Laryngeal Activity Research Articles

Robot-assisted cervical esophagectomy with simultaneous transhiatal abdominal procedure for thoracic esophageal carcinoma.

Minimally invasive robot-assisted cervical esophagectomy has been sporadically reported as a novel thoracic esophagectomy technique for patients with thoracic esophageal carcinoma. Most reports indicate that the abdominal component of robot-assisted cervical esophagectomy is performed sequentially after the cervical phase. However, if the cervical and abdominal phases are performed simultaneously using a nerve integrity monitoring system with no administration of muscle relaxants, there are two major advantages: a reduced risk of recurrent nerve palsy and a shorter operative time. We herein report our experience performing novel robot-assisted transcervical esophagectomy with a simultaneous transhiatal abdominal approach using a nerve integrity monitoring system. Thirty cases of robot-assisted cervical esophagectomy performed from 2023 to April 2024 were reviewed. The operative and short-term surgical outcomes of this procedure were compared with those of robot-assisted cervical esophagectomy using a sequential abdominal approach, and the feasibility and efficacy of the simultaneous procedure were analyzed. All patients successfully underwent robot-assisted cervical esophagectomy with no intraoperative adverse events. There were no differences in the patients' demographic or operative data between the two groups. There was no difference in the mean operation time for the cervical procedure (p = 0.23). However, there was a significant difference in the total time for the whole procedure (sequential group: 453.8 ± 26.8min, simultaneous group: 291.2 ± 36.1min; p < 0.01). There were no differences in postoperative surgical complications between the groups. There was also no difference in the total number of surgically harvested mediastinal lymph nodes (p = 0.33). Robot-assisted transcervical esophagectomy, a new technique for thoracic esophageal cancer, was safe and feasible under intraoperative management using nerve integrity monitoring without muscle relaxants. This procedure facilitates intraoperative monitoring of recurrent laryngeal nerve activity, significantly shortening the total operative time.

Laryngeal Vibrotactile Stimulation Is Feasible, Acceptable To People With Unexplained Chronic Cough.

Unexplained chronic cough (UCC) is common and has significant impacts on quality of life. Ongoing cough can sensitize the larynx, increasing the urge to cough and perpetuating the cycle of chronic cough. Vibrotactile stimulation (VTS) of the larynx is a noninvasive stimulation technique that can modulate laryngeal somatosensory and motor activity. Study objectives were to assess feasibility and acceptability of VTS use by people with UCC. Secondarily, changes in cough-related quality of life measures were assessed. Adults with UCC recorded cough measures at baseline and after completing 2 weeks of daily VTS. Feasibility and acceptability were assessed through participant-reported device use and structured feedback. Cough-related quality of life measures were the Leicester Cough Questionnaire (LCQ) and the Newcastle Laryngeal Hypersensitivity Questionnaire (NLHQ). Nineteen adults participated, with mean age 67 years and cough duration 130 months. Notably, 93% of planned VTS sessions were logged, 94% of participants found the device comfortable to wear, 89% found it easy to operate and 79% would recommend it to others. Pre-post LCQ change achieved a minimal important difference (MID) (mean 1.3 [SD 2.4, p = 0.015]). NLHQ scores improved, but did not reach an MID. Laryngeal VTS use was feasible and acceptable for use by patients with UCC and was associated with a meaningful improvement in cough-related quality of life. Future studies will include VTS dose refinement and the inclusion of a comparison arm to further assess the potential for laryngeal VTS as a novel treatment modality for UCC. 4 Laryngoscope, 2024.

Towards enhanced functionality of vagus neuroprostheses through in silico optimized stimulation

Bioelectronic therapies modulating the vagus nerve are promising for cardiovascular, inflammatory, and mental disorders. Clinical applications are however limited by side-effects such as breathing obstruction and headache caused by non-specific stimulation. To design selective and functional stimulation, we engineered VaStim, a realistic and efficient in-silico model. We developed a protocol to personalize VaStim in-vivo using simple muscle responses, successfully reproducing experimental observations, by combining models with trials conducted on five pigs. Through optimized algorithms, VaStim simulated the complete fiber population in minutes, including often omitted unmyelinated fibers which constitute 80% of the nerve. The model suggested that all Aα-fibers across the nerve affect laryngeal muscle, while heart rate changes were caused by B-efferents in specific fascicles. It predicted that tripolar paradigms could reduce laryngeal activity by 70% compared to typically used protocols. VaStim may serve as a model for developing neuromodulation therapies by maximizing efficacy and specificity, reducing animal experimentation.

Uncovering the neural control of laryngeal activity and subglottic pressure in anaesthetized rats: insights from mesencephalic regions

To assess the possible interactions between the dorsolateral periaqueductal gray matter (dlPAG) and the different domains of the nucleus ambiguus (nA), we have examined the pattern of double-staining c-Fos/FoxP2 protein immunoreactivity (c-Fos-ir/FoxP2-ir) and tyrosine hydroxylase (TH) throughout the rostrocaudal extent of nA in spontaneously breathing anaesthetised male Sprague–Dawley rats during dlPAG electrical stimulation. Activation of the dlPAG elicited a selective increase in c-Fos-ir with an ipsilateral predominance in the somatas of the loose (p < 0.05) and compact formation (p < 0.01) within the nA and confirmed the expression of FoxP2 bilaterally in all the domains within the nA. A second group of experiments was made to examine the importance of the dlPAG in modulating the laryngeal response evoked after electrical or chemical (glutamate) dlPAG stimulations. Both electrical and chemical stimulations evoked a significant decrease in laryngeal resistance (subglottal pressure) (p < 0.001) accompanied with an increase in respiratory rate together with a pressor and tachycardic response. The results of our study contribute to new data on the role of the mesencephalic neuronal circuits in the control mechanisms of subglottic pressure and laryngeal activity.

Role of the caudal Nucleus Tractus Solitarius and the Postinspiratory Complex in swallow production

The production of swallowing and its coordination with breathing is essential for homeostasis in most organisms. The postinspiratory complex (PiCo) is thought to regulate the transition between swallowing and breathing. Activation of PiCo triggers swallow production and stimulates laryngeal activation in a respiratory phase specific manner. However, little is known about PiCo’s role in swallow generation, which is thought to be controlled by the caudal portion of the Nucleus Tractus Solitarius (cNTS), presumably the swallow pattern generator (SPG). We hypothesize the cNTS is necessary for PiCo to trigger a swallow. Using both male and female Vglut2cre mice, a cre-dependent ChR2 AAV was bilaterally injected into PiCo and a cre-dependent inhibitory DREADD was bilaterally injected into the cNTS, specifically targeting the interstitial (SolI) and intermediate (SolIM) solitary nucleus. Twenty-one days after injection, using our freely breathing urethane anesthetized mouse model, swallows were stimulated by 1) injection of water into the oral cavity and 2) optogenetic stimulation of PiCo neurons; before and after DREADD activator, clozapine-N-oxide (CNO). Swallow and laryngeal activity were measured via monopolar suction electrodes of the hypoglossal (XII) and vagus (X) nerves as well as bipolar electromyogram (EMG) of the submental, laryngeal complex and costal diaphragm muscles. Post-hoc histological analysis was done to confirm areas of interest were targeted. We found that after activation of the inhibitory DREADD, located in the cNTS, swallow was not evoked by water stimulation nor optogenetic stimulation. We propose that PiCo relies on direct feedback from the cNTS in order to trigger swallow production. NIH F32 HL160102. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic intermittent hypoxia reveals role of the Postinspiratory Complex in the mediation of normal swallow production.

Obstructive sleep apnea (OSA) is a prevalent sleep-related breathing disorder that results in multiple bouts of intermittent hypoxia. OSA has many neurological and systemic comorbidities, including dysphagia, or disordered swallow, and discoordination with breathing. However, the mechanism in which chronic intermittent hypoxia (CIH) causes dysphagia is unknown. Recently, we showed the postinspiratory complex (PiCo) acts as an interface between the swallow pattern generator (SPG) and the inspiratory rhythm generator, the preBötzinger complex, to regulate proper swallow-breathing coordination (Huff et al., 2023). PiCo is characterized by interneurons co-expressing transporters for glutamate (Vglut2) and acetylcholine (ChAT). Here we show that optogenetic stimulation of ChATcre:Ai32, Vglut2cre:Ai32, and ChATcre:Vglut2FlpO:ChR2 mice exposed to CIH does not alter swallow-breathing coordination, but unexpectedly disrupts swallow behavior via triggering variable swallow motor patterns. This suggests that glutamatergic-cholinergic neurons in PiCo are not only critical for the regulation of swallow-breathing coordination, but also play an important role in the modulation of swallow motor patterning. Our study also suggests that swallow disruption, as seen in OSA, involves central nervous mechanisms interfering with swallow motor patterning and laryngeal activation. These findings are crucial for understanding the mechanisms underlying dysphagia, both in OSA and other breathing and neurological disorders.

Chronic intermittent hypoxia reveals role of the Postinspiratory Complex in the mediation of normal swallow production

Obstructive sleep apnea (OSA) is a prevalent sleep-related breathing disorder that results in multiple bouts of intermittent hypoxia. OSA has many neurological and systemic comorbidities, including dysphagia, or disordered swallow, and discoordination with breathing. However, the mechanism in which chronic intermittent hypoxia (CIH) causes dysphagia is unknown. Recently, we showed the postinspiratory complex (PiCo) acts as an interface between the swallow pattern generator (SPG) and the inspiratory rhythm generator, the preBötzinger complex, to regulate proper swallow-breathing coordination (Huff et al., 2023). PiCo is characterized by interneurons co-expressing transporters for glutamate (Vglut2) and acetylcholine (ChAT). Here we show that optogenetic stimulation of ChATcre:Ai32, Vglut2cre:Ai32, and ChATcre:Vglut2FlpO:ChR2 mice exposed to CIH does not alter swallow-breathing coordination, but unexpectedly disrupts swallow behavior via triggering variable swallow motor patterns. This suggests that glutamatergic–cholinergic neurons in PiCo are not only critical for the regulation of swallow-breathing coordination, but also play an important role in the modulation of swallow motor patterning. Our study also suggests that swallow disruption, as seen in OSA, involves central nervous mechanisms interfering with swallow motor patterning and laryngeal activation. These findings are crucial for understanding the mechanisms underlying dysphagia, both in OSA and other breathing and neurological disorders.

Central Autonomic Mechanisms Involved in the Control of Laryngeal Activity and Vocalization.

In humans, speech is a complex process that requires the coordinated involvement of various components of the phonatory system, which are monitored by the central nervous system. The larynx in particular plays a crucial role, as it enables the vocal folds to meet and converts the exhaled air from our lungs into audible sounds. Voice production requires precise and sustained exhalation, which generates an air pressure/flow that creates the pressure in the glottis required for voice production. Voluntary vocal production begins in the laryngeal motor cortex (LMC), a structure found in all mammals, although the specific location in the cortex varies in humans. The LMC interfaces with various structures of the central autonomic network associated with cardiorespiratory regulation to allow the perfect coordination between breathing and vocalization. The main subcortical structure involved in this relationship is the mesencephalic periaqueductal grey matter (PAG). The PAG is the perfect link to the autonomic pontomedullary structures such as the parabrachial complex (PBc), the Kölliker-Fuse nucleus (KF), the nucleus tractus solitarius (NTS), and the nucleus retroambiguus (nRA), which modulate cardiovascular autonomic function activity in the vasomotor centers and respiratory activity at the level of the generators of the laryngeal-respiratory motor patterns that are essential for vocalization. These cores of autonomic structures are not only involved in the generation and modulation of cardiorespiratory responses to various stressors but also help to shape the cardiorespiratory motor patterns that are important for vocal production. Clinical studies show increased activity in the central circuits responsible for vocalization in certain speech disorders, such as spasmodic dysphonia because of laryngeal dystonia.

Atypical Activation of Laryngeal Somatosensory-Motor Cortex During Vocalization in People With Unexplained Chronic Cough

Unexplained chronic cough is common and has substantial negative quality-of-life implications, yet its causes are not well understood. A better understanding of how peripheral and central neural processes contribute to chronic cough is essential for treatment design. To determine if people with chronic cough exhibit signs of abnormal neural processing over laryngeal sensorimotor cortex during voluntary laryngeal motor activity such as vocalization. This was a cross-sectional study of a convenience sample of participants with chronic cough and healthy participants. Testing was performed in an acoustically and electromagnetically shielded chamber. In a single visit, electroencephalographic (EEG) signals were recorded from participants with chronic cough and healthy participants during voice production. The chronic cough group participants presented with unexplained cough of 8 weeks or longer duration with prior medical evaluation including negative results of chest imaging. None of the participants had a history of any neurologic disease known to impair vocalization or swallowing. Data collection for the healthy control group occurred from February 2 to June 28, 2018, and for the chronic cough group, from November 22, 2021, to June 21, 2022. Data analysis was performed from May 1 to October 30, 2022. Participants with or without chronic cough. Event-related spectral perturbation over the laryngeal area of somatosensory-motor cortex from 0 to 30 Hz (ie, θ, α, and β bands) and event-related coherence as a measure of synchronous activity between somatosensory and motor cortical regions. The chronic cough group comprised 13 participants with chronic cough (mean [SD] age, 63.5 [7.8] years; 9 women and 4 men) and the control group, 10 healthy age-matched individuals (mean [SD] age, 60.3 [13.9] years; 6 women and 4 men). In the chronic cough group, the typical movement-related desynchronization over somatosensory-motor cortex during vocalization was significantly reduced across θ, α, and β frequency bands when compared with the control group. This cross-sectional study found that the typical movement-related suppression of brain oscillatory activity during vocalization is weak or absent in people with chronic cough. Thus, chronic cough affects sensorimotor cortical activity during the asymptomatic voluntary activation of laryngeal muscles.

Role of the postinspiratory complex in regulating swallow-breathing coordination and other laryngeal behaviors.

Breathing needs to be tightly coordinated with upper airway behaviors, such as swallowing. Discoordination leads to aspiration pneumonia, the leading cause of death in neurodegenerative disease. Here, we study the role of the postinspiratory complex (PiCo) in coordinating breathing and swallowing. Using optogenetic approaches in freely breathing anesthetized ChATcre:Ai32, Vglut2cre:Ai32 and intersectional recombination of ChATcre:Vglut2FlpO:ChR2 mice reveals PiCo mediates airway protective behaviors. Activation of PiCo during inspiration or the beginning of postinspiration triggers swallow behavior in an all-or-nothing manner, while there is a higher probability for stimulating only laryngeal activation when activated further into expiration. Laryngeal activation is dependent on stimulation duration. Sufficient bilateral PiCo activation is necessary for preserving the physiological swallow motor sequence since activation of only a few PiCo neurons or unilateral activation leads to blurred upper airway behavioral responses. We believe PiCo acts as an interface between the swallow pattern generator and the preBötzinger complex to coordinate swallow and breathing. Investigating PiCo's role in swallow and laryngeal coordination will aid in understanding discoordination with breathing in neurological diseases.

Different facial cues for different speech styles in Mandarin tone articulation

Visual facial information, particularly hyperarticulated lip movements in clear speech, has been shown to benefit segmental speech perception. Little research has focused on prosody, such as lexical tone, presumably because production of prosody primarily involves laryngeal activities not necessarily distinguishable through visible articulatory movements. However, there is evidence that head, eyebrow, and lip movements correlate with production of pitch-related variations. One subsequent question is whether such visual cues are linguistically meaningful. In this study, we compare movements of the head, eyebrows and lips associated with plain (conversational) vs. clear speech styles of Mandarin tone articulation to examine the extent to which clear-speech modifications involve signal-based overall exaggerated facial movements or code-based enhancement of linguistically relevant articulatory movements. Applying computer-vision techniques to recorded speech, visible movements of the frontal face were tracked and measured for 20 native Mandarin speakers speaking in two speech styles: plain and clear. Thirty-three head, eyebrow and lip movement features based on distance, time, and kinematics were extracted from each individual tone word. A random forest classifier was used to identify the important features that differentiate the two styles across tones and for each tone. Mixed-effects models were then performed to determine the features that were significantly different between the two styles. Overall, for all the four Mandarin tones, we found longer duration and greater movements of the head, eyebrows, and lips in clear speech than in plain speech. Additionally, across tones, the maximum movement happened relatively earlier in clear than plain speech. Although limited evidence of tone-specific modifications was also observed, the cues involved overlap with signal-based changes. These findings suggest that visual facial tonal modifications for clear speech primarily adopt signal-based general emphatic cues that strengthen signal saliency.

A combined cuff electrode array for organ-specific selective stimulation of vagus nerve enabled by Electrical Impedance Tomography.

Previously developed spatially-selective Vagus Nerve Stimulation (sVNS) allows the targeting of specific nerve fascicles through current steering in a multi-electrode nerve cuff but relies on a trial-and-error strategy to identify the relative orientation between electrodes and fascicles. Fast Neural Electrical Impedance Tomography (FN-EIT) has been recently used for imaging neural traffic in the vagus nerves of pigs in a cross-correlation study with sVNS and MicroCT fascicle tracking. FN-EIT has the potential for allowing targeted sVNS; however, up to now, stimulation and imaging have been performed with separate electrode arrays. In this study, different options were evaluated in-silico to integrate EIT and stimulation into a single electrode array without affecting spatial selectivity. The original pig vagus EIT electrode array geometry was compared with a geometry integrating sVNS and EIT electrodes, and with direct use of sVNS electrodes for EIT imaging. Modelling results indicated that both new designs could achieve image quality similar to the original electrode geometry in all tested markers (e.g., co-localisation error <100 µm). The sVNS array was considered to be the simplest due to the lower number of electrodes. Experimental results from testing evoked EIT imaging of recurrent laryngeal activity using electrodes from the sVNS cuff returned a signal-to-noise ratio similar to our previous study (3.9 ± 2.4 vs. 4.1 ± 1.5, N = 4 nerves from 3 pigs) and a lower co-localisation error (≈14% nerve diameter vs. ≈25%, N = 2 nerves from 2 pigs). Performing FN-EIT and sVNS on the same nerve cuff will facilitate translation to humans, simplify surgery and enable targeted neuromodulation strategies.

Funkční hodnocení laryngoskopického vyšetření a souvislost s kvalitou hlasu a parametry hlasového pole

Summary Introduction: Previous laryngoscopy evaluation protocols have mostly focused on assessment of glottal status and morphological description of vocal folds’ shape and oscillations. The basic functional manifestations of laryngeal use, according to new protocols, include a description of supraglottic laryngeal activity. Methods: Laryngoscopic evaluation was performed as a perceptual test, performed online, using a web-based application. The degree and type of glottal insufficiency and the degree of anterior, posterior compression and lateral-medial (L-M) compression separately for each side were evaluated by a total of 15 respondents in a total of 26 video recordings of laryngoscopic examinations. In addition, the correlations between listening evaluations of the voice using modified GRBAS scales and voice range profile parameters were investigated. Results: The ratings of the laryngoscopic scales had well to excellent agreement. Agreement for type of insufficiency was just moderate. The associated ratings of L-M compression on the right and left sides showed correlations. For listening evaluation, medial compression was found to be related to the perception of habitual voice strain, and to strain and instability in the pitch range of the change of registers of the singing voice. Degree of insufficiency predicted less fullness of habitual voice in general but was also related to vocal dyspnea and weakness when calling. At the same time, it was largely responsible for the deterioration of the quality of the singing voice. Medial compression systematically reduced pitch range and the area of the voice range profile. Conclusion: The results of the perceptual evaluation can be used in further education. On their basis, didactic material for training the assessment of supraglottic laryngeal activity was prepared and published in the form of an online tutorial. The degree of insufficiency generally affects various characteristics of the speaking and singing voice. Medial compression systematically affects only the strain of the speaking voice, while in the singing voice it accentuates the strain and instability of the transitional region between registers and impairs the production of high pitches. Key words laryngoscopy – visual evaluation – voice range profile – GRBAS

Laryngeal and swallow dysregulation following acute cervical spinal cord injury.

Laryngeal function is vital to airway protection. Although swallow is mediated by the brainstem, the mechanism underlying the increased risk of dysphagia after cervical spinal cord injury (SCI) is unknown. We hypothesized that: 1) loss of descending phrenic drive affects swallow and breathing differently, and 2) loss of ascending spinal afferent information alters swallow regulation. We recorded electromyograms (EMGs) from upper airway and chest wall muscles in freely breathing pentobarbital-anesthetized cats and rats. Laryngeal abductor activity during inspiration increased about twofold following C2 lateral hemisection. Ipsilateral to the injury, the crural diaphragm EMG amplitude was reduced during breathing (62 ± 25% change postinjury), but no animal had complete termination of activity; 75% of animals had increased contralateral diaphragm recruitment, but this did not reach significance. During swallow, laryngeal adductor and pharyngeal constrictor muscles increased activity, and diaphragm activity was bilaterally suppressed. This was unexpected because of the ipsilateral-specific response during breathing. Swallow-breathing coordination was disrupted by injury, and more swallows occurred during early expiration. Finally, to determine if the chest wall is a major source of feedback for laryngeal regulation, we performed T1 total transections in rats. As in the C2 lateral hemisection, inspiratory laryngeal recruitment was the first feature noted after injury. In contrast to the C2 lateral hemisection, diaphragmatic drive increased after T1 transection. Overall, we found that SCI alters laryngeal drive during swallow and breathing, and alters swallow-related diaphragm activity. Our results show behavior-specific effects, suggesting that swallow is affected more than breathing is by SCI, and emphasizing the need for additional studies on the effect of ascending afferents from the spinal cord on laryngeal function.NEW & NOTEWORTHY This is the first manuscript to determine the impact of cSCI on laryngeal and swallow function, and to describe a possible mechanism for dysphagia and altered airway protection after injury.

Effect of Language on Voice Quality: An Acoustic Study of Bilingual Speakers of Mandarin Chinese and English

Introduction: Previous studies reported discrepant vocal qualities associated with different languages. However, possible physical differences associated with speakers of different ethnicities were not accounted for. The present study attempted to examine the effect of language on one’s voice quality by eliminating the potential effects of physical differences associated with speakers of different languages. Methods: Sixteen Chinese and fourteen Americans who were proficient in both Mandarin Chinese and English were recruited. They were instructed to read one Chinese and one English passage. Time-domain and long-term average spectral analyses were carried out, and speaking fundamental frequency (sF0), jitter, shimmer, and first spectral peak (FSP), mean spectral energy (MSE), and spectral tilt (ST) were measured using Praat. Results: Acoustic measures revealed no differences in sF0, FSP, and ST between Americans and Chinese. However, jitter, shimmer, and MSE values appeared to be affected by ethnicity (Chinese vs. Americans). Jitter and shimmer tended to be greater when someone was speaking his/her mother tongue. For language effect, Chinese was found to be associated with a faster rate of vocal fold vibration than English. MSE was higher for Chinese than English produced by Chinese, but not by American speakers, despite the similar ST in both languages. Discussion/Conclusion: Based on speech samples obtained from the balanced groups of bilingual speakers, the findings confirmed the presence of language effect on one’s voice quality. Laryngeal activity appeared to be affected by the language being spoken.

Neonatal opioid withdrawal syndrome disrupts the ventral swallow pattern generator in germline‐GCaMP6F mouse

Opioid exposure during gestation can lead to neonatal opioid withdrawal syndrome (NOWS) at birth. A feature of NOWS is dysphagia. To better understand the contribution of dysregulated central control to dysphagia in NOWs infants, we compared fictive swallow in neonate (P2‐P6) control mice and mice exposed to methadone from E14.5 onwards. Propriobulbar interneuronal and cranial premotoneuronal networks that coordinate orofacial and laryngeal activity during feeding, as well as constituents of the ventral respiratory column were recorded optically in mice expressing the genetically encoded Ca2+ indicator GCaMP6F in the germline. In the sagittally‐sectioned isolated brainstem, swallow can be evoked by electrical stimulation of command neurons along the dorsomedial edge of the preparation. In vitro swallow is defined as a burst at the hypoglossal nerve (XIIn) unaccompanied by phrenic (C4) motor output. In control animals evoked swallow was accompanied by sequential activation of networks dorsal and medial to the facial nucleus (VIIn), a nucleus in the intermediate reticular formation implicated in vibrissal control (vIRT), and (pre‐)motoneurons along the nucleus ambiguus (NA). In opioid‐exposed pups fictive swallow could reliably be evoked, but only networks dorsomedial to VIIn were reliably activated, while vIRT and NA networks were silent. The distribution of ChAT+, phox2b+, and SST+ neurons was the same in control and MTD‐exposed mice, as were the networks active during inspiration. These findings suggest that dysphagia may at least in part be due to network‐level dysregulation of central networks mediating swallow, but not to gross developmental abnormality of these networks. Because neonate feeding behaviors are highly conserved in mammals, these findings suggest that the sagittally‐sectioned mouse hindbrain provides a platform to investigate the contribution of central networks to dysphagia in NOWS infants.

Patterns of cardio-respiratory motor outputs during acute and subacute exposure to chlorpyrifos in an ex-vivo in situ preparation in rats

While a considerable body of literature has characterized the clinical features induced by organophosphate pesticides, the field lacks scrutiny into cardio-respiratory changes in different phases of poisoning. Herein, we evaluated the impact of chlorpyrifos (CPF) and its active metabolite chlorpyrifos-oxon (CPO) on the cardiorespiratory system during acute and subacute phases of poisoning using an in situ experimental rodent model. CPF (30 mg/kg) was injected intraperitoneally to rats beforehand (24 h) whereas CPO (15 mg/kg) was added into the perfusate reservoir to evaluate the effects on the motor outputs throughout the three phases of the respiratory cycle: inspiration, post-inspiration and late expiration. Phrenic, recurrent laryngeal (RLN) and thoracic sympathetic nerve activity (tSNA) were recorded. Heart rate was derived from the electrocardiogram (ECG) and the baro- and chemo-reflexes tested. CPF and CPO led to a time-dependent change in cardiorespiratory motor outputs. In the acute phase, the CPO induced bradypnea, transiently reduced the inspiratory time (TI), and increased the amplitude of phrenic. Post-inspiratory (PI) discharge recorded from the RLN was progressively reduced while tSNA was increased. CPO significantly depressed the chemoreflex but had no effect on baroreflex. During subacute phase, CPF prolongated TI with no effect on respiratory rate. Both the RLN PI discharge, the chemoreflex and the baroreflex sympathetic gain were reduced. In addition, both CPF and CPO shifted the cardiac sympatho-vagal balance towards sympathetic dominance. Our data show that different phases of poisoning are associated with specific changes in the cardio-respiratory system and might therefore demand distinct approaches by health care providers.

Effect of remimazolam on intraoperative neuromonitoring during thyroid surgery: a case series.

Intraoperative neuromonitoring is widely used to prevent accidental injury during thyroid surgery. Anesthesia should be performed without muscle relaxant or agents with high muscle-relaxant potency. Remimazolam, a novel intravenous anesthetic, became available for clinical use in 2020. Remimazolam is an ultra-short-acting benzodiazepine with a very high clearance rate. However, there are very few data regarding its effect on currently used intraoperative neurological monitoring. Five patients underwent thyroid surgery using intraoperative recurrent laryngeal neuromonitoring. In all cases, intubation was performed after the administration of rocuronium. Anesthesia was maintained by continuous administration of remimazolam at the recommended dose and remifentanil, and no additional rocuronium or sugammadex was administered. Recurrent laryngeal nerve activity could be detected at the first stimulus after surgery was started, and monitoring continued thereafter. Intraoperative monitoring was performed without problems and all surgeries were completed without any complications. Anesthesia with remimazolam at the normal dose did not prolong the time to first positive electromyogram in patients undergoing thyroid surgery, and enables intraoperative recurrent laryngeal nerve monitoring to be performed without any serious perioperative adverse events. Remimazolam may provide a comparable quality of anesthesia to that of existing drugs for neuromonitoring during thyroid surgery.

A theoretical model to elucidate the elusive concept ‘voice' for interpreters

ABSTRACT This paper is an attempt to elucidate the concept of voice for interpreters in relation to the equally elusive concept pleasant voice for interpreters. The point of departure is that the concept voice for interpreting has to do with the physical properties of a speaker’s voice, which may lead to the effect that a speaker’s voice is heard as pleasant or unpleasant by a listener, depending on how a speaker uses or deploys these physical properties. The paper employs an interdisciplinary approach to reviewing relevant literature and shows that for better interpreter education and interpreting assessment, there is a need to unravel, and unify existing understandings of the concept voice. A new definition is therefore proposed. The new definition consists of a cluster of suprasegmental features resulted from supralaryngeal and laryngeal activities and incorporates in what are traditionally known as fluency features in interpreting. The paper goes on to discuss the potential benefits and implications of the newly proposed definition for both interpreter training and interpreting studies.

Optogenetic stimulation of postinspiratory complex (PiCo) reveals hub for postinspiratory laryngeal closure and swallow related behaviors

Little is known about the central control of postinspiration, a phase critical for vocalization, cough, swallow and laryngeal control (closure). Laryngeal activity serves dual purposes for airway protection during swallow and for mechanical slowing of expiration. Dysregulation of laryngeal activity during postinspiratory behaviors can allow foreign material/food/liquid to enter the larynx and trachea (aspiration) and cause pneumonia, a leading cause of death among many central nervous system disorders. Schluckatmung (swallow breath) is the activation of the diaphragm during swallowing which creates a negative trans-diaphragmatic pressure aiding in the transition of the bolus from the pharynx to the esophagus. The Postinspiratory complex (PiCo), a medullary region composed of neurons that uniquely co-express both cholinergic and glutamatergic markers, has been shown to be active during postinspiration, reset the respiratory rhythm when stimulated, and is proposed as the pattern generator for postinspiration. However, the role of PiCo in other postinspiratory behaviors such as swallow and the neural coordination of inspiration, postinspiration and swallow is poorly understood. Our preliminary data revealed that activation of PiCo can trigger not only postinspiration, but also swallow, and both behaviors reset the respiratory rhythm. To evaluate the role PiCo plays in postinspiratory behaviors we targeted both cholinergic and glutamatergic neurons by optogenetically stimulating PiCo in anesthetized spontaneously breathing in-vivo adult ChATcre/Ai32(ChR2) and Vglut2cre/Ai32 mice. The ventral surface of the brainstem was exposed to place bilateral glass fiber optics connected to a blue (447nm) laser over the ventral surface in the region of PiCo using pulse durations ranging from 40-200ms. Swallow and postinspiratory laryngeal activity were measured via monopolar suction electrodes of the hypoglossal (XII) and vagus (X) nerves as well as bipolar electromyogram (EMG) of the submental and laryngeal complex and costal diaphragm muscles. We found that optogenetic stimulation of ChAT neurons applied at random across different phases of breathing resulted in a significantly higher probability of triggering a swallow during inspiration than triggering laryngeal closure (p=0.02). Reset of the respiratory rhythm is contingent upon stimulation of either swallow or laryngeal closure, whereas no behavioral response to the laser pulse results in an unchanged respiratory rhythm. We found that stimulating Vglut2 neurons in PiCo evoked both swallow and laryngeal postinspiratory activity. Of the 97 swallows triggered by optogenetic stimulation of Vglut2 neurons, schluckatmung was present in 67 swallows, whereas schluckatmung is never triggered during ChAT stimulation at PiCo. Our data indicates that PiCo is a hub for the generation of both postinspiratory activity and swallowing. The activation of swallowing may involve neurons in the nTS implicated in the generation of swallowing.