Periodic Limb Movement Disorder (PLMD)

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Basics

Description

Sleep-related movement disorder characterized by periodic limb movements of sleep (PLMS) with significant sleep disturbance and/or daytime functional impairment:

  • PLMS demonstrated during polysomnography (PSG)
  • PLMS are repetitive contractions of 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 and/or functional impairment is necessary for diagnosis.
  • Complaints include insomnia, nonrestorative sleep, daytime fatigue, somnolence.
  • Bed partner may complain of patient’s movements.
  • Other sleep disorders such as obstructive sleep apnea (OSA), narcolepsy, and restless legs syndrome do not explain the PLMS.
  • No associated restlessness or dysesthesia while awake
    • If there is an associated sensory perception or restlessness, the diagnosis is not PLMD but possibly restless leg syndrome (RLS).
  • System(s) affected: musculoskeletal, nervous
  • Synonym(s) referring to the PLMS: nocturnal myoclonus; sleep myoclonus

Epidemiology

Incidence
  • PLMD is rare, affecting children and adults (1).
  • PLMS occurs in >15% of insomnia patients.
  • PLMS are frequent in rapid eye movement (REM) sleep behavior disorder (RBD) occurring during REM sleep.
  • PLMS are frequent in narcolepsy, in OSA, and during initiation of CPAP.

Prevalence
  • No 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 PLMD.
  • PLMD is much less common: <5% of adults, but also underdiagnosed (1)
  • 85% of RLS patients have PLMS (2).

Etiology and Pathophysiology

  • Understudied; most data reports on PLMS as it pertains to RLS:
    • Brain iron deficiency causing CNS dopamine dysregulation
    • 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) and decreased incidence of PLMS in schizophrenia
  • 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 (dopaminergic)
      • Sedating antihistamines

Genetics
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
  • History of prematurity

General Prevention

  • Promoting adequate sleep
  • Avoid PLMS triggers such as iron deficiency, frequently observed in children (3).
  • Awareness, including family history

Commonly Associated Conditions

  • Narcolepsy
  • 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 disorder, anxiety, oppositional behaviors

Pediatric Considerations

  • PLMD may precede overt RLS by years (3).
  • Association with RLS is more common.
  • Symptoms may be more resultant than in adults (4).
  • Association and differential diagnosis with ADHD, oppositional behaviors, mood disorders, growing pains (3)

Pregnancy Considerations
PLMD is not well studied in pregnant women; implying from literature on RLS with PLMS in pregnant women:

  • May be secondary to iron, folate deficiency
  • Most severe in the 3rd trimester
  • Usually resolves after delivery

Geriatric Considerations

  • Potential source of sleep disturbance
  • May cause or exacerbate circadian disruption and “sundowning”
  • Medications that may trigger or exacerbate PLMs, which can lead to PLMD
  • PLMS may increase risk of atrial fibrillation in elderly.

-- To view the remaining sections of this topic, please or --

Basics

Description

Sleep-related movement disorder characterized by periodic limb movements of sleep (PLMS) with significant sleep disturbance and/or daytime functional impairment:

  • PLMS demonstrated during polysomnography (PSG)
  • PLMS are repetitive contractions of 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 and/or functional impairment is necessary for diagnosis.
  • Complaints include insomnia, nonrestorative sleep, daytime fatigue, somnolence.
  • Bed partner may complain of patient’s movements.
  • Other sleep disorders such as obstructive sleep apnea (OSA), narcolepsy, and restless legs syndrome do not explain the PLMS.
  • No associated restlessness or dysesthesia while awake
    • If there is an associated sensory perception or restlessness, the diagnosis is not PLMD but possibly restless leg syndrome (RLS).
  • System(s) affected: musculoskeletal, nervous
  • Synonym(s) referring to the PLMS: nocturnal myoclonus; sleep myoclonus

Epidemiology

Incidence
  • PLMD is rare, affecting children and adults (1).
  • PLMS occurs in >15% of insomnia patients.
  • PLMS are frequent in rapid eye movement (REM) sleep behavior disorder (RBD) occurring during REM sleep.
  • PLMS are frequent in narcolepsy, in OSA, and during initiation of CPAP.

Prevalence
  • No 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 PLMD.
  • PLMD is much less common: <5% of adults, but also underdiagnosed (1)
  • 85% of RLS patients have PLMS (2).

Etiology and Pathophysiology

  • Understudied; most data reports on PLMS as it pertains to RLS:
    • Brain iron deficiency causing CNS dopamine dysregulation
    • 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) and decreased incidence of PLMS in schizophrenia
  • 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 (dopaminergic)
      • Sedating antihistamines

Genetics
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
  • History of prematurity

General Prevention

  • Promoting adequate sleep
  • Avoid PLMS triggers such as iron deficiency, frequently observed in children (3).
  • Awareness, including family history

Commonly Associated Conditions

  • Narcolepsy
  • 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 disorder, anxiety, oppositional behaviors

Pediatric Considerations

  • PLMD may precede overt RLS by years (3).
  • Association with RLS is more common.
  • Symptoms may be more resultant than in adults (4).
  • Association and differential diagnosis with ADHD, oppositional behaviors, mood disorders, growing pains (3)

Pregnancy Considerations
PLMD is not well studied in pregnant women; implying from literature on RLS with PLMS in pregnant women:

  • May be secondary to iron, folate deficiency
  • Most severe in the 3rd trimester
  • Usually resolves after delivery

Geriatric Considerations

  • Potential source of sleep disturbance
  • May cause or exacerbate circadian disruption and “sundowning”
  • Medications that may trigger or exacerbate PLMs, which can lead to PLMD
  • PLMS may increase risk of atrial fibrillation in elderly.

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