- Nocturnal myoclonus
Nocturnal myoclonus, also called Periodic Limb Movement Disorder (PLMD), is a
sleep disorderwhere the patient moves limbs involuntarily during sleep and has symptoms or problems related to the movement. If the patient moves limbs during sleep but there are no consequences, it is simply called periodic limb movements of sleep (PLMS). Not all patients with PLMS have PLMD (in fact, most people with PLMS do not have a disorder requiring any treatment).
PLMS is diagnosed with the aid of a
polysomnogramor PSG. PLMD is diagnosed by first finding PLMS on a PSG, then integrating that information with a detailed history from the patient and/or bed partner. PLMS can range from a small amount of movement in the ankles and toes, to wild flailing of all four limbs. These movements, which are more common in the legs than arms, occur for between 0.5 and 5 seconds, recurring at intervals of 5 to 90 seconds. A formal diagnosis of PLMS requires three periods during the night, lasting from a few minutes to an hour or more, each containing at least 30 movements followed by partial arousal or awakening.
PLMS can cause
insomniaand daytime sleepiness. The incidence of this disorder increases with age. It is estimated to occur in 5% of people age 30 to 50 and in 44% of people over the age of 65 (which means it is a normal observation in most individuals). As many as 12.2% of patients suffering from insomnia and 3.5% of patients suffering from excessive daytime sleepiness may experience PLMS.
PLMS is related to
restless leg syndrome(RLS) in that 80% of people with RLS also have PLMS. However, most people with PLMS do not experience RLS.Fact|date=March 2008
PLMS has made its way into popular culture, being referred to as "jimmy legs" and "jimmy arms" in an episode of the
televisionsitcom " Seinfeld", and has been known to cause couples to sleep in separate beds. In both examples, one subject suffers from PLMS severely enough to disturb the sleep of the other subject.
Nocturnal myoclonus is treated by medications aimed at reducing or eliminating the leg jerks or the arousals. Non-
ergotderived dopaminergic drugs ( pramipexoleand ropinirole) are preferred. Other dopaminergic agents such as co-careldopa, co-beneldopa, pergolide, or lisuridemay also be used. These drugs decrease or eliminate both the leg jerks and the arousals. These medications are also successful for the treatment of RLS restless leg syndrome.
In one study, co-careldopa was superior to
dextropropoxyphenein decreasing the number of leg kicks and the number of arousals per hour of sleep. However, co-careldopa and, to a lesser extent, pergolide may shift the leg movements from the nighttime to the daytime.
Clonazepam, (Klonopin), in doses from 2 to 8 mg at bedtime, has been shown to significantly reduce leg kicks in a patient who had nocturnal myoclonus to the degree that leg and knee pain persisted throughout the next day.
PLMD can be caused by a lack of calcium and/or iron. Taking calcium or calcium-magnesium supplements combined with iron supplements consistently for a week will reduce or eliminate symptoms in many people without the need for medication.
* Ancoli-Israel S, Kripke DF, Klauber MR, Mason WJ, Fell R, Kaplan O. Periodic limb movements in sleep in community-dwelling elderly. Sleep, 1991;14(6):496-500.
* [http://sleep.health.am/sleep/more/periodic-limb-movements-in-sleep/ Periodic Limb Movements in Sleep] Am I Res Crit Care Med. 1998;157:858-865.
* Kaplan PW, Allen RP, Buchholz DW, Walters JK. A double-blind, placebo-controlled study of the treatment of periodic limb movements in sleep using carbidopa/levidopa and propoxyphene. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&defaultField=Title+Word&term=Sleep%5Bjour%5D+AND+16%5Bvolume%5D+AND+717%5Bpage%5D+AND+1993%5Bpdat%5D+AND+Kaplan+PW%5Bauth%5D Sleep. 1993;16(8):717-723.]
* http://www.absm.org/Diplomates/listing.htm - A worldwide listing of doctors certified by the American Board of Sleep Medicine
* http://www.stanford.edu/~dement/plmd.html Information from sleep research pioneer
William C. Dement
* http://www.seinfeldscripts.com/TheMoney.html The Money, a Seinfeld Episode in which Kramer describes his girlfriend having "the Jimmy Legs"
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