Updates of operative techniques for upper airway stimulation

Neurostimulation for Obstructive Sleep Apnea

Neurostimulation of hypoglossal nerve has emerged as an effective treatment option of obstructive sleep apnea (OSA). Since FDA approval in 2014, therapy has been widely used in select patients with moderate-to-severe OSA who do not benefit from positive airway pressure. Ongoing research and technological developments continue to advance the therapy to deliver personalized and efficient treatment to patients with OSA.

Upper Airway Stimulation in Female Patients: Safety and Efficacy of a Novel Lateral Approach

OBJECTIVE

To describe a novel lateral approach for hypoglossal nerve stimulator (HNS) implantation in women and provide evidence for its safety and efficacy.

STUDY DESIGN

Retrospective case series.

SETTING

Single academic medical center.

METHODS

We identified patients implanted with HNS by a single surgeon from January 2017 to December 2021. Patient characteristics, postoperative complications, surgical duration, response to therapy, and need for revision surgery were recorded.

RESULTS

One hundred four patients were included, including 93 males and 11 females. The lateral approach for HNS implantation involves placing the chest incision for the implantable pulse generator and respiratory sensor lead vertically in the anterior axillary line instead of horizontally in the infraclavicular area. No changes are made to the stimulator lead placement. All female patients were implanted using a lateral approach and all male patients were implanted via the standard anterior approach. Half of the patients were implanted via a 2-incision technique. The median surgical time duration was equivalent in male and female patients (119 [interquartile range (IQR): 105-138] vs 126 [IQR: 115-141], respectively). Revision was required in 2 (18%) females versus 6 (6%) males (p = .17). There were equivalent rates of therapy response as well as postoperative complications.

CONCLUSION

A more cosmetic lateral approach is feasible for HNS in female patients and has a similar rate of adverse events and therapy responsiveness. Additional considerations in female patients include the ability to tolerate mammography as well as HNS implantation in the setting of existing breast implants.

Electric field aspects in hypoglossal nerve stimulation for obstructive sleep apnea: A bilateral electrophysiological evaluation of unilateral electrode configuration changes

Hypoglossal nerve stimulation is an established treatment option for obstructive sleep apnea in selected patients. A unilateral hypoglossal nerve stimulation system was approved a decade ago, yet the physiological effect of unilateral hypoglossal stimulation on bilateral tongue motion remains unclear. This study examined how electrode configuration, stimulation cuff position, or body mass index influenced the contralateral genioglossus electromyography (EMG) signal. Twenty-nine patients underwent three EMG recordings in a polysomnographic setting after being implanted with a unilateral hypoglossal nerve stimulator for at least 6 months. The ratio of EMG signals between the ipsi- and contralateral sides was evaluated. No difference in EMG signals was demonstrated based on electrode configurations, stimulation-cuff position, body-mass-index, or sleep apnea severity, even in patients with right tongue protrusion only. Our findings may be explained by a significant level of cross-innervation and by a smaller and less variable circumferential electric field than expected based on prior biophysical models. A patient's individual anatomy needs to be considered during therapy titration in order to achieve an optimal response.

Home sleep apnea testing with peripheral arterial tonometry to assess outcome in upper airway stimulation

STUDY OBJECTIVES

To determine whether home sleep apnea testing with peripheral arterial tonometry (HSAT-PAT) can be used in upper airway stimulation to evaluate therapy success.

METHODS

Data analysis from 50 consecutive patients receiving upper airway stimulation was performed. Baseline values were measured by polysomnography and HSAT-PAT. Follow-up was performed during and after titration (3-6 months) by polysomnography and HSAT-PAT and after 1 year by HSAT-PAT only. Primary outcome measures were reduction in the apnea-hypopnea index and oxygen desaturation index. In addition, an analysis of night-to-night variability for HSAT-PAT was performed.

RESULTS

All 50 patients completed their posttitration visit (3-6 months) and 41 patients completed the 1-year follow-up. In HSAT-PAT after 1 year, the mean apnea-hypopnea index (desaturation 3%) was reduced from 29.5 ± 17.1 events/h to 19.9 ± 13.1 events/h (P < .01) and the oxygen desaturation index (desaturation 4%) was reduced from 17.8 ± 12.6 events/h to 10.2 ± 8.3 events/h (P < .01). Therapy adherence after 1 year was high (6.6 ± 1.9 hours per night) and led to improvement in daytime sleepiness, meaning a reduction in the Epworth Sleepiness Scale score from 12.8 ± 5.4 to 5.9 ± 4.0 (P < .01). Analysis of night-to-night variability showed similar apnea-hypopnea index values between the 2 nights.

CONCLUSIONS

Upper airway stimulation was able to reduce the apnea-hypopnea index and oxygen desaturation index after 1 year, as assessed by full-night efficacy studies with HSAT-PAT. In addition, improvements in self-reported outcome parameters were observed. The importance of publishing the scoring criteria is highlighted and whether data are based on full-night efficacy studies or a selected period of time from a sleep study. This is a prerequisite for comparing data with other trials in the emerging field of upper airway stimulation.

CITATION

Hinder D, Schams SC, Knaus C, Tschopp K. Home sleep apnea testing with peripheral arterial tonometry to assess outcome in upper airway stimulation. J Clin Sleep Med. 2022;18(9):2197-2205.

Efficacy of expansion pharyngoplasty and hypoglossal nerve stimulation in treating sleep apnea

OBJECTIVE

We investigated whether a palatal conversion procedure combined with a second-stage hypoglossal nerve stimulator (HGNS) insertion can be beneficial for those patients who have a complete concentric velopharyngeal collapse and may initially not meet the criteria for use of HGNS.

METHODS

A retrospective chart review included all patients who underwent a planned multi-level sleep surgery including expansion sphincter pharyngoplasty (ESP) followed by HGNS. All patients had a complete concentric collapse (CCC) of the velopharynx (VP) on pre-intervention drug-induced sleep endoscopy (DISE) and were initially not a candidate for HGNS. These patients then underwent ESP followed by a DISE to confirm elimination of the CCC of the VP. They then went on to HGNS implantation several months later followed by a sleep study.

RESULTS

A total of 20 patients were identified and included in the retrospective chart analysis. All patients who underwent ESP successfully converted their VP from CCC to an anterior-posterior collapse pattern and thus met inclusion criteria for HGNS. After the HGNS was implanted, patients showed a significant reduction of the mean AHI from 53.9 before ESP to 8.2 after ESP and HGNS and a decrease in the Epworth Sleep Score (ESS) from a mean of 13.3 to 5.7.

CONCLUSION

ESP can be effective in eliminating the CCC of the VP thus making patients become HGNS candidates. In selected OSA patients, who have multilevel upper airway obstruction with complete concentric VP collapse, the combination of ESP and HGNS insertion should be considered as a planned 2-staged approach.

LEVEL OF EVIDENCE: 4

Hypoglossal nerve stimulation versus positive airway pressure therapy for obstructive sleep apnea

Purpose

Hypoglossal nerve stimulation (HNS) has been shown to treat obstructive sleep apnea (OSA) effectively. The aim of this study was to compare HNS with positive airway pressure (PAP) treatment regarding outcome parameters: (1) sleepiness, (2) apnea–hypopnea index (AHI), and (3) effectiveness.

Methods

Propensity score matching with nearest neighbor algorithm was used to compare outcomes of HNS and PAP therapy in a real-world setting. Data were collected at baseline and 12 months after initiating OSA treatment including demographics, Epworth Sleepiness Scale (ESS), AHI, and objective adherence data. To account for overall treatment efficacy, the mean disease alleviation (MDA) was calculated.

Results

Of 227 patients who received treatment consecutively, 126 could be matched 1:1 with regard to age, body mass index, and AHI. After matching, no statistically significant differences between the groups were found. A clinically important symptom improvement was seen at 12 months in both cohorts, though there was a greater difference in ESS improvement in patients treated with HNS (8.0 ± 5.1 points vs. 3.9 ± 6.8 points; p = 0.042). In both groups, mean posttreatment AHI was significantly reduced (HNS: 8.1 ± 6.3/h; PAP: 6.6 ± 8.0/h; p < 0.001). Adherence after 12 months among patients treated with HNS was higher than in those receiving PAP therapy (5.0 ± 2.6 h/night; 4.0 ± 2.1 h/night) but not with statistical significance. Overall effectiveness calculated with the MDA was 59% in patients treated with HNS compared to 51% receiving PAP.

Conclusion

Patients treated with HNS therapy had significantly greater improvements in daytime sleepiness compared to PAP therapy, while the mean reduction of AHI and overall effectiveness were comparable for both treatments.

Trial registration

ClinicalTrial.gov Identifier: NCT03756805.

Bilateral vs Unilateral Hypoglossal Nerve Stimulation in Patients With Obstructive Sleep Apnea

Objective

Unilateral hypoglossal nerve stimulation (uniHNS) is an effective treatment for obstructive sleep apnea. Bilateral hypoglossal nerve stimulation (biHNS) is a novel therapeutic option and a different approach to hypoglossal nerve stimulation. The aim of this study was to analyze the clinical outcome of the first 10 biHNS cases vs the first 10 uniHNS cases ever implanted.

Study Design

Prospective data analysis.

Setting

International multicenter comparative clinical trial.

Methods

The first 10 patients in 2020 who received a biHNS device (Genio System; Nyxoah) and the first 10 patients in 2014 who received a uniHNS system (Inspire II; Inspire Medical Systems) were included. Treatment outcome was evaluated at 3 months after surgery. Data collection included demographics, apnea hypopnea index (AHI), oxygen saturation and desaturation index, Epworth Sleepiness Scale, and adverse events.

Results

The mean ± SD age was 52.1 ± 9.6 years (biHNS) and 58.3 ± 8.6 years (uniHNS). The mean body mass index was 26.4 ± 5.6 kg/m² (biHNS) and 26.2 ± 2.2 kg/m² (uniHNS). The mean preimplantation AHI (biHNS, 39.9 ± 14.8/h; uniHNS, 32.2 ± 11.0/h) decreased in both groups after 3 months (biHNS, 19.2 ± 14.0/h, P = .008; uniHNS, 13.1 ± 16.8/h, P = .037) with no significant difference between groups (P = .720). The mean preimplantation Epworth Sleepiness Scale (biHNS, 11.8 ± 6.2; uniHNS, 11.1 ± 4.9) decreased as well after 3 months (biHNS, 9.4 ± 6.3; uniHNS, 6.0 ± 5.0).

Conclusion

Preliminary postmarket data suggest that biHNS may be as safe and effective as uniHNS. Long-term follow-up in a larger sample size is required to assess the stability of biHNS.

Two-Incision Approach for Hypoglossal Nerve Stimulator Placement: A Single Institution Assessment

OBJECTIVE(S)

Upper airway stimulator (UAS) placement is a treatment for obstructive sleep apnea (OSA) with few complications and low morbidity. UAS placement has traditionally been performed using a three-incision approach, however, it has been implanted using a two-incision approach. This approach could significantly decrease operation time without a difference in postoperative complications, demonstrating its safety and feasibility for UAS placement. The objective was to assess operative time and complication rate in the two-incision approach for UAS placement compared to the three-incision approach.

STUDY DESIGN

Retrospectively reviewed.

METHODS

Patients who underwent UAS placement using the two- or three-incision approach at a single academic institution from November 2014 to June 2021 were retrospectively reviewed. The two-incision approach did not include the incision at the mid-axillary line. Main outcome measures included operation time and complication rates.

RESULTS

Three-hundred forty-eight patients underwent UAS placement. The three-incision approach demonstrated an average operation time of 143.3 minutes whereas the two-incision approach averaged 129.4 minutes (P < .001). There was no significant difference in rate of postoperative complications between the two- and three-incision cohorts including pneumothorax (0% vs. 0.4%, P > .99), patient-reported discomfort (5.6% vs. 6.5%, P > .99), activity restriction (0% vs. 1.4%, P > .50), and incisional pain (0.0% vs. 1.0%, P > .99). No patients experienced incision site bleeding or infection. The two-incision approach was associated with decreased rate of revision surgery (0.0% vs. 5.4%, P = .048).

CONCLUSION

The UAS two-incision approach proved to have a significantly shorter operative time without an increase in complications as compared to the three-incision approach. This approach is a safe and feasible option.

LEVEL OF EVIDENCE

III Laryngoscope, 2022.

Persistent Treatment-Emergent Central Sleep Apnea (TECSA) Following Hypoglossal Nerve Stimulation

PURPOSE

Since 2001, hypoglossal nerve stimulators (HNS) have been used worldwide to treat patients with obstructive sleep apnea (OSA). Recently, a few studies reported treatment-emergent central sleep apnea (TECSA) with spontaneous resolution following HNS. However, the evidence of persistent development of TECSA during long-term care visits was lacking. As a result, this study first report two patients with persistent TECSA and describe their development phenotype during more than two years of follow-up visits to help explore the influencing factors and underlying mechanisms.

PATIENTS AND METHODS

This retrospective study included twenty-seven patients who underwent HNS implantation from 2016 to 2021. Their demographic data, pre- and postoperative sleep study characteristics, and device use settings were collected. The possible factors associated with post-operative elevated CSA (central apnea index ≥5) were evaluated. Moreover, the development phenotype of the TECSA was observed and followed up with a titration trial study.

RESULTS

Among overall 27 patients with OSA, 3 patients with an increased preoperative Epworth Sleepiness Score (ESS) got an elevated CSA (CAI ≥ 5). Two of these 3 patients developed a persistent TECSA with a significant negative correlation between obstructive apnea index (OAI) and central and mixed sleep apnea index (CMAI) (R = -0.745, P = 0.021). These development phenotypes might be associated with different stimulation amplitudes of the HNS device. Furthermore, the following titration trial study also suggested that different amplitudes would influence the development of TECSA following HNS.

CONCLUSION

OSA patients with severe daytime sleepiness are more likely to have elevated CSA following HNS. An inappropriate stimulation amplitude might influence the development course of TECSA in such patients.

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.

Neurophysiological profiles of responders and non-responders to hypoglossal nerve stimulation: a single institution study

STUDY OBJECTIVES

Hypoglossal nerve stimulation (HGNS) is an effective alternative treatment for obstructive sleep apnea (OSA) that acts by opening the airway via selective stimulation of nerve fibers that innervate tongue muscles that protrude (genioglossus) and stiffen the tongue (transverse and vertical) while avoiding nerve fibers that innervate tongue muscles that retract the tongue (styloglossus and hyoglossus). There remains a subset of post-operative patients who fail to adequately respond to HGNS, in some cases due to simultaneous mixed activation of muscles that protrude and retract the tongue. This study aims to characterize the relationship between neurophysiological data from individual tongue muscle activation during intraoperative electromyographic (EMG) recordings and post-operative AHI responses to HGNS..

METHODS

A single institution review of 46 patients undergoing unilateral HGNS implantation for OSA. Patients were separated into responders and non-responders through comparison of pre and postoperative AHI. Neurophysiological data included EMG responses of the genioglossus, styloglossus/hyoglossus, intrinsic/vertical, and hyoglossus (neck) muscles to intraoperative stimulation using unipolar (--- and o-o) and bipolar (+-+) settings.

RESULTS

The overall treatment success rate was 61% as determined by a post-operative AHI <20 events/hr with a greater than 50% AHI reduction. We observed no statistically significant relationships between treatment response and individual muscle responses. However, we did note that increasing BMI was correlated with worse post-operative responses.

CONCLUSIONS

Although we noted a significant sub-group of clinical non-responders to HGNS post-operatively, these patients were not found to exhibit significant inclusion of tongue retractors intraoperatively on neurophysiological analysis. Further research is needed to delineate additional phenotypic factors that may contribute to HGNS treatment responses.

Implantation of the hypoglossal nerve stimulator via left sided, 2-incision approach

This is a case series of 5 patients who underwent implantation of the hypoglossal nerve stimulator for obstructive sleep apnea via a left-sided, two incision technique. This represents a significant modification of the original right-sided, three-incision technique. All five patients were successfully implanted with this technique variant with no adverse events or negative impact on device functionality, such as cardiac artifact.

A Noninferiority Analysis of 3- vs 2-Incision Techniques for Hypoglossal Nerve Stimulator Implantation

OBJECTIVE

The only hypoglossal nerve stimulation (HNS) device available for US clinical use is implanted through 3 incisions. A recently proposed 2-incision modification moved the respiratory sensing lead from the fifth to the second intercostal space to eliminate the third lower chest incision. This study compared perioperative data and therapeutic outcomes between the techniques.

STUDY DESIGN

Noninferiority cohort analysis of a retrospective and prospective registry study.

SETTING

Tertiary care and community surgical centers.

METHODS

Patients with obstructive sleep apnea underwent HNS implantation via a modified 2-incision technique (I₂). A cohort previously implanted via the standard 3-incision technique (I₃) were 1:1 propensity score matched for a noninferiority analysis of postoperative outcomes.

RESULTS

There were 404 I₃ patients and 223 I₂ patients across 6 participating centers. Operative time decreased from 128.7 minutes (95% CI, 124.5-132.9) in I₃ patients to 86.6 minutes (95% CI, 83.7-97.6) in I₂ patients (P < .001). Postoperative sleep study data were available for 76 I₂ patients who were matched to I₃ patients. The change in apnea-hypopnea index between the cohorts was statistically noninferior (a priori noninferiority margin: 7.5 events/h; mean difference, 1.51 [97.5% CI upper bound, 5.86]). There were no significant differences between the cohorts for baseline characteristics, perioperative adverse event rates, or change in Epworth Sleepiness Score (P > .05).

CONCLUSION

In a multicenter registry, a 2-incision implant technique for a commercially available HNS device had a statistically noninferior therapeutic efficacy profile when compared with the standard 3-incision approach. The 2-incision technique is safe and effective for HNS implantation.

Ultrasound Shear Wave Elastography of the Tongue during Selective Hypoglossal Nerve Stimulation in Patients with Obstructive Sleep Apnea Syndrome

Currently, there is no established technique to directly measure extrinsic tongue muscle activation during selective hypoglossal stimulation therapy (sHNS) in patients with obstructive sleep apnea syndrome (OSAS) in a simple, non-invasive clinical setting. Ultrasound shear-wave elastography (US-SWE) enables quantitative measurement of tissue stiffness. We investigated whether US-SWE is able to detect changes in muscle stiffness of the tongue during sHNS. Patients with OSAS treated with sHNS were prospectively enrolled. A standardized US-SWE protocol was used to selectively measure tissue stiffness of the geniohyoid muscle (GH) and genioglossus (GG) muscles on the side of stimulator implantation (sGH, sGG) and on the contralateral side (nGH, nGG) without and with sHNS. Eighteen patients were included (median age = 62 years, interquartile range: 56-65, 83.3% male). Median shear-wave velocity (SWV) increased during contraction with each patient's clinically prescribed therapeutic regimen in the sGH (+19%, p = 0.020) and sGG (+81%, p < 0.001) and decreased during contraction in the nGH (-8%, p = 0.107) and nGG (-8%, p = 0.396). Differences in SWV during contraction were significant only on the side of stimulation (sGG +81%, sGH +19%). SWE measurements had excellent reliability as reflected by a Cronbach α value ≥0.9 for all target muscles pre- and post-contraction and an item-total correlation ≥0.5. US-SWE allows reliable measurement of SWV as an indicator of muscle stiffness of extrinsic tongue muscles. This non-invasive method provides new possibilities to distinguish and characterize responders from non-responders in hypoglossal stimulation therapy. Compared with the regular visual assessment of tongue movement, US-SWE of individual muscle groups provides a new non-invasive imaging tool in patients with OSAS.

Upper airway stimulation: Fewer complications, ED presentations, readmissions, and increased surgical success

OBJECTIVES

Evaluate the rate of complications, readmissions, emergency department presentations, and surgical success rates amongst three standard surgical treatment options for obstructive sleep apnea: upper airway stimulation, transoral robotic surgery, and expansion sphincter pharyngoplasty.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary care center.

METHODS

Patients were included who were aged ≥18 years old and underwent upper airway stimulation, transoral robotic surgery, or expansion sphincter pharyngoplasty between January 2011 and May 2020.

RESULTS

345 patients were identified: 58% (n = 201) underwent upper airway stimulation, 10% (n = 35) underwent transoral robotic surgery, and 32% (n = 109) patients underwent expansion sphincter pharyngoplasty. There were 22 emergency department presentations and 19 readmissions, most of which were experienced by patients receiving transoral robotic surgery (six emergencies, seven readmissions) and expansion sphincter pharyngoplasty (12 emergencies, 11 readmissions). Patients with upper airway stimulation had four emergencies and one readmission. Only 2% of the upper airway stimulation cohort had a complication, whereas this was 20% and 12% for the transoral robotic surgery and expansion sphincter pharyngoplasty cohorts, respectively. Patients experienced the highest surgical success rate with upper airway stimulation (69%), whereas patients who received transoral robotic surgery and expansion sphincter pharyngoplasty had success rates of 50% and 51%, respectively.

CONCLUSION

Treating obstructive sleep apnea with upper airway stimulation led to lower rates of complications, emergency department presentations, and readmissions in this series. In those for whom upper airway stimulation is appropriate, it may be more effective in successfully treating obstructive sleep apnea than transoral robotic surgery and expansion sphincter pharyngoplasty.

Upper Airway Stimulation versus Untreated Comparators in Positive Airway Pressure Treatment-Refractory Obstructive Sleep Apnea

Rationale: Understand the impact of insurance coverage on sleep apnea outcomes for patients awaiting upper airway stimulation.Objectives: Examine the natural history of impact of upper airway stimulation treatment versus insurance denial (comparators) on sleep apnea outcomes.Methods: A parallel-arm experimental study design was used to compare objective sleep apnea measures and patient-reported outcomes in those who received upper airway stimulation approval versus denial in a multinational prospective study (NCT02907398). Wilcoxon rank-sum test and logistic regression models were used to assess for differences of objective and subjective outcome changes in those who underwent upper airway stimulation versus no treatment comparators.Results: A greater reduction in apnea-hypopnea index was observed in those who underwent upper airway stimulation (n = 230, follow-up: 360 ± 171 d) versus no treatment (n = 100, follow-up: 272 ± 278 d), that is, -19.1 ± 15.8 versus -8.1 ± 20.9, respectively, P < 0.001, with consistent findings observed with nocturnal hypoxia measures. Concordantly, a greater improvement noted with subjective measures of dozing propensity was observed in patients undergoing upper airway stimulation versus comparators (Epworth Score, -5.1 ± 5.5 vs. 1.8 ± 3.7, respectively, P < 0.001) and overall sleep-related patient-reported outcomes. Women and those with previous oral appliance use had a lower odds of insurance approval (odds ratio [OR], 0.40; 95% confidence interval [95% CI], 0.22-0.71 and OR, 0.35; 95% CI, 0.18-0.69, respectively).Conclusions: Objective and subjective sleep apnea burden was more improved in those receiving upper airway stimulation versus not. Results underscore the need to optimize clinical care pathways focused on effective treatment of patients with obstructive sleep apnea who are not upper airway stimulation-insurance eligible and prioritize public health policy initiatives to address insurance-based sex-specific disparities.

Improving outcomes of hypoglossal nerve stimulation therapy: current practice, future directions and research gaps. Proceedings of the 2019 International Sleep Surgery Society Research Forum

Hypoglossal nerve stimulation (HGNS) has evolved as a novel and effective therapy for patients with moderate-to-severe obstructive sleep apnea (OSA). Despite positive published outcomes of HGNS, there exist uncertainties regarding proper patient selection, surgical technique, and the reporting of outcomes and individual factors that impact therapy effectiveness. According to current guidelines, this therapy is indicated for select patients, and recommendations are based on the Stimulation Therapy for Apnea Reduction (STAR) trial. Ongoing research and physician experiences continuously improve methods to optimize the therapy. An understanding of the way in which airway anatomy, OSA phenotypes, individual health status, psychological conditions and comorbid sleep disorders influence the effectiveness of HGNS is essential to improve outcomes and expand therapy indications. This manuscript presents discussions on current evidence, future directions, and research gaps for HGNS therapy from the 10th International Surgical Sleep Society expert research panel.

Optimization of Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea With Ultrasound Assessment of Tongue Movement

BACKGROUND

Hypoglossal nerve stimulation (HGNS) is an Food and Drug Administration-approved therapy for obstructive sleep apnea. Initial programming of HGNS is based on the observation of anterior tongue movement, which may not reflect opening at the retroglossal airway. We developed an ultrasonographic technique to assess the base of tongue movement with HGNS to be used to optimize the initial voltage settings.

STUDY QUESTION

This study aimed to investigate the use of ultrasound to assess tongue movement with HGNS and related this measure to the apnea hypopnea index (AHI) on subsequent home sleep apnea testing or in-laboratory polysomnography with therapy.

STUDY DESIGN

Seventeen subjects (n = 17) implanted with HGNS were enrolled at least 1 month postimplantation. Ultrasonographic measures were then used to optimize HGNS voltage to produce observable base of tongue protrusion without producing discomfort. Responders were defined as a reduction in AHI > 50% and an AHI of <20 events/h.

RESULTS

There were 17 subjects, 11 men and 6 women, with age = 64.6 ± 9.8 years, body mass index = 27.9 ± 2.7 kg/m2, and pretreatment AHI = 36.5 ± 14.4/h, T-90% = 10.7 ± 14.8%. The mean hyoid bone excursion (HBE) in responders = 1.0 ± 0.13 cm versus 0.82 ± 0.12 cm in nonresponders (P = 0.017). HBE was correlated with AHI during HGNS treatment (coef. -0.54, P = 0.03). Best subsets regression analysis using treatment-based AHI as the dependent variable and age, body mass index, baseline AHI, HBE, and HGNS voltage as independent variables showed that HBE (coef. -44.6, P = 0.044) was the only independent predictor of response. Receiver operator curve analysis showed that HBE > 0.85 cm had a sensitivity of 83.3% and specificity of 80.0% with a positive likelihood ratio of 4.17 to predict responder status.

CONCLUSION

We demonstrated that ultrasound assessment of HBE during HGNS programming is a useful tool to optimize therapy.

Muscle type of palatopharyngeal muscle in children with severe obstructive sleep apnea

STUDY OBJECTIVES

To investigate the fiber-type distribution in palatopharyngeal muscle via adenosine triphosphatase and quantitative real-time polymerase chain reaction in children with severe obstructive sleep apnea (OSA).

METHODS

Study participants were 12 children with severe OSA and 15 children with simple snoring as the control group. Both groups were diagnosed by polysomnography and treated with tonsillectomy. The samples of palatopharyngeus muscle were studied under adenosine triphosphatase staining and quantitative real-time polymerase chain reaction to classify the different fiber types.

RESULTS

There were no differences in baseline age, body mass index, tonsil size, or sleep stage constitution between the 2 groups. Dominance (>60%) of type I fiber was observed both in children with simple snoring (3/15, 20%) and in those with severe OSA (1/12, 8.3%) via adenosine triphosphatase staining. Predominance of type II fibers was seen in 3/15 (20%) in the control group and 6/12 (50%) in the severe OSA group, respectively. Type grouping was also seen in 8/15 (53.3%) in non-OSA and 6/12 (50%) in severe OSA groups, respectively. There was no difference in distribution of subtype fibers assessed by quantitative real-time polymerase chain reaction between the 2 groups; the mean percentages of type I fibers were 25.8% ± 19.5% and 20.9% ± 16.6%, respectively (P > .05), similar to type IIa fibers (35.2% ± 23.4% and 40.9% ± 28.8%) (P > .05). There was a decrease in the percentage of type I fibers between children younger and older than 12 years (P < 0.05), although this was not due to OSA (P > 0.05).

CONCLUSIONS

There were no specific changes via adenosine triphosphatase staining or a difference in distribution of subtype fibers via quantitative real-time polymerase chain reaction between children with severe pediatric OSA and those with simple snoring, whereas the percentage of type I fiber decreased dynamically due to age but not OSA.

CLINICAL TRIAL REGISTRATION

Registry: Chinese Clinical Trials Registry; Name: A study of the mechanism of the conversion of upper airway expasion muscle's fiver types of OSA patient which may be mediated by estrogen-related receptor alpha; URL: https://www.chictr.org.cn/showproj.aspx?proj=6144; Identifier: ChiCTR-CCC-13003415.

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.

Obstruction level associated with outcome in hypoglossal nerve stimulation

Purpose

Selective hypoglossal nerve stimulation (sHNS) constitutes an effective surgical alternative for patients with obstructive sleep apnea (OSA). sHNS results in tongue protrusion and consecutive alleviation of obstructions at the tongue base level (lower obstructions). Furthermore, obstructions at the soft palate level (upper obstructions) may be prevented through palatoglossal coupling as seen on sleep endoscopy. However, it has not been studied if the distribution of obstruction level during a whole night measurement is a relevant factor for the treatment outcome.

Methods

Obstruction levels were measured with a manometry system during a whole night of sleep in 26 patients with OSA (f = 1, m = 25; age 59.4 ± 11.3; BMI = 29.6 ± 3.6) either before (n = 9) or after sHNS implantation (n = 12). Five patients received a measurement before and after implantation. Obstructions were categorized into velar (soft palate and above), infravelar (below soft palate), and multilevel obstructions. An association between obstruction level and treatment outcome was calculated.

Results

The mean distribution of preoperative obstruction level could be divided into the following: 38% velar, 46% multilevel, and 16% infravelar obstructions. Patients with a good treatment response (defined as AHI < 15/h and AHI reduction of 50%) had fewer preoperative velar obstructions compared to non-responder (17% vs. 54%, p-value = 0.006). In patients measured after sHNS implantation, a significantly higher rate of multilevel obstructions per hour was measured in non-responders (p-value = 0.012).

Conclusions

Selective hypoglossal nerve stimulation was more effective in patients with fewer obstructions at the soft palate level. Manometry may be a complementary diagnostic procedure for the selection of patients for HNS.

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.

Critical Review and Consensus Statement for Neural Monitoring in Otolaryngologic Head, Neck, and Endocrine Surgery

BACKGROUND

Enhancing patient outcomes in an array of surgical procedures in the head and neck requires the maintenance of complex regional functions through the protection of cranial nerve integrity. This review and consensus statement cover the scope of cranial nerve monitoring of all cranial nerves that are of practical importance in head, neck, and endocrine surgery except for cranial nerves VII and VIII within the temporal bone. Complete and applied understanding of neurophysiologic principles facilitates the surgeon's ability to monitor the at-risk nerve.

METHODS

The American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) identified the need for a consensus statement on cranial nerve monitoring. An AAO-HNS task force was created through soliciting experts on the subject. Relevant domains were identified, including residency education, neurophysiology, application, and various techniques for monitoring pertinent cranial nerves. A document was generated to incorporate and consolidate these domains. The panel used a modified Delphi method for consensus generation.

RESULTS

Consensus was achieved in the domains of education needs and anesthesia considerations, as well as setup, troubleshooting, and documentation. Specific cranial nerve monitoring was evaluated and reached consensus for all cranial nerves in statement 4 with the exception of the spinal accessory nerve. Although the spinal accessory nerve's value can never be marginalized, the task force did not feel that the existing literature was as robust to support a recommendation of routine monitoring of this nerve. In contrast, there is robust supporting literature cited and consensus for routine monitoring in certain procedures, such as thyroid surgery, to optimize patient outcomes.

CONCLUSIONS

The AAO-HNS Cranial Nerve Monitoring Task Force has provided a state-of-the-art review in neural monitoring in otolaryngologic head, neck, and endocrine surgery. The evidence-based review was complemented by consensus statements utilizing a modified Delphi method to prioritize key statements to enhance patient outcomes in an array of surgical procedures in the head and neck. A precise definition of what actually constitutes intraoperative nerve monitoring and its benefits have been provided.

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.

Long-term changes of stimulation intensities in hypoglossal nerve stimulation

STUDY OBJECTIVES

Hypoglossal nerve stimulation (HNS) is a novel therapy in the treatment of obstructive sleep apnea. Previous studies have focused on the effectiveness of HNS, but there are no studies specifically investigating the long-term changes of the stimulation intensities in HNS. Increasing stimulation intensity requirements have been reported in the past in other peripheral nerve stimulation therapies. The aim of this study was to investigate the development of stimulation intensities over the observation period of 4 years.

METHODS

All patients who were implanted with an HNS system since December 2013 and maintained a bipolar configuration over the observation period were included. Sensation threshold (ST), functional threshold, the titrated stimulation intensity (SI), and the apnea-hypopnea index (AHI) were recorded.

RESULTS

A total of 82 patients were enrolled (sex: 69 men, 13 women, age: 60 ± 11 years, body mass index: 29. 8 ± 4.0 kg/m²). Two months after surgery, the median ST was 0.8 ± 0.5 V. During the observation period of 48 months, no significant change of ST was observed. The median ST was 1.0 ± 0.4 V (P = 0.93) at 48 months. Similar results were found for functional threshold and the titrated stimulation intensity. There was a significant reduction of the baseline median AHI when compared with the median AHI at 1, 12, 24, 36 and 48 months after surgery (P < 0.05).

CONCLUSIONS

The stimulation intensities in HNS show no significant changes over 4 years. Despite the constant stimulation intensity, AHI was significantly reduced. This indicates that the stimulation threshold of the hypoglossal nerve does not change over time with this therapy.

The practicality of a two-incision surgical approach for hypoglossal nerve stimulator implantation

INTRODUCTION

Determine the feasibility of a two-incision surgical approach to hypoglossal nerve stimulator implantation based on anatomic considerations.

METHODS

Upper airway stimulation (UAS) using the Inspire system uses three implanted devices-the implantable pulse generator (IPG), stimulation lead and sensing chest wall lead. The traditional surgical approach requires three skin incisions located on the submandibular neck, anterosuperior chest wall and inferolateral chest wall. Our surgical team sought to determine the anatomic considerations of combining the two chest wall incisions into one. In order to minimize morbidity and reduce operative time, the chest wall sensing lead was placed posterolateral to the IPG site via the same incision.

RESULTS

Using an adult cadaver for anatomical analysis, access to the third and fourth intercostal spaces was made more difficult by the pectoralis major humeral head and upper arm. The intercostal space was narrower, the musculature along the anterior axillary line and anterior chest wall was devoid of the innermost intercostal muscle group found more laterally. Furthermore, there were much thinner external and internal intercostal muscle components as they transitioned to a membranous layer anteriorly in comparison to the inferolateral chest wall.

CONCLUSION

Lack of the innermost intercostal muscle and thinning of the external and internal intercostal muscles lateral to the IPG site leaves little barrier between the thoracic musculature and parietal pleural increasing the risk of complications such as pleurisy and pneumothorax. Given the anatomical findings, a two-incision surgical approach for UAS therapy is at higher risk for complications.

Prospective Determination of Airway Response to Upper Airway Stimulation: A New Opportunity for Advanced Device Titration

OBJECTIVES/HYPOTHESIS

Response to upper airway stimulation (UAS) is associated with the degree of airway opening during stimulation. UAS programming may affect this opening. The objective of this study was to examine airway changes in response to five different electrode configurations programmable within the Inspire UAS system.

STUDY DESIGN

Prospective single-arm cohort study.

METHODS

Subjects who underwent UAS implantation were recruited for a prospective single-arm cohort study during UAS device activation. Functional thresholds were recorded for all settings. Awake nasopharyngoscopy was performed to examine the retropalatal (RP) and retroglossal (RG) regions at rest and during activation with all settings at their functional thresholds. Cross-sectional measurements were made by two blinded reviewers and reported as percent change in airway size.

RESULTS

Sixteen patients were included. The standard setting (+-+) resulted in the greatest change in RP area in 43.8% of patients. An alternative setting resulted in greatest change in 56.2% of patients (--- and o-o in 18.8% each, -o- in 12.5%, and -+- in 6.3% of patients). Average response to all five settings was utilized to classify degree of palatoglossal coupling. Most patients had some enlargement (20%-70% change in RP area, 43.8%) or no enlargement (<20% change, 43.8%), whereas a minority of patients (12.5%) had marked enlargement (>70% change). RP and RG expansion were not correlated.

CONCLUSION

Degree of RP expansion varied among patients and settings. Although the standard setting resulted in greatest RP change in a plurality of patients, over half had a greater response to an alternative setting. Future studies should address whether choice of setting based on RP expansion results in improved outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:218-223, 2021.

Cross motor innervation of the hypoglossal nerve-a pilot study of predictors for successful opening of the soft palate

PURPOSE

Selective hypoglossal nerve stimulation has proven to be a successful treatment option in patients with obstructive sleep apnea. The aim of this pilot study was to investigate if there is a cross-innervation of the hypoglossal nerve in humans and if patients with this phenotype show a different response to hypoglossal nerve stimulation compared to those with ipsilateral-only innervation METHODS: Nineteen patients who previously received a selective hypoglossal nerve stimulation system (Inspire Medical Systems, Golden Valley, USA) were implanted with a nerve integrity system placing electrodes on both sides of the tongue. Tongue motions were recorded one and two months after surgery from transoral and transnasal views. Polysomnography (PSG) was also performed at two months. Electromyogram (EMG) signals and tongue motions after activation were compared with PSG findings.

RESULTS

Cross-innervation showed significant correlation with bilateral tongue movement and bilateral tongue base opening, which were associated with better PSG outcomes.

CONCLUSION

Cross motor innervation of the hypoglossal nerve occurs in approximately 50% of humans, which is associated with a positive effect on PSG outcomes. Bilateral stimulation of the hypoglossal nerve may be a solution for non-responding patients with pronounced collapse at the soft palate during drug-induced sleep endoscopy.

Contralateral Tongue Muscle Activation during Hypoglossal Nerve Stimulation

OBJECTIVE

The effectiveness of upper airway stimulation via hypoglossal nerve stimulation for obstructive sleep apnea depends upon the pattern of tongue muscle activation produced. This study investigated the nature of contralateral tongue muscle activation by unilateral hypoglossal nerve stimulation using intraoperative nerve integrity monitoring in conjunction with electromyography and explored the relationship between contralateral tongue muscle activation and polysomnographic measures of obstructive sleep apnea severity.

STUDY DESIGN

Prospective case series.

SETTING

Tertiary care medical center.

SUBJECTS AND METHODS

Fifty-one patients underwent unilateral (right) hypoglossal nerve stimulator implantation for obstructive sleep apnea. Neurophysiological data included electromyographic responses in ipsilateral (right) and contralateral (left) genioglossus muscles in response to intraoperative bipolar probe stimulation (0.3 mA) of medial hypoglossal nerve branches. Clinical data included pre- and postoperative apnea-hypopnea indices and oxygen desaturation levels.

RESULTS

A subset of patients (20/51, 39%) exhibited electromyographic responses in both the ipsilateral and contralateral genioglossus (bilateral), whereas the remaining patients (31/51, 61%) exhibited electromyographic responses only in the ipsilateral genioglossus (unilateral). The baseline characteristics of bilateral and unilateral responders were similar. Both groups exhibited significant and comparable improvements in apnea-hypopnea index and oxygen desaturations after hypoglossal nerve stimulation. Neither the amplitude nor the latency of contralateral genioglossus responses was predictive of clinical outcomes.

CONCLUSION

A subset of patients undergoing unilateral hypoglossal nerve stimulation exhibits activation of contralateral genioglossus muscles. Patients with unilateral and bilateral genioglossus responses exhibit comparable, robust improvements in apnea-hypopnea index and oxygen desaturation levels.

Base of Tongue Surgery for Obstructive Sleep Apnea in the Era of Neurostimulation

Retroglossal collapse is commonly seen in patients with obstructive sleep apnea. The role of upper airway stimulation surgery for these patients continues to evolve. However, base of tongue reduction surgery continues to have usefulness for appropriately selected patients with obstructive sleep apnea. Specific tongue base approaches may vary in response to patient and surgeon preferences and be used in multilevel surgery where appropriate. Key factors include patient age, willingness to undergo device implantation, and preferences for outpatient versus inpatient procedure, single procedure versus multiple, and tolerance for various procedure-specific postoperative restrictions and potential complications.

Implantable Neurostimulation for Treatment of Sleep Apnea: Present and Future

Hypoglossal nerve stimulation (HNS) therapy represents a novel approach and a paradigm shift in the evolution of obstructive sleep apnea (OSA) treatment as a hybrid surgically implanted, medically titratable device. Unlike traditional sleep apnea surgical procedures, HNS augments the neuromuscular activity of the pharynx, preserves upper airway structure and function, and has the potential to provide multilevel upper airway improvement with one procedure. The early success of HNS sets the stage for new technology development, further investigation into optimal patient selection and therapy titration, and application to other subsets of the OSA population.

Upper airway stimulation for obstructive sleep apnea-Can radiological position monitoring predict tongue motion one year after implantation?

BACKGROUND

Tongue motion patterns (TMP) can influence the outcome of upper airway stimulation (UAS) in the treatment of obstructive sleep apnea (OSA). As a postoperative control, the cuff position of the stimulation lead is monitored via X‑ray imaging. A multidimensional X‑ray assessment system was established and the association between these positional assessments and TMP was investigated 1 year after implantation.

MATERIAL AND METHODS

The study on TMP and the X‑ray assessments were carried out at a German ear nose and throat clinic as an implantation center. The TMPs were assessed under bipolar electrode configuration and were categorized according to the currently available literature as right-sided protrusion (RP), left-sided protrusion (LP), bilateral protrusion (BP) and mixed activation (MA). The X‑ray assessment was carried out in five dimensions: the position relative to the mandible and hyoid, cuff steepness in the lateral view of the neck, the cuff position based on the single electrode, and the lead connection to the cuff in the anterior-posterior view. The analyses were performed by three raters with different medical backgrounds and knowledge regarding TMP.

RESULTS

In approximately 60% of patients, the apnea-hypopnea index was reduced to below 15/h 1 year after implantation. The most common TMPs were RP and BP (82.9%). The interrater variability of the X‑ray assessment was good except for one category. Furthermore, no relevant associations were found apart from the correlation between a favorable TMP and the cuff position with respect to the lateral position of the stimulation cable.

CONCLUSION

Despite good interrater variability and convenient usage of the suggested X‑ray assessment system, this approach did not enable the identification of any associations by which a TM and, therefore, a possible straightforward or complicated treatment pathway could be predicted. Attention should possibly be paid to a rotation of the cuff during implantation with a lateral position of the stimulation lead.

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.

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.

Neurophysiological monitoring of tongue muscle activation during hypoglossal nerve stimulation

OBJECTIVES/HYPOTHESIS

Upper airway stimulation for obstructive sleep apnea (OSA) via implantable hypoglossal nerve stimulation (HGNS) reduces airway obstruction by selectively stimulating nerve fibers that innervate muscles that produce tongue protrusion, while avoiding fibers that produce tongue retraction. This selective stimulation likely depends upon the location, intensity, and type of electrical stimulation delivered. This study investigates the impact of changing stimulation parameters on tongue muscle activation during HGNS using intraoperative nerve integrity monitoring in conjunction with electromyography (EMG).

STUDY DESIGN

Prospective case series.

METHODS

Ten patients undergoing unilateral HGNS implantation for OSA in a university hospital setting were studied. Data included EMG responses in tongue muscles that produce protrusion (genioglossus), retraction (styloglossus/hyoglossus), and stiffening (transverse/vertical) in response to intraoperative bipolar probe electrical stimulation of lateral and medial branches of the hypoglossal nerve (HGN) and to implantable pulse generator (IPG) unipolar and bipolar settings after placement of the stimulation cuff.

RESULTS

Stimulation of medial division HGN branches resulted in EMG responses in genioglossus muscles, but not in styloglossus/hyoglossus muscles, whereas stimulation of the lateral division HGN branches drove responses in styloglossus/hyoglossus muscles. Variable responses in transverse/vertical muscles were observed with stimulation of lateral and medial division branches. After electrode cuff placement, unipolar and bipolar HGN stimulation configurations of IPG resulted in unique patterns of muscle activation.

CONCLUSIONS

The relative activation of extrinsic and intrinsic tongue musculature by HGNS is determined by stimulus location, intensity, and type. Intraoperative neurophysiological monitoring of tongue muscle activation enables proper electrode cuff placement and may provide essential data for stimulus optimization.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1836-1843, 2020.

[Upper Airway Stimulation for obstructive sleep apnea-Can radiological position monitoring predict tongue motion one year after implantation? German version]

BACKGROUND

Tongue motion patterns (TMP) can influence the outcome of upper airway stimulation (UAS) in the treatment of obstructive sleep apnea (OSA). As a postoperative control the cuff position of the stimulation lead is monitored via X‑ray imaging. A multidimensional X‑ray assessment system was established and the association between these positional assessments and TMP was investigated 1 year after implantation.

MATERIAL AND METHODS

The study on TMP and the X‑ray assessments were carried out at a German ear nose and throat clinic as an implantation center. The TMPs were assessed under bipolar electrode configuration and were categorized according to the currently available literature as right-sided protrusion (RP), left-sided protrusion (LP), bilateral protrusion (BP) and mixed activation (MA). The X‑ray assessment was carried out in five dimensions: the position relative to the mandible and hyoid, cuff steepness in the lateral view of the neck, the cuff position based on the single electrode and the lead connection to the cuff in the anterior-posterior view. The analyses were performed by three raters with different medical backgrounds and knowledge regarding TMP.

RESULTS

In approximately 60% of the patients the apnea-hypopnea index was reduced to below 15/h, 1 year after implantation. The most common TMPs were RP and BP (82.9%). The interrater variability of the X‑ray assessment was good except for one category. Furthermore, no relevant associations were found apart from the correlation between a favorable TMP and the cuff position with respect to the lateral position of the stimulation cable.

CONCLUSION

Despite good interrater variability and convenient usage of the suggested X‑ray assessment system, this approach did not enable the identification of any associations, by which a TM and therefore a possible straightforward or complicated treatment pathway could be predicted. Attention should possibly be paid to a rotation of the cuff during implantation with a lateral position of the stimulation lead.

Long-term follow-up of the German post-market study for upper airway stimulation for obstructive sleep apnea

PURPOSE

Upper airway stimulation (UAS) is an effective treatment for obstructive sleep apnea (OSA) in positive airway pressure (PAP) failure. Most reports have presented short-term data, so long-term safety and efficacy reports are rare. The German post-market study (G-PMS) has followed approximately 60 patients from three implanting centers for several years.

METHODS

Patients with OSA and PAP failure qualified for the G-PMS by the absence of obesity class 2 an AHI between 15 and 65 events/h and absence of complete concentric collapse at the velum during drug-induced sleep endoscopy. Optional 2- and 3-year follow-ups after implantation were collected during routine clinical practice. We measured respiratory parameters such as apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) and daytime sleepiness using the Epworth sleepiness scale (ESS) in a per protocol analysis. Usage was calculated from device-downloaded reports. Device-related complications were documented.

RESULTS

Of the 60 original patients, 41 returned for 2-year follow-up, and 38 for 3 years. About 76% at 2 years and 68% at 3 years met the criterion of therapy success defined as an AHI below 15/h. The median AHI was reduced from 28.6/h (baseline) to 9.0/h (2 years) and 10.0/h (3 years); whereas median ODI decreased from 27.0 to 6.3/h (2 years), and 8.3/h (3 years). Median ESS improved from baseline 13 points to 4 (2 years) and 6 (3 years). Usage was stable at approximately 45 h per week at 2 and 3 years. Serious device-related adverse events were rare, with two-device explantation between 12 to 36 months postoperatively.

CONCLUSIONS

The German multi-center long-term outcomes compare favorably with previously published studies. Respiratory and sleepiness efficacy outcomes were sustained over 2 and 3 years, with a favorable safety profile, supporting the safety and efficacy of a chronic implantable therapy.

Upper Airway Stimulation Response in Older Adults with Moderate to Severe Obstructive Sleep Apnea

OBJECTIVE

To evaluate the impact of age on safety, efficacy, and usage of upper airway stimulation (UAS).

STUDY DESIGN

Multicenter observational study.

SETTING

Thirteen US hospitals and 3 German hospitals.

SUBJECTS AND METHODS

The ADHERE registry is a multicenter database enrolling patients undergoing UAS implantation from October 2016 to April 2018. Outcome measures included the Epworth Sleepiness Scale, apnea-hypopnea index (AHI), therapy usage, and complications. Data were segmented by age (<65 vs ≥65 years).

RESULTS

Younger adults (n = 365) were a mean ± SD 52.7 ± 7.9 years old and 82% male, with a body mass index of 29.6 ± 3.8. Older adults (n = 235) were 71.1 ± 4.8 years old and 71% male, with a body mass index of 28.8 ± 3.8. Baseline AHI was similar (younger, 36.2 ± 15.9; older, 36.1 ± 14.8). Both groups had lower AHI at 12 months versus baseline (P < .001), but the older group showed a greater reduction (7.6 ± 6.9 vs 11.9 ± 13.4, P = .01). The Epworth Sleepiness Scale score decreased from 12.3 ± 5.4 to 7.1 ± 4.8 (P < .001) among younger adults and from 10.7 ± 5.7 to 6.3 ± 4.4 (P < .001) among older adults. Usage was slightly higher among older adults (6.0 ± 2.0 vs 5.4 ± 2.1 hours/night, P = .02). Surgical time was similar between younger patients (2.4 ± 0.7 hours) and older patients (2.3 ± 0.7 hours, P = .40), with comparably low complications.

CONCLUSION

AHI reduction and therapy usage were found to be somewhat higher among patients aged ≥65 years who were treated with UAS. Surgical complications were low, in contrast to traditional sleep surgery.

Upper airway stimulation therapy and sleep architecture in patients with obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

To quantify changes in sleep architecture before and after upper airway stimulation (UAS) therapy in patients with obstructive sleep apnea.

STUDY DESIGN

Retrospective chart review.

METHODS

This study was performed at a single-institution tertiary academic care center. Patients who responded successfully to UAS implantation were selected for this study. Preoperative and postoperative sleep studies were compared to determine sleep architecture changes. Primary outcomes included sleep architecture parameters such as N1, N2, N3, and rapid eye movement (REM) in addition to others. Secondary outcomes included body mass index.

RESULTS

Thirty-five patients met inclusion criteria for this study. There was significant improvement across several sleep architecture parameters. N1 sleep percent decreased from 16.7% ± 2.1% preoperatively to 10.1% ± 1.6% postoperatively (P = .023). Time spent in N2 increased from 148.0 ± 12.4 minutes to 185.5 ± 10.4 minutes (P = .030), whereas N3 increased from 21.9 ± 5.0 minutes to 57.0 ± 11.1 minutes (P = .013). No significant changes were observed in REM sleep. Arousal index decreased from 38.8 ± 4.0 to 30.3 ± 4.0 (P = .050).

CONCLUSIONS

There was significant improvement across several sleep architecture parameters among patients who responded successfully to UAS implantation.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1085-1089, 2020.

Domiciliary use of transcutaneous electrical stimulation for patients with obstructive sleep apnoea: a conceptual framework for the TESLA home programme

Obstructive sleep apnoea (OSA) is a global health problem of increasing prevalence. Effective treatments are available with continuous positive airway pressure (CPAP) therapy and mandibular advancement devices (MAD). However, there is limited long-term adherence to therapy, as CPAP and MAD require permanent usage to avoid recurrence of the symptoms and adverse ill health. Alternative treatments would aid in the treatment cascade to manage OSA effectively whenever standard therapy has been trialled and failed. Hypoglossal nerve stimulation (HNS), an invasive approach to stimulate the pharyngeal dilator muscles of the upper airway during sleep, has been approved for the treatment of OSA by several healthcare systems in recent years. In parallel to the development of HNS, a non-invasive approach has been developed to deliver electrical stimulation. Transcutaneous electrical stimulation in obstructive sleep apnoea (TESLA) uses non-invasive electrical stimulation to increase neuromuscular tone of the upper airway dilator muscles of patients with OSA during sleep. Data from previous feasibility studies and randomised controlled trials have helped to identify a subgroup of patients who are "responders" to this treatment. However, further investigations are required to assess usability, functionality and task accomplishment of this novel treatment. Consideration of these factors in the study design of future clinical trials will strengthen research methodology and protocols, improve patient related outcome measures and assessments, to optimise this emerging therapeutical option. In this review, we will introduce a conceptual framework for the TESLA home programme highlighting qualitative aspects and outcomes.

Outcomes of Hypoglossal Nerve Upper Airway Stimulation among Patients with Isolated Retropalatal Collapse

Objective

To examine whether patients with isolated retropalatal collapse perform as well as others following implantation with an upper airway stimulation (UAS) device.

Study Design

Retrospective review.

Setting

Single-institution tertiary academic care medical center.

Subjects and Methods

Following drug-induced sleep endoscopy, subjects who met inclusion criteria for implantation with a UAS device received an implant per industry standard. Subjects with isolated retropalatal collapse were compared with those having other patterns of collapse. Outcome measures included apnea-hypopnea index (AHI) and nadir oxyhemoglobin saturation (NOS).

Results

Ninety-one patients were implanted during the duration of the study, and 82 met inclusion criteria for analysis. Twenty-five had isolated retropalatal collapse, while the remaining 57 had other patterns of collapse on drug-induced sleep endoscopy. For all patients, mean preoperative AHI and NOS were 38.7 (95% CI, 35.0-42.4) and 78% (95% CI, 75%-80%), respectively; these improved postoperatively to 4.5 (95% CI, 2.3-6.6) and 91% (95% CI, 91%-92%). There was no significant preoperative difference between groups with regard to demographics, AHI, or NOS. Group comparison showed postoperative AHI to be 5.7 (95% CI, 0.57-10.8) for patients with isolated retropalatal collapse and 3.9 (95% CI, 1.7-6.1) for other patients ( P = .888). Postoperative NOS was 92% (95% CI, 90%-94%) among patients with isolated retropalatal collapse and 91% (95% CI, 90%-92%) for others ( P = .402).

Conclusions

All patients showed significant improvement following implantation with UAS. Patients with isolated retropalatal collapse showed similar improvement to other types of collapse with regard to AHI and NOS.