In REM Sleep Behaviour Disorder (RBD), which electrophysiological finding confirms the diagnosis on polysomnography?

• A Apnea-Hypopnea Index (AHI) >15 events/hour during REM sleep
• B REM sleep without atonia (RSWA) — persistent EMG activity during REM ✓
• C K-complexes and sleep spindles during enacted behaviors
• D Alpha intrusion into slow-wave sleep (NREM stage N3)

Explanation

The PSG hallmark of REM Sleep Behaviour Disorder is REM Sleep Without Atonia (RSWA) — loss of the normal muscle atonia during REM sleep, documented by increased EMG activity on chin/limb leads during REM. Clinically this manifests as dream-enactment behaviors (punching, kicking, shouting). RBD is a prodromal marker of synucleinopathies (Parkinson's disease, LBD, MSA) — up to 80% of idiopathic RBD patients will develop these conditions within 10–15 years. Treatment: melatonin (first-line, reduces injury) and low-dose clonazepam.

Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.