Neurology · Year 3 · from Neurology

Case 3: REM Sleep Behavior Disorder

Patient Demographics

  • Age: 68 years old
  • Sex: Male
  • Occupation: Retired accountant

Chief Complaint

Wife reports: "He's been acting out his dreams. Last week he punched me while he was asleep. I'm scared to sleep in the same bed."

History of Present Illness

Mr. William Chen is a 68-year-old man brought by his wife for evaluation of abnormal behaviors during sleep. For the past 2 years, he has been increasingly active during sleep, talking, yelling, and moving his arms and legs. Initially, he would just mumble and wave his arms. Over the past 6 months, the behaviors have become more violent - he has punched his wife, fallen out of bed twice, and knocked a lamp off the nightstand. His wife reports that his movements seem to correspond to "fighting" or "running" as he often yells things like "Get away!" or "I'll get you!" When she wakes him, he clearly recalls dreaming about being attacked or chased. The episodes occur later in the night (after 3-4 hours of sleep). He has no memory of the actual movements, only the dream content.

Additional Sleep History

  • No history of sleepwalking in childhood
  • No snoring or witnessed apneas
  • Occasional restless legs in evening (mild)
  • Normal sleep duration and quality otherwise

Past Medical History

  • Hypertension
  • Mild constipation (chronic)
  • Noticed decreased sense of smell over past several years

Medications

  • Lisinopril 20 mg daily
  • Docusate sodium as needed

Family History

  • Father: Parkinson disease, diagnosed at age 72
  • No other neurological diseases known

Social History

  • Retired accountant
  • Non-smoker
  • Occasional glass of wine with dinner
  • Married 42 years

Neurological Examination

  • Mental Status: Normal cognition (MoCA 28/30)
  • Cranial Nerves: Diminished sense of smell bilaterally (hyposmia)
  • Motor:
  • Subtle rigidity right upper extremity (cogwheeling on distraction)
  • No resting tremor observed
  • Mildly decreased arm swing on right when walking
  • Gait: Slightly slowed, mildly reduced stride length
  • Reflexes: Normal

Clinical Image

Image: Polysomnography recording demonstrating REM sleep without atonia - the characteristic finding in REM sleep behavior disorder, showing sustained muscle activity in the chin EMG during REM sleep.

Image Source: Wikimedia Commons Attribution: Medical education, Public Domain URL: https://commons.wikimedia.org/wiki/File:REM_without_atonia.png

Diagnostic Studies

Polysomnography (Video-PSG):

  • Sleep architecture: Normal
  • AHI: 4 (normal)
  • REM sleep: 18% of total sleep time
  • REM Without Atonia (RSWA): Present - sustained chin EMG activity during REM
  • Video: During REM periods, patient observed thrashing arms, kicking legs, and yelling "Stop!" while appearing to be dreaming

Assessment and Diagnosis

  1. REM Sleep Behavior Disorder (RBD) - confirmed by PSG showing REM without atonia and video documentation of dream enactment behavior
  2. High risk for future neurodegenerative disease - particularly alpha-synucleinopathy
  3. Early parkinsonian signs present:
  • Hyposmia
  • Subtle right-sided rigidity
  • Decreased arm swing
  • Constipation (autonomic involvement)

Significance of RBD

Critical Prognostic Information:

  • RBD is strongly associated with future development of alpha-synucleinopathies:
  • Parkinson disease
  • Dementia with Lewy bodies
  • Multiple system atrophy
  • 80%+ of patients with idiopathic RBD will develop a neurodegenerative disease within 10-15 years
  • Average time from RBD onset to neurodegenerative diagnosis: 10-15 years

This patient already shows subtle parkinsonian features, suggesting he is in the prodromal phase of Parkinson disease.

Management Plan

Safety Measures (Highest Priority):

  • Remove dangerous objects from bedroom (nightstands, lamps)
  • Pad floor beside bed with mattress or cushions
  • Lower bed or consider mattress on floor
  • Consider sleeping in separate beds until behaviors controlled
  • Secure windows
  • Remove firearms from bedroom

Pharmacologic Treatment:

First-line options:

  • Melatonin 3-12 mg at bedtime - Start with 3 mg, increase as needed
  • Mechanism unclear but effective in ~50%
  • Excellent safety profile
  • Try first due to safety
  • Clonazepam 0.25-1 mg at bedtime - If melatonin insufficient
  • Very effective (~90% response)
  • Use caution in elderly (fall risk, cognitive effects)
  • Start low (0.25 mg), increase slowly
  • Monitor for daytime sedation

Patient started on melatonin 6 mg at bedtime

Counseling Regarding Prognosis:

  • Discussed with patient and wife the association between RBD and neurodegenerative disease
  • Explained that he already shows some subtle signs that may indicate early Parkinson disease
  • Emphasized that not all patients develop overt disease, and timeline is variable
  • Discussed potential future symptoms to watch for
  • Offered support resources

Referral to Movement Disorders Specialist:

  • For evaluation of subtle parkinsonian signs
  • Discussion of monitoring vs. early treatment options
  • Participation in research studies on neuroprotective strategies

Follow-Up (3 months later)

Treatment Response:

  • Melatonin 6 mg: Partial improvement
  • Added clonazepam 0.5 mg: Significant improvement
  • Wife reports rare residual talking but no violent behaviors
  • No more injuries
  • Couple sleeping in same bed again

Movement Disorder Follow-Up:

  • Confirmed early parkinsonism
  • No treatment initiated yet (symptoms minimal)
  • Monitoring every 6 months
  • Enrolled in longitudinal research study

Teaching Points

  1. RBD is characterized by loss of normal REM sleep atonia - patients physically act out dreams, often violent
  1. PSG shows REM without atonia (RSWA) - this is the diagnostic hallmark
  1. Safety is the first priority - bedroom modifications to prevent injury to patient and bed partner
  1. RBD is highly predictive of future alpha-synucleinopathy:
  • >80% develop Parkinson disease, DLB, or MSA
  • This is one of the strongest known prodromal markers
  1. Treatment: melatonin (safer) and clonazepam (more effective)
  1. Distinguish from NREM parasomnias:
  • RBD: Later in night (REM-predominant), dream recall, eyes closed, older adults
  • NREM (sleepwalking, night terrors): First third of night, no recall, eyes open, more common in children
  1. Clinical pearls suggesting prodromal Parkinson disease:
  • RBD
  • Hyposmia (decreased smell)
  • Constipation
  • Depression
  • Subtle motor signs

Key Teaching Points Summary

Obstructive Sleep Apnea

  • STOP-BANG score ≥5 = high risk for moderate-severe OSA
  • AHI: Mild 5-15, Moderate 15-30, Severe >30
  • CPAP is first-line for moderate-severe OSA
  • Associated with resistant hypertension, atrial fibrillation, stroke

Narcolepsy

  • Type 1 = with cataplexy (low CSF orexin); Type 2 = without cataplexy
  • MSLT diagnostic: Mean sleep latency <8 min with ≥2 SOREMPs
  • Cataplexy: emotion-triggered muscle weakness with preserved consciousness
  • Treatment: Modafinil for EDS; sodium oxybate for cataplexy

REM Sleep Behavior Disorder

  • Dream enactment behavior with REM without atonia on PSG
  • >80% will develop alpha-synucleinopathy (PD, DLB, MSA)
  • Safety measures are highest priority
  • Treatment: Melatonin (first-line for safety), clonazepam (highly effective)

All cases for this lecture as Markdown