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

Feasibility of endovascular stimulation of the femoral nerve using a stent-mounted electrode array

Objective.Electrical stimulation of peripheral nerves has long been a treatment option to restore impaired neural functions that cannot be restored by conventional pharmacological therapies. Endovascular neurostimulation with stent-mounted electrode arrays is a promising and less invasive alternative to traditional implanted electrodes, which typically require invasive implantation surgery. In this study, we investigated the feasibility of endovascular stimulation of the femoral nerve using a stent-mounted electrode array and compared its performance to that of a commercially available pacing catheter.Approach.In acute animal experiments, a pacing catheter was implanted unilaterally in the femoral artery to stimulate the femoral nerve in a bipolar configuration. Electromyogram of the quadriceps and electroneurogram of a distal branch of the femoral nerve were recorded. After retrieval of the pacing catheter, a bipolar stent-mounted electrode array was implanted in the same artery and the recording sessions were repeated.Main Results.Stimulation of the femoral nerve was feasible with the stent-electrode array. Although the threshold stimulus intensities required with the stent-mounted electrode array (at 100-500µs increasing pulse width, 2.17 ± 0.87 mA-1.00 ± 0.11 mA) were more than two times higher than the pacing catheter electrodes (1.05 ± 0.48 mA-0.57 ± 0.28 mA), we demonstrated that, by reducing the stimulus pulse width to 100µs, the threshold charge per phase and charge density can be reduced to 0.22 ± 0.09µC and 24.62 ± 9.81µC cm-2, which were below the tissue-damaging limit, as defined by the Shannon criteria.Significance.The present study is the first to reportin vivofeasibility and efficiency of peripheral nerve stimulation using an endovascular stent-mounted electrode array.

Personalized multimodal management for severe obstructive sleep apnea in a patient intolerant of positive airway pressure with hypoglossal nerve stimulator and mandibular advancement device

Treatment of moderate to severe obstructive sleep apnea poses clinical challenges in persons with intolerance or inadequate response to traditional treatment modalities, including positive airway pressure and mandibular advancement devices. Hypoglossal nerve stimulation is a new treatment option, but few management guidelines exist when it is intolerable or ineffective. Combining several treatment modalities has been an effective strategy for improving symptoms, tolerance, and efficacy. We describe a patient intolerant to positive airway pressure therapy who had continued sleepiness, morning headaches, and snoring with a mandibular advancement device. He underwent hypoglossal nerve stimulation implantation but was intolerant of the voltages required to adequately control his obstructive sleep apnea. Multimodal management with hypoglossal nerve stimulation, mandibular advancement device, and positional therapy was successfully implemented to improve sleepiness, nocturnal symptoms, and the apnea-hypopnea index. This case highlights the personalization and adaptability of combination therapy to suit patient needs while effectively controlling obstructive sleep apnea.

CITATION

Lowery MM, Rundo JV, Walia HK, Shah V. Personalized multimodal management for severe obstructive sleep apnea in a patient intolerant of positive airway pressure with hypoglossal nerve stimulator and mandibular advancement device. J Clin Sleep Med. 2023;19(2):403-408.

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.

Pacing therapies for sleep apnea and cardiovascular outcomes: A systematic review

PURPOSE

Phrenic and hypoglossal nerve pacing therapies have shown benefit in sleep apnea. We sought to analyze the role of pacing therapies in sleep apnea and their impact on heart failure.

METHODS

A comprehensive literature search in PubMed and Google Scholar from inception to August 5, 2019, was performed. A meta-analysis was performed using fixed effects model to calculate mean difference (MD) with 95% confidence interval (CI).

RESULTS

Six studies were eligible and included 626 patients, of whom 334 were in the control arm and 393 were in the experimental arm. Phrenic nerve pacing (MD - 23.20 events/h, 95% CI - 27.96 to - 18.44, p < 0.00001) and hypoglossal nerve pacing (MD - 20.24 events/h, 95% CI - 23.22 to - 17.27, p < 0.00001) were associated with improvements in apnea-hypopnea index (AHI). Phrenic nerve pacing was associated with a trend towards improvements in left ventricular ejection fraction (MD 3.95%, 95% CI - 0.04 to 7.94, p = 0.05). Hypoglossal and phrenic nerve pacing were associated with improvements in the quality of life as assessed by improvements in Epworth sleepiness scale (MD 3.71 points, 95% CI 2.89 to 4.54, p < 0.00001).

CONCLUSIONS

Our analysis suggests that phrenic and hypoglossal nerve pacing improves AHI and quality of life with a trend towards improvement in left ventricular ejection fraction, especially in central sleep apnea. Complications were high but future refinement in technology will likely improve clinical outcomes and minimize complications.

Advances in Treatment of Sleep-Disordered Breathing

BACKGROUND

Sleep-disordered breathing, composed of obstructive sleep apnea (OSA) and central sleep apnea (CSA), affects millions of people worldwide carrying with it significant morbidity and mortality. Diagnosis is made by polysomnography, and severity of sleep apnea is determined by the apnea-hypopnea index (AHI). Positive airway pressure (PAP) therapy has been the gold standard in treating both OSA and CSA. PAP therapy can greatly reduce AHI burden as well as morbidity and mortality and improve quality of life.

AREAS OF UNCERTAINTY

However, patients report difficulties adhering to PAP therapy because of discomfort with mask interface, sensation of excessive pressure, and claustrophobia. Although other options exist to treat sleep apnea, such as mandibular advancement oral appliance devices, positional therapy, and surgery, these additional therapeutic modalities as current options have limitations. Emerging technology is now available to overcome hindrances to standard therapy.

DATA SOURCES

A literature search was performed from the following databases: PubMed, Cochrane Library (Cochrane Database of Systematic Reviews), and Cochrane Central Register of Controlled Trials, and FDA device database (clinicaltrial.gov).

THERAPEUTIC ADVANCES

Other modalities of treating sleep-disordered breathing now include the hypoglossal nerve stimulator, which stimulates the hypoglossal nerve during sleep to alleviate airflow obstruction by contracting the genioglossus muscle thus treating OSA. Similarly, the phrenic nerve stimulator restores a more stable breathing pattern during sleep by stimulating the phrenic nerve to activate the diaphragm during CSA. Both nerve stimulators have been shown to reduce AHI severity and improve quality of life for patients suffering from sleep-disordered breathing.

CONCLUSIONS

PAP therapy, although the gold standard, has limitations in the treatment of sleep apnea. New modalities such as hypoglossal nerve stimulator and phrenic nerve stimulator may help to overcome difficulties with adherence and offer new options for treatment of both obstructive and central sleep apnea.

Model-based geometrical optimisation and in vivo validation of a spatially selective multielectrode cuff array for vagus nerve neuromodulation

BACKGROUND

Neuromodulation by electrical stimulation of the human cervical vagus nerve may be limited by adverse side effects due to stimulation of off-target organs. It may be possible to overcome this by spatially selective stimulation of peripheral nerves. Preliminary studies have shown this is possible using a cylindrical multielectrode human-sized nerve cuff in vagus nerve selective neuromodulation.

NEW METHOD

The model-based optimisation method for multi-electrode geometric design is presented. The method was applied for vagus nerve cuff array and suggested two rings of 14 electrodes, 3 mm apart, with 0.4 mm electrode width and separation and length 0.5-3 mm, with stimulation through a pair in the same radial position on the two rings. The electrodes were fabricated using PDMS-embedded stainless steel foil and PEDOT: pTS coating.

RESULTS

In the cervical vagus nerve in anaesthetised sheep, it was possible to selectively reduce the respiratory breath rate (RBR) by 85 ± 5% without affecting heart rate, or selectively reduce heart rate (HR) by 20 ± 7% without affecting respiratory rate. The cardiac- and pulmonary-specific sites on the nerve cross-sectional perimeter were localised with a radial separation of 105 ± 5 degrees (P < 0.01, N = 24 in 12 sheep).

CONCLUSIONS

Results suggest organotopic or function-specific organisation of neural fibres in the cervical vagus nerve. The optimised electrode array demonstrated selective electrical neuromodulation without adverse side effects. It may be possible to translate this to improved treatment by electrical autonomic neuromodulation for currently intractable conditions.

Maxillomandibular Advancement for the Treatment of Obstructive Sleep Apnea in Patients With Normal or Class I Malocclusion

BACKGROUND

Maxillomandibular advancement is an effective surgical option for obstructive sleep apnea (OSA) that achieves enlargement of the upper airway by physically expanding the facial skeleton. The authors sought to determine whether an advancement of 10 mm predicts surgical success and if any correlation existed between the magnitude of mandibular/maxillary advancement and improvement in polysomnography metrics using aggregated individual patient data from multiple studies.

METHODS

A search of the PubMed database was performed to identify relevant articles that included preoperative and postoperative polysomnography data and measurements of the advancement of both the maxillary and mandibular portions of the face in patients with normal or class I malocclusion. Each patient was stratified into "Success" or "Failure" groups based on criteria defining a "Success" as a 50% preoperative to post-operative decrease in AHI or RDI and a post-operative AHI or RDI <20.

RESULTS

A review of the PubMed database yielded 162 articles. Review of these resulted in 9 manuscripts and a total of 109 patients who met the inclusion criteria. There was no statistically significant difference in the amount of anterior advancement of either the mandible (P = 0.96) or the maxilla (P = 0.23) between the "Success" or "Failure" groups.

CONCLUSIONS

While there is a paucity of individual data available, the current data does not support an ideal amount of maxillary or mandibular advancement that is required to obtain a surgical success in the treatment of OSA. Until a multicenter, prospective, randomized trial is performed, surgical planning should be tailored to patient-specific anatomy to achieve the desired result.

Upper airway stimulation as an alternative to maxillomandibular advancement for obstructive sleep apnoea in a patient with dentofacial deformity: case report with literature review

Obstructive sleep apnoea (OSA) is characterized by repeated upper airway collapse leading to oxygen desaturation resulting in cardiovascular and neurocognitive sequelae. Upper airway surgeries such as palatopharyngoplasty, tongue base surgery, and maxillomandibular advancement can improve patient tolerance of continuous positive airway pressure, quality of life, and the severity of OSA. Upper airway stimulation (UAS) of the hypoglossal nerve is a contemporary US Food and Drug Administration-approved treatment modality for OSA with a fundamentally different mechanism. We report the case of a 65-year-old male with a high body mass index, hypertension, diabetes, dentofacial deformity, and severe OSA. He presented with a respiratory distress index (RDI) of 89.1 events per hour, apnoea-hypopnoea index (AHI) of 82.7 events per hour, and minimum oxygen saturation of 75%. He chose to undergo UAS. Initially, complete concentric collapse of the velum was found during drug-induced sedation endoscopy, which was converted by palatopharyngoplasty to meet inclusion criteria for UAS. The patient achieved surgical cure with postoperative RDI and AHI of 2 events per hour with minimum oxygen saturation of 83%, and resolution of daytime somnolence. UAS is an effective surgical option to broaden the surgeon's ability to treat OSA, especially if facial skeletal surgery is contraindicated or declined by the patient with dentofacial deformity.

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.

Obstructive sleep apnea treatment in adults

Sleep-related breathing disorders are complex problems that decrease quality of life and increase morbidity and mortality in patients. Comprehensive evaluation is essential for selecting and planning obstructive sleep apnea (OSA) treatments. However, the many proposed OSA treatments are rarely compared in the literature. The literature on OSA consists largely of case series studies, and the paucity of controlled studies makes comparisons of OSA treatments difficult. This article provides a brief overview of the most common OSA interventions. Because of the controversies and unanswered questions about OSA treatments, further studies are needed to define what treatments are best for specific OSA patients.

Tongue Function: An Underrecognized Component in the Treatment of Obstructive Sleep Apnea with Mandibular Repositioning Appliance

Obstructive sleep apnea (OSA) is a common but still underrecognized disorder. A mandibular repositioning appliance (MRA) is used to treat OSA by advancing the mandible and thereby reducing the collapsibility of the upper airway. It has been found that an MRA increases the volume of the upper airway, especially the velopharyngeal area, in OSA patients. We hypothesize that this increase in the velopharyngeal volume is associated with an anterior displacement of the tongue, but likely not with a stretching of the soft tissue connecting the soft palate, lateral pharynx, palatopharyngeal arch, and mandible. Since the function and structure of the genioglossus and hypoglossal nerve are always abnormal in patients with OSA, the tongue does not always move simultaneously with the mandible when an MRA is being used. Oropharyngeal exercises, especially tongue exercises, can improve the quality of life of OSA patients, including reduction of daytime sleepiness and snoring, better quality of sleep, and partial decrease in the AHI. Further, in animal models, tongue exercise is also found to be effective in tongue function recovery and in the remodeling of the hypoglossal nucleus. We suggest that a combination of tongue exercises along with MRA is a promising approach for patients who do not respond to an MRA alone.

The Bidirectional Relationship Between Obstructive Sleep Apnea and Metabolic Disease

Obstructive sleep apnea (OSA) is a common sleep disorder, effecting 17% of the total population and 40-70% of the obese population (1, 2). Multiple studies have identified OSA as a critical risk factor for the development of obesity, diabetes, and cardiovascular diseases (3-5). Moreover, emerging evidence indicates that metabolic disorders can exacerbate OSA, creating a bidirectional relationship between OSA and metabolic physiology. In this review, we explore the relationship between glycemic control, insulin, and leptin as both contributing factors and products of OSA. We conclude that while insulin and leptin action may contribute to the development of OSA, further research is required to determine the mechanistic actions and relative contributions independent of body weight. In addition to increasing our understanding of the etiology, further research into the physiological mechanisms underlying OSA can lead to the development of improved treatment options for individuals with OSA.