title: Loss of rapid eye movement sleep atonia in patients with REM sleep behavioral disorder, narcolepsy, and isolated loss of REM atonia.
abstract: OBJECTIVE
  To compare the amounts of REM sleep without atonia (RSWA) between patients with REM sleep behavior disorder (RBD), "isolated loss of REM atonia," narcolepsy, and control subjects and determine if there were threshold values for the amount of RSWA that differentiate each group from controls.
  
  
  METHODS
  Retrospective analyses of polysomnography (PSG) records were used employing strict quantitative criteria for the measurement of phasic and tonic EMG activity during REM sleep. The PSG recordings of 47 individuals were analyzed (RBD 16, isolated loss of REM atonia 11, narcolepsy 10, control 10).
  
  
  RESULTS
  Patients with the diagnosis of isolated loss of REM atonia had significantly lower levels of EMG activity during REM sleep than those with RBD but higher than control subjects. RSWA was higher in narcolepsy than in loss of REM atonia but lower than for RBD patients. Receiver operating characteristic (ROC) curves provided threshold values with high specificity and sensitivity in all patient groups with a cutoff value ≥ 1.22% (100% correctly classified) for phasic and ≥ 3.17% for tonic (92% correctly classified) EMG activity in RBD.
  
  
  CONCLUSIONS
  Quantification of REM sleep EMG activity can successfully differentiate RBD and isolated loss of REM atonia patients from controls. The consistently increased amount of RSWA in patients with narcolepsy indicates that this can be an additional marker for a diagnosis of narcolepsy. Longitudinal studies of patients with isolated loss of REM atonia are needed to evaluate if these patients are at risk of developing RBD or neurodegenerative disorders.
authors.affiliation: Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, London UK.
authors.forename: Aytakin
authors.initials: A
authors.lastname: Khalil
authors.forename: Mary-Anne
authors.initials: MA
authors.lastname: Wright
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Walker
authors.forename: Sofia H
authors.initials: SH
authors.lastname: Eriksson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016022:Case-Control Studies; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009123:Muscle Hypotonia / Q000175:diagnosis*; D009290:Narcolepsy / Q000175:diagnosis*; D017286:Polysomnography / Q000379:methods; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis*; D012372:ROC Curve; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012895:Sleep, REM / Q000502:physiology*
keywords: EMG; REM sleep; REM sleep behavior disorder (RBD); narcolepsy; polysomnography