Periodic limb movements of sleep (PLMS) is one of the sleep disorders that may cause disruptive movement of your legs, much like restless legs syndrome (RLS).
Periodic limb movements of sleep (PLMS) consists of sudden jerking movements of the legs which occur involuntarily during sleep and which the affected individual may remain unaware. It may involve kicking, twitching, or extension of the legs. It tends to increase with age and often accompanies restless legs syndrome (RLS). If PLMS causes excessive daytime sleepiness it may be termed periodic limb movement disorder (PLMD).
Diagnosis of PLMS
The gold standard for diagnosis of PLMS is a sleep study called a polysomnogram. As part of this study, superficial electrodes are placed on the legs and sometimes even the arms. These are able to detect any muscle contraction or movements.
In individuals with PLMS, there will be repetitive movements (at least four in a row) that may last from 1/2 second to 5 seconds. If these movements occur more than 15 times per hour in adults or 5 times per hour in children this is abnormal. If the movements cannot be explained by another disorder, PLMS may be the likely diagnosis. Again, if the movements lead to sleep disruption and excessive daytime sleepiness, it is called PLMD.
Treatment of PLMS
In general, it is not necessary to treat PLMS if the person affected does not have any complaints of sleep disruption. If it causes partial or total arousal from sleep, contributing to insomnia, then treatment can be considered. Also, if the movements are disruptive to a bed partner, it may also be desirable to get them under control.
Prescription medications can be effective in treating PLMS. Many of the drugs used to treat RLS are also helpful. These may include benzodiazepines, Mirapex (generic name pramipexole), and Requip (generic name ropinirole).
If your leg movements are disruptive to you at night, you should make an appointment to see a sleep specialist and have your condition properly evaluated.
American Academy of Sleep Medicine. International classification of sleep disorders. 2nd ed. 2005.
Lesage, S. et al. "The restless legs syndrome and periodic limb movement disorder: a review of management." Semin Neurol. 2004;24:249.