Elevated PEM (phasic electromyographic metric) rates identify rapid eye movement behavior disorder patients on nights without behavioral abnormalities.
OBJECTIVE
To determine the validity of the phasic electromyographic metric (PEM) to differentiate patients with a history suggestive of rapid eye movement behavior disorder (REMBD) on laboratory nights without overt dream-enactment behavior.


METHODS
PEM was quantified as the % of 2.5-sec intervals with phasic muscle activity of 100-msec duration with an amplitude of at least 4 times background activity in 11 patients and 31 elderly controls. Data were derived from both REM and NREM sleep from 5 muscle groups (mentalis, left/right anterior tibialis, left/right brachioradialis).


RESULTS
Relative to controls, REMBD patients had significantly higher levels of PEM activity in all recordings. The largest differences occurred during REM sleep for the mentalis and brachioradialis channels. Similar results were obtained by limiting quantification of PEM to the final REM period of the night and could be accomplished by individuals with no previous familiarity with polysomnography.


CONCLUSIONS
PEM may be a useful metric to characterize the REM related phasic muscle activity on patients with a history of REMBD, even when no overt dream-enactment behaviors are detected on a laboratory night.
Bliwise
Donald L
DL
Emory Healthcare Program in Sleep and Department of Neurology, Emory University School of Medicine, Atlanta, GA 30329, USA. dbliwis@emory.edu
Rye
David B
DB
D000368:Aged; D002680:Chin; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation; D017286:Polysomnography; D015995:Prevalence; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*