Subjective oropharyngeal symptoms for abnormal swallowing in Japanese patients with obstructive sleep apnea syndrome: a descriptive questionnaire study.

OBJECTIVES: This study aimed to investigate the prevalence of clinical symptoms related to abnormal swallowing in a large sample of obstructive sleep apnea syndrome (OSAS) patients. METHODS: Oropharyngeal symptoms for abnormal swallowing were assessed by a self-administered questionnaire in 507 consecutive patients (females: 65, males: 442; mean age: 49.6 ± 12.6 years old) with clinical symptoms of OSAS, enrolled for cardiorespiratory evaluation. RESULTS: Overall, 16.2% of patients (82/507) had at least one symptom for abnormal swallowing and 6.3% (32/507) had two or more symptoms. The most frequent symptom was difficulty with coughing up phlegm during or after a meal (8.3%). Demographic, sleep, and clinical variables did not differ between the patients with and without abnormal symptoms. CONCLUSIONS: The results of the current study showed that 16% of middle-aged OSAS patients reported pharyngeal symptoms related to abnormal swallowing, regardless of the severity of OSAS.

Negative association between self-reported jaw symptoms and apnea-hypopnea index in patients with symptoms of obstructive sleep apnea syndrome: a pilot study.

OBJECTIVES: Prior to oral appliance therapy for snoring and obstructive sleep apnea syndrome (OSAS), patients are screened for jaw symptoms (e.g., pain). However, the presence of jaw symptoms in a large spectrum of OSAS patients remains unknown. This study aimed to assess the distribution of subjective jaw symptoms in patients with symptoms of OSAS. METHODS: Five hundred and eleven consecutive patients (66 female, 445 male; mean age 49.6 ± 12.6 years) with clinical symptoms of OSAS were enrolled for cardiorespiratory evaluation. Self-administered questionnaires were used to assess jaw symptoms, tooth grinding and clenching during sleep, morning oral dryness, morning heartburn sensation, and pain in the neck and back. RESULTS: The mean apnea-hypopnea (AHI) index was 32.5 ± 30.6 per hour of sleep. Nineteen percent of patients (n = 96) reported at least one jaw symptom. The presence of jaw symptoms was more frequently reported by patients with AHI less than 15 (25 %) than those with AHI of 15 and more (15 %, p = 0.012). In the crude analyses, jaw symptoms were associated with tooth grinding, tooth clenching, morning oral dryness, morning heartburn sensation, and neck/back pain. Multiple logistic regression analysis confirmed that jaw symptoms were associated with AHI less than 15 (odds ratio (OR) 1.99, p = 0.009), tooth clenching (OR 1.79, p = 0.006), morning oral dryness (OR 2.17, p = 0.02), and neck/back pain (OR 1.99, p = 0.005). CONCLUSIONS: Jaw symptoms can be found in 19 % of patients with symptoms of OSAS and are more frequently reported in patients with lower AHI, a patient population for whom oral appliances are often prescribed.

Relationships between respiratory and oromotor events differ between motor phenotypes in patients with obstructive sleep apnea.

Purpose: The present study investigated the relationship between sleep bruxism (SB) and obstructive sleep apnea (OSA) in relation to the sleep architecture. Methods: We conducted a cross-sectional study. Polysomnographic recordings were performed on 36 patients. Sleep, respiratory, and oromotor variables, such as rhythmic masticatory muscle activity (RMMA) and non-specific masticatory muscle activity (NSMA), were compared between OSA patients with or without SB. A correlation analysis of the frequency of respiratory and oromotor events in NREM and REM sleep was performed. The frequency of oromotor events following respiratory events was also assessed. Results: The proportion of REM sleep was higher in OSA patients with SB than in those without SB (p = 0.02). The apnea-hypopnea index (AHI) did not significantly differ between the two groups; however, AHI was approximately 8-fold lower during REM sleep in OSA patients with SB (p = 0.01) and the arousal threshold was also lower (p = 0.04). Although the RMMA index was higher in OSA patients with than in those without SB (p < 0.01), the NSMA index did not significantly differ. The percentage of RMMA following respiratory events was significantly higher in OSA patients with than in those without SB, whereas that of NSMA did not significantly differ. The frequency of oromotor events throughout the whole night positively correlated with AHI. However, regardless of the sleep state, AHI did not correlate with the RMMA index, but positively correlated with the NSMA index. Conclusion: In consideration of the limitations of the present study, the results obtained indicate that OSA patients with SB have a unique phenotype of OSA and also emphasize the distinct relationship of respiratory events with RMMA and NSMA.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020.

The prevalence of sleep disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared in order to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Because sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Multimodal Telemonitoring for Weight Reduction in Patients With Sleep Apnea: A Randomized Controlled Trial.

BACKGROUND: Telemonitoring the use of CPAP devices and remote feedback on device data effectively optimizes CPAP adherence in patients with OSA. RESEARCH QUESTION: Can expanding the scope of telemonitoring and remote feedback to body weight (BW), BP, and physical activity enhance efforts for BW reduction in Patients with OSA receiving CPAP? STUDY DESIGN AND METHODS: Participants were recruited from patients at 16 sleep centers in Japan with OSA and obesity who were receiving CPAP therapy. Obesity was defined as a BMI of ≥ 25 kg/m2, based on Japanese obesity guidelines. Implementation of CPAP telemonitoring was enhanced with electronic scales, BP monitors, and pedometers that could transmit data from devices wirelessly. Participants were randomized to the multimodal telemonitoring group or the usual CPAP telemonitoring group and were followed up for 6 months. Attending physicians provided monthly telephone feedback calls to the usual CPAP telemonitoring group on CPAP data obtained remotely. In the multimodal telemonitoring group, physicians additionally encouraged participants to reduce their BW, after sharing the remotely obtained data on BW, BP, and step count. The primary outcome was set as ≥ 3% BW reduction from baseline. RESULTS: One hundred sixty-eight participants (BMI, 31.7 ± 4.9 kg/m2) completed the study, and ≥ 3% BW reduction occurred in 33 of 84 participants (39.3%) and 21 of 84 participants (25.0%) in the multimodal telemonitoring and usual CPAP telemonitoring groups, respectively (P = .047). Whereas no significant differences were found between the two groups in the change in office and home BP, daily step counts during the study period were significantly higher in the multimodal telemonitoring group than in the usual CPAP telemonitoring group (4,767 steps/d [interquartile range (IQR), 2,864-6,617 steps/d] vs 3,592 steps/d [IQR, 2,117-5,383 steps/d]; P = .02) INTERPRETATION: Multimodal telemonitoring may enhance BW reduction efforts in patients with OSA and obesity. TRIAL REGISTRY: UMIN Clinical Trials Registry; No.: UMIN000033607; URL: www.umin.ac.jp/ctr/index.htm.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020.

The prevalence of sleep-disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Since sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

A Randomized Controlled Trial of Telemedicine for Long-Term Sleep Apnea Continuous Positive Airway Pressure Management.

Rationale: The effects of telemedicine on adherence in patients with obstructive sleep apnea with long-term continuous positive airway pressure (CPAP) use have never been investigated.Objectives: To examine effects of a telemedicine intervention on adherence in long-term CPAP users.Methods: In a prospective, randomized, multicenter noninferiority trial conducted in 17 sleep centers across Japan, patients who had used CPAP for >3 months and were receiving face-to-face follow-up by physicians every 1 or 2 months were randomized by a coordinating center in a blind manner to the following three groups: 1) follow-up every 3 months accompanied by a monthly telemedicine intervention (telemedicine group: TM-group), 2) follow-up every 3 months (3-month group: 3M-group), or 3) monthly follow-up (1-month group: 1M-group). Each group was followed up for 6 months. The change in percentage of days with ≥4 h/night of CPAP use from baseline to the end of the study period was evaluated. A decline of ≥5% from baseline was considered deterioration of adherence. Noninferiority of TM- and 3M-groups compared with the 1M-group according to the number of patients with deterioration of adherence was evaluated with the Farrington and Manning test (noninferiority margin 15%).Results: A total of 483 patients were analyzed (median duration of CPAP use, 29 [interquartile range, 12-71] mo), and deterioration of adherence was found in 41 of 161 (25.5%), 55 of 166 (33.1%), and 35 of 156 (22.4%) patients in the TM-, 3M-, and 1M-groups, respectively. The noninferiority of the TM-group compared with the 1M-group was verified (difference in percentage of patients with adherence deterioration, 3.0%; 95% confidence interval [CI], -4.8% to 10.9%; P < 0.01). Conversely, the 3M-group did not show noninferiority to the 1M-group (percentage difference, 10.7%; 95% CI, 2.6% to 18.8%; P = 0.19). In the stratified analysis, adherence in TM- and 1M-group patients with poor adherence at baseline improved (TM: 45.8% ± 18.2% to 57.3% ± 24.4%; P < 0.01; 1M: 43.1% ± 18.5% to 53.6% ± 24.3%; P < 0.01), whereas that of the 3M-group did not (39.3% ± 20.8% to 39.8% ± 24.8%; P = 0.84).Conclusions: Intensive telemedicine support could help to optimize CPAP adherence even after long-term CPAP use.Clinical trial registered with www.umin.ac.jp/ctr/index.htm (trial number: UMIN000023118).

Simple four-variable screening tool for identification of patients with sleep-disordered breathing.

OBJECTIVES: To aid in the identification of patients with moderate-to-severe sleep-disordered breathing (SDB), we developed and validated a simple screening tool applicable to both clinical and community settings. METHODS: Logistic regression analysis was used to develop an integer-based risk scoring system. The participants in this derivation study included 132 patients visiting one of 2 hospitals in Japan, and 175 residents of a rural town. The participants in the present validation study included 308 employees of a company in Japan who were undergoing a health check. RESULTS: The screening tool consisted of only 4 variables: sex, blood pressure level, body mass index, and self-reported snoring. This tool (screening score) gave an area under the receiver operating characteristic curve (ROC) of 0.90, sensitivity of 0.93, and specificity of 0.66, using a cutoff point of 11. Predicted and observed prevalence proportions in the validation dataset were in close agreement across the entire spectrum of risk scores. In the validation dataset, the area under the ROC for moderate-to-severe SDB and severe SDB were 0.78 and 0.85, respectively. The diagnostic performance of this tool did not significantly differ from that of previous, more complex tools. CONCLUSION: These findings suggest that our screening scoring system is a valid tool for the identification and assessment of moderate-to-severe SDB. With knowledge of only 4 easily ascertainable variables, which are routinely checked during daily clinical practice or mass health screening, moderate-to-severe SDB can be easily detected in clinical and public health settings.

[A case of severe obstructive sleep apnea mimicking REM sleep behavior disorder].

The rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by dream-enacting behaviors related to the loss of the normal generalized skeletal muscle atonia during REM sleep, and shows REM sleep without atonia (RWA) during polysomnography (PSG). Patients with idiopathic RBD have been known to have a siginificantly increased risk of developing one of the α-synucleiopathies later in life, therefore the diagnosis of RBD is very important and must be dealt with carefully. A 51-year-old man was identified presenting dream-enacting behaviors and unpleasant dreams suggesting the diagnosis of RBD, in addition to snoring and excessive daytime sleepiness. Attended video-PSG excluded RBD showing REM sleep with atonia and without increased phasic EMG activity, and diagnosed with severe obstructive sleep apnea (OSA) with an apnea-hypopnea index of 30.1 demonstrating that the reported abnormal sleep behaviors occurred only during respiratory event-induced arousals. Continuous positive airway pressure therapy eliminated the abnormal behaviors, unpleasant dreams, snoring and daytime hypersomnolence. This case shows that severe OSA mimic the symptoms of RBD and that attended video-PSG is necessary to establish the diagnosis of RBD, and identify or exclude other causes of dream-enacting behaviors.

[Noninvasive positive pressure ventilation in patients with acute exacerbations of pulmonary tuberculosis sequelae].

To clarify whether noninvasive positive pressure ventilation (NPPV) is effective in patients with acute exacerbations of pulmonary tuberculosis sequelae (PTS), 50 PTS patients (66 episodes) without long-term domiciliary noninvasive ventilation were studied, retrospectively. The average values (SD) of their pulmonary function tests and arterial blood gases were as follows; %predicted VC = 31.4 (8.4)%, pH = 7.29 (0.06), PaCO2 = 91.8 (19.7) mmHg, and PaO2 = 64.2 (20.3) mmHg. The probability of avoiding endotracheal intubation and recovering from an acute exacerbation with NPPV (NPPV success rate) was 92% as a whole. NPPV success rates according to the causes of deterioration were as follows; 96% in 26 episodes with only a simple right heart failure, 93% in 29 episodes with airway infectious diseases, 75% in eight episodes with pneumonia and/or acute respiratory distress syndrome. Moreover, the NPPV success rate of eight episodes in coma or semicoma was 88%. Most patients were treated in respiratory wards rather than intensive care units. Out of 46 patients who recovered from an acute exacerbation, 41 finally received domiciliary NPPV. In facilities where staff are well-trained for an acute NPPV, patients with exacerbations of PTS can be treated as successfully with NPPV as patients with COPD.

The Importance of Stabilizing PaCO2 during Long-term Non-invasive Ventilation in Subjects with COPD.

OBJECTIVE: In subjects with chronic obstructive pulmonary disease (COPD), the effect of partial pressure of CO2 (PaCO2) alterations during long-term non-invasive ventilation (NIV) on continuance remains uncertain. We herein investigated the utility of PaCO2 stability during long-term NIV as a prognostic outcome. METHODS: We retrospectively assessed data from 54 subjects with COPD who received long-term NIV. The annual alteration in PaCO2 during NIV was determined using a simple linear regression method for each subject who had at least two 6-month intervals of PaCO2 data. Annual alterations in PaCO2 during long-term NIV and probable confounders were examined, and long-term NIV discontinuation was the major outcome. RESULTS: Data from 37 subjects who met the criteria were analyzed. PaCO2 during long-term NIV increased slightly in 19 subjects (group 1, <2 mm Hg/y), and increased greatly in 18 subjects (group 2, >2 mmHg/y). In the multivariate modality model, smaller annual alterations in PaCO2 (p=0.009) and lower PaCO2 6 months after the start of long-term NIV (6 m-PaCO2) (p=0.03) were associated with a significantly higher probability of continuing NIV. The 2- and 5-year probabilities of continuing NIV were 89% and 66% for group 1 and 78% and 32% for group 2, respectively. CONCLUSION: A lower 6 m-PaCO2 and a lower annual alteration of PaCO2 during long-term NIV are significant predictive variables for patients with COPD.

Effects of obstructive sleep apnea syndrome on serum aminotransferase levels in obese patients.

PURPOSE: Obesity has been associated with obstructive sleep apnea and hepatic steatosis. We investigated the effects of obstructive sleep apnea and treatment with nasal continuous positive airway pressure (CPAP) on serum aminotransferase levels in obese patients. METHODS: We studied 40 obese men with obstructive sleep apnea syndrome. None had hepatitis B antigen or C antibody, autoimmune disease, or an excessive intake of alcohol. Serum levels of aspartate aminotransferase, alanine aminotransferase, triglyceride, glucose, insulin, and leptin were determined in the afternoon and in the morning immediately after sleep, before and after nasal CPAP treatment. RESULTS: Aminotransferase levels were abnormal in 35% (n = 14) of patients. Before treatment, mean (+/- SD) aspartate aminotransferase levels were higher in the morning than in the previous afternoon (presleep, 34 +/- 20 IU/L; postsleep, 39 +/- 28 IU/L; P = 0.006). The overnight mean increases in aminotransferase levels were less marked after the first night of nasal CPAP treatment (aspartate aminotransferase: from 6 +/- 11 IU/L to 2 +/- 6 IU/L, P = 0.0003; alanine aminotransferase: from 5 +/- 9 IU/L to 2 +/- 6 IU/L, P = 0.006). Leptin levels (n = 23) decreased significantly after treatment (P = 0.0002), whereas insulin resistance (calculated by the homeostasis model assessment method) and triglyceride levels were unchanged. Improvements in aspartate and alanine aminotransferase levels were maintained after 1 and 6 months of nasal CPAP treatment. CONCLUSION: Nasal CPAP therapy may have beneficial effects on serum aminotransferase abnormalities in obese patients who have obstructive sleep apnea.

Corrected QT dispersion and cardiac sympathetic function in patients with obstructive sleep apnea-hypopnea syndrome.

STUDY OBJECTIVES: Hypoxemia increases corrected QT dispersion (QTcD), which is the difference between the maximum and minimum QT intervals and is a strong risk factor for cardiovascular mortality. The aim of this study was to investigate the QTcD in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), and the relationship between the QTcD and (123)I-metaiodobenzylguanidine (MIBG) cardiac imaging, which reflects cardiac sympathetic activity. SETTING: A university hospital. PATIENTS: Forty-eight OSAHS patients without cardiac diseases (mean [+/- SD] age, 45.9 +/- 10.8 years; apnea-hypopnea index [AHI] 51.9 +/- 18.5 events per hour) who underwent polysomnography before treatment and on the first night of nasal continuous positive airway pressure (nCPAP) treatment. METHODS: Before and after nCPAP treatment was started, we measured the QTcD with computer software, before, during, and after sleep, as well as the washout rate of the MIBG administered for cardiac imaging. As a control, QTcD was also measured in the morning from 26 healthy subjects. RESULTS: Before treatment, the mean QTcD during sleep (65.0 +/- 14.6 ms) was greater than that before sleep (57.0 +/- 13.5 ms; p < 0.0001). Meanwhile, after 1 night of nCPAP therapy, the QTcD during sleep (50.6 +/- 11.4 ms) decreased from that before treatment (p < 0.0001) and was smaller than the QTcD before sleep (56.2 +/- 13.3 ms; p = 0.003). Before treatment, the QTcD during sleep correlated with the AHI (r = 0.38; p = 0.009) and the percentage of time that SaO(2) was < 90% (SaO(2) < 90% time) [r = 0.34; p = 0.018]. The QTcD did not correlate with the body mass index or the washout rate of MIBG. However, the washout rate of MIBG correlated with the AHI and the SaO(2) < 90% time. CONCLUSIONS: Nocturnal QTcD is increased in OSAHS patients but is decreased by nCPAP therapy independently of cardiac sympathetic function.

The importance of controlling PaCO2 throughout long-term noninvasive ventilation.

BACKGROUND: The significance of changes in P(aCO2) during long-term noninvasive ventilation (NIV) on prognosis remains unclear. We aimed to clarify whether stabilizing P(aCO2) during NIV had a favorable prognostic effect. METHODS: Data from 190 subjects with restrictive thoracic disease and who received long-term NIV were studied retrospectively. The annual change in P(aCO2) during NIV was determined using a simple linear regression method for each subject who had at least 4 6-month intervals of P(aCO2) data. Annual changes in P(aCO2) during long-term NIV and possible confounders were analyzed with discontinuation of long-term NIV as the main outcome. RESULTS: One hundred and twenty-five subjects who had > 4 6-month intervals of P(aCO2) data were included in the study. P(aCO2) during long-term NIV decreased in 41 subjects (group 1; < 0 mm Hg/y), increased slightly in 42 subjects (group 2; between 0 and 1.85 mm Hg/y), and increased significantly in 42 subjects (group 3; > 1.85 mm Hg/y). Smaller annual changes in P(aCO2) (P < .001) and a control ventilator mode (P = .008) were associated with a significantly higher probability of continuing NIV, compared with decreased P(aCO2) 3-6 months after the start of long-term NIV (P = .11). The 10-y probability of continuing NIV was 69% in group 1, 39% in group 2, and 12% in group 3. CONCLUSIONS: A decrease in the annual change of P(aCO2) during long-term NIV was shown to be a significantly prognostically favorable factor. Efforts to reduce P(aCO2) should be made if P(aCO2) increases at a greater rate during long-term NIV.

The impact of obstructive sleep apnea syndrome on nocturnal urine production in older men with nocturia.

OBJECTIVE: To investigate the impact of obstructive sleep apnea syndrome (OSAS) on night-time secretion of brain natriuretic peptide (BNP) and antidiuretic hormone (ADH) in older men with nocturia accompanied by nocturnal polyuria. MATERIALS AND METHODS: One hundred six men with nocturia aged ≥ 60 years underwent full-night polysomnography to determine whether they had OSAS. Blood count, standard chemistry panel, BNP, urinary ADH, urinary creatinine (u-Cre), and urinary osmolarity were measured at 6:00 AM, and a frequency volume chart was recorded on the same day that polysomnography was performed. RESULTS: We evaluated 83 patients after excluding 18 with mild OSAS and 5 with nocturnal polyuria index <0.35. Participants with OSAS had higher apnea-hypopnea index (P < .0001) than those without OSAS. Body mass index and systolic blood pressure were higher in OSAS patients than those in the control group. BNP was higher in the OSAS patients than in the control patients (48.6 ± 41.4 vs 30.7 ± 31.5; P = .0006). On urinalysis, OSAS patients showed higher urinary sodium and u-Cre secretion than controls (24.7 ± 11.3 vs 16.2 ± 5.1; P <.0001). Urine osmolarity was also higher in OSAS patients than in the control patients (616 ± 172 vs 516 ± 174; P = .0285). There was no significant difference in urinary ADH and u-Cre (6.7 ± 10.4 vs 6.8 ± 7.8; P = .3617) between the 2 groups. CONCLUSION: Our results indicated that older men with nocturnal polyuria and OSAS did not compensate their fluid imbalance presented with decreased secretion of ADH but increased BNP level.

Responsiveness of jaw motor activation to arousals during sleep in patients with obstructive sleep apnea syndrome.

OBJECTIVES: We aimed to characterize the association between jaw muscle contractions and respiratory events in patients with obstructive sleep apnea syndrome (OSAS) and to investigate the responsiveness of the contractions to respiratory events in comparison with that of leg muscles in terms of arousal types and sleep states. METHODS: Polysomnographic (PSG) recordings were performed in 19 OSAS patients (F/M: 2/17; 53.1 ± 13.7 years; AHI: 31.8 ± 19.9/h) with no concomitant sleep bruxism or other sleep-related movement disorders. Muscle contractions of unilateral masseter (MAS) and anterior tibialis (AT) muscles were scored during sleep in association with graded arousals (microarousals and awakenings) related or unrelated to apneahypopnea events. RESULTS: Arousals were scored for 68.2% and 52.3% of respiratory events during light NREM and REM sleep, respectively. Respiratory events with arousals were associated with longer event duration and/or larger transient oxygen desaturation than those without (ANOVAs: p < 0.05). Median response rates of MAS events to respiratory events were 32.1% and 18.9% during NREM and REM sleep. During two sleep states, MAS muscle was rarely activated after respiratory events without arousals, while its response rate increased significantly in association with the duration of arousals (Friedman tests: p < 0.001). A similar response pattern was found for AT muscle. Motor responsiveness of the two muscles to arousals after respiratory events did not differ from responsiveness to spontaneous arousals in two sleep stages. CONCLUSION: In patients with OSAS, the contractions of MAS and AT muscles after respiratory events can be nonspecific motor phenomena, dependent on the duration of arousals rather than the occurrence of respiratory events.