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Pugliese A, Della Marina A, de Paula Estephan E, Zanoteli E, Roos A, Schara-Schmidt U, Hentschel A, Azuma Y, Töpf A, Thompson R, Polavarapu K, Lochmüller H. Mutations in PTPN11 could lead to a congenital myasthenic syndrome phenotype: a Noonan syndrome case series. J Neurol 2024; 271:1331-1341. [PMID: 37923938 DOI: 10.1007/s00415-023-12070-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/12/2023] [Accepted: 10/13/2023] [Indexed: 11/06/2023]
Abstract
The RASopathies are a group of genetic rare diseases caused by mutations affecting genes involved in the RAS/MAPK (RAS-mitogen activated protein kinase) pathway. Among them, PTPN11 pathogenic variants are responsible for approximately 50% of Noonan syndrome (NS) cases and, albeit to a lesser extent, of Leopard syndrome (LPRD1), which present a few overlapping clinical features, such as facial dysmorphism, developmental delay, cardiac defects, and skeletal deformities. Motor impairment and decreased muscle strength have been recently reported. The etiology of the muscle involvement in these disorders is still not clear but probably multifactorial, considering the role of the RAS/MAPK pathway in skeletal muscle development and Acetylcholine Receptors (AChR) clustering at the neuromuscular junction (NMJ). We report, herein, four unrelated children carrying three different heterozygous mutations in the PTPN11 gene. Intriguingly, their phenotypic features first led to a clinical suspicion of congenital myasthenic syndrome (CMS), due to exercise-induced fatigability with a variable degree of muscle weakness, and serum proteomic profiling compatible with a NMJ defect. Moreover, muscle fatigue improved after treatment with CMS-specific medication. Although the link between PTPN11 gene and neuromuscular transmission is unconfirmed, an increasing number of patients with RASopathies are affected by muscle weakness and fatigability. Hence, NS or LPDR1 should be considered in children with suspected CMS but negative genetic workup for known CMS genes or additional symptoms indicative of NS, such as facial dysmorphism or intellectual disability.
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Affiliation(s)
- Alessia Pugliese
- IRCCS Centro Neurolesi "Bonino Pulejo", Messina, Italy
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Rd., Ottawa, ON, K1H 8L1, Canada
| | - Adela Della Marina
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, 45147, Essen, Germany
| | - Eduardo de Paula Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
- Department of Neurological Sciences, Psychiatry, and Medical Psychology, Sao Jose do Rio Preto State Medical School, Sao Jose do Rio Preto, São Paulo, Brazil
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Andreas Roos
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Rd., Ottawa, ON, K1H 8L1, Canada
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, 45147, Essen, Germany
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789, Bochum, Germany
- Leibniz-Institut Für Analytische Wissenschaften-ISAS-e.V., 44227, Dortmund, Germany
| | - Ulrike Schara-Schmidt
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, 45147, Essen, Germany
| | - Andreas Hentschel
- Leibniz-Institut Für Analytische Wissenschaften-ISAS-e.V., 44227, Dortmund, Germany
| | - Yoshiteru Azuma
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, University of Newcastle, Newcastle Upon Tyne, UK
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Rd., Ottawa, ON, K1H 8L1, Canada
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Rd., Ottawa, ON, K1H 8L1, Canada
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Rd., Ottawa, ON, K1H 8L1, Canada.
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada.
- Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada.
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany.
- Centro Nacional de Análisis Genómico (CNAG), Barcelona, Catalonia, Spain.
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ELSAIS A, KERTY E, RUSSELL K, TOSKA K. Does Cardiovascular Autonomic Dysfunction Contribute to Fatigue in Myasthenia Gravis? Physiol Res 2022; 71:79-91. [DOI: 10.33549/physiolres.934660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Myasthenia gravis (MG) is an autoimmune disease characterized by fatigable muscle weakness. Despite full spontaneous or pharmacological remission some MG patients still complain of physical and mental fatigue. Fatigue has been related to autonomic dysregulation. The aim of this study was to assess autonomic responses in a group of MG patients in complete remission but complaining of persistent fatigue. Seventeen well-regulated but persistently fatigued MG patients and 17 individually matched controls underwent echocardiography assessing systolic and diastolic heart function. Beat to beat cardiovascular responses at rest and to 30o head-up tilt, tilt-back, and 2-min static handgrip contraction were recorded. Fatigued MG patients had a statistically significant higher resting HR than their matched controls (p=0.03). The difference in resting heart rate between MG patients not using acetylcholine esterase inhibitors (AChEi) and their matched controls was even more pronounced (p=0.007). The autonomic cardiovascular adjustments to head-up tilt, tilt-back and handgrip contraction were not statistically significant different between patients and controls. We found a higher resting heart rate in all well-regulated but fatigued MG patients compared with controls. The difference was more pronounced between patients not taking AChEi compared to their matched controls. This finding may reflect a disturbed resting sympathovagal balance and this might be a contributing factor to the fatigue symptoms.
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Affiliation(s)
- A ELSAIS
- Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - E KERTY
- Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - K RUSSELL
- Department of Cardiology, Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
| | - K TOSKA
- Faculty of Medicine, Section for Physiology, University of Oslo, Oslo, Norway,
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Bedside and laboratory diagnostic testing in myasthenia. J Neurol 2022; 269:3372-3384. [PMID: 35142871 PMCID: PMC9119875 DOI: 10.1007/s00415-022-10986-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/02/2022]
Abstract
Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are a group of disorders with a well characterised autoimmune or genetic and neurophysiological basis. We reviewed the literature from the last 20 years assessing the utility of various neurophysiological, immunological, provocative and genetic tests in MG and CMS. Diagnostic sensitivity of repetitive nerve stimulation test ranges between 14 and 94% and specificity between 73 and 100%; sensitivity of single-fibre EMG (SFEMG) test ranges between 64 and 100% and specificity between 22 and 100%; anti-acetylcholine receptor (AChR) antibody sensitivity ranges from 13 to 97% and specificity ranges from 95 to 100%. Overall, SFEMG has the highest sensitivity while positive anti-AChR antibodies have the highest specificity. Newer testing strategies that have been investigated over the last couple of decades include ocular vestibular-evoked myogenic potentials, otoacoustic emissions and disease-specific circulating miRNAs in serum for autoimmune myasthenia, as well as next-generation sequencing for genetic testing of CMS. While there has been significant progress in developing newer testing strategies for diagnosing MG and CMS over the last couple of decades, more research is needed to assess the utility of these newer tools regarding their sensitivity and specificity.
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Ma JY, Liu XY, Zhang S, Fan DS. Ultra-early amplitude decrement after repetitive nerve stimulation supports early neuromuscular junction injury in amyotrophic lateral sclerosis: a prospective cross-sectional study. Neural Regen Res 2022; 17:655-660. [PMID: 34380907 PMCID: PMC8504376 DOI: 10.4103/1673-5374.320998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The dying-back hypothesis holds that the damage to neuromuscular junctions and distal axons in amyotrophic lateral sclerosis occurs at the earliest stage of the disease. Previous basic studies have confirmed early damage to neuromuscular junctions, but it is difficult to obtain such evidence directly in clinical practice. In this prospective cross-sectional study, we recruited 22 patients with early amyotrophic lateral sclerosis with disease duration < 12 months and with clinical symptoms limited to the upper limbs. We also recruited 32 healthy controls. Repetitive nerve stimulation was performed, and patients were followed for 12 months. We found a significant change in the response to repetitive nerve stimulation in amyotrophic lateral sclerosis patients without spontaneous electromyographic activity. Patients that were prone to denervation had an increased decrement response of target muscles after repetitive nerve stimulation. These results suggest that changes in response to repetitive nerve stimulation may occur before denervation in amyotrophic lateral sclerosis patients. The damage to lower motor neurons is more obvious in patients with a higher percentage of repetitive never stimulation-related amplitude decrements. This study was approved by the Institutional Ethics Committee of Peking University Third Hospital (approval No. M2017198) on August 24, 2017.
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Affiliation(s)
- Jing-Yue Ma
- Department of Neurology, Peking University Third Hospital; Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
| | - Xiang-Yi Liu
- Department of Neurology, Peking University Third Hospital; Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
| | - Shuo Zhang
- Department of Neurology, Peking University Third Hospital; Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
| | - Dong-Sheng Fan
- Department of Neurology, Peking University Third Hospital; Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
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Classically Described, Paradoxically Underrecognized: A Case of Proximal Weakness, Hyporeflexia/Areflexia, and Dysautonomia. Am J Phys Med Rehabil 2021; 100:e98-e100. [PMID: 33109907 DOI: 10.1097/phm.0000000000001632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
ABSTRACT We present a case of chronic, progressive proximal weakness with dysautonomia and hyporeflexia/areflexia ultimately diagnosed with Lambert-Eaton myasthenic syndrome. An approach to neuroanatomical localization is discussed leading to the appropriate selection of electrodiagnostic studies. The electrophysiologic triad of Lambert-Eaton myasthenic syndrome is demonstrated with diffusely reduced motor amplitudes, decrement with low-frequency repetitive nerve stimulation, and increment of motor amplitudes after maximum voluntary contraction. Subsequent serologic testing for P/Q-type voltage-gated calcium channel antibodies are markedly elevated. We highlight the clinical features and pitfalls of examining a patient with Lambert-Eaton myasthenic syndrome when suspecting this challenging diagnosis. The neurophysiological underpinning of the electrodiagnostic results is explained, and the diagnostic utility of single-fiber electromyography is briefly discussed.
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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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Liu Z, Zhu Y, Yuan Y, Yang L, Wang K, Wang M, Yang X, Wu X, Tian X, Zhang R, Shen B, Luo H, Feng H, Feng S, Ke Z. 3D DenseNet Deep Learning Based Preoperative Computed Tomography for Detecting Myasthenia Gravis in Patients With Thymoma. Front Oncol 2021; 11:631964. [PMID: 34026611 PMCID: PMC8132943 DOI: 10.3389/fonc.2021.631964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 04/13/2021] [Indexed: 11/13/2022] Open
Abstract
Background Myasthenia gravis (MG) is the most common paraneoplastic syndromes of thymoma and closely related to thymus abnormalities. Timely detecting of the risk of MG would benefit clinical management and treatment decision for patients with thymoma. Herein, we developed a 3D DenseNet deep learning (DL) model based on preoperative computed tomography (CT) as a non-invasive method to detect MG in thymoma patients. Methods A large cohort of 230 thymoma patients in a hospital affiliated with a medical school were enrolled. 182 thymoma patients (81 with MG, 101 without MG) were used for training and model building. 48 cases from another hospital were used for external validation. A 3D-DenseNet-DL model and five radiomic models were performed to detect MG in thymoma patients. A comprehensive analysis by integrating machine learning and semantic CT image features, named 3D-DenseNet-DL-based multi-model, was also performed to establish a more effective prediction model. Findings By elaborately comparing the prediction efficacy, the 3D-DenseNet-DL effectively identified MG patients and was superior to other five radiomic models, with a mean area under ROC curve (AUC), accuracy, sensitivity, and specificity of 0.734, 0.724, 0.787, and 0.672, respectively. The effectiveness of the 3D-DenseNet-DL-based multi-model was further improved as evidenced by the following metrics: AUC 0.766, accuracy 0.790, sensitivity 0.739, and specificity 0.801. External verification results confirmed the feasibility of this DL-based multi-model with metrics: AUC 0.730, accuracy 0.732, sensitivity 0.700, and specificity 0.690, respectively. Interpretation Our 3D-DenseNet-DL model can effectively detect MG in patients with thymoma based on preoperative CT imaging. This model may serve as a supplement to the conventional diagnostic criteria for identifying thymoma associated MG.
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Affiliation(s)
- Zhenguo Liu
- Department of Thoracic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ying Zhu
- Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Institution of Precision Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yujie Yuan
- Center of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Lei Yang
- Department of Thoracic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Kefeng Wang
- Department of Thoracic Surgery, The Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Minghui Wang
- Department of Thoracic Surgery, The Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xiaoyu Yang
- Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xi Wu
- Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xi Tian
- Advanced Institute, Infervision, Beijing, China
| | | | - Bingqi Shen
- Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Honghe Luo
- Department of Thoracic Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Huiyu Feng
- Department of Neurology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Shiting Feng
- Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zunfu Ke
- Institution of Precision Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Department of Pathology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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Lamb CJ, Rubin DI. Sensitivity and specificity of repetitive nerve stimulation with lower cutoffs for abnormal decrement in myasthenia gravis. Muscle Nerve 2020; 62:381-385. [PMID: 32530515 DOI: 10.1002/mus.26999] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/04/2020] [Accepted: 06/07/2020] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The sensitivity of repetitive nerve stimulation (RNS) in myasthenia gravis (MG) is dependent on the cutoff for abnormal decrement. METHODS RNS data of adults with and without MG from 2014 to 2017 were reviewed retrospectively. The maximum reliable RNS amplitude/area decrement before and after exercise from facial, spinal accessory (SA), ulnar, and fibular nerves was recorded. Sensitivity/specificity using 5%, 7%, and 10% cutoffs were calculated. RESULTS Seventy-nine of 141 patients had MG (46 generalized, 21 ocular, 12 bulbar). A total of 608 unique RNS recordings were analyzed. Overall RNS sensitivity/specificity at ≥5%, ≥7%, and ≥10% amplitude cutoffs were as follows: SA, 65.6%/86.3%, 49.2%/94.1%, and 29.5%/96.1%; facial, 51.0%/82.5%, 43.1%/95.0%, and 37.3%/100%; ulnar, 43.6%/100%, 41.0%/100%, and 41.0%/100%; and fibular, 52.6%/89.5%, 42.1%/94.7%, and 42.1%/100%. DISCUSSION Lowering amplitude cutoff from 10% to 7% increased or maintained sensitivity with little loss in specificity. Post-exercise and area analysis resulted in increased sensitivity in some circumstances.
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Affiliation(s)
| | - Devon I Rubin
- Department of Neurology, Mayo Clinic, Jacksonville, Florida, USA
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Abstract
PURPOSE OF REVIEW Myasthenia gravis (MG) is an autoimmune neuromuscular disease that causes fluctuating weakness in ocular, bulbar, and limb muscles and can, in 15% of cases, cause myasthenic crisis, a neurologic emergency characterized by respiratory failure. Although infrequent, MG needs to be promptly recognized and treated because the potential for improvement and remission is very high. The diagnosis of MG can be challenging and delayed because of the fluctuating nature of muscle weakness and the overlap of signs and symptoms with other neuromuscular diseases.This article reviews the importance of prompt recognition of the typical signs and symptoms, best tests to confirm the diagnosis, currently available acute and chronic treatment modalities, the role of thymectomy, and the natural history of the disease. Special consideration related to the diagnosis and management in women during pregnancy and in children will also be reviewed. This article also includes an overview of congenital myasthenic syndromes. RECENT FINDINGS Recent significant efforts in standardizing and improving the care of patients with MG have occurred, as well as new momentum in developing new drugs for patients with MG who do not adequately respond to currently available treatments. The number of clinical trials and drugs in development for MG is steadily increasing. Eculizumab has been recently approved by the US Food and Drug Administration (FDA) for adult patients with generalized MG who are acetylcholine receptor-antibody positive, based on the REGAIN (Safety and Efficacy of Eculizumab in Refractory Generalized Myasthenia Gravis) study, a phase 3, randomized, double-blind, placebo-controlled, multicenter trial. An international, multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone has demonstrated that thymectomy improves clinical outcome in patients with nonthymomatous MG. Clinical care guidelines have been published, and the recommendations for clinical research standards and the Myasthenia Gravis Foundation of America MGFA clinical classification published in 2000 have become widely accepted by the clinical and research community of MG experts. SUMMARY MG is a highly treatable disease with many effective treatment modalities available and with a natural history that continues to improve thanks to better diagnostic tests and effective drugs. The diagnosis and management of patients affected by MG can be highly rewarding for any neurologist as most patients are able to live normal lives if treated appropriately. Nevertheless, future research is needed to address unresolved clinical issues, such as when and how to discontinue immunosuppressive medications in patients in remission, the role and timing of thymectomy in children, and better treatment options for refractory patients.
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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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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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Palpebral portion of the orbicularis oculi muscle to repetitive nerve stimulation testing: A potential assessment indicator in patients with generalized myasthenia gravis. J Clin Neurosci 2017; 48:238-242. [PMID: 29239825 DOI: 10.1016/j.jocn.2017.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 11/15/2017] [Indexed: 11/20/2022]
Abstract
Repetitive nerve stimulation (RNS) is a valuable diagnostic method for myasthenia gravis (MG). However, its association with clinical severity was scarcely studied. We reviewed medical records and retrospectively enrolled 121 generalized MG patients. Sensitivity of different muscles to RNS and clinical scoring systems was evaluated. RNS testing revealed facial muscles have the highest positive rate, followed by proximal muscles and distal muscles, with the palpebral portion of the orbicularis oculi muscle most sensitive. Amplitude decrement of compound muscle action potential (CMAP) in the palpebral portion of the orbicularis oculi muscle is related to quantitative myasthenia gravis (QMG) scores, MG-specific manual muscle testing (MMT) scores and myasthenia gravis-related activities of daily living (MG-ADL) scores. We suggest that RNS testing of the palpebral portion of the orbicularis oculi muscle is a potential assessment indicator in patients with generalized MG.
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Utility of repetitive nerve stimulation test for ALS diagnosis. Clin Neurophysiol 2017; 128:823-829. [DOI: 10.1016/j.clinph.2017.02.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 02/11/2017] [Accepted: 02/26/2017] [Indexed: 11/23/2022]
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Bou Ali H, Salort-Campana E, Grapperon AM, Gallard J, Franques J, Sevy A, Delmont E, Verschueren A, Pouget J, Attarian S. New strategy for improving the diagnostic sensitivity of repetitive nerve stimulation in myasthenia gravis. Muscle Nerve 2017; 55:532-538. [DOI: 10.1002/mus.25374] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Hanna Bou Ali
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- INSERM U910 Aix-Marseille University; Marseille France
| | - Emmanuelle Salort-Campana
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- INSERM U910 Aix-Marseille University; Marseille France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
| | - Aude Marie Grapperon
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- INSERM U910 Aix-Marseille University; Marseille France
| | - Julien Gallard
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
| | - Jerome Franques
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
| | - Amandine Sevy
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
| | - Emilien Delmont
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
| | - Annie Verschueren
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
| | - Jean Pouget
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- INSERM U910 Aix-Marseille University; Marseille France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
| | - Shahram Attarian
- Reference Center for Neuromuscular Disorders and ALS; Timone University Hospital; 264 rue Saint-Pierre, Marseille Cedex 05 13385 France
- INSERM U910 Aix-Marseille University; Marseille France
- FILNEMUS, Filière nationale des maladies neuromusculaires; Marseille France
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Abraham A, Alabdali M, Alsulaiman A, Breiner A, Barnett C, Katzberg HD, Lovblom LE, Bril V. Repetitive nerve stimulation cutoff values for the diagnosis of myasthenia gravis. Muscle Nerve 2016; 55:166-170. [DOI: 10.1002/mus.25214] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/05/2016] [Accepted: 06/07/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Alon Abraham
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine; University Health Network; Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309 Toronto Ontario Canada M5G 2C4
| | - Majed Alabdali
- Department of Neurology; King Fahad Hospital of the University, University of Dammam; Dammam Saudi Arabia
| | - Abdulla Alsulaiman
- Department of Neurology; King Fahad Hospital of the University, University of Dammam; Dammam Saudi Arabia
| | - Ari Breiner
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine; University Health Network; Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309 Toronto Ontario Canada M5G 2C4
| | - Carolina Barnett
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine; University Health Network; Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309 Toronto Ontario Canada M5G 2C4
| | - Hans D. Katzberg
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine; University Health Network; Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309 Toronto Ontario Canada M5G 2C4
| | - Leif E. Lovblom
- Division of Endocrinology and Metabolism, Department of Medicine, Mount Sinai, Hospital and Lunenfeld Tanenbaum Research Institute; University of Toronto; Toronto Canada
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine; University Health Network; Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309 Toronto Ontario Canada M5G 2C4
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Pitt MC, Jabre JF. Determining jitter values in the very young by use of the e‐norms methodology. Muscle Nerve 2016; 55:51-54. [DOI: 10.1002/mus.25191] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 04/25/2016] [Accepted: 05/13/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Matthew C. Pitt
- Department of Clinical NeurophysiologyGreat Ormond Street Hospital for Children NHS Foundation TrustLondonWC1N 3JH UK
| | - Joe F. Jabre
- Department of Neurology, David Geffen School of MedicineUniversity of California Los AngelesLos Angeles California USA
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Abraham A, Alabdali M, Alsulaiman A, Breiner A, Barnett C, Katzberg HD, Bril V. Repetitive facial nerve stimulation in myasthenia gravis 1min after muscle activation is inferior to testing a second muscle at rest. Clin Neurophysiol 2016; 127:3294-7. [DOI: 10.1016/j.clinph.2016.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 07/11/2016] [Accepted: 08/07/2016] [Indexed: 11/16/2022]
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Silva A, Maduwage K, Sedgwick M, Pilapitiya S, Weerawansa P, Dahanayaka NJ, Buckley NA, Siribaddana S, Isbister GK. Neurotoxicity in Russell's viper (Daboia russelii) envenoming in Sri Lanka: a clinical and neurophysiological study. Clin Toxicol (Phila) 2016; 54:411-9. [PMID: 26923566 DOI: 10.3109/15563650.2016.1143556] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 01/08/2016] [Accepted: 01/13/2016] [Indexed: 11/13/2022]
Abstract
CONTEXT Russell's viper is more medically important than any other Asian snake, due to number of envenoming's and fatalities. Russell's viper populations in South India and Sri Lanka (Daboia russelii) cause unique neuromuscular paralysis not seen in other Russell's vipers. OBJECTIVE To investigate the time course and severity of neuromuscular dysfunction in definite Russell's viper bites, including antivenom response. METHODOLOGY We prospectively enrolled all patients (>16 years) presenting with Russell's viper bites over 14 months. Cases were confirmed by snake identification and/or enzyme immunoassay. All patients had serial neurological examinations and in some, single fibre electromyography (sfEMG) of the orbicularis oculi was performed. RESULTS 245 definite Russell's viper bite patients (median age: 41 years; 171 males) presented a median 2.5 h (interquartile range: 1.75-4.0 h) post-bite. All but one had local envenoming and 199 (78%) had systemic envenoming: coagulopathy in 166 (68%), neurotoxicity in 130 (53%), and oliguria in 19 (8%). Neurotoxicity was characterised by ptosis (100%), blurred vision (93%), and ophthalmoplegia (90%) with weak extraocular movements, strabismus, and diplopia. Neurotoxicity developed within 8 h post-bite in all patients. No bulbar, respiratory or limb muscle weakness occurred. Neurotoxicity was associated with bites by larger snakes (p < 0.0001) and higher peak serum venom concentrations (p = 0.0025). Antivenom immediately decreased unbound venom in blood. Of 52 patients without neurotoxicity when they received antivenom, 31 developed neurotoxicity. sfEMG in 27 patients with neurotoxicity and 23 without had slightly elevated median jitter on day 1 compared to 29 normal subjects but normalised thereafter. Neurological features resolved in 80% of patients by day 3 with ptosis and weak eye movements resolving last. No clinical or neurophysiological abnormality was detected at 6 weeks or 6 months. CONCLUSION Sri Lankan Russell's viper envenoming causes mild neuromuscular dysfunction with no long-term effects. Indian polyvalent antivenom effectively binds free venom in blood but does not reverse neurotoxicity.
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Affiliation(s)
- Anjana Silva
- a Monash Venom Group, Department of Pharmacology , Monash University , Clayton , VIC , Australia
- b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka
- c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka
| | - Kalana Maduwage
- c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka
- d Clinical Toxicology Research Group , University of Newcastle , Callaghan , NSW , Australia
| | - Michael Sedgwick
- c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka
| | - Senaka Pilapitiya
- b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka
| | - Prasanna Weerawansa
- b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka
| | - Niroshana J Dahanayaka
- b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka
| | - Nicholas A Buckley
- c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka
- e Clinical Pharmacology , University of Sydney , Sydney , NSW , Australia
| | - Sisira Siribaddana
- b Faculty of Medicine and Allied Sciences , Rajarata University of Sri Lanka , Saliyapura , Sri Lanka
| | - Geoffrey K Isbister
- c South Asian Clinical Toxicology Research Collaboration , University of Peradeniya, Peradeniya , Sri Lanka
- d Clinical Toxicology Research Group , University of Newcastle , Callaghan , NSW , Australia
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Lee HS, Lee HS, Lee HE, Bae MK, Chung KY, Shin HY, Choi YC, Kim SM. Predictive factors for myasthenic crisis after videoscopic thymectomy in patients with myasthenia gravis. Muscle Nerve 2015; 52:216-20. [DOI: 10.1002/mus.24531] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Hyung Seok Lee
- Department of Neurology; Yonsei University College of Medicine; 50 Yonsei-ro, Seodaemun-gu Seoul 120-752 Republic of Korea
| | - Hye Sun Lee
- Department of Biostatistics; Yonsei University College of Medicine; Seoul Republic of Korea
| | - Hyo Eun Lee
- Department of Neurology; Yonsei University College of Medicine; 50 Yonsei-ro, Seodaemun-gu Seoul 120-752 Republic of Korea
| | - Mi Kyung Bae
- Department of Thoracic and Cardiovascular Surgery; Yonsei University College of Medicine; Seoul Republic of Korea
| | - Kyung Young Chung
- Department of Thoracic and Cardiovascular Surgery; Yonsei University College of Medicine; Seoul Republic of Korea
| | - Ha Young Shin
- Department of Neurology; Yonsei University College of Medicine; 50 Yonsei-ro, Seodaemun-gu Seoul 120-752 Republic of Korea
| | - Young-Chul Choi
- Department of Neurology; Yonsei University College of Medicine; 50 Yonsei-ro, Seodaemun-gu Seoul 120-752 Republic of Korea
| | - Seung Min Kim
- Department of Neurology; Yonsei University College of Medicine; 50 Yonsei-ro, Seodaemun-gu Seoul 120-752 Republic of Korea
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Papathanasiou ES, Zamba-Papanicolaou E. Single fiber electromyography: What type of needle should I use? Clin Neurophysiol 2013; 124:2077-8. [DOI: 10.1016/j.clinph.2013.05.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 05/25/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
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Cherian A, Baheti NN, Iype T. Electrophysiological study in neuromuscular junction disorders. Ann Indian Acad Neurol 2013; 16:34-41. [PMID: 23661960 PMCID: PMC3644779 DOI: 10.4103/0972-2327.107690] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/13/2011] [Accepted: 07/01/2012] [Indexed: 11/20/2022] Open
Abstract
This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG) helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS). SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.
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Affiliation(s)
- Ajith Cherian
- Department of Neurology, Government Medical College, Trivandrum, Kerala, India
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Lacomis D. Electrophysiology of neuromuscular disorders in critical illness. Muscle Nerve 2013; 47:452-63. [PMID: 23386582 DOI: 10.1002/mus.23615] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2012] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Neuromuscular disorders, predominantly critical illness myopathy (CIM) and critical illness polyneuropathy (CIP) occur in approximately one-third of patients in intensive care units. The aim of this study was to review the important role of electrophysiology in this setting. RESULTS In CIM, sarcolemmal inexcitability causes low amplitude compound muscle action potentials (CMAPs) that may have prolonged durations. Needle electrode examination usually reveals early recruitment of short duration motor unit potentials, often with fibrillation potentials. In CIP, the findings are usually those of a generalized axonal sensorimotor polyneuropathy. Direct muscle stimulation aids in differentiating CIP and CIM and in identifying mixed disorders along with other electrodiagnostic and histopathologic studies. Identifying evolving reductions in fibular CMAP amplitudes in intensive care unit (ICU) patients predicts development of neuromuscular weakness. CONCLUSIONS Knowledge of the various neuromuscular disorders in critically ill patients, their risk factors, and associated electrodiagnostic findings can lead to development of a rational approach to diagnosis of the cause of neuromuscular weakness in ICU patients.
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Affiliation(s)
- David Lacomis
- Department of Neurology, University of Pittsburgh School of Medicine, 200 Lothrop Street, F878, Pittsburgh, Pennsylvania 15213, USA.
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Papathanasiou ES, Zamba-Papanicolaou E. A comparison between disposable and reusable single fiber needle electrodes in relation to stimulated single fiber studies. Clin Neurophysiol 2012; 123:1437-9. [DOI: 10.1016/j.clinph.2011.10.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 10/04/2011] [Accepted: 10/23/2011] [Indexed: 11/30/2022]
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Decremental responses to repetitive nerve stimulation (RNS) in motor neuron disease. Clin Neurophysiol 2011; 122:2530-6. [DOI: 10.1016/j.clinph.2011.05.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Revised: 05/24/2011] [Accepted: 05/26/2011] [Indexed: 11/21/2022]
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Nicolle MW. Lambert–Eaton Myasthenic Syndrome. Neuromuscul Disord 2011. [DOI: 10.1002/9781119973331.ch18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Symonette CJ, Doherty TJ. Response. Muscle Nerve 2011. [DOI: 10.1002/mus.21861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Symonette CJ, Watson BV, Koopman WJ, Nicolle MW, Doherty TJ. Muscle strength and fatigue in patients with generalized myasthenia gravis. Muscle Nerve 2009; 41:362-9. [DOI: 10.1002/mus.21493] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Rigoard P, Lapierre F. Rappels sur le nerf périphérique. Neurochirurgie 2009; 55:360-74. [DOI: 10.1016/j.neuchi.2009.08.156] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 12/20/2022]
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Rigoard P, Buffenoir K, Bauche S, Fares M, Koenig J, Hantaï D, Giot JP, Seguin F, Huze C, Schaeffer L, Maixent JM. [Tools and techniques dedicated to neuromuscular junction observation]. Neurochirurgie 2009; 55 Suppl 1:S43-8. [PMID: 19232651 DOI: 10.1016/j.neuchi.2008.03.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 03/24/2008] [Indexed: 11/28/2022]
Abstract
A few decades ago, the neuromuscular junction (NMJ) concept was reduced to two elements: the nerve ending and the facing muscular zone. This description has since changed substantially based on recent studies conducted on the molecular aspects of neurotransmission. The aim of this paper is to provide a synthetic view of the major morphological, molecular and electrophysiological tools used in the analysis of NMJ architecture and its functional characterization.
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Affiliation(s)
- P Rigoard
- Service de neurochirurgie, CHU La-Milétrie, BP 577, 2, rue de La-Milétrie, 86021 Poitiers cedex, France.
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Differential Orbicularis Oculi Involvement in Neuromuscular Junction Dysfunction. J Clin Neurophysiol 2008; 25:293-8. [DOI: 10.1097/wnp.0b013e3181879d70] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Electrodiagnostic Medicine Skills Competency in Physical Medicine and Rehabilitation Residents. Am J Phys Med Rehabil 2008; 87:654-65. [DOI: 10.1097/phm.0b013e31816de0f2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Grommes C, Preston DC, Al-Kadhimi Z, Alshekhlee A. Lambert–Eaton syndrome with large-cell neuroendocrine carcinoma of the lung. Muscle Nerve 2008; 37:786-9. [DOI: 10.1002/mus.21032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
OBJECTIVE To describe the clinical presentation, diagnosis, and treatment of myasthenia gravis (MG) while emphasizing the important role of the pharmacist. DATA SOURCES English-language articles from MEDLINE pertinent to MG study selection and data extraction: All relevant publications addressing MG management were considered, including prospective comparative trials, epidemiological studies, guideline statements, review articles, and editorials. Particular focus occurred on primary literature published after 1976, but limited amount(s) existed. The American Autoimmune Related Diseases Association, Autoimmune Information Network, Inc., Myasthenia Gravis Foundation of America, Inc. (MGFA), National Institute of Neurological Disorders and Stroke, and National Organization for Rare Disorders. DATA SYNTHESIS MG is an autoimmune disorder involving the neuromuscular junction causing characteristic weakness in voluntary muscle groups. To determine appropriate pharmacotherapy, one must characterize the disease based on the degree of function and region of muscles affected. MGFA established a classification system of the disease in order to assess severity. Contemporary treatments include cholinesterase inhibitors, corticosteroids, immodulating/immunosuppressive therapy, intravenous immune globulin, plasmapheresis, and thymectomy. Because of the lack of double-blind, placebo-controlled, randomized clinical trials, treatments are less evidence-based than many other disease states. Clinicians should be aware of the different treatments and recognize the best treatment for the individual. CONCLUSIONS The diagnosis and treatment of MG is a therapeutic challenge. Pharmacists play an essential role in the care of these patients by avoiding drugs that exacerbate the disease, promoting optimal pharmacotherapy, monitoring pharmacotherapy, and ensuring compliance with prescribed medications.
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Affiliation(s)
- Stephanie E Matney
- Virginia Commonwealth University/Medical College of Virginia, School of Pharmacy, Richmond, Virginia, USA
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Dokai H, Nomura Y, Fujikawa Y, Nihei K, Segawa M, Shinomiya N. A study of the factors inducing the development of childhood-onset myasthenia gravis using CDR3 spectratyping analysis of the TCR repertoire. J Neuroimmunol 2007; 187:192-200. [PMID: 17560663 DOI: 10.1016/j.jneuroim.2007.04.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 04/17/2007] [Accepted: 04/30/2007] [Indexed: 11/23/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disease. AChR-specific autologous helper T (Th) cells are essential to the pathogenesis of MG. Factors correlated with the development of childhood-onset MG are unknown. In longitudinal studies, we found TCR Vbeta 2/5.1/6/7 usage in the development or relapse phases, but not in the remission phase. We also found that TCR Vbeta 8/9/13.1/15/18/20 usage persisted. The polyclonally expanded TCR Vbeta 2/5.1/6/7 by CDR3 spectratyping was found to be associated with the development of disease. These data suggest that in patients with childhood-onset MG, stimuli such as superantigens induced by a preceding infection, which cause development of the polyclonal pattern in TCR Vbeta families, play an important role in the development of the disease.
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Affiliation(s)
- Hidenori Dokai
- Toho University Medical Center, Ohashi Hospital, 2nd Department of Pediatrics, 2-17-6 Ohashi Meguro-ku, Tokyo 153-8515, Japan.
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Baslo MB, Deymeer F, Serdaroglu P, Parman Y, Ozdemir C, Cuttini M. Decrement pattern in Lambert–Eaton myasthenic syndrome is different from myasthenia gravis. Neuromuscul Disord 2006; 16:454-8. [PMID: 16806929 DOI: 10.1016/j.nmd.2006.05.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 05/02/2006] [Accepted: 05/08/2006] [Indexed: 10/24/2022]
Abstract
The decrement pattern at low rates of repetitive nerve stimulation in myasthenia gravis (MG) is characterized by a decrease of compound muscle action potential size within the first 4-5 responses. With subsequent stimuli, compound muscle action potential size either increases or does not change. Following an observation that the pattern of decrement might be different in patients with Lambert-Eaton myasthenic syndrome (LEMS), we retrospectively studied traces from eight LEMS patients and 14 patients with seropositive generalized MG, calculating decrement percent from first to fourth and from first to ninth compound muscle action potential. In the LEMS patients, compound muscle action potential amplitude decreased progressively from first to ninth stimulus at 2, 3 or 5Hz in all traces but one. In contrast, MG patients demonstrated the expected improvement after the initial decrement in all traces except one. In the evaluation of patients suspected of having myasthenia gravis, the finding of progressive decrement pattern at low rates of repetitive nerve stimulation may alert the electromyographer to the possibility of Lambert-Eaton syndrome and prompt the performance of further electrodiagnostic tests.
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Affiliation(s)
- M Baris Baslo
- Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, 34390 Capa, Istanbul, Turkey
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Vaidya H. Case of the month: Unusual presentation of myasthenia gravis with acute respiratory failure in the emergency room. Emerg Med J 2006; 23:410-3. [PMID: 16627853 PMCID: PMC2564100 DOI: 10.1136/emj.2005.030429] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A 21 year old woman with no past medical history presented to the emergency room (ER) with signs and symptoms of sepsis and subsequently went into acute respiratory failure. She was found to have myasthenia gravis which was exacerbated by the infection. This report highlights the need to consider myasthenia gravis in the differential diagnosis of an otherwise unexplained respiratory failure in the critical care setting.
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Affiliation(s)
- H Vaidya
- Pulmonary and Critical Care Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Costa J, Evangelista T, Conceição I, de Carvalho M. Repetitive nerve stimulation in myasthenia gravis--relative sensitivity of different muscles. Clin Neurophysiol 2005; 115:2776-82. [PMID: 15546785 DOI: 10.1016/j.clinph.2004.05.024] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2004] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To correlate repetitive nerve stimulation (RNS) decrement in different muscles with the predominant clinical presentation in myasthenia gravis (MG), and to study single fibre EMG (SFEMG) sensitivity in ocular MG. METHODS Sixty-nine, untreated, consecutive patients suspected for MG were observed prospectively for a minimum of 6 months. Those who improved on medical treatment were diagnosed as MG. The others, in whom the neurophysiological studies were normal and that did not improve on medical treatment served as a control group, from which normative data for RNS and SFEMG was obtained. The MG patients were further classified in 3 subgroups according to the predominant clinical presentation: group I (ocular); group b (bulbar); and group a (axial). We performed RNS in nasalis, trapezius, anconeus, and abductor digiti minimi. All patients with ocular MG underwent jitter determination of the orbicularis oculi muscle. RESULTS Thirty-seven patients were diagnosed as MG (group I, 15; group b, 13; group a, 9). In group I, RNS was abnormal in 33% of the patients. RNS studies disclosed at least one abnormal muscle response in every patient in groups a and b. Trapezius was significantly more sensitive in group a, and anconeus and nasalis in group b (P < 0.01). Jitter was abnormal in all patients in group I, and the most sensitive parameter was an increased number of unstable pairs, 100%. CONCLUSIONS Based on these observations, we recommend that a shoulder muscle, as the trapezius, should be studied first in the limb-axial presentation of MG, and the anconeus-nasalis muscles in predominant bulbar MG. In ocular MG, RNS is not sensitive and jitter should be performed in facial muscles. SIGNIFICANCE This paper shows the unequal sensitivity of several muscles to RNS in different forms of MG.
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Affiliation(s)
- João Costa
- Department of Neurology, Hospital de Santa Maria, Av. Prof. Egas Moniz, 1649 Lisbon, Portugal
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Kuntzer T, Michel P. Muscle membrane polarisation after provocative tests, and after cooling: the normal CMAP changes to be expected. Clin Neurophysiol 2004; 115:1457-63. [PMID: 15134715 DOI: 10.1016/j.clinph.2004.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2004] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To know the range of changes of compound muscle action potentials (CMAPs) in the muscles innervated by the ulnar nerve after diverse provocative tests, 14 healthy patients were studied with the same protocol. METHODS CMAPs were measured at rest, just after a short exercise test (SET), during short 5 and 10c/s repetitive nerve stimulation (RNS) trains, at approximately 32 and approximately 20 degrees C. RESULTS At 32 degrees C, the SET induced a significant but transient enlargement of the CMAPs (amplitude increased by 8.3%, duration decreased by 9%) that was only partially reproduced by RNS trains, except for a significant shortening of the CMAPs at 10c/s. At 20 degrees C without exercise, CMAPs increased significantly by approximately 30% in amplitude, duration and area, and after the SET the inverse of what has been seen at 32 degrees C was observed (amplitude decreased by 1.7% and duration increased by 9%). RNS at 20 degrees C produced a marked interpatient heterogeneity except for a significant shortening of the CMAPs at 10c/s. In one pure autonomic failure patient, the infusion of norepinephrine induced potentiation of the responses at rest and a decrease in the expected changes after provocative tests. CONCLUSIONS CMAP amplitude and duration are significantly modified just after the SET at 32 degrees C, at rest at 20 degrees C and after RNS at 10c/s but not at 5c/s. Although providing indirect evidence, these findings indicate that provocative tests make the muscle membrane hyperexcitable by the way of a direct influence on the electrical events and by an indirect local catecholamine spillover.
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Affiliation(s)
- Thierry Kuntzer
- Service de Neurologie, Centre Hospitalier Universitaire Vaudois, rue du Bugnon, CHUV BH 07/306, 1011 Lausanne, Switzerland.
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Shinomiya N, Nomura Y, Segawa M. A variant of childhood-onset myasthenia gravis: HLA typing and clinical characteristics in Japan. Clin Immunol 2004; 110:154-8. [PMID: 15003812 DOI: 10.1016/j.clim.2003.10.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Revised: 10/07/2003] [Accepted: 10/20/2003] [Indexed: 10/26/2022]
Abstract
To investigate the correlation between clinical features and HLA DR/DQ genetic variability in myasthenia gravis (MG), we evaluated HLA DR/DQ allele frequencies in 87 Japanese patients with childhood-onset disease. HLA genotypes DRB1*1302/DQA1*0102/DQB1*0604 and DRB1*0901/DQA1*0301/DQB1*0303 were significantly higher in patients than in healthy controls (P(c) < 0.0001, RR = 5.5; P(c) < 0.0001, RR = 8.5, for two genotypes, respectively). Patients who had a significantly higher likelihood of the HLA types DRB1*1302/DQA1*0102/DQB1*0604 or DRB1*0901/DQA1*0301/DQB1*0303 belonged to the latent general type (LG) of MG; this is clinically ocular type, but shows myasthenic electromyographic findings in extremity muscles. The LG type of MG was observed in 78% of patients exhibiting the clinically ocular type; this group comprised approximately 75% of patients with childhood-onset MG. These date suggest that LG type of MG may present a particular subset of childhood-onset MG, which is associated with the specific HLA subtypes DRB1*1302/DQA1*0102/DQB1*0604 and DRB1*0901/DQA1*0301/DQB1*0303.
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Affiliation(s)
- Noriaki Shinomiya
- Second Department of Pediatrics, Ohashi Hospital, Toho University School of Medicine, Meguro, Tokyo, Japan.
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Abstract
Myasthenia gravis (MG) is a syndrome of fluctuating skeletal muscle weakness that worsens with use and improves with rest. Eye, facial, oropharyngeal, axial, and limb muscles may be involved in varying combinations and degrees of severity. Its etiology is heterogeneous, divided initially between those rare congenital myasthenic syndromes, which are genetic, and the bulk of MG, which is acquired and autoimmune. The autoimmune conditions are divided in turn between those that possess measurable serum acetylcholine receptor (AChR) antibodies and a smaller group that does not. The latter group includes those MG patients who have serum antibodies to muscle-specific tyrosine kinase (MuSK). Therapeutic considerations differ for early-onset MG, late-onset MG, and MG associated with the presence of a thymoma. Most MG patients can be treated effectively, but there is still a need for more specific immunological approaches.
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Affiliation(s)
- John C Keesey
- Department of Neurology, UCLA School of Medicine, Los Angeles, California, USA.
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Valls-Canals J, Povedano M, Montero J, Pradas J. Stimulated single-fiber EMG of the frontalis and orbicularis oculi muscles in ocular myasthenia gravis. Muscle Nerve 2003; 28:501-3. [PMID: 14506723 DOI: 10.1002/mus.10426] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We performed single-fiber electromyography by axonal stimulation (stimulated SFEMG) of the frontalis and orbicularis oculi muscles of 20 patients with ocular myasthenia gravis (OM) and 46 controls. In controls, mean consecutive differences (MCD) ranged from 5 to 55 micros (average, 14.7 +/- 2.8 micros) in the frontalis and from 4 to 56 micros (average, 12.56 +/- 2.19 micros) in orbicularis oculi. The mean MCD of individual muscle potentials (MPs) was 14.6 +/- 6.8 micros in frontalis and 12.68 +/- 6.10 micros in orbicularis oculi. In the OM patients, the mean MCD was 43.85 +/- 25.18 micros in the frontalis and 69.85 +/- 29.55 micros in orbicularis oculi (P < 0.0001), and the number of MPs with altered MCD was 7.15 +/- 4.66 (range, 1-18) and 12.65 +/- 4.90 (range, 6-21), respectively (P < 0.0001). We conclude that stimulated SFEMG of the orbicularis oculi muscle is more sensitive for the diagnosis of OM than of the frontalis muscle.
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Affiliation(s)
- J Valls-Canals
- Unitat de Neuromuscular i Electromiografia, Institut Universitari Dexeus, Calatrava 83, 6 planta, 08017 Barcelona, Spain.
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Abstract
Repetitive nerve stimulation and exercise testing are useful in the evaluation of patients with suspected disorders of the NMJ and muscle membrane excitability when performed with close attention to technical factors. They can be very helpful in the diagnosis of myasthenia gravis. Lambert-Eaton myasthenic syndrome, and botulism, as well as rare disorders of skeletal muscle membrane excitability, including paramyotonia congenita, myotonia congenita, myotonic dystrophy, and the periodic paralyses.
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Affiliation(s)
- Barbara E Shapiro
- Department of Neurology, University Hospitals of Cleveland, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106-5098, USA.
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Abstract
Single-fiber EMG is a technique introduced in 1963 by Stålberg and Ekstedt for recording single muscle fiber action potentials by means of a specially constructed needle with a 25-microm recording surface. The needle is positioned in the muscle to record from two or more time-locked potentials belonging to the same motor unit. Jitter is the variability in the arrival time of action potentials to the recording electrode between consecutive discharges. This variability reflects end-plate conduction and is measured along with fiber density, which is the average number of fibers belonging to the same motor unit that is in the recording area. An abnormal test is one in which more than 10%, or the mean, of 20 fiber pairs has increased jitter when compared with normal reference values. Increased fiber density is seen with reinnervation. Single-fiber EMG is more sensitive than conventional EMG and is the most sensitive, but not specific, test for myasthenia gravis. Lambert-Eaton myasthenic syndrome, and other neuromusculasr junction pathology. It has been useful in the evaluation of some neuropathies and myopathies and has provided valuable information on the motor unit spatial arrangement, territory, microphysiology, and pathophysiology.
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Affiliation(s)
- Justina L Tanhehco
- Department of Physical Medicine and Rehabilitation, Northwestern University, 345 East Superior Street, Chicago, IL 60611, USA.
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Abstract
Electrodiagnosis has a key role in the evaluation of patients presenting with weakness. The electrodiagnostician should maintain a broad inclusive differential diagnosis and tailor the examination using a sound conceptual framework. A clear understanding of what is normal provides the proper foundation upon which to judge electrodiagnostic findings. Many peripheral neuromuscular conditions manifest themselves in characteristic ways on NEE and nerve conduction testing, making them identifiable to the skilled electrodiagnostic medicine consultant.
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Affiliation(s)
- Timothy R Dillingham
- Department of Physical Medicine and Rehabilitation, Froedtert Memorial Lutheran Hospital, 9200 W. Wisconsin Avenue, Milwaukee, WI 53226, USA.
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De Haes A, Proost JH, Kuks JBM, van den Tol DC, Wierda JMKH. Pharmacokinetic/pharmacodynamic modeling of rocuronium in myasthenic patients is improved by taking into account the number of unbound acetylcholine receptors. Anesth Analg 2002; 95:588-96, table of contents. [PMID: 12198043 DOI: 10.1097/00000539-200209000-00018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED Patients with myasthenia gravis are more sensitive than healthy patients to nondepolarizing neuromuscular blocking drugs. We performed a pharmacokinetic/pharmacodynamic modeling study of rocuronium in eight myasthenic patients and eight matched control patients. Patients were anesthetized with propofol and sufentanil and a mixture of nitrous oxide/oxygen. Mechanomyographical monitoring of the adductor pollicis was applied. Rocuronium was infused at a rate of 25 micro g. kg(-1). min(-1) in myasthenic patients and 116.7 micro g. kg(-1). min(-1) in control patients and was terminated at 70% neuromuscular block. Arterial blood samples were drawn during onset and offset of the block and for 4 h after the administration of rocuronium. Plasma concentrations were determined by high-performance liquid chromatography. Pharmacokinetic/pharmacodynamic modeling was performed by using the Sheiner model and the unbound receptor model (URM), which takes into account the number of unbound acetylcholine receptors. The effective concentration at 50% effect and the steepness of the concentration-effect relationship were significantly decreased in myasthenic patients. Both the URM and the Sheiner model provided an adequate fit in myasthenic patients. The acetylcholine receptor concentration was significantly decreased in myasthenic patients. The URM explains the observed differences in time course and potency, whereas the Sheiner model does not. IMPLICATIONS We performed a pharmacokinetic/pharmacodynamic modeling study in myasthenic patients and control patients. The unbound receptor model, which takes into account the number of unbound acetylcholine receptors in the biophase, was introduced and compared with the model proposed by Sheiner.
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Affiliation(s)
- Ann De Haes
- Research Group for Experimental Anesthesiology and Clinical Pharmacology, University Hospital Groningen, PO Box 30001, 9700 RB Groningen, The Netherlands.
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De Haes A, Proost JH, Kuks JBM, van den Tol DC, Wierda JMKH. Pharmacokinetic/Pharmacodynamic Modeling of Rocuronium in Myasthenic Patients Is Improved by Taking into Account the Number of Unbound Acetylcholine Receptors. Anesth Analg 2002. [DOI: 10.1213/00000539-200209000-00018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Jitter measurement with axonal microstimulation was used to study synaptic function at 115 neuromuscular junctions (NMJs) of normal subjects at various stimulation rates. Jitter was lowest at 0.5 Hz; it increased slightly at 1, 2, and 5 Hz and remained at that level at 10 Hz (a light work load) and 20 Hz (a heavy work load); and it increased further at 50 Hz (an extreme load). This pattern was seen for the majority of the NMJs, suggesting a high safety factor of neuromuscular transmission maintained rather uniformly over a wide range of discharge rates. A proportion of the normal NMJs had relatively large jitter; these tended to show prominent facilitation as the rate was raised from 5 or 10 to 20 Hz. Similar but more dramatic facilitation improving the safety factor was seen at most NMJs in myasthenia, which was studied for comparison. Such facilitation was not found at normal NMJs with low jitter.
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Affiliation(s)
- Joze V Trontelj
- Institute of Clinical Neurophysiology, University Medical Center, Zaloska 7, SI-1525 Ljubljana, Slovenia.
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Lo YL, Leoh TH, Tan YE, Foo ML, Dan YF, Ratnagopal P. Repetitive hypoglossal nerve stimulation in myasthenia gravis. Clin Neurophysiol 2002; 113:1227-30. [PMID: 12140000 DOI: 10.1016/s1388-2457(02)00120-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To assess the diagnostic efficacy of repetitive nerve stimulation (RNS) of the hypoglossal nerve in patients with myasthenia gravis (MG) and bulbar symptoms (dysphagia, dysarthria). METHODS Twenty patients with MG and 25 normal controls had RNS of the hypoglossal nerve. All patients also had single fibre electromyography (SFEMG) of the orbicularis oculi and RNS with recordings of the nasalis, trapezius and abductor pollicis brevis muscles. RESULTS All patients had positive SFEMG studies. Nine patients with bulbar symptoms had positive hypoglossal RNS, including 3 with negative RNS recordings in other muscles. Eleven patients with no bulbar symptoms showed negative hypoglossal RNS, including two with positive RNS recordings from other muscles. CONCLUSIONS Abnormal RNS of the hypoglossal nerve correlates well with bulbar dysfunction and further characterises the extent of neuromuscular transmission defect in MG patients.
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Affiliation(s)
- Y L Lo
- Department of Neurology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
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Abstract
BACKGROUND There are many agents in clinical use that manipulate central nervous system levels of epinephrine, dopamine, and serotonin. However, development of pharmacological options to manipulate central acetylcholine systems has lagged behind because of poor penetration of the blood-brain barrier and significant peripheral nervous system side effects. Newer agents have demonstrated some efficacy in the management of behavioral and cognitive side effects in Alzheimer's disease, and preliminary data in traumatic brain injury suggest acetylcholine esterase inhibitors may play a significant role in the treatment of this patient population as well. CONCLUSIONS In this article, the basic neuroanatomy and pharmacology of the central acetylcholine system are reviewed, along with agents currently available for clinical use.
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Affiliation(s)
- Philip J Blount
- Charlotte Institute of Rehabilitation, 1100 Blythe Boulevard, Charlotte, NC 28203, USA
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50
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Abstract
BACKGROUND In myasthenia gravis (MG), the prototypic autoimmune disease, antibodies against acetylcholine receptors impair neuromuscular transmission and produce weakness. Although recognized for several hundred years, it has only been over the last three decades that effective treatments have become available for MG. REVIEW SUMMARY This review summarizes the principles of normal neuromuscular transmission, the clinical features of MG, and the tests available for its diagnosis. The current treatments for MG are discussed, including possible mechanisms of action and a discussion of potential adverse effects. When available, evidence-based justification for individual treatment options is given, and areas of controversy identified. CONCLUSIONS Significant improvements in the diagnosis and management of MG have been made over the last several decades. The available treatments either improve neuromuscular transmission directly, or suppress or modulate the pathogenic immune response in MG. Treatment is highly individualized and must take into account the severity of disease, the presence of other diseases, and the kinetics of response for the available treatments. This requires detailed knowledge of the mechanisms of action and possible adverse effects for each treatment. However, despite an optimistic outlook with modern treatment, the management of MG continues to be plagued by lack of efficacy in some, and significant adverse effects in most MG patients.
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Affiliation(s)
- Michael W Nicolle
- Department of Clinical Neurological Sciences, London Health Sciences Center, The University of Western Ontario, London, Ontario, Canada.
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