Assessment of tongue mechanical properties using different contraction tasks

Severity of tongue base collapse in various body positions in patients with obstructive sleep apnea: A trajectory analysis

BACKGROUND

Drug-induced sleep endoscopy (DISE) is used for evaluating upper airway anatomy and determining airway obstruction patterns. It is typically performed with the patient in the supine position. Airway collapse severity is influenced by body position and level of consciousness; the resultant dynamic changes may vary across patients. In this study, we evaluated the severity of upper airway collapse through awake endoscopy and DISE and identified factors affecting the pattern of airway collapse severity.

METHODS

This study included 66 patients with obstructive sleep apnea. The patients underwent type 1 polysomnography, tongue strength assessment, awake endoscopy in the sitting and supine positions, and DISE. Group-based trajectory modeling was performed to identify patients with different collapse severity patterns in different body positions and at different levels of consciousness.

RESULTS

Patient with similar severity trajectory were assigned to the same group. Two different severity trajectories (group 1 and group 2) were identified at the tongue base level. Tongue depression strength varied significantly between groups 1 and 2 (47.00 vs. 35.00 kPa; P = .047). During awake endoscopy, collapse severity was significantly higher in group 2 than in group 1. Group 1 had lower rapid eye movement/nonrapid eye movement apnea-hypopnea index ratios and higher tongue depression strength than did group 2.

CONCLUSION

In patients with obstructive sleep apnea, tongue strength may vary depending on body position. Our results should be interpreted with caution because of the limited sample size. Future studies should investigate the effect of oropharyngeal rehabilitation on tongue strength and collapse severity.

A review of upper airway physiology relevant to the delivery and deposition of inhalation aerosols

Developing effective oral inhaled drug delivery treatment strategies for respiratory diseases necessitates a thorough knowledge of the respiratory system physiology, such as the differences in the airway channel's structure and geometry in health and diseases, their surface properties, and mechanisms that maintain their patency. While respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma and their implications on the lower airways have been the core focus of most of the current research, the role of the upper airway in these diseases is less known, especially in the context of inhaled drug delivery. This is despite the fact that the upper airway is the passageway for inhaled drugs to be delivered to the lower airways, and their replicas are indispensable in current standards, such as the cascade impactor experiments for testing inhaled drug delivery technology. This review provides an overview of upper airway collapsibility and their mechanical properties, the effects of age and gender on upper airway geometry, and surface properties. The review also discusses how COPD and asthma affect the upper airway and the typical inhalation flow characteristics exhibited by the patients with these diseases.

Oropharyngeal Rehabilitation for Patients With Moderate to Severe Obstructive Sleep Apnea After Transoral Robotic Surgery

OBJECTIVE

To determine whether combined transoral robotic surgery and postoperative oropharyngeal rehabilitation are effective for reducing the severity of obstructive sleep apnea.

STUDY DESIGN

A quasi-experimental study enrolled participants without blinding between May 2019 and April 2021.

SETTING

Single-center study at National Cheng Kung University Hospital.

METHODS

Patients with moderate to severe obstructive sleep apnea who were otherwise healthy were recruited from the ear, nose, and throat department at National Cheng Kung University Hospital. The group undergoing transoral robotic surgery with oropharyngeal rehabilitation (n = 18) received a 12-week intervention consisting of home-based rehabilitation exercises following surgery; the transoral robotic surgery group (n = 17) received surgery only; and the control group (n = 15) received conservative treatment, such as continuous positive airway pressure therapy or other oral appliance therapy. Polysomnography data and tongue muscle performance were measured before and after the interventions.

RESULTS

The group that underwent transoral robotic surgery with oropharyngeal rehabilitation exhibited significantly improved tongue protrusion strength as compared with the transoral robotic surgery-only group, as well as significantly improved apnea-hypopnea index in the supine position vs the control group.

CONCLUSION

In this study, we demonstrated the synergistic effects of transoral robotic surgery and postoperative oropharyngeal rehabilitation for adult patients with obstructive sleep apnea. Objective records should be used to monitor home-based rehabilitation exercises and examine the lasting synergistic effects.

The Different Effect of Tongue Motor Task Training (TTT) and Strength Training (ST) on the Modulation of Genioglossus Corticomotor Excitability and upper airway stability in Rats

STUDY OBJECTIVES

the mechanical efficiency of upper airway (UA) muscles are pivotal in maintaining UA stability. We aimed to investigate if different tongue training approaches could differently induce signs of neuroplastic in the corticomotor pathways and upper airway stability changes.

METHODS

36 Sprague-Dawley rats were trained daily for eight weeks to lick an isotonic force-sensing disc at targeting forces using 30-50% of maximal achieved lick force (MALF) for tongue task training (TTT) or targeting force set above 50%, 60% and 70% of MALF progressively for tongue strength training (TST). Corticomotor excitability was dynamically assessed by GG response to transcortical magnetic stimulation (TMS) at different sessions. GG EMG activity, GG ultrastructure and myosin heavy chain (MHC), UA dynamics were assessed after eight weeks.

RESULTS

After 4 weeks, GG TMS latencies decreased in both tongue training groups when compared with the control group (p<0.05) and this excitability was more stable in TTT group. After 8 weeks, both GG TMS response and EMG activity revealed increased excitability in TTT and TST groups. The apoptotic pathological morphology changes of GG ultrastructure were observed in TST group, but not TTT. Percentage of GG MHC type I fibers in TST group was higher than the control and TTT groups (p<0.05). The UA Pcrit decreased significantly in TTT group (p<0.05) and tend to decrease in TST group (p=0.09).

CONCLUSION

TTT could improve the UA stability and induce the neuroplastic changes more efficiently without training-induced muscle injury, while TST revealed a fatigue-resistance change in GG.

Differences in Predicted Therapeutic Outcome of Mandibular Advancement Determined by Remotely Controlled Mandibular Positioner in Canadian and Chinese Apneic Patients

BACKGROUND

In-lab mandibular protrusive titration using a remotely controlled mandibular positioner (RCMP) could predict the success rate of mandibular advancement device (MAD) and reliably determine the Optimal Protrusive Position (OPP) for obstructive sleep apnea (OSA) patients. The aim of this study was to compare MAD success rate using in-lab RCMP manual titration performed in Caucasian and Chinese OSA patients.

METHODS

Manual RCMP titration was performed during an in-lab sleep study using the same procedure that had been previously reported in untreated Caucasian and Chinese OSA patients. Success rate was determined according to classical success criteria or to those previously used for RCMP titration.

RESULTS

A total of 160 subjects were included in this study, and conclusive data were obtained from 141 (71 Chinese and 70 Caucasian OSA patients). Chinese patients were significantly younger, with lower BMI and more severe OSA disease than the Canadian counterparts. Among patients with predicted success, the OPP expressed in % of full protrusion position did not differ between the two ethnic groups. Chinese ethnicity, younger age and lower baseline AHI were significant determinants of RCMP success. In a multivariate analysis, only ethnicity and AHI were found to significantly account for success, the odds ratio for success in Chinese compared to Caucasians corrected for AHI being 3.7 and 4.6 depending on criteria used to define success.

CONCLUSION

Although the OSA disease was more severe in Chinese patients, the predicted success rate of MAD according to RCMP titration was higher in Chinese than in Caucasians. This study was registered on ClinicalTrials.gov (NCT03231254).

Maximum isometric tongue force in patients with obstructive sleep apnoea

Background

Obstructive sleep apnea (OSA) is a sleep disorder with a prevalence of 9–38%. The underlying pathology in OSA is a collapse of the upper airway. Especially in more severely affected patients, this collapse is often located at the level of the tongue base. Therefore, various implantable systems (anchors and ligament techniques) were developed to prevent or overcome this collapse. These systems are exposed to various forces. Different models have been developed to measure these forces and data comparing forces in healthy individuals with OSA patients are rare.

Purpose

Purpose of the study was to evaluate possible differences in tongue forces between healthy individuals and patients with OSA.

Method

To evaluate maximum isometric tongue forces, we conducted a matched pair design study including 20 healthy individuals and 20 patients suffering from OSA. Maximum isometric tongue forces were measured in an anterior/posterior direction with the help of self-designed new device that clamps the tongue.

Results

We could show that the maximum isometric force does not differ significantly in healthy individuals (10.7 ± 5.2N) from patients with OSA (14.4 ± 6.3N).

Conclusion

Currently there are no indications that maximum isometric tongue force does differ in healthy individuals and patients with OSA. Higher, as well as lower, tongue forces in patients with OSA seem not to differ from healthy subjects and therefore may not be needed to consider, in the development of tongue management devices, for OSA patients.

Hypoglossal nerve stimulation therapy does not alter tongue protrusion strength and fatigability in obstructive sleep apnea

STUDY OBJECTIVES

Hypoglossal nerve stimulation (HNS) is an effective surgical alternative for patients with obstructive sleep apnea (OSA). HNS therapy relies on the stimulation of the hypoglossal nerve to open the upper airways. This stimulation could lead to alterations in tongue strength and fatigability, which could alter treatment outcome over time. The aim of the study was to investigate whether HNS alters tongue strength and fatigability.

METHODS

Tongue protrusion strength (peak pressure in kPa) and fatigability (time to task failure during 50% of peak pressure contraction) were measured with a pressure transducer at least 2 months after HNS implantation (n = 30). These results were compared to a group of patients with OSA (n = 38) and a non-OSA control group (n = 35).

RESULTS

Median tongue protrusion strength was lower (54.7 [43.8, 63.0] versus 60.7 [53.7, 66.0] kPa, P = .013) and fatigue occurred more quickly (21.3 [17.4, 26.3] versus 26.0 [19.3, 31.3] seconds, P = .017) in the patients with OSA compared to the non-OSA control group. In multiple regression analysis, age was a significant factor for tongue strength and diagnosis of OSA for tongue fatigability. Tongue strength and fatigability did not differ between patients with OSA with conservative therapy or observation versus after HNS implantation (51.8 [41.3, 63.4] versus 56.3 [45.0, 62.3] kPa, P = .502; 20.8 [16.3, 26.2] versus 21.8 [18.3, 26.8] seconds, P = .418).

CONCLUSIONS

Tongue strength decreases with age. Tongue fatigability is more pronounced in people with OSA. However, approximately 1.5 years of HNS therapy on average does not alter tongue strength or fatigability compared to an OSA control group.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Change in Tongue Strength and Fatigue After Upper Airway Stimulation Therapy; Identifier: NCT03980158.

Transient upregulation of TASK-1 expression in the hypoglossal nucleus during chronic intermittent hypoxia is reduced by serotonin 2A receptor antagonist

Hypoglossal motoneurons innervate genioglossus muscle, the contraction of which is critical in the maintenance of upper airway patency in patients with obstructive sleep apnea. As a potassium channel distributed in hypoglossal motoneurons, TWIK-related acid-sensitive K+ channel-1 (TASK-1) could be inhibited by 5-HT. This study aimed to investigate if TASK-1 expression in hypoglossal nucleus could be influenced by chronic intermittent hypoxia (CIH) and 5-HT_2A receptors antagonist. Two hundred twenty-eight rats were exposed to CIH or normoxia (NO) in the presence and absence of 5-HT _2A receptor antagonist (MDL-100907) microinjected into the hypoglossal nucleus. The expression of 5-HT and TASK-1 in the hypoglossal nucleus were detected by immunohistochemistry and reverse transcription quantitative polymerase chain reaction on the 1st, 3rd, 7th, 14th and 21st day of CIH exposure. The mean optical density (MOD) of 5-HT in the XII nucleus was significantly increased in the CIH and CIH + MDL group than the NO group on the 7th and 21st day ( p < 0.05). Compared with the NO group, the MOD and gene expression of TASK-1 in the CIH group was significantly increased on the 7th and 14th day ( p < 0.05), then normalized on the 21st day. The TASK-1 expression in the CIH + MDL group was significantly lower than the CIH + PBS and CIH group on the 7th and 14th day ( p < 0.05). The CIH-induced transiently upregulation of the TASK-1 expression in the hypoglossal nucleus could be reversed by 5-HT _2A receptor antagonist, indicating that the modulation of the TASK-1 expression in response to CIH involves 5-HT and 5-HT _2A receptors, and this CIH effect might be 5-HT _2A receptor-dependent.