Searching for a marker of REM sleep behavior disorder: submentalis muscle EMG amplitude analysis during sleep in patients with narcolepsy/cataplexy.
OBJECTIVE
To evaluate the amplitude of submentalis muscle EMG activity during sleep in patients with narcolepsy/cataplexy with or without REM sleep behavior disorder (RBD).


METHODS
Observational study with consecutive recruitment.


METHODS
Sleep laboratory.


METHODS
Thirty-four patients with narcolepsy/cataplexy and 35 age-matched normal controls.


RESULTS
Half the patients (17 subjects) had a clinical and video polysomnographic diagnosis of RBD. The average amplitude of the rectified submentalis muscle EMG signal was used to assess muscle atonia, and the new REM sleep Atonia Index was computed. Chin muscle activations were detected and their duration and interval analyzed. REM sleep Atonia Index was lower in both patient groups (with narcolepsy patients with RBD showing the lowest values) with respect to controls, and it did not correlate with age as it did in controls. The total number of chin EMG activations was significantly higher in both patient groups than controls. No significant differences were found between the two groups of patients, although more chin EMG activations were noted in narcolepsy patients with RBD than those without.


CONCLUSIONS
Elevated muscle activity during REM sleep is the only polysomnographic marker of RBD. This study shows that polysomnographically evident RBD is present in many patients with narcolepsy/ cataplexy. This condition might be specific to narcolepsy/cataplexy, reflecting a peculiar form of REM sleep related motor dyscontrol (i.e., status dissociatus), paving the way to enacting dream behaviors, and correlated with the specific neurochemical and neuropathological substrate of narcolepsy/cataplexy.
Sleep Research Centre, Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy. rferri@oasi.en.it
Raffaele
R
Ferri
Christian
C
Franceschini
Marco
M
Zucconi
Stefano
S
Vandi
Francesca
F
Poli
Oliviero
O
Bruni
Carlo
C
Cipolli
Pasquale
P
Montagna
Giuseppe
G
Plazzi
D000293:Adolescent; D000328:Adult; D000368:Aged; D002385:Cataplexy / Q000175:diagnosis* / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009290:Narcolepsy / Q000175:diagnosis* / Q000503:physiopathology; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult