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Journal articles on the topic 'Myotonia'

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Published: 4 June 2021

Last updated: 9 June 2025

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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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Rahimova, N. J., and A. K. Mamedbeyli. "THE NONDYSTROPHIC MYOTONIAS (CLINICAL CASE, DISCUSSION)." National Journal of Neurology 1, no. 09 (July 30, 2016): 90–97. http://dx.doi.org/10.61788/njn.v1i16.15.

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The article presents the clinical case of congenital myotonia which was newly diagnosed in patients with back pain. It has been discussed the genetics, pathophysiology, clinical features, differential diagnosis and management for myotonic syndrome due to different nondystrophic myotonias.

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Finsterer, Josef, Georg Safoschnik, and Martina Witsch-Baumgartner. "Marathoning with myotonic dystrophy type 2 (proximal myotonic myopathy) and leukopenia." SAGE Open Medical Case Reports 5 (January 1, 2017): 2050313X1770302. http://dx.doi.org/10.1177/2050313x17703021.

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Objectives: A mild, slowly progressive course of proximal myotonic myopathy, also known as myotonic dystrophy type 2, over years allowing the patient to continue with extreme sport activity, has been only rarely reported. Methods: Case report. Results: The patient is a 54-year-old female sport teacher who developed myotonia of the distal upper limbs at the age of 32 years. Over the following 22 years, myotonia spreaded to the entire musculature. Myotonia did not prevent her from doing her job and from marathoning and improved with continuous exercise. Additionally, she had developed hypothyroidism, ovarial cysts, incipient cataract, motor neuropathy, hepatopathy, leukopenia, and mild hyper-CK-emia. A heterozygous CCTG-repeat expansion of 500–9500 was found in the CNBP/ZNF9 gene. At the age of 54 years, she was still performing sport, without presenting with myotonia on clinical examination or having developed other typical manifestations of proximal myotonic myopathy. Conclusions: This case shows that proximal myotonic myopathy may take a mild course over at least 22 years, that proximal myotonic myopathy with mild myotonia may allow a patient to continue strenuous sport activity, and that continuous physical activity may contribute to the mild course of the disease.

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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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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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Carter, Gregory T., Michael D. Weiss, and Thomas D. Bird. "Myotonic disorder without myotonia?" Muscle & Nerve 40, no. 6 (August 31, 2009): 1071–72. http://dx.doi.org/10.1002/mus.21418.

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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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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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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 (&gt; 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 (&gt; 64 microM) propofol (P &lt; 0.01). Halothane, isoflurane, or sevoflurane each enhanced the myotonic reactions at 5.4 (P &lt; 0.001), 0.21 (P &lt; 0.01), and 0.5 minimum alveolar concentrations (P &lt; 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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Yadava, Ramesh S., Qing Yu, Mahua Mandal, Frank Rigo, C. Frank Bennett, and Mani S. Mahadevan. "Systemic therapy in an RNA toxicity mouse model with an antisense oligonucleotide therapy targeting a non-CUG sequence within the DMPK 3′UTR RNA." Human Molecular Genetics 29, no. 9 (April 2, 2020): 1440–53. http://dx.doi.org/10.1093/hmg/ddaa060.

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Abstract Myotonic dystrophy type 1 (DM1), the most common adult muscular dystrophy, is an autosomal dominant disorder caused by an expansion of a (CTG)n tract within the 3′ untranslated region (3′UTR) of the dystrophia myotonica protein kinase (DMPK) gene. Mutant DMPK mRNAs are toxic, present in nuclear RNA foci and correlated with a plethora of RNA splicing defects. Cardinal features of DM1 are myotonia and cardiac conduction abnormalities. Using transgenic mice, we have demonstrated that expression of the mutant DMPK 3′UTR is sufficient to elicit these features of DM1. Here, using these mice, we present a study of systemic treatment with an antisense oligonucleotide (ASO) (ISIS 486178) targeted to a non-CUG sequence within the 3′UTR of DMPK. RNA foci and DMPK 3′UTR mRNA levels were reduced in both the heart and skeletal muscles. This correlated with improvements in several splicing defects in skeletal and cardiac muscles. The treatment reduced myotonia and this correlated with increased Clcn1 expression. Furthermore, functional testing showed improvements in treadmill running. Of note, we demonstrate that the ASO treatment reversed the cardiac conduction abnormalities, and this correlated with restoration of Gja5 (connexin 40) expression in the heart. This is the first time that an ASO targeting a non-CUG sequence within the DMPK 3′UTR has demonstrated benefit on the key DM1 phenotypes of myotonia and cardiac conduction defects. Our data also shows for the first time that ASOs may be a viable option for treating cardiac pathology in DM1.

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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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Chen, Annie V., Rodney S. Bagley, and Patricia A. Talcott. "Confirmed 2,4-Dichlorophenoxyacetic Acid Toxicosis in a Dog." Journal of the American Animal Hospital Association 46, no. 1 (January 1, 2010): 43–47. http://dx.doi.org/10.5326/0460043.

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A 2-year-old, intact male Weimaraner was evaluated for episodic extensor rigidity and a stiff gait of 24 hours’ duration. Percussion of the proximal appendicular muscles with a reflex hammer resulted in formation of dimples consistent with myotonia. Electromyography identified myotonic potentials. Residues of 2,4-dichlorophenoxyacetic acid (2,4-D) were detected in both serum and urine. The dog was treated with intravenous fluid therapy for 36 hours, and clinical signs improved dramatically. Toxicosis with 2,4-D should be considered a differential for acquired myotonia in dogs with or without systemic signs. Exposed dogs with only clinical signs of myotonia can have good clinical outcomes. A confirmed clinical case of 2,4-D toxicosis in the dog has not previously been reported.

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Jose, A. Rey, Pham Huy, Blue Lauren, and Liriano Carolina. "A Case of Myotonia Congenita and Schizophrenia: Difficulties in Treatment with Antipsychotics due to Hypersensitivity to Extrapyramidal Symptoms." International Journal of Psychiatry and Mental Health 1, no. 1 (November 13, 2019): 38–43. https://doi.org/10.36811/ijpmh.2019.110006.

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Myotonia congenita is a rare non-dystrophic skeletal muscle disease characterized by an inability to relax skeletal muscles after abrupt voluntary movements. Patients with this condition have stiff muscles and difficulty with mobility, especially when initiating movement after periods of rest. It is well known that movement disorders are a common side effect of antipsychotics due to their ability to antagonize dopamine 2 receptors in the extrapyramidal part of the basal ganglia. The purpose of this case is to describe the effects antipsychotics had on a 59-year-old Caucasian male with comorbid myotonia congenita and schizophrenia in an inpatient psychiatric hospital setting. Medication trials of ziprasidone, haloperidol and clozapine exacerbated his myotonic symptoms leading to falls and complaints of severe muscle stiffness, which were relieved upon discontinuation of all antipsychotic medications. This suggests that patients with myotonia congenita may have an increased sensitivity to the extrapyramidal side effect profile of antipsychotics. Treatment options for this patient case are discussed with an emphasis on lamotrigine. <strong>Keywords:</strong> Myotonia congenita; Schizophrenia; Myopathy; Antipsychotics; Extrapyramidal symptoms

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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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Unni, Jiji V., Deepak Daryani, M. P. Uthkal, and Shabil Mohamed Mustafa. "An Unusual Case of Hybrid Odontogenic Tumor in Type 1 Myotonic Dystrophy Patient." International Journal of Applied & Basic Medical Research 13, no. 4 (2023): 255–58. http://dx.doi.org/10.4103/ijabmr.ijabmr_208_23.

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Abstract Myotonic dystrophy, also referred myotonic muscular dystrophy, is an autosomal dominant, slowly progressive, multisystem disease characterized by skeletal muscle weakness, wasting, and myotonia. A hybrid tumor of odontogenic apparatus is a lesion showing combined histopathological characteristics of two or more previously recognized odontogenic tumors and/or cysts of different categories. We, therefore, report a case of hybrid tumor (adenomatoid odontogenic tumor associated with calcifying cystic odontogenic tumor) in a myotonic dystrophic patient.

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Cannon, S. C., and D. P. Corey. "Loss of Na+ channel inactivation by anemone toxin (ATX II) mimics the myotonic state in hyperkalaemic periodic paralysis." Journal of Physiology 466, no. 1 (July 1993): 501–20. http://dx.doi.org/10.1113/jphysiol.1993.sp019731.

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1. Mutations that impair inactivation of the sodium channel in skeletal muscle have recently been postulated to cause several heritable forms of myotonia in man. A peptide toxin from Anemonia sulcata (ATX II) selectively disrupts the inactivation mechanism of sodium channels in a way that mimics these mutations. We applied ATX II to rat skeletal muscle to test the hypothesis that myotonia is inducible by altered sodium channel function. 2. Single‐channel sodium currents were measured in blebs of surface membrane that arose from the mechanically disrupted fibres. ATX II impaired inactivation as demonstrated by persistent reopenings of sodium channels at strongly depolarized test potentials. A channel failed to inactivate, however, in only a small proportion of the depolarizing steps. With micromolar amounts of ATX II, the ensemble average open probability at the steady state was 0.01‐0.02. 3. Ten micromolar ATX II slowed the relaxation of tension after a single twitch by an order of magnitude. Delayed relaxation is the in vitro analogue of the stiffness experienced by patients with myotonia. However, peak twitch force was not affected within the range of 0‐10 microM ATX II. 4. Intracellular injection of a long‐duration, constant current pulse elicited a train of action potentials in ATX II‐treated fibres. After‐depolarizations and repetitive firing often persisted beyond the duration of the stimulus. Trains of action potentials varied spontaneously in amplitude and firing frequency in a similar way to the electromyogram of a myotonic muscle. Both the after‐depolarization and the post‐stimulus firing were abolished by detubulating the fibres with glycerol. 5. We conclude that a loss of sodium channel inactivation alone, without changes in resting membrane conductance, is sufficient to produce the electrical and mechanical features of myotonia. Furthermore, in support of previous studies on myotonic muscle from patients, this model provides direct evidence that only a small proportion of sodium channels needs to function abnormally to cause myotonia.

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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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Kinney, Michelle A. O., and Barry A. Harrison. "Propofol-Induced Myotonia in Myotonic Dystrophy." Anesthesia & Analgesia 83, no. 3 (September 1996): 665–66. http://dx.doi.org/10.1097/00000539-199609000-00067.

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Child, John S., and Joseph K. Perloff. "Myocardial myotonia in myotonic muscular dystrophy." American Heart Journal 129, no. 5 (May 1995): 982–90. http://dx.doi.org/10.1016/0002-8703(95)90120-5.

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Milone, Margherita, and Jasper R. Daube. "Reply to: Myotonic disorder without myotonia?" Muscle & Nerve 40, no. 6 (December 2009): 1073. http://dx.doi.org/10.1002/mus.21416.

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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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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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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 &gt;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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Yamashita, Yuri, Satoshi Nakada, Kyoko Nakamura, Hidetoshi Sakurai, Kinji Ohno, Tomohide Goto, Yo Mabuchi, Chihiro Akazawa, Nobutaka Hattori, and Eri Arikawa-Hirasawa. "Evaluation of Human-Induced Pluripotent Stem Cells Derived from a Patient with Schwartz–Jampel Syndrome Revealed Distinct Hyperexcitability in the Skeletal Muscles." Biomedicines 11, no. 3 (March 7, 2023): 814. http://dx.doi.org/10.3390/biomedicines11030814.

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Schwartz–Jampel syndrome (SJS) is an autosomal recessive disorder caused by loss-of-function mutations in heparan sulfate proteoglycan 2 (HSPG2), which encodes the core basement membrane protein perlecan. Myotonia is a major criterion for the diagnosis of SJS; however, its evaluation is based solely on physical examination and can be challenging in neonates and young children. Furthermore, the pathomechanism underlying SJS-related myotonia is not fully understood, and effective treatments for SJS are limited. Here, we established a cellular model of SJS using patient-derived human-induced pluripotent stem cells. This model exhibited hyper-responsiveness to acetylcholine as a result of abnormalities in the perlecan molecule, which were confirmed via comparison of their calcium imaging with calcium imaging of satellite cells derived from Hspg2−/−-Tg mice, which exhibit myotonic symptoms similar to SJS symptoms. Therefore, our results confirm the utility of creating cellular models for investigating SJS and their application in evaluating myotonia in clinical cases, while also providing a useful tool for the future screening of SJS therapies.

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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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Beech, J., J. E. Fletcher, F. Lizzo, and J. Johnston. "Effect of phenytoin on the clinical signs and in vitro muscle twitch characteristics in horses with chronic intermittent rhabdomyolysis and myotonia." American Journal of Veterinary Research 49, no. 12 (December 1, 1988): 2130–33. https://doi.org/10.2460/ajvr.1988.49.12.2130.

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SUMMARY In vitro twitch characteristics of the semimembranosus muscle were evaluated in 9 clinically normal horses, in 15 horses with chronic intermittent rhabdomyolysis (cir) and in 2 horses with myotonia. Effects of phenytoin on in vitro muscle twitch and clinical signs of cie and myotonia were evaluated in these same horses. Times to 90% relaxation were prolonged in the horses with cir (mean ± sem, 186 ± 5.9 ms) and in 2 horses with myotonia (197 and 177 ms) compared with those in clinically normal horses (mean ± sem, 146 ±2.1 ms). Horses with cir also had significantly (P < 0.05) longer times to 50% relaxation, compared with clinically normal horses. In the group of horses with cir, Standardbreds had significantly (P < 0.05) longer times to 90% and 50% relaxation, compared with Thoroughbreds. Times to 100% peak tension did not differ among the groups. Administration of phenytoin directly into a muscle preparation bath solution had no effect on muscle twitch properties. After the initial muscle biopsy, phenytoin was administered orally for 7 to 10 days to 4 horses with cir, 2 myotonic horses, and 2 clinically normal horses before repeat biopsy from the same site in the contralateral semimembranosus muscle. Times to 90% relaxation decreased from 197 and 177 ms to 144 and 126 ms, respectively, in the 2 myotonic horses, from a mean of 192 (± 9) ms to 170 (± 9) ms in the 4 horses with cir and remained unchanged (154 and 140 ms before vs 155 and 139 ms after treatment) in the 2 clinically normal horses. Phenytoin treatment of 8 horses with cir was associated with excellent clinical response in 7; 1 horse became lame, which prevented evaluation of the drug, and the other horse with normal muscle twitch properties continued to have seasonally severe cir. Of the 9 horses with cir that were not treated, 4 were lost to evaluation, 3 continued to be affected (but 1 of these often performed well), and 3 were reported to perform satisfactorily. After 10 days of treatment, the 2 myotonic horses had no change in gait or myotonic dimpling and myotonic discharges persisted, although subjectively, they were slightly decreased. Phenytoin appears to be useful clinically for treating horses with cir.

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Sander, H. W., G. P. Tavoulareas, and S. Chokroverty. "Heat-sensitive myotonia in proximal myotonic myopathy." Neurology 47, no. 4 (October 1, 1996): 956–62. http://dx.doi.org/10.1212/wnl.47.4.956.

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Morton, Adam. "Myotonic disorders and pregnancy." Obstetric Medicine 13, no. 1 (March 16, 2019): 14–19. http://dx.doi.org/10.1177/1753495x18824238.

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Myotonic disorders represent significant risk in pregnancy due to their complexity and the risk of maternal and fetal complications. Care of these pregnancies requires detailed pre-conception counselling, close monitoring of mother and fetus during the pregnancy and a delivery and postpartum plan involving a multidisciplinary team approach. A case of a woman with myotonia congenita diagnosed in pregnancy is presented, the general principles of care of women with myotonic disorders discussed, and care of the specific conditions in pregnancy reviewed. Trial registration: Not applicable.

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Longman, C. "Myotonic dystrophy." Journal of the Royal College of Physicians of Edinburgh 36, no. 1 (March 2006): 51–55. https://doi.org/10.1177/1478271520063601015.

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Myotonic dystrophy is the most common form of muscular dystrophy in adults, with a prevalence of 1 in 8,000. It is a slowly progressive, multi-system disorder that affects skeletal muscles, the heart, gastrointestinal smooth muscle, uterine smooth muscle, the eyes, and the endocrine and central nervous systems. Myotonic dystrophy is almost always caused by an autosomal dominant gene mutation in the DMPK gene located on chromosome 19. The gene mutation is an expansion in the length of a three base-pair (triplet) repeat sequence (cytosine–thymine–guanine, or CTG) above the normal upper limit of 35 repeats. The expanded CTG repeat is classed as a ‘dynamic’ mutation because the number of repeats tends to increase in size over successive generations in myotonic dystrophy families. In general, larger CTG expansions are associated with earlier age-of-onset and more severe signs and symptoms of myotonic dystrophy. Patients with 50–100 CTG repeats may develop cataract, diabetes, grip myotonia, or mild muscle weakness in mid to late adulthood. Patients with 200–500 CTG repeats are affected earlier and more severely by facial and distal limb muscle weakness and myotonia. A CTG repeat size above 1,000 is associated with prenatal onset of disease and congenital myotonic dystrophy, which may be fatal due to respiratory failure. Feeding difficulties, muscle weakness, club foot deformity, and cognitive impairments are present in surviving infants. Although males and females are equally likely to inherit myotonic dystrophy, the very large mutations (>1,000 repeats) which result in the congenital form of myotonic dystrophy are virtually always transmitted by an affected mother. DNA tests are used to estimate repeat size and permit accurate prenatal, presymptomatic, and diagnostic genetic testing.

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Zhang, Yan, and XiongJie Yang. "Clinical Analysis of Two Cases of Myotonic Dystrophy Patients Treated with Chinese Medicine." Journal of Contemporary Medical Practice 7, no. 1 (January 31, 2025): 225–28. https://doi.org/10.53469/jcmp.2025.07(01).41.

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Myotonic dystrophy (DM) is a group of multi-systemic autosomal dominant genetic disorders characterized by muscle weakness, myotonia, and muscle atrophy. This study clinically analyzed two patients with myotonic dystrophy, both diagnosed with “Wei” disease in traditional Chinese medicine (TCM), with syndromes of liver-kidney deficiency and spleen-stomach weakness, respectively. The treatment methods included moxibustion, acupuncture at specific points, and a combination of TCM decoctions with modifications. After treatment, the patients showed improvement in their symptoms. This study provides new insights into the TCM treatment of DM.

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Kitsis, Elizabeth A., Fabreena Napier, Viral Juthani, and Howard L. Geyer. "Association of Sjögren’s syndrome with myotonic dystrophy type 1." BMJ Case Reports 12, no. 8 (August 2019): e229611. http://dx.doi.org/10.1136/bcr-2019-229611.

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A 47-year-old woman presented with sicca symptoms, polyarthralgias, polymyalgias and dysphagia. She was found to have positive antinuclear, anti-SSA-Ro and anti-SSB-La antibodies. Slit lamp exam confirmed the presence of keratoconjunctivitis sicca, and the patient was diagnosed with Sjögren’s syndrome. Three years later, she was referred for evaluation of gait instability associated with recent falls. On physical examination, the patient was found to have bilateral ptosis, percussion myotonia, distal upper and lower extremity weakness, and a steppage gait. Electromyography demonstrated electrical myotonia. Genetic testing revealed expanded CTG repeats (733 and 533) in the myotonic dystrophy type 1 (DM1) protein kinase gene, confirming the diagnosis of DM1. Dysphagia, pain and eye discomfort may occur in both Sjögren’s syndrome and DM1, and in this case, may have delayed the diagnosis of muscular dystrophy.

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Schneider-Gold, Christiane, Benedikt Schoser, Gisa Ellrichmann, Stefan Quasthoff, Frank Lehmann-Horn, and Michael Sinnreich. "Myotone Dystrophien, nicht dystrophe Myotonien und periodische Paralysen." Aktuelle Neurologie 45, no. 03 (February 23, 2018): 167–77. http://dx.doi.org/10.1055/s-0043-125352.

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ZusammenfassungIn der Behandlung der myotonen Dystrophien, nicht dystrophen Myotonien und periodischen Paralysen haben sich in den letzten Jahren einige neue Aspekte ergeben, die in der aktualisierten Leitlinie zu myotonen Dystrophien, nicht dystrophen Myotonien und periodischen Paralysen zusammenfassend dargestellt sind.Nach wie vor besteht eine europaweit nur sehr eingeschränkte Verfügbarkeit von Mexiletin, welches in Deutschland nur noch über die Auslandsapotheke aus z. B. Japan, den USA oder Kanada in einer Dosierung von 100 mg oder 200 mg bezogen werden kann, wenngleich die Wirksamkeit von Mexiletin bei myotoner Dystrophie Typ 1 in einer amerikanischen Studie erneut bestätigt wurde (Logigian et al., 2010).In einer rezenten Studie konnte gezeigt werden, dass der Carboanhydrasehemmer Dichlorphenamid sowohl bei hypokaliämischer als auch bei hyperkaliämischer periodischer Paralyse die Attackenfrequenz senkt, allerdings war der Unterschied bei der hyperkaliämischen Lähmung nicht signifikant (Sansone et al., 2016). Bei dieser Studie handelt es sich um die Kombination zweier randomisierter Untersuchungen über 9 Wochen, kombiniert mit einer einjährigen Extensionsphase, bei der alle Teilnehmer Dichlorphenamid erhielten. Die Studie wurde gegen Placebo durchgeführt; der ursprünglich geplante Vergleich mit Acetazolamid wurde abgebrochen, weil die an der Studie teilnehmenden Patienten Dichlorphenamid aufgrund subjektiv besserer Wirksamkeit vorzogen und deshalb keine Gruppe für einen Vergleich Dichlorphenamid/Acetazolamid gebildet werden konnte. Die Hauptnebenwirkungen waren Parästhesien, Nierensteinbildung und eine Verlangsamung des Denkens. Die Studie erlaubte keine Rückschlüsse auf die Beziehung zwischen Wirksamkeit und Genotyp; die häufigste Mutation war T704 M (Nav1.4) bei der hyperkaliämischen Lähmung und R528H (Cav1.1) und R1239H (Cav1.1) bei der hypokaliämischen Lähmung. Ein Patient in der hypokaliämischen Gruppe mit der Mutation pR222 W (Nav1.4) verschlechterte sich. Dichlorphenamid ist inzwischen als Keveyis in den USA im Handel. In der Europäischen Union ist Dichlorphenamid (noch) nicht zugelassen; es hat aber den Status einer „orphan drug“ und ist somit verordnungsfähig.In einer doppelblinden randomisierten placebokontrollierten Studie mit 22 Patienten mit nicht dystrophen Myotonien konnte gezeigt werden, dass Lamotrigin in einer Dosierung von 300 mg/d die myotone Symptomatik signifikant gegenüber dem Ausgangsbefund verbesserte (Anderson G et al., 2017).Eine offene Behandlungsstudie mit Ranolazin, einem Piperazinderivat, in einer Dosierung von 2 × 500 mg bei 13 Patienten mit Chloridkanalmyotonie ergab eine signifikant reduzierte EMG-Myotonie, eine nach Patientenangaben signifikant reduzierte Muskelsteifigkeit und geringer auch reduzierte Muskelschwäche und eine reduzierte Myotonie in den klinischen Tests (Arnold WD et al., 2017).

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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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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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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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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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Mankodi, Ami, and Christopher Grunseich. "Toe-extension myotonia in myotonic dystrophy type 1." Neurology 85, no. 2 (July 13, 2015): 203. http://dx.doi.org/10.1212/wnl.0000000000001734.

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Rimmer, Karen P., Sandra D. Golar, M. A. Lee, and William A. Whitelaw. "Myotonia of the Respiratory Muscles in Myotonic Dystrophy." American Review of Respiratory Disease 148, no. 4_pt_1 (October 1993): 1018–22. http://dx.doi.org/10.1164/ajrccm/148.4_pt_1.1018.

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Conravey, Allison, and Lenay Santana-Gould. "Myotonia Congenita and Myotonic Dystrophy: Surveillance and Management." Current Treatment Options in Neurology 12, no. 1 (January 2010): 16–28. http://dx.doi.org/10.1007/s11940-009-0055-z.

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Reed, Stephen M., Gerald A. Hegreberg, Warwick M. Bayly, Christopher M. Brown, Mary R. Paradis, and Roger M. Clemmons. "Progressive myotonia in foals resembling human dystrophia myotonica." Muscle & Nerve 11, no. 4 (April 1988): 291–96. http://dx.doi.org/10.1002/mus.880110403.

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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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Pfeilsticker, Beatriz Helena Miranda, Carmen Sílvia Bertuzzo, and Anamarli Nucci. "Electrophysiological evaluation in myotonic dystrophy: correlation with CTG length expansion." Arquivos de Neuro-Psiquiatria 59, no. 2A (June 2001): 186–91. http://dx.doi.org/10.1590/s0004-282x2001000200006.

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In myotonic dystrophy (MD), disease severity has been correlated with expansion of CTG repeats in chromosome 19. The aims of this study were to evaluate efficacy of electromyography in the diagnosis of MD, access the frequency and the characteristics of peripheral involvement in the disease and to verify whether the CTG repeats correlated with the electrophysiological abnormalities. Twenty-five patients and six relatives at risk of carrying the MD gene were examined. Electrical myotonia (EM) was scored. Sensory and motor conduction velocity (CV) were studied in five nerves. Leukocyte DNA analysis was done in 26 subjects. Myopathy and myotonia were found in 27 cases. EM was most frequent in muscles of hand and in tibialis anterior. No significant correlation was found between EM scores and length of CTG expansions. EM scores correlated significantly with the degree of clinical myopathy, expressed by a muscular disability scale. Peripheral neuropathy was found in eight subjects and was not restricted to those who were diabetics.

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Montagnese, Federica, and Benedikt Schoser. "Dystrophische und nicht-dystrophische Myotonien." Fortschritte der Neurologie · Psychiatrie 86, no. 09 (September 2018): 575–83. http://dx.doi.org/10.1055/a-0635-8285.

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ZusammenfassungMyotone Syndrome sind seltene Erkrankungen der Skelettmuskulatur die mit einer klinischen und elektrischen Myotonie einhergehen. Die genetischen Defekte betreffen primär oder sekundär muskuläre Ionenkanäle und führen zu einer Übererregbarkeit der muskulären Membran. Zu den dystrophischen Myotonien gehören die myotone Dystrophie Typ 1 (DM1) und die myotone Dystrophie Typ 2 (DM2). Es handelt sich bei beiden um multisystemische Erkrankungen, bei denen neben der Myotonie und dystrophischen Veränderungen der Muskulatur (z. B. Muskelatrophie, Muskelschwäche) auch eine Beteiligung verschiedener anderer Organe (Katarakt, Diabetes, Herzerkrankungen, endokrine Störungen) vorhanden ist. Zu den nicht-dystrophischen Myotonien gehören u. a. die Chlorid- und Natriumkanal-Myotonie. Bei diesen steht das Symptom Myotonie im Vordergrund und gelegentlich werden andere muskuläre Auffälligkeiten (Muskelhypertrophie, transiente Muskelschwäche) beobachtet. Die Differentialdiagnose ist oft eine Herausforderung und die zeitliche Verzögerung bis zur endgültigen Diagnosestellung weiterhin sehr lang. In dieser Übersicht werden Hauptaspekte der klinischen Symptome, der Diagnosestellung und der symptomatischen Therapie der dystrophischen und nicht-dystrophischen Myotonien dargestellt.

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Romigi, A., M. Albanese, C. Liguori, F. Placidi, M. G. Marciani, and R. Massa. "Sleep-Wake Cycle and Daytime Sleepiness in the Myotonic Dystrophies." Journal of Neurodegenerative Diseases 2013 (November 4, 2013): 1–13. http://dx.doi.org/10.1155/2013/692026.

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Myotonic dystrophy is the most common type of muscular dystrophy in adults and is characterized by progressive myopathy, myotonia, and multiorgan involvement. Two genetically distinct entities have been identified, myotonic dystrophy type 1 (DM1 or Steinert’s Disease) and myotonic dystrophy type 2 (DM2). Myotonic dystrophies are strongly associated with sleep dysfunction. Sleep disturbances in DM1 are common and include sleep-disordered breathing (SDB), periodic limb movements (PLMS), central hypersomnia, and REM sleep dysregulation (high REM density and narcoleptic-like phenotype). Interestingly, drowsiness in DM1 seems to be due to a central dysfunction of sleep-wake regulation more than SDB. To date, little is known regarding the occurrence of sleep disorders in DM2. SDB (obstructive and central apnoea), REM sleep without atonia, and restless legs syndrome have been described. Further polysomnographic, controlled studies are strongly needed, particularly in DM2, in order to clarify the role of sleep disorders in the myotonic dystrophies.

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Barchi, Robert L. "Myotonia." Neurologic Clinics 6, no. 3 (August 1988): 473–84. http://dx.doi.org/10.1016/s0733-8619(18)30855-7.

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Vlodavets, D., M. Shkolnikova, V. Bereznitskaya, Z. Romantsova, R. Ildarova, A. Monakhova, O. Shidlovskaya, et al. "MYOTONIA." Neuromuscular Disorders 29 (October 2019): S69. http://dx.doi.org/10.1016/j.nmd.2019.06.126.

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Reed, Umbertina C., Suely K. Nagahashi Marie, Mario Wilson I. Brotto, Carlos Alberto Martinez, Paulo E. Marchiori, Aron Diament, and José Antonio Levy. "Autosomal recessive nondystrophic myotonia report of a case with unusual clinical course: relato de um caso com aspectos clínicos atípicos." Arquivos de Neuro-Psiquiatria 53, no. 1 (March 1995): 114–17. http://dx.doi.org/10.1590/s0004-282x1995000100017.

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We describe the case of a girl with a probable autosomal recessive form of nondystrophic hereditary myotonia whose clinical findings are more compatible with the dominant ones mainly myotonia congenita of Thomsen or myotonia fluctuans. Besides the clinical aspects of the atypical form presented by our patient, the efficacy of the more available drugs employed for the treatment of myotonia congenita is briefly discussed .

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Benstead, Timothy J., Peter R. Camfield, and David B. King. "Treatment of Paramyotonia Congenita with Acetazolamide." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 14, no. 2 (May 1987): 156–58. http://dx.doi.org/10.1017/s0317167100026305.

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Abstract:Treatment of paramyotonia congenita with acetazolamide has been shown to reduce myotonic symptoms but severe weakness has developed in some patients leading to a recommendation not to use the drug in this disorder. We studied a patient with the characteristic clinical and electrophysiological profile of paramyotonia congenita. Myotonia was effectively treated with a very low dose of acetazolamide and no weakness developed. We conclude that acetazolamide can be a safe and effective medication in paramyotonia congenita.

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Rho, Yunjung, Jinmann Chon, Myung Chul Yoo, Ga Yang Shim, Sung Joon Chung, and Yunsoo Soh. "Acute cricopharyngeal achalasia after general anesthesia in myotonic dystrophy: A case report." Medicine 102, no. 48 (December 1, 2023): e36378. http://dx.doi.org/10.1097/md.0000000000036378.

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Rationale: Myotonic dystrophy type 1 (DM-1) is a progressive multisystem genetic disorder that causes myotonia and both distal limb and facial/neck muscle weakness by expanding the CTG repeats of the DMPK gene in chromosome 19q13.3. General anesthesia is indicated in DM-1 patients owing to their sensitivity to anesthetic drugs such as opioids, hypnotics, and neuromuscular blocking agents. Patient concerns: A 48-year-old male patient underwent a laparoscopic cholecystectomy for gallstones under general anesthesia. He experienced sudden cardiac arrest and respiratory failure the day after surgery. After a thorough review of past medical history, we recognized that 15 years prior, he had been diagnosed with classic type DM-1, but the diagnosis was not self-reported before general anesthesia. Symptoms of severe dysphagia developed subsequently. In a videofluoroscopic swallowing study (VFSS), we observed abrupt aggravation of myotonic dysphagia after general anesthesia. VFSS revealed cricopharyngeal opening dysfunction, with a remaining large residue in the pyriform sinus, resulting in a severe cricopharyngeal achalasia pattern. Diagnosis: Acute cricopharyngeal achalasia after general anesthesia. Intervention and outcome: The patient underwent a dysphagia rehabilitation program that included cricopharyngeal opening exercises and functional electrical stimulation. However, no significant improvement was observed in the cricopharyngeal achalasia in a 3-month follow-up VFSS. Lessons: Low body temperature and anesthetic medications such as opioids and hypnotic agents can induce myotonia in the cricopharyngeal muscle.

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