Crossed motor innervation of the base of human tongue

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

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

Intraoperative Neuromonitoring of Hypoglossal Nerves Using Transcranial and Direct Electrical Stimulation During Extracranial Internal Carotid Artery Surgery

BACKGROUND

We explored whether the electromyogram (EMG) and the motor evoked potential (MEP) are useful for monitoring the function of the hypoglossal nerve during surgery targeting the cervical segment of the internal carotid artery.

METHODS

The present study included 6 patients with internal carotid arterial stenosis (1 patient underwent bilateral surgeries) and 1 patient with a cervical carotid artery aneurysm. In 5 of the 8 procedures, the EMGs were recorded. We examined whether changes in the MEP and/or EMG were capable of predicting postoperative hypoglossal nerve deficits.

RESULTS

None of the 6 patients who underwent a total of 7 carotid endarterectomy (CEA) procedures experienced postoperative hypoglossal nerve morbidity. In 2 of the 7 procedures, the MEP disappeared or decreased significantly during CEA. In all 4 cases in which the hypoglossal nerve was directly stimulated during CEA, stable and reproducible EMGs were obtained throughout the manipulation of the internal carotid artery. Hypoglossal nerve morbidity was observed in the one case that underwent aneurysm removal and end-to-end anastomosis of the internal carotid artery. In this case, while the MEP decreased significantly during the operation, the EMG showed true-positive results and false-negative results, depending on the stimulation site.

CONCLUSIONS

The monitoring of hypoglossal nerve function using EMG appears to be accurate if an appropriate stimulation site is selected. Hypoglossal nerve monitoring using MEP can produce false-positive results. Combined monitoring using both MEP and EMG is recommended in cases where exposure of the hypoglossal nerve is expected to be technically difficult.

Differences between Maximum Tongue Force in Women Suffering from Chronic and Asymptomatic Temporomandibular Disorders-An Observational Study

Background: Temporomandibular disorders are craniofacial disorders characterized by the presence of chronic pain in masticatory muscles, with higher incidence in the women population. There is little research that has studied tongue force related to temporomandibular disorders, but there are a lot of studies that have demonstrated the impact of tongue force in vital functions, such as chewing, swallowing, phonation, or breathing. According to this, the aim of this study was to compare the maximum force of the tongue between females with chronic temporomandibular disorders and asymptomatic females. We also wanted to establish whether any relationship existed between the pain and fatigue versus the maximum force developed in females with chronic temporomandibular disorders. Material and methods: A cross-sectional study of 67 women between the ages of 18 and 65 years old was performed. The included women were assigned to one of two groups, according to whether they had chronic temporomandibular disorders or not. The procedure was the same for both groups. Outcome measures included the maximum tongue force, intensity of perceived orofacial pain, and intensity of perceived orofacial fatigue. Results: The results showed significant statistical differences for the maximum tongue force measurement between the chronic temporomandibular disorders group and the control group (p < 0.05) for all the movements, except the lip pressure measurement. Furthermore, the analysis revealed significant statistical differences between the intensity of perceived orofacial fatigue between the groups (p < 0.05). Moreover, the data showed no significant correlations between variables. Conclusion: The study found significant differences in maximum tongue force when comparing women with chronic temporomandibular disorders and asymptomatic women (being superior in these). Likewise, we found that the intensity of perceived orofacial fatigue after tongue exercises showed significant differences between groups. However, this study reveals no correlations between the intensity of perceived orofacial pain and fatigue and the maximum tongue force.

Intraoperative identification of mixed activation profiles during hypoglossal nerve stimulation

STUDY OBJECTIVES

The effectiveness of hypoglossal nerve stimulation (HGNS) in the treatment of obstructive sleep apnea (OSA) depends on the selective stimulation of nerve fibers that innervate the tongue muscles that produce tongue protrusion (genioglossus) and stiffening (transverse/vertical) while avoiding fibers that innervate muscles that produce tongue retraction (styloglossus/hyoglossus). Postoperative treatment failures can be related to mixed activation of retractor and protrusor muscles, despite intraoperative efforts to identify and avoid nerve fibers that innervate the retractor muscles. This study describes a novel intraoperative protocol that more optimally identifies mixed activation by utilizing an expanded set of stimulation/recording parameters.

METHODS

This study was a case series in a university hospital setting of patients undergoing unilateral hypoglossal nerve stimulation implantation for obstructive sleep apnea. Data included electromyographic responses in the genioglossus and styloglossus/hyoglossus to intraoperative stimulation with an implantable pulse generator using unipolar (- - -, o-o) and bipolar (+-+) settings.

RESULTS

In a subset of patients (3/55), low-intensity unipolar implantable pulse generator stimulation revealed significant mixed activation of the styloglossus/hyoglossus and genioglossus muscles that was not evident under standard bipolar implantable pulse generator stimulation conditions. Additional surgical dissection and repositioning of the electrode stimulation cuff reduced mixed activation.

CONCLUSIONS

A novel intraoperative neurophysiological monitoring protocol was able to detect significant mixed activation during hypoglossal nerve stimulation that was otherwise absent using standard parameters. This enabled successful electrode cuff repositioning and a dramatic reduction of mixed activation.

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

PURPOSE

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

RESULTS

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

CONCLUSION

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

Contralateral Tongue Muscle Activation during Hypoglossal Nerve Stimulation

OBJECTIVE

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

STUDY DESIGN

Prospective case series.

SETTING

Tertiary care medical center.

SUBJECTS AND METHODS

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

RESULTS

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

CONCLUSION

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

The Five Diaphragms in Osteopathic Manipulative Medicine: Myofascial Relationships, Part 1

Working on the diaphragm muscle and the connected diaphragms is part of the respiratory-circulatory osteopathic model. The breath allows the free movement of body fluids and according to the concept of this model, the patient's health is preserved thanks to the cleaning of the tissues by means of the movement of the fluids (blood, lymph). The respiratory muscle has several systemic connections and multiple functions. The founder of osteopathic medicine emphasized the importance of the thoracic diaphragm and body health. The five diaphragms (tentorium cerebelli, tongue, thoracic outlet, thoracic diaphragm and pelvic floor) represent an important tool for the osteopath to evaluate and find a treatment strategy with the ultimate goal of patient well-being. The two articles highlight the most up-to-date scientific information on the myofascial continuum for the first time. Knowledge of myofascial connections is the basis for understanding the importance of the five diaphragms in osteopathic medicine. In this first part, the article reviews the systemic myofascial posterolateral relationships of the respiratory diaphragm; in the second I will deal with the myofascial anterolateral myofascial connections.

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.

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.

The Anatomical Relationships of the Tongue with the Body System

The tongue plays a fundamental role in several body functions such as swallowing, breathing, speaking, and chewing. Its action is not confined to the oral cavity, but it affects lower limb muscle strength and posture. The tongue is an organ that has an autocrine/paracrine mechanism of action to synthesize different substances to interact with the whole body; according to a line of thought, it is also an extension of the enteric system. The aim of this study was to review the functions of the tongue and its anatomical association with the body system. According to the authors' knowledge, this is the first scientific article focusing on the tongue in a systemic context. In a clinical evaluation, connections with the tongue should be considered to optimize the clinical examination of the tongue and therefore enhance rehabilitation programs and therapeutic results.

Tratamiento quirúrgico por otorrinolaringología en el síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

El síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) se caracteriza por la obstrucción parcial o el colapso total de la vía aérea superior, de manera intermitente y repetitiva, por lo que, en un principio, se vio el manejo quirúrgico como una alternativa curativa para esta patología. Sin embargo, en la actualidad se reconoce que la cirugía, aun sin lograr tasas de efectividad muy altas de manera consistente, sí mejora la tolerancia y adaptación a la terapia de presión positiva, la cual sigue siendo la primera línea de manejo.Así, el primer paso antes de pensar en cualquier procedimiento quirúrgico es un adecuado diagnóstico topográfico, de modo que siempre se debe realizar una nasofibrolaringoscopia para identificar el o los sitios de obstrucción. Además, se sabe que el 75% de los pacientes presentan obstrucciones en múltiples niveles y que, cuando el abordaje se hace multinivel, se logra corregir el SAHOS hasta en un 95%. Entre los procedimientos vigentes se encuentran cirugías de nariz, paladar blando, amígdalas, base de lengua, estimulación del nervio hipogloso y procedimientos del esqueleto facial, así como procedimientos coadyuvantes, entre los que están radiofrecuencia e implantes de paladar.

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.

Outcomes of Upper Airway Stimulation for Obstructive Sleep Apnea in a Multicenter German Postmarket Study

Objective Selective stimulation of the hypoglossal nerve is a new surgical therapy for obstructive sleep apnea, with proven efficacy in well-designed clinical trials. The aim of the study is to obtain additional safety and efficacy data on the use of selective upper airway stimulation during daily clinical routine. Study Design Prospective single-arm study. Setting Three tertiary hospitals in Germany (Munich, Mannheim, Lübeck). Subjects and Methods A multicenter prospective single-arm study under a common implant and follow-up protocol took place in 3 German centers (Mannheim, Munich, Lübeck). Every patient who received an implant of selective upper airway stimulation was included in this trial (apnea-hypopnea index ≥15/h and ≤65/h and body mass index <35 kg/m²). Before and 6 months after surgery, a 2-night home sleep test was performed. Data regarding the safety and efficacy were collected. Results From July 2014 through October 2015, 60 patients were included. Every subject reported improvement in sleep and daytime symptoms. The average usage time of the system was 42.9 ± 11.9 h/wk. The median apnea-hypopnea index was significantly reduced at 6 months from 28.6/h to 8.3/h. No patient required surgical revision of the implanted system. Conclusion Selective upper airway stimulation is a safe and effective therapy for patients with obstructive sleep apnea and represents a powerful option for its surgical treatment.