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Nelson TS, Duran P, Calderon-Rivera A, Gomez K, Loya-Lopez S, Khanna R. Mouse models of non-dystrophic and dystrophic myotonia exhibit nociplastic pain-like behaviors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.19.599732. [PMID: 38948724 PMCID: PMC11212949 DOI: 10.1101/2024.06.19.599732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Pain is a prominent and debilitating symptom in myotonic disorders, yet its physiological mechanisms remain poorly understood. This study assessed preclinical pain-like behavior in murine models of pharmacologically induced myotonia and myotonic dystrophy type 1 (DM1). In both myotonia congenita and DM1, impairment of the CLCN1 gene, which encodes skeletal muscle voltage-gated CLC-1 chloride channels, reduces chloride ion conductance in skeletal muscle cells, leading to prolonged muscle excitability and delayed relaxation after contraction. We used the CLC-1 antagonist anthracene-9-carboxylic acid (9-AC) at intraperitoneal doses of 30 or 60 mg/kg and HSA LR20b DM1 mice to model CLC-1-induced myotonia. Our experimental approach included in vivo pain behavioral testing, ex vivo calcium imaging, and whole-cell current-clamp electrophysiology in mouse dorsal root ganglion (DRG) neurons. A single injection of 9-AC induced myotonia in mice, which persisted for several hours and resulted in long-lasting allodynic pain-like behavior. Similarly, HSA LR20b mice exhibited both allodynia and hyperalgesia. Despite these pain-like behaviors, DRG neurons did not show signs of hyperexcitability in either myotonic model. These findings suggest that myotonia induces nociplastic pain-like behavior in preclinical rodents, likely through central sensitization mechanisms rather than peripheral sensitization. This study provides insights into the pathophysiology of pain in myotonic disorders and highlights the potential of using myotonic mouse models to explore pain mechanisms and assess novel analgesics. Future research should focus on the central mechanisms involved in myotonia-induced pain and develop targeted therapies to alleviate this significant clinical burden.
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Affiliation(s)
- Tyler S. Nelson
- Department of Pharmacology and Therapeutics, McKnight Brain Institute, and Pain and Addiction Therapeutics (PATH) Collaboratory, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Paz Duran
- Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY 10010, USA
| | - Aida Calderon-Rivera
- Department of Pharmacology and Therapeutics, McKnight Brain Institute, and Pain and Addiction Therapeutics (PATH) Collaboratory, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Kimberly Gomez
- Department of Pharmacology and Therapeutics, McKnight Brain Institute, and Pain and Addiction Therapeutics (PATH) Collaboratory, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Santiago Loya-Lopez
- Department of Pharmacology and Therapeutics, McKnight Brain Institute, and Pain and Addiction Therapeutics (PATH) Collaboratory, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Rajesh Khanna
- Department of Pharmacology and Therapeutics, McKnight Brain Institute, and Pain and Addiction Therapeutics (PATH) Collaboratory, University of Florida College of Medicine, Gainesville, FL 32610, USA
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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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Doughty CT, Schaefer PW, Brizzi K, Linnoila JJ. Case 14-2024: A 30-Year-Old Woman with Back Pain, Leg Stiffness, and Falls. N Engl J Med 2024; 390:1712-1719. [PMID: 38718362 DOI: 10.1056/nejmcpc2312733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Affiliation(s)
- Christopher T Doughty
- From the Department of Neurology, Brigham and Women's Hospital (C.T.D.), the Departments of Radiology (P.W.S.), Medicine (K.B.), and Neurology (K.B., J.J.L.), Massachusetts General Hospital, and the Departments of Neurology (C.T.D., K.B., J.J.L.), Radiology (P.W.S.), and Medicine (K.B., J.J.L.), Harvard Medical School - all in Boston
| | - Pamela W Schaefer
- From the Department of Neurology, Brigham and Women's Hospital (C.T.D.), the Departments of Radiology (P.W.S.), Medicine (K.B.), and Neurology (K.B., J.J.L.), Massachusetts General Hospital, and the Departments of Neurology (C.T.D., K.B., J.J.L.), Radiology (P.W.S.), and Medicine (K.B., J.J.L.), Harvard Medical School - all in Boston
| | - Kate Brizzi
- From the Department of Neurology, Brigham and Women's Hospital (C.T.D.), the Departments of Radiology (P.W.S.), Medicine (K.B.), and Neurology (K.B., J.J.L.), Massachusetts General Hospital, and the Departments of Neurology (C.T.D., K.B., J.J.L.), Radiology (P.W.S.), and Medicine (K.B., J.J.L.), Harvard Medical School - all in Boston
| | - Jenny J Linnoila
- From the Department of Neurology, Brigham and Women's Hospital (C.T.D.), the Departments of Radiology (P.W.S.), Medicine (K.B.), and Neurology (K.B., J.J.L.), Massachusetts General Hospital, and the Departments of Neurology (C.T.D., K.B., J.J.L.), Radiology (P.W.S.), and Medicine (K.B., J.J.L.), Harvard Medical School - all in Boston
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4
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Beecher G, Gavrilova RH, Mandrekar J, Naddaf E. Mitochondrial myopathies diagnosed in adulthood: clinico-genetic spectrum and long-term outcomes. Brain Commun 2024; 6:fcae041. [PMID: 38434220 PMCID: PMC10906953 DOI: 10.1093/braincomms/fcae041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 12/14/2023] [Accepted: 02/12/2024] [Indexed: 03/05/2024] Open
Abstract
Mitochondrial myopathies are frequently recognized in childhood as part of a broader multisystem disorder and often overlooked in adulthood. Herein, we describe the phenotypic and genotypic spectrum and long-term outcomes of mitochondrial myopathies diagnosed in adulthood, focusing on neuromuscular features, electrodiagnostic and myopathological findings and survival. We performed a retrospective chart review of adult patients diagnosed with mitochondrial myopathy at Mayo Clinic (2005-21). We identified 94 patients. Median time from symptom onset to diagnosis was 11 years (interquartile range 4-21 years). Median age at diagnosis was 48 years (32-63 years). Primary genetic defects were identified in mitochondrial DNA in 48 patients (10 with single large deletion, 38 with point mutations) and nuclear DNA in 29. Five patients had multiple mitochondrial DNA deletions or depletion without nuclear DNA variants. Twelve patients had histopathological features of mitochondrial myopathy without molecular diagnosis. The most common phenotypes included multisystem disorder (n = 30); mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (14); limb myopathy (13); chronic progressive external ophthalmoplegia (12); and chronic progressive external ophthalmoplegia-plus (12). Isolated skeletal muscle manifestations occurred in 27%. Sixty-nine per cent had CNS and 21% had cardiac involvement. Mutations most frequently involved MT-TL1 (27) and POLG (17); however, a wide spectrum of established and novel molecular defects, with overlapping phenotypes, was identified. Electrodiagnostic studies identified myopathy (77%), fibrillation potentials (27%) and axonal peripheral neuropathy (42%, most common with nuclear DNA variants). Among 42 muscle biopsies available, median percentage counts were highest for cytochrome C oxidase negative fibres (5.1%) then ragged blue (1.4%) and ragged red fibres (0.5%). Skeletal muscle weakness was mild and slowly progressive (decline in strength summated score of 0.01/year). Median time to gait assistance was 5.5 years from diagnosis and 17 years from symptom onset. Thirty patients died, with median survival of 33.4 years from symptom onset and 10.9 years from diagnosis. Median age at death was 55 years. Cardiac involvement was associated with increased mortality [hazard ratio 2.36 (1.05, 5.29)]. There was no difference in survival based on genotype or phenotype. Despite the wide phenotypic and genotypic spectrum, mitochondrial myopathies in adults share similar features with slowly progressive limb weakness, contrasting with common multiorgan involvement and high mortality.
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Affiliation(s)
- Grayson Beecher
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2G3
| | - Ralitza H Gavrilova
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Jay Mandrekar
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Elie Naddaf
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
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Vinci M, Vitello GA, Greco D, Treccarichi S, Ragalmuto A, Musumeci A, Fallea A, Federico C, Calì F, Saccone S, Elia M. Next Generation Sequencing and Electromyography Reveal the Involvement of the P2RX6 Gene in Myopathy. Curr Issues Mol Biol 2024; 46:1150-1163. [PMID: 38392191 PMCID: PMC10887510 DOI: 10.3390/cimb46020073] [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: 12/27/2023] [Revised: 01/18/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Ion channelopathies result from impaired ion channel protein function, due to mutations affecting ion transport across cell membranes. Over 40 diseases, including neuropathy, pain, migraine, epilepsy, and ataxia, are associated with ion channelopathies, impacting electrically excitable tissues and significantly affecting skeletal muscle. Gene mutations affecting transmembrane ionic flow are strongly linked to skeletal muscle disorders, particularly myopathies, disrupting muscle excitability and contraction. Electromyography (EMG) analysis performed on a patient who complained of weakness and fatigue revealed the presence of primary muscular damage, suggesting an early-stage myopathy. Whole exome sequencing (WES) did not detect potentially causative variants in known myopathy-associated genes but revealed a novel homozygous deletion of the P2RX6 gene likely disrupting protein function. The P2RX6 gene, predominantly expressed in skeletal muscle, is an ATP-gated ion channel receptor belonging to the purinergic receptors (P2RX) family. In addition, STRING pathways suggested a correlation with more proteins having a plausible role in myopathy. No previous studies have reported the implication of this gene in myopathy. Further studies are needed on patients with a defective ion channel pathway, and the use of in vitro functional assays in suppressing P2RX6 gene expression will be required to validate its functional role.
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Affiliation(s)
| | | | | | | | | | | | | | - Concetta Federico
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
| | | | - Salvatore Saccone
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
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Yi H, Liu CX, Ye SX, Liu YL. Special electromyographic features in a child with paramyotonia congenita: A case report and review of literature. World J Clin Cases 2024; 12:587-595. [PMID: 38322461 PMCID: PMC10841953 DOI: 10.12998/wjcc.v12.i3.587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/04/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Paramyotonia congenita (PMC) stands as a rare sodium channelopaty of skeletal muscle, initially identified by Eulenburg. The identification of PMC often relies on electromyography (EMG), a diagnostic technique. The child's needle EMG unveiled trains of myotonic discharges with notably giant amplitudes, alongside irregular wave trains of myotonic discharges. This distinctive observation had not surfaced in earlier studies. CASE SUMMARY We report the case of a 3-year-old female child with PMC, who exhibited laryngeal stridor, muffled speech, myotonia from birth. Cold, exposure to cool water, crying, and physical activity exacerbated the myotonia, which was relieved in warmth, yet never normalized. Percussion myotonia was observable in bilateral biceps. Myotonia symptoms remained unchanged after potassium-rich food consumption like bananas. Hyperkalemic periodic paralysis was excluded. Cranial magnetic resonance imaging yielded normal results. Blood potassium remained within normal range, while creatine kinase showed slight elevation. Exome-wide genetic testing pinpointed a heterozygous mutation on chromosome SCN4A: c.3917G>A (p.G1306E). After a six-month mexiletine regimen, symptoms alleviated. CONCLUSION In this case revealed the two types of myotonic discharges, and had not been documented in other studies. We underscore two distinctive features: Giant-amplitude potentials and irregular waves.
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Affiliation(s)
- Hui Yi
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
| | - Chen-Xiang Liu
- Department of Neuroelectrophysiology, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao 266000, Shandong Province, China
| | - Shu-Xin Ye
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
| | - Yu-Lin Liu
- Department of Neuroelectrophysiology, Qilu Children’s Hospital of Shandong University, Jinan 250000, Shandong Province, China
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Lidonnici D, Brambilla P, Ravasio R, Zozulya-Weidenfeller A, Beiderbeck A, van Aswegen M, Oliveira R, Sansone VA. Expert Insights from a Delphi-driven Neurologists' Panel: Real-world Mexiletine use in Patients with Myotonic Disorders in Italy. J Neuromuscul Dis 2024; 11:411-423. [PMID: 38306059 DOI: 10.3233/jnd-230115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Background Myotonic disorders, such as non-dystrophic myotonias (NDMs) and myotonic dystrophies (DMs) are characterized by a delay in muscle relaxation after a contraction stimulus. There is general consensus that protocols to treat myotonia need to be implemented. Objective Mexiletine is the only pharmacological agent approved for the symptomatic treatment of myotonia in adult patients with NDM and is considered to be the first-line treatment for DMs; however, its production in Italy was halted in 2022 making its availability to patients problematic. Methods A panel of 8 Italian neurologists took part in a two-round Delphi panel between June and October 2022, analyzing the current use of mexiletine in Italian clinical practice. Results The panelists assist 1126 patients (69% DM type1, 18% NDM and 13% DM type2). Adult NDM patients receive, on average, 400-600 mg of mexiletine hydrochloride (HCl) while adult DM patients receive 100-600 mg, per day in the long-term. The severity of symptoms is considered the main reason to start mexiletine treatment for both NDM and DM patients. Mexiletine is reckoned to have a clinical impact for both NDM and DM patients, but currently drug access is problematic. Conclusions Mexiletine treatment is recognized to have a role in the reduction of the symptomatic burden for NDM and DM patients. Patient management could be improved by facilitating access to therapy and developing new drug formulations.
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Affiliation(s)
| | | | | | | | | | | | | | - Valeria A Sansone
- The NEMO Center, Neurorehabilitation Unit, University of Milan, ASST Niguarda Hospital, Milan, Italy
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Velardo D, Antognozzi S, Rimoldi M, Pagliarani S, Cogiamanian F, Barbieri S, Corti S, Comi GP, Ronchi D. Case report: Clinical and molecular characterization of two siblings affected by Brody myopathy. Front Neurol 2023; 14:1170071. [PMID: 37332993 PMCID: PMC10272758 DOI: 10.3389/fneur.2023.1170071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 05/16/2023] [Indexed: 06/20/2023] Open
Abstract
Exercise-induced muscle stiffness is the hallmark of Brody disease, an autosomal recessive myopathy due to biallelic pathogenic variants in ATP2A1, encoding the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase SERCA1. About 40 patients have been reported so far. Our knowledge about the natural history of this disorder, genotype-phenotype correlations and the effect of symptomatic treatment is partial. This results in incomplete recognition and underdiagnosis of the disease. Here, we report the clinical, instrumental, and molecular features of two siblings presenting childhood-onset exercise-induced muscle stiffness without pain. Both the probands display difficulty in climbing stairs and running, frequent falls, delayed muscle relaxation after exertion. Cold temperatures worsen these symptoms. No myotonic discharges were observed at electromyography. Whole Exome Sequencing analysis in the probands revealed the presence of two ATP2A1 variants: the previously reported frameshift microdeletion c.2464delC and the likely pathogenic novel splice-site variant c.324 + 1G > A, whose detrimental effect was demonstrated in ATP2A1 transcript analysis. The bi-allelic inheritance was verified by Sanger sequencing in the unaffected parents. This study expands the molecular defects associated with Brody myopathy.
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Affiliation(s)
- Daniele Velardo
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Sara Antognozzi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Martina Rimoldi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Serena Pagliarani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Filippo Cogiamanian
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurophysiology Unit, Milan, Italy
| | - Sergio Barbieri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurophysiology Unit, Milan, Italy
| | - Stefania Corti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Giacomo Pietro Comi
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Dario Ronchi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
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Ivanovic V, Peric S, Pesovic J, Tubic R, Bozovic I, Petrovic Djordjevic I, Savic-Pavicevic D, Meola G, Rakocevic-Stojanovic V. Clinical score for early diagnosis of myotonic dystrophy type 2. Neurol Sci 2023; 44:1059-1067. [PMID: 36401657 PMCID: PMC9925479 DOI: 10.1007/s10072-022-06507-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/12/2022] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Myotonic dystrophy type 2 (DM2) is a rare, multisystemic, autosomal dominant disease with highly variable clinical presentation. DM2 is considered to be highly underdiagnosed. OBJECTIVE The aim of this study was to determine which symptoms, signs, and diagnostic findings in patients referred to neurological outpatient units are the most indicative to arouse suspicion of DM2. We tried to make a useful and easy-to-administer clinical scoring system for early diagnosis of DM2-DM2 early diagnosis score (DM2-EDS). PATIENTS AND METHODS Two hundred ninety-one patients with a clinical suspicion of DM2 were included: 69 were genetically confirmed to have DM2, and 222 patients were DM2 negative. Relevant history, neurological, and paraclinical data were obtained from the electronic medical records. RESULTS The following parameters appeared as significant predictors of DM2 diagnosis: cataracts (beta = 0.410, p < 0.001), myotonia on needle EMG (beta = 0.298, p < 0.001), hand tremor (beta = 0.211, p = 0.001), positive family history (beta = 0.171, p = 0.012), and calf hypertrophy (beta = 0.120, p = 0.043). In the final DM2-EDS, based on the beta values, symptoms were associated with the following values: cataracts (present 3.4, absent 0), myotonia (present 2.5, absent 0), tremor (present 1.7, absent 0), family history (positive 1.4, negative 0), and calf hypertrophy (present 1.0, absent 0). A cut-off value on DM2-EDS of 3.25 of maximum 10 points had a sensitivity of 84% and specificity of 81% to diagnose DM2. CONCLUSION Significant predictors of DM2 diagnosis in the neurology outpatient unit were identified. We made an easy-to-administer DM2-EDS score for early diagnosis of DM2.
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Affiliation(s)
- Vukan Ivanovic
- University of Belgrade - Faculty of Medicine, University Clinical Center of Serbia - Neurology Clinic, Dr. Subotic Street, 11 000, Belgrade, Serbia
| | - Stojan Peric
- University of Belgrade - Faculty of Medicine, University Clinical Center of Serbia - Neurology Clinic, Dr. Subotic Street, 11 000, Belgrade, Serbia.
| | - Jovan Pesovic
- University of Belgrade - Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Radoje Tubic
- Institute of Oncology and Radiology of Serbia, Belgrade, Serbia
| | - Ivo Bozovic
- University of Belgrade - Faculty of Medicine, University Clinical Center of Serbia - Neurology Clinic, Dr. Subotic Street, 11 000, Belgrade, Serbia
| | - Ivana Petrovic Djordjevic
- University of Belgrade - Faculty of Medicine, University Clinical Center of Serbia - Cardiology Clinic, Belgrade, Serbia
| | - Dusanka Savic-Pavicevic
- University of Belgrade - Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences - Casa Di Cura del Policlinico, Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Vidosava Rakocevic-Stojanovic
- University of Belgrade - Faculty of Medicine, University Clinical Center of Serbia - Neurology Clinic, Dr. Subotic Street, 11 000, Belgrade, Serbia
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Mohammed SR, Gafoor S, Panday A. Acute myotonic reaction during succinylcholine anaesthesia. Pract Neurol 2023; 23:74-77. [PMID: 36192135 DOI: 10.1136/pn-2022-003352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2022] [Indexed: 02/02/2023]
Abstract
A 21-year-old woman developed an acute myotonic reaction while undergoing anaesthesia using succinylcholine. Examination later showed she had shoulder, neck and calf hypertrophy, bilateral symmetrical ptosis and eyelid, handgrip and percussion myotonia. Peripheral neurophysiology studies identified significant, continuous myotonic discharges in both upper and lower limbs. Genetic analysis identified a c.3917G>A (p.Gly1306Glu) mutation in the SCN4A gene, confirming a diagnosis of sodium channel myotonia. Succinylcholine and other depolarising agents can precipitate life-threatening acute myotonic reactions when given to patients with myotonia. Patients with neuromuscular disorders are at an increased risk of perioperative anaesthetic complications. We report a woman who developed an acute myotonic reaction whilst undergoing anaesthesia, in the context of an unrecognised myotonic disorder. We then discuss an approach to the diagnosis of myotonic disorders.
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Affiliation(s)
- Saeed Rashaad Mohammed
- Department of Clinical Medical Sciences, The University of the West Indies at St Augustine Faculty of Medical Sciences, St Augustine, Trinidad and Tobago
| | - Stefan Gafoor
- Department of Medicine, Eric Williams Medical Sciences Complex Compound, Champ Fleurs, Trinidad and Tobago
| | - Avidesh Panday
- Department of Clinical Medical Sciences, The University of the West Indies at St Augustine Faculty of Medical Sciences, St Augustine, Trinidad and Tobago
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Díaz-Manera J, Urtizberea JA, Schey C, Kole A, von Gallwitz P, Whiting A, Foerster D, Zozulya-Weidenfeller A. Impact of restricted access to, and low awareness of, mexiletine on people with myotonia: a real-world European survey. Neuromuscul Disord 2023; 33:208-217. [PMID: 36706619 DOI: 10.1016/j.nmd.2022.12.008] [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: 04/28/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Although mexiletine effectively treats myotonia, supply disruptions affected Europe between 2008-2018. MyoPath was a mixed-methods, cross-sectional, market research survey conducted January-June 2018 to evaluate consequences of limited access to/awareness of mexiletine in people with myotonia. Part A: qualitative structured interviews (clinicians; advocates for adult patients); Part B: quantitative online questionnaire completed by people with self-reported history of myotonia. Part A: Interviews (clinicians, n=12; patient advocates, n=5; 12 countries) indicated poor mexiletine awareness among general neurologists. Patients chose between living with myotonia (other treatments were generally unsatisfactory) or importing mexiletine. Part B: Questionnaire respondents, myotonic dystrophy (DM)1, n=213; DM2, n=128; non-dystrophic myotonia (NDM), n=41; other n=8; (11 countries). Of the respondents, 76/390 (20%) people with awareness of/access to mexiletine described profound improvements in myotonia and health-related quality of life following treatment. Respondents with NDM had greatest mexiletine experience (n=28/41). Mexiletine was associated with fewer falls, less muscle stiffness, increased mobility. Treatment interruptions worsened myotonia and were associated with fatigue, pain, dysphagia, breathing difficulty, impaired digestion, poor sleep. However, 36/54 (67%) of currently treated people expressed anxiety about mexiletine's availability: this finding was expected (MyoPath was undertaken before mexiletine's approval in NDM). MyoPath provides the largest European exploration of patients' views regarding impact of mexiletine on myotonia. Anticipated effects of mexiletine differ between people with different myotonic disorders: myotonia is the main symptom in NDM but one of many potential symptoms affecting those with DM. Nevertheless, findings indicate substantial harm caused to people with myotonia when mexiletine awareness/access is limited.
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Affiliation(s)
- Jordi Díaz-Manera
- John Walton Muscular Dystrophy Research Centre, Newcastle University International Centre for Life, Newcastle upon Tyne, United Kingdom.
| | | | - Carina Schey
- Department of Epidemiology, University of Groningen, Groningen, the Netherlands
| | - Anna Kole
- admedicum® Business for Patients GmbH & Co KG, Cologne, Germany
| | | | - Amy Whiting
- admedicum® Business for Patients GmbH & Co KG, Cologne, Germany
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12
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Trivedi JR. Muscle Channelopathies. Continuum (Minneap Minn) 2022; 28:1778-1799. [PMID: 36537980 DOI: 10.1212/con.0000000000001183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE OF REVIEW This article describes the clinical features, diagnosis, pathophysiology, and management of nondystrophic myotonia and periodic paralysis. RECENT FINDINGS An increasing awareness exists about the genotype-phenotype overlap in skeletal muscle channelopathies, and thus genetic testing is needed to make a definitive diagnosis. Electrodiagnostic testing in channelopathies is highly specialized with significant overlap in various mutation subtypes. Randomized clinical trials have now been conducted in these disorders with expanded treatment options for patients with muscle channelopathies. SUMMARY Skeletal muscle channelopathies are rare heterogeneous conditions characterized by lifelong symptoms that require a comprehensive management plan that includes pharmacologic and nonpharmacologic interventions. The significant variability in biophysical features of various mutations, coupled with the difficulties of performing clinical trials in rare diseases, makes it challenging to design and implement treatment trials for muscle channelopathies.
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13
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Văcăraș V, Elian H, Isachi ID, Văcăraș C, Mureșanu DF. Steinert's disease, from assumption to certainty in neurological practice. BALNEO AND PRM RESEARCH JOURNAL 2022. [DOI: 10.12680/balneo.2022.515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Steinert’s disease, or myotonic dystrophy type 1 (MD1), is the most prevalent myopathy in adults. We report the case of a patient who was admitted to the Neurology Department for the progressive decrease in muscle strength in the lower limbs bilaterally. Symptoms began about 18 months before the presentation to the Neurology Department. On the elec-troneurographic examination, specific features for myotonic dystrophy type 1 were described, confirmed later by the genetic test.
Keywords: Steinert’s disease, Paraparesis, Multisystemic Disease, Neurology.
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Affiliation(s)
- Vitalie Văcăraș
- Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania 2 Cluj-Napoca County Emergency Hospital, Neurology II Department, Cluj-Napoca, Romania
| | - Hapca Elian
- Cluj-Napoca County Emergency Hospital, Neurology II Department, Cluj-Napoca, Romania
| | - Ionuț-Dănuț Isachi
- Cluj-Napoca County Emergency Hospital, Neurology II Department, Cluj-Napoca, Romania
| | - Cristiana Văcăraș
- Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Dafin Fior Mureșanu
- Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania 2 Cluj-Napoca County Emergency Hospital, Neurology II Department, Cluj-Napoca, Romania
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14
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Fujikawa H, Hayashi D, Sato M. Myotonic Dystrophy Type 1: A Snap Diagnosis During a Medical Checkup. Am J Med Sci 2022; 364:e8-e9. [PMID: 35038421 DOI: 10.1016/j.amjms.2022.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 12/21/2021] [Accepted: 01/04/2022] [Indexed: 11/01/2022]
Affiliation(s)
- Hirohisa Fujikawa
- Department of Medical Education Studies, International Research Center for Medical Education, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan; Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan.
| | - Daigo Hayashi
- Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan
| | - Mariko Sato
- Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan
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15
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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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16
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Matthews E, Holmes S, Fialho D. Skeletal muscle channelopathies: a guide to diagnosis and management. Pract Neurol 2021; 21:196-204. [PMID: 33563766 DOI: 10.1136/practneurol-2020-002576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2020] [Indexed: 12/17/2022]
Abstract
Skeletal muscle channelopathies are a group of rare episodic genetic disorders comprising the periodic paralyses and the non-dystrophic myotonias. They may cause significant morbidity, limit vocational opportunities, be socially embarrassing, and sometimes are associated with sudden cardiac death. The diagnosis is often hampered by symptoms that patients may find difficult to describe, a normal examination in the absence of symptoms, and the need to interpret numerous tests that may be normal or abnormal. However, the symptoms respond very well to holistic management and pharmacological treatment, with great benefit to quality of life. Here, we review when to suspect a muscle channelopathy, how to investigate a possible case and the options for therapy once a diagnosis is made.
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Affiliation(s)
- Emma Matthews
- Atkinson-Morley Neuromuscular Centre, St George's University Hospitals NHS Foundation Trust, London, UK
- Department of Neuromuscular Diseases, UCL, Institute of Neurology, London, UK
| | - Sarah Holmes
- Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, UK
| | - Doreen Fialho
- Department of Neuromuscular Diseases, UCL, Institute of Neurology, London, UK
- Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, UK
- Department of Clinical Neurophysiology, King's College Hospital NHS Foundation Trust, London, UK
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17
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Danti FR, Invernizzi F, Moroni I, Garavaglia B, Nardocci N, Zorzi G. Pediatric Paroxysmal Exercise-Induced Neurological Symptoms: Clinical Spectrum and Diagnostic Algorithm. Front Neurol 2021; 12:658178. [PMID: 34140924 PMCID: PMC8203909 DOI: 10.3389/fneur.2021.658178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/21/2021] [Indexed: 12/18/2022] Open
Abstract
Paroxysmal exercise-induced neurological symptoms (PENS) encompass a wide spectrum of clinical phenomena commonly presenting during childhood and characteristically elicited by physical exercise. Interestingly, few shared pathogenetic mechanisms have been identified beyond the well-known entity of paroxysmal exercise-induced dyskinesia, PENS could be part of more complex phenotypes including neuromuscular, neurodegenerative, and neurometabolic disease, epilepsies, and psychogenetic disorders. The wide and partially overlapping phenotypes and the genetic heterogeneity make the differential diagnosis frequently difficult and delayed; however, since some of these disorders may be treatable, a prompt diagnosis is mandatory. Therefore, an accurate characterization of these symptoms is pivotal for orienting more targeted biochemical, radiological, neurophysiological, and genetic investigations and finally treatment. In this article, we review the clinical, genetic, pathophysiologic, and therapeutic landscape of paroxysmal exercise induced neurological symptoms, focusing on phenomenology and differential diagnosis.
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Affiliation(s)
- Federica Rachele Danti
- Unit of Child Neurology, Department of Pediatric Neuroscience, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Federica Invernizzi
- Unit of Medical Genetics and Neurogenetics, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico C. Besta, Milan, Italy
| | - Isabella Moroni
- Unit of Child Neurology, Department of Pediatric Neuroscience, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Barbara Garavaglia
- Unit of Medical Genetics and Neurogenetics, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico C. Besta, Milan, Italy
| | - Nardo Nardocci
- Unit of Child Neurology, Department of Pediatric Neuroscience, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico Carlo Besta, Milan, Italy
| | - Giovanna Zorzi
- Unit of Child Neurology, Department of Pediatric Neuroscience, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Neurologico Carlo Besta, Milan, Italy
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18
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Fujikawa H, Hayashi D, Saito M. Myotonic dystrophy type 1 presenting with grip myotonia and functional improvement after rehabilitation. BMJ Case Rep 2021; 14:e241552. [PMID: 33849876 PMCID: PMC8051416 DOI: 10.1136/bcr-2021-241552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2021] [Indexed: 11/03/2022] Open
Affiliation(s)
- Hirohisa Fujikawa
- Department of Medical Education Studies, International Research Center for Medical Education, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan
| | - Daigo Hayashi
- Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan
| | - Minoru Saito
- Department of Internal Medicine, Suwa Central Hospital, Chino, Nagano, Japan
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19
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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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20
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Ebert SE, Cartwright MS. Clinical Reasoning: A child with muscle stiffness. Neurology 2020; 95:e1609-e1612. [DOI: 10.1212/wnl.0000000000009459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Abstract
Skeletal muscle channelopathies are rare genetic neuromuscular conditions that include the nondystrophic myotonias and periodic paralyses. They cause disabling muscle symptoms and can limit educational potential, work opportunities, socialization, and quality of life. Effective therapy is available, making it essential to recognize and treat this group of disorders. Here, the authors highlight important aspects regarding diagnosis and management using illustrative case reports.
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Affiliation(s)
- Vinojini Vivekanandam
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Pinki Munot
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
| | - Emma Matthews
- Department of Neuromuscular Diseases, Queen Square Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK.
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22
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Meyer AP, Roggenbuck J, LoRusso S, Kissel J, Smith RM, Kline D, Arnold WD. Genotype-Phenotype Correlations and Characterization of Medication Use in Inherited Myotonic Disorders. Front Neurol 2020; 11:593. [PMID: 32670189 PMCID: PMC7332828 DOI: 10.3389/fneur.2020.00593] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: Inherited myotonic disorders are genetically heterogeneous and associated with overlapping clinical features of muscle stiffness, weakness, and pain. Data on genotype-phenotype correlations are limited. In this study, clinical features and treatment patterns in genetically characterized myotonic disorders were compared. Methods: A retrospective chart review was completed in patients with genetic variants in CLCN1, SCN4A, DMPK, and CNBP to document clinical signs and symptoms, clinical testing, and antimyotonia medication use. Results: A total of 142 patients (27 CLCN1, 15 SCN4A, 89 DMPK, and 11 CNBP) were reviewed. The frequency of reported symptoms (stiffness, weakness, and pain) and electromyographic spontaneous activity were remarkably similar across genotypes. Most patients were not treated with antimyotonia agents, but those with non-dystrophic disorders were more likely to be on a treatment. Discussion: Among the features reviewed, we did not identify clinical or electrophysiological differences to distinguish CLCN1- and SCN4A-related myotonia. Weakness and pain were more prevalent in non-dystrophic disorders than previously identified. In addition, our results suggest that medical treatments in myotonic disorders may be under-utilized.
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Affiliation(s)
- Alayne P Meyer
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Jennifer Roggenbuck
- Division of Human Genetics, The Ohio State University, Columbus, OH, United States
| | - Samantha LoRusso
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - John Kissel
- Department of Neurology, The Ohio State University, Columbus, OH, United States
| | - Rachel M Smith
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - David Kline
- Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University, Columbus, OH, United States
| | - W David Arnold
- Department of Neurology, The Ohio State University, Columbus, OH, United States
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23
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Molenaar JP, Verhoeven JI, Rodenburg RJ, Kamsteeg EJ, Erasmus CE, Vicart S, Behin A, Bassez G, Magot A, Péréon Y, Brandom BW, Guglielmi V, Vattemi G, Chevessier F, Mathieu J, Franques J, Suetterlin K, Hanna MG, Guyant-Marechal L, Snoeck MM, Roberts ME, Kuntzer T, Fernandez-Torron R, Martínez-Arroyo A, Seeger J, Kusters B, Treves S, van Engelen BG, Eymard B, Voermans NC, Sternberg D. Clinical, morphological and genetic characterization of Brody disease: an international study of 40 patients. Brain 2020; 143:452-466. [PMID: 32040565 PMCID: PMC7009512 DOI: 10.1093/brain/awz410] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/30/2019] [Accepted: 11/16/2019] [Indexed: 11/17/2022] Open
Abstract
Brody disease is an autosomal recessive myopathy characterized by exercise-induced muscle stiffness due to mutations in the ATP2A1 gene. Almost 50 years after the initial case presentation, only 18 patients have been reported and many questions regarding the clinical phenotype and results of ancillary investigations remain unanswered, likely leading to incomplete recognition and consequently under-diagnosis. Additionally, little is known about the natural history of the disorder, genotype-phenotype correlations, and the effects of symptomatic treatment. We studied the largest cohort of Brody disease patients to date (n = 40), consisting of 22 new patients (19 novel mutations) and all 18 previously published patients. This observational study shows that the main feature of Brody disease is an exercise-induced muscle stiffness of the limbs, and often of the eyelids. Onset begins in childhood and there was no or only mild progression of symptoms over time. Four patients had episodes resembling malignant hyperthermia. The key finding at physical examination was delayed relaxation after repetitive contractions. Additionally, no atrophy was seen, muscle strength was generally preserved, and some patients had a remarkable athletic build. Symptomatic treatment was mostly ineffective or produced unacceptable side effects. EMG showed silent contractures in approximately half of the patients and no myotonia. Creatine kinase was normal or mildly elevated, and muscle biopsy showed mild myopathic changes with selective type II atrophy. Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) activity was reduced and western blot analysis showed decreased or absent SERCA1 protein. Based on this cohort, we conclude that Brody disease should be considered in cases of exercise-induced muscle stiffness. When physical examination shows delayed relaxation, and there are no myotonic discharges at electromyography, we recommend direct sequencing of the ATP2A1 gene or next generation sequencing with a myopathy panel. Aside from clinical features, SERCA activity measurement and SERCA1 western blot can assist in proving the pathogenicity of novel ATP2A1 mutations. Finally, patients with Brody disease may be at risk for malignant hyperthermia-like episodes, and therefore appropriate perioperative measures are recommended. This study will help improve understanding and recognition of Brody disease as a distinct myopathy in the broader field of calcium-related myopathies.
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Affiliation(s)
- Joery P Molenaar
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jamie I Verhoeven
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Richard J Rodenburg
- Department of Pediatrics, Translational Metabolic Laboratory, Radboud Center for Mitochondrial Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Erik J Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corrie E Erasmus
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Savine Vicart
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Anthony Behin
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Guillaume Bassez
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Armelle Magot
- CHU Nantes, Centre de Référence Maladies Neuromusculaires AOC, Nantes, France
| | - Yann Péréon
- CHU Nantes, Centre de Référence Maladies Neuromusculaires AOC, Nantes, France
| | - Barbara W Brandom
- Department of Anesthesiology, Children's Hospital, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Valeria Guglielmi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy
| | - Gaetano Vattemi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Clinical Neurology, University of Verona, Verona, Italy
| | | | - Jean Mathieu
- Neuromuscular Clinic, Centre de Réadaptation en Déficience Physique de Jonquière, Jonquière, Québec, Canada
| | - Jérôme Franques
- Centre de référence des maladies neuromusculaires et de la SLA, hôpital La Timone, AP-HM, Aix-Marseille université, avenue Jean-Moulin, Marseille, France
| | - Karen Suetterlin
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | | | - Marc M Snoeck
- Department of Anaesthesiology, Canisius-Wilhelmina Ziekenhuis, Nijmegen, The Netherlands
| | - Mark E Roberts
- Department of Neurology, Salford Royal NHS Foundation Trust, Greater Manchester, UK
| | - Thierry Kuntzer
- Nerve-Muscle Unit, Service of Neurology, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Roberto Fernandez-Torron
- Neuromuscular Area, Biodonostia Health Research Institute, Department of Neurology, University Hospital Donostia, CIBERNED, San Sebastián, Spain
| | | | - Juergen Seeger
- Sozialpädiatrisches Zentrum Frankfurt Mitte, Neuromuskulares Zentrum, Frankfurt, Germany
| | - Benno Kusters
- Department of Pathology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Susan Treves
- Departments of Anesthesia and Biomedicine, Basel University and Basel University Hospital, Basel, Switzerland.,Department of Life Sciences, University of Ferrara, Ferrara, Italy
| | - Baziel G van Engelen
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Bruno Eymard
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Nicol C Voermans
- Department of Neurology, Donders Centre for Medical Neuroscience, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Damien Sternberg
- Assistance Publique-Hôpitaux de Paris, Centre de Référence des Canalopathies Musculaires, Centre de Référence des Maladies Neuromusculaires-Paris Est et Service de Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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24
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Prior DE, Ghosh PS. Clinical Reasoning: A 10-year-old girl with muscle stiffness. Neurology 2020; 95:e773-e778. [PMID: 32554772 DOI: 10.1212/wnl.0000000000010026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Devin E Prior
- From the Department of Neurology (D.E.P.), Lahey Clinic, Burlington; and Department of Neurology (P.S.G.), Boston Children's Hospital, MA
| | - Partha S Ghosh
- From the Department of Neurology (D.E.P.), Lahey Clinic, Burlington; and Department of Neurology (P.S.G.), Boston Children's Hospital, MA.
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Changes of Resurgent Na + Currents in the Na v1.4 Channel Resulting from an SCN4A Mutation Contributing to Sodium Channel Myotonia. Int J Mol Sci 2020; 21:ijms21072593. [PMID: 32276507 PMCID: PMC7177622 DOI: 10.3390/ijms21072593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/30/2020] [Accepted: 04/06/2020] [Indexed: 12/19/2022] Open
Abstract
Myotonia congenita (MC) is a rare disorder characterized by stiffness and weakness of the limb and trunk muscles. Mutations in the SCN4A gene encoding the alpha-subunit of the voltage-gated sodium channel Nav1.4 have been reported to be responsible for sodium channel myotonia (SCM). The Nav1.4 channel is expressed in skeletal muscles, and its related channelopathies affect skeletal muscle excitability, which can manifest as SCM, paramyotonia and periodic paralysis. In this study, the missense mutation p.V445M was identified in two individual families with MC. To determine the functional consequences of having a mutated Nav1.4 channel, whole-cell patch-clamp recording of transfected Chinese hamster ovary cells was performed. Evaluation of the transient Na+ current found that a hyperpolarizing shift occurs at both the activation and inactivation curves with an increase of the window currents in the mutant channels. The Nav1.4 channel's co-expression with the Navβ4 peptide can generate resurgent Na+ currents at repolarization following a depolarization. The magnitude of the resurgent currents is higher in the mutant than in the wild-type (WT) channel. Although the decay kinetics are comparable between the mutant and WT channels, the time to the peak of resurgent Na+ currents in the mutant channel is significantly protracted compared with that in the WT channel. These findings suggest that the p.V445M mutation in the Nav1.4 channel results in an increase of both sustained and resurgent Na+ currents, which may contribute to hyperexcitability with repetitive firing and is likely to facilitate recurrent myotonia in SCM patients.
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Burakgazi AZ. Electrodiagnostic findings in myotonic dystrophy: A study on 12 patients. Neurol Int 2019; 11:8205. [PMID: 31871599 PMCID: PMC6908961 DOI: 10.4081/ni.2019.8205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 11/05/2019] [Indexed: 11/29/2022] Open
Abstract
Myotonic dystrophy (DM) is a complex multisystem disease with specific clinical and electrodiagnostic findings. Myotonia can be seen in the distal and proximal muscle groups in upper and lower limbs. There is no established guideline to demonstrate the sensitivity of muscles in the diagnosis of myotonic dystrophy. The aims of this study are to describe common electrodiagnostic findings in patients with DM; and to assess the electrodiagnostic sensitivity of muscles in the diagnosis of DM. In this retrospective study, patients’ age, sex, nerve conduction study findings including common upper and lower limbs nerve functions, and needle examination findings were collected and analyzed. A descriptive analysis (with percentage) was performed on the data obtained from the charts. NCS analysis showed more than half of patients had normal sensory and motor NCS findings. In 11 over 12 patients, sensory NCSs were within normal limits. Only one patient showed abnormal sensory responses. The most common abnormal NCS findings were decreased amplitude with normal latency and normal conduction velocity. The needle analysis showed distal muscles including first dorsal interosseous, abductor policies brevis, tibialis anterior, medial gastrocnemius and peroneal longus muscles are more sensitive in detecting myotonic discharges than proximal muscles including deltoid, triceps, vastus medialis and vastus lateralis. Our findings showed sensory nerve responses were usually within normal limits. The most common NCS abnormality showed decreased motor nerve amplitudes. The needle test showed myotonic discharges were more prominent in the distal muscles in upper and lower limbs.
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Affiliation(s)
- Ikjae Lee
- From the Departments of Neurology (I.L., K.N.) and Medicine (J.B.W., L.L.W.), University of Alabama at Birmingham, Birmingham
| | - Jeremey B Walker
- From the Departments of Neurology (I.L., K.N.) and Medicine (J.B.W., L.L.W.), University of Alabama at Birmingham, Birmingham
| | - Kenkichi Nozaki
- From the Departments of Neurology (I.L., K.N.) and Medicine (J.B.W., L.L.W.), University of Alabama at Birmingham, Birmingham
| | - Lisa L Willett
- From the Departments of Neurology (I.L., K.N.) and Medicine (J.B.W., L.L.W.), University of Alabama at Birmingham, Birmingham
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Zakia LS, Palumbo MIP, Teixeira RBC, Resende LAL, Soares MP, de Oliveira-Filho JP, Amorim RM, Borges AS. Neuromyotonia in a horse. J Vet Intern Med 2018; 33:287-291. [PMID: 30511761 PMCID: PMC6335518 DOI: 10.1111/jvim.15353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 09/21/2018] [Indexed: 01/04/2023] Open
Abstract
This article describes the clinical and electromyographic findings of neuromyotonia in a 19‐month‐old male crossbred Quarter Horse that presented with stiffness and muscle asymmetry in the hind limbs as well as sacrococcygeal, paravertebral, and gluteal myokymia. An electromyographic study showed spontaneous continuous muscle fiber activity with high‐frequency discharges, fibrillations, positive sharp waves, fasciculation potentials, and complex repetitive discharges. Histological examination of the gluteal muscle showed a mixed neurogenic and myopathic pattern. The findings are consistent with neuromyotonia.
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Affiliation(s)
- Luiza Stachewski Zakia
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine and Animal Sciences, Sao Paulo State University (Unesp), Botucatu, Sao Paulo, Brazil
| | - Mariana Isa Pocci Palumbo
- School of Veterinary Medicine and Animal Sciences, Federal University of Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul, Brazil
| | | | - Luiz Antônio Lima Resende
- Department of Neurology, Psychology and Psychiatry, School of Medicine of Botucatu, Sao Paulo State University (Unesp), Botucatu, Sao Paulo, Brazil
| | | | - José Paes de Oliveira-Filho
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine and Animal Sciences, Sao Paulo State University (Unesp), Botucatu, Sao Paulo, Brazil
| | - Rogério Martins Amorim
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine and Animal Sciences, Sao Paulo State University (Unesp), Botucatu, Sao Paulo, Brazil
| | - Alexandre Secorun Borges
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine and Animal Sciences, Sao Paulo State University (Unesp), Botucatu, Sao Paulo, Brazil
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Abstract
Skeletal muscle channelopathies are rare heterogeneous diseases with marked genotypic and phenotypic variability. These disorders cause lifetime disability and impact quality of life. Despite advances in understanding of the molecular pathology of these disorders, the diverse phenotypic manifestations remain a challenge in diagnosis, therapeutic, genetic counseling, and research planning. Electrodiagnostic testing is useful in directing the diagnosis, but has several limitations: patient discomfort, time consuming, and significant overlap of findings in muscle channelopathies. Although genetic testing is the gold standard in making a definitive diagnosis, a mutation might not be identified in many patients with a well-supported clinical diagnosis of periodic paralysis. In the recent past, there have been landmark clinical trials in non-dystrophic myotonia and periodic paralysis which are encouraging as they demonstrate the ability of robust clinical research consortia to conduct well-controlled trials of rare diseases.
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Affiliation(s)
- Lauren Phillips
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas, 75390, USA
| | - Jaya R Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas, 75390, USA.
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Pešović J, Perić S, Brkušanin M, Brajušković G, Rakočević-Stojanović V, Savić-Pavićević D. Molecular genetic and clinical characterization of myotonic dystrophy type 1 patients carrying variant repeats within DMPK expansions. Neurogenetics 2017; 18:207-218. [DOI: 10.1007/s10048-017-0523-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 09/05/2017] [Indexed: 12/22/2022]
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Skov M, de Paoli FV, Nielsen OB, Pedersen TH. The anti-convulsants lacosamide, lamotrigine, and rufinamide reduce myotonia in isolated human and rat skeletal muscle. Muscle Nerve 2017; 56:136-142. [PMID: 27783415 DOI: 10.1002/mus.25452] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 10/14/2016] [Accepted: 10/19/2016] [Indexed: 11/11/2022]
Abstract
INTRODUCTION In myotonia congenita, loss of ClC-1 Cl- channel function results in skeletal muscle hyperexcitability and myotonia. Anti-myotonic treatment has typically targeted the voltage-gated sodium channel in skeletal muscle (Nav1.4). In this study we explored whether 3 sodium channel-modulating anti-epileptics can reduce myotonia in isolated rat and human muscle. METHODS Dissected muscles were rendered myotonic by ClC-1 channel inhibition. The ability of the drugs to suppress myotonia was then assessed from subclinical to maximal clinical concentrations. Drug synergy was determined using isobole plots. RESULTS All drugs were capable of abolishing myotonia in both rat and human muscles. Lamotrigine and rufinamide completely suppressed myotonia at submaximal clinical concentrations, whereas lacosamide had to be raised above the maximal clinical concentration to suppress myotonia completely. A synergistic effect of lamotrigine and rufinamide was observed. CONCLUSION These findings suggest that lamotrigine and rufinamide could be considered for anti-myotonic treatment in myotonia congenita. Muscle Nerve 56: 136-142, 2017.
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Affiliation(s)
- Martin Skov
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark
| | - Frank V de Paoli
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark.,Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital Skejby, Aarhus, Denmark
| | - Ole B Nielsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark
| | - Thomas H Pedersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark
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Ahmad FMH, Hari Kumar KVS. A trigger-happy soldier with bilateral ptosis and dysphagia. Biomed J 2016; 38:554-5. [PMID: 27013457 PMCID: PMC6138374 DOI: 10.1016/j.bj.2015.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/14/2015] [Indexed: 12/26/2022] Open
Abstract
Muscular dystrophy encompasses a group of disorders characterized by the progressive weakness of the skeletal muscles. These disorders are mostly inherited and have characteristic age and muscle group predilection. Lingual muscle involvement is an unusual feature in patients with the muscular dystrophy and helps in the differential diagnosis. We recently encountered a serving soldier presenting with complaints of bilateral ptosis and dysphagia of 5 years duration. Examination showed bilateral ptosis, percussion myotonia, generalized muscular atrophy including that of tongue muscles, and a characteristic hatchet facies. Investigations revealed elevated creatine kinase and myotonic discharges on electromyography leading to a diagnosis of myotonic dystrophy type 1. Muscular dystrophy has a varied presentation and can pose a diagnostic problem in clinical practice. We present the case to highlight the differential diagnosis of tongue atrophy in patients with muscular dystrophy.
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Affiliation(s)
- F M H Ahmad
- Departments of Neurology and Endocrinology, Command Hospital, Chandimandir, Panchkula, Haryana, India
| | - K V S Hari Kumar
- Departments of Neurology and Endocrinology, Command Hospital, Chandimandir, Panchkula, Haryana, India.
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The Myotonic Plot Thickens: Electrical Myotonia in Antimuscle-Specific Kinase Myasthenia Gravis. Case Rep Neurol Med 2016; 2015:242691. [PMID: 26770848 PMCID: PMC4681818 DOI: 10.1155/2015/242691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 11/22/2015] [Indexed: 11/18/2022] Open
Abstract
Electrical myotonia is known to occur in a number of inherited and acquired disorders including myotonic dystrophies, channelopathies, and metabolic, toxic, and inflammatory myopathies. Yet, electrical myotonia in myasthenia gravis associated with antibodies against muscle-specific tyrosine kinase (MuSK) has not been previously reported. We describe two such patients, both of whom had a typical presentation of proximal muscle weakness with respiratory failure in the context of a significant electrodecrement in repetitive nerve stimulation. In both cases, concentric needle examination revealed electrical myotonia combined with myopathic motor unit morphology and early recruitment. These findings suggest that MuSK myasthenia should be included within the differential diagnosis of disorders with electrical myotonia.
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Araki K, Nakanishi H, Nakamura T, Atsuta N, Yamada S, Hijikata Y, Hashizume A, Suzuki K, Katsuno M, Sobue G. Myotonia-like symptoms in a patient with spinal and bulbar muscular atrophy. Neuromuscul Disord 2015; 25:913-5. [DOI: 10.1016/j.nmd.2015.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 08/11/2015] [Accepted: 08/14/2015] [Indexed: 10/23/2022]
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Tawadros C, Burnett K, Derbyshire LF, Tawadros T, Clarke NW, Betts CD. External urethral sphincter electromyography in asymptomatic women and the influence of the menstrual cycle. BJU Int 2015; 116:423-31. [PMID: 25600712 DOI: 10.1111/bju.13042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate by electromyography (EMG), the presence of complex repetitive discharges (CRDs) and decelerating bursts (DBs) in the striated external urethral sphincter during the menstrual cycle in female volunteers with no urinary symptoms and complete bladder emptying. SUBJECTS AND METHODS Healthy female volunteers aged 20-40 years, with regular menstrual cycles and no urinary symptoms were recruited. Volunteers completed a menstruation chart, urinary symptom questionnaires, pregnancy test, urine dipstick, urinary free flow and post-void ultrasound bladder scan. Exclusion criteria included current pregnancy, use of hormonal medication or contraception, body mass index of >35 kg/m(2) , incomplete voiding and a history of pelvic surgery. Eligible participants underwent an external urethral sphincter EMG, using a needle electrode in the early follicular phase and the mid-luteal phase of their menstrual cycles. Serum oestradiol and progesterone were measured at each EMG test. RESULTS In all, 119 women enquired about the research and following screening, 18 were eligible to enter the study phase. Complete results were obtained in 15 women. In all, 30 EMG tests were undertaken in the 15 asymptomatic women. Sphincter EMG was positive for CRDs and DBs at one or both phases of the menstrual cycle in eight (53%) of the women. Three had CRDs and DBs in both early follicular and mid-luteal phases. Five had normal EMG activity in the early follicular phase and CRDs and DBs in the mid-luteal phase. No woman had abnormal EMG activity in the early follicular phase and normal activity in the luteal phase. There was no relationship between EMG activity and age, parity or serum levels of oestradiol and progesterone. CONCLUSIONS CRDs and DB activity in the external striated urethral sphincter is present in a high proportion of asymptomatic young women. This abnormal EMG activity has been shown for the first time to change during the menstrual cycle in individual women. CRDs and DBs are more commonly found in the luteal phase of the menstrual cycle. The importance of CRDs and DBs in the aetiology of urinary retention in young women remains uncertain. The distribution and or quantity of abnormal EMG activity in the external urethral sphincter may be important. In a woman with urinary retention the finding of CRDs and DBs by needle EMG does not automatically establish Fowler's syndrome as the explanation for the bladder dysfunction. Urethral pressure profilometry may be helpful in establishing a diagnosis. Opiate use and psychological stress should be considered in young women with urinary retention.
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Affiliation(s)
- Cecile Tawadros
- Department of Urology, Salford Royal NHS Foundation Trust, Salford, UK.,Department of Urology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Katherine Burnett
- Department of Urology, Salford Royal NHS Foundation Trust, Salford, UK
| | | | - Thomas Tawadros
- Department of Urology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Noel W Clarke
- Department of Urology, Salford Royal NHS Foundation Trust, Salford, UK.,Department of Urology, Christie Hospitals NHS Foundation Trust, Manchester, UK
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Skov M, De Paoli FV, Lausten J, Nielsen OB, Pedersen TH. Extracellular magnesium and calcium reduce myotonia in isolated ClC-1 chloride channel-inhibited human muscle. Muscle Nerve 2014; 51:65-71. [PMID: 24710922 DOI: 10.1002/mus.24260] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2014] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Experimental myotonia induced in rat muscle by ClC-1 chloride channel-inhibited has been shown to be related inversely to extracellular concentrations of Mg(2+) and Ca(2+) ([Mg(2+) ]o and [Ca(2+) ]o) within physiological ranges. Because this implicates a role for [Mg(2+)]o and [Ca(2+)]o in the variability of symptoms among myotonia congenita patients, we searched for similar effects of [Mg(2+)]o and [Ca(2+)]o on myotonia in human muscle. METHODS Bundles of muscle fibers were isolated from abdominal rectus in patients undergoing abdominal surgery. Myotonia was induced by ClC-1 inhibition using 9-anthracene carboxylic acid (9-AC) and was assessed from integrals of force induced by 5-Hz stimulation for 2 seconds. RESULTS Myotonia disappeared gradually when [Mg(2+)]o or [Ca(2+)]o were elevated throughout their physiological ranges. These effects of [Mg(2+)]o and [Ca(2+)]o were additive and interchangeable. CONCLUSIONS These findings suggest that variations in symptoms in myotonia congenita patients may arise from physiological variations in serum Mg(2+) and Ca(2+).
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Affiliation(s)
- Martin Skov
- Department of Biomedicine, Aarhus University, Aarhus, Denmark, Ole Worms Allé 4, 8000, Aarhus C, Denmark
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Szmidt-Salkowska E, Gawel M, Lusakowska A, Nojszewska M, Lipowska M, Sulek A, Krysa W, Rajkiewicz M, Seroka A, Kaminska AM. Does quantitative EMG differ myotonic dystrophy type 2 and type 1? J Electromyogr Kinesiol 2014; 24:755-61. [DOI: 10.1016/j.jelekin.2014.05.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 04/22/2014] [Accepted: 05/30/2014] [Indexed: 11/30/2022] Open
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Veyckemans F, Scholtes JL. Myotonic dystrophies type 1 and 2: anesthetic care. Paediatr Anaesth 2013; 23:794-803. [PMID: 23384336 DOI: 10.1111/pan.12120] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/22/2012] [Indexed: 01/19/2023]
Abstract
Myotonic dystrophy is classified as one of the myotonic syndromes although myotonia is only a minor characteristic of it. It is, in fact, also a multisystem disease with cardiac, digestive, ocular, and endocrine abnormalities. Two subgroups are currently identified with many similarities: DM1 refers to classic dystrophia myotonica (Steinert disease), while DM2, formerly called proximal myotonic myopathy has a later onset. The congenital form is present only in DM1. The genetic causes of DM1 and 2 are different but end up in a similar way of altering RNAm processing and splicing of other genes. The anesthetic risk is increased in case of DM1 type. This review summarizes current knowledge concerning the pathophysiology and anesthetic management of this disease in children and adults.
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Affiliation(s)
- Francis Veyckemans
- Anesthesiology, Université catholique de Louvain Medical School, Cliniques universitaires St Luc, Brussels, Belgium.
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Skov M, Riisager A, Fraser JA, Nielsen OB, Pedersen TH. Extracellular magnesium and calcium reduce myotonia in ClC-1 inhibited rat muscle. Neuromuscul Disord 2013; 23:489-502. [PMID: 23623567 DOI: 10.1016/j.nmd.2013.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 03/08/2013] [Accepted: 03/13/2013] [Indexed: 11/16/2022]
Abstract
Loss-of-function mutations in the ClC-1 Cl(-) channel trigger skeletal muscle hyperexcitability in myotonia congenita. For reasons that remain unclear, the severity of the myotonic symptoms can vary markedly even among patients with identical ClC-1 mutations, and may become exacerbated during pregnancy and with diuretic treatment. Since both these conditions are associated with hypomagnesemia and hypocalcemia, we explored whether extracellular Mg(2+) and Ca(2+) ([Mg(2+)]o and [Ca(2+)]o) can affect myotonia. Experimental myotonia was induced in isolated rat muscles by ClC-1 inhibition and effects of [Mg(2+)]o or [Ca(2+)]o on myotonic contractions were determined. Both cations dampened myotonia within their physiological concentration ranges. Thus, myotonic contractile activity was 6-fold larger at 0.3 than at 1.2 mM [Mg(2+)]o and 82-fold larger at 0.3 than at 1.27 mM [Ca(2+)]o. In intracellular recordings of action potentials, the threshold for action potential excitation was raised by 4-6 mV when [Mg(2+)]o was elevated from 0.6 to 3 mM, compatible with an increase in the depolarization of the membrane potential necessary to activate the Na(+) channels. Supporting this notion, mathematical simulations showed that myotonia went from appearing with normal Cl(-) channel function to disappearing in the absence of Cl(-) channel function when Na(+) channel activation was depolarized by 6 mV. In conclusion, variation in serum Mg(2+) and Ca(2+) may contribute to phenotypic variation in myotonia congenita patients.
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Affiliation(s)
- Martin Skov
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus C, Denmark
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Lossin C. Nav 1.4 slow-inactivation: is it a player in the warm-up phenomenon of myotonic disorders? Muscle Nerve 2013; 47:483-7. [PMID: 23381896 DOI: 10.1002/mus.23713] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2012] [Indexed: 11/11/2022]
Abstract
Myotonia is a heritable disorder in which patients are unable to willfully relax their muscles. The physiological basis for myotonia lies in well-established deficiencies of skeletal muscle chloride and sodium conductances. What is unclear is how normal muscle function can temporarily return with repeated movement, the so-called "warm-up" phenomenon. Electrophysiological analyses of the skeletal muscle voltage-gated sodium channel Nav 1.4 (gene name SCN4A), a key player in myotonia, have revealed several parallels between the Nav 1.4 biophysical signature, specifically slow-inactivation, and myotonic warm-up, which suggest that Nav 1.4 is critical not only in producing the myotonic reaction, but also in mediating the warm-up.
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Affiliation(s)
- Christoph Lossin
- Department of Neurology, University of California Davis School of Medicine, 4635 Second Avenue, Room 1004A, Sacramento, California 95817, USA
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Borges AS, Barbosa JD, Resende LAL, Mota LSLS, Amorim RM, Carvalho TL, Garcia JF, Oliveira-Filho JP, Oliveira CMC, Souza JES, Winand NJ. Clinical and molecular study of a new form of hereditary myotonia in Murrah water buffalo. Neuromuscul Disord 2013; 23:206-13. [PMID: 23339992 DOI: 10.1016/j.nmd.2012.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 11/04/2012] [Accepted: 11/12/2012] [Indexed: 10/27/2022]
Abstract
Hereditary myotonia caused by mutations in CLCN1 has been previously described in humans, goats, dogs, mice and horses. The goal of this study was to characterize the clinical, morphological and genetic features of hereditary myotonia in Murrah buffalo. Clinical and laboratory evaluations were performed on affected and normal animals. CLCN1 cDNA and the relevant genomic region from normal and affected animals were sequenced. The affected animals exhibited muscle hypertrophy and stiffness. Myotonic discharges were observed during EMG, and dystrophic changes were not present in skeletal muscle biopsies; the last 43 nucleotides of exon-3 of the CLCN1 mRNA were deleted. Cloning of the genomic fragment revealed that the exclusion of this exonic sequence was caused by aberrant splicing, which was associated with the presence of a synonymous SNP in exon-3 (c.396C>T). The mutant allele triggered the efficient use of an ectopic 5' splice donor site located at nucleotides 90-91 of exon-3. The predicted impact of this aberrant splicing event is the alteration of the CLCN1 translational reading frame, which results in the incorporation of 24 unrelated amino acids followed by a premature stop codon.
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Affiliation(s)
- Alexandre S Borges
- Department of Veterinary Clinical Science, College of Veterinary Medicine and Animal Science, Univ Estadual Paulista (UNESP), Botucatu, Brazil.
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Shah DU, Darras BT, Markowitz JA, Jones HR, Kang PB. The spectrum of myotonic and myopathic disorders in a pediatric electromyography laboratory over 12 years. Pediatr Neurol 2012; 47:97-100. [PMID: 22759684 DOI: 10.1016/j.pediatrneurol.2012.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 05/09/2012] [Indexed: 11/25/2022]
Abstract
This study assessed the spectrum of disorders associated with electrophysiologic myotonia in a pediatric electromyography laboratory. Records of 2234 patients observed in the Electromyography Laboratory at Boston Children's Hospital from 2000-2011 were screened retrospectively for electrophysiologic diagnoses of myotonia and myopathy. Based on electromyography, 11 patients manifested myotonic discharges alone, eight exhibited both myotonic discharges and myopathic motor unit potentials, and 54 demonstrated myopathic motor unit potentials alone. The final diagnoses of patients with myotonic discharges alone included myotonia congenita, paramyotonia congenita, congenital myopathy, and Pompe disease (acid maltase deficiency). The diagnoses of patients with both myotonic discharges and myopathic motor unit potentials included congenital myopathy and non-Pompe glycogen storage diseases. Myotonic discharges are rarely observed in a pediatric electromyography laboratory, but constitute useful findings when present. The presence or absence of concurrent myopathic motor unit potentials may help narrow the differential diagnosis further.
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Affiliation(s)
- Disha U Shah
- Electromyography Laboratory, Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Milone M, Mcevoy KM, Sorenson EJ, Daube JR. Myotonia associated with caveolin-3 mutation. Muscle Nerve 2012; 45:897-900. [DOI: 10.1002/mus.23270] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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46
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Burge J, Hanna MG. Muscle Channelopathies. Neuromuscul Disord 2011. [DOI: 10.1002/9781119973331.ch13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Young NP, Daube JR, Sorenson EJ, Milone M. Absent, unrecognized, and minimal myotonic discharges in myotonic dystrophy type 2. Muscle Nerve 2010; 41:758-62. [PMID: 20513102 DOI: 10.1002/mus.21615] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The purpose of this study was to describe the frequency of absent, unrecognized, or minimal myotonic discharges (MDs) in myotonic dystrophy type 2 (DM2). We performed a retrospective review of needle electromyography (EMG) data prior to genetic diagnosis in 49 DM2 patients at the Mayo Clinic. MDs were not reported on first or repeat EMG studies (n = 8) and not found in archived recordings of 4 patients (8%); archived EMG recordings (n = 4) confirmed the absence of MDs (n = 2), including 1 patient with normal insertional activity in all muscles, and misinterpretation of MDs as slow fibrillation potentials (n = 1) and complex repetitive discharge (CRD) activity (n = 1). Eight (16%) patients had minimal classic MDs with diffusely increased insertional activity, including waning-only MDs in all patients in this group with archived EMG recordings (n = 5). Diffuse MDs were found in 33 (67%) patients. Absent or minimal MDs do not exclude DM2. Over-reliance on diffuse MDs in patients who present with myopathy may lead to delay in genetic diagnosis of DM2.
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Affiliation(s)
- Nathan P Young
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
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Affiliation(s)
- Abhijit Das
- Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
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