Nerve fiber analysis of the lingual branch of the glossopharyngeal nerve in human adult subjects.

PURPOSE: Fibers of the glossopharyngeal part of the superior constrictor muscle are connected with fibers of the transverse lingual muscle, forming a ring of muscle at the base of the tongue. This group of muscles constrict the midpharyngeal cavity during retrusive movement of the tongue. The purpose of this study is to identify the contribution of the lingual branch of the glossopharyngeal nerve to the neuro-motor control of three muscles: the glossopharyngeal part of the superior pharyngeal constrictor muscle, the palatopharyngeal and the palatoglossus muscles. METHODS: Six en bloc samples (9 sides), including the tissue from the skull base to the hyoid bone were obtained from adult human cadavers. Nerve fiber of the lingual branch of the glossopharyngeal nerve (main root of the glossopharyngeal nerve) was examined by the use of a binocular stereomicroscope. RESULTS: We observed that, after branching to the stylopharyngeal muscle, the lingual branch of the glossopharyngeal nerve branched to the glossopharyngeal part of the superior pharyngeal constrictor muscle, the palatopharyngeal and the palatoglossus muscles before inserting into the space between the muscle layers of the superior and middle pharyngeal constrictors. CONCLUSION: These neuromuscular arrangements may suggest the presence of specialized constrictive movements of the midpharygeal cavity at the level of the base of the tongue with the retrusive movement of the tongue. The simultaneous contraction of the palatopharyngeal and palatoglossus muscles on the pharyngeal stage of deglutition may aid in the passage of bolus from the oral cavity to the midpharyngeal cavity by increasing pharyngeal pressure.

The pharyngeal plexus: an anatomical review for better understanding postoperative dysphagia.

The pharyngeal plexus is an essential anatomical structure, but the contributions from the glossopharyngeal and vagus nerves and the superior cervical ganglion that give rise to the pharyngeal plexus are not fully understood. The pharyngeal plexus is likely to be encountered during various anterior cervical surgical procedures of the neck such as anterior cervical discectomy and fusion. Therefore, a detailed understanding of its anatomy is essential for the surgeon who operates in and around this region. Although the pharyngeal plexus is an anatomical structure that is widely mentioned in literature and anatomy books, detailed descriptions of its structural nuances are scarce; therefore, we provide a comprehensive review that encompasses all the available data from this critical structure. We conducted a narrative review of the current literature using databases like PubMed, Embase, Ovid, and Cochrane. Information was gathered regarding the pharyngeal plexus to improve our understanding of its anatomy to elucidate its involvement in postoperative spine surgery complications such as dysphagia. The neural contributions of the cranial nerves IX, X, and superior sympathetic ganglion intertwine to form the pharyngeal plexus that can be injured during ACDF procedures. Factors like surgical retraction time, postoperative hematoma, surgical hardware materials, and profiles and smoking are related to postoperative dysphagia onset. Thorough anatomical knowledge and lateral approaches to ACDF are the best preventing measures.

Cricopharyngeal myotomy for delayed Cricopharyngeal dysfunction after head and neck surgery - case report.

BACKGROUND: Head and neck surgeries can perturb normal structures of neck muscles and nerve innervations, which are supposed to function in harmony to allow complicated process like swallowing. It is still likely that cricopharyngal dysfunction emerges years after the head and neck surgeries. CASE PRESENTATION: We report a case with history of left unilateral vocal cord immobility and development of dysphagia and aspiration 2 years after radical thyroidectomy with neck lymph nodes dissection and medialization thyroplasty. Cricopharyngeal dysfunction was impressed and was confirmed with visualization of cricopharyngeal narrowing segment in radiographic contrast swallow examination. The patient was treated successfully by cricopharyngeal myotomy, achieving long-term relief in our 4 years of follow up. CONCLUSIONS: Our case of delayed cricopharyngal dysfunction after radical thyroidectomy and medialization thyroplasty shows that it is important to follow up swallowing functions after patients with UVCI undergo medialization thyroplasty. In the event of delayed manifestation of cricopharyngeal function, it can still be treated successfully by cricoharyngeal myotomy, achieving long term relief of dysphagia.

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

PURPOSE: The aim of this study was to report on the successful application of upper airway stimulation (UAS) therapy in an adult Down syndrome (DS) patient with severe obstructive sleep apnea (OSA) and continuous positive airway pressure (CPAP) intolerance. METHODS: Baseline polysomnography (PSG) in a 23-year-old male OSA patient (body mass index (BMI) 24.4 kg/m2) revealed an apnea/hypopnea index (AHI) of 61.5 events/h and oxygen desaturation index (ODI) of 39.7 events/h. Based on the clinical examination, PSG and drug-induced sleep endoscopy, the patient fulfilled the formal inclusion criteria for UAS therapy: AHI between 15 and 65 events/h, BMI < 32 kg/m2, and no complete concentric collapse at the level of the velopharynx. RESULTS: Implantation of the hypoglossal nerve stimulator in the adult patient with DS resulted in a substantial subjective as well as objective improvement of OSA (63 to 81% decrease in AHI and 77% decrease in ODI), translating into an overall satisfactory outcome. CONCLUSION: Research on the long-term effectiveness of UAS therapy in a larger group of patients with DS is needed. However, based on the available literature and our presented case, respiration-synchronized electrostimulation of the hypoglossal nerve using UAS therapy may have a potential value in well-selected OSA patients with DS who are non-compliant to CPAP therapy.

Morphological Features of the Glossopharyngeal Nerve in the Peripharyngeal Space, the Oropharynx, and the Tongue.

The glossopharyngeal nerve comprises sensory, motor and parasympathetic fibers, and its problem results in several disorders. This study investigated the glossopharyngeal nerve to elucidate the characteristics of its extracranial course and branching pattern. The nerve and adjacent structures were gross anatomically examined in 32 cadavers. The glossopharyngeal nerve descended from the jugular foramen in the peripharyngeal space. It dodged between the carotid arteries and the internal jugular vein and distributed the carotid and pharyngeal branches that formed the plexus with the branches of the vagus and sympathetic nerves. The glossopharyngeal nerve curved anteriorly around the stylopharyngeus and supplied it and the glossopharyngeus. However, it occasionally disappeared because it penetrated the stylopharyngeus. The nerve passed medially to the stylohyoid ligament to enter the oropharynx, with its entry located medially to the facial artery. It appeared anteriorly to the stylopharyngeus and the palatopharyngeus and inferiorly to the palatine tonsil in the oropharynx. Its appearance was obscured beneath the tonsil and, sometimes, beneath the longitudinal muscles. The nerve distributed the branches to the palatine tonsil, which formed a plexus with those that pierced the glossopharyngeus from the outside. At the root of the tongue, the nerve ramified into the posterior branches to the epiglottic vallecula, the medial ones the lingual tonsil and the vallate papillae and the anterior ones the vallate and foliate papillae. This study suggests that, occasionally, the detection of the glossopharyngeal nerve is challenging, and its association with the pharyngeal muscles and the facial artery can facilitate its localization. Anat Rec, 302:630-638, 2019. © 2018 Wiley Periodicals, Inc.

[Progress of dopamine in obstructive sleep apnea hypopnea syndrome].

The etiology and pathogenesis of sleep obstructive apnea hypopnea syndrome (OSAHS) is not yet definitive, evidence shows that the dysfunction of pharyngeal nerve and the atonia of the muscle innervated by these nerve could play an important role in the progress of OSAHS. Dopamine is a neurotransmitter in the central nervous system which significantly affects the sleep-awake regulation. So far mounting evidence shows that dopamine has a potential role in the modulation of hypoglossal nucleus. The progress of dopamine in obstructive sleep apnea hypopnea syndrome is reviewed in this article.

Innervation of the human cricopharyngeal muscle by the recurrent laryngeal nerve and external branch of the superior laryngeal nerve.

PURPOSE: The major component of the upper esophageal sphincter is the cricopharyngeal muscle (CPM). We assessed the contribution of the laryngeal nerves to motor innervation of the CPM. METHODS: We performed an intraoperative electromyographic study of 27 patients. The recurrent laryngeal nerve (RLN), vagus nerve, external branch of the superior laryngeal nerve (EBSLN), and pharyngeal plexus (PP) were stimulated. Responses were evaluated by visual observation of CPM contractions and electromyographic examination via insertion of needle electrodes into the CPM. RESULTS: In total, 46 CPMs (24 right, 22 left) were evaluated. PP stimulation produced both positive visual contractions and electromyographic (EMG) responses in 42 CPMs (2080 ± 1583 µV). EBSLN stimulation produced visual contractions of 28 CPMs and positive EMG responses in 35 CPMs (686 ± 630 µV). Stimulation of 45 RLNs produced visible contractions of 37 CPMs and positive EMG activity in 41 CPMs (337 ± 280 µV). Stimulation of 42 vagal nerves resulted in visible contractions of 36 CPMs and positive EMG responses in 37 CPMs (292 ± 229 µV). Motor activity was noted in 32 CPMs by both RLN and EBSLN stimulation, 9 CPMs by RLN stimulation, and 3 CPMs by EBSLN stimulation; 2 CPMs exhibited no response. CONCLUSIONS: This is the first study to show that the EBSLN contributes to motor innervation of the human CPM. The RLN, EBSLN, or both of the nerves innervate the 90, 75, and 70 % of the CPMs ipsilaterally, respectively.

The functional role of the pharyngeal plexus in vocal cord innervation in humans.

Classical understanding of the function of the pharyngeal plexus in humans is that it relies on both motor branches for innervation of the majority of pharyngeal muscles and sensory branches for the pharyngeal wall sensation. To date there has been no reported data on the role of the pharyngeal plexus in vocal cord innervation. The aim of this study is to evaluate whether or not the plexus pharyngeus contributes to the innervation of the vocal cords. One hundred twenty-five sides from 79 patients (59 female, 20 male) undergoing thyroid surgery with intraoperative neuromonitoring were prospectively evaluated. While vocal cord function was evaluated with endotracheal tube surface electrodes, cricothyroid and cricopharyngeal muscle electromyographic recordings were obtained with a pair of needle electrodes. The ipsilateral pharyngeal plexus, external branch of the superior laryngeal nerve, and recurrent laryngeal nerve were stimulated with a monopolar probe at 1 mA. With stimulation of the plexus pharyngeus on 125 operated sides, positive electromyographic waveforms were detected from five ipsilateral vocal cords (accounting for 3.2% of all vocal cords monitored and 6.3% of patients). The mean EMG amplitude of the vocal cords with stimulation of the plexus pharyngeus was 147 ± 35.5 µV (range 110-203). In one case, the long latency time of 19.8 ms correlated with innervation by the glottic closure reflex pathway. The short latencies seen in the other four cases [3.9 ± 1.1 ms (range 3.2-5.5)] correlated with direct innervation. In some cases, the plexus pharyngeus may contribute to vocal cord innervation by reflex or direct innervation patterns in humans.

Upper Airway Stimulation Therapy.

Traditional upper airway surgery directly modifies skeletal and soft tissue structures surrounding the airway to treat obstructive sleep apnea (OSA). Upper airway stimulation (UAS) attempts to treat upper airway obstruction and OSA by stimulating the hypoglossal nerve. The Inspire II implant has been approved for clinical UAS. Basic science data support that UAS prevents obstruction and improves airflow. Clinical results demonstrate that UAS improves respiratory sleep metrics and improves both objective and subjective self-reported sleep and quality-of-life outcomes. In a substantial number of individuals who meet inclusion criteria, UAS appears to be a viable, long-term, low-morbidity treatment of moderate-to-severe OSA.

A scalable method for automatically measuring pharyngeal pumping in C. elegans.

BACKGROUND: The nematode Caenorhabditis elegans is widely used for studying small neural circuits underlying behavior. In particular, the rhythmic feeding motions collectively termed pharyngeal pumping are regulated by a nearly autonomous network of 20 neurons of 14 types. Despite much progress achieved through laser ablation, genetics, electrophysiology, and optogenetics, key questions regarding the regulation of pumping remain open. NEW METHOD: We describe the implementation and application of a scalable automated method for measuring pumping in controlled environments. Our implementation is affordable and flexible: key hardware and software elements can be modified to accommodate different requirements. RESULTS: We demonstrate prolonged measurements under controlled conditions and the resulting high quality data. We show the scalability of our method, enabling high throughput, and its suitability for maintaining static and dynamic conditions. When food availability was oscillated, pumping rates were low as compared to steady conditions and pumping activity was not reliably modulated in response to changes in food concentration. COMPARISON WITH EXISTING METHOD: The prevailing method for measuring rates of pumping relies on scoring by visual inspection of short recordings. Our automated method compares well with manual scoring. It enables detailed statistical characterization under experimental conditions not previously accessible and minimizes unintentional bias. CONCLUSIONS: Our approach adds a powerful tool for studying pharyngeal pumping. It enhances the experimental versatility of assaying genetic and pharmacological manipulations and the ability to characterize the resulting behavior. Both the experimental setup and the analysis can be readily adapted to additional challenging motion detection problems.

Differential effects of respiratory and electrical stimulation-induced dilator muscle contraction on mechanical properties of the pharynx in the pig.

Respiratory stimulation (RS) during sleep often fails to discontinue flow limitation, whereas electrical stimulation (ES) of the hypoglossus (HG) nerve frequently prevents obstruction. The present work compares the effects of RS and HG-ES on pharyngeal mechanics and the relative contribution of tongue muscles and thoracic forces to pharyngeal patency. We determined the pressure-area relationship of the collapsible segment of the pharynx in anesthetized pigs under the following three conditions: baseline (BL), RS induced by partial obstruction of the tracheostomy tube, and HG-ES. Parameters were obtained also after transection of the neck muscles and the trachea (NMT) and after additional bilateral HG transection (HGT). In addition, we measured the force produced by in situ isolated geniohyoid (GH) during RS and HG-ES. Intense RS was recognized by large negative intrathoracic pressures and triggered high phasic genioglossus and GH EMG activity. GH contraction produced during maximal RS less than a quarter of the force obtained during HG-ES. The major finding of the study was that RS and ES differed in the mechanism by which they stabilized the pharynx: RS lowered the pressure-area slope, i.e., reduced pharyngeal compliance (14.1 ± 2.9 to 9.2 ± 1.9 mm(2)/cmH2O, P < 0.01). HG-ES shifted the slope toward lower pressures, i.e., lowered the calculated extraluminal pressure (17.4 ± 5.8 to 9.2 ± 7.4 cmH2O, P < 0.01). Changes during RS and HG-ES were not affected by NMT, but the effect of RS decreased significantly after HGT. In conclusion, HG-ES and RS affect the pharyngeal site of collapse differently. Tongue muscle contraction contributes to pharyngeal stiffening during RS.

Peripheral component of laryngeal and pharyngeal motor evoked potentials.

In this study, the responses of thyroarytenoid (TA) and cricopharyngeus (CP) muscles were simultaneously recorded to peripheral magnetic stimulation of the vagus nerve. Recordings were performed in 13 subjects by means of concentric needle EMG electrodes inserted in the TA and CP. Magnetic shocks were delivered to the vagus nerve with a round coil placed occipitally, while EMG was silent in the TA. In all subjects, clear-cut responses were obtained simultaneously in both muscles. In TA compared to CP, the maximum amplitude of the responses were higher, whereas the onset latency was shorter. Our results revealed that simultaneous recordings of TA and CP motor responses to occipital magnetic stimulation enabled a reliable evaluation of their peripheral innervation by the vagus nerve.

Distinct Mechanisms Underlie Quiescence during Two Caenorhabditis elegans Sleep-Like States.

Electrophysiological recordings have enabled identification of physiologically distinct yet behaviorally similar states of mammalian sleep. In contrast, sleep in nonmammals has generally been identified behaviorally and therefore regarded as a physiologically uniform state characterized by quiescence of feeding and locomotion, reduced responsiveness, and rapid reversibility. The nematode Caenorhabditis elegans displays sleep-like quiescent behavior under two conditions: developmentally timed quiescence (DTQ) occurs during larval transitions, and stress-induced quiescence (SIQ) occurs in response to exposure to cellular stressors. Behaviorally, DTQ and SIQ appear identical. Here, we use optogenetic manipulations of neuronal and muscular activity, pharmacology, and genetic perturbations to uncover circuit and molecular mechanisms of DTQ and SIQ. We find that locomotion quiescence induced by DTQ- and SIQ-associated neuropeptides occurs via their action on the nervous system, although their neuronal target(s) and/or molecular mechanisms likely differ. Feeding quiescence during DTQ results from a loss of pharyngeal muscle excitability, whereas feeding quiescence during SIQ results from a loss of excitability in the nervous system. Together these results indicate that, as in mammals, quiescence is subserved by different mechanisms during distinct sleep-like states in C. elegans.

Pharyngeal Motor Evoked Potential Monitoring During Skull Base Surgery Predicts Postoperative Recovery from Swallowing Dysfunction.

OBJECTIVE: Monitoring pharyngeal motor evoked potential (PhMEP) with a modified endotracheal tube is useful for predicting postoperative swallowing dysfunction. However, the relationship between intraoperative PhMEP findings and recovery from postoperative swallowing dysfunction has not been clarified. The aim of this study was to determine whether PhMEP monitoring predicts swallowing dysfunction not only immediately after surgery but also in the postoperative recovery period. METHODS: We analyzed PhMEPs in 36 patients during treatment for skull base tumors. Recovery from postoperative swallowing dysfunction was evaluated when oral intake was started postsurgery and drip or tube feeding was discontinued. The correlation between the final to baseline PhMEP ratio and postoperative recovery times from swallowing dysfunction was examined. RESULTS: The PhMEP ratio significantly correlated with postoperative swallowing function immediately after surgery (P < 0.001). The period before starting oral intake in patients with a PhMEP ratio >50% (mean ± standard deviation [SD], 3.8 ± 4.3 days) was shorter than those with a PhMEP ratio ≤50% (mean ± SD, 14.7 ± 11.8 days; P < 0.01). Drip or tube feeding was removed from patients with a PhMEP ratio >50% significantly earlier (mean ± SD, 13.7 ± 19.2 days) than those with a PhMEP ratio ≤50% (mean ± SD, 38.3 ± 27.3 days; P < 0.05). Both univariate and multivariate analysis showed that only the PhMEP ratio was predictive of early recovery from swallowing dysfunction. CONCLUSIONS: PhMEP monitoring allowed us to predict not only immediate swallowing dysfunction but also recovery from the dysfunction in the postsurgery period.

Blood supply of the terminal part of the external branch of the superior laryngeal nerve.

PURPOSE: The external laryngeal nerve (ELN) carries motor fibers to the cricothyroid and inferior pharyngeal muscles. Damage to the nerve may cause symptoms such as a monotone voice. One reason for these symptoms may be nerve injury due to inadvertent stretching, ligation or transaction of the nerve during the dissection of the superior pole of the thyroid gland. We hypothesized a new reason for the symptoms, an insufficient arterial blood supply to the nerve, and investigated this hypothesis. METHODS: From 36 larynges, 52 sides (26 right and 26 left) were dissected under a surgical Zeiss-OpM1 microscope. RESULTS: The arterial branch to the external branch of the superior laryngeal nerve originated from the posterior glandular branch of the superior thyroid artery in 26 (50%) sides, from the anterior glandular branch in 23 (44.23%) sides, from its trunk on one (1.92%) side, from the infrahyoid branch on one (1.92%) side and from the bifurcation of the superior thyroid artery at the level of separation of the anterior and posterior glandular branches on one (1.92%) side. CONCLUSION: Devascularization of the ELN may lead to dysfunction, so this nerve's varied blood supply should be kept in mind when invasive procedures are performed in this region.

Short-term potentiation in the control of pharyngeal muscles in obstructive apnea patients.

STUDY OBJECTIVES: To determine if activation of the genioglossus (GG) muscle during obstructive apnea events involves short-term potentiation (STP) and is followed by sustained activation beyond the obstructive phase (after-discharge). DESIGN: Physiological study. SETTING: Sleep laboratory in a tertiary hospital. PARTICIPANTS: Twenty-one patients with obstructive apnea. INTERVENTIONS: Polysomnography on continuous positive airway pressure (CPAP) with measurement of genioglossus activity. Brief dial-downs of CPAP to induce obstructive events. MEASUREMENTS AND RESULTS: Peak, phasic, and tonic genioglossus activities were measured breath-by-breath before, during, and following three-breath obstructions. Tonic but not phasic activity increased immediately following the first obstructed breath (4.9 ± 1.6 versus 3.6 ± 1.2 %GGMAX; P = 0.01) under conditions where stimuli to genioglossus activation were likely constant, strongly implicating STP in mediating recruitment of tonic activity. Both phasic and tonic activities declined slowly after relief of obstruction (after-discharge). Decay time constants were systematically shorter for phasic than for tonic activity (7.5 ± 3.8 versus 18.1 ± 8.4 sec; P < 0.001). Decay time-constant of peak activity correlated with tonic, but not phasic, recruitment. Cortical arousal near the end of obstruction resulted in a lower after-discharge (P < 0.01). Contribution of tonic activity to the increase in peak activity (6-65%Peak), as well as the decay constant (6-30 sec), varied considerably among patients. CONCLUSIONS: Short-term potentiation contributes to recruitment of the genioglossus during obstructive episodes and results in sustained tonic activity beyond the obstructive phase, thereby potentially preventing recurrence of obstruction. Wide response differences among subjects suggest that this mechanism may contribute to severity of the disorder. The after-discharge is inhibited following cortical arousal, potentially explaining arousals' destabilizing effect.

Identification of a pharmacological target for genioglossus reactivation throughout sleep.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is a significant public health problem caused by repeated episodes of upper airway closure that occur only during sleep. Attempts to treat OSA pharmacologically have been unsuccessful because there has not been identification of a target operating at cranial motor nuclei, blockade of which can reactivate pharyngeal muscle activity throughout sleep. Increasing potassium conductance is a common mechanism by which state-dependent neuromodulators reduce motoneuron excitability. Therefore, we aimed to determine if potassium channel blockade is an effective strategy to reactivate the pharyngeal musculature throughout sleep. DESIGN PARTICIPANTS AND INTERVENTIONS: In rats chronically instrumented for recording sleep-wake states and respiratory motor activities, we locally microperfused pharmacological agents into the hypoglossal motor pool to modulate potassium channels of three major classes: inwardly rectifying, two-pore domain, and voltage-gated. MEASUREMENTS AND RESULTS: Microperfusion of the inwardly rectifying potassium channel blocker, barium, as well as the voltage-gated potassium channel blockers, tetraethylammonium and 4-aminopyridine, increased tonic and respiratory-related genioglossus activities throughout nonrapid eye movement (non-REM) and rapid eye movement (REM) sleep to 133-300% of levels present during baseline wakefulness. In contrast, microperfusion of methanandamide (TWIK-related acid-sensitive potassium [TASK] channel blocker/cannabinoid receptor agonist) activated genioglossus in wakefulness but not in sleep. CONCLUSIONS: These findings establish proof-of-principle that targeted blockade of certain potassium channels at the hypoglossal motor pool is an effective strategy for reversing upper airway hypotonia and causing sustained reactivation of genioglossus throughout nonrapid eye movement and rapid eye movement sleep. These findings identify an important new direction for translational approaches to the pharmacological treatment of obstructive sleep apnea.

Upper-airway stimulation for obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea is associated with considerable health risks. Although continuous positive airway pressure (CPAP) can mitigate these risks, effectiveness can be reduced by inadequate adherence to treatment. We evaluated the clinical safety and effectiveness of upper-airway stimulation at 12 months for the treatment of moderate-to-severe obstructive sleep apnea. METHODS: Using a multicenter, prospective, single-group, cohort design, we surgically implanted an upper-airway stimulation device in patients with obstructive sleep apnea who had difficulty either accepting or adhering to CPAP therapy. The primary outcome measures were the apnea-hypopnea index (AHI; the number of apnea or hypopnea events per hour, with a score of ≥15 indicating moderate-to-severe apnea) and the oxygen desaturation index (ODI; the number of times per hour of sleep that the blood oxygen level drops by ≥4 percentage points from baseline). Secondary outcome measures were the Epworth Sleepiness Scale, the Functional Outcomes of Sleep Questionnaire (FOSQ), and the percentage of sleep time with the oxygen saturation less than 90%. Consecutive participants with a response were included in a randomized, controlled therapy-withdrawal trial. RESULTS: The study included 126 participants; 83% were men. The mean age was 54.5 years, and the mean body-mass index (the weight in kilograms divided by the square of the height in meters) was 28.4. The median AHI score at 12 months decreased 68%, from 29.3 events per hour to 9.0 events per hour (P<0.001); the ODI score decreased 70%, from 25.4 events per hour to 7.4 events per hour (P<0.001). Secondary outcome measures showed a reduction in the effects of sleep apnea and improved quality of life. In the randomized phase, the mean AHI score did not differ significantly from the 12-month score in the nonrandomized phase among the 23 participants in the therapy-maintenance group (8.9 and 7.2 events per hour, respectively); the AHI score was significantly higher (indicating more severe apnea) among the 23 participants in the therapy-withdrawal group (25.8 vs. 7.6 events per hour, P<0.001). The ODI results followed a similar pattern. The rate of procedure-related serious adverse events was less than 2%. CONCLUSIONS: In this uncontrolled cohort study, upper-airway stimulation led to significant improvements in objective and subjective measurements of the severity of obstructive sleep apnea. (Funded by Inspire Medical Systems; STAR ClinicalTrials.gov number, NCT01161420.).

Effects of pharyngeal water stimulation on swallowing behaviors in healthy humans.

The aims of the present study were to determine whether the interval between swallows and the electromyographic (EMG) burst patterns of the suprahyoid muscles is affected by peripheral inputs during swallowing. Eighteen normal adults were asked to perform repetitive voluntary swallowing as quickly as possible, and three variables of swallowing were measured and evaluated, i.e., the swallowing intervals and the time interval between the onset and peak (rising time) and between the peak and offset (falling time) of the suprahyoid EMG burst. During recording, pharyngeal fluid infusion was applied with distilled water or 0.3 M NaCl solution at a very slow infusion rate (0.2 mL/min). The former and latter were used to activate and inhibit the excitation of water-sensitive receptors in the pharynx, respectively. The swallowing interval was significantly shorter during infusion of water than during infusion of NaCl solution. The rising time was also significantly shorter during infusion of water than during infusion of NaCl solution. There was a linear positive correlation between these values and facilitatory effects: the longer either the swallowing interval or rising time with infusion of 0.3 M NaCl solution, the stronger the facilitation of swallowing by the activation of water receptors. Facilitatory effects on the swallowing interval and rising time showed a linear correlation. It is suggested that weak liquid stimulation changed sensory inputs into the swallowing center and synchronously modulated the swallowing interval and time interval between the onset and peak of the EMG burst.

[A patient with Fisher syndrome and pharyngeal-cervical-brachial variant of Guillain-Barré syndrome having a complication of SIADH].

A 69-year-old woman complained of diplopia and truncal titubation after upper respiratory infection. She presented with mydriasis and external opthalmoplegia of bilateral eyes, ataxia, hyporeflexia and cervical-brachial muscle weakness. The protein abnormally increased (49 mg/dl) in the cerebrospinal fluid, and the serum anti-GQ1b and anti-GT1a IgG antibodies were positive. The blood sodium level was 128 mmol/l indicating hyponatremia. She had low plasma osmolarity (251 mOsm/kg), high urine osmolarity (357 mOsm/kg) and high urine sodium level (129 mmol/l), while the blood level of antidiuretic hormone was not able to be measured. She was diagnosed to have Fisher syndrome (FS), pharyngeal-cervical-brachial variant of Guillain-Barré syndrome (PCB) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The hyponatremia improved with hyperosmotic saline infusion and restriction of water intake. Intravenous immunoglobulin therapy (IVIg) was effective only for ataxia, but the other symptoms mostly remained unchanged for a month. The serum anti-GQ1b IgG antibody was still positive even after one month. We performed high-dose intravenous steroid-pulse therapy. Then the mydriasis, external opthalmoplegia and cervical-brachial muscle weakness were immediately improved. This was a rare case of FS and PCB complicated with SIADH. IVIg, not steroid therapy, is generally chosen for FS since FS is considered as a variant of Guillain-Barré syndrome and steroid is not effective for Guillain-Barré syndrome as was proven by double-blind study. We suppose that the combined therapy of IVIg and steroid would be effective in patients with complicated symptoms and multiple antibodies.