Periodic Limb Movement Disorder (PLMD)

Periodic Limb Movement Disorder (PLMD) is a topic covered in the 5-Minute Clinical Consult.

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  • Sleep-related movement disorder with episodes of periodic limb movements (PLMs) occurring during sleep (1)[A] characterized by:
    • Periodic limb movements of sleep (PLMS) demonstrated during polysomnography that are combined with clinical symptoms
    • PLMS are repetitive contractions of the tibialis anterior muscles occurring mainly in non–rapid eye movement (NREM) sleep.
    • Movements consist of unilateral or bilateral, simultaneous or not, rhythmical extension of the big toe and ankle dorsiflexion.
    • Sometimes, knee and hip flexion is noted.
    • Arm movements or more generalized movements occur less commonly.
    • Movements might be associated with cortical arousals from sleep unbeknownst to the patient (PLMs with arousals—PLMA).
    • A clinical history of significant sleep disturbance or functional impairment is necessary for diagnosis.
    • Complaints include insomnia, nonrestorative sleep, daytime fatigue, and/or somnolence.
    • Bed partner may complain of patient’s movements.
    • Other sleep disorders such as obstructive sleep apnea (OSA), narcolepsy, restless legs syndrome do not explain the PLMS (2)[A].
  • No wakeful perception of the PLMS or associated restlessness
    • If there is wakeful perception, the diagnosis is not periodic limb movement disorder (PLMD) but possibly restless leg syndrome (RLS).
  • System(s) affected: musculoskeletal, nervous
  • Synonym(s) referring to the PLMS: nocturnal myoclonus; sleep myoclonus


  • PLMD is rare, reported in both children and adults (1).
  • PLMS occurs in at least 15% of insomnia patients.
  • PLMS is frequent in rapid eye movement (REM) sleep behavior disorder (RBD) occurring during REM sleep.
  • PLMS is frequent in narcolepsy, in OSA, and during initiation of continuous positive airway pressure (CPAP).

  • No predominant sex preference; male = female
  • PLMS >5/hr is uncommon before age 40 years.
  • PLMS increases with age: 45% of patients >65 years exhibit PLMS >5/hr but not necessarily PLMD.
  • PLMD is much less common: <5% of adults but also underdiagnosed (1).
  • 85% of RLS patients have PLMS (3).

Etiology and Pathophysiology

  • Understudied; most data pertain to PLMS in RLS.
  • Brain iron deficiency
  • Suprasegmental disinhibition at the brainstem and spinal cord levels
  • Spinal cord excitability
  • CNS dopamine dysregulation supported by increased incidence of PLMS in untreated Parkinson disease (PD) patients
  • Decreased incidence of PLMS in schizophrenia patients
  • Triggering and exacerbating factors:
    • Peripheral neuropathy
    • Arthritis
    • Renal failure
    • Synucleinopathies (multiple-system atrophy)
    • Spinal cord injury
    • Pregnancy
    • Medications:
      • Most antidepressants (except bupropion or desipramine) and lithium
      • Some antipsychotic and antidementia medications
      • Antiemetics (metoclopramide)
      • Antihistamines

BTBD9 on chromosome 6p associated with PLMS in patients with or without RLS but not in RLS patients without PLMS

Risk Factors

  • Family history of RLS
  • Iron deficiency and associated conditions
  • Peripheral neuropathy
  • Arthritis, orthopedic problems
  • Chronic limb pain or discomfort

General Prevention

  • Adequate nightly sleep
  • Avoid PLMS triggers such as iron deficiency, frequently observed in children (4).
  • Awareness, including family history

Commonly Associated Conditions

  • Narcolepsy
  • Iron deficiency
  • End-stage renal disease (ESRD)
  • Cardiovascular disease; stroke
  • Gastric surgery
  • Pregnancy
  • Arthritis
  • Synucleinopathies (multiple-system atrophy)
  • Lumbar spine disease; spinal cord injury
  • Peripheral neuropathy
  • Insomnia, insufficient sleep, parasomnias
  • ADHD
  • Mood disorders, anxiety, oppositional behaviors
Pediatric Considerations
  • PLMD may precede overt RLS by years (4).
  • Association with RLS is more common than in adults.
  • Symptoms may be more consequential than in adults (5)[B].
  • Association and differential diagnosis with ADHD, oppositional behaviors, mood disorders, growing pains (4)
Pregnancy Considerations
  • May be secondary to iron or folate deficiency
  • Most severe in the 3rd trimester
  • Usually subsides after delivery
Geriatric Considerations
  • May become a significant source of sleep disturbance
  • May cause or exacerbate circadian disruption and “sundowning”
  • Many medications given to the elderly may trigger or exacerbate PLMs, which can lead to PLMD or RLS.

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