Annals of Indian Academy of Neurology
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Year
: 2008  |  Volume : 11  |  Issue : 1  |  Page : 20--27

Muscle channelopathies and electrophysiological approach


Ajith Cherian, Neeraj N Baheti, Abraham Kuruvilla 
 Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum - 695 011, India

Correspondence Address:
Ajith Cherian
Department of Neurology, SCTIMST, Trivandrum, Kerala
India

Myotonic syndromes and periodic paralyses are rare disorders of skeletal muscle characterized mainly by muscle stiffness or episodic attacks of weakness. Familial forms are caused by mutation in genes coding for skeletal muscle voltage ionic channels. Familial periodic paralysis and nondystrophic myotonias are disorders of skeletal muscle excitability caused by mutations in genes coding for voltage-gated ion channels. These diseases are characterized by episodic failure of motor activity due to muscle weakness (paralysis) or stiffness (myotonia). Clinical studies have identified two forms of periodic paralyses: hypokalemic periodic paralysis (hypoKPP) and hyperkalemic periodic paralysis (hyperKPP), based on changes in serum potassium levels during the attacks, and three distinct forms of myotonias: paramyotonia congenita (PC), potassium-aggravated myotonia (PAM), and myotonia congenita (MC). PC and PAM have been linked to missense mutations in the SCN4A gene, which encodes α subunit of the voltage-gated sodium channel, whereas MC is caused by mutations in the chloride channel gene (CLCN1). Exercise is known to trigger, aggravate, or relieve symptoms. Therefore, exercise can be used as a functional test in electromyography to improve the diagnosis of these muscle disorders. Abnormal changes in the compound muscle action potential can be disclosed using different exercise tests. Five electromyographic (EMG) patterns (I-V) that may be used in clinical practice as guides for molecular diagnosis are discussed.


How to cite this article:
Cherian A, Baheti NN, Kuruvilla A. Muscle channelopathies and electrophysiological approach.Ann Indian Acad Neurol 2008;11:20-27


How to cite this URL:
Cherian A, Baheti NN, Kuruvilla A. Muscle channelopathies and electrophysiological approach. Ann Indian Acad Neurol [serial online] 2008 [cited 2020 Aug 7 ];11:20-27
Available from: http://www.annalsofian.org/article.asp?issn=0972-2327;year=2008;volume=11;issue=1;spage=20;epage=27;aulast=Cherian;type=0