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Elaraby NM, Ahmed HA, Dawoud H, Ashaat NA, Azmy A, Galal ER, Elhusseny Y, Awady HE, Metwally AM, Ashaat EA. Clinical and molecular characterization of myotonia congenita using whole-exome sequencing in Egyptian patients. Mol Biol Rep 2024; 51:766. [PMID: 38877370 DOI: 10.1007/s11033-024-09646-8] [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: 03/28/2024] [Accepted: 05/16/2024] [Indexed: 06/16/2024]
Abstract
BACKGROUND Myotonia Congenita (MC) is a rare disease classified into two major forms; Thomsen and Becker disease caused by mutations in the CLCN1 gene, which affects muscle excitability and encodes voltage-gated chloride channels (CLC-1). While, there are no data regarding the clinical and molecular characterization of myotonia in Egyptian patients. METHODS Herein, we report seven Egyptian MC patients from six unrelated families. Following the clinical diagnosis, whole-exome sequencing (WES) was performed for genetic diagnosis. Various in silico prediction tools were utilized to interpret variant pathogenicity. The candidate variants were then validated using Sanger sequencing technique. RESULTS In total, seven cases were recruited. The ages at the examination were ranged from eight months to nineteen years. Clinical manifestations included warm-up phenomenon, hand grip, and percussion myotonia. Electromyography was performed in all patients and revealed myotonic discharges. Molecular genetic analysis revealed five different variants. Of them, we identified two novel variants in the CLCN1 gene ( c.1583G > C; p.Gly528Ala and c.2203_2216del;p.Thr735ValfsTer57) and three known variants in the CLCN1 and SCN4A gene. According to in silico tools, the identified novel variants were predicted to have deleterious effects. CONCLUSIONS As the first study to apply WES among Egyptian MC patients, our findings reported two novel heterozygous variants that expand the CLCN1 mutational spectrum for MC diagnosis. These results further confirm that genetic testing is essential for early diagnosis of MC, which affects follow-up treatment and prognostic assessment in clinical practice.
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Affiliation(s)
- Nesma M Elaraby
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt.
| | - Hoda A Ahmed
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Heba Dawoud
- Pediatric Department, Tanta University, Gharbia, Egypt
| | - Neveen A Ashaat
- Professor of Human Genetics, Ain Shams University, Cairo, Egypt
| | - Ashraf Azmy
- Child Health Department, Medical Research and Clinical Studies Institute, National Research Centre, Dokki, Cairo, Egypt
| | - Eman Reda Galal
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt
| | - Yasmine Elhusseny
- Lecturer of Medical Biochemistry and Molecular Biology, School of Medicine, Newgiza University, Giza, Egypt
| | - Heba El Awady
- Pediatric Department, Fayoum University Hospitals, Fayoum, Egypt
| | - Ammal M Metwally
- Community Medicine Research Department/Medical Research, Clinical Studies Institute/National Research Centre (Affiliation ID: 60014618), Dokki, Cairo, Egypt
| | - Engy A Ashaat
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
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Li Y, Li M, Wang Z, Yang F, Wang H, Bai X, Sun B, Chen S, Huang X. Clinical and molecular characteristics of myotonia congenita in China: Case series and a literature review. Channels (Austin) 2022; 16:35-46. [PMID: 35170402 PMCID: PMC8855856 DOI: 10.1080/19336950.2022.2041292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Myotonia congenita (MC) is a rare genetic disease caused by mutations in the skeletal muscle chloride channel gene (CLCN1), encoding the voltage-gated chloride channel ClC-1 in skeletal muscle. Our study reported the clinical and molecular characteristics of six patients with MC and systematically review the literature on Chinese people. We retrospectively analyzed demographics, clinical features, family history, creatine kinase (CK), electromyography (EMG), treatment, and genotype data of our patients and reviewed the clinical data and CLCN1 mutations in literature. The median ages at examination and onset were 26.5 years (range 11–50 years) and 6.5 years (range 1.5–11 years), respectively, in our patients, and 21 years (range 3.5–65 years, n = 45) and 9 years (range 0.5–26 years, n = 50), respectively, in literature. Similar to previous reports, myotonia involved limb, lids, masticatory, and trunk muscles to varying degrees. Warm-up phenomenon (5/6), percussion myotonia (3/5), and grip myotonia (6/6) were common. Menstruation triggered myotonia in females, not observed in Chinese patients before. The proportion of abnormal CK levels (4/5) was higher than data from literature. Electromyography performed in six patients revealed myotonic changes (100%). Five novel CLCN1 mutations, including a splicing mutation (c.853 + 4A>G), a deletion mutation (c.2010_2014del), and three missense mutations (c.2527C>T, c.1727C>T, c.2017 G > C), were identified. The c.892 G > A (p.A298T) mutation was the most frequent mutation in the Chinese population. Our study expanded the clinical and genetic spectrum of patients with MC in the China. The MC phenotype in Chinese people is not different from that found in the West, while the genotype is different.
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Affiliation(s)
- Yifan Li
- Geriatric Neurological Department of the Second Medical Center & National Clinical Research Center for Geriatric Diseases, Chinese Pla General Hospital, Beijing, China
| | - Mao Li
- Department of Neurology of the First Medical Center, Chinese Pla General Hospital, Beijing, China
| | - Zhenfu Wang
- Geriatric Neurological Department of the Second Medical Center & National Clinical Research Center for Geriatric Diseases, Chinese Pla General Hospital, Beijing, China
| | - Fei Yang
- Department of Neurology of the First Medical Center, Chinese Pla General Hospital, Beijing, China
| | - Hongfen Wang
- Department of Neurology of the First Medical Center, Chinese Pla General Hospital, Beijing, China
| | - Xiujuan Bai
- Geriatric Neurological Department of the Second Medical Center & National Clinical Research Center for Geriatric Diseases, Chinese Pla General Hospital, Beijing, China
| | - Bo Sun
- Geriatric Neurological Department of the Second Medical Center & National Clinical Research Center for Geriatric Diseases, Chinese Pla General Hospital, Beijing, China
| | - Siyu Chen
- Geriatric Neurological Department of the Second Medical Center & National Clinical Research Center for Geriatric Diseases, Chinese Pla General Hospital, Beijing, China
| | - Xusheng Huang
- Department of Neurology of the First Medical Center, Chinese Pla General Hospital, Beijing, China
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Souza LS, Calyjur P, Ribeiro AF, Gurgel-Giannetti J, Pavanello RCM, Zatz M, Vainzof M. Association of Three Different Mutations in the CLCN1 Gene Modulating the Phenotype in a Consanguineous Family with Myotonia Congenita. J Mol Neurosci 2021; 71:2275-2280. [PMID: 33464536 DOI: 10.1007/s12031-020-01785-4] [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: 07/23/2020] [Accepted: 12/25/2020] [Indexed: 11/29/2022]
Abstract
Myotonia congenita is a genetic disease caused by mutations in the CLCN1 gene, which encodes for the major chloride skeletal channel ClC-1, involved in the normal repolarization of muscle action potentials and consequent relaxation of the muscle after contraction. Two allelic forms are recognized, depending on the phenotype and the inheritance pattern: the autosomal dominant Thomsen disease with milder symptoms and the autosomal recessive Becker disorder with a severe phenotype. Before the recent advances of molecular testing, the diagnosis and genetic counseling of families was a challenge due to the large number of mutations in the CLCN1 gene, found both in homozygous or in heterozygous state. Here, we studied a consanguineous family in which three members presented a variable phenotype of myotonia, associated to a combination of three different mutations in the CLCN1 gene. A pathogenic splicing site mutation which causes the skipping of exon 17 was present in homozygosis in one very severely affected son. This mutation was present in compound heterozygosis in the consanguineous parents, but interestingly it was associated to a different second variant in the other allele: c.1453 A > G in the mother and c.1842 G > C in the father. Both displayed variable, but less severe phenotypes than their homozygous son. These results highlight the importance of analyzing the combination of different variants in the same gene in particular in families with patients displaying different phenotypes. This approach may improve the diagnosis, prognosis, and genetic counseling of the involved families.
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Affiliation(s)
- Lucas Santos Souza
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Priscila Calyjur
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Antonio Fernando Ribeiro
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Juliana Gurgel-Giannetti
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
- Pediatrics Department, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - Mayana Zatz
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Mariz Vainzof
- Human Genome and stem cells Research Center, Biosciences Institute, University of São Paulo, São Paulo, Brazil.
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Rodrigues DDJ, Damasceno AD, Araújo CETD, Torelli SR, Fonseca LGH, Delfiol DJZ, Oliveira-Filho JPD, Araújo-Júnior JP, Borges AS. Hereditary myotonia in American Bulldog associated with a novel frameshift mutation in the CLCN1 gene. Neuromuscul Disord 2020; 30:991-998. [PMID: 33246886 DOI: 10.1016/j.nmd.2020.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 10/06/2020] [Accepted: 10/16/2020] [Indexed: 11/19/2022]
Abstract
Hereditary myotonia (HM) is a genetic disorder that occurs due to mutations in the chloride channel and results in delayed relaxation of the skeletal muscles. HM has been described in 12 dog breeds, and in five of them, molecular studies of this disorder were performed and mutations in the CLCN1 gene were described. In this study, an affected American Bulldog with HM clinically characterized by muscle hypertrophy, myotonic discharges, and nondystrophic myotonia with a "warm-up" phenomenon was evaluated, and the candidate canine CLCN1 gene was sequenced. The molecular analysis revealed a frameshift mutation NM_001003124.2:c.436_437insCTCT that resulted in a frameshift and a premature stop codon NP_001003124.1:pTyr146SerfsTer49 . Two aberrant alternative CLCN1 transcripts were observed in an affected dog, the expected transcript with the 4 bp insertion, NM_001003124.2:r.436_437insctct, and an unexpected transcript containing parts of intron 6 in addition to the insertion in exon 4, NM_001003124.2:[r.436_437insctct;r.774_775ins79]. In conclusion, the frameshift mutation in the CLCN1 gene is associated with autosomal recessive HM in American Bulldog and this study constitutes the first description of the disease in this breed.
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Affiliation(s)
- Daiane de Jesus Rodrigues
- Department of Veterinary Clinical Science, School of Veterinary Medicine and Animal Science, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil. Rua Prof. Dr. Walter Maurício Corrêa, s/n, Botucatu, SP, Brazil
| | - Adilson Donizeti Damasceno
- School of Veterinary and Animal Science, Universidade Federal de Goiás, Goiânia, Goiás, Brazil. Rodovia Goiânia, km 8 s/n Campus - Samambaia, Goiânia, GO 74001-970, Brazil
| | - César Erineudo Tavares de Araújo
- University Center UNILEAO, Juazeiro do Norte, Ceará, Brazil. Av. Maria Letícia Leite Pereira s/n, Lagoa Seca - Cidade Universitária, Juazeiro do Norte, CE 63040-405, Brazil
| | - Sandra Regina Torelli
- CALE - Animal Surgery and Specialized Diagnostic Laboratory, Jundiaí, São Paulo, Brazil, Rua Itália, 106 - Jardim Bonfiglioli, Jundiaí, SP 13207-280, Brazil
| | - Luine Gabriela Hilário Fonseca
- Self-employed Veterinary, Catalão, Goiás, Brazil, Rua Paraná, 330 - Nossa senhora de Fátima, Catalão, GO 75709-240, Brazil
| | - Diego José Zanzarini Delfiol
- School of Veterinary Medicine, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil, Av. Mato Grosso, 3289 - Bloco 2S - Umuarama, Uberlândia, MG 38405-314, Brazil
| | - José Paes de Oliveira-Filho
- Department of Veterinary Clinical Science, School of Veterinary Medicine and Animal Science, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil. Rua Prof. Dr. Walter Maurício Corrêa, s/n, Botucatu, SP 18618-681, Brazil
| | - João Pessoa Araújo-Júnior
- Institute of Biotechnology, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil. Alameda das Tecomarias, s/n - Chácara Capão Bonito, Botucatu, SP 18607-440, Brazil
| | - Alexandre Secorun Borges
- Department of Veterinary Clinical Science, School of Veterinary Medicine and Animal Science, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil. Rua Prof. Dr. Walter Maurício Corrêa, s/n, Botucatu, SP 18618-681, Brazil.
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Orsini C, Petillo R, D'Ambrosio P, Ergoli M, Picillo E, Scutifero M, Passamano L, De Luca A, Politano L. CLCN1 Molecular Characterization in 19 South-Italian Patients With Dominant and Recessive Type of Myotonia Congenita. Front Neurol 2020; 11:63. [PMID: 32117024 PMCID: PMC7016095 DOI: 10.3389/fneur.2020.00063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/17/2020] [Indexed: 11/13/2022] Open
Abstract
Myotonia congenita is a genetic disease characterized by impaired muscle relaxation after forceful contraction (myotonia). It is caused by mutations in the CLCN1 gene, encoding the voltage-gated chloride channel of skeletal muscle, ClC-1. According to the pattern of inheritance, two distinct clinical forms have been described, Thomsen disease, inherited as an autosomal dominant trait and Becker disease inherited as an autosomal recessive trait. We report genetic and clinical data concerning 19 patients−13 familial and six isolated cases—all but one originating from the Campania Region, in southern Italy. Twelve patients (63.2%) present Becker type myotonia and 7 (36.8%) Thomsen type. Sex ratio M:F in Becker type is 6:6, while in Thomsen myotonia 4:3. The age of onset of the disease ranged from 2 to 15 years in Becker patients, and from 4 to 20 years in Thomsen. Overall 18 mutations were identified, 10 located in the coding part of the gene (exons 1, 3, 4, 5, 7, 8, 13, 15, 21, 22), and four in the intron part (introns 1, 2, 10, 18). All the exon mutations but two were missense mutations. Some of them, such as c.2551 G > A, c.817G > A and c.86A > C recurred more frequently. About 70% of mutations was inherited with an autosomal recessive pattern, two (c.86A and c.817G>A) with both mechanisms. Three novel mutations were identified, never described in the literature: p.Gly276Ser, p.Phe486Ser, and p.Gln812*, associated with Becker phenotype. Furthermore, we identified three CLCN1 mutations—c.86A>C + c.2551G > A, c.313C > T + c.501C > G and 899G > A + c.2284+5C > T, two of them inherited in cis on the same allele, in three unrelated families. The concomitant occurrence of both clinical pictures—Thomsen and Becker—was observed in one family. Intra-familial phenotypic variability was observed in two families, one with Becker phenotype, and one with Thomsen disease. In the latter an incomplete penetrance was hypothesized.
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Affiliation(s)
- Chiara Orsini
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Roberta Petillo
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Paola D'Ambrosio
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Manuela Ergoli
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Esther Picillo
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Marianna Scutifero
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Luigia Passamano
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Alessandro De Luca
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Luisa Politano
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
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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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Mishra A, Dave N, Pandya HV, Sapre CM, Chaudhary S. Hyperkalemic paralysis in primary adrenal insufficiency. Indian J Crit Care Med 2014; 18:527-9. [PMID: 25136192 PMCID: PMC4134627 DOI: 10.4103/0972-5229.138157] [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] [Indexed: 12/03/2022] Open
Abstract
Hyperkalemic paralysis due to Addison's disease is rare, and potentially life-threatening entity presenting with flaccid motor weakness. This case under discussion highlights Hyperkalemic paralysis as initial symptomatic manifestation of primary adrenal insufficiency.
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Cherian A, Baheti NN, Iype T. Electrophysiological study in neuromuscular junction disorders. Ann Indian Acad Neurol 2013; 16:34-41. [PMID: 23661960 PMCID: PMC3644779 DOI: 10.4103/0972-2327.107690] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/13/2011] [Accepted: 07/01/2012] [Indexed: 11/20/2022] Open
Abstract
This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG) helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS). SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.
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Affiliation(s)
- Ajith Cherian
- Department of Neurology, Government Medical College, Trivandrum, Kerala, India
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9
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Naik KR, Saroja AO, Khanpet MS. Reversible electrophysiological abnormalities in acute secondary hyperkalemic paralysis. Ann Indian Acad Neurol 2013; 15:339-43. [PMID: 23349611 PMCID: PMC3548384 DOI: 10.4103/0972-2327.104354] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/14/2012] [Accepted: 06/23/2012] [Indexed: 11/26/2022] Open
Abstract
Hyperkalemia manifests clinically with acute neuromuscular paralysis, which can simulate Guillain Barré syndrome (GBS) and other causes of acute flaccid paralysis. Primary hyperkalemic paralysis occurs from genetic defects in the sodium channel, and secondary hyperkalemic paralysis (SHP) from diverse causes including renal dysfunction, potassium retaining drugs, Addison's disease, etc. Clinical characteristics of SHP have been addressed in a number of publications. However, electrophysiological evaluations of these patients during neuromuscular paralysis are infrequently reported and have demonstrated features of demyelination. The clinical features and electrophysiological abnormalities in secondary hyperkalemia mimic GBS, and pose diagnostic challenges. We report the findings of nerve conduction studies in a middle-aged man who was admitted with rapidly reversible acute quadriplegia resulting from secondary hyperkalemic paralysis.
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Affiliation(s)
- Karkal R Naik
- Department of Neurology, KLE University's Jawaharlal Nehru Medical College and KLES Dr. Prabhakar Kore Hospital and MRC, Nehrunagar, Belgaum, India
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10
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Wijnberg ID, Owczarek-Lipska M, Sacchetto R, Mascarello F, Pascoli F, Grünberg W, van der Kolk JH, Drögemüller C. A missense mutation in the skeletal muscle chloride channel 1 (CLCN1) as candidate causal mutation for congenital myotonia in a New Forest pony. Neuromuscul Disord 2012; 22:361-7. [DOI: 10.1016/j.nmd.2011.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 09/26/2011] [Accepted: 10/03/2011] [Indexed: 11/26/2022]
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