Quantitative EMG criteria for diagnosing idiopathic REM sleep behavior disorder.
OBJECTIVE
The purpose of this study is to determine the diagnostic cutoff for the proportion of rapid eye movement (REM) sleep with tonic and phasic activities of the submentalis muscle activity that can be used to diagnose REM sleep behavior disorder (RBD).


METHODS
Seventeen patients clinically diagnosed as idiopathic RBD and 15 age- and gender-matched controls were studied. Surface electromyography was recorded from the submentalis muscle, and two sleep technologists manually identified epochs with tonic and phasic activities during REM sleep. Receiver operating characteristic (ROC) curves were constructed to find the optimal cutoff values for diagnosing RBD using the proportion of REM sleep with tonic and phasic activities of the submentalis muscle. Cohen's kappa coefficient was calculated to evaluate interrater reliability.


RESULTS
The cutoff value with the optimal sensitivity and specificity was 6.5% for the proportion of REM sleep with tonic activity (sensitivity, 94.1%; specificity, 93.3%; area under the ROC curve, 0.976) and 9.5% for the proportion of REM sleep with phasic activity (sensitivity, 94.1%; specificity, 93.3%; area under the ROC curve, 0.992). The cutoff value required to achieve a specificity of 100% was 8.9% for tonic activity and 11.1% for phasic activity. Cohen's kappa coefficient between two scorers was 0.96 (95% confidence interval, 0.95-0.97) and 0.95 (95% confidence interval, 0.94-0.95) for tonic and phasic activities, respectively (both p < 0.001).


CONCLUSIONS
Identifying periods of tonic and phasic activities of the submentalis muscle during REM sleep is useful to discriminate patients with idiopathic RBD from controls.
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 86 Asanbyeongwon-gil, Songpa-gu, Seoul, 138-736, Korea, salee@amc.seoul.kr.
Sang-Ahm
SA
Lee
Cheon Sik
CS
Kim
Cheon Uoong
CU
Cho
Bomi
B
Kim
Gha-Hyun
GH
Lee
D000368:Aged; D000369:Aged, 80 and over; D002680:Chin / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009129:Muscle Tonus / Q000502:physiology; D009334:Neck Muscles / Q000503:physiopathology; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000503:physiopathology*; D012372:ROC Curve; D012016:Reference Values; D012680:Sensitivity and Specificity; D012895:Sleep, REM / Q000502:physiology