Tongue Morphology and Posterior Airway Space as Predictors of Response in Patientswith Hypoglossal Nerve Stimulation Therapy

Study Overview
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Brief Summary
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Hypoglossal nerve stimulation (HNS) plays an increasingly important role in managing patients with obstructive sleep apnea (OSA) who do not tolerate CPAP therapy and are not eligible for other alternative treatment options, such as mandibular advancement devices or positional therapy. The posterior upper airway space dimensions are crucial in managing patients with HNS in the patient selection process and therapy control. The lateral collapse of the upper airway is of crucial importance. Lateral collapse at the palatal level and of the oropharyngeal walls is a well-established negative predictive factor for therapeutic success. Patients with complete concentric collapse at the palatal level (pCCC) in drug-induced sedation endoscopy (DISE) must be excluded from the implantation of HNS, which is cumbersome and invasive. Endoscopy has the inherent limitation that only one level can be observed at a given time, and assessment is possibly hampered by phlegm. During activation and titration of HNS, tongue protrusion is observed in the awake patient. However, this method does not allow for assessing the opening of the retroglossal (RG) and retropalatal (RP) airway space, which is the ultimate therapeutic goal. Insufficient opening of the airway is the reason for non-responders with HNS. Insufficient upper airway opening can be either at the retropalatal or retroglossal level. The study aims to identify insufficient airway openings better using sub-mental ultrasonography. Sub-mental standardized and orientated ultrasonography offers a quantitative, reproducible way of assessing transverse upper airway dimensions and anatomic features of the upper airway in a rapid and non-invasive manner. In addition, anatomic characteristics of the airway's adjacent tissue, such as the size and shape of the tongue, may also have an impact on the effectiveness of HNS. Tongue morphology and posterior airway space assessment could be used in preoperative evaluation and during therapeutic titration of HNS. The clinical routine could be included tongue morphology and posterior airway space assessment without additional patient risks. However, the clinical value of assessing posterior airway space and tongue morphology in patients with HNS is yet unknown.

Official Title
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Tongue Morphology and Posterior Airway Space as Predictors of Response in Patientswith Hypoglossal Nerve Stimulation Therapy

Conditions
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Obstructive Sleep Apnea, Sleep-Disordered Breathing

Intervention / Treatment
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* Diagnostic Test: Ultrasonography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients older than 18 year patients with a hypoglossal nerve implantation control group: 15 subjects without OSA (AHI<10/h) written informed consent sufficient knowledge of German or French to understand informed consent Exclusion Criteria: Patients younger than 18 years unwillingness to give informed consent incapable of performing Müller's maneuver history of head and neck surgery other than HNS, tonsillectomy, and maxillomandibular advancement diagnosis of congestive heart failure or chronic pulmonary disease diagnosis of co-morbid sleep disorders, including central sleep apnea pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Obstructive sleep apnea patients<br>39 obstructive sleep apnea patients with hypoglossal nerve stimulation | Diagnostic Test: Ultrasonography<br>* Assessment of tongue morphology and posterior airway space using ultrasonography (AmCAD-UO, CE mark NB1639)<br>|
| Healthy controls<br>15 healthy control participants | Diagnostic Test: Ultrasonography<br>* Assessment of tongue morphology and posterior airway space using ultrasonography (AmCAD-UO, CE mark NB1639)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prediction of therapeutic success with hypoglossal nerve stimulation | Success is defined as apnea-hypopnea index in the most recent sleep testing ≤ 20/h and 50% reduction from baseline | Most recent sleep testing before examination after HNS implantation, a maximum of 6 months before examination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prediction of AHI reduction, defined as the difference between pre- and postoperative AHI, with HNS based on tongue morphology and posterior airway space. | AHI reduction is defined as apnea-hypopnea index in the most recent sleep compared to the baseline value before HNS implantation | Most recent sleep testing before examination after HNS implantation, a maximum of 6 months before examination | 
| Comparison of pharyngeal dimensions between visual assessment and tongue morphology and posterior airway space | Visual assessment is performed both by DISE and wake transnasal endoscopy. Tongue morphology and posterior airway space is analyzed using ultrasonography | through study completion, from 15.05.2023 to 14.05.2024 | 
| Therapeutical guidance using tongue morphology and posterior airway space to identify the obstructing upper airway segment compared to wake fiberoptic endoscopy during HGS in non-responders. | Changes to therapeutic HNS settings during study visit | through study completion, from 15.05.2023 to 14.05.2024 | 
| Patient comfort rated by the patients for wake transnasal endoscopy and sub-mental ultrasonography | Rated on a visual analog scale (VAS) from 0 to 10 (0 meaning no discomfort; 10 meaning very uncomfortable | through study completion, from 15.05.2023 to 14.05.2024 | 
| Information gain through from tongue morphology and posterior airway space imaging | Rating by the physician if the additional information gained from tongue morphology and posterior airway space imaging at functional stimulation threshold is a valuable adjunct to the oral observation of tongue protrusion rated on a VAS | through study completion, from 15.05.2023 to 14.05.2024 | 
| Comparison of pharyngeal dimensions of healthy and patients with OSA and HNS | Pharyngeal dimensions measured using ultrasonography | through study completion, from 15.05.2023 to 14.05.2024 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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hypoglossal nerve stimulation, ultrasonography