Flecainide-Responsive Myotonia Permanens With SNEL Onset: A New Case and Literature Review

Portaro, Simona; Rodolico, Carmelo; Sinicropi, S.; Musumeci, Olimpia; Valenzise, Mariella; Toscano, Antonio

doi:10.1542/peds.2015-3289

Cited by 25 publications

(20 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A severe form of life-threatening infantile SCN4A myotonia affecting the larynx and respiratory muscles has been reported in a handful of cases and is considered very rare (23)(24)(25)(26)(27). Our cohort indicates myotonia of these muscles is actually very common in children carrying SCN4A mutations although the severity clearly varies.…”

Section: Discussionmentioning

confidence: 99%

Skeletal Muscle Channelopathies: Rare Disorders with Common Pediatric Symptoms

Matthews

Silwal

Sud³

et al. 2017

The Journal of Pediatrics

View full text Add to dashboard Cite

Children with skeletal muscle channelopathies frequently display symptoms that are uncommon in adult disease. Any child presenting with abnormal gait, leg cramps, or strabismus, especially if intermittent, should prompt examination for myotonia. Those with sodium channel disease should be monitored for respiratory or bulbar complications. Neonatal hypotonia can herald periodic paralysis. Early diagnosis is essential for children to reach their full educational potential.

show abstract

Section: Discussionmentioning

confidence: 99%

Skeletal Muscle Channelopathies: Rare Disorders with Common Pediatric Symptoms

Matthews

Silwal

Sud³

et al. 2017

The Journal of Pediatrics

View full text Add to dashboard Cite

show abstract

“…The clinical features of dominant SCM are not significantly cold-sensitive and do not significantly decrease the compound motor action potential in an EMG test. SCM can manifest as paramyotonia, potassium-aggravated myotonia, myotonia permanens, acetazolamide-responsive myotonia, painful myotonia and severe neonatal episodic laryngospasm [4]. Patients with SCM may sometimes present with exercise-induced, delayed-onset myotonia or acetazolamide-responsive myotonia [5].…”

Section: Introductionmentioning

confidence: 99%

Changes of Resurgent Na+ Currents in the Nav1.4 Channel Resulting from an SCN4A Mutation Contributing to Sodium Channel Myotonia

Huang

Lai

Lin

et al. 2020

IJMS

View full text Add to dashboard Cite

Myotonia congenita (MC) is a rare disorder characterized by stiffness and weakness of the limb and trunk muscles. Mutations in the SCN4A gene encoding the alpha-subunit of the voltage-gated sodium channel Nav1.4 have been reported to be responsible for sodium channel myotonia (SCM). The Nav1.4 channel is expressed in skeletal muscles, and its related channelopathies affect skeletal muscle excitability, which can manifest as SCM, paramyotonia and periodic paralysis. In this study, the missense mutation p.V445M was identified in two individual families with MC. To determine the functional consequences of having a mutated Nav1.4 channel, whole-cell patch-clamp recording of transfected Chinese hamster ovary cells was performed. Evaluation of the transient Na+ current found that a hyperpolarizing shift occurs at both the activation and inactivation curves with an increase of the window currents in the mutant channels. The Nav1.4 channel’s co-expression with the Navβ4 peptide can generate resurgent Na+ currents at repolarization following a depolarization. The magnitude of the resurgent currents is higher in the mutant than in the wild-type (WT) channel. Although the decay kinetics are comparable between the mutant and WT channels, the time to the peak of resurgent Na+ currents in the mutant channel is significantly protracted compared with that in the WT channel. These findings suggest that the p.V445M mutation in the Nav1.4 channel results in an increase of both sustained and resurgent Na+ currents, which may contribute to hyperexcitability with repetitive firing and is likely to facilitate recurrent myotonia in SCM patients.

show abstract

“…Neben der bereits erwähnten Paramyotonia congenita (PMC) unterscheidet man die Kalium-aggravierte Myotonie (Potassium aggravated myotonia = PAM) und den extrem seltenen episodischen Laryngospasmus (severe neonatal episodic laryngospasm = SNEL). Diese letztgenannte Form tritt bei Neugeborenen auf und ist durch eine schwere Hypotonie mit episodischen Laryngospasmen und resultierender Apnoe charakterisiert [9]. Die muskuläre Isoform des Natriumionenkanals besteht aus dem Heterodimer Na v 1.4, das aus einer alpha-und einer beta-Untereinheit besteht.…”

Section: Nicht-dystrophische Myotonienunclassified

Dystrophische und nicht-dystrophische Myotonien

Montagnese¹,

Schöser²

2018

Fortschr Neurol Psychiatr

View full text Add to dashboard Cite

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.

show abstract

Flecainide-Responsive Myotonia Permanens With SNEL Onset: A New Case and Literature Review

Cited by 25 publications

References 24 publications

Skeletal Muscle Channelopathies: Rare Disorders with Common Pediatric Symptoms

Skeletal Muscle Channelopathies: Rare Disorders with Common Pediatric Symptoms

Changes of Resurgent Na+ Currents in the Nav1.4 Channel Resulting from an SCN4A Mutation Contributing to Sodium Channel Myotonia

Dystrophische und nicht-dystrophische Myotonien

Contact Info

Product

Resources

About