Статті в журналах: "Myotonia; Muscle"

1

Bretag, Allan H. "Myotonic diseases since Asmus Julius Thomas Thomsen (1815–1896) and Peter Emil Becker (1908–2000)." Proceedings of the Royal Society of Victoria 127, no. 1 (2015): 59. http://dx.doi.org/10.1071/rs15005.

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Julius Thomsen first published his account of myotonia (an unusual muscle stiffness disorder) in himself and his family in 1876. By November 1971, Peter Becker was already famous for his eponymous Becker muscular dystrophy when he came to the Second International Congress on Muscle Diseases, in Perth. There, he presented an extensive study of myotonia, recognising a recessively inherited disease (now known as Becker’s recessive generalised myotonia), distinct from Thomsen’s myotonia congenita and clearly distinguishable from Steinert’s myotonic dystrophy, both dominantly inherited. Peter Becker, Shirley Bryant, Reinhardt Rüdel and Allan Bretag all met in Perth, with mutual interests in myotonia. They subsequently maintained contact while Bretag undertook research in Germany in 1972–1973 and 1977. Later, in 1978, Bretag worked with Bryant’s myotonic goats in Cincinnati. His research on Thomsen’s and Becker’s myotonias has since progressed to confirmation of Bryant’s chloride hypothesis through a molecular genetic study of the muscle chloride channel, CLC -1. This has culminated in several collaborative papers with German colleagues and, finally, in a mechanistic description of how the CLC -1 channel is gated.

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2

Fanning, Lorna, and Mary MacDermott. "Effect of Temperature Reduction on Myotonia in Rat Skeletal Muscles in vitro." Clinical Science 92, no. 6 (June 1, 1997): 587–92. http://dx.doi.org/10.1042/cs0920587.

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1. The objective of the study was to determine the effect of temperature reduction on the response of rat skeletal muscles to myotonia-inducing agents. 2. A model myotonia was induced in the muscles in vitro, using either the chloride channel blocker anthracene-9-carboxylic acid or chloride-free Krebs solution. This model is similar in its characteristics to the myotonia which occurs in autosomal recessive generalized myotonia congenita in humans. 3. Isometric twitch contractions were recorded in the muscles in Krebs solution before and after the addition of the myotonia-inducing agent. The presence of myotonia was confirmed when the half-relaxation time of the twitch contraction after the addition of the agent was significantly greater than that before its addition. 4. Recordings were made at 37°C, 30°C, 25°C and 15°C. Myotonia developed at 37°C, 30°C and 25°C, but not at 15°C, indicating that at a temperature between 25°C and 15°C, anthracene-9-carboxylic acid-induced myotonia failed to develop. This supports the results obtained in humans suffering from myotonia congenita where myotonic contractions in the adductor pollicis muscle disappeared when the muscle temperature was cooled to 20°C. 5. The myotonia which developed at 37°C could be significantly reduced by exposure to 1 × 10−4 mol/l ouabain or by elevation of the K+ concentration of the Krebs solution to 7.5 mmol/l. 6. Measurements made using microelectrodes showed that the conditions under which myotonia either did not develop or was significantly reduced, i.e. a temperature of 15°C, exposure to 7.5 mmol/l K+ at 37°C or exposure to 1 × 10−4 mol/l ouabain at 37°C, were each associated with membrane depolarization. The results are discussed in terms of a possible role for depolarization in preventing/reducing the myotonic response.

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3

Лихачев, С. А., А. В. Астапенко, И. П. Марьенко, Т. В. Корбут, and Е. С. Степанова. "Dystrophic Myotonia of Rossolimo – Steinert – Kurshman, Sporadic Case. Clinical Observation." Неврология и нейрохирургия. Восточная Европа, no. 1 (April 29, 2020): 120–26. http://dx.doi.org/10.34883/pi.2020.10.1.050.

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Дистрофическая миотония это генетически детерминированное нервно-мышечное заболевание, относящееся к каналопатиям (заболеваниям, связанным с патологией ионных каналов мембран скелетных мышечных волокон). Классическими признаками миотонии являются миотонические феномены, характеризующиеся замедленным расслаблением скелетных мышц после произвольного сокращения или электрической стимуляции и миотоническими разрядами, выявляемые при клиническом обследовании и игольчатой электромиографии соответственно. Типичным представителем является миотоническая дистрофия (или дистрофическая миотония), описанная в начале прошлого века несколькими авторами и получившая название болезни Россолимо Штейнерта Куршмана. Данная нозологическая единица является самым распространенным заболеванием из разряда миотоний и самой частой формой мышечной дистрофии у взрослых людей. Миотония может вовлекать все группы мышц. Однако характер поражения мышц может варьировать в зависимости от конкретного заболевания. В статье описаны этиология, патогенез, формы, диагностика и основные принципы лечения. Описан клинический случай. Dystrophic myotonia is a genetically determined neuromuscular disease related to canalopathies (diseases associated with the pathology of the ion channels of the skeletal muscle fiber membranes). Classic signs of myotonia are myotonic phenomena characterized by delayed relaxation of skeletal muscles after arbitrary contraction or electrical stimulation and myotonic discharges detected during clinical examination and needle electromyography, respectively. A typical representative is myotonic dystrophy (or dystrophic myotonia), described at the beginning of the last century by several authors and called Rossolimo-Steinert-Kurschmann disease. This nosological unit is the most common disease of the category of myotonia and the most common form of muscular dystrophy in adults. Myotonia can involve all muscle groups. However, the nature of muscle damage may vary depending on the specific disease. The article describes the etiology, pathogenesis, forms, diagnosis, and basic principles of treatment. A clinical case is described.

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4

Nikitin, S. S., V. N. Grigoryeva, K. A. Mashkovich, O. L. Mironovich, N. V. Ryadninskaya, and A. V. Polyakov. "Spinal and bulbar muscular atrophy with pseudomyotonia phenomena: a clinical case report." Neuromuscular Diseases 9, no. 4 (January 10, 2020): 51–56. http://dx.doi.org/10.17650/2222-8721-2019-9-4-51-56.

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A clinical description of a 28-year-old man with spinal and bulbar muscular atrophy diagnosed on the basis of the CAG-trinucleotide expansion in the gene coding androgen receptor is presented. He exhibited skeletal muscles and tongue fasciculations, gynecomastia, increased serum testosterone and creatine kinase levels. The peculiarities of the case were the gynecomastia under the age of 7, development of fasciculations at the age of 11 and appearance of hard muscle stiffness with delayed muscle relaxation after voluntary contraction at the age of 15, which resembled typical myotonia. Electromyography showed few signs of mild without myotonic discharge, contrasting with giant motor unit potentials and reduced recruitment. The cause of myotonia-like symptom without myotonic discharge as a feature of skeletal muscles disorder is discussed with the modern view of spinal and bulbar muscular atrophy as a multisystem genetic pathology.

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5

Magnussen, Marcus, Ioannis Karakis, and Taylor B. Harrison. "The Myotonic Plot Thickens: Electrical Myotonia in Antimuscle-Specific Kinase Myasthenia Gravis." Case Reports in Neurological Medicine 2015 (2015): 1–4. http://dx.doi.org/10.1155/2015/242691.

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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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6

Ricker, K. "The expanding clinical and genetic spectrum of the myotonic dystrophies." Neurology Bulletin XXXIII, no. 1-2 (May 15, 2001): 115–16. http://dx.doi.org/10.17816/nb79796.

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7

Bandschapp, Oliver, Hans F. Ginz, Charles L. Soule, Thierry Girard, Albert Urwyler, and Paul A. Iaizzo. "In Vitro Effects of Propofol and Volatile Agents on Pharmacologically Induced Chloride Channel Myotonia." Anesthesiology 111, no. 3 (September 1, 2009): 584–90. http://dx.doi.org/10.1097/aln.0b013e3181b05f23.

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Background Anesthetic choice for patients with chloride channel myotonia remains under debate. The authors have, therefore, investigated the in vitro effects of various anesthetic agents on pharmacologically induced chloride channel myotonia. Methods Functionally viable (> 10 mN force generation) rectus abdominis muscle preparations obtained from normal swine were investigated using in vitro muscle contracture test baths. During continuous 0.1-Hz supramaximal electrical stimulation, the chloride channel blocker 9-anthracenecarboxylic acid (64 microM) was added before the addition of propofol or one of three volatile anesthetics. The concentration of propofol in either Intralipid (n = 11) or dimethyl sulfoxide (n = 10) was doubled every 10 min (from 4-512 microM). The concentration of halothane (n = 8), isoflurane (n = 8), and sevoflurane (n = 8) was doubled from 0.25 vol% up to the maximum dose according to calibrated vaporizers. Control muscle bundles were either untreated (n = 30) or exposed to 9-anthracenecarboxylic acid (n = 19). Results The myotonic reactions induced by 9-anthracenecarboxylic acid were reversed by high-dose (> 64 microM) propofol (P < 0.01). Halothane, isoflurane, or sevoflurane each enhanced the myotonic reactions at 5.4 (P < 0.001), 0.21 (P < 0.01), and 0.5 minimum alveolar concentrations (P < 0.05), respectively. Conclusions The authors' in vitro data imply that propofol administration for general anesthesia may be better suited for patients with chloride channel myotonia versus volatile anesthetics. In isolated swine skeletal muscle bundles, propofol elicited a reversal of 9-anthracenecarboxylic acid-induced chloride channel myotonia, whereas volatile anesthetics further increased the associated myotonic reactions.

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8

Kronlage, Cornelius, Alexander Grimm, Alyssa Romano, Jan-Hendrik Stahl, Pascal Martin, Natalie Winter, and Justus Marquetand. "Muscle Ultrasound Shear Wave Elastography as a Non-Invasive Biomarker in Myotonia." Diagnostics 11, no. 2 (January 23, 2021): 163. http://dx.doi.org/10.3390/diagnostics11020163.

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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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9

Karras, Georgios, Evangelia Nikouli, and Bulent Kiamiloglou. "Laparoscopic cholecystectomy under total intravenous anaesthesia in a patient with myotonic dystrophy type 1 (Steinert’s disease) – a case report." Folia Medica 64, no. 2 (April 30, 2022): 333–36. http://dx.doi.org/10.3897/folmed.64.e59905.

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Myotonic dystrophy type 1 or Steinert’s disease is an autosomal dominant multisystem disease which is characterized by consistent contracture of muscle following stimulation (myotonia). Hypothermia, shivering, mechanical or electric stimulation during surgery can precipitate episodes of myotonia which may complicate the course of anaesthesia. The present case report focuses on successful strategies for providing general anaesthesia for laparoscopic cholecystectomy in a patient affected by this genetic disorder, at a hospital which does not have the facility for postoperative ventilation.

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10

Lueck, John D., Ami Mankodi, Maurice S. Swanson, Charles A. Thornton, and Robert T. Dirksen. "Muscle Chloride Channel Dysfunction in Two Mouse Models of Myotonic Dystrophy." Journal of General Physiology 129, no. 1 (December 11, 2006): 79–94. http://dx.doi.org/10.1085/jgp.200609635.

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Muscle degeneration and myotonia are clinical hallmarks of myotonic dystrophy type 1 (DM1), a multisystemic disorder caused by a CTG repeat expansion in the 3′ untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. Transgenic mice engineered to express mRNA with expanded (CUG)250 repeats (HSALR mice) exhibit prominent myotonia and altered splicing of muscle chloride channel gene (Clcn1) transcripts. We used whole-cell patch clamp recordings and nonstationary noise analysis to compare and biophysically characterize the magnitude, kinetics, voltage dependence, and single channel properties of the skeletal muscle chloride channel (ClC-1) in individual flexor digitorum brevis (FDB) muscle fibers isolated from 1–3-wk-old wild-type and HSALR mice. The results indicate that peak ClC-1 current density at −140 mV is reduced >70% (−48.5 ± 3.6 and −14.0 ± 1.6 pA/pF, respectively) and the kinetics of channel deactivation increased in FDB fibers obtained from 18–20- d-old HSALR mice. Nonstationary noise analysis revealed that the reduction in ClC-1 current density in HSALR FDB fibers results from a large reduction in ClC-1 channel density (170 ± 21 and 58 ± 11 channels/pF in control and HSALR fibers, respectively) and a modest decrease in maximal channel open probability(0.91 ± 0.01 and 0.75 ± 0.03, respectively). Qualitatively similar results were observed for ClC-1 channel activity in knockout mice for muscleblind-like 1 (Mbnl1ΔE3/ΔE3), a second murine model of DM1 that exhibits prominent myotonia and altered Clcn1 splicing (Kanadia et al., 2003). These results support a molecular mechanism for myotonia in DM1 in which a reduction in both the number of functional sarcolemmal ClC-1 and maximal channel open probability, as well as an acceleration in the kinetics of channel deactivation, results from CUG repeat–containing mRNA molecules sequestering Mbnl1 proteins required for proper CLCN1 pre-mRNA splicing and chloride channel function.

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11

Vita, Gary M., Antonel Olckers, Anne E. Jedlicka, Alfred L. George, Terry Heiman-Patterson, Henry Rosenberg, Jeffrey E. Fletcher та Roy C. Levitt. "Masseter Muscle Rigidity Associated with Glycine1306-to- Alanine Mutation in the Adult Muscle Sodium Channel α-Subunit Gene". Anesthesiology 82, № 5 (1 травня 1995): 1097–103. http://dx.doi.org/10.1097/00000542-199505000-00002.

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Background Succinylcholine-induced masseter muscle rigidity (MMR) is a potentially life-threatening complication of anesthesia and is closely correlated with the heterogeneous disorder malignant hyperthermia (MH) susceptibility. MMR also is identified with a variety of neuromuscular disorders, including the myotonias, that are associated with abnormal in vitro contracture test (IVCT) results. Recently, mutations in the adult skeletal muscle sodium channel alpha-subunit gene (SCN4A) have been shown to cause generalized nondystrophic myotonias, some of which are associated with mild nonspecific symptoms. The purpose of the current investigation was to begin to evaluate the molecular genetic relationship between known mutations in the SCN4A gene, MMR, and the results of the IVCT used to diagnose MH-susceptibility. Methods A single extended pedigree of 16 individuals was ascertained through a proband who experienced MMR and whole-body rigidity after succinylcholine administration. Subsequently, four individuals were shown to have a mild form of myotonia on clinical and laboratory examination. IVCT was carried out according to standardized protocols. Mutations in the SCN4A gene were sought in exons 22 and 24 using single-strand conformational analyses. Variability in the SCN4A gene sequence was confirmed by direct DNA sequence analyses. Results Four individuals with myotonia were shown to carry a guanine-to-cytosine mutation at nucleotide position 3917 of the reported SCN4A sequence. This DNA mutation was coinherited with MMR and an abnormal IVCT result in this family. Previous studies have demonstrated that the glycine1306-to-alanine substitution is associated with a mild clinical syndrome referred to as myotonia fluctuans. Conclusions The current report provides direct evidence that succinylcholine-induced MMR, whole-body rigidity, and an abnormal IVCT result are associated with a mutation in the SCN4A gene.

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Palmio, Johanna, Satu Sandell, Michael G. Hanna, Roope Männikkö, Sini Penttilä, and Bjarne Udd. "Predominantly myalgic phenotype caused by the c.3466G>A p.A1156T mutation in SCN4A gene." Neurology 88, no. 16 (March 22, 2017): 1520–27. http://dx.doi.org/10.1212/wnl.0000000000003846.

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Objective:To characterize the clinical phenotype in patients with p.A1156T sodium channel mutation.Methods:Twenty-nine Finnish patients identified with the c.3466G>A p.A1156T mutation in the SCN4A gene were extensively examined. In a subsequent study, 63 patients with similar myalgic phenotype and with negative results in myotonic dystrophy type 2 genetic screening (DM2-neg group) and 93 patients diagnosed with fibromyalgia were screened for the mutation. Functional consequences of the p.A1156T mutation were studied in HEK293 cells with whole-cell patch clamp.Results:The main clinical manifestation in p.A1156T patients was not myotonia or periodic paralysis but exercise- and cold-induced muscle cramps, muscle stiffness, and myalgia. EMG myotonic discharges were detected in most but not all. Electrophysiologic compound muscle action potentials exercise test showed variable results. The p.A1156T mutation was identified in one patient in the DM2-neg group but not in the fibromyalgia group, making a total of 30 patients so far identified. Functional studies of the p.A1156T mutation showed mild attenuation of channel fast inactivation.Conclusions:The unspecific symptoms of myalgia stiffness and exercise intolerance without clinical myotonia or periodic paralysis in p.A1156T patients make the diagnosis challenging. The symptoms of milder SCN4A mutations may be confused with other similar myalgic syndromes, including fibromyalgia and myotonic dystrophy type 2.

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Reifer, H., and E. Sobel. "Contrasts in clinical presentation and genetic transmission of myotonic dystrophy." Journal of the American Podiatric Medical Association 88, no. 7 (July 1, 1998): 313–22. http://dx.doi.org/10.7547/87507315-88-7-313.

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Myotonic dystrophy, the most common inherited neuromuscular disease, is an autosomal dominant muscular dystrophy characterized by myotonia and distal muscle weakness. It is caused by an increase in the number of cytosine-thymine-guanine (CTG) nucleotide repeats present on the long arm of chromosome 19. Two patients were evaluated, one with classic adult-onset myotonic dystrophy and the other with congenital myotonic dystrophy. Contrasts in the clinical features and genetic transmission of this disease and clinical management are reviewed.

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Behrens, M. I., and C. Vergara. "Increase of apamin receptors in skeletal muscle induced by colchicine: possible role in myotonia." American Journal of Physiology-Cell Physiology 263, no. 4 (October 1, 1992): C794—C802. http://dx.doi.org/10.1152/ajpcell.1992.263.4.c794.

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We have shown an increase of apamin receptors in rat skeletal muscle membranes following the application of colchicine to the sciatic nerve. 125I-apamin binding to partially purified membrane fractions was observed since day 4, reached a maximum around days 6-15, and was negligible at day 35 after the application of colchicine. Control muscles (nerves treated with buffer solution) showed low binding values (11 fmol/mg protein). Maximal 125I-apamin binding values to partially purified muscle membranes of colchicine-treated rats (42 fmol/mg protein) were lower than those obtained in denervated muscle (95 fmol/mg protein). The affinity binding constant values were 37 (colchicine) and 95 pM (denervation). No signs of muscle denervation were observed on histological examination of the nerve submitted to colchicine treatment nor in the muscles innervated by it. Muscle tension developed by indirect stimulation was the same as in controls. We here show also that partially purified membranes of normal untreated muscles have measurable amounts of 125I-apamin binding (13 fmol/mg protein), similar to those obtained in control muscles. Electromyographic recordings of the muscles after colchicine treatment of the nerve showed abnormal repetitive electrical discharges, similar to myotonic discharges, that were present with a similar temporal course as the increase in apamin receptors. The myotonic-like discharges were suppressed by the topical application of apamin to the muscle, whereas the toxin had no effect on anthracene-9-carbolytic acid-induced myotonia. Our results suggest that a neurotrophic factor that travels by axonal flow is involved in the regulation of the expression of apamin receptors in skeletal muscle membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

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Chu, Kon, Jin-Whan Cho, Eun-Chol Song, and Beom S. Jeon. "A Patient with Proximal Myotonic Myopathy and Parkinsonism." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 29, no. 2 (May 2002): 188–90. http://dx.doi.org/10.1017/s0317167100121006.

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Abstract:Introduction:There are two case reports of patients who had proximal myotonic myopathy (PROMM) / myotonic dystrophy (DM) Type 1 and parkinsonism. The combination of myotonic myopathy and parkinsonism is so rare that it may appear to be just a coincidence. However, previous neuropathological examinations of patients who had myotonic dystrophy showed that there were intracytoplasmic inclusion bodies in the nigra and striatum, which raises the possibility that myotonic myopathy may be associated with parkinsonism. In this report we describe a patient with PROMM and a clinically definite parkinsonism to highlight this possibility.Case Report:A 65-year-old man developed proximal muscle weakness, myotonia and atrophy around the age of 55 and was diagnosed as having PROMM at the age of 62. Needle electromyography and muscle biopsy supported the diagnosis. A gene study of the DM Type 1 showed a normal CTG repeat length. At age 63, he developed rest tremor, bradykinesia, hypomimia, stooped posture, and gait disturbance. The postural instability worsened rapidly. The tremor and rigidity were much worse in his right side, where myotonia was more severe. Levodopa therapy was only partially effective.Conclusion:This is a case report of a patient with PROMM that shows an association with a rapidly progressive form of parkinsonism. We suggest that this may be a novel form of a neurodegenerative disorder, which we name ‘Parkinsonism- Myotonic Myopathy-Complex’.

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Hasan, Syed Shakir. "Anesthetic management of a patient with myotonia congenita." Anaesthesia, Pain & Intensive Care 25, no. 6 (December 19, 2021): 816–18. http://dx.doi.org/10.35975/apic.v25i6.1712.

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Myotonia congenita is also known as Becker’s disease. It is a genetic disorder in which skeletal muscles are unable to relax quickly after voluntary movements. Symptoms may vary from person to person and may include muscle stiffness and weakness initiated by movement after rest. Myotonia congenita was first described by Thomsen in 1876 as a disorder of skeletal muscles. Patients suffer from muscle contractility and fatigue which occurs as a consequence of the mutation of the chloride channel gene on the 17th chromosome. These patients have a high risk of developing malignant hyperthermia during anesthesia, and call for full preparation to prevent and deal with this complication. Key words: Becker’s disease; Myotonia congenita; Anesthesia; Malignant hyperthermia Citation: Hasan SS. Anesthetic management of a patient with myotonia congenita. Anaesth. pain intensive care 2021;25(6):816–818 ; DOI: 10.35975/apic.v25i6.1712 Received: August 25, 2021, Reviewed: September 19, 2021, Accepted: October 03, 2021

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Braz, Luís, Ricardo Soares-dos-Reis, Mafalda Seabra, Fernando Silveira, and Joana Guimarães. "Brody disease: when myotonia is not myotonia." Practical Neurology 19, no. 5 (April 17, 2019): 417–19. http://dx.doi.org/10.1136/practneurol-2019-002224.

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A 56-year-old man presented with painless impairment of muscle relaxation on vigorous contraction (eg, eyelid closure, hand grip, running). There were no episodes of paralysis, symptom progression, weakness or extramuscular symptoms. Five of his fifteen siblings had similar complaints. His serum creatine kinase was normal. Electromyography showed electrical silence on muscle relaxation, without myotonic discharges. DMPK, ClCN1 and SCN4A genetic testing was normal, but he had a homozygous pathogenic variant of ATP2A1 (c.1315G>A; pGlu439Lys). Brody disease is a rare autosomal recessive myopathy due to ATP2A1 mutations that reduce sarcoplasmic reticulum calcium-ATPase1 activity, hence delaying muscle relaxation.

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Nadaj-Pakleza, Aleksandra. "Hypertrophie musculaire : signe de bonne santé ou de maladie ?" Les Cahiers de Myologie, no. 25 (July 2022): 10–15. http://dx.doi.org/10.1051/myolog/202225004.

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In order to explain muscle hypertrophy in a patient complaining of muscular symptoms one must take into account the patient’s daily professional or leisure physical activity. If muscle hypertrophy cannot be attributed to active lifestyle, an underlying neuromuscular pathology should be suspected. The check-up includes a meticulous neurological examination (looking for myotonia, rippling, myoclonus, etc.), a CK level dosage, an electromyography (for myotonic discharges), and, if necessary, it should be completed by muscle biopsy and molecular examinations. Several diagnostic hypotheses should be considered. Most are related to a genetic defect leading to dysfunction of the excitation-contraction coupling in the muscle. The diagnosis of a myotonic syndrome is the most common but caveolinopathy 3, RYR1-related myopathy or Brody’s disease are also possible.

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Hill, SL, GD Shelton, and TM Lenehan. "Myotonia in a cocker spaniel." Journal of the American Animal Hospital Association 31, no. 6 (November 1, 1995): 506–9. http://dx.doi.org/10.5326/15473317-31-6-506.

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A 16-week-old, male cocker spaniel suffering from pelvic-limb "bunny hopping" as well as rigidity, spasticity, and ataxia in all limbs was evaluated. The clinical features, electrophysiological abnormalities, and muscle histopathological and histochemical evaluations led to a diagnosis of congenital myotonia. Myotonia is a disorder of skeletal muscle characterized by delayed relaxation of the muscle fiber in response to voluntary, mechanical, or electrical stimulation. The pathophysiology of congenital myotonia remains controversial; currently proposed pathomechanisms are discussed. To the authors' knowledge, this is the first case of congenital myotonia reported in a cocker spaniel.

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Anderson, B. J., and T. C. K. Brown. "Congenital Myotonic Dystrophy in Children — A Review of Ten Years’ Experience." Anaesthesia and Intensive Care 17, no. 3 (August 1989): 320–24. http://dx.doi.org/10.1177/0310057x8901700313.

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A review of the anaesthetic management of children with congenital myotonic dystrophy anaesthetised at the Royal Children's Hospital over the past ten years is presented. Seven children underwent a total of fourteen anaesthetics. Anaesthetic considerations must include the degree of muscle weakness and hypotonia altering muscle relaxant requirements, aspiration risk due to palatopharyngeal dysfunction, and cardiomyopathy. Succinylcholine caused muscle contracture in a patient without clinical myotonia. This drug should be avoided. Although a low threshold to institute postoperative respiratory support must exist when treating neonates and infants, the older children did not clinically exhibit increased sensitivity to respiratory depressant drugs.

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Sugino, M., N. Ohsawa, T. Ito, S. Ishida, H. Yamasaki, F. Kimura, and K. Shinoda. "A pilot study of dehydroepiandrosterone sulfate in myotonic dystrophy." Neurology 51, no. 2 (August 1998): 586–89. http://dx.doi.org/10.1212/wnl.51.2.586.

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We studied the effect of IV administration of a dehydroepiandrosterone sulfate (DHEAS) preparation (200 mg/day for 8 weeks) in 11 patients with myotonic dystrophy (MyD). After DHEAS, activities of daily living improved, muscle strength increased, and myotonia decreased. Conduction block and premature beats also improved in the four patients with cardiac involvement. This pilot study may provide a rationale for a controlled study of DHEAS in MyD.

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Papadimas, Georgios K., Constantinos Papadopoulos, Kyriaki Kekou, Chrisoula Kartanou, Athina Kladi, Evangelia Nitsa, Christalena Sofocleous, et al. "A Greek National Cross-Sectional Study on Myotonic Dystrophies." International Journal of Molecular Sciences 23, no. 24 (December 7, 2022): 15507. http://dx.doi.org/10.3390/ijms232415507.

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Myotonic Dystrophies (DM, Dystrophia Myotonia) are autosomal dominant inherited myopathies with a high prevalence across different ethnic regions. Despite some differences, mainly due to the pattern of muscle involvement and the age of onset, both forms, DM1 and DM2, share many clinical and genetic similarities. In this study, we retrospectively analyzed the medical record files of 561 Greek patients, 434 with DM1 and 127 with DM2 diagnosed in two large academic centers between 1994–2020. The mean age at onset of symptoms was 26.2 ± 15.3 years in DM1 versus 44.4 ± 17.0 years in DM2 patients, while the delay of diagnosis was 10 and 7 years for DM1 and DM2 patients, respectively. Muscle weakness was the first symptom in both types, while myotonia was more frequent in DM1 patients. Multisystemic involvement was detected in the great majority of patients, with cataracts being one of the most common extramuscular manifestations, even in the early stages of disease expression. In conclusion, the present work, despite some limitations arising from the retrospective collection of data, is the first record of a large number of Greek patients with myotonic dystrophy and emphasizes the need for specialized neuromuscular centers that can provide genetic counseling and a multidisciplinary approach.

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Bell, E., A. R. Lorimer, and J. Hinnie. "Association between Myotonic Dystrophy and Primary Hyperparathyroidism." Journal of International Medical Research 22, no. 5 (September 1994): 296–98. http://dx.doi.org/10.1177/030006059402200508.

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A case of primary hyperparathyroidism in a patient with myotonic dystrophy is reported. A 56-year old female with myotonic dystrophy, admitted to hospital with a urinary tract infection, had widespread muscle atrophy and myotonia with bilateral cataracts. Biochemical findings of normal renal function but raised blood calcium, depressed blood phosphate and increased parathyroid hormone, were consistent with a diagnosis of primary hyperparathyroidism. Thallium scanning of the parathyroids showed an area of discordant thallium suggesting a parathyroid adenoma. When the left lower parathyroid was later excised, histology was consistent with the diagnosis of parathyroid adenoma. As far as the authors are aware this is the first report of myotonic dystrophy and primary hyperparathyroidism in the same patient.

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Arnold, W. David, David Kline, Alan Sanderson, Ahmed A. Hawash, Amy Bartlett, Kevin R. Novak, Mark M. Rich, and John T. Kissel. "Open-label trial of ranolazine for the treatment of myotonia congenita." Neurology 89, no. 7 (July 14, 2017): 710–13. http://dx.doi.org/10.1212/wnl.0000000000004229.

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Objective:To determine open-label, pilot study whether ranolazine could improve signs and symptoms of myotonia and muscle stiffness in patients with myotonia congenita (MC).Methods:Thirteen participants were assessed at baseline and 2, 4, and 5 weeks. Ranolazine was started after baseline assessment (500 mg twice daily), increased as tolerated after week 2 (1,000 mg twice daily), and maintained until week 4. Outcomes included change from baseline to week 4 in self-reported severity of symptoms (stiffness, weakness, and pain), Timed Up and Go (TUG), hand grip and eyelid myotonia, and myotonia on EMG.Results:Self-reported severity of stiffness (p < 0.0001) and weakness (p < 0.01) was significantly improved compared with baseline. TUG and grip myotonia times were reduced (p = 0.03, p = 0.01). EMG of the abductor digiti minimi and tibialis anterior showed significantly reduced myotonia duration (p < 0.001, p < 0.01) at week 4. No participant discontinued ranolazine because of side effects.Conclusions:Ranolazine appeared to be well tolerated over a period of 4 weeks in individuals with MC, and ranolazine resulted in improvement of signs and symptoms of muscle stiffness. The findings of this study suggest that ranolazine should be investigated in a larger controlled study.Classification of evidence:This study provides Class IV evidence that ranolazine improves myotonia in myotonia congenita.

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25

Braga, I. S., K. Oda, T. Kikuchi, S. Tanaka, Y. Shin, M. Sento, C. Itakura, and M. Mizutani. "A New Inherited Muscular Disorder in Japanese Quails (Coturnix coturnix japonica)." Veterinary Pathology 32, no. 4 (July 1995): 351–60. http://dx.doi.org/10.1177/030098589503200403.

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Thirteen adult mutant (LWC strain) Japanese quails ( Coturnix coturnix japonica), between the ages of 8 and 60 weeks were examined for a progressive muscular disorder. The disorder, inherited as an autosomal dominant trait, was clinically apparent as early as 28 days of age; it was characterized by generalized myotonia, muscle stiffness, and muscle weakness. Affected birds were identified by their inability to lift their wings vertically upward and by their inability to right themselves when placed on their dorsum. Electromyographic studies in two mutant quails showed high-frequency repetitive discharges comparable to those of myotonic runs. These discharges persisted after nerve resection. The distinctive histopathologic changes in the various muscles examined were ring fibers, sarcoplasmic masses, and internal migration of sarcolemmal nuclei. A slight decrease in the size of type IIB muscle fibers and a slight increase in the size of type IIA fibers were observed in the M. pectoralis thoracicus of affected quails. In older affected birds, inter- and intrafascicular fatty infiltration with replacement of type IIB fibers by fat cells was seen in the pectoral muscles. Single fiber necrosis, nonspecific lymphorrages, and variations in the muscle fiber size and shape were also noted. The typical muscle lesions and multisystem involvement, which was manifested by testicular degeneration and atrophy in the male LWC specimens and bilateral lenticular cataracts in 6 of 13 affected mutant quails, suggest resemblance of this new inherited muscular disorder to myotonic dystrophy in man.

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Cea, Gabriel, Daniel Andreu, Elaine Fletcher, Sithara Ramdas, Richa Sud, Michael G. Hanna, and Emma Matthews. "Sodium channel myotonia may be associated with high-risk brief resolved unexplained events." Wellcome Open Research 5 (March 31, 2020): 57. http://dx.doi.org/10.12688/wellcomeopenres.15798.1.

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Brief resolved unexplained events (BRUEs) have numerous and varied causes posing a challenge to investigation and management. A subset of infants with the neuromuscular disorder sodium channel myotonia, due to mutations in the SCN4A gene, experience apnoeic events due to laryngospasm (myotonia) of the upper airway muscles that may present as a BRUE. We sought to ascertain the frequency, severity and outcome of infants carrying the G1306E SCN4A mutation commonly associated with this presentation. We report 12 new cases of individuals with the G1306E mutation from three unrelated families and perform a literature review of all published cases. Infants with the G1306E mutation almost universally experience laryngospasm and apnoeic events. The severity varies significantly, spans both low and high-risk BRUE categories or can be more severe than criteria for a BRUE would allow. At least a third of cases require intensive care unit (ICU) care. Seizure disorder is a common erroneous diagnosis. Apnoeas are effectively reduced or abolished by appropriate treatment with anti-myotonic agents. Probands with the G1306E mutation who are family planning need to be counselled for the likelihood of post-natal complications. There is readily available and extremely effective treatment for the episodic laryngospasm and apnoea caused by this mutation. Proactively seeking clinical evidence of myotonia or muscle hypertrophy with consideration of CK and EMG in high risk BRUEs or more complex apnoeic events may reduce avoidable and prolonged ICU admissions, patient morbidity and potentially mortality.

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Cea, Gabriel, Daniel Andreu, Elaine Fletcher, Sithara Ramdas, Richa Sud, Michael G. Hanna, and Emma Matthews. "Sodium channel myotonia may be associated with high-risk brief resolved unexplained events." Wellcome Open Research 5 (May 12, 2020): 57. http://dx.doi.org/10.12688/wellcomeopenres.15798.2.

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Анотація:

Brief resolved unexplained events (BRUEs) have numerous and varied causes posing a challenge to investigation and management. A subset of infants with the neuromuscular disorder sodium channel myotonia, due to mutations in the SCN4A gene, experience apnoeic events due to laryngospasm (myotonia) of the upper airway muscles that may present as a BRUE. We sought to ascertain the frequency, severity and outcome of infants carrying the G1306E SCN4A mutation commonly associated with this presentation. We report 14 new cases of individuals with the G1306E mutation from three unrelated families and perform a literature review of all published cases. Infants with the G1306E mutation almost universally experience laryngospasm and apnoeic events. The severity varies significantly, spans both low and high-risk BRUE categories or can be more severe than criteria for a BRUE would allow. At least a third of cases require intensive care unit (ICU) care. Seizure disorder is a common erroneous diagnosis. Apnoeas are effectively reduced or abolished by appropriate treatment with anti-myotonic agents. Probands with the G1306E mutation who are family planning need to be counselled for the likelihood of post-natal complications. There is readily available and extremely effective treatment for the episodic laryngospasm and apnoea caused by this mutation. Proactively seeking clinical evidence of myotonia or muscle hypertrophy with consideration of CK,EMG and genetic testing in high risk BRUEs or more complex apnoeic events may reduce avoidable and prolonged ICU admissions, patient morbidity and potentially mortality.

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Varkey, B. "Muscle hypertrophy in myotonia congenita." Journal of Neurology, Neurosurgery & Psychiatry 74, no. 3 (March 1, 2003): 338. http://dx.doi.org/10.1136/jnnp.74.3.338.

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Su, Tzu-Rong, Wen-Shan Zei, Ching-Chyuan Su, George Hsiao, and Min-Jon Lin. "The Effects of the KCNQ Openers Retigabine and Flupirtine on Myotonia in Mammalian Skeletal Muscle Induced by a Chloride Channel Blocker." Evidence-Based Complementary and Alternative Medicine 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/803082.

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The purpose of this study was to investigate the effect of KCNQ (potassium channel, voltage-gated, KQT-like subfamily) openers in preventing myotonia caused by anthracene-9-carboxylic acid (9-AC, a chloride channel blocker). An animal model of myotonia can be elicited in murine skeletal muscle by 9-AC treatment. KCNQ openers, such as retigabine and flupirtine, can inhibit the increased twitch amplitude (0.1 Hz stimulation) and reduce the tetanic fade (20 Hz stimulations) observed in the presence of 9-AC. Furthermore, the prolonged twitch duration of skeletal muscle was also inhibited by retigabine or flupirtine. Lamotrigine (an anticonvulsant drug) has a lesser effect on the muscle twitch amplitude, tetanic fade, and prolonged twitch duration as compared with KCNQ openers. In experiments using intracellular recordings, retigabine and flupirtine clearly reduced the firing frequencies of repetitive action potentials induced by 9-AC. These data suggested that KCNQ openers prevent the myotonia induced by 9-AC, at least partly through enhancing potassium conductance in skeletal muscle. Taken together, these results indicate that KCNQ openers are potential alternative therapeutic agents for the treatment of myotonia.

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Ketley, Ami, Marzena Wojciechowska, Sonja Ghidelli-Disse, Paul Bamborough, Tushar K. Ghosh, Marta Lopez Morato, Saam Sedehizadeh, et al. "CDK12 inhibition reduces abnormalities in cells from patients with myotonic dystrophy and in a mouse model." Science Translational Medicine 12, no. 541 (April 29, 2020): eaaz2415. http://dx.doi.org/10.1126/scitranslmed.aaz2415.

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Myotonic dystrophy type 1 (DM1) is an RNA-based disease with no current treatment. It is caused by a transcribed CTG repeat expansion within the 3′ untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. Mutant repeat expansion transcripts remain in the nuclei of patients’ cells, forming distinct microscopically detectable foci that contribute substantially to the pathophysiology of the condition. Here, we report small-molecule inhibitors that remove nuclear foci and have beneficial effects in the HSALR mouse model, reducing transgene expression, leading to improvements in myotonia, splicing, and centralized nuclei. Using chemoproteomics in combination with cell-based assays, we identify cyclin-dependent kinase 12 (CDK12) as a druggable target for this condition. CDK12 is a protein elevated in DM1 cell lines and patient muscle biopsies, and our results showed that its inhibition led to reduced expression of repeat expansion RNA. Some of the inhibitors identified in this study are currently the subject of clinical trials for other indications and provide valuable starting points for a drug development program in DM1.

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Yadava, Ramesh S., Yun K. Kim, Mahua Mandal, Karunasai Mahadevan, Jordan T. Gladman, Qing Yu, and Mani S. Mahadevan. "MBNL1 overexpression is not sufficient to rescue the phenotypes in a mouse model of RNA toxicity." Human Molecular Genetics 28, no. 14 (April 1, 2019): 2330–38. http://dx.doi.org/10.1093/hmg/ddz065.

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Abstract Myotonic dystrophy type 1 (DM1) is caused by an expanded (CTG)n tract in the 3′UTR of the DM protein kinase (DMPK) gene. The RNA transcripts produced from the expanded allele sequester or alter the function of RNA-binding proteins (MBNL1, CUGBP1, etc.). The sequestration of MBNL1 results in RNA-splicing defects that contribute to disease. Overexpression of MBNL1 in skeletal muscle has been shown to rescue some of the DM1 features in a mouse model and has been proposed as a therapeutic strategy for DM1. Here, we sought to confirm if overexpression of MBNL1 rescues the phenotypes in a different mouse model of RNA toxicity. Using an inducible mouse model of RNA toxicity in which expression of the mutant DMPK 3′UTR results in RNA foci formation, MBNL1 sequestration, splicing defects, myotonia and cardiac conduction defects, we find that MBNL1 overexpression did not rescue skeletal muscle function nor beneficially affect cardiac conduction. Surprisingly, MBNL1 overexpression also did not rescue myotonia, though variable rescue of Clcn1 splicing and other splicing defects was seen. Additionally, contrary to the previous study, we found evidence for increased muscle histopathology with MBNL1 overexpression. Overall, we did not find evidence for beneficial effects from overexpression of MBNL1 as a means to correct RNA toxicity mediated by mRNAs containing an expanded DMPK 3′UTR.

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Finsterer, J., C. Stöllberger, A. Reining-Festa, M. Loewe-Grgurin, and M. Gencik. "Myotonic dystrophy-2: Unusual phenotype due to a small CCTG-expansion." Balkan Journal of Medical Genetics 21, no. 2 (December 31, 2018): 39–43. http://dx.doi.org/10.2478/bjmg-2018-0024.

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Abstract Myotonic dystrophy type 2 (MD2) is a multisystem disease, predominantly affecting the proximal limb muscles, eyes, endocrine organs, heart and intestines. Longterm asymptomatic creatine kinase (hyper-CKemia) of more than 20 years duration, in association with hyperlipidemia and diabetes, as a manifestation of MD2 has not been reported. A 52-year-old female with a history of hyper-CKemia since the age of 32 years associated with diabetes, hyperlipidemia and hyperuricemia, developed anginal chest pain and proximal muscle weakness together with clinical myotonia when opening the fists at age 51 years. Examination revealed a left anterior hemiblock, sensorimotor neuropathy, extensive myotonic discharges on needle electromyography (EMG) and a CCTG-expansion of 134 bp on the ZNF9 gene. The family history was positive for hyper-CKemia and muscle weakness. In addition, over the previous years, she had developed vesico-ureteral reflux, cutaneous melanoma, renal cysts, cervix dysplasias, thrombocytosis, cataracts, arterial hypertension, heterozygous Factor V Leiden mutation, cholecystolithiasis, multiple ovarial cysts and vitamin D deficiency. Asymptomatic, long-term hyper-CKemia in association with multisystem disease should raise the suspicion of a MD2. Rare manifestations of MD2 may be thrombocytosis, hyperuricemia, vesico-ureteral reflux, gallstones, hypertension and cyst formation. In patients with asymptomatic hyper-CKemia, needle EMG should be considered. Myotonic dystrophy type 2 may take a mild course over many years if the CCTG-expansion is short.

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Troshina, Ekaterina A., Elena A. Panfilova, and Taras S. Panevin. "Autoimmune polyglandular disorders in myotonic dystrophy." Problems of Endocrinology 65, no. 3 (September 12, 2019): 155–60. http://dx.doi.org/10.14341/probl9775.

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Myotonic dystrophy (MD) is the most common muscle disorder in adults. MD is a hereditary disease with an autosomal dominant mode of inheritance, almost 100% penetrance and pronounced clinical polymorphism. The mechanism for the development of the disease is that a mutation of the DMPK (dystrophia myotonica protein kinase) gene disrupts the normal metabolism of RNA, which leads to a defect in the maturation and translation of mRNA. The disorder in the DMPK gene affects not only striated musculature, but also smooth myocytes and cardiomyocytes. The main clinical symptom that distinguishes MD from others is a spontaneous or provoked inability to relax muscles (myotonia phenomenon). Endocrine disorders arising from type 1 MD (MD1) with a higher than average frequency in the population include hypergonadotropic hypogonadism, impaired glucose tolerance with hyperinsulinism, and insulin resistance. Thyroid function may remain normal, although many cases of autoimmune thyroiditis resulting in hypothyroidism, as well as Graves’ disease, have been described. A description is given of a patient suffering from MD1 with a number of endocrine disorders, including hypergonadotropic hypogonadism, autoimmune thyroid disease, hyperinsulinism, and also impaired calcium-phosphorus metabolism. Important features are the absence of any significant complaints from the muscular system in the presence of an increase in creatine phosphokinase (CPK), which is characteristic of this disease, as well as the temporal dynamics of thyroid status and the nature of the autoimmune thyroid disease.

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De Bellis, Michela, Brigida Boccanegra, Alessandro Giovanni Cerchiara, Paola Imbrici, and Annamaria De Luca. "Blockers of Skeletal Muscle Nav1.4 Channels: From Therapy of Myotonic Syndrome to Molecular Determinants of Pharmacological Action and Back." International Journal of Molecular Sciences 24, no. 1 (January 3, 2023): 857. http://dx.doi.org/10.3390/ijms24010857.

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The voltage-gated sodium channels represent an important target for drug discovery since a large number of physiological processes are regulated by these channels. In several excitability disorders, including epilepsy, cardiac arrhythmias, chronic pain, and non-dystrophic myotonia, blockers of voltage-gated sodium channels are clinically used. Myotonia is a skeletal muscle condition characterized by the over-excitability of the sarcolemma, resulting in delayed relaxation after contraction and muscle stiffness. The therapeutic management of this disorder relies on mexiletine and other sodium channel blockers, which are not selective for the Nav1.4 skeletal muscle sodium channel isoform. Hence, the importance of deepening the knowledge of molecular requirements for developing more potent and use-dependent drugs acting on Nav1.4. Here, we review the available treatment options for non-dystrophic myotonia and the structure–activity relationship studies performed in our laboratory with a focus on new compounds with potential antimyotonic activity.

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Wakeman, Bradley, Deepti Babu, Jack Tarleton, and Ian M. MacDonald. "Extraocular muscle hypertrophy in myotonia congenita." Journal of American Association for Pediatric Ophthalmology and Strabismus 12, no. 3 (June 2008): 294–96. http://dx.doi.org/10.1016/j.jaapos.2007.12.002.

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SUNOHARA, Nobuhiko, Hideaki TOMI, Akinori NAKAMURA, Kiichi ARAHATA, and Ikuya NONAKA. "Myotonia Congenita with Painful Muscle Cramps." Internal Medicine 35, no. 6 (1996): 507–11. http://dx.doi.org/10.2169/internalmedicine.35.507.

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Varga, Dávid, and Endre Pál. "A dystrophia myotonica 1-es típusának sokszervi megjelenése." Orvosi Hetilap 160, no. 37 (September 2019): 1447–54. http://dx.doi.org/10.1556/650.2019.31505.

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Abstract: Myotonic dystrophy is one of the most common, autosomal dominantly inherited adult-onset muscle disorders. Two types of the disease are known: type 1 is characterized by distal weakness and myotonia, but type 2 is associated with proximal weakness and milder clinical course. It is also called as Steinert Disease, which affects the heart conduction system, the internal secretional glands, the ocular lens as well as carbohydrate-, fat metabolism and gonadal functions. These systemic symptoms have high impact on the quality of life and might impact on patients’ survival. Here we would like to emphasize these clinical conditions and the diagnostic possibilities. We hope our recommendations can help neurologists and general practitioners to achieve an optimal and individual care for patients suffering from this muscle disease. Orv Hetil. 2019; 160(37): 1447–1454.

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McGreal, Analise, Daniel Slagle, and Andrew Dickens. "Case Report: General Anesthetic Management for Laparoscopic Cholecystectomy in Paramyotonia Congenita." International Journal of Medical Students 8, no. 3 (December 9, 2020): 288–90. http://dx.doi.org/10.5195/ijms.2020.604.

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Анотація:

Background: Paramyotonia congenita (PC) is a rare disorder affecting skeletal muscle. Patients with this non-progressive condition experience intermittent episodes of sustained myotonia. Due to the predisposition for prolonged muscle contraction, special attention must be given to anesthetic management during operative procedures to prevent complications similar to those experienced in patients with malignant hyperthermia. To date, however, limited reports of anesthetic management in paramyotonia congenita are available. The Case: The present report describes successful general anesthetic management given to a patient with paramyotonia congenita using propofol and ketamine for induction, non-depolarizing rocuronium for muscle paralysis, and continuous nitrous oxide and IV propofol infusion for sedation. The patient remained stable throughout the case without myotonic episodes or other complications. Conclusion: Our report describes successful anesthetic management in a patient with paramyotonia congenita. This provides a potential management plan that may be applied to PC patients undergoing a variety of surgical procedures and eliminates risk associated with succinylcholine and possibly volatile anesthetics. Further research is needed to determine whether this approach is superior to previously reported techniques and should also identify which agents may be effectively utilized to reverse an intra-operative myotonic episode in PC.

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Ricker, K., M. C. Koch, F. Lehmann-Horn, D. Pongratz, M. Otto, R. Heine, and R. T. Moxley. "Proximal myotonic myopathy: A new dominant disorder with myotonia, muscle weakness, and cataracts." Neurology 44, no. 8 (August 1, 1994): 1448. http://dx.doi.org/10.1212/wnl.44.8.1448.

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Milone, Margherita, Sat D. Batish, and Jasper R. Daube. "Myotonic dystrophy type 2 with focal asymmetric muscle weakness and no electrical myotonia." Muscle & Nerve 39, no. 3 (March 2009): 383–85. http://dx.doi.org/10.1002/mus.21150.

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Scola, Rosana Herminia, Fabio Massaiti Iwamoto, Carlos Henrique Camargo, Walter Oleschko Arruda, and Lineu Cesar Werneck. "Myotonia congenita and myoadenylate deaminase deficiency: case report." Arquivos de Neuro-Psiquiatria 61, no. 2A (June 2003): 262–64. http://dx.doi.org/10.1590/s0004-282x2003000200019.

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Анотація:

Approximately 1-2% of the population has a deficiency of the enzyme myoadenylate deaminase. Early reports suggested that patients with myoadenylate deaminase deficiency had various forms of myalgia, and exercise intolerance. However, a deficiency of the enzyme has been described in many conditions, including myopathies, neuropathies, and motor neuron disease. We report a patient with clinical diagnosis of myotonia congenita and absent myoadenylate deaminase reaction on the muscle biopsy. This is the first description of myoadenilate deaminase deficiency with myotonia congenita. Myoadenylate deaminase deficiency is the most common enzymatic deficit of muscle, and the association with other neuromuscular diseases is coincidental.

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Tanigasalam, Vasanthan. "Myotonia in a child with muscle hypertrophy." Indian Pediatrics 54, no. 1 (January 2017): 58. http://dx.doi.org/10.1007/s13312-017-1000-y.

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Kwiecińaski, Hubert, Frank Lehmann-Horn, and Reinhardt Rüdel. "Drug-induced myotonia in human intercostal muscle." Muscle & Nerve 11, no. 6 (June 1988): 576–81. http://dx.doi.org/10.1002/mus.880110609.

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Kim, Youn Kyoung, and Sa-Yoon Kang. "Hyperkalemic Periodic Paralysis Caused by a Mutation in the Sodium Channel SCN4A Gene." Journal of Medicine and Life Science 11, no. 1 (June 1, 2014): 5–7. http://dx.doi.org/10.22730/jmls.2014.11.1.5.

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Hyperkalemic periodic paralysis (HyperPP) is an autosomal dominant muscle sodium channelopathy characterized by recurrentepisode of reversible paralysis with concomitant hyperkalemia. The diagnosis of HyperPP is suggested by a history of attacks ofparalysis, positive family history, and the presence of myotonia. A 19-year-old man presented with recurrent generalized limbweakness since childhood. The paralysis often followed by fatigue, exercise, and fasting. His parents were clinically unaffectedand had never experienced paralytic symptoms. Electromyographic evaluation demonstrated myotonic discharge. Directsequencing of SCN4A exon 24 revealed a heterozygous A>G transition at nucleotide 4774, resulting in the substitution of amethionine by a valine at codon 1592 (Met1592Val). We report a patient with HyperPP confirmed by Met1592Val mutation inSCN4A gene.

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Brooks, EK, D. Schweitzer, and HL Robinson. "A case of paramyotonia congenita in pregnancy." Obstetric Medicine 13, no. 4 (January 31, 2019): 192–94. http://dx.doi.org/10.1177/1753495x18816171.

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Анотація:

Paramyotonia congenita is a rare autosomal dominant non-dystrophic myopathy caused by mutations in the SNC4A gene, which encodes for the voltage-gated sodium channel in skeletal muscle. Symptom onset is typically during early childhood and is characterised by myotonia followed by flaccid paralysis or weakness, usually exacerbated by repeated muscle contractions or cold temperatures. Pregnancy has been reported to increase symptoms of myotonia; however, there is limited information in the literature regarding the possible effects of paramyotonia congenita on pregnancy and labour. We present a successful case of a 20-year-old primigravida with confirmed paramyotonia congenita and review the literature regarding paramyotonia congenita during pregnancy.

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Moxley, Richard T., Eric L. Logigian, William B. Martens, Chris L. Annis, Shree Pandya, Richard T. Moxley, Cheryl A. Barbieri, Nuran Dilek, Allen W. Wiegner, and Charles A. Thornton. "Computerized hand grip myometry reliably measures myotonia and muscle strength in myotonic dystrophy (DM1)." Muscle & Nerve 36, no. 3 (2007): 320–28. http://dx.doi.org/10.1002/mus.20822.

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Koehorst, Emma, Alfonsina Ballester-Lopez, Virginia Arechavala-Gomeza, Alicia Martínez-Piñeiro, and Gisela Nogales-Gadea. "The Biomarker Potential of miRNAs in Myotonic Dystrophy Type I." Journal of Clinical Medicine 9, no. 12 (December 4, 2020): 3939. http://dx.doi.org/10.3390/jcm9123939.

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MicroRNAs (miRNAs) are mostly known for their gene regulation properties, but they also play an important role in intercellular signaling. This means that they can be found in bodily fluids, giving them excellent biomarker potential. Myotonic Dystrophy type I (DM1) is the most frequent autosomal dominant muscle dystrophy in adults, with an estimated prevalence of 1:8000. DM1 symptoms include muscle weakness, myotonia, respiratory failure, cardiac conduction defects, cataracts, and endocrine disturbances. Patients display heterogeneity in both age of onset and disease manifestation. No treatment or cure currently exists for DM1, which shows the necessity for a biomarker that can predict disease progression, providing the opportunity to implement preventative measures before symptoms arise. In the past two decades, extensive research has been conducted in the miRNA expression profiles of DM1 patients and their biomarker potential. Here we review the current state of the field with a tissue-specific focus, given the multi-systemic nature of DM1 and the intracellular signaling role of miRNAs.

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Fadoum, Hassan, Ibrahim Idriss Deka, Hlal Safa, Chikhi Fatima, Fellat Ibtissam, and Cherti Mohamed. "BIFASCICULAR BLOCK REVEALING STEINERTS MYOTONIC DYSTROPHY." International Journal of Advanced Research 10, no. 02 (February 28, 2022): 652–59. http://dx.doi.org/10.21474/ijar01/14250.

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Steinerts disease or myotonic dystrophy type 1 is a genetic neuromuscular disorder with autosomal dominant transmission. It leads to multisystemic damage, including a cardiac localization that is life-threatening.We report the case of a 55 year old patient, without cardiovascular risk factors, with a history of distal muscle damage since the age of 25 years, in his family history we find a brother followed for an unlabelled skeletal muscle damage.He consulted for exertional dyspnea and lipothymic discomfort. The clinical examination revealed a decrease in muscle strength in the lower limbs with amyotrophy. Walking is difficult with the help of crutches and the patient uses a wheelchair. The neurological investigation concluded in Steinerts myotonic dystrophy on the electromyogram.The patients ECG showed a bifascicular block consisting of a left anterior hemiblock and a complete right bundle branch block. The echocardiography did not show any structural abnormalities but found a disturbance of the LV relaxation on the mitral profile.The electrophysiological exploration carried out for the measurement of infrahisical conduction revealed a long HV at 100ms indicating the implantation of a double chamber stimulation.The interest of reporting this case was to underline the importance of screening for cardiac damage of rhythmic origin. But also to inform with the help of literature data the incidence of these forms and the place of cardiac stimulation in the prevention of sudden death in steinerts myotonia.

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Kornblum, C., J. Reimann, and M. P. Wattjes. "Response: skeletal muscle MRI in recessive myotonia congenita." Acta Neurologica Scandinavica 124, no. 2 (July 7, 2011): 148. http://dx.doi.org/10.1111/j.1600-0404.2011.01487.x.

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Baumann, P., P. Siira, H. Vanharanta, and V. V. Myllylä. "Quantification of Muscle Strength in Recessive Myotonia congenita." European Neurology 36, no. 5 (1996): 284–87. http://dx.doi.org/10.1159/000117273.

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