Laryngeal Stimulation Research Articles

Neuromuscular electrophonopedic stimulation of the larynx after surgical treatment of patients with differentiated thyroid cancer

BACKGROUND: Thyroid cancer is the most common endocrine malignancy, accounting for 3.4% of all cancers diagnosed annually. Differentiated thyroid cancer (DTC) is primarily treated with surgery, which can often involve complications such as postoperative pareses or reversible laryngeal nerve (RLN) paralysis. Currently, rehabilitation possibilities for patients with postoperative RLN pairs are relevant. In this study, we used neuromuscular electrostimulation with vocaSTIM in combination with drug therapy and evaluated the effectiveness of the rehabilitation. AIMS: To determine the possibility of using neuromuscular electrophonopathic laryngeal stimulation (NMELS) in restoring laryngeal function after surgical treatment of DTC complicated by pareses/paralysis of thr RLN. MATERIALS AND METHODS: Seventy-six patients with DTC who have undergone surgical treatment, complicated by paresis of RLN, were enrolled in this study. RESULTS: The study analyzed the treatment results of these 76 patients. The age of the patients ranged from 6 to 78 (average age, 47) years, the female-to-male ratio was 59 to 17 (women, 77.6%; men, 22.4%). Postoperative unilateral laryngeal paresis was present in 56 patients (73.68%) and bilateral lesions in 20 (26.32%). Phonation violation was found in all patients: dysphonia, 76 (100%); dysphagia, 28 (36.84%); and respiratory failure, 11 (14.47%), and 2 patients (2.63%) were tracheotomized postoperatively. All patients underwent neuro-phonic rehabilitation with mandatory assessment and video fixation of laryngeal function. As a result of neuromuscular electrophonopathic stimulation of the larynx, 69 out of 76 patients (90.79%) had improved larynx function. CONCLUSIONS: Based on our experience, NMELS with vocaSTIM can be used for restoring the functions of the larynx in patients with RLN paresis of varying severities, after surgical treatment for DTC.

Dexmedetomidine decreases stress post-operative in pediatrics

ABSTRACT Introduction Tracheal extubation causes hypertension and tachycardia. These associated hemodynamic changes are due to sympathetic discharge due to epipharyngeal and laryngeal stimulation.(1) Aim of work Dexmedetomidine is an effective sedative and analgesic agent, it helps in opioid sparing and multimodal techniques in pediatric anesthesia and reduces the toxicity of common anesthetics, and it has been approved by the end of 1999 by the FDA for human use for sedation in the intensive care unit (ICU). Dexmedetomidine is notable for its ability to provide sedation without risk of respiratory depression and can provide cooperative or arousable sedation. The aim of this study is to assess the effect of administering dexmedetomidine near the end of surgery versus a control group regarding the change in circulatory reflexes (represented by MAP) and the incidence of adverse events such as cough, laryngeal spasm or desaturation. Study design This study was designed as a prospective randomized controlled study. It was conducted in the Pediatrics orthopedic surgery theatre (Abo El Reesh pediatric Hospital) belonging to Cairo university hospitals on 70 patients divided into two groups 35 patients each and aged from 3–12 years planned for elective isolated limb anomaly correction. Result Dexmedetomidine injection near the end of the operation decreased the stress induced during extubation with almost no change in HR or MAP and less cough score, which indicated smoother extubation. Conclusion Dexmedetomidine is a potent alpha 2 receptor agonist, having analgesic and sedative effects and sparing usage of opioids without compromising respiratory reflexes or attenuating cardiovascular response during extubation.

The Feasibility of Home-Based Treatment Using Vibratory Stimulation in Chronic Severe Dysphagia.

Previously, externally placed vibratory laryngeal stimulation increased rates of swallowing in persons with and without dysphagia. This study examined the feasibility of using a vibratory device on the skin over the thyroid cartilage for home-based swallowing rehabilitation in long-standing dysphagia. Only participants with long-standing dysphagia (> 6 months) following cerebrovascular accident or head/neck cancer who had not previously benefited from dysphagia therapy participated. The device had two modes used daily for 90 days. In automatic mode, participants wore the device when awake, which vibrated for 4-8 s every 5 min to trigger a volitional swallow. In manual mode, participants practiced by activating vibration while swallowing rapidly. Study-related adverse events, such as pneumonia, and device-recorded adherence were tracked. Swallowing function on a modified barium swallow study was assessed at baseline and after 3 months of device use. Outcome measures included the Dysphagia Outcome and Severity Scale (DOSS), Penetration-Aspiration Scale (PAS), and swallowing timing measures. Participants' perceptions of the vibratory device and training were obtained. The intent to treat analysis showed seven of 11 participants completed the study, all with severe chronic dysphagia. Of those seven participants completing the study, two developed respiratory complications (possibly due to pneumonia) that cleared after antibiotic intervention. For prescribed practice trials, adherence was 80% or greater in four of seven participants (57%) whereas prescribed automatic stimulations were met in only two of seven participants (29%). Three participants (43%) had a modest benefit on DOSS. The time to vestibule closure after the bolus passed the ramus was reduced in five participants (71%) on the modified barium swallow study. Overall, the results have indicated that intensive home-based practice with stimulation may provide limited functional benefits in severe chronic dysphagia. https://doi.org/10.23641/asha.21498591.

Extreme bradycardia during microsurgery of the larynx

Introduction: Successful anesthetic management of microlaryngeal cases requires a high degree of cooperation with the surgeon, a reciprocal understanding of the potential problems, and adequate preparation on both sides to meet the anticipated challenges that may arise. Case description: A 55-year-old male patient (weight 104 kg, height 176 cm), ASA III, was admitted to our hospital for microlaryngeal surgery because of tumor formation of the larynx. The preoperative evaluation revealed no significant personal or family history for adverse reaction to anesthetics. A general anesthesia was scheduled for this patient. Fentanyl 0.3 mg, atropine 0.5 mg, propofol 220 mg and succinylcholine 130 mg were administered for anesthesia induction. After intubation 2.5% sevoflurane was used for anesthesia maintenance. After endotracheal intubation was performed surgeon tried to put on the tube of Kleinsasser. During this procedure the heart rate of the patient extremely dropped from 85 to 25 beats per minute. Discussion: Performance of conventional and operative direct laryngoscopy, supraglottic tissue distention, and laryngeal stimulation elicit intense cardiovascular responses, resulting in tachycardia, arterial and pulmonary hypertension, and arrhythmias. Although these responses are usually short lived, myocardial ischemia and compromise of cerebral circulation may occur in high-risk patients, resulting in adverse outcomes. Conclusion: There is a risk of severe bradycardia after putting on the tube of Kleinsasser during microlaryngeal surgery, which can cause hemodynamic

Neurons that Project to both the Nucleus Ambiguus and the Bӧtzinger Complex are Ideally Situated to control Laryngeal Adduction and Apnoea During Swallowing

Laryngeal stimulation that generates swallow activity is accompanied by laryngeal adduction along with central shutdown of breathing (apnoea) to execute safe swallowing without aspiration. The neural control of this is poorly understood. We hypothesized that the temporal precision of these separate phenomenon i.e., laryngeal adduction and apnoea during swallow is controlled by swallow burst generating neurons in the nucleus tractus solitarius (NTS) that project simultaneously to the caudal nucleus ambiguus (NA) for laryngeal adductions and to the Bӧtzinger complex (BötC) for apnoea. The present study aimed to provide anatomical support for the existence of such dual projecting neurons in the NTS. Retrograde tracing experiments were performed on adult male anaesthetised Sprague Dawley rats (n=2). Each rat received two microinjections of a retrograde tracer: cholera toxin B-fluorescent conjugate (CTB-555) into the BötC and unconjugated CTB into the NA. Following a recovery period of 5-6 days the rats were euthanased and perfused transcardially with 4% paraformaldehyde with immunohistochemistry performed to visualize those neurons traced by the unconjugated CTB. The rostral to caudal distribution of labelled neurons in the NTS was determined by analysing multichannel tile images with fluorescent microscopy. Among the single labelled neurons in the caudal NTS a small number of double-labelled neurons were identified. The double-labelled neurons were found caudal to obex with ≤ 25 per section (n=2). This study supports the existence of neurons in the caudal NTS with simultaneous projection to NA and BötC and which could be potential candidates for the control of laryngeal adduction and apnoea during swallowing.

Assessment of efficacy of intravenous fentanyl citrate for attenuation of hemodynamic responses during laryngoscopy and endotracheal intubation

Introduction: Laryngoscopy and intubation result in stimulation of larynx, pharynx, epipharynx and trachea, which are extensively innervated by autonomic nervous system. The parasympathetic supply is via the vagus and sympathetic supply via superior cervical ganglion. To diminish hemodynamic responses to tracheal intubation, Fentanyl along with hypnotic agents commonly used. Keeping in mind, an attempt has been made to assess the efficacy of injection fentanyl for attenuation of sympathetic response to intubation. Aims and objective: To assess efficacy of 2microgram/kg body weight fentanyl and 3 microgram/kg body weight fentanyl administered before laryngoscopy and endotracheal intubation for attenuation of hemodynamicresponse. Materials and Methods: 90 normotensive adult patients, belonging to ASA physical status I, of either sex, age group of 18-65 years, free from inter current cardiovascular and neurological disease, were posted for elective surgical procedures under general anaesthesia requiring orotracheal intubation were selected. All were elective cases. Three groups were made. Group I-Control group-10 cc normal saline IV. Group II- 2microgram/kg body weight fentanyl IV diluted to 10 cc with Distillate Water (DW). Group III- 3 microgram/kg body weight fentanyl IV diluted to 10 cc with D.W. Each group comprised of 30 patients. Result: The rise in pulse rate in both the fentanyl groups, was less and statistically significant than control group (p Conclusion: Use of intravenous fentanyl in both doses, i.e. 2 mcg/kg as well as 3 mcg/kg is safe and effective for attenuation of hemodynamic response to laryngoscopy and intubation. Keywords: Fentanyl, Intubation, Laryngoscopy, Hemodynamic.

Descending Modulation of Laryngeal Vagal Sensory Processing in the Brainstem Orchestrated by the Submedius Thalamic Nucleus.

The nodose and jugular vagal ganglia supply sensory innervation to the airways and lungs. Jugular vagal airway sensory neurons wire into a brainstem circuit with ascending projections into the submedius thalamic nucleus (SubM) and ventrolateral orbital cortex (VLO), regions known to regulate the endogenous analgesia system. Here we investigate whether the SubM-VLO circuit exerts descending regulation over airway vagal reflexes in male and female rats using a range of neuroanatomical tracing, reflex physiology, and chemogenetic techniques. Anterograde and retrograde neuroanatomical tracing confirmed the connectivity of the SubM and VLO. Laryngeal stimulation in anesthetized rats reduced respiration, a reflex that was potently inhibited by activation of SubM. Conversely, inhibition of SubM potentiated laryngeal reflex responses, while prior lesions of VLO abolished the effects of SubM stimulation. In conscious rats, selective chemogenetic activation of SubM neurons specifically projecting to VLO significantly inhibited respiratory responses evoked by inhalation of the nociceptor stimulant capsaicin. Jugular vagal inputs to SubM via the medullary paratrigeminal nucleus were confirmed using anterograde transsynaptic conditional herpes viral tracing. Respiratory responses evoked by microinjections of capsaicin into the paratrigeminal nucleus were significantly attenuated by SubM stimulation, whereas those evoked via the nucleus of the solitary tract were unaltered. These data suggest that jugular vagal sensory pathways input to a nociceptive thalamocortical circuit capable of regulating jugular sensory processing in the medulla. This circuit organization suggests an intersection between vagal sensory pathways and the endogenous analgesia system, potentially important for understanding vagal sensory processing in health and mechanisms of hypersensitivity in disease.SIGNIFICANCE STATEMENT Jugular vagal sensory pathways are increasingly recognized for their important role in defensive respiratory responses evoked from the airways. Jugular ganglia neurons wire into a central circuit that is notable for overlapping with somatosensory processing networks in the brain rather than the viscerosensory circuits in receipt of inputs from the nodose vagal ganglia. Here we demonstrate a novel and functionally relevant example of intersection between vagal and somatosensory processing in the brain. The findings of the study offer new insights into interactions between vagal and spinal sensory processing, including the medullary targets of the endogenous analgesia system, and offer new insights into the central processes involved in airway defense in health and disease.

Methods of surgical treatment of bilateral vocal fold paralysis.

Bilateral vocal fold paralysis presents as their complete or partial immobilisation. The median or paramedian position of vocal folds contributes to the narrowing of the airway at the level of the glottis and manifests as inspiratory dyspnoea. For many years iatrogenic injury of recurrent laryngeal nerves during thyroidectomy has been viewed as the most common underlying reason. It is very often a lifethreatening condition requiring not only corticosteroid administration and intubation, which only constitute a short-term symptomatic therapy, but also surgical intervention, including tracheostomy. The most common surgical methods implemented in bilateral vocal fold paralysis include posterior cordectomy, arytenoidectomy, and, more and more commonly, re-innervation. Other techniques used in restoring airway patency include laterofixation, botulinum toxin injection, and laryngeal stimulation, which is still under research. Stem cell and gene therapy are also being researched. Notably, the main purpose of surgical treatment is the provision of airway patency with the preservation of the phonatory and protective functions of the larynx.

Assessment of Common Criteria for Awake Extubation in Infants and Young Children.

Practice patterns surrounding awake extubation of pediatric surgical patients remain largely undocumented. This study assessed the value of commonly used predictors of fitness for extubation to determine which were most salient in predicting successful extubation following emergence from general anesthesia with a volatile anesthetic in young children. This prospective, observational study was performed in 600 children from 0 to 7 yr of age. The presence or absence of nine commonly used extubation criteria in children were recorded at the time of extubation including: facial grimace, eye opening, low end-tidal anesthetic concentration, spontaneous tidal volume greater than 5 ml/kg, conjugate gaze, purposeful movement, movement other than coughing, laryngeal stimulation test, and oxygen saturation. Extubations were graded as Successful, Intervention Required, or Major Intervention Required using a standard set of criteria. The Intervention Required and Major Intervention Required outcomes were combined as a single outcome for analysis of predictors of success. Successful extubation occurred in 92.7% (556 of 600) of cases. Facial grimace odds ratio, 1.93 (95% CI, 1.03 to 3.60; P = 0.039), purposeful movement odds ratio, 2.42 (95% CI, 1.14 to 5.12; P = 0.022), conjugate gaze odds ratio, 2.10 (95% CI, 1.14 to 4.01; P = 0.031), eye opening odds ratio, 4.44 (95% CI, 1.06 to 18.64; P= 0.042), and tidal volume greater than 5 ml/kg odds ratio, 2.66 (95% CI, 1.21 to 5.86; P = 0.015) were univariately associated with the Successful group. A stepwise increase in any one, in any order, of these five predictors being present, from one out of five and up to five out of five yielded an increasing positive predictive value for successful extubation of 88.3% (95% CI, 82.4 to 94.3), 88.4% (95% CI, 83.5 to 93.3), 96.3% (95% CI, 93.4 to 99.2), 97.4% (95% CI, 94.4 to 100), and 100% (95% CI, 90 to 100). Conjugate gaze, facial grimace, eye opening, purposeful movement, and tidal volume greater than 5 ml/kg were each individually associated with extubation success in pediatric surgical patients after volatile anesthetic. Further, the use of a multifactorial approach using these predictors, may lead to a more rational and robust approach to successful awake extubation.

Laryngeal afferent modulation of swallowing interneurons in the dorsal medulla in perfused rats.

The purpose of this study was to investigate the influence of laryngeal afferent inputs on brainstem circuits that mediate and transmit swallowing activity to the orofacial musculature. Experiments were performed on 19 arterially perfused juvenile rats. The activities of swallowing interneurons in relation to their respective motor outputs in the hypoglossal and vagus nerves were assessed during fictive swallowing with or without concurrent laryngeal sensory stimulation at intensities of 20, 40, and 60 μA. The hypoglossal nerve activity was gradually enhanced with increasing intensity of the sensory stimulation, while the vagus nerve activity was not altered. The activities of various interneurons were modulated by the laryngeal stimulation, but more than 50% of the recorded neurons were inhibited by the stimulation. Some interneurons demonstrated no obvious change in their discharge rates with laryngeal sensory stimulation during fictive swallowing. Laryngeal afferent inputs partially modulated the swallowing motor activity via enhanced or suppressed activities of the swallowing interneurons, while the essential motor pattern underlying the pharyngeal stage of swallowing remained basically unchanged. Thus, the output patterns of the complex sequential movements of swallowing could be basically predetermined and further adjusted according to sensory information related to the properties of the ingested food by a swallowing central pattern generator. NA Laryngoscope, 130: 1885-1893, 2020.

Unearthing a consistent bilateral R1 component of the laryngeal adductor reflex in awake humans.

The laryngeal adductor reflex (LAR) is an essential tracheobronchial protective mechanism resulting in vocal fold adduction to laryngeal stimulation. It was thought to consist of an early ipsilateral R1 component and a later, bilateral but highly centrally modulated R2 component. We recently demonstrated that bilateral R1 responses are robustly present in humans under general anesthesia. We herein give evidence that the R1 response is also bilateral in awake humans and is likely the primary component responsible for initiating the LAR. Seven volunteers were included (3 males, 4 females). The reflex was elicited by direct percutaneous monopolar needle stimulation of the internal superior laryngeal nerve. Electromyography traces from bilateral lateral cricoarytenoid muscles were recorded using hookwire electrodes. Reflex responses to variations in stimulus intensity and duration were evaluated. Bilateral R1 responses were recorded in all patients, even during deep inspiration when the vocal folds were maximally abducted. R1, but not R2, responses increased linearly in amplitude, with sequential increases in both stimulation intensity (1-8 mA) and duration (100-500 µsec) (Pearson correlation 0.94). Contradicting over 40 years of research, we demonstrate that the R1 LAR component is consistently bilateral in awake humans. It increases linearly with stimulus intensity and is unaffected by conscious state suggesting minimal central control. These findings may provide a means to objectively stratify patients for risk of laryngeal aspiration, even in unconscious states, and its potentially cardinal role in disease states such as laryngospasm and sudden infant death needs to be reevaluated. 4. Laryngoscope, 2581-2587, 2018.

A NOVEL ROLE OF THE DESCENDING ANALGESIA SYSTEM IN THE REGULATION OF VAGAL REFLEXES

The submedius nucleus of the thalamus (SubM), ventrolateral orbital cortex (VLO) and periaqueductal grey (PAG) constitute a well‐described pain modulatory pathway. Activation leads to depression of nociceptive inputs in the spinal cord via the rostromedial medulla and brainstem descending inhibitory systems. Using transynaptic anterograde viral tracing we noted a neural circuit derived from jugular ganglia vagal afferents innervating the respiratory tree projecting to the SubM, suggestive that vagal afferent pathways may be regulated by SubM‐VLO‐PAG descending modulatory system. In functional studies using urethane anesthetized Sprague Dawley rats, electrical stimulation of the larynx to activate vagal afferent fibres evoked respiratory slowing in a stimulus frequency dependent manner. Concomitant SubM activation via microinjections of 5 ug serotonin significantly inhibited reflex reductions in respiration when compared to vehicle controls (e.g., baseline respiratory rate of 117±4.7 breaths per minute (bpm), to 12±2.2 bpm and 69±5.9 bpm in vehicle and serotonin animals, respectively; p=0.0001, n=9/group). Chemogenetic activation of the SubM with the Gq‐DREADD demonstrated a similar inhibitory effect on respiratory slowing (86±7.6 bpm and 15±62.4 bpm in +m3D+1 mg/kg CNO and –m3D+1 mg/kg CNO animals, respectively; p=0.0001, n=3/group). This inhibitory effect was absent in animals receiving prior electrolytic lesion of the VLO. Moreover, lesion of the VLO facilitated respiratory slowing caused by laryngeal stimulation (6±6.6 bpm and 73.5±6.7 bpm in lesion and sham animals, respectively; p=0.0001, n=5/group), consistent with a tonic descending inhibitory influence over respiratory vagal afferent processing. Taken together, these data support the notion that the SubM‐VLO‐PAG descending modulatory system plays an import role in the regulation of bulbar visceral afferent processing.Support or Funding InformationA McGovern a a current recipient of a Peter Doherty Fellowship (National Health and Medical Research Council, Australia).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

International consensus (ICON) on comprehensive management of the laryngeal nerves risks during thyroid surgery

The laryngeal monitoring of the inferior and superior laryngeal nerves, and the vagus nerve, has advanced for last years, in practice of thyroid and parathyroid surgery. Different methods are used, using direct or indirect laryngeal stimulation and also intermittent or continuous nerve registration. At present time, various recommendations of it in the world use are reported, and availability of the tool used remains a limit in some countries. The aim of this Icon during Ifos 2017 was to share knowledge about laryngeal intraoperative nerve monitoring (LIONM) procedures and to evaluate current practices used to improve the quality of thyroid and parathyroid surgery. Benefits of LIONM were discussed with three experts (Pr G. Randolph from Boston, Pr Henning Dralle from Halle in Germany, Pr Hoon Yub KIM from Seoul). All of them have been actively involved in the development and use of laryngeal nerve monitoring during thyroid and parathyroid surgery.

Relationship Between Laryngeal Sensory Deficits, Aspiration, and Pneumonia in Patients with Dysphagia.

The laryngeal adductor reflex (LAR) is an airway protective reflex that manifests as a brief vocal fold closure in response to laryngeal stimulation. This study examined if the absence of the LAR in response to touch delivered by a laryngoscope is associated with penetration/aspiration or pneumonia in patients with dysphagia. Inpatients at a teaching hospital with clinical symptoms of dysphagia were recruited upon referral to the otolaryngology clinic for a swallowing evaluation. Otolaryngologists observed the status of secretions and touched each arytenoid with the tip of the laryngoscope. The patients were then asked to swallow 3-5mL grape gelatin and 3-5mL colored water. All procedures were video-recorded. Two independent raters noted absence/presence of the LAR and penetration/aspiration of pharyngeal secretions, gelatin, and water on the recorded videos. A diagnosis of pneumonia during the patient's entire hospital stay was determined by a review of the hospital's medical records. Statistical analyses were performed using Fisher's exact test. Sixty-one patients were included. Twenty-one patients (34.5%) did not exhibit the LAR. No association was found between the absent LAR and penetration or aspiration. There was, however, a significant association between an absence of the LAR and pneumonia development. Patients with an absent LAR had 6.8 times the odds of developing pneumonia as compared to those with a present LAR (OR 6.75; 95% CI 1.76-25.96; p<0.01). Using the LAR as a marker of laryngeal sensory function appears to be valuable for identifying patients at high risk of pneumonia.

Impact of high concentrations of sevoflurane on laryngeal reflex responses.

Exaggerated defensive upper airway reflexes, particularly laryngospasm, may cause hypoxemic damage, especially in children. General clinical experience suggests that laryngeal reflex responses are more common under light levels of anesthesia, and previous clinical studies have shown an inverse correlation between laryngeal responsiveness and depth of hypnosis. However, this seems to be less obvious in children anesthetized with sevoflurane. The aim of this study was to assess the impact of high concentrations of sevoflurane on laryngeal and respiratory reflex responses in spontaneously breathing children. Accordingly, we tested the hypothesis that laryngeal and respiratory reflex responses were completely suppressed in spontaneously breathing children when anesthetized with sevoflurane 4.7% (=MACED95Intubation ) as compared with sevoflurane 2.5% (=1MAC). In this prospective observational study, we tested the hypothesis that the incidence of laryngospasm evoked by laryngeal stimulation is diminished under high concentrations of sevoflurane. Following Ethics approval, trial registration, and informed consent, 40 children (3-7years) scheduled for elective surgery participated in the trial. All children received sevoflurane 2.5% (1 MAC) and 4.7% (ED95Intubation ) in random order with 5-min equilibration between the states. Under both conditions, distilled water was sprayed under bronchoscopic view onto the larynx. Potential laryngeal and respiratory reflex responses were assessed offline by a blinded reviewer. Laryngospasm (episodes lasting >10s) occurred in 12/38 (32%) of the patients anesthetized with sevoflurane 2.5%, vs 7/38 (18%) in those anesthetized with sevoflurane 4.7% (difference: OR 3.5; 95% CI [0.72-16.84], P=0.18). All other reflex responses (coughing, expiration reflexes, and spasmodic panting) were infrequent and were similar among the examined concentrations. Against our hypothesis, laryngospasm could still be observed in 18% of children under the higher concentration of sevoflurane (4.7%, ED95Intubation ).

Treatment algorithm of postoperative management of patients with chronic edematic polypous laryngitis

The authors conducted complex examination of 200 patients with chronic edematic polypous laryngitis and determined the specific aspects of clinical and functional condition of larynx of patients before and after the surgery and described the course of postoperative laryngitis. The article proves that the functional pathology of larynx revealed in 66% of post-surgery patients increases the duration of post-surgery dysphonia. It is proven that application of neuromuscular electrophonopedic stimulation of larynx facilitates normalization of larynx physiology by the 14th day after the operation, reducing sonorous voice recovery period in average by 7–14 days. Application of the proposed method made it possible to achieve significant increase in the efficiency of post­operative treatment of patients with chronic edematic polypous laryngitis.

The Role of the Paratrigeminal Nucleus in Vagal Afferent Evoked Respiratory Reflexes: A Neuroanatomical and Functional Study in Guinea Pigs.

The respiratory tree receives sensory innervation from the jugular and nodose vagal sensory ganglia. Neurons of these ganglia are derived from embryologically distinct origins and as such demonstrate differing molecular, neurochemical and physiological phenotypes. Furthermore, whereas nodose afferent neurons project to the nucleus of the solitary tract (nTS), recent neuroanatomical studies in rats suggest that jugular neurons have their central terminations in the paratrigeminal nucleus (Pa5). In the present study we confirm that guinea pigs demonstrate a comparable distinction between the brainstem terminations of nodose and jugular ganglia afferents. Thus, microinjection of fluorescently conjugated cholera toxin B (CT-B) neural tracers into the caudal nTS and Pa5 resulted in highly specific retrograde labeling of neurons in the nodose and jugular ganglia, respectively. Whereas, nodose neurons more often expressed 160 KD neurofilament proteins and the alpha3 subunit of Na+/K+ ATPase, significantly more jugular neurons expressed the neuropeptides substance P (SP) and, especially, Calcitonin Gene-Related Peptide (CGRP). Indeed, terminal fibers in the Pa5 compared to the nTS were characterized by their significantly greater expression of CGRP, further supporting the notion that jugular afferents project to trigeminal-related brainstem regions. Electrical stimulation of the guinea pig larynx following selective surgical denervation of the nodose afferent innervation to the larynx (leaving intact the jugular innervation) resulted in stimulus dependent respiratory slowing and eventual apnea. This jugular ganglia neuron mediated response was unaffected by bilateral microinjections of the GABAA agonist muscimol into the nTS, but was abolished by muscimol injected into the Pa5. Taken together these data confirm that jugular and nodose vagal ganglia afferent neurons innervate distinct central circuits and support the notion that multiple peripheral and central pathways mediate sensory responses associated with airway irritations.

Maternal omega‐3 supplementation reduces apnea duration induced by laryngeal chemoreflex stimulation in rat pups

Maternal omega‐3 supplementation reduces apnea duration induced by laryngeal chemoreflex stimulation in rat pups

Effect of gantacurium on evoked laryngospasm and duration of apnea in anesthetized healthy cats.

To evaluate whether the ultrashort-acting neuromuscular blocking agent gantacurium can be used to blunt evoked laryngospasm in anesthetized cats and to determine the duration of apnea without hemoglobin desaturation. 8 healthy adult domestic shorthair cats. Each cat was anesthetized with dexmedetomidine and propofol, instrumented with a laryngeal mask, and allowed to breathe spontaneously (fraction of inspired oxygen, 1.0). The larynx was stimulated by spraying sterile water (0.3 mL) at the rima glottidis; a fiberscope placed in the laryngeal mask airway was used to detect evoked laryngospasm. Laryngeal stimulation was performed at baseline; after IV administration of gantacurium at doses of 0.1, 0.3, and 0.5 mg/kg; and after the effects of the last dose of gantacurium had terminated. Duration of apnea and hemoglobin oxygen saturation (measured by means of pulse oximetry) after each laryngeal stimulation were recorded. Neuromuscular block was monitored throughout the experiment by means of acceleromyography on a pelvic limb. Laryngospasm was elicited in all cats at baseline, after administration of 0.1mg of gantacurium/kg, and after the effects of the last dose of gantacurium had terminated. The 0.3 and 0.5 mg/kg doses of gantacurium abolished laryngospasm in 3 and 8 cats, respectively, and induced complete neuromuscular block measured at the pelvic limb; the mean ± SE duration of apnea was 2 ± 1 minutes and 3 ± 1.5 minutes, respectively. Hemoglobin oxygen saturation did not decrease significantly after administration of any dose of gantacurium. Gantacurium may reduce tracheal intubation-associated morbidity in cats breathing oxygen.

Laryngeal reflex apnea in neonates: Effects of CO2 and the complex influence of hypoxia

We have examined influence of hypocapnia, mild hypercapnia and hypoxia on the durations of fictive apnea and respiratory disruption elicited by injection of 0.1ml of water into the laryngeal lumen—the laryngeal chemoreflex (LCR)—in 20 unanesthetized, decerebrate, vagotomized piglets aged 4–10 days that were paralyzed and ventilated with a constant frequency and tidal volume. The LCR was enhanced by hypocapnia and attenuated by hypercapnia as reported by others. The responses to laryngeal stimulation during hypoxia were varied and complex: some animals showed abbreviated responses during the tachypnea of early hypoxia, followed after 10–15min by more prolonged apnea and respiratory disruption accompanying the reduction in ventilatory activity that commonly occurs during sustained hypoxia in neonates. We speculate that this later hypoxic enhancement of the LCR may be due to accumulation of adenosine in the brain stem.