Normative High-Resolution Pharyngeal Manometry: Impact of Age, Size of System, and Sex on Primary Metrics and Pressure Stability.

There have been many reports of normative pharyngeal swallowing pressures using high-resolution pharyngeal manometry, but there is a fair amount of between-subject variance in reported pressure parameters. The purpose of this study was to put forward normative pharyngeal high-resolution manometry measures across the lifespan and investigate the effects of age, size of system, and sex. High-resolution pharyngeal manometry was performed on 98 healthy adults (43 males) between the ages 21 and 89. Pressure duration, maxima, integral, and within-individual variability metrics were averaged over 10 swallows of 10-ml thin liquid. Multiple linear and logistic regressions with model fitting were used to examine how pharyngeal pressures relate to age, pharyngeal size, and sex. Age was associated with tongue base maximum pressure, tongue base maximum variability, and upper esophageal sphincter-integrated relaxation pressure (F3,92 = 6.69; p < 0.001; adjusted R2 = 0.15). Pharyngeal area during bolus hold was associated with velopharynx integral (F1,89 = 5.362; p = 0.02; adjusted R2 = 0.05), and there was no significant model relating pharyngeal pressures to C2-C4 length (p < 0.05). Sex differences were best described by tongue base integral and hypopharynx maximum variability (χ2 = 10.27; p = 0.006; pseudo R2 = 0.14). Normative data reveal the distribution of swallow pressure metrics which need to be accounted for when addressing dysphagia patients, the importance of pressure interactions in normal swallow, and address the relative stability of swallow metrics with normal aging.

The Manometric Representation of the Upper Esophageal Sphincter During the Resting State: A Descriptive Study.

The upper esophageal sphincter (UES) is the high-pressure zone marking the transition between the hypopharynx and esophagus. There is limited research surrounding the resting UES using pharyngeal high-resolution manometry (HRM) and existing normative data varies widely. This study describes the manometric representation of the resting UES using a clinically accessible method of measurement. Data were obtained from 87 subjects in a normative database of pharyngeal HRM with simultaneous videofluoroscopy. The resting UES manometric region was identified and ten measurement segments of this region were taken throughout the duration of the study using the Smart Mouse function within the manometry software. Intraclass correlation coefficients (ICC) were used to analyze within-subject reliability across measurements. Linear mixed-effects regression models were used to analyze how subject characteristics and manometric conditions influence resting UES pressure. There was excellent within-subject reliability between resting UES mean pressures (ICC = 0.96). In bivariate analysis, there were significant effects of age, number of sensors contained within the resting UES, and preceding swallow volume on mean resting UES pressure. For every 1 unit increase in age, there was a 0.19 unit decrease in resting UES pressure (p = 0.008). For every 1 unit increase in number of sensors contained within the resting UES, there was a 3.71 unit increase in resting UES pressure (p < 0.001). This study presents normative data for the resting UES, using a comprehensive and clinically accessible protocol that can provide standard comparison for the study of populations with swallowing disorders, particularly UES dysfunction, and provides support for UES-directed interventions.

The Natural Swallow: Factors Affecting Subject Choice of Bolus Volume and Pharyngeal Swallow Parameters in a Self-selected Swallow.

Predetermined volumes are used extensively throughout clinical assessment of swallowing physiology, but bolus volumes selected by an individual in their natural swallow can vary greatly from those used in structured assessment. This study aims to identify factors influencing self-selected volume and how the mechanics of self-selected volume swallows differ from predetermined volume swallows. We used pharyngeal high-resolution manometry (HRM) with simultaneous videofluoroscopy to measure swallowing pressures in the velopharynx, hypopharynx, and upper esophageal sphincter (UES). Data were collected from 95 healthy adults during thin liquid swallows of 10 mL and a self-selected comfortable volume. An intraclass correlation coefficient (ICC) was calculated to analyze within-subject self-selected volume reliability. Linear mixed effects regression models were used to examine the association of subject characteristics with self-selected swallow volume and of self-selected volumes on pharyngeal swallowing pressures and timing events. Mean self-selected volume was 16.66 ± 7.70 mL. Increased age (p = 0.002), male sex (p = 0.021), and increased pharyngeal hold area (p = 0.007) were significantly associated with increase in self-selected bolus volume. There was good reliability between subjects' individual swallow volumes (ICC = 0.80). Velopharyngeal maximum pressure and pressure integral, tongue base duration and maximum pressure, UES pre- and post-swallow maximum pressure, and overall pharyngeal contractile integral decreased significantly with self-selected boluses. Understanding a patient's natural swallow volume, and how their natural swallow functions, will be important for designing clinical evaluations that place stress on the patient's natural swallowing mechanics in order to assess for areas of dysfunction.

Pharyngeal Pressure Variability During Volitional Swallowing Maneuvers.

PURPOSE: Within-individual pharyngeal swallowing pressure variability differs among pharyngeal regions in healthy individuals and increases with age. It remains unknown if pharyngeal pressure variability is impacted by volitional swallowing tasks. We hypothesized that pressure variability would increase during volitional swallowing maneuvers and differ among pharyngeal regions depending on the type of swallowing task being performed. METHOD: Pharyngeal high-resolution manometry was used to record swallowing pressure data from 156 healthy participants during liquid (5 cc) or saliva swallows, and during volitional swallowing tasks including effortful swallow, Mendelsohn maneuver, Masako maneuver, or during postural adjustments. The coefficient of variation was used to determine pressure variability of velopharynx, tongue base, hypopharynx, and upper esophageal sphincter regions. Repeated-measures analysis of variance was used on log-transformed data to examine effects of pharyngeal region and swallowing tasks on swallow-to-swallow variability. RESULTS: There was a significant main effect of task with greater pressure variability for the effortful swallow (p = .002), Mendelsohn maneuver (p < .001), Masako maneuver (p = .002), and the head turn (p = .006) compared with normal effort swallowing. There was also a significant main effect of region (p < .01). In general, swallowing pressure variability was lower for the tongue base and upper esophageal sphincter regions than the hypopharynx. There was no significant interaction of task and region (effortful, p = .182; Mendelsohn, p = .365; Masako, p = .885; chin tuck, p = .840; head turn, p = .059; and inverted, p = .773). CONCLUSIONS: Pharyngeal swallowing pressure variability increases in healthy individuals during volitional swallowing tasks. Less stable swallow patterns may result when tasks are less automatic and greater in complexity. These findings may have relevance to swallowing motor control integrity in healthy aging and individuals with neurogenic dysphagia.

Age-Related Functional Reserve Decline Is Not Seen in Pharyngeal Swallowing Pressures.

Purpose Functional reserve represents the difference between an individual's ability to produce a maximum output function and the ability to perform a functional task. Several studies have documented an age-related decrease in functional reserve with oral tongue pressure generation. Whether this pattern is seen in pharyngeal swallowing pressures is unknown. The aim of this study was to investigate pharyngeal functional reserve using high-resolution manometry during normal-effort and effortful swallows. Method Pharyngeal high-resolution manometry was performed on 38 younger healthy individuals (≤ 40 years) and 18 older healthy individuals (≥ 60 years) during normal-effort and effortful water swallows. Pressure metrics included maximum pressure in the velopharynx, tongue base, and hypopharynx, as well as pharyngeal contractile integral and minimum pressure in the upper esophageal sphincter (UES). Repeated-measures analysis of variance was used to determine the effects of swallow task, age, and pharyngeal region on pressure generation. Results Maximum pharyngeal pressures and pharyngeal contractile integral were significantly increased during the effortful swallows compared to normal-effort swallows (p < .001), but there were no interactions between task and age in pharyngeal pressures. In the UES, minimum pressures were significantly elevated in older individuals during effortful swallows compared to normal-effort swallows (p = .007) but did not follow a pattern consistent with reduced functional reserve. Conclusions Healthy individuals increase pharyngeal driving pressures during effortful swallows, without an age-related reduction in the magnitude of pressure increase. Thus, this study did not find evidence for an age-related reduction in pharyngeal functional reserve. The preserved ability to increase pharyngeal pressures during effortful swallowing in aging may support the use of behavioral swallowing interventions in older individuals without neuromuscular conditions. Supplemental Material https://doi.org/10.23641/asha.16606709.

Measurement of Pharyngeal Air Pressure During Phonation Using High-Resolution Manometry.

Purpose The study of air pressure in the vocal tract is essential to understanding vocal function. Changes in vocal tract shape during different phonatory gestures are hypothesized to produce nonuniform air pressure across lower vocal tract locations. Current methods of air pressure measurement, however, are limited to a single location in the anterior oral cavity. The purposes of this study were (a) to assess the feasibility of a novel method of simultaneously measuring phonatory air pressure at multiple locations across the lower vocal tract using high-resolution pharyngeal manometry (HRM) and (b) to compare pressure across locations and among phonatory tasks. Method Two subjects underwent HRM while performing phonatory tasks. A catheter was passed transnasally and air pressure was measured simultaneously at five locations between the velopharyngeal port and the upper esophageal sphincter. Descriptive statistics were calculated for each location by task, and for each task averaged across locations. Results HRM was well tolerated, and air pressures from multiple locations in the lower vocal tract were able to be obtained simultaneously. During vocal tract semi-occlusion tasks, air pressures differed by location. Pressures averaged across locations demonstrated a pattern of increasing pressure with increasing semi-occlusion. Conclusions HRM is feasible for measuring air pressure simultaneously at multiple locations in the lower vocal tract during phonation with high spatial and temporal resolution, providing rich data to augment understanding of vocal function. The high spatial and temporal resolution yielded by this new method, paired with preliminary evidence that pressures change by location as a function of phonatory task, may be useful in future assays exploring differences in lower vocal tract air pressures between normal and disordered populations.

Spectral arc length as a method to quantify pharyngeal high-resolution manometric curve smoothness.

BACKGROUND: Pharyngeal high-resolution manometry (HRM) has emerged over the last decade as a valuable assessment tool for oropharyngeal dysphagia. Data analysis thus far has focused primarily on measures of pressure and duration within key anatomic regions. We apply spectral arc length (SPARC), a dimensionless metric for quantifying smoothness felt to indirectly reflect neuromuscular coordination, as a new method of describing manometric curves. We then use it to distinguish swallows from healthy subjects and those with dysphagia related to stroke. METHODS: Previously collected pharyngeal HRM data from eight subjects with history of stroke and eight age- and sex-matched controls were reviewed. Receiver operating characteristic (ROC) analysis was used to optimize SPARC inputs. SPARC was then computed for the velopharynx, tongue base, hypopharynx, and upper esophageal sphincter (UES), and the values were compared between the two subject groups. RESULTS: Optimized parameter settings yielded an ROC curve with area under the curve (AUC) of 0.953. Mean SPARC values differed between control and stroke subjects for the velopharynx (t = 3.25, p = 0.0058), tongue base (t = 4.77, p = 0.0003), and hypopharynx (t = 2.87, p = 0.0124). Values were similar for the UES (t = 0.43, p = 0.671). CONCLUSIONS: In this preliminary study, SPARC analysis was applied to distinguish control from post-stroke subjects. Considering alternative methods of analyzing pharyngeal HRM data may provide additional insight into the pathophysiology of dysphagia beyond what can be gleaned from measures of pressure and duration alone.

Pharyngeal Swallowing Pressures in Patients with Radiation-Associated Dysphagia.

Dysphagia associated with radiotherapy for head and neck cancer is complex and can be difficult to treat. Videofluoroscopic swallow studies (VFSS) are the current gold-standard instrumented swallow assessment. High-resolution manometry (HRM) is an additional approach that provides objective measurements of swallowing-related pressures in the pharynx and esophagus. This can provide functional information on the pressure gradients underlying bolus propulsion, and is relevant for this patient population, where radiation-related fibrosis can lead to weakness and impaired pressure generation. The purpose of this preliminary study was to describe pharyngeal swallowing pressures in patients with radiation-associated dysphagia (RAD) and late radiation-associated dysphagia (LRAD) using HRM. RAD occurs during and immediately following treatment, whereas LRAD is a more recently described phenomenon in which the patient experiences an onset of dysphagia at least 5 years post-treatment. We performed a retrospective analysis of pharyngeal swallowing pressures from 21 patients with RAD or LRAD and 21 healthy sex/age-matched controls. Patients with RAD or LRAD exhibited decreased swallowing pressure durations throughout the pharynx (p ≤ 0.002), as well as decreased hypopharynx maximum pressure (p = 0.003) and pharyngeal contractile integral ( p < 0.0001). Understanding how pharyngeal pressure generation is altered in patients with a history of radiotherapy can help clinicians form more precise treatment plans.

Swallowing Pressure Variability as a Function of Pharyngeal Region, Bolus Volume, Age, and Sex.

OBJECTIVES: Within-individual movement variability occurs in most motor domains. However, it is unknown how pharyngeal swallowing pressure varies in healthy individuals. We hypothesized that: 1) variability would differ among pharyngeal regions; 2) variability would decrease with increased bolus volume; 3) variability would increase with age; and 4) there would be no sex differences. STUDY DESIGN: Case series. METHODS: We used pharyngeal high-resolution manometry to measure swallowing pressure in the following regions: velopharynx, tongue base, hypopharynx, and upper esophageal sphincter. Data were collected from 97 healthy adults (41 male) aged 21 to 89 years during thin liquid swallows: 2 mL, 10 mL, and participant-selected comfortable volume. Pressure variability was measured using coefficient of variation. Repeated measures analysis of variance was used to assess impacts of region, bolus volume, age, and sex on pressure variability. RESULTS: There was a significant region × volume interaction (P < .001) and significant main effect of age (P = .005). Pressures in the hypopharynx region were more variable than all other regions (P ≤ .028), and pressures in the tongue base region were less variable than all other regions (P ≤ .002) except at 2 mL volumes (P = .065). Swallowing pressure variability was significantly different in the velopharynx and upper esophageal sphincter regions, with comfortable volume and 2 mL swallows having greater variability than 10 mL swallows (P ≤ .026). Pressure variability significantly increased with increasing age (P = .002). There were no effects of sex on pressure variability (P ≥ .15). CONCLUSION: Pharyngeal swallowing pressure variability differs according pharyngeal region, volume, and age but not sex. Abnormal swallowing pressure variability may reflect deviations in motor control in persons with swallowing impairment, and results from this study can be used as normative data for future investigations evaluating swallowing pressure generation. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E52-E58, 2021.

Post-stroke Dysphagia: Recent Insights and Unanswered Questions.

PURPOSE OF REVIEW: We explored themes in recent post-stroke dysphagia literature, focusing on the following questions: (1) What does post-stroke dysphagia look like?; (2) Who gets post-stroke dysphagia?; (3) What are the consequences of post-stroke dysphagia?; and (4) How can we improve treatment of post-stroke dysphagia? RECENT FINDINGS: There have been several improvements in quantitative descriptions of swallowing physiology using standard and new evaluation techniques. These descriptions have been correlated with lesion locations, and several factors can predict development of post-stroke dysphagia and its sequelae. Novel treatment paradigms have leveraged post-stroke neuroplastic improvements using neurostimulation and biofeedback techniques. Despite recent findings, the field is limited by lack of standardization and unanswered questions on rehabilitation variables. Our improved understanding of post-stroke dysphagia will enhance our ability to prevent, identify, and treat it. Future work should be grounded in swallowing physiology and continue refining treatments, particularly in the acute stage.

Pressure abnormalities in patients with Zenker's diverticulum using pharyngeal high-resolution manometry.

OBJECTIVES: Zenker's diverticulum is associated with reduced cricopharyngeal compliance and abnormal intrabolus pressure. However, it is unclear how the pharynx compensates for these deficits. Developments in manometric technology have improved our ability to capture pharyngeal pressure events. This study aims to describe the pharyngeal-upper esophageal sphincter (UES) pressure profile during swallowing in patients with Zenker's diverticulum. METHODS: High-resolution manometry was performed on 11 patients with symptomatic Zenker's diverticulum and 11 age- and sex-matched healthy controls during 10 mL liquid swallowing tasks. Pharyngeal and UES pressure magnitudes, durations, and integrals were compared between patients and controls using independent t tests. Other manometric parameters, including residual UES pressure at the time of maximum tongue base pressure and pharyngeal-UES pressure gradient, were also evaluated. A case example using three-dimensional high-resolution manometry is presented. RESULTS: Compared with healthy controls, patients with Zenker's diverticulum exhibited pressure abnormalities in the UES region. While baseline and pre-opening maximum pressures were not different, residual pressures were elevated (P = .001). Pharyngeal-UES pressure gradients did not differ between the two groups. CONCLUSION: This study used high-resolution manometry to characterize pharyngeal pressure dynamics in patients with Zenker's diverticulum. The changes occurring at the cricopharyngeus appear to result in persistent UES pressurization during UES opening, rather than high tonic resting pressure. Pharyngeal-UES pressure gradients, critical to bolus passage, were also preserved in this patient population. LEVEL OF EVIDENCE: 3b.

Perceived Professional and Institutional Factors Influencing Clinical Adoption of Pharyngeal High-Resolution Manometry.

Purpose We assessed experienced clinicians' perceptions of benefits and drawbacks to the clinical adoption of pharyngeal high-resolution manometry (HRM). This article focuses on the professional and institutional factors that influence the clinical adoption of pharyngeal HRM by speech-language pathologists (SLPs). Method Two surveys (closed- and open-ended questions) and a series of focus groups were completed with SLP members of both the American Speech-Language-Hearing Association and the Dysphagia Research Society (DRS). Transcripts were inductively coded for emergent themes. Results Thirteen SLPs were recruited to attend focus group sessions at the American Speech-Language-Hearing Association. Eighty-seven SLPs responded to the DRS open-set response survey. Two additional focus groups of 11 SLPs were convened at the DRS meeting. Conventional content analysis revealed overall SLP enthusiasm for the clinical use of HRM, with some concerns about the technology adoption process. The following themes related to the professional and institutional factors influencing clinical adoption were identified: (a) scope of practice, (b) access, (c) clinical workflow, and (d) reimbursement. Conclusion These data serve to elucidate the most salient factors relating to the clinical adoption of pharyngeal HRM into routine speech-language pathology clinical practice. While enthusiasm exists, a variety of systems-level issues must be addressed to support this process.

High-resolution manometry and swallow outcomes after vocal fold injection medialization for unilateral vocal fold paralysis/paresis.

BACKGROUND: Injection medialization is performed to improve glottic closure, thereby airway protection. Overall objective to determine if unilateral injection medialization changes glottal area with concomitant adjustments in penetration/aspiration scale (PAS) scores and pharyngeal high-resolution manometry (HRM) parameters. METHODS: Enrolled 17 adults with unilateral vocal fold paralysis/paresis and aspiration/penetration. Fiberoptic endoscopic evaluation of swallowing and pharyngeal HRM completed at (1) baseline (within 1 week before injection), (2) postinjection (within 1 week post injection), and (3) 1-month postinjection. Comparisons between time points for PAS scores, glottal area, pharyngeal pressure, and timing. RESULTS: No significant differences in normalized glottal area. No significant differences in PAS scores, for any consistency. Significantly increased rate of mesopharynx pressure rise and maximum pressure at 1 month postinjection (P = .01 and .02, respectively) compared to baseline. Significant decrease in mesopharynx integral from baseline to 1 week postoperative (P = .03). CONCLUSION: Findings suggest unilateral vocal fold injection medialization had limited effect on swallow function.

Correlates of Early Pharyngeal High-Resolution Manometry Adoption in Expert Speech-Language Pathologists.

Pharyngeal high-resolution manometry (HRM) is at a point of entry into speech-language pathologist (SLP) clinical practice. However, the demographic characteristics of SLPs who are early adopters of HRM are unclear; perspectives of early adopters may shape how the technology is received by the field at large. We hypothesized that younger SLPs, those working in outpatient settings, those with a strong knowledge base in HRM, and those with experience in other types of instrumentation are more likely to have interest in adopting HRM. We surveyed the population of board-certified SLPs (BCS-S; n = 262) with a 33% response rate (n = 78). Firth logistic regression was used to determine differences in those expressing interest in adopting HRM into future practice (n = 28) and those who did not (n = 45) from the analytic sample of 73 respondents. The best fitting model predicted that SLPs: (1) with training in more types of instrumentation; and (2) believing they could explain the HRM procedure to a patient were more likely to plan to adopt pharyngeal HRM into regular clinical practice. Experience with a variety of instrumentation techniques may encourage SLPs to use new forms of technology. Knowledge of early adopter demographics will allow for development of targeted trainings and determination of HRM implementation barriers. Identification of a clinician sub-group more likely to adopt other new technologies in the future may also be possible.

SLP-Perceived Technical and Patient-Centered Factors Associated with Pharyngeal High-Resolution Manometry.

High-resolution manometry (HRM) objectively measures swallowing-related pressures in the pharynx and esophagus. It has been used in many research applications, but it is unclear how HRM is perceived amongst speech-language pathologists (SLP) as it enters into clinical practice. The purpose of this study was to explore SLP perceptions of clinical HRM use. Based on qualitative data collected at four focus groups held at two national conferences and a survey based on open-ended questions, we found broad consensus among those queried regarding how HRM's objective and targeted data could enhance diagnosis and drive treatments. However, we found less consensus among SLPs regarding which patients may and may not benefit, as well as when in the clinical process HRM would best supplement existing technologies, showing a need for further research. These findings highlight how SLPs can be motivated to adopt new clinical technologies if they see a patient-centered benefit and underscore the need for continued SLP education on pharyngeal HRM.

Vocalization development in common marmosets for neurodegenerative translational modeling.

Objectives In order to facilitate the study of vocalizations in emerging genetic common marmoset models of neurodegenerative disorders, we aimed to analyze call-type changes across age in a translational research environment. We hypothesized that acoustic parameters of vocalizations would change with age, reflecting growth of the vocal apparatus and a maturation of control needed to make adult-like calls. Methods Nineteen developing common marmosets were longitudinally video- and audio-recorded between the ages of 1-149 days in a naturalistic setting without any vocalization elicitation protocol. Vocalizations were coded for call type (cry, tsik, trill, phee, and trill-phee) and analyzed for duration (sec), minimum and maximum frequency (Hz), and bandwidth (Hz). Mixed model linear regressions were performed to assess the effects of age on call parameters listed above for each call type. Results Cries decreased in duration (P = 0.038), maximum frequency (P = 0.047), and bandwidth (P = 0.023) with age. Tsik calls decreased in duration (P = 0.002) and increased in minimum frequency (P = 0.004) and maximum frequency (P = 0.005) with age. Trill calls increased in duration (P = 0.003), and trillphee bandwidth (P = 0.031) decreased with age. Discussion Our results demonstrate that development of common marmoset vocalizations is call type dependent and that changes in acoustic parameters can be detected without complex vocalization elicitation paradigms or specialized audio recording equipment. Thus, we demonstrate the feasibility of a naturalistic protocol to collect and objectively analyze marmoset vocalizations longitudinally. This approach may be useful for studying vocal communication deficits in genetic models of neurodegenerative disorders.

Effect of Body Position on Pharyngeal Swallowing Pressures Using High-Resolution Manometry.

The effect of body position and gravitational pull on the complex pressure-driven process of pharyngeal swallowing remains unknown. Using high-resolution manometry (HRM), this study aims to identify positional adaptations of pharyngeal physiology by evaluating swallowing pressure patterns in a series of inverted body positions. Ten healthy adults each underwent swallowing tasks with pharyngeal HRM at six body positions using an inversion table (0°[upright], 45°, 90°[supine], 110°, 135°, and 180°[fully inverted]). Repeated measures ANOVA was used to assess impact of position on pressure parameters, and pharyngeal-UES pressure gradients translate. Velopharyngeal pressures varied by position (P < 0.001), with significantly higher pressures generated with inversion ≥90°, compared with upright and 45°. Change in position did not significantly affect common mesopharyngeal pressures or swallowing pressure durations. UES valving mechanisms were preserved during inversion, with subtle variations observed in integral pressures (P = 0.011). Pharyngeal-UES pressure gradients changed with position (P < 0.01), increasing with inversion > 90° compared to upright and 45°. Mechanisms of deglutition may differ with position and relative direction of gravity, particularly when at > 45° inclination. Increased palatal pressure is generated in the upside-down position to achieve nasopharyngeal closure and prevent regurgitation. While other classically measured pressures may not consistently differ with positioning, many individuals exhibit adaptations in pressure gradients when inverted, likely due to a combination of changes in pharyngeal driving force and UES opening mechanisms. Identification of these changes, relative to position, further builds on our understanding of the adaptability of the pharyngeal swallowing system.

Methods for measuring swallowing pressure variability using high-resolution manometry.

Any movement performed repeatedly will be executed with inter-trial variability. Oropharyngeal swallowing is a complex sensorimotor action, and swallow-to-swallow variability can have consequences that impact swallowing safety. Our aim was to determine an appropriate method to measure swallowing pressure waveform variability. An ideal variability metric must be sensitive to known deviations in waveform amplitude, duration, and overall shape, without being biased by waveforms that have both positive and sub-atmospheric pressure profiles. Through systematic analysis of model waveforms, we found a coefficient of variability (CV) parameter on waveforms adjusted such that the overall mean was 0 to be best suited for swallowing pressure variability analysis. We then investigated pharyngeal swallowing pressure variability using high-resolution manometry data from healthy individuals to assess impacts of waveform alignment, pharyngeal region, and number of swallows investigated. The alignment that resulted in the lowest overall swallowing pressure variability was when the superior-most sensor in the upper esophageal sphincter reached half its maximum pressure. Pressures in the tongue base region of the pharynx were least variable and pressures in the hypopharynx region were most variable. Sets of 3 - 10 consecutive swallows had no overall difference in variability, but sets of 2 swallows resulted in significantly less variability than the other dataset sizes. This study identified variability in swallowing pressure waveform shape throughout the pharynx in healthy adults; we discuss implications for swallowing motor control.

Pharyngeal swallowing pressures in the base-of-tongue and hypopharynx regions identified with three-dimensional manometry.

OBJECTIVES: This study aims to use three-dimensional (3D) high-resolution manometry to identify circumferential pressure patterns generated within the asymmetrical base-of-tongue and hypopharynx regions of the pharynx during deglutition. STUDY DESIGN: Case series. METHODS: Radial pressures in the regions of interest were evaluated during swallowing events in 12 healthy subjects using 3D high-resolution manometry. RESULTS: Repeated measures analysis of variance revealed asymmetrical pharyngeal clearance pressures in the base-of-tongue and hypopharynx regions during swallowing. A significant main effect of direction on pressure was found at the time point of average maximum pressure (P < 0.001) and for pressure integral (P < 0.001), with pressure primarily generated from the posterior direction. An interaction was noted between direction and location when comparing maximum directional pressures, regardless of time (P =0.045), highlighting the differences in anterior pressure production between regions. In contrast to the high posterior pressures produced in the base-of-tongue region, an anteroposterior dominant pressure pattern was observed in the hypopharynx. Pressure waveform complexity in the hypopharynx also is likely attributed to activity in the anterior and posterior directions. Symmetrical pressure generation was observed during intrabolus flow within the hypopharynx. CONCLUSION: This study shows that pressure is asymmetrically generated in the base-of-tongue and hypopharynx regions during swallowing of a 10-mL bolus, reflecting the complex anatomy within the pharynx. Understanding of these complex pressure patterns aids in the interpretation of high-resolution manometry and can help guide further study in the clinical assessment and treatment of pharyngeal pathology. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1989-1995, 2017.

Expiratory muscle strength training evaluated with simultaneous high-resolution manometry and electromyography.

OBJECTIVE: To examine feasibility of a simultaneous high-resolution pharyngeal manometry (HRM) and electromyography (EMG) experimental paradigm to detect swallowing-related patterns of palatal, laryngeal, and pharyngeal muscle activity during expiratory training. STUDY DESIGN: Technical report. METHODS: Simultaneous HRM, surface submental, and intramuscular EMG were acquired in two healthy participants during five tasks: 10-cc water swallow, maximum expiratory pressure (MEP) testing, and expiratory muscle strength training (EMST) at three pressure levels (sham, 50%, and 75% MEP). RESULTS: Experimental conditions were feasible. Velopharyngeal closing pressure, palate EMG activity, and pharyngeal EMG activity increased as expiratory load increased. In contrast, thyroarytenoid EMG activity was low during the expiratory task, consistent with glottic opening during exhalation. Submental EMG patterns were more variable during expiratory tasks. Intraluminal air pressures recorded with HRM were correlated with measured expiratory pressures and target valve-opening pressures of the EMST device. CONCLUSION: Results suggest that a simultaneous HRM/EMG/EMST paradigm may be used to detect previously unquantified swallowing-related muscle activity during EMST, particularly in the palate and pharynx. Our approach and initial findings will be helpful to guide future hypothesis-driven studies and may enable investigators to evaluate other muscle groups active during these tasks. Defining mechanisms of action is a critical next step toward refining therapeutic algorithms using EMST and other targeted treatments for populations with dysphagia and airway disorders. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:797-804, 2017.