Targeted hypoglossal nerve stimulation for the treatment of obstructive sleep apnea: Six-month results

Exploring hypoglossal nerve stimulation therapy for obstructive sleep apnea: A comprehensive review of clinical and physiological upper airway outcomes

Obstructive sleep apnea (OSA) is a chronic disorder characterized by recurrent episodes of upper airway collapse during sleep, which can lead to serious health issues like cardiovascular disease and neurocognitive impairments. While positive airway pressure serves as the standard treatment, intolerance in some individuals necessitates exploration of alternative therapies. Hypoglossal nerve stimulation (HGNS) promises to mitigate OSA morbidity by stimulating the tongue muscles to maintain airway patency. However, its effectiveness varies, prompting research for optimization. This review summarizes the effects of HGNS on upper airway obstruction from human and animal studies. It examines physiological responses including critical closing pressure, maximal airflow, nasal and upper airway resistance, compliance, stiffness, and geometry. Interactions among these parameters and discrepant findings in animal and human studies are explored. Additionally, the review summarizes the impact of HGNS on established OSA metrics, such as the apnea-hypopnea index, oxygen desaturation index, and sleep arousals. Various therapeutic modalities, including selective unilateral or bilateral HGNS, targeted unilateral HGNS, and whole unilateral or bilateral HGNS, are discussed. This review consolidates our understanding of HGNS mechanisms, fostering exploration of under-investigated outcomes and approaches to drive advancements in HGNS therapy.

Comprehensive Analysis of Adverse Events Associated With Hypoglossal Nerve Stimulators: Insights From the MAUDE Database

OBJECTIVE

This study aims to examine the adverse events associated with hypoglossal nerve stimulator (HNS) implantation for treating obstructive sleep apnea (OSA), drawing data from the Manufacturer and User Facility Device Experience (MAUDE) database. We aim to provide a comprehensive and updated account of these adverse events.

STUDY DESIGN

Retrospective analysis.

SETTING

MAUDE Database review.

METHODS

A retrospective analysis was performed on the MAUDE database to collect all HNS-related reports from May 2014 to December 2023. Variables collected included date of event, event description, nature of event, iatrogenic injuries, required interventions, and, if available, root causes. Each event description was analyzed to classify the adverse event, the postevent intervention, and device model number.

RESULTS

Out of 1178 reports fulfilling the inclusion criteria, 1312 adverse events were identified. Common adverse events included infection (24.0%), pain (19.7%), and hematoma/seroma (10.2%). Approximately 83.1% of these adverse events necessitated medical and/or surgical intervention. The most frequent procedures included explantation (29.4%) and device repositioning (15.8%). Pneumothorax was reported in 50 cases, with 41 (82.0%) requiring a chest tube to be inserted. Three adverse events described overstimulation in the setting of magnetic resonance imaging (MRI) despite the implantation of MRI-compatible second-generation internal pulse generators.

CONCLUSION

While HNS implantation has been established as a reliable intervention for OSA in cases of continuous positive airway pressure failure or intolerance, this study highlights several perioperative and postoperative difficulties and complications. Understanding these challenges is essential for refining surgical practices and enhancing patient consent processes, ultimately aiming to improve therapeutic outcomes.

[Ten years of hypoglossal nerve stimulation in obstructive sleep apnea: a systematic literature review]

OBJECTIVE

To show the importance of hypoglossal nerve stimulation (HGNS) as a treatment method for obstructive sleep apnea (OSA) in the German healthcare context and to better assess the way patients who do not receive adequate care could benefit from HGNS.

METHODS

A systematic literature review in the Medline and Cochrane Library literature database was conducted, including publications using different stimulation technologies for HGNS. The efficacy of HGNS was assessed based on patient-relevant outcomes (daytime sleepiness, quality of life), treatment adherence and the apnea-hypopnea index (AHI) and oxygen desaturation index (ODI). The safety of the treatment method was assessed based on adverse events (AEs).

RESULTS

Inclusion and analysis of 33 publications: 2 randomized controlled trials (RCTs, level Ib), 1 level IIb trial (n = 1) and 30 level IV trials with a study duration of up to 60 months. The RCTs showed better values for daytime sleepiness and quality of life when using HGNS than in the control group. AHI and ODI showed a deterioration under placebo stimulation or therapy withdrawal in the RCTs. Consistently high adherence was also reported in the long-term course. Severe AEs under HGNS were rare and could usually be resolved by repositioning electrodes or replacing device components. Other AEs were mostly transient or could be resolved by non-invasive measures. All investigated parameters showed similar results in the evaluated studies. The results of different stimulation systems are comparable in type and extent.

CONCLUSION

The comprehensive review of the literature shows consistent data that highlight the importance of HGNS as an effective and safe treatment for OSA after unsuccessful CPAP treatment. The evaluation also shows that the different stimulation systems make it possible to better tailor the therapy to the patient's individual requirements. A future systematic evaluation of real-world data on the use of HGNS would help gain additional insights into the relevance of the method in routine clinical practice.

Defining the Shape of the Mylohyoid Muscle: A Morphometric Imaging Study

OBJECTIVES

Implantable hypoglossal nerve stimulation (HNS) therapy is an evolving therapeutic alternative for patients with refractory obstructive sleep apnea (OSA). The muscular anatomy of this region has implications for surgical access through this zone as well as positioning and anchoring of hardware in this area. The purpose of this study was to radiologically describe the topography of the mylohyoid muscle and adjacent structures across a wide age spectrum.

METHODS

We retrospectively evaluated computed tomography scans of the neck in 102 patients who were imaged for reasons unrelated to the floor of mouth or submental space. Patients with prior surgery or pathology in the area of interest were excluded. Fourteen relevant muscle measurements were made on a midline sagittal image and a coronal image positioned at the midpoint between the hyoid bone and the mandible.

RESULTS

We included 49 men and 53 women with an average age of 44 years (range 19-70). The average mylohyoid length was 42 mm; the average distance between the anterior digastric bellies was 17 mm. The average angle of the central mylohyoid was 174° in the sagittal plane and 164° in the coronal plane. Several measurements were significantly correlated with patient age, including the angle measurements and the distance between the digastric muscles. Aberrant digastric anatomy was common.

CONCLUSIONS

The mylohyoid muscle has multiple radiologically distinct segments with predictable curvatures. An understanding of submental muscular anatomy, along with its variability between patients, may be beneficial to the development of bilateral implantable neurostimulation technology for the treatment of refractory OSA.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:2970-2975, 2024.

Case report of hypoglossal nerve stimulation therapy failure due to significant underlying central sleep apnea

Hypoglossal nerve stimulation is indicated for obstructive sleep apnea but is ineffective in treating central sleep apnea. We describe 2 patients implanted with hypoglossal nerve stimulation after being diagnosed with obstructive sleep apnea at outside sleep laboratories and failing a trial of continuous positive airway pressure therapy. Despite successful hypoglossal nerve stimulation implantation, the patients continued to have persistent symptoms with residual apnea-hypopnea indices above 25 events/h. Although obstructive sleep apnea was the presenting diagnosis, we discovered a significant central sleep apnea component in the original diagnostic sleep data upon careful review. One patient was confirmed to have a central sleep apnea-predominant sleep disorder and improved with adaptive servo-ventilation therapy. The other was diagnosed with central sleep apnea and severe periodic limb movement disorder, and improved with medication. Based on these sleep apnea cases, we propose guidelines emphasizing the importance of reviewing basic clinical information upon treatment failure and initiating multidisciplinary collaboration early in the treatment course.

CITATION

Banerjee D, Lee C-H, Im K. Case report of hypoglossal nerve stimulation therapy failure due to significant underlying central sleep apnea. J Clin Sleep Med. 2024;20(6):1003-1007.

Advances in the Use of Hypoglossal Nerve Stimulator in Adolescents With Down Syndrome and Persistent Obstructive Sleep Apnea-A Systematic Review

INTRODUCTION

The Hypoglossal Nerve Stimulator (HNS) is a novel therapy that has been extensively studied in adults and more recently, it has been incorporated in children with Down Syndrome (DS) with persistent obstructive sleep apnea after adenotonsillectomy and trial of continuous positive airway pressure treatment. This systematic review article aims to examine the existing literature on HNS use in children to explore the benefits, efficacy, and parental experiences.

METHODS

MEDLINE, Web of Science and EMBASE were searched to include all studies published up to March 2nd, 2023, on the topic of HNS use in pediatric population under 21 years old.

RESULTS

A total of 179 studies were initially identified from which 10 articles were consistent with the inclusion criteria. Nine articles addressed outcomes after implantation of the HNS device in children with DS and 1 article explored the parental experiences. Findings were similar across studies where after implantation of HNS, there was marked improvement in polysomnographic outcomes and quality of life scores with high level of compliance.

CONCLUSIONS

HNS holds promise as an effective treatment option for pediatric patients with DS and persistent OSA after AT and CPAP trials. It significantly improves sleep-disordered breathing, quality of life, and neurocognitive measures, leading to substantial and sustained benefits for these children. While the findings are encouraging, further research is needed to explore the potential of HNS in other pediatric populations without DS and to raise awareness among healthcare providers about this treatment option. Overall, HNS may offer significant long-term benefits for the overall well-being and health of pediatric patients with DS and persistent OSA.

Hypoglossal nerve stimulation for adults with obstructive sleep apnea

ABSTRACT

Obstructive sleep apnea (OSA) is a common chronic condition in which upper airway collapse interferes with breathing during sleep, reducing sleep quality. Untreated OSA can impair a patient's health and quality of life. The recommended first-line treatment for OSA in adults is positive airway pressure, but difficulty tolerating this device limits adherence to treatment for many patients. Treatment with an implanted hypoglossal nerve stimulation (HNS) device is a relatively new second-line option for these patients, and is gaining more widespread use. Clinicians who treat OSA or provide other healthcare services to patients with HNS implants should be familiar with these devices. This article reviews HNS technology and relevant OSA pathophysiology, along with device candidacy criteria, efficacy, risks, and considerations related to use of other medical technologies for patients with HNS implants.

Increased Body Mass Index Correlates with Less Favorable Postoperative Outcomes After Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea: A Retrospective Cohort Study

OBJECTIVE

Obstructive sleep apnea is associated with high morbidity. Hypoglossal nerve stimulation (HNS) has become a novel (neuro-) surgical treatment strategy for obstructive sleep apnea, demonstrating good success rates. Beyond predefined inclusion and exclusion criteria, no precise data are available, enabling individual preoperative risk assessment. To improve preoperative risk stratification, this study analyzed individual patient factors that affect outcomes of HNS.

METHODS

Fourteen patients treated with unilateral HNS were analyzed retrospectively. Assessed risk factors included: hypertension, diabetes mellitus, depression, smoking, alcohol consumption, body mass index (BMI), and disease duration. Treatment success was defined as a reduction in the postoperative apnea-hypopnea index (AHI) to ≤20 events/hour, with a relative reduction of at least 50% compared to baseline.

RESULTS

A significant reduction in the postoperative apnea-hypopnea index was observed in all patients (P < 0.0001). BMI correlated significantly with postoperative AHI scores (95% confidence interval, 0.1519-0.8974; P = 0.018). Significant treatment success was observed in 50% of patients. Compared with the "Excellent Responder group," the "Responder group" demonstrated a significantly higher BMI (95% confidence interval, 1.174-6.226; P = 0.0078). Diabetes, hypertension, disease duration, smoking, depression, and alcohol consumption were not significantly associated with AHI reduction.

CONCLUSIONS

Our findings suggest that BMI may be an independent risk factor for the response to HNS, with patients who had less benefit from therapy having significantly higher BMI than "Excellent Responders." Therefore, carefully selecting patients is crucial in obtaining optimal outcomes with HNS therapy, especially those with a high BMI.

Patient-reported outcomes with hypoglossal nerve stimulation for treatment of obstructive sleep apnea: a systematic review and meta-analysis

INTRODUCTION

Hypoglossal nerve stimulation (HNS) has recently been introduced as an alternative treatment for patients with OSA. A large number of studies have demonstrated substantial changes in OSA with this therapy by reducing respiratory events and improving symptoms such as daytime sleepiness and quality of life. The objective of this review was to conduct a systematic review and meta-analysis to evaluate patient-reported outcomes and experience with HNS therapy.

METHODS

A systematic literature search of MEDLINE, Cochrane, and Web of Science was performed to identify randomized controlled and observational studies reporting subjective outcomes with different HNS systems in patients with OSA. Abstracts of 406 articles were screened and a subset of 55 articles were reviewed for eligibility. Risk of bias was assessed using the ROBINS-I tool. Meta-analysis using RevMan was performed when > 2 studies were identified that reported data on a specific outcome.

RESULTS

Thirty-four publications reporting data on 3785 patients with a mean follow-up of 11.8 ± 12.2 months were identified and included in the meta-analysis. The analysis revealed a pooled effect of 4.59 points improvement in daytime sleepiness as measured by the ESS questionnaire (Z = 42.82, p < .001), 2.84 points improvement in daytime functioning as measured by the FOSQ score (Z = 28.38, p < .001), and 1.77 points improvement in sleep quality as measured by the PSQI questionnaire (Z = 2.53, p = .010). Patient-reported experience was consistently positive and revealed additional relevant aspects from this perspective.

CONCLUSION

HNS therapy significantly improves quality of life in patients with OSA and reliably produces clinically meaningful effects on daytime sleepiness, daytime functioning, and sleep quality. Treatment regularly meets or exceeds the minimum clinically important differences defined for the respective instruments. Additional research is needed to further investigate effects on quality of life beyond improvements in daytime sleepiness and daytime functioning.

Beyond CPAP: modifying upper airway output for the treatment of OSA

Obstructive Sleep Apnea (OSA) is exceedingly common but often under-treated. Continuous positive airway pressure (CPAP) has long been considered the gold standard of OSA therapy. Limitations to CPAP therapy include adherence and availability. The 2021 global CPAP shortage highlighted the need to tailor patient treatments beyond CPAP alone. Common CPAP alternative approaches include positional therapy, mandibular advancement devices, and upper airway surgery. Upper airway training consists of a variety of therapies, including exercise regimens, external neuromuscular electrical stimulation, and woodwind instruments. More invasive approaches include hypoglossal nerve stimulation devices. This review will focus on the approaches for modifying upper airway muscle behavior as a therapeutic modality in OSA.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Targeted Hypoglossal Nerve Stimulation for Patients With Obstructive Sleep Apnea: A Randomized Clinical Trial

Importance

Evidence is lacking from randomized clinical trials of hypoglossal nerve stimulation in obstructive sleep apnea (OSA).

Objective

To evaluate the safety and effectiveness of targeted hypoglossal nerve stimulation (THN) of the proximal hypoglossal nerve in patients with OSA.

Design, Setting, and Participants

This randomized clinical trial (THN3) was conducted at 20 centers and included 138 patients with moderate to severe OSA with an apnea-hypopnea index (AHI) of 20 to 65 events per hour and body mass index (calculated as weight in kilograms divided by height in meters squared) of 35 or less. The trial was conducted from May 2015 through June 2018. Data were analyzed from January 2022 through January 2023.

Intervention

Implant with THN system; randomized 2:1 to activation at month 1 (treatment) or month 4 (control). All received 11 months of THN with follow-up at months 12 and 15, respectively.

Main Outcomes and Measures

Primary effectiveness end points comprised AHI and oxygen desaturation index (ODI) responder rates (RRs). Treatment responses at months 4 and 12/15 were defined as a 50% or greater reduction in AHI to 20 or less per hour and an ODI decrease of 25% or greater. Coprimary end points comprised (1) month 4 AHI and ODI RR in the treatment greater than the control group and (2) month 12/15 AHI and ODI RR in the entire cohort exceeding 50%. Secondary end points included sleep apnea severity (AHI and ODI) and patient-reported outcomes (Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, and EQ-5D visual analog scale).

Results

Among 138 participants, the mean (SD) age was 56 (9) years, and 19 (13.8%) were women. Month 4 THN RRs were substantially greater in those in the treatment vs control group (AHI, 52.3% vs 19.6%; ODI, 62.5% vs 41.3%, respectively) with treatment-control standardized mean differences of 0.725 (95% CI, 0.360-1.163) and 0.434 (95% CI, 0.070-0.843) for AHI and ODI RRs, respectively. Months 12/15 RRs were 42.5% and 60.4% for AHI and ODI, respectively. Improvements in AHI, ODI, Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, and EQ-5D visual analog scale scores were all clinically meaningful (medium to large effect size). Two serious adverse events and 100 nonserious related adverse events were observed from the implant procedure or study protocol.

Conclusions and Relevance

This randomized clinical trial found that THN demonstrated improvements in sleep apnea, sleepiness, and quality of life in patients with OSAs over an extended AHI and body mass index range without prior knowledge of pharyngeal collapse pattern. Clinically meaningful improvements in AHI and patient-reported responses compared favorably with those of distal hypoglossal nerve stimulation trials, although clinically meaningful differences were not definitive for ODI.

Trial Registration

ClinicalTrials.gov Identifier: NCT02263859.

Hypoglossal nerve trunk stimulation: electromyography findings during drug-induced sleep endoscopy: a case report

BACKGROUND

Literature has demonstrated hypoglossal nerve stimulation to be a safe and effective treatment for patients with obstructive sleep apnea nonadherent to positive airway pressure therapy. However, the recommended criteria for patient selection are still unable to identify all the unresponsive patients, highlighting the need for improved understanding about hypoglossal nerve stimulation for obstructive sleep apnea.

CASE PRESENTATION

A 48-year-old Caucasian male patient with obstructive sleep apnea had been successfully treated with electrical stimulation of the hypoglossal nerve trunk, documented by level 1 polysomnography data. However, due to snoring complaints, he underwent postoperation drug-induced sleep endoscopy for evaluation of electrode activation during upper airway collapse, aiming to improve electrostimulation parameters. Concurrent surface electromyography of the suprahyoid muscles and masseter was obtained. Activation of electrodes 2, 3, and 6 promoted upper airway opening most strongly at the velopharynx and tongue base during drug-induced sleep endoscopy. The same channels also significantly increased the electrical activity on suprahyoid muscles bilaterally, but predominantly on the stimulated side (right). The masseters also presented a considerable asymmetry in electrical potential on the right side (> 55%).

CONCLUSION

Beyond the genioglossus muscle, our findings demonstrate recruitment of other muscles during hypoglossal nerve stimulation, which may be attributed to the electrical stimulation of the nerve trunk. This data provides new insights on how stimulation of the hypoglossal nerve trunk may contribute to obstructive sleep apnea treatment.

Changes in tongue morphology predict responses in pharyngeal patency to selective hypoglossal nerve stimulation

STUDY OBJECTIVES

The major goal of the study was to determine whether changes in tongue morphology under selective hypoglossal nerve therapy for obstructive sleep apnea were associated with alterations in airway patency during sleep when specific portions of the hypoglossal nerve were stimulated.

METHODS

This case series was conducted at the Johns Hopkins Sleep Disorders Center at Johns Hopkins Bayview Medical Center. Twelve patients with apnea implanted with a multichannel targeted hypoglossal nerve-stimulating system underwent midsagittal ultrasound tongue imaging during wakefulness. Changes in tongue shape were characterized by measuring the vertical height and polar dimensions between tongue surface and genioglossi origin in the mandible. Changes in patency were characterized by comparing airflow responses between stimulated and adjacent unstimulated breaths during non-rapid eye movement sleep.

RESULTS

Two distinct morphologic responses were observed. Anterior tongue base and hyoid-bone movement (5.4 [0.4] to 4.1 [1.0] cm (median and [interquartile range]) with concomitant increases in tongue height (5.0 [0.9] to 5.6 [0.7] cm) were associated with decreases in airflow during stimulation. In contrast, comparable anterior hyoid movement (tongue protrusion from 5.8 [0.5] to 4.5 [0.9] cm) without significant increases in height (5.2 [1.6] to 4.6 [0.8] cm) were associated with marked increases in airflow during sleep.

CONCLUSIONS

Tongue protrusion with preservation of tongue shape predicted increases in patency, whereas anterior movement with concomitant increases in height were associated with decreased pharyngeal patency. These findings suggest that pharyngeal patency can be best stabilized by stimulating lingual muscles that maintain tongue shape while protruding the tongue, thereby preventing it from prolapsing posteriorly during sleep.

CITATION

Fleury Curado T, Pham L, Otvos T, et al. Changes in tongue morphology predict responses in pharyngeal patency to selective hypoglossal nerve stimulation. J Clin Sleep Med. 2023;19(5):947-955.

Design and rationale for the treating Obstructive Sleep Apnea using Targeted Hypoglossal Nerve Stimulation (OSPREY) trial

Obstructive sleep apnea (OSA) affects nearly 1 billion people worldwide, including approximately 35 million US residents. OSA has detrimental cardiovascular and neurocognitive consequences. Positive airway pressure corrects sleep disordered breathing but is not always tolerated or used sufficiently. Oral appliances and surgery provide alternatives in select populations but are variably effective. Hypoglossal nerve stimulation can effectively treat obstructive sleep apnea. Targeted hypoglossal nerve stimulation (THN) is simpler than incumbent technology with no sensor and an easier, proximal electrode implantation. The third clinical study of THN, THN3, was the first randomized, controlled trial of hypoglossal nerve stimulation to demonstrate significant improvement of sleep disordered breathing in OSA. The present investigation reports the design of a novel trial of targeted stimulation to provide additional Level 1 evidence in moderate to severe obstructive apnea. OSPREY is a randomized, parallel-arm, 13-month trial wherein all subjects are implanted, 2/3 are activated at Month 1 ("Treatment") and 1/3 are activated at Month 7 ("Control"). The primary endpoint is the difference in apnea-hypopnea index response rates between Treatment and Control groups at Month 7. Secondary endpoints include quality of life and oximetry metrics. OSPREY follows an adaptive "Goldilocks" design which optimizes the number of subjects with the need for high-confidence results. A maximum of 150 subjects is allowed, at which study power of >95% is predicted. Interim analyses begin once 50 patients are randomized and recur after each 20 additional randomizations to detect early success or futility. OSPREY is a unique, efficient trial that should provide high-confidence confirmation of the safety and efficacy of targeted hypoglossal nerve stimulation for moderate to severe obstructive sleep apnea.

Patient Related Outcome and Therapy Effects in Stimulation Treatment of Sleep-Related Breathing Disorders

Several neurostimulation devices exist for the treatment of various sleep-related breathing diseases. The most data for hypoglossal nerve stimulation (HNS) in the therapy of obstructive sleep apnea (OSA) derive the HNS with respiratory sensing. Herewith, daytime sleepiness measured with the Epworth Sleepiness Scale (ESS) was improved in several publications by 5 points with a stability shown for up to several years. Sleep related quality of life, documented with the Functional Outcomes of Sleep Questionnaire, increased by 2 points. In many cohorts showed a mean usage of 5 to 6 hours per night. Under the consideration of shorter follow-ups and smaller group sizes, the ESS improved by 4 under unilateral continuous HNS and by 3 under bilateral HNS. Transvenous stimulation of the phrenic nerve is approved for the treatment in central sleep apnea. In a pivotal trial with 5 year follow-up data, an ESS reduction is documented by 3 points. There is one publication describing a usage of more than 5 hours. The daytime enoral neuromuscular electrical therapy improved ESS (2 points) and sleep-related quality of life of the snoring patients and the bed partner. The daytime training for the effects during the night adherence is given with 83%. For all described devices, there are running or announced studies and/or registry trials that consider patient related outcome.

Hypoglossal Nerve Stimulation Therapy

Hypoglossal nerve stimulation (HNS) has been shown to be a safe alternative in the treatment of moderate-to-severe obstructive sleep apnea (OSA). A recent meta-analysis of 12 studies by Costantino et al. indicated the surgical success rates at 55-75%, a reduction of the apnea hypopnea index (AHI) of 18 events/h, and a reduction of the Epworth Sleepiness Scale (ESS) of 2.9-5.3. After animal studies in the 1970s, the first trial on humans to decrease upper airway resistance by transcutaneous electrical stimulation of the genioglossus was reported in 1989. A separate stimulation of protruding and retracting muscles was realized in 1995 by fine-wire electrodes that were placed into the tongue transoral. Over the next years, several companies developed implantable devices for hypoglossal stimulation in OSA. Initially, devices were developed that used unilateral stimulation of the hypoglossal nerve. In 2014, a device for unilateral respiratory frequency-controlled hypoglossal stimulation finally received FDA approval after a successful phase III trial. In recent years, a device for bilateral breath rate-independent stimulation of the hypoglossal nerve has been added to these approaches as a new development. Accordingly, hypoglossal nerve stimulation, on the one hand, is now an established tool for patients with OSA when standard treatments are not satisfactory. Beyond that, hypoglossal stimulation is undergoing a continuous and impressive development like hardly any other field of surgical therapy for OSA.

Hypoglossal nerve stimulation for obstructive sleep apnea: updated position paper of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

Since the first statement of the German Society of Oto-Rhino-Laryngology, hypoglossal nerve stimulation (HNS) is meanwhile an established treatment option for obstructive sleep apnea (OSA). There are three HNS systems available in Germany which differ in their technical details of the underlying comparable basic principle. For the unilateral HNS with respiratory sensing, several comparative studies, high-volume register analysis and long-term reports exist. The continuous HNS without respiratory sensing does not require a sleep endoscopy for indication. For the bilateral continuous HNS as the single partially implantable device, a feasibility study exists. For indication, the assessment of positive airway pressure failure by sleep medicine is crucial, and the decision for HNS should be made in discussion of other treatment options for at least moderate OSA. The implantation center holds primarily responsibility among the interdisciplinary sleep team and is primary contact for the patient in problems. This depicts why structural processes are required to secure outcome quality and minimize the complications. The aftercare of HNS patients can be provided interdisciplinary and by different medical institutions, whereat, minimal reporting standards to document outcome and usage are recommended.

[Hypoglossal Nerve Stimulation in the Treatment of Obstructive Sleep Apnea]

Reduced genioglossus muscle tone is considered one of the major causes for obstructive sleep apnea (OSA). Hypoglossal nerve stimulation (HNS) keeps the upper airway patent by increasing the muscle tone of the genioglossus muscle being the major airway opener. According to the German S3-Guideline on Sleep Disordered Breathing this treatment is indicated in patients with OSA failing or rejecting positive airway pressure, showing an AHI between 15 and 65, in particular when anatomy is normal and the BMI below 35. In 2021 it has been made available for regular patient care in Germany. However, breathing synchronized, continuous, and bilateral HNS differ in parts relevantly regarding their patient selection criteria, technical features, surgical technique, therapy setting and programming, and daily use for the patient. There are many publications showing the safety, efficacy, and patient satisfaction of breathing synchronized HNS. Less but promising data are available for continuous and the most recent bilateral HNS.

Referral of adults with obstructive sleep apnea for surgical consultation: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment

INTRODUCTION

This systematic review provides supporting evidence for the accompanying clinical practice guideline on the referral of adults with obstructive sleep apnea (OSA) for surgical consultation.

METHODS

The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies that compared the use of upper airway sleep apnea surgery or bariatric surgery to no treatment as well as studies that reported on patient-important and physiologic outcomes pre- and postoperatively. Statistical analyses were performed to determine the clinical significance of using surgery to treat obstructive sleep apnea in adults. Finally, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations.

RESULTS

The literature search resulted in 274 studies that provided data suitable for statistical analyses. The analyses demonstrated that surgery as a rescue therapy results in a clinically significant reduction in excessive sleepiness, snoring, blood pressure (BP), apnea-hypopnea index (AHI), respiratory disturbance index (RDI), oxygen desaturation index (ODI), increase in lowest oxygen saturation (LSAT), sleep quality, and improvement in quality of life in adults with OSA who are intolerant or unaccepting of positive airway pressure (PAP) therapy. The analyses demonstrated that surgery as an adjunctive therapy results in a clinically significant reduction in optimal PAP pressure and improvement in PAP adherence in adults with OSA who are intolerant or unaccepting of PAP due to side effects associated with high pressure requirements. The analyses also demonstrated that surgery as an initial treatment results in a clinically significant reduction in AHI/RDI, sleepiness, snoring, BP, and ODI, and increase in LSAT in adults with OSA and major anatomical obstruction. Analysis of bariatric surgery data showed a clinically significant reduction in BP, AHI/RDI, sleepiness, snoring, optimal PAP level, BMI, ODI, and an increase in LSAT in adults with OSA and obesity. Analyses of very limited evidence suggest that upper airway surgery does not result in a clinically significant increase in risk of serious persistent adverse events and suggested that bariatric surgery may result in a clinically significant risk of iron malabsorption that may be managed with iron supplements. The task force provided a detailed summary of the evidence along with the quality of evidence, the balance of benefits and harms, patient values and preferences, and resource use considerations.

Noninvasive electrical stimulation of oropharyngeal muscles in obstructive sleep apnea

Introduction: Continuous positive airway pressure (CPAP) therapy remains the standard treatment for obstructive sleep apnea. However, its proven effect is useless if the patient does not tolerate the treatment. The electrical stimulation approach has been investigated for several decades now and it seems that the implantable devices for invasive electrical stimulation of hypoglossal nerve are viewed as effective with some of them already approved for human use.Areas covered: in this review, we intent to summarize the existing records of noninvasive stimulation in sleep apnea to make the scientific community aware of the details before deciding on its future. We believe that this is a battle still to fight and more could be done bearing in mind the safety of this method.Expertopinion: noninvasive electrical stimulation has been left behind based on few, small and inconsistent studies using different stimulation parameters. These studies are difficult to compare and to draw conclusions.Electrical stimulation is a field for research in the treatment of obstructive sleep apnea, with many aspects still to be discovered, and which may become a therapeutic alternative to the use of CPAP in certain patients.

Obstructive Sleep Apnea: Non-positive Airway Pressure Treatments

Undiagnosed and untreated obstructive sleep apnea (OSA) is associated with health comorbidities and negatively affects quality of life. Alternative treatments should be considered in patients who are unable to tolerate or benefit from positive airway pressure treatment. When properly indicated, positional devices, oral appliances, airway surgery, and hypoglossal nerve stimulation have been shown to be effective in treating OSA. Hypoglossal nerve stimulation is a successful second-line treatment with low associated morbidity and complication rate.

The Hypoglossal Nerve Stimulation as a Novel Therapy for Treating Obstructive Sleep Apnea-A Literature Review

Obstructive sleep apnea (OSA) is a common sleep disorder that affects all age groups and is associated with many co-morbid diseases (especially cardiovascular diseases). Continuous positive airway pressure (CPAP) is the gold standard for treating OSA. However, adherence to PAP therapy has been a major challenge with an estimated adherence between 20% and 80%. Mandibular advancement devices (MAD) are a good alternative option if used in the appropriate patient. MAD are most effective in mild and moderate OSA but not severe OSA. Surgical options are invasive, not appropriate for severe OSA, and associated with pain and long healing time. Hypoglossal nerve stimulation (HGNS), or upper airway stimulation (UAS), is a novel therapy in treating moderate and severe degrees of OSA in patients who cannot tolerate CPAP therapy. We reviewed the MEDLINE (PubMed) database. The search process yielded 303 articles; 31 met the inclusion and exclusion criteria and were included. We concluded that hypoglossal nerve stimulation is a very effective and novel alternative therapy for moderate and severe OSA in patients who cannot tolerate CPAP therapy. Adherence to HGNS is superior to CPAP. However, more developments are needed to ensure the highest safety profile.

Considering the Role of Adherence in New and Emerging Sleep Treatments

There are several novel and emerging treatments for obstructive sleep apnea (OSA), including new devices and pharmacotherapies. Long-term efficacy and adherence data for these interventions in the sleep context are lacking. Future studies exploring the long-term adherence and efficacy in novel and emerging treatments of OSA are required to fully understand the place of these treatments in treatment hierarchies. Such research also should aim to evaluate the use of these novel therapies in real-world clinical settings, because many of the studies performed to date have been done under closely monitored research populations and relatively small sample sizes.

Neurodevelopmental Disorders Commonly Presenting with Sleep Disturbances

There are multiple disorders of neurodevelopment that present with co-occurring sleep disturbances. Many of these neurodevelopmental disorders (NDD) include sleep disturbances in their diagnostic criteria. Neurobiological, genetic, and environmental factors overlap to cause different sleep disorders in individuals with NDD. Caregivers often present reporting either insomnia or hypersomnia, and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. It is crucial that clinicians understand the different presentations of sleep disturbances in individuals with NDD.

Die Stimulation des Nervus hypoglossus in der Behandlung der obstruktiven Schlafapnoe – Aktualisiertes Positionspapier der Arbeitsgemeinschaft Schlafmedizin der DGHNO-KHC

Hypoglossal nerve stimulation for obstructive sleep apnea - Updated position paper of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Since the first statement of the German Society of Oto-Rhino-Laryngology, hypoglossal nerve stimulation (HNS) is meanwhile an established treatment option for obstructive sleep apnea (OSA). There are three HNS systems available in Germany which differ in their technical details of the underlying comparable basic principle. For the unilateral HNS with respiratory sensing, several comparative studies, high-volume register analysis and long-term reports exist. The continuous HNS without respiratory sensing does not require a sleep endoscopy for indication. For the bilateral continuous HNS as the single partially implantable device, a feasibility study exists. For indication, the assessment of positive airway pressure failure by sleep medicine is crucial, and the decision for HNS should be made in discussion of other treatment options for at least moderate OSA. The implantation center holds primarily responsibility among the interdisciplinary sleep team and is primary contact for the patient in problems. This depicts why structural processes are required to secure outcome quality and minimize complications. The aftercare of HNS patients can be provided interdisciplinary and by different medical institutions whereat minimal reporting standards to document outcome and usage are recommended.

Adverse events associated with the Inspire implantable hypoglossal nerve stimulator: A MAUDE database review

BACKGROUND

Implantable hypoglossal nerve stimulation (HNS) has been found to be a safe and effective therapy for patients with obstructive sleep apnea, and patient adherence to treatment has been found to be as high as 86% after 12 months of therapy.

OBJECTIVE

The purpose of this study is to review the medical device reports (MDRs) submitted to the Food and Drug Administration's (FDA) Manufacturer and User Device Facility Experience (MAUDE) database to identify adverse events related to HNS therapy that could hinder compliance.

METHODS

A search of the FDA MAUDE database was conducted using the product code "MNQ" for "Inspire stimulator for sleep apnea." Reports of adverse events associated with Inspire for sleep apnea from January 2000 to May 2020 were included for analysis. From these included reports, event variables were collected, including event setting, adverse event to patient, iatrogenic injury, device malfunction, interventions, and root causes. Results were compiled and reviewed.

RESULTS

The search query yielded 180 reports that met inclusion criteria, containing a total of 196 adverse events. The most commonly reported adverse events to patients were infection (n = 50, 34.2%), neuropraxia (n = 22, 15.1%) and hematoma/seroma (n = 17, 11.6%). A total of 83 adverse events (42.3%) required reoperation. The most common reoperations performed for adverse events to patients were explantation (n = 30, 46.2%) and device repositioning/lead revision (n = 24, 36.9%), while the most common reoperation performed for device malfunctions was device replacement (n = 10, 55.6%).

CONCLUSION

In attempting to further improve patient compliance, understanding these device malfunctions and adverse events related to HNS implantation or usage is crucial for the identification of potential causes of patient non-adherence.

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.

Predictors of success in hypoglossal nerve stimulator implantation for obstructive sleep apnea

Objective

Current guidelines for hypoglossal nerve stimulator (HGNS) implantation eligibility include drug-induced sleep endoscopy (DISE) findings and other patient characteristics but lead to highly variable rates of surgical success across institutions. Our objective was to determine whether additional factors seen on preoperative evaluation could be used as predictors of surgical success.

Study design

Retrospective chart review.

Setting

Single-institution academic tertiary care medical center.

Subjects

and Methods:This study included patients with obstructive sleep apnea (OSA) who underwent HGNS implantation between 2015 and 2018. Surgical success was defined as a postoperative apnea-hypopnea index (AHI) of less than 20 events per hour and an AHI reduction of at least 50%. Preoperative polysomnogram (PSG) results, DISE findings, and physical parameters were compared between surgical successes and failures.

Results

A total of 68 patients were included in the analysis. The overall surgical success rate was 79.4% (54/68). Elevated preoperative AHI was associated with an increased likelihood of treatment failure, with an AHI of (36.9 ± 16.8) events/hour in the success group compared to (49.4 ± 19.6) events/hour in the failure group (P = 0.05). Patients observed to have partial lateral oropharyngeal collapse on DISE was more frequently associated with the treatment failure group than in the success group (P = 0.04).

Conclusion

Patients who underwent HGNS implantation overall had a very high treatment response rate at our institution. Factors that may predispose patients to surgical failure included the presence of lateral oropharyngeal collapse and a significantly elevated preoperative AHI. These should be considered when determining surgical candidacy for HGNS implantation.

Safety and effectiveness in explantation and re-implantation of hypoglossal nerve stimulation devices

PURPOSE

Since 2001, hypoglossal nerve stimulators have been implanted in patients with obstructive sleep apnea around the world, initially in trial situations but more recently also in regular care settings. Medium term data indicate effectiveness and tolerability of treatment. However, when assessing the safety of the procedure, the safe feasibility of explantation or reimplantation must also be considered.

PATIENTS AND METHODS

Nine patients with an implanted respiratory-driven hypoglossal nerve stimulator. We have evaluated the feasibility and safety of explantation or re-implantation with another stimulation system.

RESULTS

In 2012, nine patients were implanted with a respiratory-driven hypoglossal nerve stimulator as part of the Apnex Medical Pivotal Study. The study was ended in 2013. For a variety of reasons, the system was explanted from all nine patients by the year 2019. Three of these patients were re-implanted with a different system with respiratory sensing during the same session (mean incision to closure time for explantation 88.2 ± 35.01 min., mean incision to closure time for re-implantation 221.75 ± 52.73 min.). Due to extensive scar tissue formation, all procedures were technically challenging. Complication rate was significantly higher when re-implantation was performed or attempted in the same surgical session (0 of 5 patients with explantation versus 3 of 4 patients with attempted re-implantation; p = 0.018). There was no significant difference between the AHI values before and after implantation in patients with re-implantation.

CONCLUSION

Explantation and re-implantation are technically challenging though possible procedures. The single-staged equilateral reimplantation of another hypoglossal nerve stimulation system can, but need not, be successful.

Update on Research and Practices in Major Sleep Disorders: Part I. Obstructive Sleep Apnea Syndrome

PURPOSE

The purpose of this first of two review articles providing an update on sleep disorders was to examine the pathophysiology, epidemiology, and treatment of obstructive sleep apnea (OSA). OSA is a common sleep disorder whose prevalence is similar to asthma. As with other sleep disorders, OSA has a broad impact on individuals, affecting their daily behaviors, cognitive abilities, and performance, and putting them at increased risk for accidents, mood disorders, cancer, cardiovascular disease, and hypertension. Thus, early recognition and management, much of which can be implemented by nurses, can reduce health and accident risks and improve daily functioning.

METHODS

This narrative review utilized medical databases such as PubMed to identify relevant English language original and systematic review articles predominantly from peer-reviewed journals from 2012 to 2018. However, as background, findings from classic articles prior to 2012 were also included.

CLINICAL RELEVANCE

OSA is a common condition with considerable impact on daily functioning and potential for accidents and serious comorbidities such as hypertension, cardiovascular disease, diabetes, and depressed mood. The impairments and comorbidities associated with OSA can be reduced through early detection, encouraging treatment, providing education about sleep and OSA, and, importantly, promoting adherence to the predominant therapy, positive airway pressure.

Assessment and Management of Postoperative Pain Associated with Sleep Apnea Surgery

A literature review was conducted regarding the assessment and treatment of postoperative pain following surgery for obstructive sleep apnea (OSA). Given the risks of opioid use by patients with OSA, special attention to opioid risk reduction and avoidance is warranted in this population. The results of this review demonstrate the existence of a body of evidence that supports the use of nonopioid analgesics and nonpharmacologic approaches pain management. Strategies for managing postoperative pain should emphasize the use of local anesthetic infiltration, nonsteroidal antiinflammatory drugs, acetaminophen, topical analgesics, surgical wound cooling, and when necessary, safer opioid medications, such as tramadol and intranasal butorphanol.

Electrical stimulation as a therapeutic approach in obstructive sleep apnea - a meta-analysis

PURPOSE

Electrical stimulation of the upper airway dilator muscles is an emerging treatment for obstructive sleep apnea (OSA). Invasive hypoglossal nerve stimulation (HNS) has been accepted as treatment alternative to continuous positive airway pressure (CPAP) for selected patients, while transcutaneous electrical stimulation (TES) of the upper airway is being investigated as non-invasive alternative.

METHODS

A meta-analysis (CRD42017074674) on the effects of both HNS and TES on the apnea-hypopnea index (AHI) and the Epworth Sleepiness Scale (ESS) in OSA was conducted including published evidence up to May 2018. Random-effects models were used. Heterogeneity and between-study variance were assessed by I² and τ², respectively.

RESULTS

Of 41 identified clinical trials, 20 interventional trials (n = 895) could be pooled in a meta-analysis (15 HNS [n = 808], 5 TES [n = 87]). Middle-aged (mean ± SD 56.9 ± 5.5 years) and overweight (body mass index 29.1 ± 1.5 kg/m²) patients with severe OSA (AHI 37.5 ± 7.0/h) were followed-up for 6.9 ± 4.0 months (HNS) and 0.2 ± 0.4 months (TES), respectively. The AHI improved by - 24.9 h^-1 [95%CI - 28.5, - 21.2] in HNS (χ² 79%, I² 82%) and by - 16.5 h^-1 [95%CI - 25.1, - 7.8] in TES (χ² 7%, I² 43%; both p < 0.001). The ESS was reduced by - 5.0 (95%CI - 5.9, - 4.1) (p < 0.001).

CONCLUSION

Both invasive and transcutaneous electrical stimulation reduce OSA severity by a clinically relevant margin. HNS results in a clinically relevant improvement of symptoms. While HNS represents an invasive treatment for selected patients with moderate to severe OSA, TES should be further investigated as potential non-invasive approach for OSA.

Preoperative Predictors of Response to Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea

Objective

Hypoglossal nerve stimulation (HGNS) is an effective treatment for patients with obstructive sleep apnea (OSA) who fail continuous positive airway pressure (CPAP). We assessed the relationship between patient characteristics and response to HGNS.

Study Design

Retrospective cohort study.

Setting

Single tertiary care institution.

Subjects and Methods

This study included CPAP-intolerant patients with moderate to severe OSA after HGNS system implantation from November 2015 to December 2017. Patient measures, drug-induced sleep endoscopy (DISE) findings, and apnea-hypopnea indices (AHIs) were recorded.

Results

Forty-eight patients underwent implantation with the following median measures: age, 66 years; body mass index, 28.6; and neck circumference, 41.0 cm. Patients were classified by Friedman tongue position (II, 27%; III, 56%; IV, 17%) and Mallampati grade (I, 25%; II, 50%; III, 23%; IV, 2%). By DISE, 71% had anterior-posterior palatal collapse. Additionally, 38% had lateral oropharynx collapse; 50%, tongue base collapse; and 27%, epiglottis collapse. Following implantation, median AHI improved from 38.5 to 2.7 ( P < .001), and 92% of patients had no worse than mild OSA (8% moderate). Patients with Friedman tongue position grade II/III experienced greater change in AHI as compared with grade IV (94.2% vs 73.8%, P < .001). Patients with Mallampati score I/II experienced greater improvement versus score III/IV (94.7% vs 66.5%, P < .001). No DISE findings, including any obstruction or collapse, were associated with change in AHI.

Conclusion

This study further confirms HGNS as an effective treatment of CPAP-intolerant OSA. Office measures such as Friedman tongue position IV and Mallampati III/IV were associated with mildly decreased response. DISE findings were not associated with patient response.

Bilateral hypoglossal nerve stimulation for treatment of adult obstructive sleep apnoea

BACKGROUND AND AIM

Hypoglossal nerve stimulation (HNS) decreases obstructive sleep apnoea (OSA) severity via genioglossus muscle activation and decreased upper airway collapsibility. This study assessed the safety and effectiveness at 6 months post-implantation of a novel device delivering bilateral HNS via a small implanted electrode activated by a unit worn externally, to treat OSA: the Genio™ system.

METHODS

This prospective, open-label, non-randomised, single-arm treatment study was conducted at eight centres in three countries (Australia, France and the UK). Primary outcomes were incidence of device-related serious adverse events and change in the apnoea-hypopnoea index (AHI). The secondary outcome was the change in the 4% oxygen desaturation index (ODI). Additional outcomes included measures of sleepiness, quality of life, snoring and device use. This trial was registered with ClinicalTrials.gov, number NCT03048604.

RESULTS

22 out of 27 implanted participants (63% male, aged 55.9±12.0 years, body mass index (BMI) 27.4±3.0 kg·m^-2) completed the protocol. At 6 months BMI was unchanged (p=0.85); AHI decreased from 23.7±12.2 to 12.9±10.1 events·h^-1, a mean change of 10.8 events·h^-1 (p<0.001); and ODI decreased from 19.1±11.2 to 9.8±6.9 events·h^-1, a mean change of 9.3 events·h^-1 (p<0.001). Daytime sleepiness (Epworth Sleepiness Scale; p=0.01) and sleep-related quality of life (Functional Outcomes of Sleep Questionnaire-10; p=0.02) both improved significantly. The number of bed partners reporting loud, very intense snoring, or leaving the bedroom due to participant snoring decreased from 96% to 35%. 91% of participants reported device use >5 days per week, and 77% reported use for >5 h per night. No device-related serious adverse events occurred during the 6-month post-implantation period.

CONCLUSIONS

Bilateral HNS using the Genio™ system reduces OSA severity and improves quality of life without device-related complications. The results are comparable with previously published HNS systems despite minimal implanted components and a simple stimulation algorithm.

Electrical stimulation of the whole hypoglossal nerve in patients with obstructive sleep apnea

PURPOSE

Electrical stimulation of the whole hypoglossal nerve (HGp-ES) has been demonstrated to enlarge the pharynx and improve pharyngeal stability and patency to airflow in all animals studied, but not in humans. The present study was undertaken to better understand the effect of HGp-ES on the human pharynx.

METHODS

Eight patients with obstructive sleep apnea who had implanted stimulators with electrodes positioned proximally on the main truck of the hypoglossus were studied under propofol sedation. Pharyngoscopy and air flow measurements at multiple levels of continuous positive airway pressure (CPAP) were performed before and during Hgp-ES.

RESULTS

HGp-ES that activates both tongue protrusors and retractors narrowed the pharyngeal lumen at the site of collapse (velopharynx in all subjects) from 1.38 ± 0.79 to 0.75 ± 0.44 cm², p < 0.05 (measured at mid-range of CPAP levels) and lowered airflow (from 8.88 ± 2.08 to 6.69 ± 3.51 l/min, p < 0.05). Changes in critical pressure (Pcrit) and velopharyngeal compliance were not significant, but oropharyngeal compliance decreased (from 0.43 ± 0.18 to 0.32 ± 0.13 cm²/cmH2O, p < 0.05). No correlation was found between the pattern of change in luminal shape (determined as the ratio of a-p vs. lateral diameter when lowering CPAP) or changes in cross-sectional area and airflow during Hgp-ES.

CONCLUSIONS

Our findings indicate that human retractors dominate when stimulated together with the protrusors during HGp-ES. While co-activation of retractors may be beneficial, it should be limited. We speculate that exercises that augment protrusor force may improve the response to hypoglossal stimulation. The exclusion of patients with concentric pharyngeal obstruction should be re-evaluated.

Hypoglossal Nerve Stimulation in the Treatment of Obstructive Sleep Apnea: Patient Selection and New Perspectives

Hypoglossal nerve stimulation (HNS) is an increasingly widespread OSA treatment. It is a non-anatomical modifying surgery able to achieve an adequate objective and subjective result with a reasonable complication rate. HNS exploits the neurostimulation to reduce upper airway collapsibility providing a multilevel upper airway improvement within a single procedure. Proper patient selection has a fundamental role in determining an adequate long-term clinical outcome. All patient candidates for HNS undergo a standard comprehensive sleep medicine assessment and upper airway surgical examination. Several features should be assessed preoperatively in order to predict patients' response to HNS treatment. In particular, the assessment of OSA severity, BMI > 32 Kg/m², collapse pattern during drug-induced sleep endoscopy (DISE), and many other parameters, is central for a good patient selection and customization of OSA treatment. HNS is indeed one of the most promising tools in the widespread context of personalized sleep medicine. HNS is an adjustable medical device that could be titrated in order to improve HNS effectiveness, maintaining patient comfort. Moreover, HNS provides the opportunity for patients to play an active role in their own care, with a potential improvement in therapy adherence and efficacy. This review summarizes the current evidence in patient selection for HNS, highlighting the reasons behind the optimistic future of this OSA treatment in the context of personalized medicine.

[Stimulation for sleep apnea : Targeting the hypoglossal nerve in the treatment of patients with OSA]

Standard treatment of obstructive sleep apnea (OSA) is nightly application of positive airway pressure therapy (CPAP). However, adherence to CPAP is limited due to side effects and complications, and patients are frequently untreated or undertreated. In this scenario, patients with OSA are at risk of developing comorbidities such as arterial hypertension, coronary artery disease, or diabetes, and are exposed to an increased risk of experiencing traffic or occupational accidents due to daytime sleepiness. Alternative treatments include mandibular advancement devices or positional devices to prevent patients sleeping on their back, as well as anatomy-altering surgical procedures. For several years now, an additional surgical treatment-hypoglossal nerve stimulation-has been available for selected OSA patients. Hypoglossal nerve stimulation is a dynamic surgical approach that uses electrical stimulation to activate key muscles of the upper airway to achieve airway patency.