Twitches
TWITCHES
Twitches are brief, sudden, and fine contractions caused by electrical impulses that stimulate muscle fiber activity. Some twitches are under voluntary control, but most are involuntary. Twitches have been called muscle jerks, spasms, and fasciculations, and these terms are often used interchangeably.
Fibrillation is a contraction of a single muscle fiber. It occurs when the muscle fiber loses electrical stimulation from the nervous system. A fibrillation is not visible through the skin. This spontaneous activity often goes unnoticed and it is usually harmless. In rare instances it can be associated with inflammatory diseases of the muscle, such as polymyositis.
Fasciculation, a contraction of a group of muscle fibers that makes up a motor unit, is caused by nerve irritability. Fasciculation is seen in many older adults and most often involves the muscles of the thighs, calves, or hands. It can be chronic, lasting for days, weeks, or even years without any progression or evidence of underlying disease. When fasciculation is associated with muscle weakness or wasting, the likelihood of an underlying problem with the neuromuscular system—such as amyotrophic lateral sclerosis— increases.
Myoclonus is a rapid, brief contraction of either a proximal or a distal muscle in a nonrhythmic manner that results in movement of a body part. The most common type of myoclonus occurs in people as they are drifting off to sleep. The presence of this type of myoclonus does not imply disease. Myoclonus can be inherited in families or occur spontaneously in otherwise healthy subjects. More generalized myoclonus can occur in patients with diseases such as epilepsy or certain rare neurodegenerative disorders such as Creutzfeldt-Jakob disease. Myoclonic jerking can accompany any severe metabolic disturbance due to respiratory disease, chronic kidney failure, liver failure, or electrolyte disturbances. It can be seen in alcohol and drug withdrawal, or follow severe brain damage due to lack of oxygen to the brain. Myoclonus can be very resistant to treatment, although it may respond to treatment with certain anticonvulsant drugs like valproic acid or to a tranquilizer like clonazepam.
Restless leg syndrome is characterized by numbness and tingling of the calves. This sensation is difficult to describe, but it often causes the irresistible urge to move the legs. The symptom occurs most frequently in the evening, and it can cause significant sleep disturbance when severe. It seems to be aggravated by sleep deprivation or stress. Restless leg syndrome overlaps with a disorder known as periodic leg movements or nocturnal myoclonus. Periodic leg movements can involve the whole leg or smaller portions. The person is usually unaware of these movements, and often sleeps through them. There is an association between both disorders and increasing age, although the exact mechanism is not well understood. Medical treatments that have been tried include medications used for Parkinson’s disease, opiates, and tranquilizers.
Philip E. Lee B. Lynn Beattie
See also Deconditioning; Sarcopenia.
BIBLIOGRAPHY
Alpers, B. J., and Mancall, E. L. Essentials of the Neurological Examination. Philadelphia, PA: F. A. Davis, 1971. Pages 68–69.
Bliwise, D. L. ‘‘Sleep Disorders.’’ In Oxford Textbook of Geriatric Medicine, 2d ed. New York: Oxford Medical Publications, 2000. Pages 754–756.
Brown , D. D., and DeGown, R. L. Diagnostic Examination. Edited by Richard L. Degowin. Toronto, Canada: Collier Macmillan Canada, 1981. Pages 794–795.
Eisen, A. ‘‘Motor Neurone Disease (Amyotrophic Lateral Sclerosis).’’ In Oxford Textbook of Geriatric Medicine, 2d ed. New York: Oxford Medical Publications, 2000. Pages 791–792.
Fauci A. S., et al. Harrison’s Principles of Internal Medicine. 14th ed. New York: McGraw-Hill, 1998. Pages 114–2279.
Periodic Paralysis Association. ‘‘The PPA Online.’’ www.periodicparalysis.org
Cite this article
Pick a style below, and copy the text for your bibliography.
-
MLA
-
Chicago
-
APA
"Twitches." Encyclopedia of Aging. . Encyclopedia.com. 23 Feb. 2019 <https://www.encyclopedia.com>.
"Twitches." Encyclopedia of Aging. . Encyclopedia.com. (February 23, 2019). https://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/twitches
"Twitches." Encyclopedia of Aging. . Retrieved February 23, 2019 from Encyclopedia.com: https://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/twitches
Citation styles
Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).
Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:
Modern Language Association
The Chicago Manual of Style
http://www.chicagomanualofstyle.org/tools_citationguide.html
American Psychological Association
Notes:
- Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
- In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.