Association Between Laryngeal Sensation, Pre-swallow Secretions and Pharyngeal Residue on Fiberoptic Endoscopic Examination of Swallowing

Training to Analyze Functional Parameters with Fiberoptic Endoscopic Evaluation of Swallowing: A Scoping Review

Analyzing fiberoptic endoscopic evaluation of swallowing (FEES) is challenging and requires training to ensure the proficiency of health professionals and improve reliability. This scoping review aims to identify and map the available evidence on training health professionals to analyze FEES functional parameters. The method proposed by the Joanna Briggs Institute and the PRISMA-ScR guidelines were followed. The search was performed in MEDLINE, Cochrane Library, Embase, Web of Science, Scopus, CINAHL databases, and in the gray literature. Two blinded independent reviewers screened articles by title and abstract. Then, they read the full text of the included reports, considering the eligibility criteria. Data were extracted using a standardized form. Six studies met the established eligibility criteria, published between 2009 and 2022, with few participants. All these studies addressed training as part of the process to validate a rating scale. No standardized criteria were observed regarding the selection of experts and participants, training structure, and outcome measures to assess participants' competence. The reviewed literature indicates that training must be developed to equip students and health professionals who treat dysphagia, enabling them to analyze the functional parameters of the FEES, considering variables that may influence the participants' performance.

Role of TRPV1 in electroacupuncture-mediated signal to the primary sensory cortex during regulation of the swallowing function

AIMS

Electroacupuncture (EA) at the Lianquan (CV23) could alleviate swallowing dysfunction. However, current knowledge of its neural modulation focused on the brain, with little evidence from the periphery. Transient receptor potential channel vanilloid subfamily 1 (TRPV1) is an ion channel predominantly expressed in sensory neurons, and acupuncture can trigger calcium ion (Ca2+ ) wave propagation through active TRPV1 to deliver signals. The present study aimed to investigate whether TRPV1 mediated the signal of EA to the primary sensory cortex (S1) during regulation of swallowing function.

METHODS

Blood perfusion was evaluated by laser speckle contrast imaging (LSCI), and neuronal activity was evaluated by fiber calcium recording and c-Fos staining. The expression of TRPV1 was detected by RNA-seq analysis, immunofluorescence, and ELISA. In addition, the swallowing function was assessed by in vivo EMG recording and water consumption test.

RESULTS

EA treatment potentiated blood perfusion and neuronal activity in the S1, and this potentiation was absent after injecting lidocaine near CV23. TRPV1 near CV23 was upregulated by EA-CV23. The blood perfusion at CV23 was decreased in the TRPV1 hypofunction mice, while the blood perfusion and the neuronal activity of the S1 showed no obvious change. These findings were also present in post-stroke dysphagia (PSD) mice.

CONCLUSION

The TRPV1 at CV23 after EA treatment might play a key role in mediating local blood perfusion but was not involved in transferring EA signals to the central nervous system (CNS). These findings collectively suggested that TRPV1 may be one of the important regulators involved in the mechanism of EA treatment for improving swallowing function in PSD.

The effectiveness of ultrasound-guided injection of BTX-A in the management of sialorrhea in neurogenic dysphagia patients

Objective

To evaluate the effectiveness of ultrasound-guided injection of botulinum toxin type A (BTX-A) in treating sialorrhea.

Methods

We recruited 32 sialorrhea subjects and they received an ultrasound-guided injection of BTX-A. The extent of salivation was evaluated according to the Visual Analog Scale (VAS), Drooling Severity and Frequency Scale (DSFS), and Saliva Flow Rate (SFR). Laryngeal secretions were evaluated based on Fiberoptic Endoscopic Evaluation of Swallowing (FEES) rated according to the Murray Secretion Scale (MSS). We assessed the extent of salivation and laryngeal secretions before injection and at 1, 2, and 4 weeks after injection.

Results

The scores for the VAS, DSFS-S, DSFS-F, and DSFS-T decreased significantly at 1, 2, and 4 weeks after injection compared with before injection (p < .05). Based on VAS, the efficacy was substantially higher at 2 and 4 weeks after injection than at 1 week after injection (p < .05). According to DSFS-S and DSFS-T, the efficacy was significantly higher at 4 weeks than at 1 week after injection (p < .05). The SFR and MSS scores at 1 and 2 weeks after injection were superior to those before injection (p < .05). Meanwhile, the SFR score 2 weeks after injection was superior to that 1 week after injection (p < .05).

Conclusion

The ultrasound-guided injection of BTX-A can effectively reduce saliva secretion in patients with neurogenic dysphagia. Furthermore, it has the advantages of early onset time and lasting curative effects, which indicates that clinical promotion and application of this technique are justified.

Level of Evidence

Level 3.

Accumulated Secretions and Associated Aerodigestive Function in Patients With Dysphagia

PURPOSE

Accumulated pharyngo-laryngeal secretions are associated with dysphagia, aspiration, and poor health outcomes. Despite ongoing developments in the evaluation of pharyngo-laryngeal secretions, understanding of the underlying mechanisms is limited. Pathophysiology associated with accumulated secretions is needed to guide tailored, targeted treatment pathways. This study reports the prevalence of accumulated pharyngo-laryngeal secretions in a large acute care caseload and explores the relationship between secretions and aerodigestive function.

METHOD

Consecutive inpatients (N = 222) referred for flexible endoscopic evaluation of swallow (FEES) with suspected dysphagia following assessment by a speech-language pathologist were recruited (43% neurological, 22% neurosurgical, 20% critical care, 15% other), and 250 standardized FEES were completed (222 first FEES, 28 repeat FEES). The assessment protocol included secretion assessment using the New Zealand Secretion Scale (NZSS), pharyngeal squeeze maneuver, laryngeal motor and sensory assessment, Penetration-Aspiration Scale, and Yale Pharyngeal Residue Severity Rating Scale. Urge-to-clear ratings were collected during endoscopy. Cough peak expiratory flow and swallow frequency measures were also collected, as well as clinical outcomes at time of discharge.

RESULTS

There was a high incidence of accumulated secretions, with 77% of inpatients having elevated NZSS (Mdn = 3, range: 0-7) and 37% with pooled laryngeal secretions. Accumulated secretions were associated with reduced swallow frequency, reduced laryngeal adductor reflex, impaired pharyngeal squeeze maneuver, and peak expiratory flow. NZSS scores also correlated with swallow measures (Penetration-Aspiration Scale and Yale Pharyngeal Residue Severity Rating Scale) and patient outcomes including diet recommendations at discharge and pneumonia during admission.

CONCLUSIONS

This large study contributes to evidence associating both sensory and motor impairments with secretion accumulation and aspiration risk. Further exploration of the key physiological mechanisms contributing to accumulated secretions will serve as markers to provide proof of principle for targets for secretion management protocols.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24101667.

Assessment of Laryngeal Sensory Function using a Tactile Aesthesiometer in Healthy Adults

INTRODUCTION

Laryngeal sensory function in healthy adults was assessed through the delivery of tactile stimuli using Cheung-Bearelly monofilaments.

METHODS

37 healthy adults were recruited with 340 tactile stimuli analyzed. Four calibrated tactile stimuli were delivered to three laryngeal sites: false vocal fold (FVF), aryepiglottic fold (AEF), and lateral pyriform sinus (LPS). Primary outcome was the elicitation of laryngeal adductor reflex (LAR). Secondary outcomes were gag, patient-reported laryngeal sensation (PRLS), and perceptual strength. Analysis was performed with mixed effects logistic regression modeling.

RESULTS

Positive LAR was observed in 35.7%, 70.2%, and 91.2% of stimuli at LPS, AEF, and FVF respectively. LAR rates were significantly associated with laryngopharyngeal subsite (p < 0.001), tactile force (p = 0.001), age (p = 0.022) and sex (p = 0.022). LAR, gag, PRLS, and perceptual strength significantly increased as a more medial laryngeal subsite was stimulated and as stimulus force increased. Each of the ten years of age increase was associated with 19% reduction in odds of LAR (aOR = 0.81, 95% CI [0.68, 0.97]; p = 0.022). Male gender was associated with a 55% reduction in odds of LAR (aOR = 0.45, 95% CI [0.23, 0.89]; p = 0.022).

CONCLUSION

LAR elicitation capability decreases in the male gender, aging, and a more lateral subsite. This study provides insight into the pathophysiology of hypo- and hyper-sensitive laryngeal disorders and is paramount to making accurate diagnostic assessments and finding novel treatment options for various laryngological disorders. Laryngoscope, 133:2525-2532, 2023.

A Novel Approach to Severe Chronic Neurogenic Dysphagia Using Pharyngeal Sensory Electrical Stimulation

ABSTRACT

The treatment options for severe chronic neurogenic dysphagia are limited. A patient, after resection of medulla oblongata hemangioblastoma, who failed to respond to 7 mos of traditional dysphagia rehabilitation therapy, was treated with prolonged pharyngeal sensory electrical stimulation for 39 sessions over 57 days. For the first time, this case report showed improvement in hypopharyngeal peak pressure (9.1 vs. 90.8 mm Hg) using high-resolution manometry. Reductions in the penetration and aspiration scale, secretion, and residue of the vallecular and pyriform sinus were verified by videofluoroscopic swallowing study and flexible endoscopic evaluation of swallowing. The Functional Oral Intake Scale score increased from 1 to 6. No adverse event was observed. This case report presented a potential therapeutic protocol for severe chronic neurogenic dysphagia, which might be instructive for clinical practice.

Current approaches to reporting pharyngo-laryngeal secretions

PURPOSE OF REVIEW

Accumulated secretions in the pharynx and larynx are associated with dysphagia, aspiration and pneumonia, as well as increased social, health and economic burden. This article reviews developments in the instrumental reporting of pharyngo-laryngeal secretions over the last 2 years.

RECENT FINDINGS

Although the healthy pharynx and larynx is moist, accumulation of secretions is indicative of abnormality. Using standardized secretion scales allows early identification, quantification of risk in patients, and sensitive monitoring of patients over time. Nonstandardized and subjective secretion reporting is common in recently published research despite the validation of a number of publicly available tools. Research characterizing accumulated secretions has contributed to our understanding of pathophysiology associated with poor secretion management and may inform future treatment studies.

SUMMARY

Routine and standardized reporting of secretions is critical for patient assessment and should be reported in the most standardized way possible. Further research investigating the clinical relevance and treatment of accumulated secretions relies on quantitative pharyngolaryngeal secretions reporting.

Effects of carbonation of liquids on penetration-aspiration and residue management

Objective

Carbonation as a sensory enhancement strategy for prevention of aspiration of thin liquids has not been thoroughly studied. The aim of our study was to examine the effect of carbonation on penetration–aspiration and pharyngeal residue in dysphagia patients using Fiber-Optic Endoscopic Evaluation of Swallowing (FEES) and to identify parameters associated with a response to carbonation.

Methods

A cross-sectional study of patients undergoing FEES in a dysphagia clinic. Patients were offered 100 cc of dyed water. Penetration–aspiration was scored using the penetration–aspiration scale (PAS). Residue was scored using the Yale Pharyngeal Residue Severity Rating Scale (YPR-SRS). Patients with a PAS ≥ 2 for water were subsequently offered 100 cc of carbonated water. PAS, YPR-SRS and residue clearance were compared between thin and carbonated liquids. Multivariate logistic regression analysis was used to identify predictors for good response to carbonation.

Results

84 patients were enrolled, 77.4% males, with diverse dysphagia etiologies (58.3% neurogenic, 11.9% radiation-induced, 23.8% deconditioning-induced, and 6% neck surgery induced). Median PAS was 7 (IQR 4–8) for thin liquids and 4.5 (IQR 2–8) for carbonated liquids (P = 0.0001). YPR-SRS was reduced for carbonated compared to thin liquids in the vallecula (1.58 ± 0.83 vs 1.76 ± 0.93, P = 0.001) and piriform sinuses (1.5 ± 0.87 vs 1.67 ± 0.9, P = 0.002). 31 patients had improvement in PAS with carbonation. Deconditioning as a dysphagia etiology was found to predict good response to carbonation on multivariate logistic regression analysis.

Conclusion

Carbonation may prevent aspiration and improve residue management for some patients with dysphagia for liquids.

Level of evidence

IV.

Adaptation and Validation of the Dynamic Imaging Grade of Swallowing Toxicity for Flexible Endoscopic Evaluation of Swallowing: DIGEST-FEES

Purpose While flexible endoscopic evaluation of swallowing (FEES) is a common clinical procedure used in the head and neck cancer (HNC) population, extant outcome measures for FEES such as bolus-level penetration-aspiration and residue scores are not well suited as global patient-level endpoint measures of dysphagia severity in cooperative group trials or clinical outcomes research. The Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) was initially developed and validated for use during videofluoroscopic evaluations as a way to grade safety, efficiency, and overall pharyngeal swallowing impairment. The purpose of this study was to adapt and validate DIGEST for use with FEES. Method A modified Delphi exercise was conducted for content validation, expert consensus, adaptation, and operationalization of DIGEST-FEES. Three blinded, expert raters then evaluated 100 de-identified post-HNC treatment FEES examinations. Intra- and interrater reliability were tested with quadratic weighted kappa. Criterion validity against the MD Anderson Dysphagia Inventory, Functional Oral Intake Scale, Secretion Severity Scale, and Yale Residue Rating Scale was assessed with Spearman correlation coefficients. Results Interrater reliability was almost perfect for overall DIGEST-FEES grade (κ_w = 0.83) and safety grade (κ_w = 0.86) and substantial for efficiency grade (κ_w = 0.74). Intrarater reliability was excellent for all raters (0.9-0.91). Overall DIGEST-FEES grade correlated with MD Anderson Dysphagia Inventory (r = -.43, p < .0001), Functional Oral Intake Scale (r = -.43, p < .0001), Secretion Severity Scale (r = .47, p < .0001), Yale Vallecular Residue (r = .73, p < .0001), and Yale Pyriform Sinus Residue (r = .65, p < .0001). Conclusion DIGEST-FEES is a valid and reliable scale to describe the severity of pharyngeal dysphagia in patients with HNC. Supplemental Material https://doi.org/10.23641/asha.14642787.

Diagnosis and management of aspiration using fiberoptic endoscopic evaluation of swallowing in a Pediatric Pulmonology Unit

BACKGROUND AND OBJECTIVES

Swallowing disorders lead to chronic lung aspiration. Early detection and treatment of aspiration in children with dysphagia are important to prevent lung damage. Diagnosis of aspiration, which may be silent, requires an instrumental study such as fiberoptic endoscopic evaluation of swallowing (FEES). Despite its usefulness, it is rarely practiced by pediatric pulmonologists. This study aimed to evaluate the feasibility and utility of FEES performed in the pediatric respiratory unit of a tertiary hospital, analyze the clinical characteristics, endoscopic findings and proposed treatments, and identify the factors associated with penetration or aspiration.

METHODS

Medical records of 373 children with suspected aspiration who were referred to the pediatric respiratory unit for FEES were reviewed retrospectively. Clinical characteristics, FEES findings, and the proposed treatments were analyzed.

RESULTS

Laryngeal penetration/aspiration was seen in 47.9% of the patients. The most common associated conditions were neurological disease and prematurity. The most frequently observed endoscopic finding was altered laryngeal sensitivity (36.5%). Intervention was recommended in 54.2% of the patients. Complications were not seen during any of the procedures. The multivariate logistic regression model revealed an independent association between aspiration and alterations in laryngeal sensitivity (odds ratio [OR], 5.68), pharyngeal pooling (OR, 11.47), and post-swallowing food residues (OR, 8.08).

CONCLUSIONS

The FEES procedure performed by pediatric pulmonologists is a reliable method for diagnosing aspiration in children. It can be safely executed by trained pulmonologists, and significant endoscopic signs other than aspiration can guide in the diagnosis and management recommendations.

Endoscopic evaluation of pharyngeal and laryngeal sensation in patients with chronic obstructive pulmonary disease (COPD): A cross-sectional study

OBJECTIVE

To describe and compare the findings of endoscopic sensory assessment in COPD patients and healthy controls.

DESIGN

A prospective cross-sectional study.

SETTING

Otorhinolaryngology outpatient clinic at a university hospital.

PARTICIPANTS

27 adults with COPD and 11 age-matched healthy controls.

MAIN OUTCOME MEASURES

Group differences in light touch endoscopic tests of pharyngeal and laryngeal sensation, controlling for pooled salivary secretions in the pharynx and laryngo-pharyngeal reflux as measured by the Reflux Finding Score (RFS).

RESULTS

A significant difference in laryngeal sensation was found between the study groups (P = .047), with reduced laryngeal sensation in the COPD patients. Additionally, a significant relationship was found between impaired oropharyngeal sensation and the presence of pooled salivary secretions in the pharynx (P = .018), especially in the pyriform sinuses (P = .012). No differences in the frequency of abnormal RFSs were found between groups.

CONCLUSION

Individuals with COPD were significantly more likely to present with impaired laryngeal sensation. Additionally, impaired sensation in the oropharynx was associated with pooled salivary secretions in the pharynx.

Targeting the sensory feedback within the swallowing network-Reversing artificially induced pharyngolaryngeal hypesthesia by central and peripheral stimulation strategies

Pharyngolaryngeal hypesthesia is a major reason for dysphagia in various neurological diseases. Emerging neuromodulation devices have shown potential to foster dysphagia rehabilitation, but the optimal treatment strategy is unknown. Because functional imaging studies are difficult to conduct in severely ill patients, we induced a virtual sensory lesion in healthy volunteers and evaluated the effects of central and peripheral neurostimulation techniques. In a sham-controlled intervention study with crossover design on 10 participants, we tested the potential of (peripheral) pharyngeal electrical stimulation (PES) and (central) transcranial direct current stimulation (tDCS) to revert the effects of lidocaine-induced pharyngolaryngeal hypesthesia on central sensorimotor processing. Changes were observed during pharyngeal air-pulse stimulation and voluntary swallowing applying magnetoencephalography before and after the interventions. PES induced a significant (p < .05) increase of activation during swallowing in the bihemispheric sensorimotor network in alpha and low gamma frequency ranges, peaking in the right premotor and left primary sensory area, respectively. With pneumatic stimulation, significant activation increase was found after PES in high gamma peaking in the left premotor area. Significant changes of brain activation after tDCS could neither be detected for pneumatic stimulation nor for swallowing. Due to the peripheral cause of dysphagia in this model, PES was able to revert the detrimental effects of reduced sensory input on central processing, whereas tDCS was not. Results may have implications for therapeutic decisions in the clinical context.

The prevalence and findings of fibre-optic endoscopic evaluation of swallowing in hospitalised patients with dysphagia

Swallowing disorder or dysphagia is quite common in hospitalised patients. Using fibre-optic endoscopic evaluation of swallowing (FEES) is one of the clinical standards for evaluating swallowing disorder to prevent serious consequences such as aspiration pneumonia. This study aimed to determine the prevalence and the associated risk of dysphagia in hospitalised patients by using FEES finding. We retrospectively analysed the FEES records from the patients who were screened and suspected of swallowing problems by a certified nurse of dysphagia nursing (CNDN). The FEES findings were compared between dysphagia and without dysphagia to evaluate the associated risk of dysphagia. Six-hundred and nine FEES records were analysed. We found dysphagia 76% in patients who suspected swallowing problems by CNDN. FEES was assessed after the subjects had been admitted for 22 days on average. There was no difference in age between dysphagia and without dysphagia participants. However, the advanced age (age > 85 years old) increased the odd of dysphagia 1.18, P = .03. The primary disease of the subjects was mainly cerebrovascular disease (24%) and pneumonia (22%). Abnormal FEES findings including soft palate elevation, velopharyngeal contraction, whiteout, volitional cough, glottis closure during breath holding, cough reflex and presence of secretion in pharynx were found in hospitalised patients with dysphagia. The prevalence of dysphagia was high in hospitalised patients. Hence, screening the swallowing problem by nurse and FEES evaluation is essential to detect and prevent the complication in the patient who has dysphagia.

Fiberoptic Endoscopic Evaluation of Swallowing in Patients with Type 2 Diabetes Who Have Self-Reported Swallowing Difficulties

INTRODUCTION

People with diabetes frequently have gastrointestinal problems and related deglutition disorders.

OBJECTIVE

The aims of the present study are to determine the symptomatic swallowing complaints and to evaluate the functionality of oropharyngeal swallowing in patients with type 2 diabetes mellitus (T2DM) by using the Turkish Eating Assessment Tool-10 (T-EAT-10) and fiberoptic endoscopic evaluation of swallowing (FEES).

METHODS

In this descriptive cross-sectional study, the T-EAT-10 questionnaire was completed by 121 patients with diabetes, and FEES was planned for each individual whose baseline score of the T-EAT-10 was ≥3. Before swallowing trials via samples of nectar-thick consistency, laryngeal sensation and severity of secretion in the hypopharynx were observed. While the swallowing safety was determined using the Penetration-Aspiration Scale (PAS), the Yale Pharyngeal Residue Severity Rating Scale was used to assess the swallowing efficiency.

RESULTS

Of the total participants, 22.3% (n = 27) were found to have abnormal swallowing function (T-EAT-10 ≥3), 27.3% (n = 33) had concomitant neuropathy and 28.1% (n = 34) mentioned a reflux complaint. The results of the multivariate linear regression analysis exposed that the T-EAT-10 score was significantly associated with neuropathy (r = 3.763, p < 0.001) and reflux complaint (r = 2.254, p = 0.031). Of the total FEES-tested subjects (n = 20), 95% (n = 19) had a safe swallowing function (PAS = 1). However, diminished laryngeal sensation, increased secretion and presence of residue revealed that patients with T2DM who have self-reported swallowing difficulties have reduced swallowing efficiency.

CONCLUSIONS

This study has demonstrated that almost 1 out of 4 T2DM patients reported to have swallowing-related problems, and the score of the T-EAT-10 was found to be independently associated with both neuropathy and reflux complaint. FEES results pointed out that swallowing efficiency was relatively reduced in the target population. However, further research is still necessary before obtaining a definitive answer to oropharyngeal swallowing problems in patients with T2DM.

Inter- and Intra-Rater Reliability of Laryngeal Sensation Testing with the Touch Method During Flexible Endoscopic Evaluations of Swallowing

OBJECTIVES

Sensation is an integral component of laryngeal control for breathing, swallowing, and vocalization. Laryngeal sensation is assessed by elicitation of the laryngeal adductor reflex (LAR), a brainstem-mediated adduction of the true vocal folds. During Flexible Endoscopic Evaluations of Swallowing (FEES), the touch method can be used to elicit the LAR to judge laryngeal sensation. Despite the prevalence of this method in clinical practice and research, prior studies have yet to examine inter- and intra-rater reliability.

METHODS

Four speech-language pathologists rated 125 randomized video clips for the presence, absence, or inability to rate the LAR. Fifty percent of video clips were re-randomized and re-rated 1 week later. Raters then created guidelines and participated in formal consensus training sessions on a separate set of videos. Ratings were repeated post-training.

RESULTS

Overall inter-rater reliability was fair (κ = 0.22) prior to training. Pre-training intra-rater reliability ranged from fair (κ = 0.35) to almost perfect (κ = 0.89). Inter-rater reliability significantly improved after training (κ = 0.42, P < .001), though agreement did not reach prespecified acceptable levels (κ ≥ 0.80). Post-training intra-rater reliability ranged from moderate (κ = 0.49) to almost perfect (κ = 0.85).

CONCLUSION

Adequate inter-rater reliability was not achieved when rating isolated attempts to elicit the LAR. Acceptable within-rater reliability was observed in some raters 1 week after initial ratings, suggesting that ratings may remain consistent within raters over a short period of time. Limitations and considerations for future research using the touch method are discussed.

FEES-based assessment of pharyngeal hypesthesia-Proposal and validation of a new test procedure

BACKGROUND

Intact pharyngeal sensation is essential for a physiological swallowing process, and conversely, pharyngeal hypesthesia can cause dysphagia. This study introduces and validates a diagnostic test to quantify pharyngeal hypesthesia.

METHODS

A total of 20 healthy volunteers were included in a prospective study. Flexible endoscopic evaluation of swallowing (FEES) and a sensory test were performed both before and after pharyngeal local anesthesia. To test pharyngeal sensation, a small tube was positioned transnasally in the upper third of the oropharynx with contact to the lateral pharyngeal wall. Increasing volumes of blue-dyed water were injected through the tube, and the latency of swallowing response (LSR) was determined by two independent raters from the endoscopic video recording. Three trials were performed for each administered volume starting with 0.1 mL and increased by 0.1 mL up to 0.5 mL.

KEY RESULTS

The average LSR without anesthesia was 2.24 ± 0.80 s at 0.1 mL, 1.79 ± 0.84 s at 0.2 mL, 1.29 ± 0.62 s at 0.3 mL, 1.17 ± 0.41 s at 0.4 mL, and 1.19 ± 0.52 s at 0.5 mL. With anesthesia applied, the average LSR was 2.65 ± 0.62 s at 0.1 mL, 2.64 ± 0.49 s at 0.2 mL, 2.44 ± 0.65 s at 0.3 mL, 2.10 ± 0.80 s at 0.4 mL, and 2.18 ± 0.85 s at 0.5 mL. LSR was significantly longer following anesthesia at 0.2 mL (t = -3.82; P = .001), 0.3 mL (t = -4.65; P < .000), 0.4 mL (t = -5.77; P < .000), and 0.5 mL (t = -3.49; P = .005).

CONCLUSION AND INFERENCES

Pharyngeal hypesthesia can be quantified with sensory testing using LSR. Suitable volumes to distinguish between normal and impaired pharyngeal sensation are 0.2 mL, 0.3 mL, 0.4 mL and 0.5 mL. Experimentally induced pharyngeal anesthesia represents a valid model of sensory dysphagia.