Myotonia

Myotonia
Myotonia
Classification and external resources
ICD-10 G71.1
ICD-9 359.2
DiseasesDB 23079
MeSH D009222

Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by the slow relaxation of the muscles after voluntary contraction or electrical stimulation. Generally, repeated effort is needed to relax the muscles, and the condition improves after the muscles have warmed up. However, prolonged, rigorous exercise may also trigger the condition. Individuals with the disorder may have trouble releasing their grip on objects or may have difficulty rising from a sitting position and a stiff, awkward gait.

Myotonia can affect all muscle groups; however, the pattern of affected muscles can vary depending on the specific disorder involved.

People suffering from disorders involving myotonia can have a life-threatening reaction to certain anaesthetics; one of these conditions occurs when the patient is under anaesthetic and is termed "Malignant hyperthermia".

Causes

It may be acquired or inherited, and is caused by an abnormality in the muscle membrane--specifically, the ion channels that control the contraction of muscle fibers. Myosin is defective in myotonia. Myotonia is a symptom commonly seen in patients with myotonic muscular dystrophy, of which two documented types and one speculated type exist, and in a group of disorders called channelopathies (hereditary diseases that are caused by mutations in the chloride, sodium or potassium ion transport channels in the muscle membrane), such as Myotonia Congenita (Congenital Myotonia) of which two types called Becker's Disease and Thomsen's Disease exist. There is also a disorder called Paramyotonia Congenita. Myotonia arises from channelopathies, and myotonic muscular dystrophy can be exacerbated by exposure to cold (and occasionally heat); by eating foods that are potassium-rich (such as bananas); with exertion, especially after long periods of inactivity; sudden surprises; and stressful situations.

Symptoms of myotonia are more frequently experienced in women during pregnancy.

Myotonia is not always a disease-related or abnormal phenomenon. Humans and other animals (such as the fainting goat) often display myotonia when placed in situations of extreme stress or fear; a resultant increase in 'fight-or-flight' hormones such as epinephrine and cortisol may cause increased muscle tension throughout the body.

See also

External links


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Look at other dictionaries:

  • myotonia — [mī΄ō tō′nē ə] n. [ MYO + TON(IC) + IA] prolonged muscular spasm, often a manifestation of certain diseases of muscles myotonic [mī΄ətän′ik] adj …   English World dictionary

  • myotonia — myotonic /muy euh ton ik/, adj. /muy euh toh nee euh/, n. Pathol. tonic muscle spasm or muscular rigidity. [1895 1900; MYO + TONIA] * * * Disorder causing difficulty relaxing contracted voluntary muscles. All or only a few may be affected.… …   Universalium

  • 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. [ …   Medical dictionary

  • myotonia — 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… …   The new mediacal dictionary

  • Myotonia congenita — Classification and external resources ICD 10 G71.1 ICD 9 359.2 …   Wikipedia

  • myotonia congenita — myotonia congenita. См. болезнь Томсена. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • myotonia congenita — myotonia con·gen·i·ta kän jen ə tə n an inherited condition that is characterized by delay in the ability to relax muscles after forceful contractions but not by wasting of muscle called also Thomsen s disease * * * tonic spasm and rigidity of… …   Medical dictionary

  • myotonia dystrophica — myotonia dys·tro·phi·ca dis träf i kə, trōf n MYOTONIC DYSTROPHY * * * myotonic dystrophy …   Medical dictionary

  • Myotonia congenita Becker — Klassifikation nach ICD 10 G71.1 Myotone Syndrome Myotonia congenita, rezessiv (Becker) …   Deutsch Wikipedia

  • Myotonia congenita — Unter Myotonie werden verschiedene Muskelerkankungen zusammengefasst, die sich durch eine krankhaft verlängerte, tonische Muskelanspannung auszeichnen. Die elektrische Aktivität des Muskel gemessen im Elektromyogramm (EMG) zeigt ein typisches… …   Deutsch Wikipedia

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