myotonia

Delayed relaxation of a muscle after a strong contraction, or prolonged contraction after mechanical stimulation (as by percussion) or brief electrical stimulation; due to abnormality of the muscle membrane, specifically the ion channels. [myo- + G. tonos, tension, stretching]

- m. acquisita acquired m. following exposure to certain toxins.

- m. atrophica SYN: myotonic dystrophy.

- m. congenita [MIM*160800] an uncommon muscle disorder, with onset in infancy or early childhood, characterized by muscle hypertrophy, m., and a nonprogressive course; autosomal dominant inheritance; caused by mutations in the skeletal muscle chloride channel gene (CLCN1) on chromosome 7q. SYN: Thomsen disease.

- m. dystrophica SYN: myotonic dystrophy.

- m. neonatorum SYN: neonatal tetany.

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myo·to·nia .mī-ə-'tō-nē-ə n tonic spasm of one or more muscles also a condition characterized by such spasms

myo·ton·ic -'tän-ik adj

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n.

a disorder of the muscle fibres that results in abnormally prolonged contractions. The patient has difficulty in relaxing a movement (e.g. his grip) after any vigorous effort. It is a feature of a hereditary condition starting in infancy or early childhood (myotonia congenita) and of a form of muscular dystrophy (dystrophia myotonica).

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myo·to·nia (mi″o-toґne-ə) [myo- + ton- + -ia] dystonia involving increased muscular irritability and contractility with decreased power of relaxation; cf. tetanus (def. 2). myotonic adj