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Author Cherian, Ajith ♦ Baheti, N. N. ♦ Kuruvilla, A.
Source Sree Chitra Tirunal Institute for Medical Sciences & Technology
Content type Text
Publisher Annals of Indian Academy of Neurology
File Format PDF
Language English
Subject Domain (in DDC) Technology ♦ Medicine & health ♦ Diseases
Subject Domain (in MeSH) Nervous System Diseases ♦ Diseases ♦ Musculoskeletal and Neural Physiological Phenomena ♦ Biological Sciences
Subject Keyword Neurology
Abstract 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 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.
Education Level UG and PG
Learning Resource Type Article
Educational Framework Medical Council of India (MCI)
Journal ANNALS OF INDIAN ACADEMY OF NEUROLOGY
Volume Number 11
Issue Number 1
Page Count 8
Starting Page 20
Ending Page 27