Original ArticleUsefulness of the SINBAR electromyographic montage to detect the motor and vocal manifestations occurring in REM sleep behavior disorder
Introduction
Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by increased muscle activity associated with abnormal motor and vocal behaviors occurring in REM sleep. These manifestations occur in the limbs (e.g., jerking, punching, kicking), orofacial muscles (e.g., grimacing, shouting) and even the whole body (e.g., jumping out of bed). Correct diagnosis of RBD is important because (1) RBD is frequently the initial manifestation of a neurodegenerative disease, (2) other sleep disorders such as severe sleep apnea and nocturnal frontal lobe epilepsy may mimic its symptoms, (3) patients may injure themselves and their bed partners, and (4) RBD can be treated effectively with clonazepam [1]. Diagnosis of RBD requires the use of polysomnography (PSG) with synchronized audiovisual recording to document REM sleep increased electromyographic (EMG) activity in the mentalis and limbs related to abnormal behaviors [2]. The definition of increased EMG activity during REM sleep is not specified in the standard diagnostic criteria [2] and methods of quantitative assessment of EMG activity are still under debate. The main controversy is that rules for scoring tonic and phasic EMG activity are ambiguous, and no consensus has been reached. Moreover, reliable cut-off values for these measures are lacking to clearly differentiate between normal REM sleep and REM sleep without atonia. Identification of the most appropriate EMG montage for RBD monitoring was the aim of a previous study of our group. In that previous study, we showed that simultaneous EMG recording of the mentalis, flexor digitorum superficialis in the upper limbs and extensor digitorum brevis in the lower limbs (the SINBAR EMG montage for RBD) detected the highest rates of increased EMG activity in RBD patients [3]. In the current study, we subsequently aimed to further evaluate the ability of the SINBAR EMG montage to detect the motor and vocal manifestations occurring in patients with RBD.
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Patient selection
Eleven patients from the sleep laboratories of the Departments of Neurology of Innsbruck Medical University, Austria (n = 5) and Hospital Clinic de Barcelona, Spain (n = 6) with the diagnosis of idiopathic RBD according to the International Classification of Sleep Disorders-2 [2] were included. All patients granted written informed consent for this study. Exclusion criteria were having participated in our previous study where we showed the rates of EMG activity in 13 muscles in subjects with RBD [3]
Results
Patients were seven men and four women with a mean age of 67.7 ± 5.5 (range 54–77) years and a mean reported RBD duration of 5.4 ± 4.4 (range 1–16) years. All patients were right-handed. PSG measures are shown in Table 1. In this study, a total of 17,848 REM sleep 3-s mini-epochs free of artifacts were scored according the presence of phasic EMG activity and detection of motor and vocal events.
Discussion
In a previous study we showed that simultaneous EMG recording of the mentalis, flexor digitorum superficialis and extensor digitorum brevis muscles (the SINBAR EMG montage) detected the highest rates of REM sleep phasic EMG activity in subjects with RBD (3). Here, we aimed to evaluate the usefulness of the already defined five muscle SINBAR EMG montage to detect the behavioral motor and vocal events displayed by RBD subjects.
In the present study, based on detailed EMG and audiovisual
Conflicts of Interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: doi:10.1016/j.sleep.2010.04.021.
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Both authors contributed equally to this work.