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Periviita V, Jokela M, Palmio J, Udd B. A retrospective study of accuracy and usefulness of electrophysiological exercise tests. J Neurol 2024; 271:1802-1812. [PMID: 38055022 PMCID: PMC10972914 DOI: 10.1007/s00415-023-12110-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/26/2023] [Accepted: 11/09/2023] [Indexed: 12/07/2023]
Abstract
OBJECTIVES This study aimed to determine the usefulness of electrophysiological exercise tests. The significance of slightly abnormal exercise tests was also examined. METHODS We identified all the patients who had undergone exercise testing between February 2007 to June 2022 in Tampere University Hospital, Finland. Their medical records after diagnostic workup and exercise test reports were reviewed. A binary logistic regression was performed to evaluate the association between positive test result in short exercise test, long exercise test, or short exercise test with cooling and genetically confirmed skeletal muscle channelopathy or myotonic disorder. RESULTS We identified 256 patients. 27 patients were diagnosed with nondystrophic myotonia, periodic paralysis, myotonic dystrophy type 1, myotonic dystrophy type 2, or other specified myopathy. 14 patients were suspected to have a skeletal muscle channelopathy, but pathogenic variants could not be identified. The remaining 215 patients were diagnosed with other conditions than skeletal muscle channelopathy or myotonic disorder. The combined sensitivity of exercise tests was 59.3% and specificity 99.1%. Abnormal exercise test result was associated with increased risk of skeletal muscle channelopathy or myotonic disorder (OR 164.3, 95% CI 28.3-954.6, p < 0.001). CONCLUSIONS Electrophysiological exercise test is not optimal to exclude skeletal muscle channelopathy. It may be useful if a skeletal muscle channelopathy is suspected and genetic testing is negative or indeterminate and further evidence is required. Slightly abnormal exercise test results are possible in various conditions and result from different aetiologies. There is a demand for neurophysiological studies with higher sensitivity to detect skeletal muscle channelopathies.
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Affiliation(s)
- Vesa Periviita
- Department of Clinical Neurophysiology, Tampere University Hospital, Tampere, Finland.
| | - Manu Jokela
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
- Neurocenter, Turku University Hospital, Turku, Finland
- Neurology, Clinical Medicine, University of Turku, Turku, Finland
| | - Johanna Palmio
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
| | - Bjarne Udd
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
- Folkhälsan Research Center, Helsinki, Finland
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2
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [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: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Prolonged Exercise Test in Patients With History of Thyrotoxicosis. J Clin Neurophysiol 2022; 39:307-311. [PMID: 32773648 DOI: 10.1097/wnp.0000000000000766] [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
PURPOSE Thyrotoxic periodic paralysis is characterized by recurrent episodes of reversible, severe proximal muscle weakness associated with hypokalemia and hyperthyroidism. Prolonged exercise test is an easy, noninvasive method of demonstrating abnormal muscle membrane excitability in periodic paralyses. Although abnormal in thyrotoxic periodic paralysis patients, the effects thyroid hormone levels in non-thyrotoxic periodic paralysis thyrotoxicosis patients have not been well studied. The study aims to evaluate thyrotoxicosis patients (regardless of thyrotoxic periodic paralysis history) with prolonged exercise test and correlate it with their thyroid status. METHODS This is a prospective, cross-sectional study of consecutive thyrotoxicosis patients seen at the endocrine clinic of a tertiary medical center. Thyroid status was determined biochemically before prolonged exercise test. Compound muscle action potential (CMAP) amplitudes postexercise were compared against pre-exercise amplitudes and recorded as percentage of mean baseline CMAP amplitude. Comparisons of time-dependent postexercise CMAP amplitudes and mean CMAP amplitude decrement were made between hyperthyroid and nonhyperthyroid groups. RESULTS Seventy-four patients were recruited, 23 (31%) men, 30 (41%) Chinese, and the mean age was 48.5 ± 16.8 years. Of 74 patients, 32 (43%) were hyperthyroid and 42 (57%) were nonhyperthyroid viz. euthyroid and hypothyroid. Time-dependent CMAP amplitudes from 10 to 45 minutes after exercise were significantly lower in hyperthyroid patients compared with nonhyperthyroid patients (P < 0.01). Mean CMAP amplitude decrement postexercise was significantly greater in hyperthyroid than nonhyperthyroid patients (23.4% ± 11.4% vs. 17.3% ± 10.5%; P = 0.02). CONCLUSIONS Compound muscle action potential amplitude declines on prolonged exercise test were significantly greater in hyperthyroid patients compared with nonhyperthyroid patients. Muscle membrane excitability is highly influenced by thyroid hormone level. Thyrotoxic periodic paralysis occurs from increased levels of thyroid hormone activity in susceptible patients.
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Ribeiro A, Suetterlin KJ, Skorupinska I, Tan S, Morrow JM, Matthews E, Hanna MG, Fialho D. The long exercise test as a functional marker of periodic paralysis. Muscle Nerve 2022; 65:581-585. [PMID: 34817893 PMCID: PMC7614949 DOI: 10.1002/mus.27465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 11/07/2022]
Abstract
AIMS The aim of this study was to evaluate the sensitivity of the long exercise test (LET) in the diagnosis of periodic paralysis (PP) and assess correlations with clinical phenotypes and genotypes. METHODS From an unselected cohort of 335 patients who had an LET we analyzed 67 patients with genetic confirmation of PP and/or a positive LET. RESULTS 32/45 patients with genetically confirmed PP had a significant decrement after exercise (sensitivity of 71%). Performing the short exercise test before the LET in the same hand confounded results in four patients. Sensitivity was highest in patients with frequent (daily or weekly) attacks (8/8, 100%), intermediate with up to monthly attacks (15/21, 71%) and lowest in those with rare attacks (9/16, 56%) (p = .035, Mann-Whitney U-test). Patients with a positive LET without confirmed PP mutation comprised those with typical PP phenotype and a group with atypical features. DISCUSSION In our cohort, the LET is strongly correlated with the frequency of paralytic attacks suggesting a role as a functional marker. A negative test in the context of frequent attacks makes a diagnosis of PP unlikely but it does not rule out the condition in less severely affected patients.
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Affiliation(s)
- Ana Ribeiro
- Department of Clinical Neurophysiology, King’s College Hospital, London, UK
| | - Karen J Suetterlin
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
- Department of Clinical Neurophysiology, Royal Victoria Infirmary, Newcastle Upon Tyne, UK
| | - Iwona Skorupinska
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
| | - S.Veronica Tan
- Department of Neurology and Neurophysiology, St Thomas’ Hospital, Guy’s and St Thomas’ NHS Foundation Trust and Department of Academic Neurosciences, Kings College London, UK
| | - Jasper M Morrow
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
| | - Emma Matthews
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
- Atkinson-Morley Neuromuscular Centre, St George’s University Hospitals NHS Foundation Trust, London, UK
| | - Michael G Hanna
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
| | - Doreen Fialho
- Department of Clinical Neurophysiology, King’s College Hospital, London, UK
- Queen Square Centre for Neuromuscular Diseases, University College London, UK
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Logigian E. The long exercise test: new insights on an old technique. Muscle Nerve 2022; 65:495-497. [PMID: 35064932 DOI: 10.1002/mus.27503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/11/2022] [Accepted: 01/15/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Eric Logigian
- Department of Neurology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY
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Treatment and Management of Disorders of Neuromuscular Hyperexcitability and Periodic Paralysis. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00018-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Ji F, Ke Q, Wang K, Luo BY. Exercise test for patients with new-onset paroxysmal kinesigenic dyskinesia. Neurol Sci 2021; 42:4623-4628. [PMID: 33661484 DOI: 10.1007/s10072-021-05118-0] [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: 03/07/2020] [Accepted: 02/03/2021] [Indexed: 10/22/2022]
Abstract
The pathogenesis of primary paroxysmal kinesigenic dyskinesia (PKD) remains unclear, and channelopathy is a possibility. In a pilot study, we found that PKD patients had abnormal exercise test (ET) results. To investigate the ET performances in patients affected by PKD, and the role of the channelopathies in the pathogenesis of PKD, we compared the ET results of PKD patients, control subjects, and hypokalemic periodic paralysis (HoPP) patients, and we analyzed ET changes in 32 PKD patients before and after treatment. Forty-four PKD patients underwent genetic testing for the PRRT2, SCN4A, and CLCN1 genes. Sixteen of 59 (27%) patients had abnormal ET results in the PKD group, while 28 of 35 (80%) patients had abnormal ET results in the HoPP group. Compared with the control group, the PKD group showed a significant decrease in the compound muscle action potential (CMAP) amplitude and area after the long ET (LET), while the HoPP group showed not only greater decreases in the CMAP amplitude and area after the LET but also greater increases in the CMAP amplitude and area immediately after the LET. The ET parameters before and after treatment were not significantly different. Nine of 44 PKD patients carried PRRT2 mutations, but the gene abnormalities were unrelated to any ET parameter. The PKD group demonstrated an abnormal LET result by electromyography (EMG), and this abnormality did not seem to correlate with the PRRT2 variant or sodium channel blocker therapy.
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Affiliation(s)
- Fang Ji
- Department of Neurology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Qing Ke
- Department of Neurology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Kang Wang
- Department of Neurology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310000, China.
| | - Ben-Yan Luo
- Department of Neurology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310000, China.
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Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC, Fontaine B, Griggs RC, Hanna MG, Matthews E, Meola G, Sansone VA, Trivedi JR, van Engelen BG, Vicart S, Statland JM. Guidelines on clinical presentation and management of nondystrophic myotonias. Muscle Nerve 2020; 62:430-444. [PMID: 32270509 PMCID: PMC8117169 DOI: 10.1002/mus.26887] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.
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Affiliation(s)
- Bas C. Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Samantha LoRusso
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - W. David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Richard J. Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Robert C. Griggs
- Department of Neurology, University of Rochester, Rochester, New York
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valeria A. Sansone
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Neurorehabilitation Unit, University of Milan, NEuroMuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy
| | - Jaya R. Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Savine Vicart
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Jeffrey M. Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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Abstract
Andersen-Tawil syndrome (ATS) is a very rare orphan genetic multisystem channelopathy without structural heart disease (with rare exceptions). ATS type 1 is inherited in an autosomal dominant fashion and is caused by mutations in the KCNJ2 gene, which encodes the α subunit of the K+ channel protein Kir2.1 (in ≈ 50-60% of cases). ATS type 2 is in turn linked to a rare mutation in the KCNJ5-GIRK4 gene that encodes the G protein-sensitive-activated inwardly rectifying K+ channel Kir3.4 (15%), which carries the acetylcholine-induced potassium current. About 30% of cases are de novo/sporadic, suggesting that additional as-yet unidentified genes also cause the disorder. A triad of periodic muscle paralysis, repolarization changes in the electrocardiogram, and structural body changes characterize ATS. The typical muscular change is episodic flaccid muscle weakness. Prolongation of the QU/QUc intervals and normal or minimally prolonged QT/QTc intervals with a tendency to ventricular arrhythmias are typical repolarization changes. Bidirectional ventricular tachycardia is the hallmark ventricular arrhythmia, but also premature ventricular contractions, and rarely, polymorphic ventricular tachycardia of torsade de pointes type may be present. Patients with ATS have characteristic physical developmental dysmorphisms that affect the face, skull, limbs, thorax, and stature. Mild learning difficulties and a distinct neurocognitive phenotype (deficits in executive function and abstract reasoning) have been described. About 60% of affected individuals have all features of the major triad. The purpose of this review is to present historical aspects, nomenclature (observations/criticisms), epidemiology, genetics, electrocardiography, arrhythmias, electrophysiological mechanisms, diagnostic criteria/clues of periodic paralysis, prognosis, and management of ATS.
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10
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Zhang L, Niu J, Li Y, Guan Y, Cui L, Liu M. Abduction range: A potential parameter for the long exercise test in hypokalemic periodic paralysis during inter-attack periods. Muscle Nerve 2019; 61:104-107. [PMID: 31587332 DOI: 10.1002/mus.26721] [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: 01/08/2019] [Revised: 09/14/2019] [Accepted: 09/16/2019] [Indexed: 11/09/2022]
Abstract
BACKGROUND The abduction range of the little finger in the long exercise test (ET) has rarely been reported in patients with hypokalemic periodic paralysis (HypoPP) during inter-attack periods, and the diagnostic value requires clarification. METHODS The long ET was performed in 43 HypoPP patients during inter-attack periods and in 20 healthy controls (HCs). The compound muscle action potential (CMAP) and the abduction range of the little finger were recorded concurrently. RESULTS There were significant differences in the percent changes of the CMAP amplitudes and the abduction ranges after exercise between HypoPP patients and the HCs. The curve of percent changes in abduction ranges overlapped substantially with that of the CMAP amplitudes, and the sensitivity, specificity, and cutoff values were 0.860, 0.900, and 22.6%, respectively. CONCLUSIONS The abduction range of the little finger can serve as a novel parameter in the long ET for the diagnosis of HypoPP during inter-attack periods.
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Affiliation(s)
- Lei Zhang
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Jingwen Niu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Li
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Yuzhou Guan
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Liying Cui
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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von Wild T, Brunelli GA, von Wild KR, Löhnhardt M, Catoi C, Catoi AF, Vester JC, Strilciuc S, Trillenberg P. Regeneration of Denervated Skeletal Muscles - Brunelli's CNS-PNS Paradigm. J Med Life 2019; 12:342-353. [PMID: 32025252 PMCID: PMC6993288 DOI: 10.25122/jml-2019-0063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 11/20/2019] [Indexed: 12/02/2022] Open
Abstract
The restoration of voluntary muscle activity in posttraumatic paraplegia in both animal experiments and other clinical applications requires reproducibility of a technically-demanding microsurgical procedure, limited by physicians' understanding of Brunelli's spinal cord grafting paradigm. The insufficient clinical investigation of the long-term benefits of the CNS-PNS graft application warrants additional inquiry. The objective of this study is to explore the potential benefits of the first replicated, graft-induced neuroregeneration of denervated skeletal muscle regarding long-term clinical outcomes and to investigate the effect of Cerebrolysin on neuromodulation. A randomized study evaluating 30 rats, approved by the National Animal Ethics Advisory Committee was performed. The medication was administered postoperatively. For 14 days, 12 rats received Cerebrolysin (serum), 11 received NaCl 0.9% (shams), and 7 were controls. For microsurgery, the lateral corticospinal tract T10 was grafted to the denervated internal obliquus abdominal muscle. On day 90, intraoperative proof of reinnervation was observed. On day 100, 15 rats were euthanized for fixation, organ removal, and extensive histology-morphology examination, and the Wei-Lachin statistical procedure was employed. After an open revision of 16 rats, 8 were CMAP positive. After intravenous Vecuronium application, two (Cerebrolysin, NaCl) out of two rats showed an incomplete compound muscle action potential (CMAP) loss due to glutamatergic and cholinergic co-transmission, while two others showed a complete loss of amplitude. Cerebrolysin medication initiated larger restored muscle fiber diameters and less scarring. FB+ neurons were not observed in the brain but were observed in the Rexed laminae. Brunelli's concept was successfully replicated, demonstrating the first graft induced existence of cholinergic and glutamatergic neurotransmission in denervated grafted muscles. Statistics of the histometric count of muscle fibers revealed larger fiber diameters after Cerebrolysin. Brunelli's CNS-PNS experimental concept is suitable to analyze graft-neuroplasticity focused on the voluntary restoration of denervated skeletal muscles in spinal cord injury. Neuroprotection by Cerebrolysin is demonstrated.
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Affiliation(s)
- Tobias von Wild
- Department of Plastic Reconstructive and Aesthetic Surgery, Hand Surgery, Praxisklinik in der Alster City, Hamburg, Germany
| | - Giorgio A. Brunelli
- School of Specialists in Orthopedics, Traumatology, Hand and Microsurgery, University of Brescia, Brescia, Italy
- Foundation Giorgio Brunelli for Research on Spinal Cord Lesions ONLUS, E.S.C.R.I., Brescia, Italy
| | - Klaus R.H. von Wild
- Department of Neurosurgery, Medical Faculty Westphalia Wilhelm’s University Münster, Münster, Germany
- International Neuroscience Institute, Hanover, Germany
| | - Marlene Löhnhardt
- Department of Plastic and Reconstructive Surgery, Hand Surgery, University Hospital, Hamburg, Germany
| | - Cornel Catoi
- Department of Pathology, University of Agricultural Science and Veterinary Medicine, Cluj-Napoca, Romania
| | - Adriana Florinela Catoi
- Department of Functional Biosciences, University of Medicine and Pharmacy “Iuliu Hatieganu”, Cluj-Napoca, Romania
| | - Johannes C. Vester
- Department of Biometry & Clinical Research, idv Data Analysis and Study Planning, Gauting, Germany
| | - Stefan Strilciuc
- Department of Neurology, University of Medicine and Pharmacy “Iuliu Hatieganu”, Cluj-Napoca; Romania
| | - Peter Trillenberg
- Department of Neurology, University Medical Center Schleswig-Holstein, Lübeck, Germany
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Huang S, Zhang W, Chang X, Guo J. Overlap of periodic paralysis and paramyotonia congenita caused by SCN4A gene mutations two family reports and literature review. Channels (Austin) 2019; 13:110-119. [PMID: 30931713 PMCID: PMC6527082 DOI: 10.1080/19336950.2019.1600967] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Objective: To verify the diagnosis of channelopathies in two families and explore the mechanism of the overlap between periodic paralysis (PP) and paramyotonia congenita (PMC). Methods: We have studied two cases with overlapping symptoms of episodic weakness and stiffness in our clinical center using a series of assessment including detailed medical history, careful physical examination, laboratory analyses, muscle biopsy, electrophysiological evaluation, and genetic analysis. Results: The first proband and part of his family with the overlap of PMC and hyperkalemic periodic paralysis (HyperPP) has been identified as c.2111C > T (T704M) substitution of the gene SCN4A. The second proband and part of his family with the overlap of PMC and hypokalemic periodic paralysis type 2 (HypoPP2) has been identified as c.4343G > A (R1448H) substitution of the gene SCN4A. In addition, one member of the second family with overlapping symptoms has been identified as a novel mutation c.2111C > T without the mutation c.4343G > A. Conclusions: SCN4A gene mutations can cause the overlap of PMC and PP (especially the HypoPP2). The clinical symptoms of episodic weakness and stiffness could happen at a different time or temperature. Based on diagnosis assessments such as medical history and muscle biopsy, further evaluations on long-time exercise test, genetic analysis, and patch clamp electrophysiology test need to be done in order to verify the specific subtype of channelopathies. Furthermore, the improvement of one member in the pregnancy period can be used as a reference for the other female in the child-bearing period with T704M.
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Affiliation(s)
- Shan Huang
- a First Clinical Medical College , Shanxi Medical University , Taiyuan , China
| | - Wei Zhang
- b Department of Neurology, First Affiliated Hospital , Shanxi Medical University , Taiyuan , China
| | - Xueli Chang
- b Department of Neurology, First Affiliated Hospital , Shanxi Medical University , Taiyuan , China
| | - Junhong Guo
- b Department of Neurology, First Affiliated Hospital , Shanxi Medical University , Taiyuan , China
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13
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Shapiro BE, Preston DC. Looking for periodic paralysis: Optimizing the long exercise test. Muscle Nerve 2019; 59:8-9. [PMID: 30071152 DOI: 10.1002/mus.26314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 07/24/2018] [Accepted: 07/28/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Barbara E Shapiro
- Neurological Institute, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Cleveland, Ohio, 44106-5098, USA
| | - David C Preston
- Neurological Institute, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Cleveland, Ohio, 44106-5098, USA
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Simmons DB, Lanning J, Cleland JC, Puwanant A, Twydell PT, Griggs RC, Tawil R, Logigian EL. Long Exercise Test in Periodic Paralysis: A Bayesian Analysis. Muscle Nerve 2019; 59:47-54. [PMID: 29752813 DOI: 10.1002/mus.26157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 04/30/2018] [Accepted: 05/05/2018] [Indexed: 11/08/2022]
Abstract
INTRODUCTION The long exercise test (LET) is used to assess the diagnosis of periodic paralysis (PP), but LET methodology and normal "cutoff" values vary. METHODS To determine optimal LET methodology and cutoffs, we reviewed LET data (abductor digiti minimi motor response amplitude, area) from 55 patients with PP (32 genetically definite) and 125 controls. Receiver operating characteristic curves were constructed, and area under the curve (AUC) was calculated to compare (1) peak-to-nadir versus baseline-to-nadir methodologies and (2) amplitude versus area decrements. Using bayesian principles, we calculated optimal cutoff decrements that achieved 95% posttest probability of PP for various pretest probabilities (PreTPs). RESULTS AUC was highest for peak-to-nadir methodology and equal for amplitude and area decrements. For PreTP ≤ 50%, optimal decrement cutoffs (peak-to-nadir) were > 40% (amplitude) or > 50% (area). DISCUSSION For confirmation of PP, our data endorse the diagnostic utility of peak-to-nadir LET methodology using 40% amplitude or 50% area decrement cutoffs for PreTP ≤50%. Muscle Nerve 59:47-54, 2019.
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Affiliation(s)
- Daniel B Simmons
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, 14642, USA.,Department of Neurology, San Antonio Military Medical Center, Fort Sam Houston, Texas, USA
| | - Julie Lanning
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, 14642, USA
| | - James C Cleland
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | - Araya Puwanant
- Department of Neurology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | | | - Robert C Griggs
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, 14642, USA
| | - Rabi Tawil
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, 14642, USA
| | - Eric L Logigian
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, 14642, USA
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15
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Zhou HY, Zhan FX, Tian WT, Zhang C, Wang Y, Zhu ZY, Liu XL, Xu YQ, Luan XH, Huang XJ, Chen SD, Cao L. The study of exercise tests in paroxysmal kinesigenic dyskinesia. Clin Neurophysiol 2018; 129:2435-2441. [PMID: 30293034 DOI: 10.1016/j.clinph.2018.09.004] [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: 05/29/2018] [Revised: 08/14/2018] [Accepted: 09/01/2018] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To unravel if there was muscular ion channel dysfunction in paroxysmal kinesigenic dyskinesia (PKD) patients using the exercises tests (ET). METHODS Sixty PKD patients including 28 PRRT2 mutations carriers were enrolled in this study, as well as 19 hypokalaemic periodic paralysis (HypoPP) patients as the positive controls and 45 healthy subjects as the negative controls. ET including long exercise test (LET) and short exercise test (SET) was performed in the corresponding subjects. RESULTS In the LET, both the overall PKD patients and HypoPP patients had greater CMAP amplitude and area increments during exercise than healthy controls. At most 25% of PKD patients were identified from the normality with greater amplitude increment than the area. On the contrary, 50% of HypoPP patients were differentiated with greater area increment than the amplitude. More percentage of PRRT2- patients than PRRT2+ patients had abnormal average amplitude increment. Unexpectedly, five PKD patients had abnormal maximum CMAP amplitude decrements after exercise in the LET, and one had abnormal maximum immediate amplitude decrement in the SET. CONCLUSIONS Distinct ET manifestations were found in PKD patients compared to normal controls and HypoPP patients. SIGNIFICANCE Abnormal muscle membrane excitability might be involved in the mechanisms responsible for PKD.
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Affiliation(s)
- Hai-Yan Zhou
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fei-Xia Zhan
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wo-Tu Tian
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chao Zhang
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Wang
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ze-Yu Zhu
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Li Liu
- Department of Neurology, Shanghai Fengxian District Central Hospital, Shanghai Jiao Tong University Affiliated Sixth People's Hospital South Campus, Shanghai, China
| | - Yang-Qi Xu
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xing-Hua Luan
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Jun Huang
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sheng-Di Chen
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Li Cao
- Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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16
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Statland JM, Fontaine B, Hanna MG, Johnson NE, Kissel JT, Sansone VA, Shieh PB, Tawil RN, Trivedi J, Cannon SC, Griggs RC. Review of the Diagnosis and Treatment of Periodic Paralysis. Muscle Nerve 2017; 57:522-530. [PMID: 29125635 PMCID: PMC5867231 DOI: 10.1002/mus.26009] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/24/2017] [Accepted: 11/07/2017] [Indexed: 01/16/2023]
Abstract
Periodic paralyses (PPs) are rare neuromuscular disorders caused by mutations in skeletal muscle sodium, calcium, and potassium channel genes. PPs include hypokalemic paralysis, hyperkalemic paralysis, and Andersen‐Tawil syndrome. Common features of PP include autosomal dominant inheritance, onset typically in the first or second decades, episodic attacks of flaccid weakness, which are often triggered by diet or rest after exercise. Diagnosis is based on the characteristic clinic presentation then confirmed by genetic testing. In the absence of an identified genetic mutation, documented low or high potassium levels during attacks or a decrement on long exercise testing support diagnosis. The treatment approach should include both management of acute attacks and prevention of attacks. Treatments include behavioral interventions directed at avoidance of triggers, modification of potassium levels, diuretics, and carbonic anhydrase inhibitors. Muscle Nerve57: 522–530, 2018
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas, 66160, USA
| | - Bertrand Fontaine
- Sorbonne-Université, INSERM, AP-HP, Reference Center for Channelopathies, Department of Neuology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Michael G Hanna
- MRC Center for Neuromuscular Diseases, University College of London Institute of Neurology, London, England
| | - Nicholas E Johnson
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - John T Kissel
- Department of Neurology, The Ohio State University, Columbus, Ohio, USA
| | - Valeria A Sansone
- The NEMO Center, Neurorehabilitation Unit, University of Milan, Italy
| | - Perry B Shieh
- Department of Neurology, University of California at Los Angeles School of Medicine, Los Angeles, California, USA
| | - Rabi N Tawil
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Jaya Trivedi
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Stephen C Cannon
- Department of Physiology, University of California at Los Angeles School of Medicine, Los Angeles, California, USA
| | - Robert C Griggs
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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17
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Totomoch-Serra A, Márquez MF, Cervantes-Barragan DE. Clinical heterogeneity in Andersen-Tawil syndrome. Neuromuscul Disord 2017; 27:1074-1075. [DOI: 10.1016/j.nmd.2017.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 09/08/2017] [Indexed: 11/26/2022]
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18
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Tahmasbi Sohi M, Sullivan WJ, Anderson DJM. Transient Hypokalemic Quadriplegia After a Lumbar Transforaminal Epidural Dexamethasone Injection: A Case Report. PM R 2017; 10:544-547. [PMID: 29074369 DOI: 10.1016/j.pmrj.2017.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/11/2017] [Accepted: 10/15/2017] [Indexed: 11/26/2022]
Abstract
A 30-year-old man with no significant medical history presented with hypokalemic quadriplegia 4 hours after he received a lumbar transforaminal epidural steroid injection (ESI) containing dexamethasone and lidocaine. A comprehensive workup ruled out acquired and hereditary causes of hypokalemic paralysis. Symptoms gradually resolved within hours after potassium restoration with no residual neurologic deficits. Paralysis after transforaminal ESI is uncommon but has been associated with particulate steroids that can coalesce into aggregates and occlude vessels. To our knowledge, there have been no case reports of paralysis after ESI with dexamethasone, a nonparticulate steroid. This transient paralysis is possibly caused by the effects of glucocorticoids on Na-K channels and insulin resistance resulting in hyperglycemia and subsequent hypokalemia. We reviewed the differential diagnosis of transient paralysis after epidural steroid injection in this report. LEVEL OF EVIDENCE IV.
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Affiliation(s)
- Maryam Tahmasbi Sohi
- Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, 1055 Clermont Street (117), Denver, CO 80220; Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO.,Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora; and Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, Denver, CO.,Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO
| | - William J Sullivan
- Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, 1055 Clermont Street (117), Denver, CO 80220; Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO.,Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora; and Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, Denver, CO.,Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO
| | - Dustin J M Anderson
- Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, 1055 Clermont Street (117), Denver, CO 80220; Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO.,Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora; and Physical Medicine & Rehabilitation Service, VA Eastern Colorado Health Care System, Denver, CO.,Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Aurora, CO
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19
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Boudiba A, Aboubaker Zeid B. P251 Contribution of electrophysiology in muscular channelopathies diagnosis. Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2017.07.259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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Long Exercise Test in the Interattack Period of Periodic Paralysis: A Useful and Sensitive Diagnostic Tool. J Clin Neurophysiol 2017; 34:497-501. [PMID: 28742635 DOI: 10.1097/wnp.0000000000000405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE The reference values of long exercise test are inconsistent in previous studies. Our research aims to determine the reference values and improve diagnostic efficiency of long exercise test in periodic paralysis. METHODS In this study, 100 healthy controls, 35 non-periodic paralysis patients, and 47 patients with periodic paralysis were recruited. The procedures of long exercise test were conducted following McMannis(1986) method. RESULTS The decrease rate in compound muscle action potential amplitudes was correlated with gender, and it was not influenced by age, height, weight, and exercise. After analyzing receiver operating characteristic curves, the compound muscle action potential amplitude decrease rate was stratified by sex. The mean area under the curve, sensitivity, and specificity were higher in male and female than all pooled subjects. The reference values of compound muscle action potential amplitude decrease rate were 46.8% in male and 26.9% in female, respectively. CONCLUSIONS The long exercise test is a useful and sensitive diagnostic tool for primary periodic paralysis and thyrotoxic periodic paralysis. However, the reference values should be set by sex, which has better diagnostic performance, sensitivity, and specificity.
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21
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Son YR, Kim NH, Kim DG, Park KS. Is thyrotoxic periodic paralysis a disease caused by muscle membrane dysfunction? Muscle Nerve 2016; 56:780-786. [PMID: 28006864 DOI: 10.1002/mus.25532] [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: 01/13/2016] [Revised: 12/12/2016] [Accepted: 12/16/2016] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Thyrotoxic periodic paralysis (TPP) is characterized by recurrent episodes of reversible paralysis with hyperthyroidism. It is clinically similar to hypokalemic periodic paralysis (HOPP), which features significant ion-channel dysfunction and reduced muscle fiber conduction velocity (MFCV). However, the muscle membrane function in TPP is not known. METHODS For 13 patients with TPP and 15 age-matched controls, clinical assessment and serial neurophysiological testing, including nerve conduction, prolonged exercise (PE) testing, and MFCV. were performed. RESULTS MFCV values were elevated up to 1 year from the paralytic attack in TPP patients. In the group with a positive PE test, MFCV values were higher. There was no significant relationship between MFCV values and either hypokalemia or hyperthyroidism. CONCLUSIONS Although clinical manifestations in TPP are similar to those observed in HOPP, TPP appears to feature an alternate pathogenic mechanism. Specifically, MFCV values increased rather than decreased. Further studies are needed to support these findings. Muscle Nerve, 2016 Muscle Nerve 56: 780-786, 2017.
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Affiliation(s)
- Yoo-Ri Son
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea
| | - Nam-Hee Kim
- Department of Neurology, Dongguk University Ilsan Hospital, Goyangsi, Gyeonggido, Republic of Korea
| | - Dong-Gun Kim
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea
| | - Kyung-Seok Park
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea
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22
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Fan R, Ji R, Zou W, Wang G, Wang H, Penney DJ, Luo JJ, Fan Y. Concomitant presentation of Anderson-Tawil syndrome and myasthenia gravis in an adult patient: A case report. Exp Ther Med 2016; 12:2435-2438. [PMID: 27698745 PMCID: PMC5038206 DOI: 10.3892/etm.2016.3673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 04/29/2016] [Indexed: 11/05/2022] Open
Abstract
Andersen-Tawil syndrome (ATS) is an autosomal dominant, multisystem channelopathy characterized by periodic paralysis, ventricular arrhythmias and distinctive dysmorphic facial or skeletal features. The disorder displays marked intrafamilial variability and incomplete penetrance. Myasthenia gravis (MG) is an autoimmune disorder that demonstrates progressive fatigability, in which the nicotinic acetylcholine receptor (AChR) at neuromuscular junctions is the primary autoantigen. The present study reports a rare case of a 31-year-old woman with a history of morbid obesity and periodic weakness, who presented with hemodynamic instability, cardiogenic shock and facial anomalies. Laboratory results revealed hypokalemia and an elevated anti-AChR antibody expression levels. Electrocardiography demonstrated prolonged QT-interval, ST-elevation, and subsequent third-degree atrioventricular block. Neurological examination revealed bilateral ptosis, horizontal diplopia, dysarthria and generalized weakness. No mutations in the potassium channel inwardly rectifying subfamily J member 2 gene were detected in the present case. The patient was treated with oral potassium supplementation and an acetylcholinesterase inhibitor (pyridostigmine), after which the symptoms were improved. To the best of our knowledge, the present case report was the first to describe concomitant presentation of both ATS and MG, which represents a diagnostic and therapeutic challenge.
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23
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Zheng J, Liang Z, Hou Y, Liu F, Hu Y, Lin P, Yan C. A novel Kir2.6 mutation associated with hypokalemic periodic paralysis. Clin Neurophysiol 2016; 127:2503-8. [PMID: 27178871 DOI: 10.1016/j.clinph.2016.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 02/21/2016] [Accepted: 03/06/2016] [Indexed: 12/26/2022]
Abstract
BACKGROUND AND OBJECTIVE Mutations in KCNJ18, which encodes the inwardly rectifying potassium channel Kir2.6, have rarely been reported in hypokalemic periodic paralysis. We describe the clinical phenotype of a novel KCNJ18 gene mutation and perform functional characterization of this mutant Kir2.6. METHODS A long-term exercise test (ET) was conducted based on the McManis method. Whole-cell currents were recorded using patch clamp, and the HEK293 cells were transfected with wild-type or/and mutant Kir2.6 cDNA. RESULTS A de novo conserved heterozygous mutation in Kir2.6, G169R, was found in a hypokalemic periodic paralysis patient. ET led to a decrease in the amplitude of compound muscle action potential (CMAP) by 64%. Patch clamp results showed that the potassium inward and outward current densities of the G169R mutant were, respectively, reduced by 65.6% and 84.7%; for co-expression with wild type, which more closely resembles the physiological conditions in vitro, the inward and outward current densities decreased, respectively, by 48.2% and 47.4%. CONCLUSIONS A novel KCNJ18 mutation, G169R, was first reported to be associated with hypokalemic periodic paralysis without hyperthyroidism. Electrophysiological results demonstrated a significant functional defect of this mutant, which may predispose patients with this mutation to paralysis. SIGNIFICANCE This new G169R mutation of the potassium channel Kir2.6 provides insight into the pathogenic mechanisms of hypokalemic periodic paralysis.
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Affiliation(s)
- Jinfan Zheng
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Zonglai Liang
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Ying Hou
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Fuchen Liu
- Department of Neurobiology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Yuanyuan Hu
- Key Laboratory for Experimental Teratology of the Ministry of Education, Brain Science Research Institute, Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Pengfei Lin
- Key Laboratory for Experimental Teratology of the Ministry of Education, Brain Science Research Institute, Department of Neurology, Qilu Hospital, Shandong University, Jinan, China.
| | - Chuanzhu Yan
- Key Laboratory for Experimental Teratology of the Ministry of Education, Brain Science Research Institute, Department of Neurology, Qilu Hospital, Shandong University, Jinan, China.
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24
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Song IW, Sung CC, Chen CH, Cheng CJ, Yang SS, Chou YC, Yang JH, Chen YT, Wu JY, Lin SH. Novel susceptibility gene for nonfamilial hypokalemic periodic paralysis. Neurology 2016; 86:1190-8. [PMID: 26935888 DOI: 10.1212/wnl.0000000000002524] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/10/2015] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE To identify susceptibility genes to nonfamilial hypokalemic periodic paralysis (hypoKPP) consisting of thyrotoxic periodic paralysis (TPP) and sporadic periodic paralysis (SPP) and explore the potential pathogenic mechanisms. METHODS We enrolled patients with nonfamilial hypoKPP not carrying mutations in CACNA1S, SCN4A, KCNJ18, or KCNJ2 and conducted genome-wide association analyses comparing 77 patients with TPP and 32 patients with SPP with 1,730 controls in a Han Chinese population in Taiwan. Replication was performed using an independent Han Chinese cohort of 50 patients with TPP, 22 patients with SPP, and 376 controls. RESULTS We identified 4 single nucleotide polymorphisms (rs312692, rs312736, rs992072, rs393743) located about 100 Kb downstream of KCNJ2 on chromosome 17q24.3 associated with both TPP and SPP reaching genome-wide significance (p < 9 × 10(-8)). rs312736 was mapped to CTD-2378E21.1, a lincRNA, and direct sequencing revealed an exon variant rs312732 (risk allele A) highly associated with both TPP (p = 1.81 × 10(-12); odds ratio [OR] 3.22 [95% confidence interval (CI) 2.36-4.40]) and SPP (p = 8.6 × 10(-12); OR 5.4 [95% CI 3.17-9.18]). Overexpression of C (normal allele) CTD-2378E21.1 in C2C12 skeletal muscle cell, but not A (risk allele) CTD-2378E21.1, showed significantly decreased Kcnj2 expression, indicating A-type CTD-2378E21.1 has lost the ability to regulate Kcnj2. CONCLUSIONS Our study reveals a shared genetic predisposition between TPP and SPP. CTD-2378E21.1 is a novel disease-associated gene for both TPP and SPP and may negatively regulate KCNJ2 expression. These findings provide new insights into the pathogenesis of nonfamilial hypoKPP.
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Affiliation(s)
- I-Wen Song
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Chih-Chien Sung
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Chien-Hsiun Chen
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Chih-Jen Cheng
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Sung-Sen Yang
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Yi-Chun Chou
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Jenn-Hwai Yang
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Yuan-Tsong Chen
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan
| | - Jer-Yuarn Wu
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan.
| | - Shih-Hua Lin
- From the Institute of Biomedical Sciences (I.-W.S., C.-H.C., Y.-C.C., J.-H.Y., Y.-T.C., J.-Y.W.), Academia Sinica; Graduate Institute of Life Science (I.-W.S.), Division of Nephrology, Department of Medicine, Tri-Service General Hospital (C.-C.S., C.-J.C., S.-S.Y., S.-H.L.), and Graduate Institute of Medical Science (C.-C.S., S.-S.Y., S.-H.L.), National Defense Medical Center, Taipei, Taiwan; Department of Pediatrics (Y.-T.C.), Duke University Medical Center, Durham, NC; and Graduate Institute of Chinese Medical Science (J.-Y.W.), China Medical University, Taichung, Taiwan.
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Chakraborty P, Kaul B, Mandal K, Isser HS, Bansal S, Subramanian A. Bidirectional ventricular tachycardia of unusual etiology. Indian Pacing Electrophysiol J 2016; 15:296-9. [PMID: 27479206 PMCID: PMC4867968 DOI: 10.1016/j.ipej.2016.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Bidirectional ventricular tachycardia (BDVT) is a rare form of ventricular arrhythmia, characterized by changing QRS axis of 180 degrees. Digitalis toxicity is considered as commonest cause of BDVT; other causes include aconite toxicity, myocarditis, myocardial infarction, metastatic cardiac tumour and cardiac channelopathies. We describe a case of BDVT in a patient with Anderson-Tawil syndrome.
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Affiliation(s)
- Praloy Chakraborty
- Department of Cardiology, Vardhaman Mahavir Medical College and Safdarjang Hospital, Delhi, India
| | - Bhavna Kaul
- Department of Neurology, Vardhaman Mahavir Medical College and Safdarjang Hospital, Delhi, India
| | - Kausik Mandal
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - H S Isser
- Department of Cardiology, Vardhaman Mahavir Medical College and Safdarjang Hospital, Delhi, India
| | - Sandeep Bansal
- Department of Cardiology, Vardhaman Mahavir Medical College and Safdarjang Hospital, Delhi, India
| | - Anandaraja Subramanian
- Department of Cardiology, Indira Gandhi Government General Hospital and Postgraduate Institute, Pondicherry, India
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Reference value of long-time exercise test in the diagnosis of primary periodic paralysis. Chin Med J (Engl) 2014. [DOI: 10.1097/00029330-201409200-00005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Rodriguez-Falces J, Maffiuletti NA, Place N. Twitch and M-wave potentiation induced by intermittent maximal voluntary quadriceps contractions: differences between direct quadriceps and femoral nerve stimulation. Muscle Nerve 2013; 48:920-9. [PMID: 23536413 DOI: 10.1002/mus.23856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2013] [Indexed: 11/12/2022]
Abstract
INTRODUCTION The aim of this study was to investigate differences in twitch and M-wave potentiation in the quadriceps femoris when electrical stimulation is applied over the quadriceps muscle belly versus the femoral nerve trunk. METHODS M-waves and mechanical twitches were evoked using direct quadriceps muscle and femoral nerve stimulation between 48 successive isometric maximal voluntary contractions (MVC) from 10 young, healthy subjects. Potentiation was investigated by analyzing the changes in M-wave amplitude recorded from the vastus medialis (VM) and vastus lateralis (VL) muscles and in quadriceps peak twitch force. RESULTS Potentiation of twitch, VM M-wave, and VL M-wave were greater for femoral nerve than for direct quadriceps stimulation (P < 0.05). Despite a 50% decrease in MVC force, the amplitude of the M-waves increased significantly during exercise. CONCLUSIONS In addition to enhanced electrogenic Na(+) -K(+) pumping, other factors (such as synchronization in activation of muscle fibers and muscle architectural properties) may significantly influence the magnitude of M-wave enlargement.
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Affiliation(s)
- Javier Rodriguez-Falces
- Department of Electrical and Electronic Engineering, Universidad Pública de Navarra DIEE, Campus de Arrosadía s/n, 31006, Pamplona, Spain
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Abstract
INTRODUCTION Skeletal muscle channelopathies are rare disorders of muscle membrane excitability. Their episodic nature may result in diagnostic difficulty and delays in diagnosis. Advances in diagnostic clinical electrophysiology combined with DNA-based diagnosis have improved diagnostic accuracy and efficiency. Ascribing pathogenic status to identified genetic variants in muscle channel genes may be complex and functional analysis, including molecular expression, may help with this. Accurate clinical and genetic diagnosis enables genetic counselling, advice regarding prognosis and aids treatment selection. AREAS COVERED An approach to accurate and efficient diagnosis is outlined. The importance of detailed clinical evaluation including careful history, examination and family history is emphasised. The role of specialised electrodiagnostics combined with DNA testing and molecular expression is considered. New potential biomarkers including muscle MRI using MRC Centre protocols are discussed. EXPERT OPINION A combined diagnostic approach using careful clinical assessment, specialised neurophysiology and DNA testing will now achieve a clear diagnosis in most patients with muscle channelopathies. An accurate diagnosis enables genetic counselling and provides information regarding prognosis and treatment selection. Genetic analysis often identifies new variants of uncertain significance. In this situation, functional expression studies as part of a diagnostic service will enable determination of pathogenic status of novel genetic variants.
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Affiliation(s)
- Jennifer Spillane
- UCL, Institute of Neurology, MRC Centre for Neuromuscular Diseases , Queen Square, London, WC1N3BG UK ,
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Heatwole CR, Statland JM, Logigian EL. The diagnosis and treatment of myotonic disorders. Muscle Nerve 2013; 47:632-48. [PMID: 23536309 DOI: 10.1002/mus.23683] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2012] [Indexed: 12/12/2022]
Abstract
Myotonia is a defining clinical symptom and sign common to a relatively small group of muscle diseases, including the myotonic dystrophies and the nondystrophic myotonic disorders. Myotonia can be observed on clinical examination, as can its electrical correlate, myotonic discharges, on electrodiagnostic testing. Research interest in the myotonic disorders continues to expand rapidly, which justifies a review of the scientific bases, clinical manifestations, and numerous therapeutic approaches associated with these disorders. We review the pathomechanisms of myotonia, the clinical features of the dystrophic and nondystrophic myotonic disorders, and the diagnostic approach and treatment options for patients with symptomatic myotonia.
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Affiliation(s)
- Chad R Heatwole
- Department of Neurology, Box 673, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, New York 14642, USA.
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Abstract
Clinical and electrical myotonia is caused by a small group of neuromuscular disorders. This article reviews myotonia and its differential diagnosis. The use of electrodiagnostic testing to evaluate the primary myotonic disorders (myotonic dystrophy and the nondystrophic myotonias) is also discussed.
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Affiliation(s)
- Michael K Hehir
- Department of Neurology, University of Vermont, Burlington, VT 05401, USA.
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BoËRio D, Z'graggen WJ, Tan SV, Guetg A, Ackermann K, Bostock H. Muscle velocity recovery cycles: Effects of repetitive stimulation on two muscles. Muscle Nerve 2012; 46:102-11. [DOI: 10.1002/mus.23267] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Fortune E, Lowery MM. Effect of membrane properties on skeletal muscle fiber excitability: a sensitivity analysis. Med Biol Eng Comput 2012; 50:617-29. [PMID: 22430618 DOI: 10.1007/s11517-012-0894-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 03/10/2012] [Indexed: 11/25/2022]
Abstract
In this study, the sensitivity of skeletal muscle fiber excitability to changes in temperature and a range of geometrical, electrical and ionic membrane properties was examined using model simulation. A mathematical model of the propagating muscle fiber action potential (AP) was used to simulate muscle fiber APs while changing individual muscle fiber parameters in isolation to examine how they affect muscle fiber AP amplitude, shape and conduction velocity (CV). The behavior of the model was verified by comparison with previously reported experimental data from both in vivo studies conducted at physiological temperatures and in vitro and in silico studies conducted at lower temperatures. The simulation results presented demonstrate the sensitivity of AP amplitude, shape and CV and, therefore, muscle fiber excitability to small changes in a wide range of different muscle fiber parameters. Furthermore, they demonstrate the potential of computational modeling as a tool for investigating the underlying mechanisms of complex phenomena such as those which govern skeletal muscle excitation.
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Affiliation(s)
- Emma Fortune
- School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
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Tan SV, Matthews E, Barber M, Burge JA, Rajakulendran S, Fialho D, Sud R, Haworth A, Koltzenburg M, Hanna MG. Refined exercise testing can aid DNA-based diagnosis in muscle channelopathies. Ann Neurol 2011; 69:328-40. [PMID: 21387378 DOI: 10.1002/ana.22238] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To improve the accuracy of genotype prediction and guide genetic testing in patients with muscle channelopathies we applied and refined specialized electrophysiological exercise test parameters. METHODS We studied 56 genetically confirmed patients and 65 controls using needle electromyography, the long exercise test, and short exercise tests at room temperature, after cooling, and rewarming. RESULTS Concordant amplitude-and-area decrements were more reliable than amplitude-only measurements when interpreting patterns of change during the short exercise tests. Concordant amplitude-and-area pattern I and pattern II decrements of >20% were 100% specific for paramyotonia congenita and myotonia congenita, respectively. When decrements at room temperature and after cooling were <20%, a repeat short exercise test after rewarming was useful in patients with myotonia congenita. Area measurements and rewarming distinguished true temperature sensitivity from amplitude reduction due to cold-induced slowing of muscle fiber conduction. In patients with negative short exercise tests, symptomatic eye closure myotonia predicted sodium channel myotonia over myotonia congenita. Distinctive "tornado-shaped" neuromyotonia-like discharges may be seen in patients with paramyotonia congenita. In the long exercise test, area decrements from pre-exercise baseline were more sensitive than amplitude decrements-from-maximum-compound muscle action potential (CMAP) in patients with Andersen-Tawil syndrome. Possible ethnic differences in the normative data of the long exercise test argue for the use of appropriate ethnically-matched controls. INTERPRETATION Concordant CMAP amplitude-and-area decrements of >20% allow more reliable interpretation of the short exercise tests and aid accurate DNA-based diagnosis. In patients with negative exercise tests, specific clinical features are helpful in differentiating sodium from chloride channel myotonia. A modified algorithm is suggested.
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Affiliation(s)
- S Veronica Tan
- Medical Research Council Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, University College London, Institute of Neurology London, UK.
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Faguer S, Chauveau D, Cintas P, Tack I, Cointault O, Rostaing L, Vargas-Poussou R, Ribes D. Renal, ocular, and neuromuscular involvements in patients with CLDN19 mutations. Clin J Am Soc Nephrol 2010; 6:355-60. [PMID: 21030577 DOI: 10.2215/cjn.02870310] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND OBJECTIVES The objective of this study was to describe the renal and extrarenal findings in patients with recessively inherited familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) associated with CLDN19 mutations. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Medical records of three patients from two French unrelated families with CLDN19 mutations were retrospectively examined. RESULTS Direct sequencing of CLDN19 identified a known variant (p.Gly20Asp) in all patients and a new missense mutation (p.Val44Met) in one (compound heterozygous). The patients' renal phenotype closely mimicked CLDN16-related nephropathy: low serum Mg2+ (<0.65 mmol/L) despite oral supplementation, hypercalciuria partly thiazide-sensitive, and progressive renal decline with ESRD reached at age 16 and 22 years in two individuals. Primary characteristics (failure to thrive, recurrent urinary tract infections, or abdominal pain), age at onset (0.8 to 16 years), and rate of renal decline were highly heterogeneous. Ocular involvement was identified in all patients, although two patients did not have visual loss. Additionally, exercise intolerance with pain, weakness, and electromyographical alterations mimicking a Ca2+/K+ channelopathy (pattern V) were observed in two of three individuals. These features persisted despite the normalization of serum K+ and Mg2+ after renal transplantation. CONCLUSIONS Ocular manifestations, even subtle, and exercise intolerance mimicking mild to moderate periodic paralysis are two symptoms that need to be searched for in patients with FHHNC and may indicate CLDN19 mutations.
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Affiliation(s)
- Stanislas Faguer
- Service de Néphrologie et Immunologie Clinique, Centre de Référence des Maladies Rénales Rares, CHU Toulouse, Toulouse Cedex 9, France.
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Kumar KR, Ng K, Vandebona H, Davis MR, Sue CM. A novel CLCN1 mutation (G1652A) causing a mild phenotype of thomsen disease. Muscle Nerve 2010; 41:412-5. [PMID: 20120005 DOI: 10.1002/mus.21610] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We investigated a 62-year-old man who had mild clinical features of myotonia congenita. He was found to have a novel heterozygous G-to-A nucleotide substitution at position 1652 in exon 15 of the CLCN1 gene. Clinicogenetic studies performed on his family revealed that his asymptomatic son also shared the mutation. We conclude that a novel chloride channel mutation (G1652A) has caused a mild form of autosomal-dominant myotonia congenita (Thomsen disease) in this family.
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Affiliation(s)
- Kishore R Kumar
- Department of Neurology, Royal North Shore Hospital and University of Sydney, St. Leonards, New South Wales 2065, Australia
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Exercise test on the patients with normokalaemic periodic paralysis from a Chinese family with a mutation in the SCN4A gene. Chin Med J (Engl) 2008. [DOI: 10.1097/00029330-200810010-00012] [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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Thomas J, Tarleton J, Baker SK. Recessive CLCN1
mutation presenting as thomsen disease. Muscle Nerve 2008; 38:1515-1517. [DOI: 10.1002/mus.21121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Michel P, Sternberg D, Jeannet PY, Dunand M, Thonney F, Kress W, Fontaine B, Fournier E, Kuntzer T. Comparative efficacy of repetitive nerve stimulation, exercise, and cold in differentiating myotonic disorders. Muscle Nerve 2008; 36:643-50. [PMID: 17654559 DOI: 10.1002/mus.20856] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The decremental response of the compound muscle action potential (CMAP) to provocative tests is not characterized in genetically verified myotonic disorders. We therefore studied the relationship between decremental responses and mutation type in 10 patients with recessive myotonia congenita (rMC), two with paramyotonia congenita (PMC), nine with myotonic dystrophy type 1 (DM1), four with DM2, and 14 healthy people. CMAPs were measured at rest, just after a short exercise test (SET), and during short, 5- and 10-HZ, repetitive nerve stimulation (RNS) trains at 32 degrees C and at 20 degrees C. The degree of decrement was not related to the severity of clinical myotonia. Controls and PMC patients had similar responses when warm, but with cooling PMC patients had a persistent decrement of CMAPs. In the rMC patients the decremental responses were related to the type of mutation of the CLCN1 gene, as a decrement was encountered in the T268M, R894X, IVS17+1 G>T, K248X, and 2149 del G, but not with the IVS1+3 A>T, F167L, or dominant A313T mutations. In DM1 patients there was no relationship between decrement and CTG repeats. The degree of partial inexcitability in myotonic muscle membrane therefore depends on the mutation type rather than degree of clinical myotonia. RNS at 10 HZ is more sensitive than SET for demonstrating abnormalities in rMC patients when warm; differences are less marked when cold, which is useful to diagnose PMC. Provocative tests are therefore useful in myotonias to demonstrate muscle inexcitability, which depends on the chloride or sodium channelopathy.
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Affiliation(s)
- Patrik Michel
- Nerve-Muscle Unit, Neurology Service, CHU Vaudois and University of Lausanne, Room BH7/469, 1011 Lausanne, Switzerland
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Abstract
Periodic paralyses are rare diseases characterized by severe episodes of muscle weakness concomitant to variations in blood potassium levels. It is thus usual to differentiate hypokalemic, normokalemic, and hyperkalemic periodic paralysis. Except for thyrotoxic hypokalemic periodic paralysis and periodic paralyses secondary to permanent changes of blood potassium levels, all of these diseases are of genetic origin, transmitted with an autosomal-dominant mode of inheritance. Periodic paralyses are channelopathies, that is, diseases caused by mutations in genes encoding ion channels. The culprit genes encode for potassium, calcium, and sodium channels. Mutations of the potassium and calcium channel genes cause periodic paralysis of the same type (Andersen-Tawil syndrome or hypokalemic periodic paralysis). In contrast, distinct mutations in the muscle sodium channel gene are responsible for all different types of periodic paralyses (hyper-, normo-, and hypokalemic). The physiological consequences of the mutations have been studied by patch-clamp techniques and electromyography (EMG). Globally speaking, ion channel mutations modify the cycle of muscle membrane excitability which results in a loss of function (paralysis). Clinical physiological studies using EMG have shown a good correlation between symptoms and EMG parameters, enabling the description of patterns that greatly enhance molecular diagnosis accuracy. The understanding of the genetics and pathophysiology of periodic paralysis has contributed to refine and rationalize therapeutic intervention and will be without doubts the basis of further advances.
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Affiliation(s)
- Bertrand Fontaine
- INSERM, UMR 546, Paris, France; Université Pierre et Marie Curie-Paris 6, UMR S546 and Assistance Publique-Hôpitaux de Paris, Centre de référence des canalopathies musculaires, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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Arimura K, Arimura Y, Ng AR, Sakoda SI, Higuchi I. Muscle membrane excitability after exercise in thyrotoxic periodic paralysis and thyrotoxicosis without periodic paralysis. Muscle Nerve 2007; 36:784-8. [PMID: 17722048 DOI: 10.1002/mus.20865] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We evaluated whether the paralytic attacks in thyrotoxic periodic paralysis (TPP) are primarily due to the abnormal excitability of the muscle membrane caused by a preexisting latent abnormality or to the effects of thyroid hormone. The prolonged exercise (PE) test was used to evaluate muscle membrane excitability in 21 patients with TPP and 11 patients with thyrotoxicosis without paralytic attacks (Tw/oPP) in the hyperthyroid state. The PE tests were compared between the hyperthyroid and euthyroid states in five of the TPP and three of the Tw/oPP patients. Compared to 20 healthy subjects, a significant increase in compound muscle action potential (CMAP) amplitudes immediately after exercise and a significant time-dependent gradual decline in CMAP amplitudes starting from 20 min after exercise were observed in the TPP patients. A significant decline in CMAP amplitudes was also observed in the Tw/oPP patients but only at 50 min after exercise. All of the TPP and Tw/oPP patients had a tendency to improve in the euthyroid state; the PE tests remained abnormal only in the TPP patients. Paralytic attacks in TPP patients are due primarily to a preexisting latent abnormal excitability of the muscle membrane, possibly genetic in origin.
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Affiliation(s)
- Kimiyoshi Arimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan.
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Cleland JC, Logigian EL. Clinical evaluation of membrane excitability in muscle channel disorders: potential applications in clinical trials. Neurotherapeutics 2007; 4:205-15. [PMID: 17395130 DOI: 10.1016/j.nurt.2007.01.011] [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] [Indexed: 10/23/2022] Open
Abstract
Muscle channelopathies are inherited disorders that cause paralysis and myotonia. Molecular technology has contributed immeasurably to diagnostic testing, to correlation of genotype with phenotype, and to insight into the pathophysiology of these disorders. In most cases, the diagnosis of muscle channelopathy is still made on clinical grounds, but is supported by ancillary laboratory and electrodiagnostic testing such as serum potassium measurement, exercise testing, repetitive nerve stimulation, needle electromyography, calculation of muscle fiber conduction velocity, or electromyography power spectra. Although provocative glucose or potassium challenges are now infrequently performed, they have contributed greatly to our understanding of the pathophysiology of these disorders, and to our ability to differentiate between periodic paralysis types. Despite considerable progress, ample opportunity remains for future clinical research, particularly in expanding genotype-phenotype correlations and in optimizing electrodiagnostic methods. With respect to diagnostic testing, there is a need for accurate, efficient, and cost-effective bedside testing, given the substantial proportion (as high as 20%) of genetically undefined cases. Even in genetically defined cases, minimal clinical expressivity due to incomplete penetrance poses a significant challenge to currently available nonmolecular testing.
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Affiliation(s)
- James C Cleland
- University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
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Fontaine B, Fournier E, Sternberg D, Vicart S, Tabti N. Hypokalemic periodic paralysis: a model for a clinical and research approach to a rare disorder. Neurotherapeutics 2007; 4:225-32. [PMID: 17395132 DOI: 10.1016/j.nurt.2007.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Rare diseases have attracted little attention in the past from physicians and researchers. The situation has recently changed for several reasons. First, patient associations have successfully advocated their cause to institutions and governments. They were able to argue that, taken together, rare diseases affect approximately 10% of the population in developed countries. Second, almost 80% of rare diseases are of genetic origin. Advances in genetics have enabled the identification of the causative genes. Unprecedented financial support has been dedicated to research on rare diseases, as well as to the development of referral centers aimed at improving the quality of care. This expenditure of resources is justified by the experience in cystic fibrosis, which demonstrated that improved care delivered by specialized referral centers resulted in a dramatic increase of life expectancy. Moreover, clinical referral centers offer the unique possibility of developing high quality clinical research studies, not otherwise possible because of the geographic dispersion of patients. This is the case in France where national referral centers for rare diseases were created, including one for muscle channelopathies. The aim of this center is to develop appropriate care, clinical research, and teaching on periodic paralysis and myotonia. In this review, we plan to demonstrate how research has improved our knowledge of hypokalemic periodic paralysis and the way we evaluate, advise, and treat patients. We also advocate for the establishment of international collaborations, which are mandatory for the follow-up of cohorts and conduct of definitive therapeutic trials in rare diseases.
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Affiliation(s)
- Bertrand Fontaine
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR S546, Paris, France.
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Tang NLS, Chow CC, Ko GTC, Tai MHL, Kwok R, Yao XQ, Cockram CS. The alpha(1S) subunit of the L-type calcium channel is not a predisposition gene for thyrotoxic periodic paralysis. Clin Endocrinol (Oxf) 2007; 66:229-34. [PMID: 17223993 DOI: 10.1111/j.1365-2265.2006.02713.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Thyrotoxic periodic paralysis (TTP) has been associated with genetic variations in the gene encoding the alpha 1 subunit of the L-type calcium channel (CACNA1S). Mutations in CACNA1S are known to account for the majority of cases of familial hypokalaemic periodic paralysis (HOKPP). In this study we have examined 48 genetic polymorphisms in the CACNA1S gene and genotyped a tagging set of representative polymorphisms to determine the role of this gene in TPP. DESIGN AND PATIENTS A genetic association study was carried out with 98 TPP patients and 162 male thyrotoxic controls. Among 47 polymorphisms evaluated for linkage disequilibrium (LD) and the spectrum of haplotypes in the Chinese population, 31 were selected as tagging single-nucleotide polymorphisms (SNPs) for genotyping the whole sample. A new genotyping protocol was used to analyse an insertion/deletion (I/D) polymorphism. RESULTS We studied the LD among 47 polymorphisms in the CACNA1S gene, which comprised a set of high-density markers with an average of one SNP every 2 kb. Subsequently, 31 tagSNPs were genotyped for all the samples. The gene is composed of three LD blocks. With this block structure, we were confident that variations of the gene were comprehensively covered by the tagSNPs. No significant association was found between the polymorphisms and TPP. CONCLUSION We established the LD structure of this calcium channel subunit gene (CACNA1S) for the first time. However, its genetic variations are not associated with TPP in Chinese patients.
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Affiliation(s)
- Nelson L S Tang
- Department of Chemical Pathology, Faculty of Medicine, The Chinese Univerisity of Hong Kong SAR, China.
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Fournier E, Viala K, Gervais H, Sternberg D, Arzel-Hézode M, Laforêt P, Eymard B, Tabti N, Willer JC, Vial C, Fontaine B. Cold extends electromyography distinction between ion channel mutations causing myotonia. Ann Neurol 2006; 60:356-65. [PMID: 16786525 DOI: 10.1002/ana.20905] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Myotonias are inherited disorders of the skeletal muscle excitability. Nondystrophic forms are caused by mutations in genes coding for the muscle chloride or sodium channel. Myotonia is either relieved or worsened by repeated exercise and can merge into flaccid weakness during exposure to cold, according to causal mutations. We designed an easy electromyography (EMG) protocol combining repeated short exercise and cold as provocative tests to discriminate groups of mutations. METHODS Surface-recorded compound muscle action potential was used to monitor muscle electrical activity. The protocol was applied on 31 unaffected control subjects and on a large population of 54 patients with chloride or sodium channel mutations known to cause the different forms of myotonia. RESULTS In patients, repeated short exercise test at room temperature disclosed three distinct abnormal patterns of compound muscle action potential changes (I-III), which matched the clinical symptoms. Combining repeated exercise with cold exposure clarified the EMG patterns in a way that enabled a clear correlation between the electrophysiological and genetic defects. INTERPRETATION We hypothesize that segregation of mutations into the different EMG patterns depended on the underlying pathophysiological mechanisms. Results allow us to suggest EMG guidelines for the molecular diagnosis, which can be used in clinical practice.
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Affiliation(s)
- Emmanuel Fournier
- Fédération de Neurophysiologie Clinique, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Université Pierre et Marie Curie, Paris.
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Hsu WC, Huang YC, Wang CW, Hsueh CH, Lai LP, Yeh JH. Paralysis periodica paramyotonica caused by SCN4A Arg1448Cys mutation. J Formos Med Assoc 2006; 105:503-7. [PMID: 16801039 DOI: 10.1016/s0929-6646(09)60191-1] [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] [Indexed: 10/20/2022] Open
Abstract
Paralysis periodica paramyotonica is an overlapping disease that shares the features of paramyotonia characteristic of paramyotonia congenita (PC) and periodic paralysis characteristic of hyperkalemic periodic paralysis. We report the case of a 23-year-old man with paralysis periodica paramyotonica. His father and a younger brother also exhibited a similar phenotype. A SCN4A Arg1448Cys mutation was detected in this family. The affected family members exhibited marked shifts in compound muscle action potential amplitudes on exercise test, and muscle weakness could be induced by potassium loading and cold exposure. This case demonstrates that SCN4A Arg1448Cys can produce paralysis periodica paramyotonica. Other genetic or environmental factors may modulate the manifestation of SCN4A Arg1448Cys mutation.
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Affiliation(s)
- Wei-Chih Hsu
- Department of Neurology, Shin-Kong WHS Memorial Hospital, Fu-Jen Catholic University, Taipei, Taiwan
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Fuglsang-Frederiksen A. The role of different EMG methods in evaluating myopathy. Clin Neurophysiol 2006; 117:1173-89. [PMID: 16516549 DOI: 10.1016/j.clinph.2005.12.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 11/22/2005] [Accepted: 12/17/2005] [Indexed: 10/25/2022]
Abstract
For the diagnosis of myopathy, EMG may have an important role along with blood tests, muscle biopsies and genetic testing. This review evaluates different EMG methods in the diagnosis of myopathy. These include manual analysis of individual motor unit potentials and multi-motor unit potential analysis sampled at weak effort. At high effort, turns-amplitude analyses such as the cloud analysis and the peak ratio analysis have a high diagnostic yield. The EMG can seldom be used to differentiate between different types of myopathy. In the channelopathies, myotonia, exercise test and cooling of the muscle are helpful. Macro-EMG, single-fibre EMG and muscle fibre conduction velocity analysis have a limited role in myopathy, but provide information about the changes seen. Analysis of the firing rate of motor units, power spectrum analysis, as well as multichannel surface EMG may have diagnostic potential in the future. EMG is of great importance in the diagnosing of patients with myopathy, preferably a needle electrode and quantitative analyses should be used. A combination of a method at weak effort as well as a method at stronger effort seems optimal.
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Affiliation(s)
- Anders Fuglsang-Frederiksen
- Department of Clinical Neurophysiology, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark.
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Fournier E. Sémiologie électrophysiologique des canalopathies musculaires suivant les mutations causales. Rev Neurol (Paris) 2005; 161:1251-9. [PMID: 16340923 DOI: 10.1016/s0035-3787(05)85237-3] [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: 11/18/2022]
Abstract
Nondystrophic myotonias and familial periodic paralyses are disorders of muscle excitability caused by mutations in genes coding for voltage-gated ion channels. Electromyographic (EMG) diagnosis of these diseases is based on needle searching of myotonic discharges and on several exercise tests, performed by surface recording of compound muscle action potential (CMAP) before and after voluntary contractions of various durations. After a short exercise test (10 seconds contraction), three abnormal changes of CMAP have been defined in muscle channelopathies: 1) appearance of repetitive discharges (post-exercise myotonic potentials, PEMP), 2) transient or long-lasting amplitude reduction, 3) long-lasting amplitude increase. These abnormalities become more marked or decline with exercise repetition (repeated brief exercise test), depending on the causal mutation. After long exercise test (5 minutes contraction), three other abnormalities of CMAP amplitude have been described: 1) immediate increase, 2) immediate decrease, 3) progressive or delayed decrease. Combining the responses to the different tests has disclosed five main EMG types of muscle channelopathies (I to V), that correlated with different pathophysiological mechanisms and with subgroups of mutations. This classification may guide molecular diagnosis in clinical practice.
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Affiliation(s)
- E Fournier
- Fédération de Neurophysiologie clinique, Groupe Hospitalier Pitié-Salpêtrière, Paris.
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Venance SL, Cannon SC, Fialho D, Fontaine B, Hanna MG, Ptacek LJ, Tristani-Firouzi M, Tawil R, Griggs RC. The primary periodic paralyses: diagnosis, pathogenesis and treatment. ACTA ACUST UNITED AC 2005; 129:8-17. [PMID: 16195244 DOI: 10.1093/brain/awh639] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Periodic paralyses (PPs) are rare inherited channelopathies that manifest as abnormal, often potassium (K)-sensitive, muscle membrane excitability leading to episodic flaccid paralysis. Hypokalaemic (HypoPP) and hyperkalaemic PP and Andersen-Tawil syndrome are genetically heterogeneous. Over the past decade mutations in genes encoding three ion channels, CACN1AS, SCN4A and KCNJ2, have been identified and account for at least 70% of the identified cases of PP and several allelic disorders. No prospective clinical studies have followed sufficiently large cohorts with characterized molecular lesions to draw precise conclusions. We summarize current knowledge of the clinical diagnosis, molecular genetics, genotype-phenotype correlations, pathophysiology and treatment in the PPs. We focus on unresolved issues including (i) Are there additional ion channel defects in cases without defined mutations? (ii) What is the mechanism for depolarization-induced weakness in Hypo PP? and finally (iii) Will detailed electrophysiological studies be able to correctly identify specific channel mutations? Understanding the pathophysiology of the potassium-sensitive PPs ought to reduce genetic complexity, allow subjects to be stratified during future clinical trials and increase the likelihood of observing true clinical effects. Ideally, therapy for the PPs will prevent attacks, avoid permanent weakness and improve quality of life. Moreover, understanding the skeletal muscle channelopathies will hopefully lead to insights into the more common central nervous system channel diseases such as migraine and epilepsy.
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Affiliation(s)
- S L Venance
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, ON, Canada.
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