Elsevier

Sleep Medicine

Volume 12, Issue 3, March 2011, Pages 284-288
Sleep Medicine

Original Article
Usefulness of the SINBAR electromyographic montage to detect the motor and vocal manifestations occurring in REM sleep behavior disorder

https://doi.org/10.1016/j.sleep.2010.04.021Get rights and content

Abstract

Objective

In a previous study we showed that simultaneous electromyographic (EMG) recording of the mentalis, flexor digitorum superficialis and extensor digitorum brevis (SINBAR EMG montage) detected the highest rates of rapid eye movement (REM) sleep phasic EMG activity in subjects with REM sleep behavior disorder (RBD). As a next step, in the present study we evaluated the usefulness of the SINBAR EMG montage to detect the movements and vocalizations occurring in RBD.

Methods

Polysomnographic studies with synchronized audiovisual monitoring of 11 patients with idiopathic RBD were analyzed. Phasic EMG activity in REM sleep was scored and quantified in 3-s mini-epochs while the video was reviewed to detect motor events and vocalizations.

Results

A total of 64.8% (11,562 out of 17,848) of all mini-epochs contained phasic EMG activity, whereas 28.8% (5135 out of 17,848) contained movements or vocalizations. Using the SINBAR EMG montage, 94.4% of the mini-epochs containing behavioral events were linked to phasic EMG activity. The sensitivity of the SINBAR EMG montage was 94.4%, specificity was 47.2%, negative predictive value was 95.4% and positive predictive value was 41.9%. Isolated EMG recording of the mentalis did not show phasic EMG activity in 35.5% of the behavioral events seen in the video.

Conclusions

The SINBAR EMG montage is a useful approach for the diagnosis of RBD showing that simultaneous EMG recording of the mentalis, flexor digitorum superficialis and extensor digitorum brevis muscles detected the majority (94.4%) of the motor and vocal manifestations occurring in RBD. For clinical purposes, this means that it is efficient to screen the video when increased phasic EMG activity is seen on the polysomnography.

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.

Section snippets

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.

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