Periodic limb movements

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By Pasquale Montagna MD

Periodic limb movements in sleep are also known as or subsume Nocturnal myoclonus. -ed.

Periodic limb movements in sleep consist of flexion movements at the ankles, knees and hips, and sometimes the arms recurring every 5 to 90 seconds, especially during light NREM sleep stages. Though an almost obligate accompaniment of the restless legs syndrome and frequent association of various neurologic and physical diseases, they are, however, also widely prevalent among the general population. In this recently updated clinical summary, Dr. Giovanni Rizzo and Professor Pietro Cortelli examine the clinical significance of periodic limb movements in sleep and the recent advances in understanding the pathophysiology of this disorder. They review the treatment options now available, emphasizing that among the different therapeutic strategies, dopaminergic agents in particular have been shown effective in controlled trials. Finally, they discuss the possible role of periodic limb movement disorder as a cardiovascular risk.

Key Points

  • Periodic limb movements are repetitive flexion movements of the toes, ankles, knees, and hips, sometimes the upper limbs too, lasting from 0.5 to 5 seconds that recur primarily in stage 1 and stage 2 of sleep with a periodicity of about every 5 to 90 seconds.
  • Periodic limb movements may be associated with no EEG changes or with EEG evidence of arousal, and are preceded and associated with autonomic activation.
  • Periodic limb movements in sleep tend to occur more frequently in the elderly population, and have been reported associated with several other medical conditions, but are especially frequent in restless legs syndrome.
  • Periodic limb movement disorder is diagnosed when movements occur at a rate of more than 5 per hour in children or 15 per hour in adults.
  • Periodic limb movements in sleep respond to dopaminergic treatment.