Periodic Limb Movement Disorder Clinical Presentation

Updated: Aug 03, 2021
  • Author: Deepak K Gupta, MD; Chief Editor: Selim R Benbadis, MD  more...
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Periodic limb movement disorder (PLMD) is characterized by periodic episodes of repetitive limb movements during sleep, which most often occur in the lower extremities. These movements may cause awakening during the night resulting in excessive daytime sleepiness. Often, the presenting complaint is poor sleep or unexplained insomnia and daytime somnolence. [11] Researchers report that sleep changes induced by periodic limb movements during sleep are associated with decreased physical and psychological fitness on awakening. [12]

Leg movements associated with PLMD are stereotyped and involve one or both limbs. The movement simulates triple flexion with leg flexion, ankle dorsiflexion, and great toe extension; it lasts approximately 2 seconds and thus is not consistent with the rapid jerk that defines true myoclonus. The periodicity ranges from 20 to 40 seconds with a variable duration. The movements are said to occur mainly in non-REM sleep.

Occasionally, a bed partner may provide the history of limb movements.

Nozawa et al studied arousal index and movement index in PLMD and noted that the sleep-wake disorders associated with periodic limb movement relate to threshold of awakening. [13]

Growing evidence suggests a link between restless legs syndrome (RLS) and PLMD. Picchietti et al provide evidence supporting the concept that PLMD may be a marker for an RLS genotype. [14]

The patient history may include ADHD. Walters et al provide an association between ADHD and sleep movement disorders including PLMD. [15]  There also appears to be a high prevalence of periodic limb movements of sleep in children with Down syndrome. [16]

PLMD and epilepsy are both common at the population level, however, little research has been done to establish the prevalence of periodic limb movements during sleep in people with a history of epilepsy. A few studies regarding this association have been published, though most did not adjust for potential confounding factors. Thus, further studies are warranted to determine the prevalence of PLMD in patients with a diagnosis of epilepsy. [17]

RLS and periodic limb movements during sleep are also common in patients with a history of spinal cord injury. [18]

While some patients with increased periodic limb movements during sleep may have an underlying etiology, it is important to recognize that these movements are not always indicative of a medical condition and have been shown to occur in up to 7.7% of healthy children. [19]