Periodic limb movements during sleep (PLMS)
Periodic limb movements in sleep (PLMS, formerly known as nocturnal myoclonus) are uncontrollable brief jerks (0.5 to 5.0 seconds in duration) of the limbs seen during sleep (1).
- typically these recurrent jerky movements occur at 20-40 second intervals
- frequently seen in toes, feet, and legs than in arms
- associated with transient arousal or awakening from sleep
- the patient is usually unaware of any limb movement or sleep disruption
- seen in around 80-90% of patients with RLS but is not specific for RLS (1)
- may be associated with other sleep disorders (sleep apnoea and narcolepsy) or certain medications (SSRI type antidepressants such as fluoxetine, sertraline) (1,2,3)
- other associations include iron or folate deficiency, renal disease, peripheral neuropathy, Parkinsonism, or spinal disorders, and may be exacerbated by caffeine, or neuroleptic medications
- overall prevalence is about 6% but increases with age and the condition may occur in up to 30% of people over 50y (4)
- symptoms may respond to increased exercise or reduced caffeine intake, but some individuals with excessive daytime sleepiness benefit from drug treatment such as dopamine agonists (eg, pramipexole), gabapentin, or pregabalin (4)
Periodic limb movement syndrome and excessive daytime sleepiness
- periodic limb movements during sleep are repetitive, involuntary limb movements (nocturnal myoclonus) that cause sleep fragmentation (4)
Periodic limb movements during wakefulness (PLMA) may be seen in individuals of any age (2) and has been recognized as a sensitive and specific marker for RLS (3)
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