Extracranial transport of brain lymphatics via cranial nerve in human.

Extracranial waste transport from the brain interstitial fluid to the deep cervical lymph node (dCLN) is not extensively understood. The present study aims to show the cranial nerves that have a role in the transport of brain lymphatics vessels (LVs), their localization, diameter, and number using podoplanin (PDPN) and CD31 immunohistochemistry (IHC) and Western blotting. Cranial nerve samples from 6 human cases (3 cadavers, and 3 autopsies) were evaluated for IHC and 3 autopsies for Western blotting. The IHC staining showed LVs along the optic, olfactory, oculomotor, trigeminal, facial, glossopharyngeal, accessory, and vagus nerves. However, no LVs present along the trochlear, abducens, vestibulocochlear, and hypoglossal nerves. The LVs were predominantly localized at the endoneurium of the cranial nerve that has motor components, and LVs in the cranial nerves that had sensory components were present in all 3 layers. The number of LVs accompanying the olfactory, optic, and trigeminal nerves was classified as numerous; oculomotor, glossopharyngeal, vagus, and accessory was moderate; and facial nerves was few. The largest diameter of LVs was in the epineurium and the smallest one was in the endoneurium. The majority of Western blotting results correlated with the IHC. The present findings suggest that specific cranial nerves with variable quantities provide a pathway for the transport of wastes from the brain to dCLN. Thus, the knowledge of the transport of brain lymphatics along cranial nerves may help understand the pathophysiology of various neurological diseases.

Effect of hypoglossal nerve stimulation on snoring: an evaluation using objective acoustic parameters.

STUDY OBJECTIVES: Hypoglossal nerve stimulation is an established therapy for sleep apnea syndrome. Whether or not this therapy on snoring and nighttime noise exposure is effective and how strong this effect may be has not been objectively investigated thus far and was the aim of this study. METHODS: In 15 participants (14 males; age: 30-72 years; mean: 51.7 years), polysomnography and acoustic measurements were performed before and after hypoglossal nerve stimulation. RESULTS: The therapy led to a significant improvement in sleep apnea (apnea-hypopnea index from 35.8 events/h to 11.2 events/h, P < .001). Acoustic parameters showed a highly significant reduction in the average sound pressure level (42.9 db[A] to 36.4 db[A], P < .001), averaged sound energy, A-weighted (LAeq; 33.1 db[A] to 28.7 db[A], P < .001), snoring index (1,068 to 506, P < .001), percentage snoring time (29.7-14.1%, P < .001), and psychoacoustic snore score, the latter being a measure of annoyance due to snoring (47.9 to 24.5, P < .001). CONCLUSIONS: This study was able to show for the first time by means of objective acoustic and psychoacoustic parameters that hypoglossal nerve stimulation can not only cause a significant improvement in sleep apnea but also has a positive effect on snoring and thus noise annoyance experienced by the bed partner. CLINICAL TRIAL REGISTRATION: Registry: German Clinical Trials Register; Name: Effect of Hypoglossal Nerve Stimulation on Snoring: An Evaluation Using Objective Acoustic Parameters; URL: https://drks.de/search/de/trial/DRKS00032354; Identifier: DRKS00032354. CITATION: Fischer R, Vielsmeier V, Kuehnel TS, et al. Effect of hypoglossal nerve stimulation on snoring: an evaluation using objective acoustic parameters. J Clin Sleep Med. 2024;20(3):363-370.

Right Versus Left Cuff Position for Upper Airway Stimulation.

OBJECTIVE: Upper airway stimulation (UAS) is a treatment option for obstructive sleep apnea in which electrical stimulation is applied to the hypoglossal nerve. Nerve branches that control tongue protrusion are located inferiorly. Due to positioning, left-sided implants are typically placed with an inferiorly oriented electrode cuff (L-down) as opposed to superiorly on the right (R-up). In this study, we assess the impact of left- versus right-sided UAS on patient outcomes. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary Academic Medical Center. METHODS: Patients who underwent UAS implantation between 2016 and 2021 with an L-down or R-up oriented cuff as confirmed by X-ray were included. Data were collected retrospectively. Most recent sleep study variables were used for analysis. RESULTS: A total of 190 patients met the inclusion criteria. The average age was 61.0 ± 11.0 years, with 55 (28.9%) females. L-down orientation was present in 21 (11.1%) patients vs 169 (88.9%) R-up. Indications for L-down included hunting/shooting (n = 15), prior radiation/surgery (n = 4), central port (n = 1), and brachial plexus injury (n = 1). Adherence was higher among L-down patients (47.1 vs 41.0 hours use/week, P = .037) in univariate analysis, with a similar time to adherence data collection (4.4 vs 4.2 months, P = .612), though this finding was not maintained in the multivariate regression analysis. Decrease in apnea-hypopnea index (21.3 vs 22.8, P = .734), treatment success (76.5% vs 84.0%, P = .665), functional threshold (1.5 vs 1.6, P = .550), therapeutic amplitude (2.3 vs 2.4, P = .882), and decrease in Epworth Sleepiness Scale (4.9 vs 2.6, P = .060) were not significantly different between cohorts. CONCLUSION: This study is the first to examine the orientation of the UAS electrode cuff concerning the electrodes' natural position and the potential effect on postoperative outcomes. Our study found no significantly different treatment outcomes between the L-down versus R-up cohort, with the exception of device adherence, which was significantly higher in the L-down group on univariate analysis though not on multivariate analysis. Future studies with larger patient cohorts are needed to further investigate this potential relationship between treatment outcomes and electrode cuff orientation.

Pediatric Down Syndrome Upper Airway Stimulation: Patient Selection and Post-Implantation Optimization.

OBJECTIVE: The Food and Drug Administration recently approved upper airway stimulation (UAS) for children with Down Syndrome and persistent obstructive sleep apnea who meet certain inclusion and exclusion criteria. Although there is a robust experience with this therapy in the adult population, established protocols used in adults are not directly transferrable to a complex pediatric population. This review aims to combine the protocols from several institutions for patient selection and postimplantation optimization, including a protocol for Drug-Induced Sleep Endoscopy in children with Down Syndrome, preactivation threshold measurements, device titration, and follow-up sleep studies. STUDY DESIGN: Expert panel development of best Practice algorithm. SETTING: Multi-institutional investigator review. METHODS: An expert panel was assembled of pediatric otolaryngologists with extensive experience in hypoglossal nerve stimulation in children with Down Syndrome. Thirty statements were created during an initial drafting session. A modified Delphi method was used assess consensus among the panel. RESULTS: After 2 rounds of Delphi surveys, 29 statements met criteria for consensus. One statement did not meet consensus. The statements were grouped into several categories to facilitate presentation. CONCLUSIONS: A standardized approach to UAS for children with Down Syndrome must take into account the unique challenges inherent to treating a complex pediatric population with a high rate of sensory processing disorders. This expert panel has met consensus on several statements that will guide clinicians as this novel therapy is adopted.

Snoring Patterns During Hypoglossal Nerve Stimulation Therapy Up-Titration.

Longitudinal snoring changes can be captured using a mobile phone application. During hypoglossal nerve stimulator (HNS) therapy up-titration, increasing stimulation voltage was associated with reduced snoring frequency and intensity in this case series of six patients. Laryngoscope, 134:987-992, 2024.

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

INTRODUCTION: The Hypoglossal Nerve Stimulator (HNS) is a novel therapy that has been extensively studied in adults and more recently, it has been incorporated in children with Down Syndrome (DS) with persistent obstructive sleep apnea after adenotonsillectomy and trial of continuous positive airway pressure treatment. This systematic review article aims to examine the existing literature on HNS use in children to explore the benefits, efficacy, and parental experiences. METHODS: MEDLINE, Web of Science and EMBASE were searched to include all studies published up to March 2nd, 2023, on the topic of HNS use in pediatric population under 21 years old. RESULTS: A total of 179 studies were initially identified from which 10 articles were consistent with the inclusion criteria. Nine articles addressed outcomes after implantation of the HNS device in children with DS and 1 article explored the parental experiences. Findings were similar across studies where after implantation of HNS, there was marked improvement in polysomnographic outcomes and quality of life scores with high level of compliance. CONCLUSIONS: HNS holds promise as an effective treatment option for pediatric patients with DS and persistent OSA after AT and CPAP trials. It significantly improves sleep-disordered breathing, quality of life, and neurocognitive measures, leading to substantial and sustained benefits for these children. While the findings are encouraging, further research is needed to explore the potential of HNS in other pediatric populations without DS and to raise awareness among healthcare providers about this treatment option. Overall, HNS may offer significant long-term benefits for the overall well-being and health of pediatric patients with DS and persistent OSA.

Hypoglossal Nerve Stimulation and Cardiovascular Outcomes for Patients With Obstructive Sleep Apnea: A Randomized Clinical Trial.

Importance: Sham-controlled trials are needed to characterize the effect of hypoglossal nerve stimulation (HGNS) therapy on cardiovascular end points in patients with moderate-severe obstructive sleep apnea (OSA). Objective: To determine the effect of therapeutic levels of HGNS, compared to sham levels, on blood pressure, sympathetic activity, and vascular function. Design, Setting, and Participants: This double-blind, sham-controlled, randomized crossover therapy trial was conducted from 2018 to 2022 at 3 separate academic medical centers. Adult patients with OSA who already had an HGNS device implanted and were adherent and clinically optimized to HGNS therapy were included. Participants who had fallen asleep while driving within 1 year prior to HGNS implantation were excluded from the trial. Data analysis was performed from January to September 2022. Interventions: Participants underwent a 4-week period of active HGNS therapy and a 4-week period of sham HGNS therapy in a randomized order. Each 4-week period concluded with collection of 24-hour ambulatory blood pressure monitoring (ABPM), pre-ejection period (PEP), and flow-mediated dilation (FMD) values. Main Outcomes and Measures: The change in mean 24-hour systolic blood pressure was the primary outcome, with other ABPM end points exploratory, and PEP and FMD were cosecondary end points. Results: Participants (n = 60) were older (mean [SD] age, 67.3 [9.9] years), overweight (mean [SD] body mass index, calculated as weight in kilograms divided by height in meters squared, 28.7 [4.6]), predominantly male (38 [63%]), and had severe OSA at baseline (mean [SD] apnea-hypopnea index, 33.1 [14.9] events/h). There were no differences observed between active and sham therapy in 24-hour systolic blood pressure (mean change on active therapy, -0.18 [95% CI, -2.21 to 1.84] mm Hg), PEP (mean change on active therapy, 0.11 [95% CI, -5.43 to 5.66] milliseconds), or FMD (mean change on active therapy, -0.17% [95% CI, -1.88% to 1.54%]). Larger differences between active and sham therapy were observed in a per-protocol analysis set (n = 20) defined as experiencing at least a 50% reduction in apnea-hypopnea index between sham and active treatment. Conclusions and Relevance: In this sham-controlled HGNS randomized clinical trial, mean 24-hour systolic blood pressure and other cardiovascular measures were not significantly different between sham and active HGNS therapy. Several methodologic lessons can be gleaned to inform future HGNS randomized clinical trials. Trial Registration: ClinicalTrials.gov Identifier: NCT03359096.

Mitigating Infection Risk in Upper Airway Stimulation.

OBJECTIVE: This study aims to define the incidence of infection with upper airway stimulation (UAS) devices requiring explantation in a single academic center and identify factors that may influence the risk of infection. METHODS: A database of patients who underwent UAS at a single tertiary referral academic center from 2017 to 2021 was retrospectively reviewed to identify patients who developed surgical site infections, with and without subsequent explantation. Additional data for cases complicated by infection was extracted from the electronic medical record (EMR) and included: demographic information, medical history, complications and management, and overall outcomes. In March 2021, 2 modifications to infection control protocols were implemented: double skin preparation with Betadine and chlorhexidine, and MRSA decolonization. Statistical analysis was performed to compare infectious risk before and after these protocol changes. RESULTS: In the study period, 215 patients underwent UAS in the specified time period and 3 cases (1.4%) of postoperative infections were identified, all of which required explantation. The infection rate did not significantly change after modifications to the surgical prep protocol (P = .52). CONCLUSIONS: While no significant difference in infection risk was noted after modifying infection control protocols, additional longer-term study is warranted to elucidate effective infection reduction strategies.

Palate shape is associated with Unilateral Hypoglossal Nerve Stimulation Outcomes.

OBJECTIVE: The aim was to determine the potential association between palate shape and unilateral hypoglossal nerve stimulation (HNS) outcomes. METHODS: Preoperative drug-induced sleep endoscopy (DISE) videos were reviewed and scored by 3 blinded reviewers to determine airway narrowing at the hard-soft palate junction (HP), soft palate genu, and inferior velum, as described by Woodson (2014). Scoring was as follows: 1-open airway, 2-narrow, 3-severe narrowing. Overall palate shape (oblique, intermediate, or vertical) was determined based on prior criteria. Successful surgical treatment was defined by the HNS titration polysomnogram as a reduction of ≥50% in the apnea-hypopnea index (AHI) to <15 events/h. RESULTS: Of 332 adults, the majority was male (77%) with an average BMI of 29.2 ± 3.6 kg/m2 . Overall success rate was 73%. Success rate was lower in patients with vertical palate shape compared with the other shapes (56% vs. 75%, p = 0.029). HP score 3 compared with scores 2 and 1 was associated with lower success rates (60% vs. 76%, p = 0.028), but genu and velum scores were not associated with outcomes. Patients with both HP score 3 and complete oropharyngeal lateral wall-related obstruction had notably worse outcomes (22% vs. 74%, p = 0.026). HP score 3 (OR 0.45, 95%CI 0.22-0.92) and vertical palate shape (OR 0.33, 95%CI 0.15-0.78) were independently associated with lower odds of surgical response after adjustment for DISE findings, age, gender, and BMI. CONCLUSION: Vertical palate shape and narrowing at the hard-soft palate junction are independently associated with lower HNS surgical success rates. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:981-986, 2024.

Hypoglossal Nerve Stimulator in the Active Duty Population: Military Readiness and Satisfaction.

INTRODUCTION: Because inadequate sleep impairs mission performance, the U.S. Army regards sleep as a core pillar of soldier readiness. There is an increasing incidence of obstructive sleep apnea (OSA) among active duty (AD) service members, which is a disqualifying condition for initial enlistment. Moreover, a new diagnosis of OSA in the AD population often prompts a medical evaluation board, and if symptomatic OSA proves refractory to treatment, this may result in medical retirement. Hypoglossal nerve stimulator implantation (HNSI) is a newer implantable treatment option, which requires minimal ancillary equipment to function and may provide a useful treatment modality to support AD service members while maintaining readiness in appropriate candidates. Because of a perception among AD service members that HNSI results in mandatory medical discharge, we aimed to evaluate the impact of HNSI on military career progression, maintenance of deployment readiness, and patient satisfaction. METHODS: The Department of Research Programs at the Walter Reed National Military Medical Center provided institutional review board approval for this project. This is a retrospective, observational study and telephonic survey of AD HNSI recipients. Military service information, demographics, surgical data, and postoperative sleep study results were collected from each patient.Additional survey questions assessed each service member's experience with the device. RESULTS: Fifteen AD service members who underwent HNSI between 2016 and 2021 were identified. Thirteen subjects completed the survey. The mean age was 44.8 years (range 33-61), and all were men. Six subjects (46%) were officers. All subjects maintained AD status following HNSI yielding 14.5 person-years of continued AD service with the implant. One subject underwent formal assessment for medical retention. One subject transferred from a combat role to a support role. Six subjects have since voluntarily separated from AD service following HNSI. These subjects spent an average of 360 (37-1,039) days on AD service. Seven subjects currently remain on AD and have served for an average of 441 (243-882) days. Two subjects deployed following HNSI. Two subjects felt that HSNI negatively affected their career. Ten subjects would recommend HSNI to other AD personnel. Following HNSI, of the eight subjects with postoperative sleep study data, five achieved surgical success defined as >50% reduction of apnea-hypopnea index and absolute apnea-hypopnea index value of <20. CONCLUSIONS: Hypoglossal nerve stimulator implantation for AD service members offers an effective treatment modality for OSA, which generally allows for the ability to maintain AD status, however: The impact on deployment readiness should be seriously considered and tailored to each service member based on their unique duties before implantation. Seventy-seven percent of HNSI patients would recommend it to other AD service members suffering from OSA.

Impact of Insomnia on Hypoglossal Nerve Stimulation Outcomes in the ADHERE Registry.

OBJECTIVE: We aimed to determine the preoperative prevalence of insomnia in the Adherence and Outcomes of Upper Airway Stimulation for OSA International Registry (ADHERE) and to examine serial sleep-related data longitudinally, in particular the Insomnia Severity Index (ISI), to compare outcomes between patients with no/subthreshold insomnia (ISI < 15) and moderate/severe insomnia (ISI ≥ 15) at baseline. METHODS: We analyzed observational data from ADHERE between March 2020 and September 2022. Baseline demographic and mental health (MH) data, apnea hypopnea index (AHI), ISI, and ESS (Epworth Sleepiness Scale) were recorded. At post-titration (PT) and final visits, AHI, ISI, ESS and nightly usage were compared between baseline ISI < 15 and ISI ≥ 15 subgroups. RESULTS: A baseline ISI was obtained in 928 patients (62% with ISI ≥ 15). Of the 578 and 141 patients reaching the 12- and 24-month time periods to complete PT and final visits, 292 (50.5%) and 91 (64.5%) completed the ISI, respectively. Baseline MH conditions were higher with ISI ≥ 15 than ISI < 15 (p < 0.001). AHI reduction and adherence did not differ between patients with baseline ISI ≥ 15 and ISI < 15. Patients with ISI ≥ 15 experienced greater improvement in ESS than ISI < 15 at post-titration and final visits (p = 0.014, 0.025). All patients had improved nocturnal, daytime, and overall ISI scores at follow-up visits (p < 0.001), especially for those with baseline ISI ≥ 15 compared with ISI < 15 (p < 0.05). CONCLUSION: HGNS therapy efficacy and adherence were similar between ISI severity subgroups at follow-up visits. Insomnia and sleepiness scores improved in all patients with HGNS therapy and to a greater degree in patients with baseline moderate/severe insomnia. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:471-479, 2024.

Should lateral wall collapse be a contraindication for hypoglossal nerve stimulation?

OBJECTIVE: The purpose of this study is to examine how lateral wall collapse affects treatment outcomes for hypoglossal nerve stimulation (HNS) patients. METHODS: Patients (n = 111) queried from a single surgeon's database of HNS cases were divided into groups based on their degree of oropharyngeal lateral wall collapse noted on drug-induced sleep endoscopy (DISE): Complete, Partial, None. For each group, apnea hypopnea index (AHI) reduction, Epworth Sleepiness Scale (ESS) score, stimulation voltage, average nightly usage, need for alternate device configuration/awake sleep endoscopy, and rate of surgical success were collected. Patients with Complete collapse were compared to those with Partial/None via Student's t-tests and Pearson's Chi-square test. RESULTS: Of the 111 eligible patients, 45 had complete, 30 partial, and 36 had no lateral oropharyngeal wall collapse. There were no statistically significant differences found between the Complete and Partial/None groups in terms of age, BMI, sex, AHI (pre and post-op), ESS (pre and post-op), voltage, alternate device configuration, or nightly adherence. Notably, a significantly greater number of the Partial/None group had surgical success (84.84 % vs 66.67 %, p = 0.024). CONCLUSIONS: Patients with Partial/None oropharyngeal collapse were significantly more likely than patients with Complete lateral wall collapse to see surgical success. There are many factors to weigh when assessing a patient's surgical candidacy, it is clear that complete lateral wall collapse at the level of the oropharynx is a negative predictor for success in HNS.

An unexpected complication of hypoglossal schwannoma surgery: Cerebrospinal fluid leakage-A case report and literature review.

BACKGROUND: Extracranial hypoglossal schwannoma is a rare tumor primarily treated with surgical excision. This article aims to highlight the potential for unexpected complications intraoperatively, such as cerebrospinal fluid leakage from skullbase to neck. METHODS: A previously healthy 23-year-old male presented with tongue numbness. Magnetic resonance imaging revealed a 17 × 20 mm nodular lesion adjacent to the cervical segment of the internal carotid artery. Surgical excision was scheduled due to suspicion of a neurogenic tumor. RESULTS: Intraoperatively, despite careful handling, cerebrospinal fluid leakage was observed. Manipulation of the mass caused detachment of proximal nerve fibers, potentially indicating avulsion of the hypoglossal nerve from the brainstem or nearby. Clear fluid leakage from the skull base was also noted. CONCLUSION: Thorough preoperative evaluation and patient education regarding potential complications are crucial. This article presents an unexpected complication encountered during surgical excision of extracranial hypoglossal schwannoma, emphasizing the need for awareness and preparedness in such cases.

Hypoglossal Nerve Transfer for Facial Nerve Paralysis: A Systematic Review and Meta-Analysis.

Background: Hypoglossal-facial nerve (12-7) anastomosis can restore symmetry and voluntary movement on the face in patients with facial nerve paralysis. Traditional 12-7 transfer includes direct end-to-end nerve anastomosis, sacrificing the entire hypoglossal nerve. Contemporary, end-to-side anastomosis, or split anastomosis techniques limit tongue morbidity by preserving some hypoglossal nerve. Direct outcome comparisons between these techniques are limited. Objective: To compare reported outcomes of facial movement, tongue, speech, and swallow outcomes among the different types of hypoglossal-facial nerve anastomosis schemes. Evidence Review: For this systematic review and meta-analysis, a comprehensive strategy was designed to search PubMed, Scopus, and the Cochrane Database from inception to January 2021, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, reporting guideline yielding 383 results. Any participant who underwent 12-7 transfer using any of the three techniques, with or without an interposition graft, and had documented preoperative and postoperative evaluation of facial nerve function with a validated instrument such as House-Brackmann (HB), was considered for inclusion. Secondary outcomes of synkinesis, tongue atrophy, and speech or swallowing dysfunction were also compared. Forty-nine studies met inclusion criteria, representing data from 961 total patients who underwent 12-7 transfer. Results: The proportion of good HB outcomes (HB I-III) did not differ by anastomosis type: End-to-side and end-to-end anastomosis (73% vs. 59%, p = 0.07), split and end-to-end anastomosis (62% vs. 59%, p = 0.88), and end-to-side anastomosis and split anastomosis (73% vs. 62%, p = 0.46). There was no difference in reported synkinesis rates between the anastomosis types. However, end-to-side anastomosis (z = 6.55, p < 0.01) and split anastomosis (z = 3.58, p < 0.01) developed less tongue atrophy than end-to-end anastomosis. End-to-side anastomosis had less speech/swallowing dysfunction than end-to-end anastomosis (z = 3.21, p < 0.01). Conclusion: End-to-side and split anastomoses result in similar HB facial nerve outcomes as the traditional end-to-end 12-7 anastomosis. End-to-side anastomosis has decreased complications of tongue atrophy and speech/swallow dysfunction compared to end-to-end anastomosis. In addition, split anastomosis has decreased rates of tongue atrophy compared to end-to-end anastomosis.

Challenges and adverse events in pediatric hypoglossal nerve stimulation.

INTRODUCTION: Hypoglossal nerve stimulation was recently FDA approved for use in children with Down Syndrome and persistent obstructive sleep apnea. Although there is a robust experience in hypoglossal nerve stimulation in adults, we observed several challenges that are unique to providing this therapy to a complex pediatric population with a high rate of sensory processing disorders. We sought to review the adverse events and challenges to inform clinicians as hypoglossal nerve stimulation becomes a more accessible option for this complex population. METHODS: Retrospective case series of children with Down Syndrome and persistent OSA who underwent hypoglossal nerve stimulation. Inclusion and exclusion criteria included Down Syndrome, age 10-22 years, persistent severe OSA after adenotonsillectomy (AHI>10 with <25 % central or mixed events), inability to tolerate positive airway pressure, and absence of concentric palatal collapse on sleep endoscopy. Patients were identified and their charts were reviewed. Adverse events and their subsequent management were recorded. The major outcome variable was the total number of adverse events. RESULTS: A total of 53 patients underwent implantation of a hypoglossal nerve stimulator; 35 (66 %) patients were male and the average age at implantation was 15.1 years (standard deviation 3.0y). A total of 30 adverse events were noted, including 17 nonserious and 13 serious. The most common nonserious complications included temporary tongue discomfort, rash at the surgical site, and cellulitis. Serious complications included readmission (for cellulitis, pain, and device extrusion), reoperation (most commonly for battery depletion) and pressure ulcer formation. CONCLUSION: Hypoglossal nerve stimulation provides a much-needed therapy for children with DS and persistent OSA after adenotonsillectomy. Although there is a robust experience in providing this treatment to adults, many considerations must be made when adapting this technology to a pediatric population with a high rate of sensory processing disorders.

Hypoglossal Nerve Stimulation Effects on Obstructive Sleep Apnea Over Time: A Systematic Review and Meta-analysis.

OBJECTIVES: This study aimed to determine the efficacy of hypoglossal nerve stimulation (HGS) in the treatment of obstructive sleep apnea. DATA SOURCES: PubMed, Cochrane database, Embase, Web of Science, SCOPUS, and Google Scholar. REVIEW METHODS: Five databases were reviewed to identify relevant studies that measured polysomnography parameters such as the apnea-hypopnea index (AHI) and oxygen desaturation index, as well as quality of life and functional outcomes of sleep questionnaire scores, before and after HGS. RESULTS: In total, 44 studies involving 8670 patients met the inclusion criteria. At 12 months after treatment, approximately 47%, 72%, and 82% of patients achieved AHI values of <5, < 10, and <15, respectively. The reported clinical success rates according to Sher criteria were 80% within 12 months and 73% between 12 and 36 months. While the favorable effects exhibited a gradual reduction up to 12 months postimplantation, they generally maintained a consistent level between the 12th and 36th months, as assessed by AHI < 5, <15, and success rate according to Sher criteria. CONCLUSION: HGS can enhance quality of life scores and polysomnography outcomes in obstructive sleep apnea patients. Although the positive effects gradually decreased until 12 months after implantation, they generally remained consistent between 12 and 36 months.

Chronic intermittent hypoxia attenuates noradrenergic innervation of hypoglossal motor nucleus.

The state-dependent noradrenergic activation of hypoglossal motoneurons plays an important role in the maintenance of upper airway patency and pathophysiology of obstructive sleep apnea (OSA). Chronic intermittent hypoxia (CIH), a major pathogenic factor of OSA, contributes to the risk for developing neurodegenerative disorders in OSA patients. Using anterograde tracer, channelrhodopsin-2, we mapped axonal projections from noradrenergic A7 and SubCoeruleus neurons to hypoglossal nucleus in DBH-cre mice and assessed the effect of CIH on these projections. We found that CIH significantly reduced the number of axonal projections from SubCoeruleus neurons to both dorsal (by 68%) and to ventral (by73%) subregions of the hypoglossal motor nucleus compared to sham-treated animals. The animals' body weight was also negatively affected by CIH. Both effects, the decrease in axonal projections and body weight, were more pronounced in male than female mice, which was likely caused by less sensitivity of female mice to CIH as compared to males. The A7 neurons appeared to have limited projections to the hypoglossal nucleus. Our findings suggest that CIH-induced reduction of noradrenergic innervation of hypoglossal motoneurons may exacerbate progression of OSA, especially in men.

[Hypoglossal Stimulation: Indication, Surgical Technique and Clinical Results]. / Hypoglossus-Stimulation: Indikation, operative Technik und klinische Ergebnisse.

Hypoglossal stimulation is a safe and effective treatment option for patients with obstructive sleep apnea and unsuccessful PAP therapy. A number of criteria must be met for the indication: proof of failed PAP therapy and ineffectiveness of the other therapy alternatives, AHI of 15-65/h (a relevant number of central and/or mixed apneas should be excluded) and BMI up to max. 35kg/m2. In the case of the respiratory-synchronous and bilateral stimulation system, a complete concentric collapse at the velum level should currently be ruled out in DISE. In the future, stimulation of the branch of the ansa cervicalis innervating the sternothyroid muscle and the ramus internus of the superior laryngeal nerve could open up additional treatment options.

Minimally Invasive Hypoglossal Nerve Stimulator Enabled by ECG Sensor and WPT to Manage Obstructive Sleep Apnea.

A hypoglossal nerve stimulator (HGNS) is an invasive device that is used to treat obstructive sleep apnea (OSA) through electrical stimulation. The conventional implantable HGNS device consists of a stimuli generator, a breathing sensor, and electrodes connected to the hypoglossal nerve via leads. However, this implant is bulky and causes significant trauma. In this paper, we propose a minimally invasive HGNS based on an electrocardiogram (ECG) sensor and wireless power transfer (WPT), consisting of a wearable breathing monitor and an implantable stimulator. The breathing external monitor utilizes an ECG sensor to identify abnormal breathing patterns associated with OSA with 88.68% accuracy, achieved through the utilization of a convolutional neural network (CNN) algorithm. With a skin thickness of 5 mm and a receiving coil diameter of 9 mm, the power conversion efficiency was measured as 31.8%. The implantable device, on the other hand, is composed of a front-end CMOS power management module (PMM), a binary-phase-shift-keying (BPSK)-based data demodulator, and a bipolar biphasic current stimuli generator. The PMM, with a silicon area of 0.06 mm2 (excluding PADs), demonstrated a power conversion efficiency of 77.5% when operating at a receiving frequency of 2 MHz. Furthermore, it offers three-voltage options (1.2 V, 1.8 V, and 3.1 V). Within the data receiver component, a low-power BPSK demodulator was ingeniously incorporated, consuming only 42 µW when supplied with a voltage of 0.7 V. The performance was achieved through the implementation of the self-biased phase-locked-loop (PLL) technique. The stimuli generator delivers biphasic constant currents, providing a 5 bit programmable range spanning from 0 to 2.4 mA. The functionality of the proposed ECG- and WPT-based HGNS was validated, representing a highly promising solution for the effective management of OSA, all while minimizing the trauma and space requirements.

Hypoglossal canal: an osteological and morphometric study on a collection of dried skulls in an Italian population: clinical implications.

BACKGROUND: The hypoglossal canal is a dual bone canal at the cranial base near the occipital condyles. The filaments of the hypoglossal nerve pass through the canal. It also transmits the meningeal branch of the ascending pharyngeal artery, the venous plexus and meningeal branches of the hypoglossal nerve. The hypoglossal nerve innervates all the intrinsic and extrinsic muscles of the tongue except the palatoglossal and is fundamental in physiological functions as phonation and deglutition. A surgical approach to the canal requires knowledge of the main morphometric data by neurosurgeons. METHODS: The present study was carried out on 50 adult dried skulls: 31 males: age range 18-85 years; 19 females: age range 26-79 years. The skulls came from the ''Leonetto Comparini'' Anatomical Museum. The skulls belonged to people from Siena (Italy) and its surroundings (1882-1932) and, therefore, of European ethnicity. The present study reports (a) the osteological variations in hypoglossal canal (b) the morphometry of hypoglossal canal and its relationship with occipital condyles. One skull had both the right and left hypoglossal canals occluded and, therefore, could not be evaluated. None of the skulls had undergone surgery. RESULTS: We found a double canal in 16% of cases, unilaterally and bilaterally in 2% of cases. The mean length of the right and left hypoglossal canals was 8.46 mm. The mean diameter of the intracranial orifice and extracranial orifice of the right and left hypoglossal canals was 6.12 ± 1426 mm, and 6.39 ± 1495 mm. The mean distance from the intracranial end of the hypoglossal canal to the anterior and posterior ends of occipital condyles was 10,76 mm and 10,81 mm. The mean distance from the intracranial end of the hypoglossal canal to the inferior end of the occipital condyles was 7,65 mm. CONCLUSIONS: The study on the hypoglossal canal adds new osteological and morphometric data to the previous literature, mostly based on studies conducted on different ethnic groups.The data presented is compatible with neuroradiological studies and it can be useful for radiologists and neurosurgeons in planning procedures such as transcondilar surgery. The last purpose of the study is to build an Italian anatomical data base of the dimensions of the hypoglossal canal in dried skulls..