Effect of upper-airway stimulation for obstructive sleep apnoea on airway dimensions

Success of Hypoglossal Nerve Stimulation Using Mandibular Advancement During Sleep Endoscopy

OBJECTIVES/HYPOTHESIS

Hypoglossal nerve stimulation (HGNS) effectively treats obstructive sleep apnea in select patients. Drug-induced sleep endoscopy (DISE) is required for HGNS candidacy. Data suggest that mandibular advancement (MA) devices and HGNS share similar target populations. We aimed to test the association between MA's effect on the velum and lateral walls during DISE in relation to the improvement in the apnea-hypopnea index (AHI) with HGNS.

STUDY DESIGN

Prospective case series METHODS: All patients completed preoperative polysomnography or home sleep study, DISE with MA prior to HGNS implantation, and full-night efficacy sleep tests. Adult patients with body mass index (BMI) ≤ 35 and AHI ≥ 15 were included. Two independent reviewers scored DISE videos.

RESULTS

Forty-six patients were included from October 2015 to January 2019. Mean BMI (standard deviation) was 28.5 (3.7) kg/m² . Patients with a reduced airway response to MA had greater AHI improvement than patients with a robust response (21.7, 95% confidence interval [CI]: 14.4 to 29.0 vs. 4.9, 95% CI: -8.9 to 18.6; P = .03). Patients with complete baseline collapse at the velum and lateral walls (n = 11) had less response compared to those with partial collapse (n = 35) (AHI reduction of 4.4 [95% CI: -8.6 to 17.4] vs. 22.3 [95% CI: 15.1 to 29.6; P = .02]).

CONCLUSIONS

Patients having significant airway improvement in the upper pharynx with MA during DISE appear less likely to succeed with HGNS. This phenomenon might be secondary to the worsened baseline obstruction of the upper pharynx in such patients.

LEVEL OF EVIDENCE

4 Laryngoscope, 2020.

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.

Genioglossus muscle responses to resistive loads in severe OSA patients and healthy control subjects

This study aimed to determine whether there is impairment of genioglossus neuromuscular responses to small negative pressure respiratory stimuli, close to the conscious detection threshold, in obstructive sleep apnea (OSA). We compared genioglossus electromyogram (EMGgg) responses to midinspiratory resistive loads of varying intensity (≈1.2-6.2 cmH₂O·L^-1·s), delivered via a nasal mask, between 16 severe OSA and 17 control participants while the subjects were awake and in a seated upright position. We examined the relationship between stimulus intensity and peak EMGgg amplitude in a 200-ms poststimulus window and hypothesized that OSA patients would have an increased activation threshold and reduced sensitivity in the relationship between EMGgg activation and stimulus intensity. There was no significant difference between control and OSA participants in the threshold (P = 0.545) or the sensitivity (P = 0.482) of the EMGgg amplitude vs. stimulus intensity relationship, where change in epiglottic pressure relative to background epiglottic pressure represented stimulus intensity. These results do not support the hypothesis that deficits in neuromuscular response to negative upper airway pressure exist in OSA during wakefulness; however, the results are likely influenced by a counterintuitive and novel genioglossus muscle suppression response observed in a significant proportion of both OSA and healthy control participants. This suppression response may relate to the inhibition seen in inspiratory muscles such as the diaphragm in response to sudden-onset negative pressure, and its presence provides new insight into the upper airway neuromuscular response to the collapsing force of negative pressure.NEW & NOTEWORTHY Our study used a novel midinspiratory resistive load stimulus to study upper airway neuromuscular responses to negative pressure during wakefulness in obstructive sleep apnea (OSA). Although no differences were found between OSA and healthy groups, the study uncovered a novel and unexpected suppression of neuromuscular activity in a large proportion of both OSA and healthy participants. The unusual response provides new insight into the upper airway neuromuscular response to the collapsing force of negative pressure.

[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.

Obstructive Sleep Apnea: Emerging Treatments Targeting the Genioglossus Muscle

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway obstruction caused by a loss of upper airway dilator muscle tone during sleep and an inadequate compensatory response by these muscles in the context of an anatomically compromised airway. The genioglossus (GG) is the main upper airway dilator muscle. Currently, continuous positive airway pressure is the first-line treatment for OSA. Nevertheless, problems related to poor adherence have been described in some groups of patients. In recent years, new OSA treatment strategies have been developed to improve GG function. (A) Hypoglossal nerve electrical stimulation leads to significant improvements in objective (apnea-hypopnea index, or AHI) and subjective measurements of OSA severity, but its invasive nature limits its application. (B) A recently introduced combination of drugs administered orally before bedtime reduces AHI and improves the responsiveness of the GG. (C) Finally, myofunctional therapy also decreases AHI, and it might be considered in combination with other treatments. Our objective is to review these therapies in order to advance current understanding of the prospects for alternative OSA treatments.

Previous Surgery and Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea

Objective

To examine whether previous palate or hypopharyngeal surgery was associated with efficacy of treatment of obstructive sleep apnea with hypoglossal nerve stimulation.

Study Design

Cohort (retrospective and prospective).

Setting

Eleven academic medical centers.

Subjects and Methods

Adults treated with hypoglossal nerve stimulation were enrolled in the ADHERE Registry. Outcomes were defined by the apnea-hypopnea index (AHI), in 3 ways: change in the AHI and 2 definitions of therapy response requiring ≥50% reduction in the AHI to a level <20 events/h (Response20) or 15 events/h (Response15). Previous palate and hypopharyngeal (tongue, epiglottis, or maxillofacial) procedures were documented. Linear and logistic regression examined the association between previous palate or hypopharyngeal surgery and outcomes, with adjustment for age, sex, and body mass index.

Results

The majority (73%, 217 of 299) had no previous palate or hypopharyngeal surgery, while 25% and 9% had previous palate or hypopharyngeal surgery, respectively, including 6% with previous palate and hypopharyngeal surgery. Baseline AHI (36.0 ± 15.6 events/h) decreased to 12.0 ± 13.3 at therapy titration ( P < .001) and 11.4 ± 12.6 at final follow-up ( P < .001). Any previous surgery, previous palate surgery, and previous hypopharyngeal surgery were not clearly associated with treatment response; for example, any previous surgery was associated with a 0.69 (95% CI: 0.37, 1.27) odds of response (Response20 measure) at therapy titration and a 0.55 (95% CI: 0.22, 1.34) odds of response (Response20 measure) at final follow-up.

Conclusion

Previous upper airway surgery was not clearly associated with efficacy of hypoglossal nerve stimulation.

[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.

Anatomic predictors of response and mechanism of action of upper airway stimulation therapy in patients with obstructive sleep apnea

Study Objectives

Upper airway stimulation has been shown to be an effective treatment for some patients with obstructive sleep apnea. However, the mechanism by which hypoglossal nerve stimulation increases upper airway caliber is not clear. Therefore, the objective of this study was to identify the mechanism of action of upper airway stimulation. We hypothesized that, with upper airway stimulation, responders would show greater airway opening in the retroglossal (base of the tongue) region, greater hyoid movement toward the mandible, and greater anterior motion in the posterior, inferior region of the tongue compared with nonresponders.

Methods

Seven participants with obstructive sleep apnea who had been successfully treated with upper airway stimulation (responders) and six participants who were not successfully treated (nonresponders) underwent computed tomography imaging during wakefulness with and without hypoglossal nerve stimulation. Responders reduced their apnea-hypopnea index (AHI) by 22.63 ± 6.54 events per hour, whereas nonresponders had no change in their AHI (0.17 ± 14.04 events per hour). We examined differences in upper airway caliber, the volume of the upper airway soft tissue structures, craniofacial relationships, and centroid tongue and soft palate movement between responders and nonresponders with and without hypoglossal nerve stimulation.

Results

Our data indicate that compared with nonresponders, responders had a smaller baseline soft palate volume and, with stimulation, had (1) a greater increase in retroglossal airway size; (2) increased shortening of the mandible-hyoid distance; and (3) greater anterior displacement of the tongue.

Conclusions

These results suggest that smaller soft palate volumes at baseline and greater tongue movement anteriorly with stimulation improve the response to upper airway stimulation.

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.

Drug-Induced Sleep Endoscopy and Surgical Outcomes: A Multicenter Cohort Study

OBJECTIVE

To evaluate the association between findings of blinded reviews of preoperative drug-induced sleep endoscopy (DISE) examinations using the VOTE Classification and obstructive sleep apnea (OSA) surgical outcomes in a large multicenter, international cohort.

METHODS

Retrospective, multi-center cohort study of adults without tonsillar hypertrophy who underwent pharyngeal surgery for OSA. The study included only participants without enlarged tonsils. Four independent reviewers performed blinded review of preoperative DISE videos using the VOTE Classification system and scoring of a primary structure contributing to airway obstruction. DISE findings were examined for an association with surgical outcomes with univariate analyses and multiple regression.

RESULTS

Two hundred seventy-five study participants were included from 14 centers. Mean age was 51.4 ± 11.8 years, and body mass index was 30.1 ± 5.2 kg/m² . There was moderate interrater reliability (kappa = 0.40-0.60) for DISE findings. Oropharyngeal lateral wall-related obstruction was associated with poorer surgical outcomes (adjusted odds ratio (AOR) 0.51; 95% CI 0.27, 0.93). Complete tongue-related obstruction was associated with a lower odds of surgical response in moderate to severe OSA (AOR 0.52; 95% CI 0.28, 0.98), with findings that were similar but not statistically significant in other analyses. Surgical outcomes were not clearly associated with the degree and configuration of velum-related obstruction or the degree of epiglottis-related obstruction. Surgical response was associated with tonsil size and body mass index (inversely).

CONCLUSION

DISE findings concerning the oropharyngeal lateral walls and tongue may be the most important findings of this evaluation technique.

LEVEL OF EVIDENCE

2B Laryngoscope, 129:761-770, 2019.

Successful upper airway stimulation therapy in an adult Down syndrome patient with severe obstructive sleep apnea

PURPOSE

The aim of this study was to report on the successful application of upper airway stimulation (UAS) therapy in an adult Down syndrome (DS) patient with severe obstructive sleep apnea (OSA) and continuous positive airway pressure (CPAP) intolerance.

METHODS

Baseline polysomnography (PSG) in a 23-year-old male OSA patient (body mass index (BMI) 24.4 kg/m²) revealed an apnea/hypopnea index (AHI) of 61.5 events/h and oxygen desaturation index (ODI) of 39.7 events/h. Based on the clinical examination, PSG and drug-induced sleep endoscopy, the patient fulfilled the formal inclusion criteria for UAS therapy: AHI between 15 and 65 events/h, BMI < 32 kg/m², and no complete concentric collapse at the level of the velopharynx.

RESULTS

Implantation of the hypoglossal nerve stimulator in the adult patient with DS resulted in a substantial subjective as well as objective improvement of OSA (63 to 81% decrease in AHI and 77% decrease in ODI), translating into an overall satisfactory outcome.

CONCLUSION

Research on the long-term effectiveness of UAS therapy in a larger group of patients with DS is needed. However, based on the available literature and our presented case, respiration-synchronized electrostimulation of the hypoglossal nerve using UAS therapy may have a potential value in well-selected OSA patients with DS who are non-compliant to CPAP therapy.

Neurostimulation Treatment of OSA

Over the past 30 years, hypoglossal nerve stimulation has moved through a development pathway to become a viable treatment modality for patients with OSA. Initial pilot studies in animals and humans laid the conceptual foundation for this approach, leading to the development of fully implantable stimulating systems for therapeutic purposes. These devices were then shown to be both safe and efficacious in feasibility studies. One such closed-loop stimulating device was found to be effective in treating a limited spectrum of apneic patients and is currently approved by the US Food and Drug Administration for this purpose. Another open-loop stimulating system is currently being rigorously tested in a pivotal trial. Collectively, clinical trials of hypoglossal nerve stimulating systems have yielded important insights that can help optimize therapeutic responses to hypoglossal nerve stimulation. These insights include specific patient selection criteria and methods for delivering stimulation to specific portions of the hypoglossal nerve and/or genioglossus muscle. New approaches for activating efferent and afferent motor pathways are currently in early-stage laboratory development and hold some long-term promise as a novel therapy.

Sciatic nerve stimulation and its effects on upper airway resistance in the anesthetized rabbit model relevant to sleep apnea

Obstructive sleep apnea (OSA) is a disorder characterized by collapse of the velopharynx and/or oropharynx during sleep when drive to the upper airway is reduced. Here, we explore an indirect approach for activation of upper airway muscles that might affect airway dynamics, namely, unilateral electrical stimulation of the afferent fibers of the sciatic nerve, in an anesthetized rabbit model. A nerve cuff electrode was placed around the sciatic and hypoglossal nerves to deliver stimulus while airflow, air pressure, and alae nasi electromyogram (EMG) were monitored both before and after sciatic transection. Sciatic nerve stimulation increased respiratory effort, rate, and alae nasi EMG, which persisted for seconds after stimulation; however, upper airway resistance was unchanged. Hypoglossal stimulation reduced resistance without altering drive. Although sciatic nerve stimulation is not ideal for treating OSA, it remains a target for altering respiratory drive. NEW & NOTEWORTHY Previously, sciatic nerve stimulation has been shown to activate upper airway and chest wall muscles. The supposition that resistance through the upper airway would be reduced with this afferent reflex was disproven. Findings were in contrast with the effect of hypoglossal nerve stimulation, which was shown to decrease resistance without changing muscle activation or ventilatory drive.

Hypoglossal Nerve Stimulator Implantation in a Non-Academic Setting: Two-Year Result

Objectives/Hypothesis

Upper Airway Stimulation (UAS) is an FDA approved treatment option for patients with moderate-to-severe obstructive sleep apnea (OSA) who could not adhere to continuous positive airway pressure (CPAP). Previous studies have shown UAS reduced apnea-hypopnea index (AHI) in controlled clinical trials and from academic institutions. We report patient outcomes and therapy adherence of UAS in a non-academic hospital and clinic setting.

Study Design

Case series of consecutive patients.

Methods

Consecutive implants completed at a community hospital between January 2015 to Feb 2017 are included in this report. All patients underwent baseline polysomnography (PSG) recording and drug-induced sleep endoscopy (DISE) prior to the implant. All patients had returned for standard post-implantation titration PSG at a community sleep clinic to validate and adjust the stimulation setting for optimal response. Results were in mean ± SD, and pre- and post-implant data were compared using a paired student t-test.

Results

A total 22 patients undergoing UAS implant were overweight (BMI of 28.9 ± 5.0 kg/m2) and middle aged (63.2 ± 11.1 years), and had severe OSA (AHI of 35.9 ± 19.1). The AHI from the entire night of the titration study was 16.0 ± 10.4 (P < .01, compared with baseline), and the treatment AHI from the sleep period when the optimal setting was programmed was 1.2 ± 1.1 (P < .001, compared with baseline), and 90% patients had titrated AHI less than 5. The lowest SpO2 increased from 81% ± 8% at baseline to 91% ± 3% at the titrated setting (P = .001). After an average follow up of 95 ± 28.5 days, the therapy use per night was 7.0 ± 1.9 hours per night. The average postoperative ESS was 6.7 ± 5.3 of 18 patients, a reduction from the baseline of 10.9 ± 4.8. A total of 13 of 18 patients with postoperative ESS < 10, a measure indicated normalization of daytime sleepiness.

Conclusion

Patients who elected to receive UAS implant surgery at a non-academic hospital and followed at a sleep clinic showed significant reduction in OSA severity with strong adherence to treatment. These results supported that UAS as a valid treatment option for OSA can be successfully implemented in the non-academic hospital and clinic settings.

Level of Evidence

4.

Sleep-Disordered Breathing

PURPOSE OF REVIEW

Sleep-disordered breathing encompasses a broad spectrum of sleep-related breathing disorders, including obstructive sleep apnea (OSA), central sleep apnea, as well as sleep-related hypoventilation and hypoxemia. Diagnostic criteria have been updated in the International Classification of Sleep Disorders, Third Edition and the American Academy of Sleep Medicine Manual for Scoring Sleep and Associated Events. Neurologic providers should have basic knowledge and skills to identify at-risk patients, as these disorders are associated with substantial morbidity, the treatment of which is largely reversible.

RECENT FINDINGS

OSA is the most common form of sleep-disordered breathing and is highly prevalent and grossly underdiagnosed. Recent studies suggest that prevalence rates in patients with neurologic disorders including epilepsy and stroke exceed general population estimates. The physiologic changes that occur in OSA are vast and involve complex mechanisms that play a role in the pathogenesis of cardiovascular and metabolic disorders and, although largely unproven, likely impact brain health and disease progression in neurologic patients. A tailored sleep history and examination as well as validated screening instruments are effective in identifying patients with sleep-disordered breathing, although sleep testing is necessary for diagnostic confirmation. While continuous positive airway pressure therapy and other forms of noninvasive positive pressure ventilation remain gold standard treatments, newer therapies, including mandibular advancement, oral appliance devices, and hypoglossal nerve stimulation, have become available. Emerging evidence of the beneficial effects of treatment of sleep-disordered breathing on neurologic outcomes underscores the importance of sleep education and awareness for neurologic providers.

SUMMARY

Sleep-disordered breathing is highly prevalent and grossly underrecognized. The adverse medical and psychosocial consequences of OSA and other sleep-related breathing disorders are considerable. The impact of sleep therapies on highly prevalent neurologic disorders associated with substantial morbidity and health care costs is becoming increasingly recognized.

Challenges and perspectives in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is a major challenge for physicians and healthcare systems throughout the world. The high prevalence and the impact on daily life of OSA oblige clinicians to offer effective and acceptable treatment options. However, recent evidence has raised questions about the benefits of positive airway pressure therapy in ameliorating comorbidities.

An international expert group considered the current state of knowledge based on the most relevant publications in the previous 5 years, discussed the current challenges in the field, and proposed topics for future research on epidemiology, phenotyping, underlying mechanisms, prognostic implications and optimal treatment of patients with OSA.

The group concluded that a revision to the diagnostic criteria for OSA is required to include factors that reflect different clinical and pathophysiological phenotypes and relevant comorbidities (e.g.nondipping nocturnal blood pressure). Furthermore, current severity thresholds require revision to reflect factors such as the disparity in the apnoea–hypopnoea index (AHI) between polysomnography and sleep studies that do not include sleep stage measurements, in addition to the poor correlation between AHI and daytime symptoms such as sleepiness. Management decisions should be linked to the underlying phenotype and consider outcomes beyond AHI.

Hypoglossal nerve stimulation for obstructive sleep apnoea in a patient with previous tongue laceration

Upper airway stimulation of the tongue using an implantable neurostimulator has recently been approved for select patients with moderate to severe obstructive sleep apnoea (OSA) and intolerance to continuous positive airway pressure therapy. Effective implantation depends on the integrity of the hypoglossal nerve as well as the tongue musculature, notably the genioglossus. Prior trauma to either of these structures may be viewed as a relative contraindication to implantation. We describe a case of successful right hypoglossal nerve implantation in a patient with a history of left cardiac pacemaker placement and severe left penetrating tongue trauma with decreased mobility from contracture and deviation mimicking a hypoglossal nerve palsy. Preoperative and postoperative apnoea-hypopnoea index values were 52/hour and 5/hour, respectively. Prior soft tissue trauma to the tongue may not necessarily preclude surgical candidacy for upper airway stimulation in patients with OSA.

Hypoglossal nerve stimulation in a pre-clinical anesthetized rabbit model relevant to OSA

We tested the functional effects of hypoglossal (CNXII) stimulation in the anesthetized rabbit before and after injections of saline into the tongue base to obstruct the airway. Data (n = 6) show little or no effect of CN XII trunk stimulation; however, medial branch stimulation (20-100 Hz; 50-500 μs pulse width, and incremental increases from 10 μA) reduced upper airway resistance. Medial branch stimulation was less effective in reducing resistance than anterior advancement of the hyoid. Endoscopic viewing (n-3) of the retropalate showed this region as the narrowest and dynamically changed by anterior hyoid displacement, with less evident effects than CNXII stimulation. We conclude that under these conditions CNXII medial branch stimulation reduces airway resistance, especially after induced obstruction.

Application of drug-induced sleep endoscopy in patients treated with upper airway stimulation therapy

Objective

To determine the level of agreement among experienced operators of candidacy for upper airway stimulation (UAS) based on evaluation of drug-induced sleep endoscopy (DISE).

Methods

The trial was designed as a single-blinded cross-sectional study. Four otolaryngologists with extensive DISE experience were given 63 video clips from the STAR trial video library. These videos were graded using the VOTE classification. Percentage agreement and Cohen’s κ (for inter-rater reliability) were calculated between pairs of reviewers, assessing palatal complete concentric collapse (CCC) and determining UAS eligibility. Subjects were also grouped based on collapse severity for each reviewer.

Results

The reviewers had excellent (approximately 90%) agreement on findings at the level of the soft palate and tongue base. The inter-rater reliability for palatal CCC ranged from moderate to substantial. The agreement on determining the criteria for UAS implantation ranged from poor to moderate. All 4 upper airway structures as classified by the criteria of the VOTE were graded by all the reviewers as contributing to obstruction in a majority of subjects who were performed via application of DISE.

Conclusion

Application of DISE remains a subjective examination, even among those experienced operators, therefore more studies need to be performed for evaluation of improvement in inter-rater reliability after implantation of training videos.

Hypoglossal nerve stimulation for treatment of obstructive sleep apnea (OSA): a primer for oral and maxillofacial surgeons

The prevalence of obstructive sleep apnea (OSA) is estimated to be 1–5% of the adult population world-wide, and in Korea, it is reported at 4.5% of men and 3.2% of women (Age 40 to 69 years old). Active treatment of OSA is associated with decrease in insulin resistance, cardiovascular disease, psychosocial problems, and mortality. Surgical treatment of OSA has evolved in the era of neuromodulation with the advent of hypoglossal nerve stimulation (HGNS). We share this review of HGNS with our maxillofacial surgical colleagues to expand the scope of surgical care for OSA.

Development of a Clinical Pathway and Technical Aspects of Upper Airway Stimulation Therapy for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common disease with high morbidity and related mortality. Narrowing and collapse of the pharyngeal airway during sleep characterize the disease, resulting in a decrease (hypopnea) or a complete cessation (apnea) of oronasal airflow. Upper airway stimulation (UAS), using electrical neurostimulation of the hypoglossal nerve (n. XII) synchronized with ventilation, is a novel, evolving treatment option. UAS was found to be an effective treatment in CPAP-intolerant patients. The treatment success is partly due to the strict selection of the patients, based on previous findings. Furthermore, post-operative follow-up is needed in order to maintain or improve treatment outcome. Therefore, a clinical pathway, which provides structure and standardization, is crucial. In this paper, the aim is to discuss the technical aspects of UAS therapy and to describe a clinical pathway to organize the care process of UAS for OSA in a structured and standardized way.

Treating OSA: Current and emerging therapies beyond CPAP

Continuous positive airway pressure (CPAP) is the standard treatment for moderate-to-severe obstructive sleep apnoea (OSA). However, adherence to CPAP is limited and non-CPAP therapies are frequently explored. Oral appliance (OA) therapy is currently widely used for the treatment of snoring, mild, moderate and severe OSA. The most commonly used and studied OA consists of a maxillary and mandibular splint which hold the lower jaw forward during sleep. The efficacy of OA is inferior to CPAP; however, the effectiveness as measured by sleepiness, quality of life, endothelial function and blood pressure is similar likely due to higher acceptance and subjective adherence. Upper airway stimulation augments neural drive by unilaterally stimulating the hypoglossal nerve. The Stimulation Therapy for Apnea Reduction (STAR) study enrolled 126 patients and demonstrated a 68% reduction in OSA severity. A high upfront cost and variable response are the main limitations. Oropharyngeal exercises consist of a set of isometric and isotonic exercises involving the tongue, soft palate and lateral pharyngeal wall. The collective reported trials (n = 120) showed that oropharyngeal exercises can ameliorate OSA and snoring (~30-40%). Nasal EPAP devices consist of disposable one-way resister valve. A systematic review (n = 345) showed that nasal EPAP reduced OSA severity by 53%. The Winx device consists of a mouthpiece placed inside the oral cavity that is connected by tubing to a console that generates negative pressure. Winx may provide successful therapy for ~30-40% of OSA patients. In conclusion, several non-CPAP therapies to treat OSA are currently available.

Updates of operative techniques for upper airway stimulation

Selective upper airway stimulation has been established as an additional treatment for obstructive sleep apnea (OSA). Essential for the treatment is the precise placement of the cuff electrode for select branches of the hypoglossal nerve, which innervate the protrusors and stiffeners of the tongue. A direct approach to the distal hypoglossal nerve has been established to achieve this goal. For surgeons, detailed knowledge of this anatomy is vital. Another decisive step is the placement of the sensing lead between the intercostal muscles. Also, the complexity of follow-up care postoperatively should be kept in mind. The aim of this article is to provide the latest knowledge on the neuroanatomy of the hypoglossal nerve and to give surgeons a step-by-step guide on the current operative technique. Laryngoscope, 126:S12-S16, 2016.

[Hypoglossal nerve stimulation in patients with CPAP failure : Evolution of an alternative treatment for patients with obstructive sleep apnea]

Obstructive sleep apnea (OSA) is a common disease in western industrialized countries with increasing prevalence. Gold standard of therapy is nocturnal positive pressure ventilation by continuous positive airway pressure (CPAP). Due to complications and side effects of ventilation, therapy adherence is limited. Recently an alternative surgical treatment has become available for these patients, which uses established techniques to stimulate the hypoglossus nerve to open the upper airway during sleep. The aim of this work is to provide an overview of the history and current state of scientific knowledge of this therapy in the treatment of OSA. Currently, two systems are available on the market: respiratory-driven hypoglossal nerve stimulation (Inspire Medical Systems) and continuous hypoglossal nerve stimulation (ImThera Medical). For respiratory-driven hypoglossal nerve stimulation, a solid body of evidence is available and the therapy has been investigated in numerous multicenter clinical studies with regard to safety and efficacy. Only a small number of publications is available for continuous hypoglossal nerve stimulation. At the end of the last century, promising clinical results were shown in the first patients treated with hypoglossal nerve stimulation. Consequent technological and scientific development of respiratory-driven hypoglossal nerve stimulation in recent years led to its implementation in today's clinical routine. This therapy significantly broadens the spectrum of therapies in the treatment of OSA, especially for patients with CPAP intolerance.

Insights since FDA Approval of Hypoglossal Nerve Stimulation for the Treatment of Obstructive Sleep Apnea

Purpose

The literature on hypoglossal nerve stimulation (HNS) for the treatment of moderate-to-severe obstructive sleep apnea (OSA) was reviewed from 2014, the time of FDA approval for the Inspire Systems device, to 2017 for themes that might be useful conceptually and practically in the consideration of this new non-anatomic surgical therapy.

Recent Findings

there are now further follow-up articles since the 12-month results for Apnea Reduction (STAR) trial of the Inspire device, and post-approval publications which report similar and/0r improved AHI outcomes. Other emerging themes include drug-induced sedation endoscopy (DISE) as a tool in assessment of eligibility and a more detailed understanding of mechanisms for an HNS effects.

Summary

The post-STAR literature provides guidelines for an integrated coordination of medicine and surgery to appropriately screen and manage patients.

Outcome after one year of upper airway stimulation for obstructive sleep apnea in a multicenter German post-market study

OBJECTIVE/HYPOTHESIS

Upper airway stimulation (UAS) of the hypoglossal nerve has been implemented in the routine clinical practice for patients with moderate-to-severe obstructive sleep apnea (OSA) who could not adhere to continuous positive airway pressure. This study reports objective and patient-reported outcome after 12 months of implantation.

STUDY DESIGN

Multicenter prospective single-arm study.

METHODS

Consecutive patients who received the UAS system (Inspire Medical Systems, Inc., Minneapolis, Minnesota, Maple Grove, MN, U.S.A.) were enrolled in three German centers. Key study exclusion criteria included body mass index > 35 kg/m² , apnea-hypopnea index (AHI) < 15 or > 65, or complete concentric collapse at the soft palate during sedated endoscopy. Data collection at 6- and 12-month visit include home sleep test and patient-reported outcome measures.

RESULTS

Among the total of 60 participants, the median AHI reduced from 28.6 to 9.5 from baseline to 12 months. Patient-reported outcome measured in Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire both improved significantly from baseline to 12 months. The average usage time was 39.1 ± 14.9 hours per week among all participants based on recordings by the implanted device. One patient requested a removal of the device for cosmetic and other personal reasons and was completed without sequelae.

CONCLUSION

This study supported that UAS is a safe and effective treatment option for patients with OSA in routine clinical practice.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:509-515, 2018.

[S2e-guideline: "ENT-specific therapy of obstructive sleep apnea in adults" short version : Sleep Medicine Task Force of the German Society for Otorhinolaryngology, Head and Neck Surgery]

The present S2e-guideline is an update of the former S2e-guideline "treatment of obstructive sleep apnea in adults". The update was performed on behalf of the German Society for Otorhinolaryngology, Head and Neck Surgery by its Sleep Medicine Task Force. The long version of the guideline is valid from 5.9.2015 to 5.9.2020 and has been available (guideline No. 017-069) since November 2015 on the official AWMF website.The subsequently presented short version of the guideline summarizes the essentials in a legible way. For further information, please refer to the long version.

Upper Airway Stimulation for Obstructive Sleep Apnea: Self-Reported Outcomes at 24 Months

OBJECTIVES

To evaluate the long-term (24-mo) effect of cranial nerve upper airway stimulation (UAS) therapy on patient-centered obstructive sleep apnea (OSA) outcome measures.

METHODS

Prospective, multicenter, cohort study of 126 patients with moderate to severe OSA who had difficulty adhering to positive pressure therapy and received the surgically implanted UAS system. Outcomes were measured at baseline and postoperatively at 12 mo and 24 mo, and included self- and bedpartner-report of snoring intensity, Epworth Sleepiness Scale (ESS), and Functional Outcomes of Sleep Questionnaire (FOSQ). Additional analysis included FOSQ subscales, FOSQ-10, and treatment effect size.

RESULTS

Significant improvement in mean FOSQ score was observed from baseline (14.3) to 12 mo (17.3), and the effect was maintained at 24 mo (17.2). Similar improvements and maintenance of effect were seen with all FOSQ subscales and FOSQ-10. Subjective daytime sleepiness, as measured by mean ESS, improved significantly from baseline (11.6) to 12 mo (7.0) and 24 mo (7.1). Self-reported snoring severity showed increased percentage of "no" or "soft" snoring from 22% at baseline to 88% at 12 mo and 91% at 24 mo. UAS demonstrated large effect size (> 0.8) at 12 and 24 mo for overall ESS and FOSQ measures, and the effect size compared favorably to previously published effect size with other sleep apnea treatments.

CONCLUSIONS

In a selected group of patients with moderate to severe OSA and body mass index ≤ 32 kg/m2, hypoglossal cranial nerve stimulation therapy can provide significant improvement in important sleep related quality-of-life outcome measures and the effect is maintained across a 2-y follow-up period.

Palatoglossus coupling in selective upper airway stimulation

OBJECTIVES/HYPOTHESIS

Selective upper airway stimulation (sUAS) of the hypoglossal nerve is a useful therapy to treat patients with obstructive sleep apnea. Is it known that multiple obstructions can be solved by this stimulation technique, even at the retropalatal region. The aim of this study was to verify the palatoglossus coupling at the soft palate during stimulation.

STUDY DESIGN

Single-center, prospective clinical trail.

METHODS

Twenty patients who received an sUAS implant from April 2015 to April 2016 were included. A drug-induced sedated endoscopy (DISE) was performed before surgery. Six to 12 months after activation of the system, patients' tongue motions were recorded, an awake transnasal endoscopy was performed with stimulation turned on, and a DISE with stimulation off and on was done.

RESULTS

Patients with a bilateral protrusion of the tongue base showed a significantly increased opening at the retropalatal level compared to ipsilateral protrusions. Furthermore, patients with a clear activation of the geniohyoid muscle showed a better reduction in apnea-hypopnea index.

CONCLUSIONS

A bilateral protrusion of the tongue base during sUAS seems to be accompanied with a better opening of the soft palate. This effect can be explained by the palatoglossal coupling, due to its linkage of the muscles within the soft palate to those of the lateral tongue body.

LEVEL OF EVIDENCE

4 Laryngoscope, 127:E378-E383, 2017.

Hypoglossal nerve stimulation for obstructive sleep apnea: A review of the literature

Objective

To review the indications and clinical evidence supporting hypoglossal nerve stimulation (HNS) therapy for the treatment of moderate-to-severe obstructive sleep apnea (OSA).

Methods

Peer reviewed literature on hypoglossal nerve stimulation therapy for obstructive sleep apnea from 2001 to 2016.

Results

The only currently FDA-approved HNS device for the treatment of moderate-to-severe OSA is produced by Inspire Medical Systems, which recently published its 36-month outcomes data from its Stimulation Therapy for Apnea Reduction (STAR) trial. HNS therapy is currently indicated for moderate-to-severe OSA patients who are CPAP-intolerant, have a body mass index <32, apnea-hypopnea index <50, and without a concentric pattern of upper airway collapse on sleep endoscopy.

Conclusions

Data from the STAR trial suggests that a subset of OSA patients can achieve a significant therapeutic response from hypoglossal nerve stimulation. However, these results may be limited in their generalizability to the broader OSA population.

ENT-specific therapy of obstructive sleep apnoea in adults : A revised version of the previously published German S2e guideline

The German Society of Otorhinolaryngology, Head and Neck Surgery recently has released the abbreviated version of its scientific guideline "ENT-specific therapy of obstructive sleep apnoea (OSA) in adults", which has been updated in 2015 and can be found online at the Association of the Scientific Medical Societies (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF). A summary of the main recommendations is provided in this revised English version. All recommendations are based on a systematic literature research of articles published up until March 2014. Literature research followed the Cochrane Handbook for Systematic Literature Research to create Guidelines published by the German Cochrane Centre. Studies were evaluated with respect to their scientific value according to the recommendations of the Oxford Centre for Evidence-based Medicine, and grades of recommendation are provided regarding each intervention.

Origins of and implementation concepts for upper airway stimulation therapy for obstructive sleep apnea

Upper airway stimulation, specifically hypoglossal (CN XII) nerve stimulation, is a new, alternative therapy for patients with obstructive sleep apnea hypopnea syndrome who cannot tolerate positive airway pressure, the first-line therapy for symptomatic patients. Stimulation therapy addresses the cause of inadequate upper airway muscle activation for nasopharyngeal and oropharyngeal airway collapse during sleep. The purpose of this report is to outline the development of this first-in-class therapy and its clinical implementation. Another practical theme is assessment of the features for considering a surgically implanted device and the insight as to how both clinical and endoscopic criteria increase the likelihood of safe and durable outcomes for an implant and how to more generally plan for management of CPAP-intolerant patients. A third theme is the team building required among sleep medicine and surgical specialties in the provision of individualized neurostimulation therapy.