Sleep-Related Movement Disorders

Introduction & Overview - Night Moves Primer

• Simple, often stereotyped, movements occurring during or near sleep; not primarily due to other conditions.
• Key features: Repetitive, may disrupt sleep, cause daytime fatigue, or injury.
• Diagnosis: Relies on clinical history, sometimes actigraphy or Polysomnography (PSG).
• Differentiate from: Parasomnias (complex behaviors) & nocturnal seizures.
• Common examples: Restless Legs Syndrome (RLS), Periodic Limb Movement Disorder (PLMD), Sleep-related Bruxism.

⭐ Polysomnography (PSG) is crucial for diagnosing Periodic Limb Movement Disorder (PLMD), defined by a PLM index ≥15/hour in adults (or ≥5/hour in children).

Restless Legs Syndrome (RLS) - Itchy Twitchy Legs

• Willis-Ekbom Disease: Urge to move legs, often with unpleasant sensations. Worse at rest/night, relieved by movement.
• URGE Criteria (Diagnosis): 📌
  • Urge to move legs
  • Rest or inactivity worsens symptoms
  • Getting up or movement relieves symptoms
  • Evening or night worsening of symptoms
• Etiology:
  • Primary: Idiopathic/familial.
  • Secondary: Iron deficiency (serum ferritin <75 ng/mL), uremia, pregnancy, peripheral neuropathy, medications (e.g., SSRIs, antihistamines).
• Investigations: Primarily clinical diagnosis. Serum ferritin essential. Polysomnography (PSG) may show Periodic Limb Movements of Sleep (PLMS) in >80% cases, but not required for RLS diagnosis.
• Management:
  • Non-pharmacological: Lifestyle modification (exercise, sleep hygiene, avoid triggers). Iron supplementation if ferritin <75 ng/mL.
  • Pharmacological: First-line options include Dopamine agonists (Pramipexole, Ropinirole) OR Alpha-2-delta ligands (Gabapentin, Pregabalin).
  • ⚠️ Be cautious of augmentation (paradoxical worsening) with long-term dopamine agonist use.

⭐ RLS demonstrates a strong association with iron deficiency; always check serum ferritin levels (target >75 ng/mL for supplementation).

Periodic Limb Movement Disorder (PLMD) - Unknowing Kicks

• Repetitive, stereotyped limb movements (kicks/jerks) during sleep; mainly lower limbs.
• Patient unaware; bed partner reports. Causes sleep fragmentation, daytime sleepiness.
• Diagnosis: Polysomnography (PSG) essential.
  • Adults: ≥ 15 PLM/hour (PLMI). Children: ≥ 5 PLM/hour.
  • Movements: 0.5-10s duration; ≥ 4 in series; 5-90s interval.
• Associations:
  • Often co-occurs with RLS.
  • Iron deficiency, uremia, spinal cord issues.
  • Meds: SSRIs, TCAs, dopamine blockers.
• Treatment:
  • Treat cause (e.g., iron).
  • Dopaminergic agents (e.g., pramipexole, ropinirole).
  • Gabapentin, pregabalin.
  • Clonazepam (cautious use).

⭐ Polysomnography (PSG) is mandatory for PLMD diagnosis, differentiating it from other sleep movements.

Other Sleep Movement Issues - Grinds, Rocks & Cramps

• Sleep Bruxism (Grinding)
  • Repetitive jaw muscle activity (clenching/grinding) in sleep.
  • Features: Tooth wear, jaw pain/hypertrophy, headaches. Polysomnography (PSG) may show masseter EMG activity.
  • Associations: Stress, anxiety, Obstructive Sleep Apnea (OSA), Restless Legs Syndrome (RLS), SSRIs.
  • Management: Dental guards, stress reduction, botulinum toxin (severe cases).
• Sleep-Related Rhythmic Movement Disorder (SRRMD)
  • Repetitive, stereotyped, rhythmic motor behaviors (e.g., head banging, body rocking) occurring near sleep onset or during sleep.
  • Onset: Typically infancy/early childhood; often self-limiting.
  • Associations: Neurodevelopmental disorders (e.g., Autism Spectrum Disorder).
  • Management: Safety measures (e.g., padding crib), behavioral therapies; clonazepam if severe or risk of injury.
  • 
• Sleep-Related Leg Cramps
  • Sudden, painful, involuntary muscle contractions, typically in calf or foot, during sleep.
  • Features: Awakens patient; relief obtained with stretching or massage.
  • Prevalence: Increases (↑) with age, common in pregnancy.
  • Associations: Dehydration, electrolyte imbalance (e.g., ↓K, ↓Mg, ↓Ca), peripheral vascular disease, neuropathy, certain medications (e.g., diuretics).
  • Management: Stretching exercises, adequate hydration.

⭐ Sleep bruxism can lead to significant dental damage (e.g., tooth attrition, fractures) and temporomandibular joint (TMJ) disorders if left unmanaged.

High‑Yield Points - ⚡ Biggest Takeaways

• Restless Legs Syndrome (RLS): Uncomfortable urge to move legs, worse at rest/evening, relieved by activity.
• RLS is strongly linked to iron deficiency (check serum ferritin), uremia, and pregnancy.
• Periodic Limb Movement Disorder (PLMD): Repetitive limb movements during sleep, diagnosed by polysomnography (PSG).
• RLS/PLMD treatment: Dopamine agonists (e.g., pramipexole) or alpha-2-delta ligands (e.g., gabapentin).
• Sleep-related bruxism: Involuntary teeth grinding/clenching during sleep, causing dental damage and TMJ pain.
• Sleep-related Rhythmic Movement Disorder (RMD): Includes head banging/body rocking, common in children, usually benign and self-limiting.