Efficacy and mechanism of mandibular advancement devices for persistent sleep apnea after surgery: a prospective study

The correlation between the body shape and otolithic function in patients with obstructive sleep apnea

OBJECTIVE

To identify the typical pattern of changes of vestibular-evoked myogenic potentials (VEMPs) and explore the relationship between VEMPs and the anthropometry factors in patients with obstructive sleep apnea (OSA).

METHODS

Patients diagnosed as OSA after overnight polysomnography (PSG) tests were enrolled as the study group. Healthy volunteers were recruited as the control group. Anthropometry data of the body shape and VEMPs results were collected completely. The correlation analysis was conducted among those parameters.

RESULTS

Forty-nine patients with OSA who were diagnosed in the Therapy Center of Sleep-disordered Breathing in our hospital and sex- and age-matched healthy controls as well. Significant changes in ocular and cervical VEMPs (oVEMP and cVEMP) in the study group were observed, which were reduced response rates, elevated thresholds, decreased amplitudes, and prolonged first wave latencies. In oVEMP, the first wave (n1) latency was significantly correlated with weight, body mass index (BMI), neck circumference, waist circumference, hip circumference, and apnea hypopnea index (AHI). In a tentative application, combined use of BMI and oVEMP n1 latency increased the detection rate during OSA screening prior to PSG.

CONCLUSION

OSA can negatively affect function of otolithic organs and their pathways. The first wave latency of the VEMPs waveform may be another important parameter to define peripheral nervous system lesions caused by systemic diseases as OSA.

Uneven Effects of Sleep Apnea on Semicircular Canals and Otolithic Organs

OBJECTIVE

This study aimed to explore how obstructive sleep apnea (OSA) affects the function of each vestibular organ and to identify the correlations among them.

METHODS

A prospective study was conducted involving 32 healthy controls and 64 patients with OSA. The objective detection methods of the utricle and saccule are vestibular-evoked myogenic potentials (VEMPs). A combination of the caloric test and video head impulse test (vHIT) was used to comprehensively evaluate the objective function of semicircular canals.

RESULTS

Elevated thresholds (p < 0.001), decreased waveform amplitudes (p < 0.001), prolonged first wave latencies (p < 0.001), and shortened first interpeak latencies (p < 0.001) were observed in both ocular VEMP (oVEMP) and cervical VEMP (cVEMP). A significant difference was found in the caloric test comparison (χ² = 4.030, p = 0.045) but not in the vHIT. The intergroup comparison of normal rates among the VEMPs, caloric test, and vHIT groups showed a significant difference (p < 0.001).

CONCLUSION

The impairment of vestibular function in patients with OSA was uneven and biased. More attention should be given to vestibular dysfunction in the diagnosis and treatment of OSA.

Characteristic manifestation of ocular and cervical vestibular evoked myogenic potentials findings in severe obstructive sleep apnea patients

BACKGROUND

Studies of saccular and utricular function in patients with obstructive sleep apnea (OSA) are rare. We noticed that some OSA patients also had positive results in vestibular function tests, and this inspired our interest in exploring the vestibular function patterns of OSA patients.

OBJECTIVES

To investigate otolithic organ function in severe OSA patients who lack vestibular symptoms and systemic disease.

MATERIAL AND METHODS

32 patients (64 ears) with severe OSA and 22 healthy controls (44 ears) were enrolled. The ocular and cervical vestibular-evoked myogenic potentials (oVEMP and cVEMP) and the caloric test were recorded and analyzed.

RESULTS

The response rates of oVEMP (73.4%) and cVEMP (82.8%) in patients with severe OSA were significantly lower than those in controls. In oVEMP, elevated thresholds (p = .002), decreased n1-p1 amplitudes (p < .001), prolonged n1 latencies (p < .001) were observed. In cVEMP, the elevation of thresholds (p < .001), decrease in p1-n1 amplitudes (p < .001), and n1-p2 amplitudes (p < .001), prolongation of p1 latencies (p = .003) were observed. No significant difference in the caloric test was found between the two groups.

CONCLUSIONS AND SIGNIFICANCE

Disappearance or impairment of VEMPs could be observed in patients with severe OSA, and reflects different degrees of impairment in the utricle and saccule.

Tongue Function: An Underrecognized Component in the Treatment of Obstructive Sleep Apnea with Mandibular Repositioning Appliance

Obstructive sleep apnea (OSA) is a common but still underrecognized disorder. A mandibular repositioning appliance (MRA) is used to treat OSA by advancing the mandible and thereby reducing the collapsibility of the upper airway. It has been found that an MRA increases the volume of the upper airway, especially the velopharyngeal area, in OSA patients. We hypothesize that this increase in the velopharyngeal volume is associated with an anterior displacement of the tongue, but likely not with a stretching of the soft tissue connecting the soft palate, lateral pharynx, palatopharyngeal arch, and mandible. Since the function and structure of the genioglossus and hypoglossal nerve are always abnormal in patients with OSA, the tongue does not always move simultaneously with the mandible when an MRA is being used. Oropharyngeal exercises, especially tongue exercises, can improve the quality of life of OSA patients, including reduction of daytime sleepiness and snoring, better quality of sleep, and partial decrease in the AHI. Further, in animal models, tongue exercise is also found to be effective in tongue function recovery and in the remodeling of the hypoglossal nucleus. We suggest that a combination of tongue exercises along with MRA is a promising approach for patients who do not respond to an MRA alone.

The Finite Element Simulation of the Upper Airway of Patients with Moderate and Severe Obstructive Sleep Apnea Hypopnea Syndrome

Objectives

To investigate the snoring modes of patients with Obstructive Sleep Apnea Hypopnea Syndrome and to discover the main sources of snoring in soft tissue vibrations.

Methods

A three-dimensional finite element model was developed with SolidEdge to simulate the human upper airway. The inherent modal simulation was conducted to obtain the frequencies and the corresponding shapes of the soft tissue vibrations. The respiration process was simulated with the fluid-solid interaction method through ANSYS.

Results

The first 6 orders of modal vibration were 12 Hz, 18 Hz, 21 Hz, 22 Hz, 36 Hz, and 39 Hz. Frequencies of modes 1, 2, 4, and 5 were from tongue vibrations. Frequencies of modes 3 and 6 were from soft palate vibrations. Steady pressure distribution and air distribution lines in the upper airway were shown clearly in the fluid-solid interaction simulation results.

Conclusions

We were able to observe the vibrations of soft tissue and the modeled airflow by applying the finite element methods. Future studies could focus on improving the soft tissues vibration compliances by adjusting the model parameters. Additionally, more attention should be paid to vibrational components below 20 Hz when performing an acoustic analysis of human snore sounds due to the presence of these frequencies in this model.