Actual state of the diurnal masseteric electromyogram: Differences between awareness and non-awareness of awake bruxism.

PURPOSE: This study aimed to elucidate the relationship between diurnal masseter muscle activity and awareness of diurnal awake bruxism (d-AB) by conducting a comparative analysis of electromyographic (EMG) data from individuals with and without awareness of diurnal awake bruxism (d-AB), utilizing EMG data gathered from multiple subjects. METHODS: Unilateral masseter electromyography (EMG) recordings were performed during the daytime using an ultraminiature wearable EMG device. A total of 119 participants (59 with awareness of diurnal tooth clenching [d-TC] and 60 without awareness of d-TC) were included. Waveforms longer than 0.25 s with the two amplitude conditions, exceeding twice the baseline and >5% of maximum voluntary clenching, were extracted. In addition, the number of bursts and episodes (groups of bursts), burst duration, and burst peak amplitude were calculated for each participant. RESULTS: There were no significant differences in the EMG parameters between the groups with and without awareness of d-TC. Additionally, the frequency distribution of the number of EMG waveforms exhibited wide ranges and substantial overlap between the two groups. CONCLUSIONS: The variability in the number of bursts and episodes, burst peak amplitude, and burst duration among subjects suggests the need for an objective classification of d-AB severity based on EMG values. The absence of significant differences and large overlap in frequency distributions between the groups with and without awareness of d-TC indicate difficulty in predicting muscle activity solely based on awareness of d-AB.

Examination of the relationship between masseter muscle activity during sleep and wakefulness measured by using a wearable electromyographic device.

Purpose This study aimed to measure masseter muscle activity throughout the day in outpatients suspected of having awake bruxism (AB) and/or sleep bruxism (SB) and examine the relationship between AB and SB by comparing muscle activity during daytime wakefulness and nighttime sleep.Methods Fifty outpatients with suspected SB and/or AB participated in this study. A single-channel wearable electromyogram (EMG) device was used for EMG recording. The selected EMG bursts were divided into bursts during sleep (S-bursts) and bursts during awake state (A-bursts). The number of bursts per hour, average burst duration, and ratio of burst peak value to maximum voluntary contraction were calculated for both the S- and A-bursts. These values of the S- and A-bursts were then compared, and the correlations between them were analyzed. Additionally, the ratios of phasic and tonic bursts in the S- and A-bursts were compared.Results The number of bursts per hour was significantly higher for A-bursts than for S-bursts. No significant correlation was found between the numbers of S- and A-bursts. The ratio of phasic bursts was large and that of tonic bursts was small in both the S- and A-bursts. A comparison of the S- and A-bursts showed that the S-bursts had a significantly lower ratio of phasic bursts and higher ratio of tonic bursts than the A-bursts.Conclusions The number of masseteric EMG bursts during wakefulness did not show any association with that during sleep. It became clear that sustained muscle activity was not dominant in AB.

Portable and wearable electromyographic devices for the assessment of sleep bruxism and awake bruxism: A literature review.

OBJECTIVE: The current state of portable/wearable electromyographic (EMG) devices for assessment of bruxism was reviewed. METHODS: A search of full-text articles relevant to portable/wearable EMG devices capable of being used at home was performed. The data source used was MEDLINE via PubMed from January 1970 to July 2019. RESULTS: There were nine kinds of wearable EMG devices capable of being used under unrestrained conditions. Ultra-miniaturized wearable EMG devices with a level of performance equivalent to that of conventional stationary EMG devices have been developed and are being used during sleep and in the daytime. The devices have a high level of diagnostic accuracy for sleep bruxism. A definite cut-off value for awake bruxism has not been established. DISCUSSION: Assessment of sleep bruxism with a high level of accuracy can be performed using a portable/wearable EMG device. However, a definite cut-off value is required for assessment of awake bruxism.

Comparison of the occurrence of sleep bruxism under accustomed conditions at home and under polysomnography conditions in a sleep laboratory.

PURPOSE: We aimed to clarify the relationship between the number of sleep bruxism (SB) bursts at home and in a laboratory equipped with polysomnography with audio-video recording (PSG-AV). We applied an identical single-channel wearable electromyography (EMG) device for both types of SB burst scorings. METHODS: The subjects were 20 healthy student volunteers (12 men and 8 women; mean age, 21.9 years) who were clinically diagnosed with bruxism based on the criteria set forth by the International Classification of Sleep Disorders (ICSD-2). We used a wearable EMG device attached to the masseteric area (the FLA-500-SD [FLA]), for scoring SB bursts at home and in the laboratory. PSG-AV was set within the laboratory environment as well. The mean interval for both sleep studies was 28.8 days. EMG bursts with amplitudes greater than twice the baseline amplitude and with durations of longer than 0.25 s were selected. EMG bursts with amplitudes ≥5% MVC (maximum voluntary contraction), ≥10% MVC, and ≥20% MVC were selected as well. A cluster of bursts was defined as an episode. RESULTS: In all the conditions for selecting EMG bursts specified above, the number of SB bursts and episodes recorded under laboratory conditions was statistically significantly smaller than that recorded at home. There were no statistically significant differences between the data obtained on the first and second recording days. CONCLUSION: The results of this study suggest that the unfamiliar environment of a sleep laboratory equipped with PSG-AV affects the emergence of SB as compared with home conditions.

Minimum measurement time of masseteric electromyogram required for assessment of awake bruxism during the daytime.

Objective: Assessments of diurnal awake bruxism (d-AB) using masseteric electromyogram (EMG) during various lengths of measurement time within a day were examined as the first step of research to clarify the minimum measurement time required for assessment of d-AB by subject.Methods: Subjects were 33 outpatients. Assessment of d-AB by EMG during partial measurement time (PMT) with durations ranging from 30 minutes to 6 hours was compared with that during total measurement time (TMT) used as the reference standard.Results: No significant difference was found between TMT data and PMT data. There were significant correlations in all combinations between TMT data and PMT data. Accuracy was 0.909 or more for 2.5 hours or longer.Discussion: The results suggest that the tendency of daytime muscle activity in 1 day can be assessed even by using masseteric EMG data obtained during a relatively short measurement time.

A case of diabetic ketoacidosis in a patient with COVID-19 and newly diagnosed type 1 diabetes.

To improve severe ketoacidosis with COVID-19, insulin treatment, invasive mechanical ventilation therapy, and continuous hemodiafiltration with sodium bicarbonate infusion were effective.

Crucial role of leaky initiation of uORF3 in the downregulation of HNT1 by ER stress.

eIF2α phosphorylation-mediated translational regulation is crucial for global repression of translation by various stresses, including the unfolded protein response (UPR) in eukaryotes. Although translational control during UPR has not been extensively investigated in S. cerevisiae, Hac1-mediated production of long transcripts containing uORFs was shown to repress the translation of histidine triad nucleotide-binding 1 (HNT1) mRNA. The present study showed that uORF3 is required for HNT1 expression, as well as down-regulating HNT1 translation. Translation initiation by uORF3 is inefficient, with uORF3 having a strong Kozak sequence efficiently repressing the translation of HNT1. We propose that leaky scanning of uORF3 is responsible for the downregulation of HNT1 during UPR.

Quantitative analyses of jaw-opening muscle activity during the active phase of jaw-closing muscles in sleep bruxism.

Rhythmic masticatory muscle activity (RMMA), which is defined as three or more consecutive phasic bursts, accounts for a large part of sleep bruxism (SB). RMMA is thought to be characterized by co-contraction, a jaw muscle activity in which jaw-opening muscles contract during the active phase of jaw-closing muscles, which is different from that during mastication. However, there has been limited information about co-contraction. The aim of the present study was to clarify the amplitudes and patterns of jaw-opening muscle activity during the active phase of jaw-closing muscles in RMMA. Data from 14 healthy volunteers with bruxism, which was diagnosed by using polysomnographic recording with audio-video, were analysed. RMMA with electromyographic amplitudes of more than two times the baseline amplitude was selected. From the selected RMMA, burst groups consisting of five or more consecutive phasic bursts, including tonic bursts, were selected for analyses. Electromyographic activities during gum chewing were also recorded before sleeping. The minimum, maximum and average value of the amplitudes of jaw-opening muscle activity during the active phase of jaw-closing muscles were calculated. Jaw-opening muscle activity during the active phase of jaw-closing muscles in RMMA was closer to the baseline than that in gum chewing. The minimum, maximum and average values of amplitudes of jaw-opening muscle activity during the phase were significantly smaller than those of gum chewing. Contrary to our hypothesis prior to the study, the obtained results suggested that the pattern of electromyogram activity of jaw-opening and jaw-closing muscles in RMMA was not necessarily co-contraction.

Validity of single-channel masseteric electromyography by using an ultraminiature wearable electromyographic device for diagnosis of sleep bruxism.

PURPOSE: The purpose of this study was to clarify the validity of assessment of sleep bruxism (SB) by using single-channel electromyogram (EMG) and a cut-off value with optimum sensitivity and specificity. METHODS: The subjects were twenty volunteers with clinical diagnosis of SB. Assessment by masseteric EMG data only by using a wearable EMG was compared with reference standard assessment by masseteric EMG data using polysomnography with audio-visual recording (PSG-AV). From EMG activities recorded by single-channel EMG, bursts of more than two times the baseline amplitude with a duration of 0.25s or more were selected by a burst unit (EMG-burst-all). Furthermore, from EMG-burst-all, bursts that were more than 5-20% of the maximum voluntary contraction value (EMG-burst-5%, EMG-burst-10%, EMG-burst-20%) were selected. By an episode unit, phasic, tonic, and mixed episodes were selected by single-channel EMG (EMG-episodes). Among the EMG-episodes, further, reference standard episodes of SB (PSG-episodes) were selected by PSG-AV assessment. RESULTS: Sixteen subjects were diagnosed as bruxers based on PSG-AV (PSG-episodes/h >2). By a burst unit and an episode unit, there were significant correlations between assessment variables of SB by single-channel EMG and PSG-AV except for EMG-burst-20%/h. When the cut-off value in EMG-episodes/h was 5.5/h for sleep bruxers, both sensitivity and specificity were 100%. As for variables by a burst unit, EMG-burst-all/h and EMG-burst-5% had higher values of sensitivity and specificity. CONCLUSIONS: The results suggested that single-channel EMG is valid for diagnosis of SB if a cut-off value that is appropriate for single-channel EMG is used.