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https://www.readbyqxmd.com/read/29050397/the-antimyotonic-effect-of-lamotrigine-in-non-dystrophic-myotonias-a-double-blind-randomized-study
#1
Grete Andersen, Gitte Hedermann, Nanna Witting, Morten Duno, Henning Andersen, John Vissing
Mexiletine is the only drug with proven effect for treatment of non-dystrophic myotonia, but mexiletine is expensive, has limited availability and several side effects. There is therefore a need to identify other pharmacological compounds that can alleviate myotonia in non-dystrophic myotonias. Like mexiletine, lamotrigine is a sodium channel blocker, but unlike mexiletine, lamotrigine is available, inexpensive, and well tolerated. We investigated the potential of using lamotrigine for treatment of myotonia in patients with non-dystrophic myotonias...
September 1, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/29048924/de-novo-mutation-in-cacna1s-gene-in-a-20-year-old-man-diagnosed-with-metabolic-myopathy
#2
Masoud Edizadeh, Raheleh Vazehan, Fatemeh Javadi, Shima Dehdahsi, Mahsa Fadaee, Mehrshid Faraji Zonooz, Elham Parsimehr, Fatemeh Ahangari, Ayda Abolhassani, Zahra Kalhor, Zohreh Fattahi, Maryam Beheshtian, Ariana Kariminejad, Mohammad Reza Akbari, Hossein Najmabadi, Shahriar Nafissi
The calcium channel, voltage-dependent, L-type, alpha 1S subunit (CACNA1S) gene encodes a skeletal Ca2+ channel which is involved in calcium-dependent processes such as muscle contraction and neurotransmitter release. Mutations in this gene have been accompanied by hypo- and normokalemic periodic paralysis, thyrotoxic periodic paralysis, and susceptibility to malignant hyperthermia. We report the clinical and genetic findings in a patient diagnosed with metabolic myopathy who had episodic attacks of muscle pain and weakness but with no family background of the disease...
September 2017: Archives of Iranian Medicine
https://www.readbyqxmd.com/read/28993909/coexistence-of-clcn1-and-scn4a-mutations-in-one-family-suffering-from-myotonia
#3
Lorenzo Maggi, Sabrina Ravaglia, Alessandro Farinato, Raffaella Brugnoni, Concetta Altamura, Paola Imbrici, Diana Conte Camerino, Alessandro Padovani, Renato Mantegazza, Pia Bernasconi, Jean-François Desaphy, Massimiliano Filosto
Non-dystrophic myotonias are characterized by clinical overlap making it challenging to establish genotype-phenotype correlations. We report clinical and electrophysiological findings in a girl and her father concomitantly harbouring single heterozygous mutations in SCN4A and CLCN1 genes. Functional characterization of N1297S hNav1.4 mutant was performed by patch clamp. The patients displayed a mild phenotype, mostly resembling a sodium channel myotonia. The CLCN1 c.501C>G (p.F167L) mutation has been already described in recessive pedigrees, whereas the SCN4A c...
October 9, 2017: Neurogenetics
https://www.readbyqxmd.com/read/28940424/n1366s-mutation-of-human-skeletal-muscle-sodium-channel-causes-paramyotonia-congenita
#4
Qing Ke, Jia Ye, Siyang Tang, Jin Wang, Benyan Luo, Fang Ji, Xu Zhang, Ye Yu, Xiaoyang Cheng, Yuezhou Li
Paramyotonia congenita is an autosomal dominant skeletal muscle channelopathy caused by missense mutations in SCN4A, the gene encoding the α subunit of the human skeletal muscle voltage-gated sodium channel NaV1.4. Here, we report a three-generation family in which six members present clinical symptoms of paramyotonia congenita characterized by a marked worsening of myotonia by cold and by the presence of clear episodes of paralysis. We identified a novel mutation in SCN4A (Asn-1366-Ser, N1366S) in all patients in the family but not in healthy relatives or in 500 normal control subjects...
September 20, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28939973/sodium-channelopathies-of-skeletal-muscle
#5
Stephen C Cannon
The NaV1.4 sodium channel is highly expressed in skeletal muscle, where it carries almost all of the inward Na(+) current that generates the action potential, but is not present at significant levels in other tissues. Consequently, mutations of SCN4A encoding NaV1.4 produce pure skeletal muscle phenotypes that now include six allelic disorders: sodium channel myotonia, paramyotonia congenita, hyperkalemic periodic paralysis, hypokalemic periodic paralysis, congenital myasthenia, and congenital myopathy with hypotonia...
September 23, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/28939972/effects-of-benzothiazolamines-on-voltage-gated-sodium-channels
#6
Alessandro Farinato, Concetta Altamura, Jean-François Desaphy
Benzothiazole is a versatile fused heterocycle that aroused much interest in drug discovery as anticonvulsant, neuroprotective, analgesic, anti-inflammatory, antimicrobial, and anticancer. Two benzothiazolamines, riluzole and lubeluzole, are known blockers of voltage-gated sodium (Nav) channels. Riluzole is clinically used as a neuroprotectant in amyotrophic lateral sclerosis. Inhibition of Nav channels by riluzole is voltage-dependent due to preferential binding to inactivated sodium channels. Yet the drug exerts little use-dependent block, probably because it lacks protonable amine...
September 23, 2017: Handbook of Experimental Pharmacology
https://www.readbyqxmd.com/read/28877545/in-vivo-assessment-of-muscle-membrane-properties-in-the-sodium-channel-myotonias
#7
S Veronica Tan, Werner J Z'Graggen, Michael G Hanna, Hugh Bostock
INTRODUCTION: The gain-of-function mutations that underlie sodium channel myotonia (SCM) and paramyotonia congenital (PMC) produce differing clinical phenotypes. We used muscle velocity recovery cycles (MVRCs) to investigate membrane properties. METHODS: MVRCs and responses to trains of stimuli were compared in patients with SCM (n = 9), PMC (n = 8), and normal controls (n = 26). RESULTS: The muscle relative refractory period was reduced in SCM, consistent with faster recovery of the mutant sodium channels from inactivation...
September 6, 2017: Muscle & Nerve
https://www.readbyqxmd.com/read/28833464/inhibiting-persistent-inward-sodium-currents-prevents-myotonia
#8
Ahmed A Hawash, Andrew A Voss, Mark M Rich
OBJECTIVE: Patients with myotonia congenita have muscle hyperexcitability due to loss-of-function mutations in the ClC-1 chloride channel in skeletal muscle, which causes involuntary firing of muscle action potentials (myotonia), producing muscle stiffness. The excitatory events that trigger myotonic action potentials in the absence of stabilizing ClC-1 current are not fully understood. Our goal was to identify currents that trigger spontaneous firing of muscle in the setting of reduced ClC-1 current...
September 2017: Annals of Neurology
https://www.readbyqxmd.com/read/28810563/dystrophia-myotonica-type-1-presenting-with-dysarthria-a-case-report-and-literature-review
#9
Chunrong Li, Xiaoling Zhang, Chunkui Zhou, Lijun Zhu, Kangding Liu, Shaokuan Fang
Dystrophia myotonica (DM) type 1 is an autosomal dominant disorder, caused by a trinucleotide CTG repeat expansion in the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene (chromosome 19q13.3). The disorder affects different organ systems, including the skeletal muscles, ocular lens, lungs, heart and gastrointestinal tract, as well as the endocrine and central nervous systems. The skeletal muscles are most frequently involved, whereby the disorder manifests as myotonia, muscle weakness and amyotrophy...
August 2017: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28782311/myotonic-dystrophy-type-1-clinical-electrophysiological-and-molecular-characterization-experience-at-tertiary-care-centre
#10
Satish Khadilkar, Kamlesh Jagiasi, Jayendra Yadav, Sushant V Chavan, Girish Soni, Bhagyadhan Patel
OBJECTIVE: Myotonic dystrophy type 1 (DM1) is the most common myotonic disorder. Molecular genetic testing of the Dystrophia Myotonica-Protein Kinase DMPK gene to detect expansion of CTG repeats is confirmatory. TP-PCR (Triplet Primed-Polymerase Chain Reaction) is rapid and effective screening for the CTG repeat expansions in myotonic dystrophy. Indian data regarding clinical and genetic evaluation of DM1 are sparse. MATERIAL AND METHODS: This was a prospective observational study at a tertiary neurology centre...
June 2017: Journal of the Association of Physicians of India
https://www.readbyqxmd.com/read/28715597/the-proposal-of-a-clinical-protocol-to-assess-central-and-peripheral-fatigue-in-myotonic-dystrophy-type-1
#11
S Baldanzi, G Ricci, M Bottari, L Chico, C Simoncini, G Siciliano
DM1 is an autosomal-dominant disorder characterized by muscle weakness, myotonia, and multisystemic involvement. According to current literature fatigue and daytime sleepiness are among the main symptoms of DM1. Oxidative stress has been proposed to be one of the pathogenic factors of fatigue consequent to DM1. In this study, we investigated the dimensions of experienced fatigue and  physiological fatigue in a sample of 26 DM1 patients (17 males, 9 females, mean age 41.6 years, SD±12.7); experienced fatigue has been studied through Fatigue Severity Scale (FSS), and physiological fatigue was measured through an intermittent incremental exercise of the forearm muscles using a myometer; oxidative stress balance markers trend during aerobic exercise test have been collected...
July 1, 2017: Archives Italiennes de Biologie
https://www.readbyqxmd.com/read/28710329/open-label-trial-of-ranolazine-for-the-treatment-of-myotonia-congenita
#12
W David Arnold, David Kline, Alan Sanderson, Ahmed A Hawash, Amy Bartlett, Kevin R Novak, Mark M Rich, John T Kissel
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...
August 15, 2017: Neurology
https://www.readbyqxmd.com/read/28706458/electrophysiological-characteristics-of-r47w-and-a298t-mutations-in-clc-1-of-myotonia-congenita-patients-and-evaluation-of-clinical-features
#13
Hyung Jin Chin, Chan Hyeong Kim, Kotdaji Ha, Jin Hong Shin, Dae-Seong Kim, Insuk So
Myotonia congenita (MC) is a genetic disease that displays impaired relaxation of skeletal muscle and muscle hypertrophy. This disease is mainly caused by mutations of CLCN1 that encodes human skeletal muscle chloride channel (CLC-1). CLC-1 is a voltage gated chloride channel that activates upon depolarizing potentials and play a major role in stabilization of resting membrane potentials in skeletal muscle. In this study, we report 4 unrelated Korean patients diagnosed with myotonia congenita and their clinical features...
July 2017: Korean Journal of Physiology & Pharmacology
https://www.readbyqxmd.com/read/28687444/long-term-follow-up-for-patients-with-nonprogressive-epilepsia-partialis-continua-in-a-single-center-in-china
#14
Song Yan, Yan-Chun Deng, Xiao-Li Wang, Meng-Meng Hu, Yong-Hong Liu, Lei Ma
Epilepsia partialis continua (EPC) is a rare variant of epilepsy. Cases from China are rare. We present a case series of seven patients to analyze its clinical features, imagining findings, etiology, drug use, and long-term outcome in a single epilepsy center. We made assessments of drug effects twice (Stage I - when they left our hospital; Stage II in March 2017 - by telephone interviews to rate their long-term outcome). The mean duration of the second follow-up was 4.8years. Of the seven patients, four patients characterized motor and sensory EPC and three motor EPC...
October 2017: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
https://www.readbyqxmd.com/read/28662944/skeletal-muscle-channelopathies-rare-disorders-with-common-pediatric-symptoms
#15
Emma Matthews, Arpana Silwal, Richa Sud, Michael G Hanna, Adnan Y Manzur, Francesco Muntoni, Pinki Munot
OBJECTIVE: To ascertain the presenting symptoms of children with skeletal muscle channelopathies to promote early diagnosis and treatment. STUDY DESIGN: Retrospective case review of 38 children with a skeletal muscle channelopathy attending the specialist pediatric neuromuscular service at Great Ormond Street Hospital over a 15-year period. RESULTS: Gait disorder and leg cramps are a frequent presentation of myotonic disorders (19 of 29). Strabismus or extraocular myotonia (9 of 19) and respiratory and/or bulbar symptoms (11 of 19) are common among those with sodium channelopathy...
September 2017: Journal of Pediatrics
https://www.readbyqxmd.com/read/28660733/prospective-measurement-of-quality-of-life-in-myotonic-dystrophy-type-1
#16
S Peric, C Heatwole, E Durovic, A Kacar, A Nikolic, I Basta, A Marjanovic, Z Stevic, D Lavrnic, V Rakocevic Stojanovic
INTRODUCTION: Generic patient reported outcome measures have had varied success in tracking QoL in myotonic dystrophy type 1 (DM1). AIM: To analyze changes of Individualized Neuromuscular Quality of Life questionnaire (INQoL) scores in clinic patients with DM1 over a 6-year period. METHOD: Patients completed the INQoL at baseline and after a 6-year period through their attendance in a neurology outpatient clinic. Severity of muscular involvement in DM1 was analyzed using the Muscular Impairment Rating Scale (MIRS)...
June 28, 2017: Acta Neurologica Scandinavica
https://www.readbyqxmd.com/read/28561926/quantitative-sonographic-assessment-of-myotonia
#17
Alon Abraham, Ari Breiner, Carolina Barnett, Vera Bril, Hans D Katzberg
INTRODUCTION: The goal of this study was to explore ultrasound imaging for qualitative and quantitative assessment of myotonia. METHODS: 16 patients with myotonia and 16 controls underwent sonographic evaluation of the thenar eminence muscles to assess the relaxation time after muscle percussion. RESULTS: The mean time for complete muscle relaxation in patients with myotonia was longer than that of controls. A cut-off of >0.9 seconds for myotonia detection had a sensitivity of 88% and a specificity of 100%...
May 31, 2017: Muscle & Nerve
https://www.readbyqxmd.com/read/28557061/classification-of-involuntary-movements-in-dogs-myoclonus-and-myotonia
#18
REVIEW
M Lowrie, L Garosi
Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one hand, a classification system is required that is clinically useful to aid in guiding diagnosis and treatment. On the other hand, there is need for a system that organizes current knowledge regarding biological mechanisms to guide scientific research. These 2 needs are distinct, making it challenging to develop a robust classification system suitable for all purposes...
July 2017: Journal of Veterinary Internal Medicine
https://www.readbyqxmd.com/read/28552867/an-unusual-case-of-sodium-channel-myotonia-with-transient-weakness-upon-initiating-movements-which-is-characteristic-in-becker-disease
#19
Junpei Yamamoto, Keiichi Hokkoku, Yuki Hatanaka, Shunichi Sakoda, Jun-Hui Yuan, Masahiro Sonoo
We reported a 32-year-old man who was a sporadic case of myotonic syndrome with muscle stiffness or transient weakness of limbs upon initiating movements after rest. On examination, he showed painless myotonia with warm-up phenomenon, Hercules-like hypertrophic musculature and myotonic discharges in EMG. The clinical findings resembled to those of Becker disease rather than Thomsen disease. But electrodiagnosis suggested sodium channel myotonia instead of chloride channelopathy. Genetic testing detected a novel missense mutation (p...
June 28, 2017: Rinshō Shinkeigaku, Clinical Neurology
https://www.readbyqxmd.com/read/28550479/biomolecular-diagnosis-of-myotonic-dystrophy-type-2-a-challenging-approach
#20
REVIEW
Giovanni Meola, Fiammetta Biasini, Rea Valaperta, Elena Costa, Rosanna Cardani
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are the most common adult form of muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia, and multiorgan involvement. The onset and symptoms of the myotonic dystrophies are diverse, complicating their diagnoses and limiting a comprehensive approach to their clinical care. Diagnostic delay in DM2 is due not only to the heterogeneous phenotype and the aspecific onset but also to the unfamiliarity with the disorder by most clinicians...
August 2017: Journal of Neurology
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