Case Study: Imaging of Apnea Termination in a Patient with Obstructive Sleep Apnea during Natural Sleep.
ABSTRACT: A 55-year-old woman who presented to the sleep clinic with severe sleep apnea (OSA) (apnea-hypopnea index [AHI] 62) and excessive somnolence (Epworth Sleepiness Scale score 18/24), was imaged with MRI using the Spatial Modulation of Magnetization tagging sequence awake and asleep to visualize upper airway tissue movement. Awake quiet breathing resulted in minimal movement of upper airway tissues. Asleep sequences taken during airway opening post-apnea demonstrated neck extension, mandibular advancement, and widespread tongue deformation accompanying contraction of genioglossus. At the end of the asleep image sequence, the nasopharyngeal airway had a cross-sectional area larger than during quiet breathing awake and there was antero-lateral movement in the lateral walls. In conclusion, the airway responds to apnea by widespread contraction of the genioglossus, followed by mandibular advancement and neck extension. All these maneuvers stabilize and open the airway.
Project description:Maxillomandibular advancement (MMA) is effective for the treatment of obstructive sleep apnea (OSA). In previous studies, the airway was increased in the anteroposterior and transverse dimensions after MMA. However, the effect of the opposite of mandibular movement (mandibular setback) on the airway is still controversial. Mandibular setback surgery has been suggested to be one of the risk factors in the development of sleep apnea. Previous studies have found that mandibular setback surgery could reduce the total airway volume and posterior airway space significantly in both the one-jaw and two-jaw surgery groups. However, a direct cause-and-effect relationship between the mandibular setback and development of sleep apnea has not been clearly established. Moreover, there are only a few reported cases of postoperative OSA development after mandibular setback surgery. These findings may be attributed to a fundamental difference in demographic variables such as age, sex, and body mass index (BMI) between patients with mandibular prognathism and patients with OSA. Another possibility is that the site of obstruction or pattern of obstruction may be different between the awake and sleep status in patients with OSA and mandibular prognathism. In a case-controlled study, information including the BMI and other presurgical conditions potentially related to OSA should be considered when evaluating the airway. In conclusion, the preoperative evaluation and management of co-morbid conditions would be essential for the prevention of OSA after mandibular setback surgery despite its low incidence.
Project description:The genioglossus is a major upper airway dilator muscle thought to be important in obstructive sleep apnea pathogenesis. Aging is a risk factor for obstructive sleep apnea although the mechanisms are unclear and the effects of aging on motor unit remodeled in the genioglossus remains unknown. To assess possible changes associated with aging we compared quantitative parameters related to motor unit potential morphology derived from EMG signals in a sample of older (n?=?11; >55 years) versus younger (n?=?29; <55 years) adults. All data were recorded during quiet breathing with the subjects awake. Diagnostic sleep studies (Apnea Hypopnea Index) confirmed the presence or absence of obstructive sleep apnea. Genioglossus EMG signals were analyzed offline by automated software (DQEMG), which estimated a MUP template from each extracted motor unit potential train (MUPT) for both the selective concentric needle and concentric needle macro (CNMACRO) recorded EMG signals. 2074 MUPTs from 40 subjects (mean±95% CI; older AHI 19.6±9.9 events/hr versus younger AHI 30.1±6.1 events/hr) were extracted. MUPs detected in older adults were 32% longer in duration (14.7±0.5 ms versus 11.1±0.2 ms; P ?=? 0.05), with similar amplitudes (395.2±25.1 µV versus 394.6±13.7 µV). Amplitudes of CNMACRO MUPs detected in older adults were larger by 22% (62.7±6.5 µV versus 51.3±3.0 µV; P<0.05), with areas 24% larger (160.6±18.6 µV.ms versus 130.0±7.4 µV.ms; P<0.05) than those detected in younger adults. These results confirm that remodeled motor units are present in the genioglossus muscle of individuals above 55 years, which may have implications for OSA pathogenesis and aging related upper airway collapsibility.
Project description:STUDY OBJECTIVES: To characterize tongue and lateral upper airway movement and to image tongue deformation during mandibular advancement. DESIGN: Dynamic imaging study of a wide range of apnea hypopnea index (AHI), body mass index (BMI) subjects. SETTING: Not-for-profit research institute. PARTICIPANTS: 30 subjects (aged 31-69 y, AHI 0-75 events/h, BMI 17-39 kg/m(2)). INTERVENTIONS: Subjects were imaged using dynamic tagged magnetic resonance imaging during mandibular advancement. Tissue displacements were quantified with the harmonic phase technique. MEASUREMENTS AND RESULTS: Mean mandibular advancement was 5.6 ± 1.8 mm (mean ± standard deviation). This produced movement through a connection from the ramus of the mandible to the pharyngeal lateral walls in all subjects. In the sagittal plane, 3 patterns of posterior tongue deformation were seen with mandibular advancement-(A) en bloc anterior movement, (B) anterior movement of the oropharyngeal region, and (C) minimal anterior movement. Subjects with lower AHI were more likely to have en bloc movement (P = 0.04) than minimal movement. Antero-posterior elongation of the tongue increased with AHI (R = 0.461, P = 0.01). Mean anterior displacements of the posterior nasopharyngeal and oropharyngeal regions of the tongue were 20% ± 13% and 31% ± 17% of mandibular advancement. The posterior tongue compressed 1.1 ± 2.2 mm supero-inferiorly. CONCLUSIONS: Mandibular advancement has two mechanisms of action which increase airway size. In subjects with low AHI, the entire tongue moves forward. Mandibular advancement also produces lateral airway expansion via a direct connection between the lateral walls and the ramus of the mandible. CITATION: Brown EC; Cheng S; McKenzie DK; Butler JE; Gandevia SC; Bilston LE. Tongue and lateral upper airway movement with mandibular advancement. SLEEP 2013;36(3):397-404.
Project description:Twenty healthy subjects (10 males, age 28±5 years [mean ± SD]) lay supine, awake, with the head in a neutral position. Ventilation was monitored with inductance bands. Real-time B-mode ultrasound movies were analysed. We measured genioglossus motion (i) during spontaneous breathing, voluntary targeted breathing (normal tidal volume Vt), and voluntary hyperpnoea (at 1.5Vt and 2 Vt); (ii) during inspiratory flow resistive loading; (iii) with changes in end-expiratory lung volume (EELV).Average peak inspiratory displacement of the infero-posterior region of genioglossus was 0.89±0.56 mm; 1.02±0.88 mm; 1.27±0.70 mm respectively for voluntary Vt, and during voluntary hyperpnoea at 1.5Vt and 2Vt. A change in genioglossus motion was observed with increased Vt. During increasing inspiratory resistive loading, the genioglossus displaced less anteriorly (p = 0.005) but more inferiorly (p = 0.027). When lung volume was altered, no significant changes in genioglossus movement were observed (p = 0.115).In healthy subjects, we observed non-uniform heterogeneous inspiratory motion within the inferoposterior part of genioglossus during spontaneous quiet breathing with mean peak displacement between 0.5-2 mm, with more displacement in the posterior region than the anterior. This regional heterogeneity disappeared during voluntary targeted breathing. This may be due to different neural drive to genioglossus during voluntary breathing. During inspiratory resistive loading, the observed genioglossus motion may serve to maintain upper airway patency by balancing intraluminal negative pressure with positive pressure generated by upper airway dilatory muscles. In contrast, changes in EELV were not accompanied by major changes in genioglossus motion.
Project description:Mandibular advancement surgery may positively affect pharyngeal airways and therefore potentially beneficial to obstructive sleep apnea (OSA).To collect evidence from published systematic reviews that have evaluated pharyngeal airway changes related to mandibular advancement with or without maxillary procedures.PubMed, EMBASE, Web of Science, and Cochrane Library were searched without limiting language or timeline. Eligible systematic reviews evaluating changes in pharyngeal airway dimensions and respiratory parameters after mandibular advancement with or without maxillary surgery were identified and included.This overview has included eleven systematic reviews. Maxillomandibular advancement (MMA) increases linear, cross-sectional plane and volumetric measurements of pharyngeal airways significantly (p<0.0001), while reducing the apnea-hypopnea index (AHI) and the respiratory disturbance index (RDI) significantly (p<0.0001). Two systematic reviews included primary studies that have evaluated single-jaw mandibular advancement, but did not discuss their effect onto pharyngeal airways. Based on the included primary studies of those systematic reviews, single-jaw mandibular advancement was reported to significantly increase pharyngeal airway dimensions (p<0.05); however, conclusive long-term results were lacking.MMA increases pharyngeal airway dimensions and is beneficial to patients suffering from OSA. However, more evidence is still needed to draw definite conclusion related to the effect of single-jaw mandibular advancement osteotomies on pharyngeal airways.
Project description:To measure real-time movement of the tongue and lateral upper airway tissues in obstructive sleep apnea (OSA) subjects during wakefulness using tagged magnetic resonance imaging.Comparison of the dynamic imaging of three groups of increasing severity OSA and a control group approximately matched for age and body mass index (BMI).Not-for-profit research institute.24 subjects (apnea hypopnea index [AHI] range 2-84 events/h, 6 with AHI < 5 events/h).The upper airway was imaged awake in two planes using SPAtial Modulation of Magnetization (SPAMM). Tissue displacements were quantified with harmonic phase analysis.All subjects had dynamic airway opening in the sagittal plane associated with inspiration. In the nasopharynx, the increase in airway cross-sectional area during inspiration correlated with minimal cross-sectional area of the airway (R = 0.900, P < 0.001). AHI correlated negatively with movement of the nasopharyngeal lateral walls (R = - 0.542, P = 0.006). Four movement patterns were observed during inspiration: "en bloc" anterior movement of the whole posterior tongue; movement of only the oropharyngeal posterior tongue; bidirectional movement; or minimal movement. Some subjects showed different inspiratory movement patterns with different breaths. A low AHI (< 5) was associated with en bloc movement (P = 0.002).Inspiratory movement of the tongue varied between and within subjects, likely as a result of local and neural factors. However, in severe OSA inspiratory movement was minimal.Brown EC; Cheng S; McKenzie DK; Butler JE; Gandevia SC; Bilston LE. Respiratory movement of upper airway tissue in obstructive sleep apnea. SLEEP 2013;36(7):1069-1076.
Project description:Obstructive sleep apnea is associated with high blood pressure. The magnitude of blood pressure effects from sleep apnea treatment is unclear. We aimed to determine the effect of mandibular advancement device therapy on ambulatory nighttime and daytime blood pressure in women and men with daytime sleepiness and snoring or mild to moderate sleep apnea (apnea-hypopnea index, <30).In this 4-month, double-blind, randomized controlled trial comprising 96 untreated patients, 27 women and 58 men, aged 31 to 70 years, completed the study. The active group received individually made adjustable mandibular advancement devices, and the control group was given individually made sham devices, to be used during sleep. Polysomnographic sleep recordings and ambulatory 24-hour blood pressure measurements were performed at baseline and at follow-up. In women with mandibular advancement devices, the mean nighttime systolic blood pressure was 10.8 mm Hg (95% confidence interval, 4.0-17.7 mm Hg; P=0.004) lower than in the women in the sham group, adjusted for baseline blood pressure, age, body mass index, and the apnea-hypopnea index. The mean nighttime adjusted diastolic blood pressure was 6.6 mm Hg (95% confidence interval, 2.7-10.4 mm Hg; P=0.002) lower in the mandibular advancement device group. In men, there were no significant differences in blood pressure at night or during the daytime between the intervention groups.A mandibular advancement device for obstructive sleep apnea reduces nocturnal blood pressure in women.URL: https://www.clinicaltrials.gov. Unique identifier: NCT00477009.
Project description:Although continuous positive airway pressure, oral appliances and surgical modifications of the airway are considered as part of the routine management of patients with obstructive sleep apnea, many new and unconventional therapies exist. Many of the trials using these new alternatives have been limited by insufficient data, poor trial design, small sample size, unclear inclusion criteria, lack of randomization, and lack of blinding, and on occasion are biased by retrospective design. Bariatric surgery, positional therapy, auto-titrating positive airway pressure, serotonin agents, wake promoting agents, genioglossus stimulation surgery, supplemental oxygen, nasal dilators, nasal expiratory resistor devices and oropharyngeal exercises will be reviewed. As obstructive sleep apnea impacts the individual and society at large, further research is needed to explore new therapeutic treatment options for obstructive sleep apnea. Therapeutic trials for obstructive sleep apnea must be of rigorous design to prove clinical effectiveness while taking into account both patient satisfaction and cost effectiveness.
Project description:Controversy persists regarding the presence and importance of hypoglossal nerve dysfunction in obstructive sleep apnea (OSA).We assessed quantitative parameters related to motor unit potential (MUP) morphology derived from electromyographic (EMG) signals in patients with OSA versus control subjects and hypothesized that signs of neurogenic remodeling would be present in the patients with OSA.Participants underwent diagnostic sleep studies to obtain apnea-hypopnea indices. Muscle activity was detected with 50-mm concentric needle electrodes. The concentric needle was positioned at more than 10 independent sites per subject, after the local anatomy of the upper airway musculature was examined by ultrasonography. All activity was quantified with subjects awake, during supine eupneic breathing while wearing a nasal mask connected to a pneumotachograph. Genioglossus EMG signals were analyzed offline by automated software (DQEMG), which extracted motor unit potential trains (MUPTs) contributed by individual motor units from the composite EMG signals. Quantitative measurements of MUP templates, including duration, peak-to-peak amplitude, area, area-to-amplitude ratio, and size index, were compared between the untreated patients with OSA and healthy control subjects.A total of 1,655 MUPTs from patients with OSA (n = 17; AHI, 55 ± 6/h) and control subjects (n = 14; AHI, 4 ± 1/h) were extracted from the genioglossus muscle EMG signals. MUP peak-to-peak amplitudes in the patients with OSA were not different compared with the control subjects (397.5 ± 9.0 vs. 382.5 ± 10.0 ?V). However, the MUPs of the patients with OSA were longer in duration (11.5 ± 0.1 vs. 10.3 ± 0.1 ms; P < 0.001) and had a larger size index (4.09 ± 0.02 vs. 3.92 ± 0.02; P < 0.001) compared with control subjects.These results confirm and quantify the extent and existence of structural neural remodeling in OSA.
Project description:Obstructive sleep apnea (OSA) resolves in lateral sleep in 20% of patients. However, the effect of lateral positioning on factors contributing to OSA has not been studied. We aimed to measure the effect of lateral positioning on the key pathophysiological contributors to OSA including lung volume, passive airway anatomy/collapsibility, the ability of the airway to stiffen and dilate, ventilatory control instability (loop gain), and arousal threshold.Non-randomized single arm observational study.Sleep laboratory.20 (15M, 5F) continuous positive airway pressure (CPAP)-treated severe OSA patients.Supine vs. lateral position.CPAP dial-downs performed during sleep to measure: (i) Veupnea: asleep ventilatory requirement, (ii) passive V0: ventilation off CPAP when airway dilator muscles are quiescent, (iii) Varousal: ventilation at which respiratory arousals occur, (iv) active V0: ventilation off CPAP when airway dilator muscles are activated during sleep, (v) loop gain: the ratio of the ventilatory drive response to a disturbance in ventilation, (vi) arousal threshold: level of ventilatory drive which leads to arousal, (vii) upper airway gain (UAG): ability of airway muscles to restore ventilation in response to increases in ventilatory drive, and (viii) pharyngeal critical closing pressure (Pcrit). Awake functional residual capacity (FRC) was also recorded.Lateral positioning significantly increased passive V0 (0.33 ± 0.76L/min vs. 3.56 ± 2.94L/min, P < 0.001), active V0 (1.10 ± 1.97L/min vs. 4.71 ± 3.08L/min, P < 0.001), and FRC (1.31 ± 0.56 L vs. 1.42 ± 0.62 L, P = 0.046), and significantly decreased Pcrit (2.02 ± 2.55 cm H2O vs. -1.92 ± 3.87 cm H2O, P < 0.001). Loop gain, arousal threshold, Varousal, and UAG were not significantly altered.Lateral positioning significantly improves passive airway anatomy/collapsibility (passive V0, pharyngeal critical closing pressure), the ability of the airway to stiffen and dilate (active V0), and the awake functional residual capacity without improving loop gain or arousal threshold.