Improved computation of the atonia index in normal controls and patients with REM sleep behavior disorder
ABSTRACT The aim of this study was to evaluate the effects of a simple method of noise reduction before the calculation of the REM sleep atonia index (AI) on a large number of recordings from different normal controls and patient groups.
Eighty-nine subjects were included: 25 young controls, 10 aged controls, 31 untreated patients with idiopathic REM sleep behavior disorder (iRBD), 8 treated patients with iRBD, 10 patients with multiple system atrophy (MSA) and 5 patients with obstructive sleep apnea syndrome (OSAS). The average amplitude of the rectified submentalis muscle EMG signal was then obtained for all 1-s mini epochs of REM sleep. The new correction method was implemented by subtracting from each mini epoch the minimum value found in a moving window including the 60 mini epochs surrounding it.
Two arbitrary thresholds were established at AI<0.8 and 0.8<AI<0.9; all young controls presented AI>0.9; this was not true for aged controls, 3 of whom presented 0.8<AI<0.9 but none had AI<0.8; on the contrary 74.4% of all iRBD showed AI<0.9, with 38.5% of the whole group having AI<0.8 and only 25.6% with AI>0.9. All MSA patients showed AI<0.8.
After the introduction of this new method for noise reduction, REM sleep AI index values lower than 0.8 were strongly indicative of altered (reduced) chin EMG atonia during REM sleep; values of AI between 0.8 and 0.9 indicated a less evident involvement of atonia, and values above 0.9 characterized the majority of normal recordings.
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ABSTRACT: The authors hypothesized that if locomotor drive increases along with rapid eye movement (REM) sleep without atonia in idiopathic REM sleep behavior disorder (RBD), then RBD patients would have greater corticomuscular coherence (CMC) values during REM sleep than at other sleep stages and than in healthy control subjects during REM sleep. To explore this hypothesis, we analyzed beta frequency range CMC between sensorimotor cortex electroencephalography (EEG) and chin/limb muscle EMG in idiopathic RBD patients. Eleven drug naive idiopathic RBD patients and 11 age-matched healthy control subjects were included in the present study. All participants completed subjective sleep questionnaires and underwent polysomnography for one night. The CMC value between EEGs recorded at central electrodes and EMGs acquired at leg and chin muscles were computed and compared by repeated measures analysis of variance (ANOVA). Sleep stages and muscle (i.e., chin vs. leg) served as within-subject factors, and group served as the between-subject factor. Repeated measures ANOVA revealed no significant main effect of group (F(1,20) = 0.571, p = 0.458) or muscle (F(1,20) = 1.283, p = 0.271). However, sleep stage was found to have a significant main effect (F(2.067,41.332) = 20.912, p < 0.001). The interaction between group and sleep stage was significant (F(2.067,41.332) = 3.438, p = 0.040). RBD patients had a significantly higher CMC value than controls during REM sleep (0.047 ± 0.00 vs. 0.052 ± 0.00, respectively, p = 0.007). This study reveals increased CMC during REM sleep in patients with RBD, which indicates increased cortical locomotor drive. Furthermore, this study supports the hypothesis that sufficient locomotor drive plays a role in the pathophysiology of RBD in addition to REM sleep without atonia.Frontiers in Neurology 04/2012; 3:60. DOI:10.3389/fneur.2012.00060
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ABSTRACT: Sleep specialists are frequently referred adults with epilepsy to evaluate their sleep/wake complaints, sometimes to determine whether their paroxysmal nocturnal behaviors are epileptic or not. Many patients with epilepsy have at least one parasomnia (some more than one), and the sleep specialists are often asked to differentiate and treat these. Sleep specialists review which primary sleep disorders are more common in adults with epilepsy and how to evaluate and best treat these. The authors summarize (1) how to evaluate and differentiate parasomnias using video-polysomnography; (2) the value of sleep deprivation and loud auditory stimuli to increase the likelihood of provoking a non-rapid eye movement arousal parasomnia with a single night of video-polysomnography; and (3) how to score excessive muscle activity during rapid eye movement sleep to confirm a diagnosis of rapid eye movement sleep behavior disorder. The clinical semiology and video-polysomnography features of simple and complex sleep-related movement disorders and parasomnias are reviewed.Journal of clinical neurophysiology: official publication of the American Electroencephalographic Society 03/2011; 28(2):120-40. DOI:10.1097/WNP.0b013e3182120fed · 1.60 Impact Factor
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ABSTRACT: Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by loss of muscle atonia during REM sleep that results in motor behaviors. Diagnosis of RBD involves a clinical interview in which history of dream enactment behaviors is elicited and a subsequent overnight polysomnography (PSG) evaluation to assess for REM sleep without atonia (RWA) and/or observe motor behaviors during REM sleep. Therefore, the nature of RBD diagnosis involves both subjective and objective measurements that attempt to qualify and quantify the different diagnostic sub-criteria. The primary aim of the current study was to identify and summarize the available clinical measurements that have been used for RBD assessment. Two major online databases (MEDLINE and PsycInfo) were searched for articles developing, validating, or evaluating psychometric properties of the RBD diagnostic criteria or methods used for diagnosis. Studies of adult subjects (18 years or more) that included sufficient psychometric data for validation were included. Fifty-eight studies were found to meet review criteria. The objective measurements for assessment of RBD reviewed included visual electromyographic (EMG) scoring methods, computerized EMG scoring methods, cardiac (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy, actigraphy, behavioral classification and video analysis. Subjective measurements of RBD included interviews and questionnaires. Sleep history may be sufficient for diagnosis of RBD in some populations. However, PSG is necessary for a definitive diagnosis. EMG scoring methods vary in definition used and there is no single accepted approach to scoring muscle activity. Additional validation studies are required for establishing cutoff scores for the different methods. Questionnaires were shown to be appropriate screening tools, yet further validation in different populations is necessary.Sleep Medicine Reviews 12/2011; 16(5):415-29. DOI:10.1016/j.smrv.2011.08.004 · 9.14 Impact Factor