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Bulea TC, Guth A, Sarkar N, Gravunder A, Hodsdon B, Farrell K, Comis LE, Parks R, Shimellis H, Ndege V, Ho PS, Mankodi A. Simple and economical HandClench Relaxometer device for reliable and sensitive measurement of grip myotonia in myotonic dystrophy. Neuromuscul Disord 2022; 32:321-331. [DOI: 10.1016/j.nmd.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 01/14/2022] [Accepted: 02/09/2022] [Indexed: 10/19/2022]
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2
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Yahagita Y, Shikino K, Ikusaka M. Grip myotonia. BMJ Case Rep 2021; 14:14/5/e240779. [PMID: 33958356 PMCID: PMC8103832 DOI: 10.1136/bcr-2020-240779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
| | - Kiyoshi Shikino
- General Medicine, Chiba University Hospital, Chiba, Chiba, Japan
| | - Masatomi Ikusaka
- General Medicine, Chiba University Hospital, Chiba, Chiba, Japan
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Kronlage C, Grimm A, Romano A, Stahl JH, Martin P, Winter N, Marquetand J. Muscle Ultrasound Shear Wave Elastography as a Non-Invasive Biomarker in Myotonia. Diagnostics (Basel) 2021; 11:diagnostics11020163. [PMID: 33498617 PMCID: PMC7911703 DOI: 10.3390/diagnostics11020163] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/15/2021] [Accepted: 01/21/2021] [Indexed: 12/31/2022] Open
Abstract
Myotonia, i.e., delayed muscle relaxation in certain hereditary muscle disorders, can be assessed quantitatively using different techniques ranging from force measurements to electrodiagnostics. Ultrasound shear wave elastography (SWE) has been proposed as a novel tool in biomechanics and neuromuscular medicine for the non-invasive estimation of muscle elasticity and, indirectly, muscle force. The aim of this study is to provide ‘proof-of-principle’ that SWE allows a quantitative measurement of the duration of delayed muscle relaxation in myotonia in a simple clinical setting. In six myotonic muscle disorder patients and six healthy volunteers, shear wave velocities (SWV) parallel to the fiber orientation in the flexor digitorum superficialis muscle in the forearm were recorded with a temporal resolution of one per second during fist-clenching and subsequent relaxation; the relaxation time to 10% of normalized shear wave velocity (RT0.1) was calculated. Forty-six SWE imaging sequences were acquired, yielding a mean RT0.1 of 7.38 s in myotonic muscle disorder patients, significantly higher than in healthy volunteers (1.36 s), which is comparable to data obtained by mechanical dynamometry. SWV measurements during the baseline relaxation and voluntary contraction phases did not differ significantly between groups. We conclude that SWE is a promising, non-invasive, widely available tool for the quantitative assessment of myotonia to aid in diagnosis and therapeutic monitoring.
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Yoon SH, Baek JH, Leem J. Improved grip myotonia in a patient with myotonic dystrophy type 1 following electroacupuncture therapy: A CARE-compliant case report. Medicine (Baltimore) 2020; 99:e21845. [PMID: 32925721 PMCID: PMC7489697 DOI: 10.1097/md.0000000000021845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
RATIONALE Myotonic dystrophy type 1 (DM1) is an autosomal-dominant disorder associated with a short life expectancy and various symptoms, including grip myotonia. Even though grip myotonia decreases quality of life, activities of daily living (ADLs), and work performance, very few interventions provide symptomatic relief. PATIENT CONCERNS In this case report, we present a patient with DM1 and gradually worsening grip myotonia. A 35-year-old woman developed grip myotonia at age 27. She had no underlying diseases or family history of relevant conditions, including DM1. She was unresponsive to medication for several years. DIAGNOSIS Her symptoms gradually worsened, and she was finally diagnosed with DM1 via genetic, neurologic, and laboratory testing in a tertiary hospital at age 32. She tried several medication therapies; however, she stopped medication at age 34 due a perceived poor response and several adverse events. INTERVENTION At the age of 35, she underwent 29 sessions (10 minutes per session) of electroacupuncture therapy on TE9 acupuncture point with 120 Hz electrical stimulation over 3 months. OUTCOMES After 3 months, relaxation time after maximal voluntary isometric contraction decreased from 59 to 2 seconds with treatment. Her Michigan Hand Outcomes Questionnaire score improved (total score, 66.6-75.9; ADL sub-score, 59.7-73.6; function sub-score, 70-90; satisfaction sub-score, 75-91.7). Her Measure Yourself Medical Outcome Profile 2 score also improved from 4.33 to 2. There were no serious adverse events. LESSONS Electroacupuncture is a potential treatment modality and produced an immediate antimyotonic effect, and cumulative long-term treatment effect, in a patient with DM1 and grip myotonia. Other notable treatment outcomes included improving relaxation time, hand function, ADLs, and overall satisfaction. Electroacupuncture is a potential treatment modality for patients with DM1 and grip myotonia. Further prospective clinical studies are warranted to confirm this hypothesis.
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Affiliation(s)
- Sang-Hoon Yoon
- Chung-Yeon Central Institute
- Chung-Yeon Korean Medicine Hospital, Seo-gu, Gwangju
| | - Jang-Hyun Baek
- Department of Neurology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine
| | - Jungtae Leem
- Chung-Yeon Central Institute
- Research and Development Institute, CY Pharma Co., Gangnam-gu, Seoul, Republic of Korea
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5
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Avila-Smirnow D, Vargas Leal CP, Beytía Reyes MDLA, Cortés Zepeda R, Escobar RG, Kleinsteuber Saa K, Lagos Lucero M, Avaria Benapres MDLA, Padilla Pérez O, Casar Leturia JC, Mellado Sagredo C, Sternberg D. Non-dystrophic myotonia Chilean cohort with predominance of the SCN4A Gly1306Glu variant. Neuromuscul Disord 2020; 30:554-561. [DOI: 10.1016/j.nmd.2020.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 04/03/2020] [Accepted: 04/23/2020] [Indexed: 01/31/2023]
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Zhang Y, Long C, Bassel-Duby R, Olson EN. Myoediting: Toward Prevention of Muscular Dystrophy by Therapeutic Genome Editing. Physiol Rev 2018; 98:1205-1240. [PMID: 29717930 PMCID: PMC6335101 DOI: 10.1152/physrev.00046.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/22/2017] [Accepted: 12/26/2017] [Indexed: 12/22/2022] Open
Abstract
Muscular dystrophies represent a large group of genetic disorders that significantly impair quality of life and often progress to premature death. There is no effective treatment for these debilitating diseases. Most therapies, developed to date, focus on alleviating the symptoms or targeting the secondary effects, while the underlying gene mutation is still present in the human genome. The discovery and application of programmable nucleases for site-specific DNA double-stranded breaks provides a powerful tool for precise genome engineering. In particular, the CRISPR/Cas system has revolutionized the genome editing field and is providing a new path for disease treatment by targeting the disease-causing genetic mutations. In this review, we provide a historical overview of genome-editing technologies, summarize the most recent advances, and discuss potential strategies and challenges for permanently correcting genetic mutations that cause muscular dystrophies.
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Affiliation(s)
- Yu Zhang
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Chengzu Long
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Eric N Olson
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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Wenninger S, Montagnese F, Schoser B. Core Clinical Phenotypes in Myotonic Dystrophies. Front Neurol 2018; 9:303. [PMID: 29770119 PMCID: PMC5941986 DOI: 10.3389/fneur.2018.00303] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/18/2018] [Indexed: 12/22/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) represent the most frequent multisystemic muscular dystrophies in adulthood. They are progressive, autosomal dominant diseases caused by an abnormal expansion of an unstable nucleotide repeat located in the non-coding region of their respective genes DMPK for DM1 and CNBP in DM2. Clinically, these multisystemic disorders are characterized by a high variability of muscular and extramuscular symptoms, often causing a delay in diagnosis. For both subtypes, many symptoms overlap, but some differences allow their clinical distinction. This article highlights the clinical core features of myotonic dystrophies, thus facilitating their early recognition and diagnosis. Particular attention will be given to signs and symptoms of muscular involvement, to issues related to respiratory impairment, and to the multiorgan involvement. This article is part of a Special Issue entitled “Beyond Borders: Myotonic Dystrophies—A European Perception.”
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Affiliation(s)
- Stephan Wenninger
- Friedrich-Baur-Institute, Klinikum der Universität München, Munich, Germany
| | | | - Benedikt Schoser
- Friedrich-Baur-Institute, Klinikum der Universität München, Munich, Germany
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8
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222nd ENMC International Workshop:: Myotonic dystrophy, developing a European consortium for care and therapy, Naarden, The Netherlands, 1-2 July 2016. Neuromuscul Disord 2018; 28:463-469. [PMID: 29550152 DOI: 10.1016/j.nmd.2018.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/05/2018] [Indexed: 01/08/2023]
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9
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Hogrel JY, Ollivier G, Ledoux I, Hébert LJ, Eymard B, Puymirat J, Bassez G. Relationships between grip strength, myotonia, and CTG expansion in myotonic dystrophy type 1. Ann Clin Transl Neurol 2017; 4:921-925. [PMID: 29296622 PMCID: PMC5740258 DOI: 10.1002/acn3.496] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 02/01/2023] Open
Abstract
In myotonic dystrophy type 1, several studies have suggested causal relationships between CTG repeat length and the severity of symptoms, such as weakness or myotonia. We aimed to explore these relationships in a large population of 144 DM1 patients. All patients underwent clinical and functional assessments using a standardized test for grip strength and myotonia assessment. Myotonia was assessed using a fully automatic software based on mathematical modeling of relaxation force curve. CTG repeat length was statistically correlated with both myotonia and grip strength, which are two major primary neuromuscular symptoms of DM1 patients. However, these relationships are not clinically meaningful and not predictive at the individual level.
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Affiliation(s)
| | | | | | | | - Bruno Eymard
- Institut de Myologie GH Pitié-Salpêtrière Paris France
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10
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Abraham A, Breiner A, Barnett C, Bril V, Katzberg HD. Quantitative sonographic assessment of myotonia. Muscle Nerve 2017; 57:146-149. [DOI: 10.1002/mus.25714] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/17/2017] [Accepted: 05/23/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Alon Abraham
- Ellen and Martin Prosserman Centre for Neuromuscular DiseasesDivision of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital200 Elizabeth Street, Room 5EB‐306A, Toronto Ontario CanadaM5G 2C4
| | - Ari Breiner
- Ellen and Martin Prosserman Centre for Neuromuscular DiseasesDivision of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital200 Elizabeth Street, Room 5EB‐306A, Toronto Ontario CanadaM5G 2C4
| | - Carolina Barnett
- Ellen and Martin Prosserman Centre for Neuromuscular DiseasesDivision of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital200 Elizabeth Street, Room 5EB‐306A, Toronto Ontario CanadaM5G 2C4
| | - Vera Bril
- Ellen and Martin Prosserman Centre for Neuromuscular DiseasesDivision of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital200 Elizabeth Street, Room 5EB‐306A, Toronto Ontario CanadaM5G 2C4
| | - Hans D. Katzberg
- Ellen and Martin Prosserman Centre for Neuromuscular DiseasesDivision of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto General Hospital200 Elizabeth Street, Room 5EB‐306A, Toronto Ontario CanadaM5G 2C4
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11
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Portaro S, Russo M, Naro A, Bramanti A, Bramanti P, Rodolico C, Calabrò RS. Advances in assessing myotonia: Can sensor-engineered glove have a role? J Neurol Sci 2017; 375:3-7. [DOI: 10.1016/j.jns.2017.01.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/17/2016] [Accepted: 01/10/2017] [Indexed: 11/24/2022]
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12
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Symonds T, Campbell P, Randall JA. A review of muscle- and performance-based assessment instruments in DM1. Muscle Nerve 2017; 56:78-85. [DOI: 10.1002/mus.25468] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Tara Symonds
- Clinical Outcomes Solutions; Folkestone Kent United Kingdom
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Esposito F, Cè E, Rampichini S, Monti E, Limonta E, Fossati B, Meola G. Electromechanical delays during a fatiguing exercise and recovery in patients with myotonic dystrophy type 1. Eur J Appl Physiol 2017; 117:551-566. [PMID: 28194519 DOI: 10.1007/s00421-017-3558-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/24/2017] [Indexed: 01/08/2023]
Abstract
PURPOSE The partitioning of the electromechanical delay by an electromyographic (EMG), mechanomyographic (MMG) and force combined approach can provide further insight into the electrochemical and mechanical processes involved with skeletal muscle contraction and relaxation. The aim of the study was to monitor by this combined approach the changes in delays' electrochemical and mechanical components throughout a fatiguing task and during recovery in patients with myotonic dystrophy type 1 (DM1), who present at the skeletal muscle level fibres rearrangement, muscle weakness and myotonia, especially in the distal muscles. METHODS After assessing maximum voluntary contraction (MVC), 14 male patients with DM1 and 14 healthy controls (HC) performed a fatiguing exercise at 50% MVC until exhaustion. EMG, MMG, and force signals were recorded from tibialis anterior and vastus lateralis muscles. The electromechanical delay during contraction (DelayTOT) and relaxation (R-DelayTOT) components, EMG and MMG root mean square (RMS) and mean frequency (MF) were calculated off-line. RESULTS The fatiguing exercise duration was similar in both groups. In patients with DM1, delays components were significantly longer compared to HC, especially in the distal muscle during relaxation. Delays components recovered quickly from the fatiguing exercise in HC than in patients with DM1 in both muscles. CONCLUSIONS The alterations in delays observed in DM1 during the fatiguing exercise may indicate that also the lengthening of the electrochemical and mechanical processes during contraction and relaxation could play a role in explaining exercise intolerance in this pathology.
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Affiliation(s)
- Fabio Esposito
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy. .,IRCCS Fondazione don Gnocchi, Centro di Medicina dello Sport, via Capecelatro 66, 20148, Milan, Italy.
| | - Emiliano Cè
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Susanna Rampichini
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Elena Monti
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Eloisa Limonta
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy
| | - Barbara Fossati
- IRCCS Policlinico San Donato, Piazza Malan 2, 20097, San Donato Milanese (MI), Italy
| | - Giovanni Meola
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Via G. Colombo 71, 20133, Milan, Italy.,IRCCS Policlinico San Donato, Piazza Malan 2, 20097, San Donato Milanese (MI), Italy
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14
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Heatwole C, Bode R, Johnson N, Dekdebrun J, Dilek N, Eichinger K, Hilbert JE, Logigian E, Luebbe E, Martens W, McDermott MP, Pandya S, Puwanant A, Rothrock N, Thornton C, Vickrey BG, Victorson D, Moxley RT. Myotonic dystrophy health index: Correlations with clinical tests and patient function. Muscle Nerve 2016; 53:183-90. [PMID: 26044513 PMCID: PMC4979973 DOI: 10.1002/mus.24725] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 05/21/2015] [Accepted: 05/29/2015] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The Myotonic Dystrophy Health Index (MDHI) is a disease-specific patient-reported outcome measure. Here, we examine the associations between the MDHI and other measures of disease burden in a cohort of individuals with myotonic dystrophy type-1 (DM1). METHODS We conducted a cross-sectional study of 70 patients with DM1. We examined the associations between MDHI total and subscale scores and scores from other clinical tests. Participants completed assessments of strength, myotonia, motor and respiratory function, ambulation, and body composition. Participants also provided blood samples, underwent physician evaluations, and completed other patient-reported outcome measures. RESULTS MDHI total and subscale scores were strongly associated with muscle strength, myotonia, motor function, and other clinical measures. CONCLUSIONS Patient-reported health status, as measured by the MDHI, is associated with alternative measures of clinical health. These results support the use of the MDHI as a valid tool to measure disease burden in DM1 patients.
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Affiliation(s)
- Chad Heatwole
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | | | | | - Jeanne Dekdebrun
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Nuran Dilek
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Katy Eichinger
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - James E. Hilbert
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Eric Logigian
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Elizabeth Luebbe
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - William Martens
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Michael P. McDermott
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
- The University of Rochester Medical Center, Department of Biostatistics and Computational Biology, Rochester, NY
| | - Shree Pandya
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Araya Puwanant
- The University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Nan Rothrock
- Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Charles Thornton
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
| | - Barbara G. Vickrey
- David Geffen School of Medicine, UCLA Medical Center, Los Angeles, CA
- Greater Los Angeles VA HealthCare System, Los Angeles, CA
| | - David Victorson
- Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Richard T. Moxley
- The University of Rochester Medical Center, Department of Neurology, Rochester, NY
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Liu Q, Zheng YF, Zhu YP, Ling SQ, Li WR. Clinical, pathological and genetic characteristics of a pedigree with myotonic dystrophy type 1. Exp Ther Med 2015; 10:1931-1936. [PMID: 26640575 DOI: 10.3892/etm.2015.2738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 07/23/2015] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to investigate the clinical, pathological and molecular genetic characteristics of a pedigree with myotonic dystrophy type 1 (DM1). A series of clinical data from a pedigree with DM1 were collected. Muscle biopsy revealed a typical nuclear ingression within numerous muscle fibers following hematoxylin and eosin staining. Genomic DNA was extracted from the venous blood of two patients and the triplet-primed polymerase chain reaction method was performed to amplify the dystrophia myotonic protein kinase (DMPK) gene. The amplified products were subjected to gene sequencing by capillary fluorescence electrophoresis, and a pathogenic mutation in the DMPK gene comprising >50 cytosine-thymine-guanine repeat sequences was found. DM1 includes multi-system damage, as well as skeletal muscle involvement, and can affect the central nervous system, endocrine glands, skin and heart. A skeletal muscle biopsy and genetic testing can confirm the diagnosis and clarify the severity of the disease. In addition, it is necessary to distinguish DM1 from DM2.
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Affiliation(s)
- Qing Liu
- Department of Neurology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, Shanxi 030009, P.R. China
| | - Yu-Fei Zheng
- Department of Neurology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, Shanxi 030009, P.R. China
| | - Yan-Ping Zhu
- Department of Neurology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, Shanxi 030009, P.R. China
| | - Shi-Qing Ling
- Department of Neurology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, Shanxi 030009, P.R. China
| | - Wei-Rong Li
- Department of Neurology, Taiyuan Central Hospital of Shanxi Medical University, Taiyuan, Shanxi 030009, P.R. China
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Toth A, Lovadi E, Komoly S, Schwarcz A, Orsi G, Perlaki G, Bogner P, Sebok A, Kovacs N, Pal E, Janszky J. Cortical involvement during myotonia in myotonic dystrophy: an fMRI study. Acta Neurol Scand 2015; 132:65-72. [PMID: 25630356 DOI: 10.1111/ane.12360] [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] [Accepted: 11/11/2014] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Myotonic dystrophy type 1 (DM1) is a common adulthood muscular dystrophy, characterized by muscle wasting, myotonia, and multisystemic manifestations. The phenomenon of involuntary muscle contraction during myotonia offers a unique possibility of investigating brain motor functions. This study explores cortical involvement during grip myotonia in DM1. MATERIALS AND METHODS Sixteen DM1 patients were enrolled in the study. Eight patients had apparent grip myotonia, while eight patients did not (control subjects). All patients underwent functional MRI grip task examination twice: prior a warm-up procedure (myotonia was elicited in patients with apparent grip myotonia) and after a warm-up procedure (myotonia was attenuated in patients with apparent grip myotonia). No myotonia was elicited during either examination in patients without apparent grip myotonia. Cerebral blood oxygen level-dependent (BOLD) signals were compared both between groups with and without apparent myotonia, and between pre- and post-warm-up sessions. RESULTS Significantly higher BOLD signal was found during myotonia phase in patients with apparent grip myotonia compared to corresponding non-myotonia phase of patients without apparent grip myotonia in the supplementary motor area and in the dorsal anterior cingulate cortex. Significant differences in BOLD signal levels of very similar pattern were detected between prewarm-up session myotonia phase and post-warm-up session myotonia absent phase in the group of patients with apparent grip myotonia. CONCLUSION We showed that myotonia is related to cortical function in high-order motor control areas. This cortical involvement is most likely to represent action of inhibitory circuits intending motor termination.
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Affiliation(s)
- A. Toth
- Department of Neurology; University of Pécs; Pécs Hungary
| | - E. Lovadi
- Department of Neurology; University of Pécs; Pécs Hungary
| | - S. Komoly
- Department of Neurology; University of Pécs; Pécs Hungary
| | - A. Schwarcz
- Department of Neurosurgery; University of Pécs; Pécs Hungary
- MTA-PTE Clinical Neuroscience MR Research Group; Pécs Hungary
| | - G. Orsi
- MTA-PTE Clinical Neuroscience MR Research Group; Pécs Hungary
- Diagnostic Center of Pécs; Pécs Hungary
| | - G. Perlaki
- MTA-PTE Clinical Neuroscience MR Research Group; Pécs Hungary
- Diagnostic Center of Pécs; Pécs Hungary
| | - P. Bogner
- Department of Neurosurgery; University of Pécs; Pécs Hungary
- Diagnostic Center of Pécs; Pécs Hungary
| | - A. Sebok
- Department of Neurology; University of Pécs; Pécs Hungary
| | - N. Kovacs
- Department of Neurology; University of Pécs; Pécs Hungary
- MTA-PTE Clinical Neuroscience MR Research Group; Pécs Hungary
| | - E. Pal
- Department of Neurology; University of Pécs; Pécs Hungary
| | - J. Janszky
- Department of Neurology; University of Pécs; Pécs Hungary
- MTA-PTE Clinical Neuroscience MR Research Group; Pécs Hungary
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Abstract
PURPOSE OF REVIEW Myotonic dystrophies type 1 and type 2 are progressive multisystem genetic disorders with clinical and genetic features in common. Myotonic dystrophy type 1 is the most prevalent muscular dystrophy in adults and has a wide phenotypic spectrum. The average age of death in myotonic dystrophy type 1 is in the fifth decade. In comparison, myotonic dystrophy type 2 tends to cause a milder phenotype with later onset of symptoms and is less common than myotonic dystrophy type 1. Historically, patients with myotonic dystrophy type 1 have not received the medical and social input they need to maximize their quality and quantity of life. This review describes the improved understanding in the molecular and clinical features of myotonic dystrophy type 1 as well as the screening of clinical complications and their management. We will also discuss new potential genetic treatments. RECENT FINDINGS An active approach to screening and management of myotonic dystrophies type 1 and type 2 requires a multidisciplinary medical, rehabilitative and social team. This process will probably improve morbidity and mortality for patients. Genetic treatments have been successfully used in in-vitro and animal models to reverse the physiological, histopathological and transcriptomic features. SUMMARY Molecular therapeutics for myotonic dystrophy will probably bridge the translational gap between bench and bedside in the near future. There will still be a requirement for clinical screening of patients with myotonic dystrophy with proactive and systematic management of complications.
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Heatwole CR, Statland JM, Logigian EL. The diagnosis and treatment of myotonic disorders. Muscle Nerve 2013; 47:632-48. [PMID: 23536309 DOI: 10.1002/mus.23683] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2012] [Indexed: 12/12/2022]
Abstract
Myotonia is a defining clinical symptom and sign common to a relatively small group of muscle diseases, including the myotonic dystrophies and the nondystrophic myotonic disorders. Myotonia can be observed on clinical examination, as can its electrical correlate, myotonic discharges, on electrodiagnostic testing. Research interest in the myotonic disorders continues to expand rapidly, which justifies a review of the scientific bases, clinical manifestations, and numerous therapeutic approaches associated with these disorders. We review the pathomechanisms of myotonia, the clinical features of the dystrophic and nondystrophic myotonic disorders, and the diagnostic approach and treatment options for patients with symptomatic myotonia.
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Affiliation(s)
- Chad R Heatwole
- Department of Neurology, Box 673, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York, New York 14642, USA.
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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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Statland JM, Bundy BN, Wang Y, Trivedi JR, Raja Rayan D, Herbelin L, Donlan M, McLin R, Eichinger KJ, Findlater K, Dewar L, Pandya S, Martens WB, Venance SL, Matthews E, Amato AA, Hanna MG, Griggs RC, Barohn RJ. A quantitative measure of handgrip myotonia in non-dystrophic myotonia. Muscle Nerve 2012; 46:482-9. [PMID: 22987687 DOI: 10.1002/mus.23402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Non-dystrophic myotonia (NDM) is characterized by myotonia without muscle wasting. A standardized quantitative myotonia assessment (QMA) is important for clinical trials. METHODS Myotonia was assessed in 91 individuals enrolled in a natural history study using a commercially available computerized handgrip myometer and automated software. Average peak force and 90% to 5% relaxation times were compared with historical normal controls studied with identical methods. RESULTS Thirty subjects had chloride channel mutations, 31 had sodium channel mutations, 6 had DM2 mutations, and 24 had no identified mutation. Chloride channel mutations were associated with prolonged first handgrip relaxation times and warm-up on subsequent handgrips. Sodium channel mutations were associated with prolonged first handgrip relaxation times and paradoxical myotonia or warm-up, depending on underlying mutations. DM2 subjects had normal relaxation times but decreased peak force. Sample size estimates are provided for clinical trial planning. CONCLUSION QMA is an automated, non-invasive technique for evaluating myotonia in NDM.
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
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Andersen G, Ørngreen MC, Preisler N, Colding-Jørgensen E, Clausen T, Duno M, Jeppesen TD, Vissing J. Muscle phenotype in patients with myotonic dystrophy type 1. Muscle Nerve 2012; 47:409-15. [PMID: 23169601 DOI: 10.1002/mus.23535] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2012] [Indexed: 11/06/2022]
Abstract
INTRODUCTION The pathogenesis of muscle involvement in patients with myotonic dystrophy type 1 (DM1) is not well understood. In this study, we characterized the muscle phenotype in patients with confirmed DM1. METHODS In 38 patients, muscle strength was tested by hand-held dynamometry. Myotonia was evaluated by a handgrip test and by analyzing the decrement of the compound muscle action potential. Muscle biopsies were assessed for morphological changes and Na(+)-K(+) pump content. RESULTS Muscle strength correlated with a decline in Na(+)-K(+) pump content (r = 0.60, P < 0.001) and with CTG expansion. CTG expansion did not correlate with severity of myotonia, proximal histopathological changes, or Na(+)-K(+) pump content. Histopathologically, we found few centrally placed nuclei (range 0.2-6.9%). CONCLUSIONS The main findings of this study are that muscle weakness correlated inversely with CTG expansion and that central nuclei are not a prominent feature of proximal muscles in DM1.
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Affiliation(s)
- Grete Andersen
- Neuromuscular Research Unit, Department of Neurology, 3342, Rigshospitalet Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
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Statland JM, Bundy BN, Wang Y, Rayan DR, Trivedi JR, Sansone VA, Salajegheh MK, Venance SL, Ciafaloni E, Matthews E, Meola G, Herbelin L, Griggs RC, Barohn RJ, Hanna MG. Mexiletine for symptoms and signs of myotonia in nondystrophic myotonia: a randomized controlled trial. JAMA 2012; 308:1357-65. [PMID: 23032552 PMCID: PMC3564227 DOI: 10.1001/jama.2012.12607] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Nondystrophic myotonias (NDMs) are rare diseases caused by mutations in skeletal muscle ion channels. Patients experience delayed muscle relaxation causing functionally limiting stiffness and pain. Mexiletine-induced sodium channel blockade reduced myotonia in small studies; however, as is common in rare diseases, larger studies of safety and efficacy have not previously been considered feasible. OBJECTIVE To determine the effects of mexiletine for symptoms and signs of myotonia in patients with NDMs. DESIGN, SETTING, AND PARTICIPANTS A randomized, double-blind, placebo-controlled 2-period crossover study at 7 neuromuscular referral centers in 4 countries of 59 patients with NDMs conducted between December 23, 2008, and March 30, 2011, as part of the National Institutes of Health-funded Rare Disease Clinical Research Network. INTERVENTION Oral 200-mg mexiletine or placebo capsules 3 times daily for 4 weeks, followed by the opposite intervention for 4 weeks, with 1-week washout in between. MAIN OUTCOME MEASURES Patient-reported severity score of stiffness recorded on an interactive voice response (IVR) diary (scale of 1 = minimal to 9 = worst ever experienced). Secondary end points included IVR-reported changes in pain, weakness, and tiredness; clinical myotonia assessment; quantitative measure of handgrip myotonia; and Individualized Neuromuscular Quality of Life summary quality of life score (INQOL-QOL, percentage of maximal detrimental impact). RESULTS Mexiletine significantly improved patient-reported severity score stiffness on the IVR diary. Because of a statistically significant interaction between treatment and period for this outcome, primary end point is presented by period (period 1 means were 2.53 for mexiletine and 4.21 for placebo; difference, -1.68; 95% CI, -2.66 to -0.706; P < .001; period 2 means were 1.60 for mexiletine and 5.27 for placebo; difference, -3.68; 95% CI, -3.85 to -0.139; P = .04). Mexiletine improved the INQOL-QOL score (mexiletine, 14.0 vs placebo, 16.7; difference, -2.69; 95% CI, -4.07 to -1.30; P < .001) and decreased handgrip myotonia on clinical examination (mexiletine, 0.164 seconds vs placebo, 0.494 seconds; difference, -0.330; 95% CI, -0.633 to -0.142; P < .001). The most common adverse effect was gastrointestinal (9 mexiletine and 1 placebo). Two participants experienced transient cardiac effects that did not require stopping the study (1 in each group). One serious adverse event was determined to be not study related. CONCLUSION In this preliminary study of patients with NDMs, the use of mexiletine compared with placebo resulted in improved patient-reported stiffness over 4 weeks of treatment, despite some concern about the maintenance of blinding. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00832000.
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Affiliation(s)
- Jeffrey M Statland
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Brian N Bundy
- Pediatrics Epidemiology Center, University of South Florida, Tampa, FL
| | - Yunxia Wang
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Dipa Raja Rayan
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Jaya R Trivedi
- Department of Neurology, University of Texas Southwestern, Dallas, TX
| | - Valeria A Sansone
- Department of Neurology, University of Milan, IRCCS Policlinico San Donato, Milan, Italy
| | - Mohammad K Salajegheh
- Department of Neurology, Neuromuscular Division, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Shannon L. Venance
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, ON Canada
| | - Emma Ciafaloni
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
| | - Giovanni Meola
- Department of Neurology, University of Milan, IRCCS Policlinico San Donato, Milan, Italy
| | - Laura Herbelin
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Robert C Griggs
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, UK
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Udd B, Krahe R. The myotonic dystrophies: molecular, clinical, and therapeutic challenges. Lancet Neurol 2012; 11:891-905. [DOI: 10.1016/s1474-4422(12)70204-1] [Citation(s) in RCA: 335] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Fujii K, Iranami H, Hatano Y. Exacerbation of acetazolamide-responsive sodium channel myotonia by uterotonic agents. Int J Obstet Anesth 2011; 20:76-9. [DOI: 10.1016/j.ijoa.2010.07.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 07/13/2010] [Accepted: 07/23/2010] [Indexed: 11/29/2022]
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Abstract
Myotonic dystrophies (dystrophia myotonica, or DM) are inherited disorders characterized by myotonia and progressive muscle degeneration, which are variably associated with a multisystemic phenotype. To date, two types of myotonic dystrophy, type 1 (DM1) and type 2 (DM2), are known to exist; both are autosomal dominant disorders caused by expansion of an untranslated short tandem repeat DNA sequence (CTG)(n) and (CCTG)(n), respectively. These expanded repeats in DM1 and DM2 show different patterns of repeat-size instability. Phenotypes of DM1 and DM2 are similar but there are some important differences, most conspicuously in the severity of the disease (including the presence or absence of the congenital form), muscles primarily affected (distal versus proximal), involved muscle fiber types (type 1 versus type 2 fibers), and some associated multisystemic phenotypes. The pathogenic mechanism of DM1 and DM2 is thought to be mediated by the mutant RNA transcripts containing expanded CUG and CCUG repeats. Strong evidence supports the hypothesis that sequestration of muscle-blind like (MBNL) proteins by these expanded repeats leads to misregulated splicing of many gene transcripts in corroboration with the raised level of CUG-binding protein 1. However, additional mechanisms, such as changes in the chromatin structure involving CTCN-binding site and gene expression dysregulations, are emerging. Although treatment of DM1 and DM2 is currently limited to supportive therapies, new therapeutic approaches based on pathogenic mechanisms may become feasible in the near future.
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Affiliation(s)
- Tetsuo Ashizawa
- Department of Neurology, McKnight Brain Institute, The University of Texas Medical Branch, Galveston, TX, USA.
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Heatwole CR, Eichinger KJ, Friedman DI, Hilbert JE, Jackson CE, Logigian EL, Martens WB, McDermott MP, Pandya SK, Quinn C, Smirnow AM, Thornton CA, Moxley RT. Open-label trial of recombinant human insulin-like growth factor 1/recombinant human insulin-like growth factor binding protein 3 in myotonic dystrophy type 1. ACTA ACUST UNITED AC 2010; 68:37-44. [PMID: 20837825 DOI: 10.1001/archneurol.2010.227] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE To evaluate the safety and tolerability of recombinant human insulin-like growth factor 1 (rhIGF-1) complexed with IGF binding protein 3 (rhIGF-1/rhIGFBP-3) in patients with myotonic dystrophy type 1 (DM1). DESIGN Open-label dose-escalation clinical trial. SETTING University medical center. PARTICIPANTS Fifteen moderately affected ambulatory participants with genetically proven myotonic dystrophy type 1. INTERVENTION Participants received escalating dosages of subcutaneous rhIGF-1/rhIGFBP-3 for 24 weeks followed by a 16-week washout period. MAIN OUTCOME MEASURES Serial assessments of safety, muscle mass, muscle function, and metabolic state were performed. The primary outcome variable was the ability of participants to complete 24 weeks receiving rhIGF-1/ rhIGFBP-3 treatment. RESULTS All participants tolerated rhIGF-1/rhIGFBP-3. There were no significant changes in muscle strength or functional outcomes measures. Lean body muscle mass measured by dual-energy x-ray absorptiometry increased by 1.95 kg (P < .001) after treatment. Participants also experienced a mean reduction in triglyceride levels of 47 mg/dL (P = .002), a mean increase in HDL levels of 5.0 mg/dL (P = .03), a mean reduction in hemoglobin A(1c) levels of 0.15% (P = .03), and a mean increase in testosterone level (in men) of 203 ng/dL (P = .002) while taking rhIGF-1/rhIGFBP-3. Mild reactions at the injection site occurred (9 participants), as did mild transient hypoglycemia (3), lightheadedness (2), and transient papilledema (1). CONCLUSIONS Treatment with rhIGF-1/rhIGFBP-3 was generally well tolerated in patients with myotonic dystrophy type 1. Treatment with rhIGF-1/rhIGFBP-3 was associated with increased lean body mass and improvement in metabolism but not increased muscle strength or function. Larger randomized controlled trials would be needed to further evaluate the efficacy and safety of this medication in patients with neuromuscular disease. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00233519.
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Affiliation(s)
- Chad R Heatwole
- University of Rochester Medical Center, Rochester, NY 14642, USA.
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Logigian EL, Martens WB, Moxley RT, McDermott MP, Dilek N, Wiegner AW, Pearson AT, Barbieri CA, Annis CL, Thornton CA, Moxley RT. Mexiletine is an effective antimyotonia treatment in myotonic dystrophy type 1. Neurology 2010; 74:1441-8. [PMID: 20439846 DOI: 10.1212/wnl.0b013e3181dc1a3a] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE To determine if mexiletine is safe and effective in reducing myotonia in myotonic dystrophy type 1 (DM1). BACKGROUND Myotonia is an early, prominent symptom in DM1 and contributes to decreased dexterity, gait instability, difficulty with speech/swallowing, and muscle pain. A few preliminary trials have suggested that the antiarrhythmic drug mexiletine is useful, symptomatic treatment for nondystrophic myotonic disorders and DM1. METHODS We performed 2 randomized, double-blind, placebo-controlled crossover trials, each involving 20 ambulatory DM1 participants with grip or percussion myotonia on examination. The initial trial compared 150 mg of mexiletine 3 times daily to placebo, and the second trial compared 200 mg of mexiletine 3 times daily to placebo. Treatment periods were 7 weeks in duration separated by a 4- to 8-week washout period. The primary measure of myotonia was time for isometric grip force to relax from 90% to 5% of peak force after a 3-second maximum grip contraction. EKG measurements and adverse events were monitored in both trials. RESULTS There was a significant reduction in grip relaxation time with both 150 and 200 mg dosages of mexiletine. Treatment with mexiletine at either dosage was not associated with any serious adverse events, or with prolongation of the PR or QTc intervals or of QRS duration. Mild adverse events were observed with both placebo and mexiletine treatment. CONCLUSIONS Mexiletine at dosages of 150 and 200 mg 3 times daily is effective, safe, and well-tolerated over 7 weeks as an antimyotonia treatment in DM1. CLASSIFICATION OF EVIDENCE This study provides Class I evidence that mexiletine at dosages of 150 and 200 mg 3 times daily over 7 weeks is well-tolerated and effective in reducing handgrip relaxation time in DM1.
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Affiliation(s)
- E L Logigian
- Department of Neurology, University of Rochester, Rochester, NY, USA.
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Matynia A, Ng CH, Dansithong W, Chiang A, Silva AJ, Reddy S. Muscleblind1, but not Dmpk or Six5, contributes to a complex phenotype of muscular and motivational deficits in mouse models of myotonic dystrophy. PLoS One 2010; 5:e9857. [PMID: 20360842 PMCID: PMC2845609 DOI: 10.1371/journal.pone.0009857] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 01/24/2010] [Indexed: 11/20/2022] Open
Abstract
Assessment of molecular defects that underlie cognitive deficits observed in mendelian disorders provides a unique opportunity to identify key regulators of human cognition. Congenital Myotonic Dystrophy 1 (cDM1), a multi-system disorder is characterized by both cognitive deficits and a spectrum of behavioral abnormalities, which include visuo-spatial memory deficits, anxiety and apathy. Decreased levels of DMPK (Dystrophia Myotonica-protein kinase), SIX5, a transcription factor or MBNL1 (Muscleblind-like 1), an RNA splice regulator have been demonstrated to contribute to distinct features of cDM1. Mouse strains in which either Dmpk, Six5 or Mbnl1 are inactivated were therefore studied to determine the relative contribution of each gene to these cognitive functions. The open field and elevated plus maze tasks were used to examine anxiety, sucrose consumption was used to assess motivation, whereas the water maze and context fear conditioning were used to examine spatial learning and memory. Cognitive and behavioral abnormalities were observed only in Mbnl1 deficient mice, which demonstrate behavior consistent with motivational deficits in the Morris water maze, a complex visuo-spatial task and in the sucrose consumption test for anhedonia. All three models of cDM1 exhibit normal spatial learning and memory. These data identify MBNL1 as a potential regulator of emotional state with decreased MBNL1 levels underlying the motivational deficits observed in cDM1.
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Affiliation(s)
- Anna Matynia
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, Psychology and the Brain Research Institute, Gonda Neuroscience and Genetics Center, University of California Los Angeles, Los Angeles, California, United States of America
| | - Carina Hoi Ng
- Institute for Genetic Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Warunee Dansithong
- Institute for Genetic Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Andy Chiang
- Institute for Genetic Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Alcino J. Silva
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, Psychology and the Brain Research Institute, Gonda Neuroscience and Genetics Center, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sita Reddy
- Institute for Genetic Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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Logigian EL, Twydell P, Dilek N, Martens WB, Quinn C, Wiegner AW, Heatwole CR, Thornton CA, Moxley RT. Evoked myotonia can be "dialed-up" by increasing stimulus train length in myotonic dystrophy type 1. Muscle Nerve 2010; 41:191-6. [PMID: 19750543 DOI: 10.1002/mus.21481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is unknown how evoked myotonia varies with stimulus frequency or train length, or how it compares to voluntary myotonia in myotonic dystrophy type 1 (DM1). First dorsal interosseous (FDI) tetanic contractions evoked by trains of 10-20 ulnar nerve stimuli at 10-50 HZ were recorded in 10 DM1 patients and 10 normals. For comparison, maximum voluntary handgrip contractions were also recorded. An automated computer program placed cursors along the declining (relaxation) phase of the force recordings at 90% and 5% of peak force (PF) and calculated relaxation times (RTs) between these points. For all stimulus frequencies and train lengths, evoked RTs were much shorter, and evoked PFs were much greater in normals than in DM1. In normals, evoked RT was independent of stimulus frequency and train length, while in DM1 RT was longer for train lengths of 20 stimuli (mean: 9 s in DM1; 0.20 in normals) than for 10 stimuli (mean: 3 s in DM1, 0.19 in normals), but it did not change with stimulus frequency. In both groups PF increased greatly as stimulus frequency rose from 10-50 HZ but only slightly as train length rose from 10-20 stimuli. Voluntary handgrip RT (mean: 1.9 s) was less than evoked FDI RT (mean: 9 s). In DM1, evoked RT can be "dialed up" by increasing stimulus train length. Evoked myotonia testing utilizing a stimulus paradigm of at least 20 stimuli at 30-50 HZ may be useful in antimyotonic drug trials, particularly when grip RT is normal or equivocal.
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Affiliation(s)
- Eric L Logigian
- Department of Neurology, University of Rochester Medical Center, Box 673, 601 Elmwood Avenue, Rochester, New York, USA.
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30
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Turner C, Hilton-Jones D. Pharmacological treatment for muscle weakness and wasting in myotonic dystrophy. Hippokratia 2010. [DOI: 10.1002/14651858.cd008377] [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]
Affiliation(s)
- Chris Turner
- National Hospital for Neurology and Neurosurgery; MRC Centre for Neuromuscular Disease; Queen Square London UK WC1N 3BG
| | - David Hilton-Jones
- John Radcliffe Hospital; Department of Clinical Neurology; Oxford UK OX3 9DU
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Matthews E, Fialho D, Tan SV, Venance SL, Cannon SC, Sternberg D, Fontaine B, Amato AA, Barohn RJ, Griggs RC, Hanna MG. The non-dystrophic myotonias: molecular pathogenesis, diagnosis and treatment. ACTA ACUST UNITED AC 2009; 133:9-22. [PMID: 19917643 DOI: 10.1093/brain/awp294] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The non-dystrophic myotonias are an important group of skeletal muscle channelopathies electrophysiologically characterized by altered membrane excitability. Many distinct clinical phenotypes are now recognized and range in severity from severe neonatal myotonia with respiratory compromise through to milder late-onset myotonic muscle stiffness. Specific genetic mutations in the major skeletal muscle voltage gated chloride channel gene and in the voltage gated sodium channel gene are causative in most patients. Recent work has allowed more precise correlations between the genotype and the electrophysiological and clinical phenotype. The majority of patients with myotonia have either a primary or secondary loss of membrane chloride conductance predicted to result in reduction of the resting membrane potential. Causative mutations in the sodium channel gene result in an abnormal gain of sodium channel function that may show marked temperature dependence. Despite significant advances in the clinical, genetic and molecular pathophysiological understanding of these disorders, which we review here, there are important unresolved issues we address: (i) recent work suggests that specialized clinical neurophysiology can identify channel specific patterns and aid genetic diagnosis in many cases however, it is not yet clear if such techniques can be refined to predict the causative gene in all cases or even predict the precise genotype; (ii) although clinical experience indicates these patients can have significant progressive morbidity, the detailed natural history and determinants of morbidity have not been specifically studied in a prospective fashion; (iii) some patients develop myopathy, but its frequency, severity and possible response to treatment remains undetermined, furthermore, the pathophysiogical link between ion channel dysfunction and muscle degeneration is unknown; (iv) there is currently insufficient clinical trial evidence to recommend a standard treatment. Limited data suggest that sodium channel blocking agents have some efficacy. However, establishing the effectiveness of a therapy requires completion of multi-centre randomized controlled trials employing accurate outcome measures including reliable quantitation of myotonia. More specific pharmacological approaches are required and could include those which might preferentially reduce persistent muscle sodium currents or enhance the conductance of mutant chloride channels. Alternative strategies may be directed at preventing premature mutant channel degradation or correcting the mis-targeting of the mutant channels.
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Affiliation(s)
- E Matthews
- MRC Centre for Neuromuscular Diseases, UCL, Institute of Neurology, Queen Square, London, WC1N 3BG, England
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Caramia F, Mainero C, Gragnani F, Tinelli E, Fiorelli M, Ceschin V, Pantano P, Bucci E, Barra V, Bozzao L, Antonini G. Functional MRI changes in the central motor system in myotonic dystrophy type 1. Magn Reson Imaging 2009; 28:226-34. [PMID: 19695817 DOI: 10.1016/j.mri.2009.07.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 07/03/2009] [Accepted: 07/04/2009] [Indexed: 01/18/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic disease involving multiple organ systems including central nervous system (CNS) and muscles. Few studies have focused on the central motor system in DM1, pointing to a subclinical abnormality in the CNS. The aim of our study was to investigate patterns of cerebral activation in DM1 during a motor task using functional MRI (fMRI). Fifteen DM1 patients, aged 20 to 59 years, and 15 controls of comparable age were scanned during a self-paced sequential finger-to-thumb opposition task of their dominant right hand. Functional MRI images were analyzed using SPM99. Patients underwent clinical and genetic assessment; all subjects underwent a conventional MR study. Myotonic dystrophy type 1 patients showed greater activation than controls in bilateral sensorimotor areas and inferior parietal lobules, basal ganglia and thalami, in the ipsilateral premotor area, insula and supplementary motor area (corrected P<.05). Analysis of the interaction between disease and age showed that correlation with age was significantly greater in patients than in controls in bilateral sensorimotor areas and in contralateral parietal areas. Other clinical and MR characteristics did not correlate with fMRI. Functional changes in DM1 may represent compensatory mechanisms such as reorganization and redistribution of functional networks to compensate for ultrastructural and neurochemical changes occurring as part of the accelerated aging process.
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Affiliation(s)
- Francesca Caramia
- Neuroradiologia, I Facoltà di Medicina e Chirurgia, Università di Roma La Sapienza, Viale dell'Università 30, 00185 Rome, Italy.
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Abstract
The lack of a robust quantitative measure of myotonia has been underlined in previous studies. Recent publications have proposed methods to quantify myotonia based on the measurement of force relaxation times during maximal contractions. However, they present several drawbacks mainly due to unstable force, odd peaks or digital noise. A possible solution to this issue consists in fitting the force curve with a convenient regression model. The aim of this study was, therefore, to provide a regression model in order to fit the force relaxation time curve automatically and to provide a robust index for quantitative assessment of myotonia in clinical settings. Force curves were fitted by an asymmetric sigmoidal function. The inverse function was then used to compute various absolute and relative relaxation times automatically. These variables were calculated for 16 controls and 16 patients with myotonic dystrophy type 1 (DM1). All variables were significantly increased in DM1 patients compared to controls. For instance, the relaxation time between 40 and 60% of the initial contraction level was 18.2 (SD: 3.3) ms in controls and 40.1 (SD: 17.7) ms in DM1 patients. All relaxation variables were highly discriminant. Force curve modelling provides an objective and effective quantification of myotonia.
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Affiliation(s)
- J-Y Hogrel
- Institut de Myologie, GH Pitié-Salpêtrière, 75651 Paris Cedex 13, France.
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Hao M, Akrami K, Wei K, De Diego C, Che N, Ku JH, Tidball J, Graves MC, Shieh PB, Chen F. Muscleblind-like 2 (Mbnl2) -deficient mice as a model for myotonic dystrophy. Dev Dyn 2008; 237:403-10. [PMID: 18213585 DOI: 10.1002/dvdy.21428] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Myotonic dystrophy (DM), the most common adult-onset muscular dystrophy, is caused by CTG or CCTG microsatellite repeat expansions. Expanded DM mRNA microsatellite repeats are thought to accumulate in the nucleus, sequester Muscleblind proteins, and interfere with alternative mRNA splicing. Muscleblind2 (Mbnl2) is a member of the family of Muscleblind RNA binding proteins (that also include Mbnl1 and Mbnl3) that are known to bind CTG/CCTG RNA repeats. Recently, it was demonstrated that Mbnl1-deficient mice have characteristic features of human DM, including myotonia and defective chloride channel expression. Here, we demonstrate that Mbnl2-deficient mice also develop myotonia and have skeletal muscle pathology consistent with human DM. We also find defective expression and mRNA splicing of the chloride channel (Clcn1) in skeletal muscle that likely contributes to the myotonia phenotype. Our results support the hypothesis that Muscleblind proteins and specifically MBNL2 contribute to the pathogenesis of human DM.
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Affiliation(s)
- Minqi Hao
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095-1760, USA
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Kikuchi S, Kozuka N, Uchida E, Ninomiya T, Tatsumi H, Takeda H, Tachi N. The Change of Grip Strength in a Patient with Congenital Myotonic Dystrophy Over a 4-year Period. JOURNAL OF THE JAPANESE PHYSICAL THERAPY ASSOCIATION = RIGAKU RYOHO 2008; 11:23-27. [PMID: 25792886 PMCID: PMC4316524 DOI: 10.1298/jjpta.11.23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 01/28/2008] [Indexed: 06/04/2023]
Abstract
Myotonic dystrophy (MyD) is a neuromuscular disease that is autosomal dominant and the most common form of muscular dystrophy affecting adults. The clinical features of MyD include a multisystemic disorder characterized by myotonia, progressive muscle weakness and wasting, cataracts, premature balding and mental retardation. The most severe type of MyD is classified as congenital MyD (CMyD). The muscle weakness in CMyD is very severe, but muscle development can be observed in the period of growth. However, no clinical case of this type has been reported yet. Therefore, we report on a girl with CMyD who had an increase in muscle strength over a four-year period. The girl with CMyD participated in this study from the age of 9 to the age of 12. The measurement of muscle strength was recorded as the maximum score of grip strength with the use of dynamometers. Grip strength was assessed once a year by the same two physical therapists. Grip strength of CMyD for each year was markedly weak when compared with the normal controls, but muscle strength changed within some specific growth areas. The muscle weakness in CMyD was remarkable, but the result showed that specific muscle strength of CMyD in childhood was actually increased.
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Affiliation(s)
- Shin Kikuchi
- Department of Anatomy 1, Sapporo Medical University School of Medicine, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
| | - Naoki Kozuka
- School of Health Sciences, Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
| | - Eiji Uchida
- Department of Human Science, Faculty of Human Studies, Taisho University, 3-20-1 Nishisugamo, Toshima-ku, Tokyo 170-847, Japan
| | - Takafumi Ninomiya
- Department of Anatomy 1, Sapporo Medical University School of Medicine, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
| | - Haruyuki Tatsumi
- Department of Anatomy 1, Sapporo Medical University School of Medicine, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
| | - Hidekatsu Takeda
- School of Health Sciences, Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
| | - Nobutada Tachi
- School of Health Sciences, Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan
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Boërio D, Hogrel JY, Bassez G, Lefaucheur JP. Neuromuscular excitability properties in myotonic dystrophy type 1. Clin Neurophysiol 2007; 118:2375-82. [PMID: 17890147 DOI: 10.1016/j.clinph.2007.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 07/05/2007] [Accepted: 07/28/2007] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To study neuromuscular excitability in patients with dystrophia myotonica type 1 (DM1). METHODS The neuromuscular recovery cycle following motor nerve stimulation was assessed in 16 DM1 patients who had no sign of peripheral neuropathy or diabetes. Compound muscle action potentials were recorded from the adductor digiti minimi muscle to ulnar nerve stimulation at the wrist. Paired pulses were delivered, consisting of a conditioning stimulus of supramaximal intensity, followed by a submaximal test stimulus. Interstimuli intervals (ISIs) ranged between 1 and 8ms. Durations of the absolute and relative refractory periods (ARP, RRP) and percentages of refractoriness and supernormality at ISIs of 2.6 and 7ms, respectively, were computed using a subtraction method. The results obtained in the series of DM1 patients were compared to those obtained in six patients with other forms of myotonia and to normative values established in a series of age-matched healthy subjects. Correlations were made between excitability parameters, the number of cytosine-thymine-guanine (CTG) repeats, and the severity of myotonia, scored clinically. RESULTS Compared to controls, DM1 patients presented prolonged durations of ARP and RRP, increased refractoriness and reduced supernormality. The decrease in refractoriness correlated with both the number of CTG repeats and the severity of myotonia. CONCLUSIONS Changes in the recovery cycle following supramaximal motor nerve stimulation revealed the existence of subtle alterations of neuromuscular excitability in DM1 patients. SIGNIFICANCE Increase in refractoriness together with a reduced supernormality was consistent with a process of membrane depolarization. Such a depolarization may be related to the loss of chloride channels or to alterations in sodium conductance in the motor axon or the muscle fiber.
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Affiliation(s)
- Delphine Boërio
- Service de Physiologie--Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique--Hôpitaux de Paris, Créteil, France
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Moxley RT, Logigian EL, Martens WB, Annis CL, Pandya S, Moxley RT, Barbieri CA, Dilek N, Wiegner AW, Thornton CA. Computerized hand grip myometry reliably measures myotonia and muscle strength in myotonic dystrophy (DM1). Muscle Nerve 2007; 36:320-8. [PMID: 17587223 DOI: 10.1002/mus.20822] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study was to develop a reliable, sensitive, quantitative measure of grip myotonia and strength and to determine whether CTG repeat length is correlated with grip myotonia and with muscle strength in myotonic dystrophy type 1 (DM1). Three maximum voluntary isometric contractions (MVICs) of the finger flexors (i.e., handgrip) were recorded on 2 successive days using a computerized handgrip myometer in 29 genetically confirmed DM1 patients and 17 normals. An automated computer program calculated MVIC peak force (PF) and relaxation times (RTs) along the declining (relaxation) phase of the force recordings at 90%, 75%, 50%, 10%, and 5% of PF. Patients also underwent quantitative strength testing (QST) manual muscle testing (MMT). The patients had longer grip RTs and lower PFs than normals. RT (90% to 5%) was above the normal mean +2.5 SD in 25 (86%) patients. In DM1, prolongation of RT was mainly in the terminal (50% to 5%), rather than the initial (90% to 50%) phase of relaxation. PFs and RTs for each patient were reproducible on consecutive days. RTs were positively correlated with leukocyte CTG repeat length, whereas measures of muscle strength, such as PF, QST, and MMT, were negatively correlated with repeat length. We conclude that computerized handgrip myometry provides a sensitive, reliable measure of myotonia and strength in DM1 and offers a method to assess natural history and response to treatment.
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Affiliation(s)
- Richard T Moxley
- Department of Neurology, University of Rochester Medical Center, Box 673, 601 Elmwood Avenue, Rochester, New York 14642, USA.
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Cleland JC, Logigian EL. Clinical evaluation of membrane excitability in muscle channel disorders: potential applications in clinical trials. Neurotherapeutics 2007; 4:205-15. [PMID: 17395130 DOI: 10.1016/j.nurt.2007.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Muscle channelopathies are inherited disorders that cause paralysis and myotonia. Molecular technology has contributed immeasurably to diagnostic testing, to correlation of genotype with phenotype, and to insight into the pathophysiology of these disorders. In most cases, the diagnosis of muscle channelopathy is still made on clinical grounds, but is supported by ancillary laboratory and electrodiagnostic testing such as serum potassium measurement, exercise testing, repetitive nerve stimulation, needle electromyography, calculation of muscle fiber conduction velocity, or electromyography power spectra. Although provocative glucose or potassium challenges are now infrequently performed, they have contributed greatly to our understanding of the pathophysiology of these disorders, and to our ability to differentiate between periodic paralysis types. Despite considerable progress, ample opportunity remains for future clinical research, particularly in expanding genotype-phenotype correlations and in optimizing electrodiagnostic methods. With respect to diagnostic testing, there is a need for accurate, efficient, and cost-effective bedside testing, given the substantial proportion (as high as 20%) of genetically undefined cases. Even in genetically defined cases, minimal clinical expressivity due to incomplete penetrance poses a significant challenge to currently available nonmolecular testing.
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Affiliation(s)
- James C Cleland
- University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
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Trip J, Faber C, Ginjaar H, van Engelen B, Drost G. Warm-up phenomenon in myotonia associated with the V445M sodium channel mutation. J Neurol 2007; 254:257-8. [PMID: 17334961 PMCID: PMC1915614 DOI: 10.1007/s00415-006-0353-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2006] [Accepted: 07/11/2006] [Indexed: 11/22/2022]
Affiliation(s)
- J. Trip
- Dept. of Neurology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands
| | - C.G. Faber
- Dept. of Neurology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands
| | - H.B. Ginjaar
- Dept. of Human and Clinical Genetics, University Medical Centre Leiden, Leiden, The Netherlands
| | - B.G.M. van Engelen
- Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, The Netherlands
| | - G. Drost
- Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, The Netherlands
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Abstract
BACKGROUND Abnormal delayed relaxation of skeletal muscles, known as myotonia, can cause disability in myotonic disorders. Sodium channel blockers, tricyclic antidepressive drugs, benzodiazepines, calcium-antagonists, taurine and prednisone may be of use in reducing myotonia. OBJECTIVES To consider the evidence from randomised controlled trials on the efficacy and tolerability of drug treatment in patients with clinical myotonia due to a myotonic disorder. SEARCH STRATEGY We searched the Cochrane Neuromuscular Disease Group trials register (April 2004), MEDLINE (January 1966 to December 2003) and EMBASE (January 1980 to December 2003). Grey literature was handsearched and reference lists of identified studies and reviews were examined. Authors, disease experts and manufacturers of anti-myotonic drugs were contacted. SELECTION CRITERIA We considered all (quasi) randomised trials of participants with myotonia treated with any drug treatment versus no therapy, placebo or any other active drug treatment. The primary outcome measure was:reduced clinical myotonia using two categories: (1) no residual myotonia or improvement of myotonia or (2) No change or worsening of myotonia. Secondary outcome measures were:(1) clinical relaxation time; (2) electromyographic relaxation time; (3) stair test; (4) presence of percussion myotonia; and (5) proportion of adverse events. DATA COLLECTION AND ANALYSIS Two authors extracted the data independently onto standardised extraction forms and disagreements were resolved by discussion. MAIN RESULTS Nine randomised controlled trials were found comparing active drug treatment versus placebo or another active drug treatment in patients with myotonia due to a myotonic disorder. Included trials were double-blind or single-blind crossover studies involving a total of 137 patients of which 109 had myotonic dystrophy type 1 and 28 had myotonia congenita. The studies were of poor quality. Therefore, we were not able to analyse the results of all identified studies. Two small crossover studies without a washout period demonstrated a significant effect of imipramine and taurine in myotonic dystrophy. One small crossover study with a washout period demonstrated a significant effect of clomipramine in myotonic dystrophy. Meta-analysis was not possible. AUTHORS' CONCLUSIONS Due to insufficient good quality data and lack of randomised studies, it is impossible to determine whether drug treatment is safe and effective in the treatment of myotonia. Small single studies give an indication that clomipramine and imipramine have a short-term beneficial effect and that taurine has a long-term beneficial effect on myotonia. Larger, well-designed randomised controlled trials are needed to assess the efficacy and tolerability of drug treatment for myotonia.
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Affiliation(s)
- J Trip
- Academisch Ziekenhuis Maastricht (AZM), Department of Neurology, P. Debyelaan 25 Postbus5800, Maastricht, Limburg, Netherlands, 6202 AZ.
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