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.

[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.

Increased Body Mass Index Correlates with Less Favorable Postoperative Outcomes After Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea: A Retrospective Cohort Study.

OBJECTIVE: Obstructive sleep apnea is associated with high morbidity. Hypoglossal nerve stimulation (HNS) has become a novel (neuro-) surgical treatment strategy for obstructive sleep apnea, demonstrating good success rates. Beyond predefined inclusion and exclusion criteria, no precise data are available, enabling individual preoperative risk assessment. To improve preoperative risk stratification, this study analyzed individual patient factors that affect outcomes of HNS. METHODS: Fourteen patients treated with unilateral HNS were analyzed retrospectively. Assessed risk factors included: hypertension, diabetes mellitus, depression, smoking, alcohol consumption, body mass index (BMI), and disease duration. Treatment success was defined as a reduction in the postoperative apnea-hypopnea index (AHI) to ≤20 events/hour, with a relative reduction of at least 50% compared to baseline. RESULTS: A significant reduction in the postoperative apnea-hypopnea index was observed in all patients (P < 0.0001). BMI correlated significantly with postoperative AHI scores (95% confidence interval, 0.1519-0.8974; P = 0.018). Significant treatment success was observed in 50% of patients. Compared with the "Excellent Responder group," the "Responder group" demonstrated a significantly higher BMI (95% confidence interval, 1.174-6.226; P = 0.0078). Diabetes, hypertension, disease duration, smoking, depression, and alcohol consumption were not significantly associated with AHI reduction. CONCLUSIONS: Our findings suggest that BMI may be an independent risk factor for the response to HNS, with patients who had less benefit from therapy having significantly higher BMI than "Excellent Responders." Therefore, carefully selecting patients is crucial in obtaining optimal outcomes with HNS therapy, especially those with a high BMI.

Successful Reimplantation of Extruded Lead after Hypoglossal Nerve Stimulation Surgery.

Infection and extrusion of hardware are known complications of hypoglossal nerve stimulation surgery. We present a unique case of an extruded hardware lead successfully managed with reimplantation without need for explantation and new device placement. The topic will be discussed in context of the body of literature related to extruded medical device management. Laryngoscope, 133:2821-2822, 2023.

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

OBJECTIVE: To describe a novel lateral approach for hypoglossal nerve stimulator (HNS) implantation in women and provide evidence for its safety and efficacy. STUDY DESIGN: Retrospective case series. SETTING: Single academic medical center. METHODS: We identified patients implanted with HNS by a single surgeon from January 2017 to December 2021. Patient characteristics, postoperative complications, surgical duration, response to therapy, and need for revision surgery were recorded. RESULTS: One hundred four patients were included, including 93 males and 11 females. The lateral approach for HNS implantation involves placing the chest incision for the implantable pulse generator and respiratory sensor lead vertically in the anterior axillary line instead of horizontally in the infraclavicular area. No changes are made to the stimulator lead placement. All female patients were implanted using a lateral approach and all male patients were implanted via the standard anterior approach. Half of the patients were implanted via a 2-incision technique. The median surgical time duration was equivalent in male and female patients (119 [interquartile range (IQR): 105-138] vs 126 [IQR: 115-141], respectively). Revision was required in 2 (18%) females versus 6 (6%) males (p = .17). There were equivalent rates of therapy response as well as postoperative complications. CONCLUSION: A more cosmetic lateral approach is feasible for HNS in female patients and has a similar rate of adverse events and therapy responsiveness. Additional considerations in female patients include the ability to tolerate mammography as well as HNS implantation in the setting of existing breast implants.

Hypoglossal Nerve Stimulator Explantation Technique and Outcomes: A Retrospective Case Series.

INTRODUCTION: Upper airway stimulation via the hypoglossal nerve stimulator (HGNS) implant is a surgical method for treating obstructive sleep apnea. However, patients may need the implant removed for a variety of reasons. The purpose of this case series is to assess surgical experiences with HGNS explantation at our institution. We report on surgical approach, overall operative times, operative and postoperative complications, and discuss relevant patient-specific surgical findings when removing the HGNS. METHODS: We performed a retrospective case series of all patients that underwent HGNS implantation at a single tertiary medical center between January 9, 2021, and January 9, 2022. Subjects included adult patients who presented to the sleep surgery clinic of the senior author for surgical management of previously implanted HGNS. Patient clinical history was reviewed to determine the timing of the patient's implant, reasons for explant, and postoperative recovery course. Operative reports were reviewed to determine overall duration of surgery and any associated difficulties or deviations from the general approach. RESULTS: Between January 9, 2021, and January 9, 2022, 5 patients had an explantation of their HGNS implant. Explantation occurred between 8 and 63 months of their original implant surgery. The average operative time from incisional start time to close was 162 min for all cases with a range of 96-345 min. No significant complications were reported including pneumothorax and nerve palsy. CONCLUSION: This reported case series outlines the general steps for Inspire HGNS explantation as well as details the experiences in a case series of 5 subjects explanted over the year at a single institution. The results from the cases suggest that the explantation of the device can be performed efficiently and safely.

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.

The Posterior Belly of Digastric Muscle as the Landmark in Facial Nerve Anastomosis Surgery: Anatomical Study and Case Illustration.

OBJECTIVE: To establish a new method for fast exposure of the facial nerve and hypoglossal nerve during facial nerve anastomosis surgery. METHODS: Dissection of 12 formalin-fixed cadaveric specimens was performed to explore the positional relationship between the posterior belly of digastric muscle (PBD) and the facial nerve and hypoglossal nerve. We retrospectively reviewed patients who underwent facial nerve reconstruction surgery between 2015 and 2020 at Xuanwu Hospital, Capital Medical University, and the optimized surgical strategy based on the PBD was proposed. RESULTS: The trunk of the hypoglossal nerve runs across the external carotid artery after giving off the descendens hypoglossi located within the 1-cm scope deep to the junction of the tendon and belly of the PBD. The mean depth difference between the hypoglossal nerve and the junction of the tendon and belly of the PBD was 5.48 ± 2.24 mm (range, 1.88-9.27 mm). The stylomastoid foramen segment of the facial nerve was revealed after the parotid gland was dissected within the angle between the anterior margin of the mastoid tip and the inferior margin of the cartilage of the external acoustic meatus. CONCLUSIONS: The facial nerve and hypoglossal nerve can be rapidly identified using the PBD as an anatomical landmark. The end-to-end facial-descendens hypoglossi anastomosis is a reliable facial nerve reconstruction method for patients whose facial nerve was damaged during operation.

Microanatomic analyses of extratemporal facial nerve and its branches, hypoglossal nerve, sural nerve, and great auricular nerve.

OBJECTIVE: To investigate microanatomic organizations of the extratemporal facial nerve and its branches, hypoglossal nerve, sural nerve, and great auricular nerve. METHODS: Nerve samples were dissected in 12 postmortem autopsies, and histomorphometric analyses were conducted. RESULTS: There was no significant difference between the right and left sides of the nerve samples for the nerve area, fascicle area, number of fascicles and average number of axons. The lowest mean fascicle number was found in the hypoglossal nerve (4.9 ±â€¯1.4) while the highest was in great auricular nerve (11.4 ±â€¯6.8). The highest nerve area (3,182,788 ±â€¯838,430 µm2), fascicle area (1,573,181 ±â€¯457,331 µm2) and axon number (14,772 ±â€¯4402) were in hypoglossal nerve (p < 0.05). The number of axons per unit nerve area was higher in the facial nerve, truncus temporofacialis, truncus cervicofacialis and hypoglossal nerve, which are motor nerves, compared to the sural nerve and great auricular nerve, which are sensory nerves (p < 0.05). The number of axons per unit fascicle area was also higher in motor nerves than in sensory nerves (p < 0.05). CONCLUSION: In the present study, it was observed that each nerve contained a different number of fascicles and these fascicles were different both in size and in the number of axons they contained. All these variables could be the reason why the desired outcomes cannot always be achieved in nerve reconstruction.

Important aspect of hypoglossal nerve injury following gunshot wound; Can the clivus has a role? A case report.

Cranial nerve palsies after gunshot injury are not uncommon. We report the mechanism of isolated hypoglossal nerve paralysis caused by a gunshot. We report a 74 years old patient in whom a bullet entered through the right nostril and then ended up right occipital condyle. The only neurologic deficit was tongue deviation which resolved in one week. The bullet was not removed. The effect of clival slope may have an importance in this type of injury.

Predictors of favorable outcome following hypoglossal-to-facial nerve anastomosis for facial nerve palsy: a systematic review and patient-level analysis of a literature-based cohort.

OBJECTIVE: Facial nerve palsy is a debilitating condition that can arise from iatrogenic, traumatic, or congenital causes. One treatment to improve function of the facial muscles after facial nerve injury is hypoglossal-to-facial nerve anastomosis (HFA). HFA's efficacy and predictors of its success vary in the literature. Here, the authors present a patient-level analysis of a literature-based cohort to assess outcomes and investigate predictors of success for HFA. METHODS: Seven electronic databases were queried for studies providing baseline characteristics and outcomes of patients who underwent HFA. Postoperative outcomes were measured using the House-Brackmann (HB) grading scale. A change in HB grade of 3 points or more was classified as favorable. A cutoff value for time to anastomosis associated with a favorable outcome was determined using the Youden Index. RESULTS: Nineteen articles with 157 patients met the inclusion criteria. The mean follow-up length was 27.4 months, and the mean time to anastomosis after initial injury was 16 months. The end-to-side and end-to-end anastomosis techniques were performed on 84 and 48 patients, respectively. Of the 130 patients who had available preoperative and postoperative HB data, 60 (46.2%) had a favorable outcome. Time from initial injury to anastomosis was significantly different between patients with favorable and unfavorable outcomes (7.3 months vs 29.2 months, respectively; p < 0.001). The optimal cutoff for time to anastomosis to achieve a favorable outcome was 6.5 months (area under the curve 0.75). Patients who underwent anastomosis within 6.5 months of injury were more likely to achieve a favorable outcome (73% vs 31%, p < 0.001). CONCLUSIONS: HFA is an effective method for restoring facial nerve function. Favorable outcomes for facial nerve palsy may be more likely to occur when time to anastomosis is within a 6.5-month window.

Novel Outcome Analysis Tool for Hypoglossal Nerve Stimulator Sensor Lead Function and Comparison by Incision Type (2 Versus 3).

OBJECTIVE: No reported outcome measures have been established to evaluate sensor lead function in the hypoglossal nerve stimulator (HNS). This study describes the development of novel functional outcome measures for intraoperative sensor electrode function and compares 2-incision and 3-incision outcomes for HNS. METHODS: A retrospective cohort study of 100 consecutive patients who underwent HNS between June 2019 and September 2021. Demographic information, intraoperative findings, and immediate postoperative outcomes were recorded. Structured parameters were developed to compare intraoperative waveforms with six outcome measures utilized: waveform syncing, waveform amplitude, sensory current leakage, shark-fin morphology, cardiac artifact, and overall impression. Two sleep surgeons and two sleep medicine specialists compared all waveforms in a blinded fashion and assigned scores on the Likert Scale. RESULTS: The cohort included 50 three-incision and 50 two-incision patients. Age, gender, average body mass index, comorbidity profiles, and sleep endoscopy findings did not significantly differ between the two groups. No major complications occurred. The interclass-correlation-coefficient was greater than 0.7 for all comparisons (good to very good interrater reliability). There was no difference in waveform amplitude, cardiac artifact, sensory current leakage, or shark-fin morphology between the two groups. Waveform syncing and overall impression were statistically better in the 2-incision cohort. CONCLUSIONS: This study is the first to define a structured method of HNS sensor electrode outcome measurement and showed consistent measures by surgeons and sleep medicine specialists. This article supports the transition to the 2-incision technique among surgeons for placement of the sensor lead. Consideration should be given to utilizing this novel tool in the clinical/research setting and validating these measures moving forward. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:423-430, 2023.

Enhanced drug-induced sleep endoscopy: Distinguishing central from obstructive apnea.

This case report describes a patient originally diagnosed with obstructive sleep apnea (OSA) who was later found to have central sleep apnea (CSA) during drug-induced sleep endoscopy, which was subsequently confirmed on an in-laboratory sleep study. The revised diagnosis resulted in a change in recommended therapy from hypoglossal nerve stimulation to phrenic nerve stimulation. This case report is a reminder that the sleep surgeon must be cognizant of the possibility of CSA being misclassified as OSA especially as home sleep studies become increasingly routine, and discusses ways to more easily distinguish between CSA and OSA. Laryngoscope, 133:706-708, 2023.

Parental experience of hypoglossal nerve stimulator implantation in adolescents with Down Syndrome and obstructive sleep apnea.

PURPOSE: The purpose of this study is to explore the experience of parents in deciding whether to participate in a clinical trial of the insertion of the Hypoglossal Nerve Stimulator (HNS) to treat their adolescent with Down Syndrome (DS) and Obstructive Sleep Apnea (OSA). DESIGN AND METHODS: A qualitative descriptive design with interviews was used to gather parental experiences from those who consented to HNS for their adolescent with DS and OSA. Interviews were conducted, audiotaped, and transcribed. Basic content analysis was followed to interpret the data. Using a process of data debriefing/engagement, codes were generated, and field/reflective notes were used to assure trustworthiness of the data. RESULTS: Parents, 13 mothers/2 fathers, participated. Three themes were identified: Parents experience desperation about acceptance of standard of care for their adolescent with DS and OSA. This desperation led parents to seek information/insights from social media and they came to rely on those sites to explore options, ultimately leading them to HNS clinical trial. Finally, parents had a desire to share experience with HNS implantation. CONCLUSIONS: Parents described being desperate at acceptance of standards of care for OSA. They shifted reliance on experts and parents by searching social media pages to explore options for treatment of OSA. Parents wished to share experiences with the HNS implantation. PRACTICE IMPLICATIONS: Nurses play a role in preparing for the HNS by instructing/educating parents. Nurses can identify supportive social media sites for parents during the HNS decision and suggest ways to measure outcomes of HNS.

Interference With Implanted Upper Airway Stimulation Device by Phones With Magnet Technology.

Newer iPhone models with MagSafe magnetic technology can cause electromagnetic interference with the Inspire upper airway stimulator device (a surgical implant for the treatment of obstructive sleep apnea). Laryngoscope, 132:2513-2515, 2022.

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

OBJECTIVE: We investigated whether a palatal conversion procedure combined with a second-stage hypoglossal nerve stimulator (HGNS) insertion can be beneficial for those patients who have a complete concentric velopharyngeal collapse and may initially not meet the criteria for use of HGNS. METHODS: A retrospective chart review included all patients who underwent a planned multi-level sleep surgery including expansion sphincter pharyngoplasty (ESP) followed by HGNS. All patients had a complete concentric collapse (CCC) of the velopharynx (VP) on pre-intervention drug-induced sleep endoscopy (DISE) and were initially not a candidate for HGNS. These patients then underwent ESP followed by a DISE to confirm elimination of the CCC of the VP. They then went on to HGNS implantation several months later followed by a sleep study. RESULTS: A total of 20 patients were identified and included in the retrospective chart analysis. All patients who underwent ESP successfully converted their VP from CCC to an anterior-posterior collapse pattern and thus met inclusion criteria for HGNS. After the HGNS was implanted, patients showed a significant reduction of the mean AHI from 53.9 before ESP to 8.2 after ESP and HGNS and a decrease in the Epworth Sleep Score (ESS) from a mean of 13.3 to 5.7. CONCLUSION: ESP can be effective in eliminating the CCC of the VP thus making patients become HGNS candidates. In selected OSA patients, who have multilevel upper airway obstruction with complete concentric VP collapse, the combination of ESP and HGNS insertion should be considered as a planned 2-staged approach.

Muscle Fiber Composition Changes after Selective Nerve Innervation.

Facial nerve paralysis interferes with mimetic muscle function. To reconstruct natural facial movement, free muscle flaps are transplanted as new muscles. However, it is difficult to maintain resting tonus. A dual innervation technique in which other nerves such as the hypoglossal nerve or contralateral facial nerve are added is often applied. Using 10-week-old rats (n = 10), the masseteric and hypoglossal nerves were cut, and the distal stump of the masseteric nerve and the proximal stump of the hypoglossal nerve were then sutured (suture group). In the other group, the masseteric nerve was cut and cauterized (cut group). Immunohistochemistry and microarray were performed on the extracted masseter muscle. The immunohistochemistry results suggested that the muscles in the suture group obtained oxidative characteristics. The microarray showed the genes involved in mitochondrial function, including Perm1. In summary, our data support the validity of the dualinnervation technique for facial paralysis treatment.