter values with (upper 95% Confidence Limit-CL) for [OOc] were [26.9 ± 3.3 (31.97), 26.1 ± 8.9 (41.8) & 38.5 ± 5.7 (49.0) µs] & for [FRO] were [27.1 ± 3.0 (31.32), 26.4 ± 9.4 (42.9) & 39.9 ± 5 (49.2) µs] respectively. The suggested practical upper limits for mean jitter & for outliers were (32, 49 µs) for OOc & (31, 49 µs) for FRO. Our CN-jitter values were within the range of the few published studies. The study was unique in that it established and compared between CN reference jitter values of two voluntarily activated facial muscles (V-OOc & V-FRO) in the same individual in large number of healthy subjects.
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Affiliation(s)
- Afraa M M Musa
- Department of Physiology, Faculty of Medicine, University of Khartoum, El Qasr Street, Khartoum, P.O. BOX 102, Sudan.
| | - Ammar E M Ahmed
- Department of Physiology, Faculty of Medicine, University of Khartoum, El Qasr Street, Khartoum, P.O. BOX 102, Sudan
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20
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Jamora RDG, Espiritu AI, Santiago JJ, Wohldorf JJ, Cuanang JR. Blepharospasm as the presenting feature of papillary thyroid cancer and parathyroid adenoma. J Clin Neurosci 2019; 72:460-463. [PMID: 31889644 DOI: 10.1016/j.jocn.2019.12.025] [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] [Received: 09/09/2019] [Accepted: 12/16/2019] [Indexed: 11/17/2022]
Abstract
Blepharospasm is a type of focal dystonia depicted by periodic and spontaneous closure of the orbicularis oculi and surrounding muscles. Typical secondary etiologies of blepharospasm may include ophthalmologic and structural brain lesions. In this article, we report a novel case of a patient with a biopsy-proven concurrent papillary carcinoma of the thyroid gland and adenoma of the parathyroid gland with blepharospasm as an exceptionally unique initial manifestation. This report showed that a diagnostic work-up for causes of blepharospasm may include a search for these neoplasm and surgical removal of these masses may offer significant symptomatic control of the focal dystonia.
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Affiliation(s)
- Roland Dominic G Jamora
- Movement Disorders Service and Section of Neurology, Institute for Neurosciences, St. Luke's Medical Center, Quezon City, Philippines; Department of Neurosciences, College of Medicine, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines.
| | - Adrian I Espiritu
- Department of Neurosciences, College of Medicine, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines; Department of Clinical Epidemiology, College of Medicine, University of the Philippines Manila, Philippines
| | - Janet J Santiago
- Section of Neurology, Institute for Neurosciences, St. Luke's Medical Center, Quezon City, Philippines
| | - Jocelyn J Wohldorf
- Section of Endocrinology, Department of Medicine, St. Luke's Medical Center, Quezon City, Philippines
| | - Joven R Cuanang
- Section of Neurology, Institute for Neurosciences, St. Luke's Medical Center, Quezon City, Philippines
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21
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Mohamed Daud A, Mat Baki M, Azman M, Kamaruzaman E, Mohamed AS. Unusual Presentation of Myasthenia Crisis Following Thymectomy and Thyroidectomy. Indian J Otolaryngol Head Neck Surg 2019; 71:118-120. [PMID: 31741945 DOI: 10.1007/s12070-017-1146-x] [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: 02/24/2016] [Accepted: 05/24/2017] [Indexed: 11/28/2022] Open
Abstract
Respiratory distress after thyroidectomy and thymectomy can be challenging. We encountered a 70-year-old lady with a long-standing goiter with concomitant thymoma. She underwent the surgery and developed respiratory distress upon extubation with loss of laryngeal sensation causing severe aspiration. She was diagnosed myasthenia gravis and symptoms resolved with MG treatments.
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Affiliation(s)
- Aidayanti Mohamed Daud
- 1Otorhinolaryngology-Head and Neck Department, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Wilayah Persekutuan Kuala Lumpur Malaysia
| | - Marina Mat Baki
- 1Otorhinolaryngology-Head and Neck Department, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Wilayah Persekutuan Kuala Lumpur Malaysia
| | - Mawaddah Azman
- 1Otorhinolaryngology-Head and Neck Department, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Wilayah Persekutuan Kuala Lumpur Malaysia
| | - Esa Kamaruzaman
- 2Anaesthesiology and Intensive Care Department, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Abdullah Sani Mohamed
- 1Otorhinolaryngology-Head and Neck Department, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Wilayah Persekutuan Kuala Lumpur Malaysia
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22
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Bromberg MB. The motor unit and quantitative electromyography. Muscle Nerve 2019; 61:131-142. [PMID: 31579956 DOI: 10.1002/mus.26718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 12/13/2022]
Abstract
Electromyography (EMG) assesses the anatomic motor unit (A-MU), but knowledge of its anatomy, physiology, and changes with pathology is limited. The electrophysiological motor unit (E-MU) and its motor unit potential (E-MUP) represents a fraction of the A-MU. Routine EMG assesses a limited number of E-MUP waveform characteristics (metrics) and their magnitudes qualitatively scaled in a nonlinear manner. Another approach is quantitative EMG (QEMG), whereby 20+ E-MUPs are extracted and both basic and derived metrics obtained and values expressed quantitatively. In diseased muscle, many E-MUP metrics may be normal, which complicates diagnostic interpretation. In QEMG, E-MUP metrics can be clustered and statistical analyses performed to assign probabilities that E-MUPs (and the muscle) are normal, neuropathic, or myopathic. In this article we review what is known about the A-MU, the restricted E-MU, E-MUP metrics, and what QEMG offers currently and in the future.
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Affiliation(s)
- Mark B Bromberg
- Department of Neurology, University of Utah, Salt Lake City, Utah
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23
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Nicolau S, Kao JC, Liewluck T. Trouble at the junction: When myopathy and myasthenia overlap. Muscle Nerve 2019; 60:648-657. [PMID: 31449669 DOI: 10.1002/mus.26676] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
Abstract
Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota
| | - Justin C Kao
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
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24
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Abstract
Lambert-Eaton myasthenic syndrome is a paraneoplastic or primary autoimmune neuromuscular junction disorder characterized by proximal weakness, autonomic dysfunction and ariflexia. The characteristic symptoms are thought to be caused by antibodies generated against the P/Q-type voltage-gated calcium channels present on presynaptic nerve terminals and by diminished release of acetylcholine. More than half of Lambert-Eaton myasthenic syndrome cases are associated with small cell lung carcinoma. Diagnosis is confirmed by serologic testing and electrophysiologic studies. 3,4-diaminopyridine is effective symptomatic treatment of LEMS.
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Affiliation(s)
- Vita G Kesner
- Neurology Department, 12 Executive Park Drive NE, Atlanta, GA 30329, USA.
| | - Shin J Oh
- University of Alabama at Birmingham, Department of Neurology, SC 350, 1720 2nd Ave South, Birmingham, AL 35294, USA
| | - Mazen M Dimachkie
- 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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25
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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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Dede HÖ, Şırın NG, Kocasoy-Orhan E, Idrısoğlu HA, Baslo MB. Electrophysiological Findings of Subclinical Lower Motor Neuron Involvement in Degenerative Upper Motor Neuron Diseases. ACTA ACUST UNITED AC 2019; 57:228-233. [PMID: 32952426 DOI: 10.29399/npa.23387] [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] [Received: 09/20/2018] [Accepted: 03/26/2019] [Indexed: 12/11/2022]
Abstract
Introduction The present study is an examination of possible subclinical involvement of lower motor neuron (LMN) in patients with primary lateral sclerosis (PLS) and hereditary spastic paraparesis (HSP) electrophysiologically. Methods Nine PLS patients and 5 HSP patients were prospectively analyzed. Jitter measurement with concentric needle electrode (25 mm, 30 G) (CN-jitter) recorded from right extensor digitorum muscle during voluntary contraction with 1 kHz high-pass frequency filter set. European Myelopathy Score (EMS) was used to evaluate disability. The relationship between disability score and jitter values was investigated. Results HSP patients had suffered from the disease for longer period of time (p<0.001). Mean jitter values of patients with PLS and HSP were 26.5±12.1 µs and 30.8±34.8 µs, and the number of individual high jitters (>43 microseconds) observed in the PLS and HSP groups was 16/180 and 9/100, respectively without a significant intergroup difference. The ratio of patients with an abnormal jitter study were higher in HSP group (60%) compared to PLS (22%) (p<0.05). Potential pairs with blocking were present in HSP group (7 of 100 potential pairs) but not seen in PLS patients. EMS values were significantly lower in patients having potential pairs with high jitter and blocking compared to those without high jitter and blocking. Conclusion The present study has demonstrated that early signs of LMN dysfunction can be detected electrophysiologically by CN-jitter in patients with UMN involvement. These electrophysiological findings in these patients with longer disease duration and lower clinical scores may be explained by spreading of the disease to LMNs or transsynaptic degeneration and its contribution in disease progression.
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Affiliation(s)
- Hava Özlem Dede
- Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey
| | - Nermin Görkem Şırın
- Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey
| | - Elif Kocasoy-Orhan
- Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey
| | - Halil Atilla Idrısoğlu
- Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey
| | - Mehmet Barış Baslo
- Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey
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Increased Single-Fiber Jitter Level Is Associated With Reduction in Motor Function With Aging. Am J Phys Med Rehabil 2019; 97:551-556. [PMID: 29498943 DOI: 10.1097/phm.0000000000000915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Age-associated skeletal muscle weakness is a major contributing factor to an increased late life mortality and morbidity, but its neurobiology is poorly understood. Previously, we provided histological evidence of dying-back axonal degeneration of motor neurons and denervation of neuromuscular junctions in age-associated muscle weakness. Given this, we aimed to evaluate the relation between impaired neuromuscular transmission and various aspects of age-associated muscle weakness. DESIGN We compared two electrophysiological measures, single-fiber jitter and compound motor action potential in mice of different age groups, and correlated them with various physical performance measures, such as grip strength, standing and walking time, and treadmill performance. RESULTS Consistent with our previous histological data, single-fiber jitter, a measure of neuromuscular junction transmission, was significantly increased in older animals, whereas compound motor action potential shows no difference between young and old age groups. Neither jitter nor compound motor action potential correlated with any of physical performance measures, except for jitter and standing activity. CONCLUSIONS Impaired neuromuscular transmission-represented as increase in single-fiber electromyography jitter level-reflects decline in motor function with aging.
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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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29
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Italian recommendations for the diagnosis and treatment of myasthenia gravis. Neurol Sci 2019; 40:1111-1124. [PMID: 30778878 DOI: 10.1007/s10072-019-03746-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/31/2019] [Indexed: 12/30/2022]
Abstract
Myasthenia gravis is a well-treatable disease, in which a prompt diagnosis and an adequate management can achieve satisfactory control of symptoms in the great majority of patients. Improved knowledge of the disease pathogenesis has led to recognition of patient subgroups, according to associated antibodies, age at onset and thymus pathology, and to a more personalized treatment. When myasthenia gravis is suspected on clinical grounds, diagnostic confirmation relies mainly on the detection of specific antibodies. Neurophysiological studies and, to a lesser extent, clinical response to cholinesterase inhibitors support the diagnosis in seronegative patients. In these cases, the differentiation from congenital myasthenia can be challenging. Treatment planning must consider weakness extension and severity, disease subtype, thymus pathology, together with patient characteristics and comorbidities. Since most subjects with myasthenia gravis require long-term immunosuppressive therapy, surveillance of expected and potential adverse events is critical. For patients refractory to conventional immunosuppression, the use of biologic agents is highly promising. These recommendations are addressed to non-experts on neuromuscular transmission disorders. The diagnostic procedures and therapeutic approaches hereafter described are largely accessible in Italy.
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Zalewska E, Gawel M. Identification of components from distant fibers in a recorded single muscle fiber potential (SFP) – a new approach to the SFP criteria. Neurophysiol Clin 2019; 49:69-80. [DOI: 10.1016/j.neucli.2018.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 09/24/2018] [Accepted: 09/27/2018] [Indexed: 10/28/2022] Open
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31
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Abstract
Single fiber electromyography (SFEMG) is a highly selective technique that permits assessment of individual muscle fiber action potentials (MFAPs). This selectivity is achieved with a specialized concentric needle electrode with a 25-μm diameter recording surface located in a side port 3mm from the needle tip. Additional selectivity is achieved with 500-Hz low-frequency filtering. An oscilloscope with a trigger and delay line enables identification of time-locked MFAPs within the same motor unit. SFEMG techniques allow assessment of two important features of the motor unit: jitter and fiber density (FD). Neuromuscular jitter is a direct measure of neuromuscular transmission and reflects the temporal variation in end-plate potentials reaching threshold to elicit a MFAP. SFEMG may be used to assess paired jitter with voluntary activation or by axonal stimulation of motor nerve branches to individual end plates. SFEMG is the most sensitive clinical test for neuromuscular junction disease and is often abnormal in clinically unaffected muscles in patients with myasthenia gravis (MG) and Lambert-Eaton myasthenia (LEM). Normal jitter findings in a clinically weak muscle exclude neuromuscular junction disease as a cause for weakness in that muscle. FD measurements assess the local concentration of muscle fibers within a motor unit and provide a sensitive in vivo assessment of reinnervation.
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Affiliation(s)
- Vern C Juel
- Department of Neurology, Duke University School of Medicine, Durham, NC, United States.
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32
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Yao B, Klein CS, Hu H, Li S, Zhou P. Motor Unit Properties of the First Dorsal Interosseous in Chronic Stroke Subjects: Concentric Needle and Single Fiber EMG Analysis. Front Physiol 2018; 9:1587. [PMID: 30559674 PMCID: PMC6287192 DOI: 10.3389/fphys.2018.01587] [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: 05/04/2018] [Accepted: 10/23/2018] [Indexed: 02/04/2023] Open
Abstract
The purpose of this study was to better understand changes in motor unit electrophysiological properties in people with chronic stroke based on concentric needle electromyography (EMG) and single fiber EMG recordings. The first dorsal interosseous (FDI) muscle was studied bilaterally in eleven hemiparetic stroke subjects. A significant increase in mean fiber density (FD) was found in the paretic muscle compared with the contralateral side based on single fiber EMG (1.6 ± 0.2 vs. 1.3 ± 0.1, respectively, P = 0.003). There was no statistically significant difference between the paretic and contralateral sides in most concentric needle motor unit action potential (MUAP) parameters, such as amplitude (768.7 ± 441.7 vs. 855.0 ± 289.9 μV), duration (8.9 ± 1.8 vs. 8.68 ± 0.9 ms) and size index (1.2 ± 0.5 vs. 1.1 ± 0.3) (P > 0.18), nor was there a significant difference in single fiber EMG recorded jitter (37.0 ± 9.6 vs. 39.9 ± 10.6 μs, P = 0.45). The increase in FD suggests motor units of the paretic FDI have enlarged due to collateral reinnervation. However, sprouting might be insufficient to result in a statistically significant change in the concentric needle MUAP parameters. Single fiber EMG appears more sensitive than concentric needle EMG to reflect electrophysiological changes in motor units after stroke. Both single fiber and concentric needle EMG recordings may be necessary to better understand muscle changes after stroke, which is important for development of appropriate rehabilitation strategies. The results provide further evidence that motor units are remodeled after stroke, possibly in response to a loss of motoneurons.
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Affiliation(s)
- Bo Yao
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China.,Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Cliff S Klein
- Guangdong Work Injury Rehabilitation Center, Guangzhou, China
| | - Huijing Hu
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States.,Guangdong Work Injury Rehabilitation Center, Guangzhou, China
| | - Sheng Li
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Ping Zhou
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
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Concentric or monopolar electrode for jitter determination in orbicularis oculi. Clin Neurophysiol 2018; 129:2552-2556. [DOI: 10.1016/j.clinph.2018.09.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 08/29/2018] [Accepted: 09/23/2018] [Indexed: 11/20/2022]
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Haddix SG, Lee YI, Kornegay JN, Thompson WJ. Cycles of myofiber degeneration and regeneration lead to remodeling of the neuromuscular junction in two mammalian models of Duchenne muscular dystrophy. PLoS One 2018; 13:e0205926. [PMID: 30379896 PMCID: PMC6209224 DOI: 10.1371/journal.pone.0205926] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/03/2018] [Indexed: 12/02/2022] Open
Abstract
Mice lacking the sarcolemmal protein dystrophin, designated mdx, have been widely used as a model of Duchenne muscular dystrophy. Dystrophic mdx mice as they mature develop notable morphological abnormalities to their neuromuscular junctions, the peripheral cholinergic synapses responsible for activating muscle fibers. Most obviously the acetylcholine receptor aggregates are fragmented into small non-continuous, islands. This contrasts with wild type mice whose acetylcholine receptor aggregates are continuous and pretzel-shaped in appearance. We show here that these abnormalities in mdx mice are also present in a canine model of Duchenne muscular dystrophy and provide additional evidence to support the hypothesis that NMJ remodeling occurs due to myofiber degeneration and regeneration. Using a method to investigate synaptic AChR replacement, we show that neuromuscular junction remodeling in mdx animals is caused by muscle fiber degeneration and regeneration at the synaptic site and is mimicked by deliberate myofiber injury in wild type mice. Importantly, the innervating motor axon plays a crucial role in directing the remodeling of the neuromuscular junction in dystrophy, as has been recorded in aging and deliberate muscle fiber injury in wild type mice. The remodeling occurs repetitively through the life of the animal and the changes in junctions become greater with age.
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Affiliation(s)
- Seth G. Haddix
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| | - Young il Lee
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, United States of America
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Joe N. Kornegay
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, United States of America
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, United States of America
| | - Wesley J. Thompson
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas, United States of America
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
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Sirin NG, Kocasoy Orhan E, Durmus H, Deymeer F, Baslo MB. Repetitive nerve stimulation and jitter measurement with disposable concentric needle electrode in newly diagnosed myasthenia gravis patients. Neurophysiol Clin 2018; 48:261-267. [DOI: 10.1016/j.neucli.2018.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/13/2018] [Accepted: 01/19/2018] [Indexed: 10/17/2022] Open
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Hamel J, Logigian EL. The prognosis of electrodiagnosis. Muscle Nerve 2018; 58:178-181. [DOI: 10.1002/mus.26162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Johanna Hamel
- Department of Neurology, University of Rochester Medical Center601 Elmwood Avenue Rochester New York14642 USA
| | - Eric L. Logigian
- Department of Neurology, University of Rochester Medical Center601 Elmwood Avenue Rochester New York14642 USA
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Tawfeek AA, Nawito AM, Azmy RM, Hassan A, Afifi LM, Elkholy SH. Role of concentric needle Single Fiber Electromyography in detection of subclinical motor involvement in carpal tunnel syndrome. THE EGYPTIAN JOURNAL OF NEUROLOGY, PSYCHIATRY AND NEUROSURGERY 2018; 54:2. [PMID: 29780222 PMCID: PMC5954771 DOI: 10.1186/s41983-018-0004-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 03/23/2018] [Indexed: 11/12/2022] Open
Abstract
Background Conventional motor nerve conduction studies are usually normal in early and mild carpal tunnel syndrome (CTS). Single-fiber electromyography (SFEMG) measures the mean consecutive difference (MCD) as an expression of the variability in impulse transmission over the motor endplates and along the nerve fibers distally to the last branching point and along the muscle fibers. Application of concentric needle SFEMG in a group of CTS patients who showed pure sensory abnormalities in nerve conduction studies to examine for subclinical motor involvement. Methods Thirty CTS patients having only sensory involvement proved clinically and by conventional electrophysiological studies were included in addition to 30 control subjects. Concentric needle SFEMG was performed to the abductor pollicis brevis (APB), abductor digiti minimi (ADM), and extensor digitorum communis (EDC) muscles. Results There was a statistically significant difference in the MCD between the patient and control groups in the APB only (p = 0.038). Conclusions The results suggest the presence of a subclinical motor median neuropathy at the wrist in patients with early and mild carpal tunnel syndrome and highlight the validity of the concentric needle SFEMG in early neuropathies. Trial registration PACTR201802002971380 registered 12 February 2018, retrospectively registered.
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Affiliation(s)
- Aliaa A Tawfeek
- 1Clinical Neurophysiology Unit, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Amani M Nawito
- 1Clinical Neurophysiology Unit, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Radwa M Azmy
- 1Clinical Neurophysiology Unit, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Amr Hassan
- 2Neurology department, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Lamia M Afifi
- 1Clinical Neurophysiology Unit, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Saly H Elkholy
- 1Clinical Neurophysiology Unit, Kasr Alainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt
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Artuğ NT, Goker I, Bolat B, Osman O, Orhan EK, Baslo MB. New features for scanned bioelectrical activity of motor unit in health and disease. Biomed Signal Process Control 2018. [DOI: 10.1016/j.bspc.2017.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
PURPOSE OF REVIEW This article discusses the pathogenesis, diagnosis, and management of autoimmune myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS). RECENT FINDINGS Recognition of new antigenic targets and improved diagnostic methods promise to improve the diagnosis of MG, although the clinical phenotypes associated with newer antibodies have not yet been defined. Future therapies might specifically target the aberrant immune response. The apparent increase in the prevalence of MG is not fully explained. Results of a long-awaited trial of thymectomy support the practice of performing a thymectomy under specific conditions. SUMMARY The current treatment options are so effective in most patients with MG or LEMS that in patients with refractory disease the diagnosis should be reconsidered. The management of MG is individualized, and familiarity with mechanisms, adverse effects, and strategies to manage these commonly used treatments improves outcome. Patient education is important. LEMS, frequently associated with an underlying small cell lung cancer, is uncommon, and the mainstay of treatment is symptomatic in most patients.
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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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Kazamel M, Warren PP. History of electromyography and nerve conduction studies: A tribute to the founding fathers. J Clin Neurosci 2017. [PMID: 28629678 DOI: 10.1016/j.jocn.2017.05.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The early development of nerve conduction studies (NCS) and electromyography (EMG) was linked to the discovery of electricity. This relationship had been concluded by observing the effect of applying electricity to the body of an animal and discovering that nerves and muscles themselves could produce electricity. We attempt to review the historical evolution of NCS and EMG over the last three centuries by reviewing the landmark publications of Galvani, Adrian, Denny-Brown, Larrabee, and Lambert. In 1771, Galvani showed that electrical stimulation of animal muscle tissue produced contraction and, thereby, the concept of animal electricity was born. In 1929, Adrian devised a method to record a single motor unit potential by connecting concentric needle electrodes to an amplifier and a loud speaker. In 1938, Denny-Brown described the fasciculation potentials and separated them from fibrillations. Toward the end of World War II, Larrabee began measuring the compound muscle action potential in healthy and injured nerves of war victims. In 1957, Lambert and Eaton described the electrophysiologic features of a new myasthenic syndrome associated with lung carcinoma. Overall, research on this topic was previously undertaken by neurophysiologists and then later by neurologists, with Adrian most likely being the first neurologist to be involved. The field greatly benefited from the invention of equipment that was capable of amplifying small bioelectrical currents by the beginning of the 20th century. Significant scientific and technical advances were later made during and after World War II which provided a large patient population with nerve injuries to study.
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Affiliation(s)
- Mohamed Kazamel
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Paula Province Warren
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Chung T, Park JS, Kim S, Montes N, Walston J, Höke A. Evidence for dying-back axonal degeneration in age-associated skeletal muscle decline. Muscle Nerve 2017; 55:894-901. [PMID: 27464347 DOI: 10.1002/mus.25267] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 07/21/2016] [Accepted: 07/26/2016] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Age-associated muscle strength decline is a major contributing factor to increased late-life functional decline and comorbidity, and is strongly associated with early mortality. Although all parts of the neuromuscular system seem to be affected by aging, dying-back of motor axons likely plays a major role. METHODS We compared the degeneration in ventral roots and neuromuscular junction denervation in young and aged mice and correlated the findings with strength and electrophysiological measures. RESULTS With normal aging, there is little decline in motor axon numbers in the ventral roots, but the neuromuscular junctions show marked partial denervation that is associated with increased jitter on stimulated single fiber electromyography and a decrease in muscle strength. CONCLUSIONS These findings suggest that dying-back axonal degeneration may be partially responsible for the electrophysiological and strength changes observed with aging. Muscle Nerve 55: 894-901, 2017.
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Affiliation(s)
- Tae Chung
- Department of Physical Medicine and Rehabilitation, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Jae Sung Park
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA.,Department of Physical Education, Kongju National University, Gongju, Republic of Korea
| | - Sangri Kim
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA
| | - Nataly Montes
- Department of Physical Medicine and Rehabilitation, VA Caribbean Healthcare System, San Juan, Puerto Rico
| | - Jeremy Walston
- Department of Medicine, Johns Hopkins, Baltimore, Maryland, USA
| | - Ahmet Höke
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, 21205, USA
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Morren JA, Levin KH, Shields RW. Diagnostic Accuracy of Single Fiber Electromyography for Myasthenia Gravis in Patients Followed Longitudinally. J Clin Neurophysiol 2017; 33:469-474. [PMID: 27749461 DOI: 10.1097/wnp.0000000000000285] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION The literature lacks data on accuracy of single fiber electromyography (SFEMG) for myasthenia gravis (MG) patients followed longitudinally. METHODS We included patients with a clinical suspicion of MG who received SFEMG and follow-up at our institution between 2003 and 2013. Data collected included demographics, symptom details, clinical deficits, other diagnostic testing results, MG medication regimen, duration on treatment, response to therapy, and ultimate diagnosis after follow-up. When available, information was also extracted from the MG-specific Activities of Daily Living, MG Quality of Life, and European Quality of Life assessments before and after SFEMG. RESULTS Three hundred forty eight SFEMG patients met inclusion criteria. Myasthenia gravis was ultimately diagnosed in 31% (19% ocular, 12% generalized). A sensitivity of 78% was seen for MG regardless of subtype, 73% for ocular MG, and 85% for generalized MG. A specificity of 91% was obtained for MG of either ocular or generalized subtype. CONCLUSIONS The diagnostic accuracy of SFEMG using this methodology minimizing incorporation bias is more reliable than that usually described in previous studies. There is utility in increasing diagnostic yield when SFEMG results are combined with clinical data and those from other diagnostic tests, particularly serology.
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Affiliation(s)
- John A Morren
- *Neuromuscular Center, Neurological Institute, Cleveland Clinic, Cleveland, Ohio, U.S.A.; and †Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH
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Liu MS, Niu JW, Li Y, Guan YZ, Cui LY. Quantitating Changes in Jitter and Spike Number Using Concentric Needle Electrodes in Amyotrophic Lateral Sclerosis Patients. Chin Med J (Engl) 2017; 129:1036-40. [PMID: 27098787 PMCID: PMC4852669 DOI: 10.4103/0366-6999.180533] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Background: Single-fiber electromyography (SFEMG) has been suggested as a quantitative method for supporting chronic partial denervation in amyotrophic lateral sclerosis (ALS) by the revised EI Escorial criteria. Although concentric needle (CN) electrodes have been used to assess jitter in myasthenia gravis patients and healthy controls, there are few reports using CN electrodes to assess motor unit instability and denervation in neurogenic diseases. The aim of this study was to determine whether quantitative changes in jitter and spike number using CN electrodes could be used for ALS studies. Methods: Twenty-seven healthy controls and 23 ALS patients were studied using both CN and single-fiber needle (SFN) electrodes on the extensor digitorum communis muscle with an SFEMG program. The SFN-jitter and SFN-fiber density data were measured using SFN electrodes. The CN-jitter and spike number were measured using CN electrodes. Results: The mean CN-jitter was significantly increased in ALS patients (47.3 ± 17.0 μs) than in healthy controls (27.4 ± 3.3 μs) (P < 0.001). Besides, the mean spike number was significantly increased in ALS patients (2.5 ± 0.5) than in healthy controls (1.7 ± 0.3) (P < 0.001). The sensitivity and specificity in the diagnosis of ALS were 82.6% and 92.6% for CN-jitter (cut-off value: 32 μs), and 91.3% and 96.3% for the spike number (cut-off value: 2.0), respectively. There was no significant difference between the SFN-jitter and CN-jitter in ALS patients; meanwhile, there was no significant difference between the SFN-jitter and CN-jitter in healthy controls. Conclusion: CN-jitter and spike number could be used to quantitatively evaluate changes due to denervation-reinnervation in ALS.
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Affiliation(s)
| | | | | | | | - Li-Ying Cui
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China
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AbdelMaseeh M, Stashuk DW. Motor Unit Potential Jitter: A New Measure of Neuromuscular Transmission Instability. IEEE Trans Neural Syst Rehabil Eng 2017; 25:1018-1025. [PMID: 28207399 DOI: 10.1109/tnsre.2017.2666741] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A new measure of neuromuscular transmission instability, motor unit potential (MUP) jitter, is introduced. MUP jitter can be estimated quickly using MUP trains (MUPTs) extracted from electromyographic (EMG) signals acquired using conventional clinical equipment and needle EMG electrodiagnostic protocols. The primary motivation for developing MUP jitter is to avoid the technical demands associated with estimating jitter using conventional single fiber EMG techniques. At the core of the MUP jitter measure is a classifier capable of labeling a set of aligned MUP segments as single fiber MUP segments, i.e., parts of MUPs generated predominantly by a single fiber and not significantly contaminated by contributions from other fibers. For a set of MUPs generated by the same MU, these segments will have varying occurrence times within the MUPs, but will have consistent morphology across the MUPs. Pairs of sets of single fiber MUP segments generated by different fibers of the same MU and tracked across a MUPT can be used to estimate neuromuscular transmission instability. Aligning MUP segments is achieved using dynamic time warping. Results based on 680 simulated MUPTs show that MUP jitter can be estimated with an average error rate as low as 8.9%. Also, one or more sets of single fiber MUP segments can be detected in 85.3% of the studied trains. The analysis for a single MUPT can be completed in 3.6 s on average using a conventional personal computer.
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Sanders DB, Massey JM. Does change in neuromuscular jitter predict or correlate with clinical change in MG? Muscle Nerve 2017; 56:45-50. [DOI: 10.1002/mus.25440] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/28/2016] [Accepted: 10/18/2016] [Indexed: 11/05/2022]
Affiliation(s)
- Donald B. Sanders
- Neuromuscular Section; Department of Neurology, Box 3403, Duke University Medical Center; Durham North Carolina 27710 USA
| | - Janice M. Massey
- Neuromuscular Section; Department of Neurology, Box 3403, Duke University Medical Center; Durham North Carolina 27710 USA
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C.N. Machado F, A. Kouyoumdjian JOÃO, E. Marchiori P. Diagnostic accuracy of concentric needle jitter in myasthenia: Prospective study. Muscle Nerve 2016; 55:190-194. [DOI: 10.1002/mus.25229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/03/2016] [Accepted: 06/24/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Flavia C.N. Machado
- Department of Neurology; Medical School, Universidade de São Paulo; São Paulo Brazil
- Fleury Medicina e Saúde; São Paulo Brazil
| | - JOÃO A. Kouyoumdjian
- Neuromuscular Investigation Laboratory; Faculdade Medicina São José do Rio Preto; São Paulo Brazil
| | - Paulo E. Marchiori
- Department of Neurology; Medical School, Universidade de São Paulo; São Paulo Brazil
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Review of the Diagnostic Challenges of Lambert–Eaton Syndrome Revealed Through Three Case Reports. Can J Neurol Sci 2016; 43:635-47. [DOI: 10.1017/cjn.2016.268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AbstractLambert–Eaton syndrome (LES) is a rare immune-mediated disorder characterized by proximal leg weakness, autonomic symptoms and hypoactive tendon reflexes. The paraneoplastic form is associated with small-cell lung cancer in 50-60% of cases, whereas the remaining cases are found in younger adults with a higher likelihood of coexisting autoimmune disease. The early recognition of LES is crucial for improving clinical outcomes but remains a major challenge. In this review, we analyze the clinical characteristics and diagnostic considerations in treating LES through a series of three case studies, one of which showed definitive response to pyridostigmine and corticosteroid combination therapy, followed by spontaneous remission. Patients were assessed by image-based screening, serological testing and electrophysiological evaluations, which included respiratory and autonomic testing. A better understanding of the common pitfalls in the clinical, serological and neurophysiologic diagnosis of LES through assessment of typical LES dysfunction throughout the nervous system should enable improved recognition and treatment of this syndrome.
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Patel A, Gosk M, Pitt M. The effect of different low-frequency filters on concentric needle jitter in stimulated orbicularis oculi. Muscle Nerve 2016; 54:317-9. [DOI: 10.1002/mus.25178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Anjla Patel
- Department of Clinical Neurophysiology; Great Ormond Street Hospital For Children NHS Foundation Trust; Great Ormond Street London WC1N 3JH UK
- Department of Clinical Neurophysiology; Luton and Dunstable Hospital NHS Foundation Trust; Lewsey Road Luton LU4 0DZ UK
| | - Magdalena Gosk
- Department of Clinical Neurophysiology; Great Ormond Street Hospital For Children NHS Foundation Trust; Great Ormond Street London WC1N 3JH UK
- Department of Paediatrics; Gottfried von Preyer'sches Kinderspital; Vienna Austria
| | - Matthew Pitt
- Department of Clinical Neurophysiology; Great Ormond Street Hospital For Children NHS Foundation Trust; Great Ormond Street London WC1N 3JH UK
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Brown R, Dissanayake KN, Skehel PA, Ribchester RR. Endomicroscopy and electromyography of neuromuscular junctions in situ. Ann Clin Transl Neurol 2014; 1:867-83. [PMID: 25540801 PMCID: PMC4265058 DOI: 10.1002/acn3.124] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 12/12/2022] Open
Abstract
Objective Electromyography (EMG) is used routinely to diagnose neuromuscular dysfunction in a wide range of peripheral neuropathies, myopathies, and neuromuscular degenerative diseases including motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Definitive neurological diagnosis may also be indicated by the analysis of pathological neuromuscular innervation in motor-point biopsies. Our objective in this study was to preempt motor-point biopsy by combining live imaging with electrophysiological analysis of slow degeneration of neuromuscular junctions (NMJs) in vivo. Methods We combined conventional needle electromyography with fiber-optic confocal endomicroscopy (CEM), using an integrated hand-held, 1.5-mm-diameter probe. We utilized as a test bed, various axotomized muscles in the hind limbs of anaesthetized, double-homozygous thy1.2YFP16: WldS mice, which coexpress the Wallerian-degeneration Slow (WldS) protein and yellow fluorescent protein (YFP) in motor neurons. We also tested exogenous vital stains, including Alexa488-α-bungarotoxin; the styryl pyridinium dye 4-Di-2-Asp; and a GFP conjugate of botulinum toxin Type A heavy chain (GFP-HcBoNT/A). Results We show that an integrated EMG/CEM probe is effective in longitudinal evaluation of functional and morphological changes that take place over a 7-day period during axotomy-induced, slow neuromuscular synaptic degeneration. EMG amplitude declined in parallel with overt degeneration of motor nerve terminals. EMG/CEM was safe and effective when nerve terminals and motor endplates were selectively stained with vital dyes. Interpretation Our findings constitute proof-of-concept, based on live imaging in an animal model, that combining EMG/CEM may be useful as a minimally invasive precursor or alternative to motor-point biopsy in neurological diagnosis and for monitoring local administration of potential therapeutics.
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Affiliation(s)
- Rosalind Brown
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh Hugh Robson Building, George Square, Edinburgh, EH8 9XD, United Kingdom
| | - Kosala N Dissanayake
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh Hugh Robson Building, George Square, Edinburgh, EH8 9XD, United Kingdom
| | - Paul A Skehel
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh Hugh Robson Building, George Square, Edinburgh, EH8 9XD, United Kingdom
| | - Richard R Ribchester
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh Hugh Robson Building, George Square, Edinburgh, EH8 9XD, United Kingdom
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