Periodic limb movements of sleep are repetitive limb movements (mostly of the legs), occurring mainly during non-rapid eye movement (non-REM) sleep; they are characterised by dorsiflexion of the toes and ankles and occasionally flexion of the hip and knee.
Periodic limb movement disorder may be diagnosed when the periodic limb movement of sleep index (PLMS-I; the number of periodic limb movements per hour of sleep) is >15 and results in clinical sleep disturbance. The diagnosis is confirmed by polysomnography, and other causes of sleep-wake disturbance must be excluded.
PLMS may arise in normal individuals, and their clinical significance in terms of sleep disturbance and excessive daytime sleepiness is controversial.
May be either primary (idiopathic) or secondary. Secondary periodic limb movement disorder (PLMD) may occur in restless legs syndrome, obstructive sleep apnoea syndrome, REM sleep behaviour disorder (RBD), narcolepsy, congestive heart failure, essential hypertension, end-stage renal disease, spinal cord injury, syringomyelia, alcohol dependence, Parkinson's disease, and Tourette's syndrome.
May be related to intake of medications including lithium, tricyclic antidepressants, and selective serotonin-reuptake inhibitors.
There is no evidence for treatment of primary PLMD. Treatment is traditionally with dopamine agonists, benzodiazepines, and opiates.
Periodic limb movements of sleep (PLMS) are characterised as repetitive limb movements (mostly of the legs) arising mainly during non-rapid eye movement (non-REM) sleep. Periodic limb movement disorder (PLMD) may be diagnosed when the frequency of periodic limb movements of sleep is >15/hour in adults. The periodic limb movements must be accompanied by sleep disturbance and excessive daytime sleepiness. The association with sleep disturbance and excessive daytime sleepiness is controversial, however, and the aetiology is unclear. This topic focuses on the diagnosis and management of PLMD in adults.
History and exam
Key diagnostic factors
- poor sleep
- daytime somnolence and fatigue
- periodic limb movements (mostly legs)
Other diagnostic factors
- age >70 years
- re-enactment of dreams during the night
- irresistible urge to move legs, and abnormal sensations in lower limbs
- early-morning dry mouth
- elevated body mass index
- withdrawal from benzodiazepines or barbiturates
- history of neuroleptic medication
- history of dopaminergic medication
- iron deficiency
- diabetes mellitus
- spinal cord injury
- episodes of sudden onset of sleep during the day; may or may not be associated with loss of muscle tone
- age >70 years
- female sex
1st investigations to order
- polysomnography: electromyography (EMG) evaluation of limb movements
- polysomnography: EEG evaluation
- polysomnography: assessment of sleep-disordered breathing
- serum ferritin
- Epworth's Sleepiness Scale
primary PLMD: with restless legs syndrome
primary PLMD: without restless legs syndrome
- Nocturnal epilepsy
- Sleep-disordered breathing
- Sleep starts
- Assessment to management of adult insomnia
- International classification of sleep disorders, 3rd ed (ICSD-3)
Sleep apnoea in adults (obstructive)More Patient leaflets
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