Abstract Introduction Electromyography (EMG), video-polysomnography (vPSG), and wrist actigraphy have each been used to develop diagnostic algorithms for REM sleep behavior disorder (RBD). However, the extent to which they capture overlapping versus distinct motor phenomena remains unknown. We evaluated the respective contributions of actigraphy, EMG and vPSG to the measurement of REM-sleep motor activity. Methods Nine adults aged 35–75 with idiopathic RBD (n=8) or antidepressant-induced RBD (n=1) underwent vPSG and simultaneous bilateral wrist actigraphy (AX-6) at the Mount Sinai Sleep Research Center. Flexor digitorum superficialis EMG activity and video-detected movements were manually scored in 3-second mini epochs, and actigraphy signals were quantified using an acceleration-magnitude-based activity count model following timestamp synchronization. Correlation and agreement analyses were performed to assess the motor events captured by all three, any two, or by each modality independently during REM sleep. Results Across 12,941 epochs, EMG, actigraphy, and video independently detected 1,703, 1,613, and 811 motor events, of which 413 were detected concurrently by all three modalities. EMG–actigraphy, EMG–video, and actigraphy–video pairs simultaneously detected 174, 187, and 143 movements, respectively. Modalities showed moderate agreement, with an increasing order of association from EMG–actigraphy (κ = 0.27 ± 0.10) to actigraphy–video (κ = 0.41 ± 0.12) and EMG–video (κ = 0.45 ± 0.15). Of EMG-detected motor events, 49.0% were also detected by actigraphy. Conversely, 37.2% of actigraphy-detected events were detected by EMG, and 34.9% by video. Among video-detected movements, 73.4% were also captured by actigraphy and 66.5% by EMG. Actigraphy activity counts were highest for events detected by all three modalities, followed by actigraphy–video and EMG–actigraphy pairs, and were lowest for actigraphy-only events. Conclusion EMG, actigraphy, and video captured partially overlapping motor events in patients with RBD. Among all modalities, actigraphy appeared to be the most sensitive, detecting approximately half of EMG-identified motor events and an additional 63% of events not captured by EMG, whereas manually scored video was the least sensitive. Support (if any) Department of Neurology, Icahn School of Medicine at Mount Sinai.
Ryu et al. (Fri,) studied this question.