Hyoid Excursion Research Articles

Translation of Clinical Dysphagia Scales for Use in Translational Studies

Videofluoroscopy is the gold standard for clinical measurement of swallow disorders (dysphagia). Patients are presented with foods and liquids of varying consistencies in order to evaluate the risk of aspiration. The Modified Barium Swallow Impairment Profile (MBSImP) was developed in 2008 and has since become the primary tool to define the degree of dysphagia impairment. In order to determine the utility of the MBSImP in animals with cervical spinal cord injury, animals were presented with tuna water and pate cat food laced with 40% barium sulfate by volume. Data was collected using a miniature c‐arm collecting at 30 frames per second, and exams were performed pre and post cervical spinal cord injury. Out of the 17 components scored on the MBSImP, only 10 components are usable for animals. Additional components/variables are needed due to their anatomical and physiological differences. More specifically, the pharyngeal phase of the swallow in cats shows a threshold in the pharyngeal distention before a full swallow is completed as well as numerous “rocking” motions to transport the bolus posteriorly from the oral cavity. Another difference shows that component 9 (Anterior Hyoid Excursion) is harder to detect due to the slight displacement of the hyoid. However, we did determine that penetration and aspiration could be reliably detected post‐injury using the 30‐frames per second recording. These results support the use of clinical techniques; however, the addition of continuous variables would assist in the measurement of small changes across time.Support or Funding InformationThis work was supported by NIH grant NS110169 and the Craig H. Neilsen Foundation Pilot Research Grant 546714.

Measuring Hyoid Excursion Across the Life Span: Anatomical Scaling to Control for Variation.

Purpose A method for controlling for sex-based differences in measures of hyoid movement using an internal anatomical scalar has been validated in young healthy individuals. Known anatomical changes with aging necessitate validation of this methodology in a mixed-age sample. The primary aim of this study was to validate a method for controlling for sex-based differences in measures of hyoid movement across the life span. Measurement error as a potential source of variability was addressed to inform best practice recommendations. Method Two distinct data sets previously collected using identical protocols were combined for this study to achieve a data set of young (< 40 years) and older (> 65 years) healthy adults. Data included videofluoroscopic swallow studies with three swallow trials each of 5 and 20 ml thin liquid barium. Previously reported methodology was replicated to validate the use of an anatomical scalar for measuring hyoid excursion in this sample. Hyoid movement was measured using 2 methods (rest-to-peak displacement and peak only) in 3 planes of movement (anterior, superior, and hypotenuse), was expressed in millimeters and individually scaled units relative to C4, and normalized using the C2-C4 vertebral distance. Mixed-model repeated-measures analyses of variance were run with each of the 6 hyoid measures as the dependent variable (in both millimeters and C2-C4 units), within-subject factors of sex and bolus volume, and a between-subjects factor of age group. We predicted that the C2-C4 scalar would adequately control for sex-based differences across age groups. Results Significant differences in absolute hyoid movements (millimeters) were observed by sex, bolus volume, and age group. When measured in %C2-C4 units, all differences between males and females were neutralized. Significant differences between 5- and 20-ml boluses were found for all peak position measures. Significant differences between young and older individuals were found for all peak position measures. Conclusion Expressing hyoid excursion as a percentage of the C2-C4 distance appears valid for use across the life span. Peak position is preferable over displacement measures for quantifying hyoid excursion for research and clinical purposes.

Hyoid excursion during the swallow in stroke survivors

Purpose: To examine whether duration, distance or velocity of hyoid excursion is associated with aspiration during the swallow in post-stroke survivors. Method: Duration, distance and velocity of hyoid excursion were calculated using videofluoroscopic swallowing examinations (VFSEs) of 39 post-stroke survivors. Statistical comparisons were made by two-way repeated measures analysis of variance (ANOVA) with between subject variable being aspirators and non-aspirators, and within subject variable being bolus volume (5 ml and 10 ml). Significance level was set as p<0.05. Results: The duration of hyoid excursion in aspirators was significantly slower than in non-aspirators. There were no significant differences in hyoid velocity or distance between aspirators and non-aspirators. Conclusion: Slower hyoid excursion duration may put stroke survivors at risk of aspiration. It is necessary for the clinician to design the intervention strategies to compensate for or rehabilitate from slow hyoid excursion in stroke survivors.

Coordination of tongue pressure production, hyoid movement, and suprahyoid muscle activity during squeezing of gels

ObjectiveThe aim of this study was to evaluate tongue movement and its biomechanical effects during squeezing, one of the oral strategies for processing soft foods, by tongue pressure sensors, videofluorography, and surface electromyography. DesignFifteen healthy men (mean age, 31.0 ± 4.1 years) without dysphagia were recruited. A 0.1-mm-thick pressure sensor sheet with five measuring points, videofluorography, and surface electromyography were used for synchronous measurements of tongue pressure, hyoid movement, and suprahyoid muscles activity, respectively, while squeezing 5 mL of gels. Amplitude, duration, area, and their sequential order during initial squeezing were analyzed. Differences in hyoid position at the onset, peak, and offset of hyoid movement were also analyzed. ResultsAt the beginning of initial squeezing, tongue pressure at the middle area of the hard palate, hyoid movement, and suprahyoid muscle activity appeared simultaneously, followed by tongue pressure at the anterior area and then at the posterior area. When the hyoid was in an elevated position, the amplitude of suprahyoid muscle activity and tongue pressure peaked. At the end of initial squeezing, the hyoid position at the offset of hyoid excursion was superior to that at the onset. All evaluation items of tongue pressure, hyoid movement, and suprahyoid muscle activity were modulated according to the texture of gels. ConclusionsDuring initial squeezing, tongue pressure, hyoid movement, and suprahyoid muscle activity were coordinated while being modulated by the food texture. At the end of initial squeezing, the hyoid was maintained in an elevated position, which might be beneficial for subsequent squeezing.

Temporal characteristics of laryngeal penetration and aspiration in stroke patients

Despite the importance of understanding penetration-aspiration (PA) in patients with stroke, the pathophysiology of PA remains unclear. This study aimed to investigate the temporal characteristics of PA in post-stroke patients in terms of the timing of the PA event and hyolaryngeal incoordination. Fifty-eight swallows (38 stroke patients), showing PA when swallowing a thin liquid, were included. The timing of PA was classified kinematically as before or during the swallow. The movement sequence of vertical laryngeal elevation, horizontal hyoid excursion, and epiglottic rotation were compared with healthy controls. Spatiotemporal measurements, videofluoroscopic dysphagia scale parameters were compared between subgroups. Thirteen swallows (22.4%) were classified as PA before the swallow and 45 were classified as PA during the swallow (77.6%). Among the PA during the swallow, 26 (57.8%) swallows exhibited abnormal sequences of hyolaryngeal movements and 19 (42.2%) swallows showed normal sequences of hyolaryngeal movements compared with healthy controls. The onset time of horizontal hyoid excursion (P = 0.028), the time to maximal horizontal hyoid excursion (P = 0.010), and maximal epiglottic rotation (P = 0.030) were significantly more delayed in the PA during the swallow group than in the PA before the swallow group. In the swallows with abnormal sequential movements, the onset of horizontal hyoid excursion occurred significantly later than the onset of epiglottic rotation (P < 0.001). Pyriform sinus residue was observed significantly more often in the swallows with abnormal sequences (P = 0.030) than in the swallows with normal sequences. The timing of PA can be classified as before and during the swallow with significantly different temporal characteristics. The horizontal movement of hyoid is the most important factor associated with the pathophysiology of PA in stroke patients.

Swallow Screen Associated With Airway Protection and Dysphagia After Acute Stroke

ObjectiveThe goal was to examine the outcomes of an existing swallow screen protocol in comparison to results from a formal videofluoroscopic protocol. DesignProspective cohort study. SettingAcute hospital. ParticipantsPatients after acute stroke (N=48). InterventionsNot applicable. Main Outcome MeasuresThe Johns Hopkins Hospital Brain Rescue Unit 3 oz Swallow Screen was implemented by nursing staff upon admission. Videofluoroscopy was conducted within 72 hours of diagnostic neuroimaging and initial swallow screen. Predictive values of the bedside swallow screen (pass/fail) for clinical judgment of dysphagia on videofluoroscopy (presence/absence) were calculated. Overall impairment scores from the Modified Barium Swallowing Impairment Profile were analyzed with respect to swallow screen results. ResultsThirteen participants failed the swallow screen, and 35 passed. Of the 35 patients who passed the swallow screen, 15 were clinically diagnosed with dysphagia on videofluoroscopy. Although pass/fail of the swallow screen was not a significant predictor of presence/absence of dysphagia, a logistic regression model including components of Laryngeal Elevation, Laryngeal Vestibule Closure, and Anterior Hyoid Excursion, and sex was statistically significant for swallow screen outcome. ConclusionThe results of this study suggest that a swallow screen of aspiration risk can identify patients with the most need for videofluoroscopic evaluation and dysphagia management. Additionally, patients who fail a swallow screen are more likely to present with physiologic impairments related to airway protection on videofluoroscopy.

Mapping acute lesion locations to physiological swallow impairments after stroke.

Dysphagia is a common deficit after a stroke, and it is frequently associated with pneumonia, malnutrition, dehydration, and poor quality of life. It is not yet fully clear which brain regions are directly related to swallowing, and how lesions affect swallow physiology. This study aimed to assess the statistical relationship between acute stroke lesion locations and impairment of specific aspects of swallow physiology. We performed lesion symptom mapping with 68 retrospectively recruited, acute, first-ever ischemic stroke patients. Lesions were determined on diffusion weighted MRI scans. Post-stroke swallow physiology was determined using the Modified Barium Swallow Study Impairment Profile (MBSImP©™). The relationship between brain lesion location and 17 physiological aspects of swallowing were tested using voxel-based and region-based statistical associations corrected for multiple comparisons using permutation thresholding. We found that laryngeal elevation, anterior hyoid excursion, laryngeal vestibular closure, and pharyngeal residue were associated with lesioned voxels or regions of interests. All components showed distinct and overlapping lesion locations, mostly in the right hemisphere, and including cortical regions (inferior frontal gyrus, pre- and postcentral gyrus, supramarginal gyrus, angular gyrus, superior temporal gyrus, insula), subcortical regions (thalamus, amygdala) and white matter tracts (superior longitudinal fasciculus, corona radiata, internal capsule, external capsule, ansa lenticularis, lenticular fasciculus). Our findings indicate that different aspects of post-stroke swallow physiology are associated with distinct lesion locations, primarily in the right hemisphere, and primarily including sensory-motor integration areas and their corresponding white matter tracts. Future studies are needed to expand on our findings and thus, support the development of a neuroanatomical model of post-stroke swallow physiology and treatment approaches targeting the neurophysiological underpinnings of swallowing post stroke.

Longitudinal Kinematic Evaluation of Pharyngeal Swallowing Impairment in Thyroidectomy Patients.

The aim of this study was to assess pharyngeal swallowing impairments in thyroidectomy patients and to delineate the contributory kinematic components. Forty consecutive patients (mean age = 47.33years) and fourteen age- and sex-matched heathy adult volunteers (mean age = 42.64years) participated in this study. A videofluoroscopic swallowing study (VFSS) was performed 1day prior to surgery, and at 1week and 3months post-surgery. VFSS images were evaluated using the Modified Barium Swallowing Impairment Profile (MBSImp). Kinematic and temporal aspects of swallowing were characterized by measurement of maximum hyoid and laryngeal excursion, pharyngeal transit duration, laryngeal response duration (LRD), and laryngeal closure duration at each three time-points. At 1week post-surgery, only pharyngeal impairment was significantly deteriorated than pre-surgery (p = 0.001). However, at 3months, a significant improvement was observed to pre-surgery level (p = 0.01). Post-surgery, maximum hyoid excursion was significantly reduced in patients compared controls (p = 0.001). Although the maximal distance of the hyoid and the laryngeal excursion was shorter than before surgery, laryngeal excursion at all three time-points was similar to that of controls. At all three time-points, LRD was significantly longer in patients than in controls (p = 0.01). Following thyroidectomy, pharyngeal aspects of swallowing as measured by the MBSImp and kinematic aspects of swallowing were reduced with incomplete recovery at 3months. These exploratory data may guide decision regarding management of pharyngeal swallowing impairment with patients undergoing total thyroidectomy.

Architecture of the Suprahyoid Muscles: A Volumetric Musculoaponeurotic Analysis.

Suprahyoid muscles play a critical role in swallowing. The arrangement of the fiber bundles and aponeuroses has not been investigated volumetrically, even though muscle architecture is an important determinant of function. Thus, the purpose was to digitize, model in three dimensions, and quantify the architectural parameters of the suprahyoid muscles to determine and compare their relative functional capabilities. Fiber bundles and aponeuroses from 11 formalin-embalmed specimens were serially dissected and digitized in situ. Data were reconstructed in three dimensions using Autodesk Maya. Architectural parameters were quantified, and data were compared using independent samples t-tests and analyses of variance. Based on architecture and attachment sites, suprahyoid muscles were divided into 3 groups: anteromedial, superolateral, and superoposterior. Architectural parameters differed significantly (p < .05) across muscles and across the 3 groups, suggesting differential roles in hyoid movement during swallowing. When activated simultaneously, anteromedial and superoposterior muscle groups could work together to elevate the hyoid. The results suggest that the suprahyoid muscles can have individualized roles in hyoid excursion during swallowing. Muscle balance may be important for identifying and treating hyolaryngeal dysfunction in patients with dysphagia.

Effects of neuromuscular electrical stimulation on swallowing and the velocity of hyolaryngeal excursion in post-stroke dysphagia

Objective To observe the effect of neuromuscular electrical stimulation (NMES) at different intensities on functional swallowing and the velocity of hyolaryngeal excursion in post-stroke dysphagia. Methods Thirty stroke survivors with dysphagia were randomly divided into a control group, an NMES group and an intensive NMES group, each of 10. All 3 groups received conventional swallowing training, while the patients in the NMES group also received NMES at 30~80 Hz in an intensity of ≤25 mA once a day and those in the intensive NMES group received it twice a day. Before, as well as 2 and 4 weeks after the treatment, video fluoroscopy when swallowing pap was used to determine the superior and anterior excursion distances of the hyoid and larynx and the excursion′s duration and the corresponding velocity. A water drinking test (WDT) was also administered, and dysphagia severity scale (DSS) and penetration-aspiration scale (PAS) ratings were assessed. Results After the treatment, significant improvement was observed in the average WDT, DSS and PAS scores of all three groups compared to before the treatment. The average WDT score of the intensive NMES group was significantly better than that of the control group after 2 weeks of treatment. After 2 and 4 weeks of treatment, the average DSS of the intensive NMES group was significantly better than that of the control group, while the intensive NMES group′s average PAS score was significantly better than those of both of the other groups. The average anterior hyoid excursion velocity of the intensive NMES group was significantly faster than those of the other two groups after both 2 and 4 weeks of treatment. Pearson correlation analysis indicated that the PAS score was significantly correlated with the anterior hyoid excursion velocity. Conclusion Two NMES sessions a day are superior to only one session in improving functional swallowing after stroke. It better promotes quick movement of the body parts involved. Key words: Neuromuscular electrical stimulation; Dysphagia; Penetration-aspiration scale; Videofluoroscopy; Stroke

Tongue pressure production and hyoid excursion during squeezing and swallowing jelly

Tongue pressure production and hyoid excursion during squeezing and swallowing jelly

The Speed of the Hyoid Excursion in Normal Swallowing

Purpose: To examine the speed of hyolaryngeal excursion in different age and gender groups during normal swallowing. Methods: Temporal and biomechanical measurements of hyolaryngeal excursion were calculated using videofluoroscopic swallowing examinations (VFSEs) of 37 healthy individuals. Statistical comparisons were made by two-way repeated analysis of variance (ANOVA) with between subject variables being age and gender, and within subject variable being bolus volume (5 mL and 10 mL thin liquids). Significance level was set as p<0.025. Results: The speed of hyoid excursion in older populations was significantly slower than in younger ones. There was no gender or bolus volume difference or interaction in the speed of hyoid excursion. Conclusions: Slower hyoid excursion may put older populations at higher risk for aspiration in case of illness or accident. The preventive approach is essential.

Impact of Compliance on Dysphagia Rehabilitation in Head and Neck Cancer Patients: Results from a Multi-center Clinical Trial.

A 5-year, 16-site, randomized controlled trial enrolled 170 HNC survivors into active (estim+swallow exercise) or control (sham estim+swallowing exercise) arms. Primary analyses showed that estim did not enhance swallowing exercises. This secondary analysis determined if/how patient compliance impacted outcomes. A home program, performed 2 times/day, 6days/week, for 12weeks included stretches and 60 swallows paired with real or sham estim. Regular clinic visits ensured proper exercise execution, and detailed therapy checklists tracked patient compliance which was defined by mean number of sessions performed per week (0-12 times) over the 12-week intervention period. "Compliant" was defined as performing 10-12 sessions/week. Outcomes were changes in PAS, HNCI, PSS, OPSE, and hyoid excursion. ANCOVA analyses determined if outcomes differed between real/sham and compliant/noncompliant groups after 12weeks of therapy. Of the 170 patients enrolled, 153 patients had compliance data. The mean number of sessions performed was 8.57/week (median=10.25). Fifty-four percent of patients (n=83) were considered "compliant." After 12weeks of therapy, compliant patients in the sham estim group realized significantly better PAS scores than compliant patients in the active estim group (p=0.0074). When pooling all patients together, there were no significant differences in outcomes between compliant and non-compliant patients. The addition of estim to swallowing exercises resulted in worse swallowing outcomes than exercises alone, which was more pronounced in compliant patients. Since neither compliant nor non-compliant patients benefitted from swallowing exercises, the proper dose and/or efficacy of swallowing exercises must also be questioned in this patient population.

ゼリー嚥下時の舌圧発現様相と舌骨移動との関係

ゼリー嚥下時の舌圧発現様相と舌骨移動との関係

Effects of Age and Bolus Volume on Velocity of Hyolaryngeal Excursion in Healthy Adults.

Reduced movement velocity has been identified as a risk marker for movement impairment in older adults. Hyolaryngeal excursion is a key movement feature of normal swallowing function which is known to change with age and other extrinsic variables such as bolus volume. However, velocity of hyolaryngeal excursion has received limited attention in the literature on normal or abnormal swallowing. This study evaluated the effects of age and bolus volume on the velocity of hyoid and laryngeal excursion during swallowing in healthy adults. Forty-four healthy volunteers were grouped into three age bands (young: 20-35 years, middle age: 36-55 years, older: 56 ≥ years). All subjects swallowed 5 and 20 mL of thin liquid during fluoroscopic recording. Fluoroscopic images were extracted for each swallow representing the onset and maximum excursion positions of the hyoid and larynx. Superior and anterior excursion distance (excursion magnitude) and the time difference between rest and maximum excursion (excursion duration) were calculated. Velocity was calculated as a ratio of distance over time. Superior hyoid excursion magnitude was significantly increased for the 20 mL volume. Anterior laryngeal excursion magnitude was also significantly increased for the 20 mL volume. No kinematic duration measure demonstrated significant change across age or bolus conditions. Superior hyoid excursion velocity was significantly faster for the 20 mL volume. Superior and anterior laryngeal excursion velocity were significantly faster for the 20 mL volume only in the older group. Results of this study indicate that magnitude and velocity of hyoid and laryngeal excursion vary with age and volume. Comprising both excursion magnitude and duration, kinematic velocity may be a more complete metric to evaluate age-related swallowing performance.

Effect of neuromuscular electrical stimulation on hyolaryngeal structural movement in post-stroke dysphagia

Objective To explore the effect of neuromuscular electrical stimulation(NMES) on hyolaryngeal structural movement in post-stroke dysphagia. Methods Thirty patients with post-stroke dysphagia were randomly divided into 3 groups (n=10) namely group A, group B and group C. On the basis of routine swallowing training, medication and rehabiliation given to group C, group A was provided with VitalStim therapy on both suprahyoid and infrahyoid muscles, while group B was only on suprahyoid muscles lasting 2 weeks. Before and after treatment, the Video Fluoroscopy Swallowing Study (VFSS) was carried out and the upward and forward displacement distances of the hyoid and thyroid cartilage when swallowing pap were measured. Moreover, water swallow test, dysphagia severity scale and DOSS scores were used to assess the swallowing function. Results After 2 weeks' treatment, the water drinking test score, dysphagia severity scale and DOSS scores increased significantly in all groups than before treatment. The water drinking test score of group A (2.40±1.26) and group B (2.10±0.99), dysphagia severity scale of group A (5.30±1.89) and group B(5.20±1.69), as well as the DOSS level of group A (5.20±1.40) and group B (5.10±1.45) were significantly better than the control group. However, no significant difference was observed in all measurements between group A and group B. The group B revealed a significantly increase in anterior hyoid excursion distance of (12.15±7.59) mm, much bigger than that before treatment and that of group A and B after treatment. Conclusion NMES on the basis of traditional swallowing training can improve the swallowing function of post-stroke dysphagia patients, and NMES on suprahyoid muscles can further induce an increase in anterior hyoid excursion. Key words: Stroke; Neuromuscular electrical stimulation; Dysphagia; Video fluoroscopic swallowing study; Hyolaryngeal structural movement

Effortful swallow enhances vertical hyolaryngeal movement and prolongs duration after maximal excursion.

Effortful swallowing (EFS) is a common compensatory swallowing manoeuver for dysphagia patients. We investigated the influence of EFS on temporal and spatial characteristics of the movements of the hyoid bone, larynx and epiglottis in healthy subjects. A total of 41 volunteers swallowed 10 mL of diluted barium solution using two swallowing strategies: usual and effortful swallowing (USS and EFS). The motions of the hyoid bone, larynx and epiglottis were tracked using frame-by-frame kinematic motion analysis of videofluoroscopic images. Maximal velocities and maximal displacements of hyoid and larynx, the maximal angle of the epiglottic tilt, and the durations of hyoid excursion, laryngeal elevation and epiglottic tilt were measured. Compared to USS, EFS was associated with significantly greater vertical displacement of the hyoid (P < 0.001), vertical and horizontal displacement of the larynx (P = 0.003, P = 0.019), and maximal angle of the epiglottic tilt (P = 0.001). In addition, the durations of the vertical and horizontal excursions of the hyoid, vertical excursion of the larynx and the epiglottic tilt were greater in EFS, compared with USS. Effortful swallowing was also associated with significantly greater maximum velocities of the hyoid and larynx during swallowing. In conclusion, the EFS manoeuver facilitates vertical speed and distance of hyolaryngeal excursion and epiglottic tilt and extends the duration of excursion and the epiglottic tilt, especially after reaching maximal excursion in healthy subjects. These results confirm the temporal and kinematic benefits of airway protection induced by the EFS manoeuver.

Temporal characteristics of hyolaryngeal structural movements in normal swallowing.

To evaluate the relationship between movements of hyolaryngeal structures and fluid bolus transition in normal swallowing using automatized kinematic analysis of the videofluoroscopic swallowing study (VFSS). A prospective, descriptive study. Seventy-five healthy volunteers underwent VFSS with 2 mL of diluted barium. The timing and sequence of structural movements were measured for laryngeal elevation (LE), hyoid excursion (HE), epiglottic rotation (ER), and fluid bolus transition. The rapid movement of LE (reference time point) was initiated simultaneously with the fluid bolus head passing the mandibular angle (-0.05 s, P = .07), followed by rapid onset of HE with significant temporal difference (P < .001). After the hyoid onset, onset of ER (0.17 s, P < .001), entrance of the bolus through upper esophageal sphincter (0.33 s, P < .001), maximal point of LE (0.52 s, P < .001), HE (0.53 s, P = .344), and maximal point of ER (0.64 s, P < .001) followed sequentially. For subgroup analysis, we classified 50 subjects without premature bolus loss (PBL) or pharyngeal triggering delay (PTD) into the "early group," and 24 subjects with PBL or PTD for <1 s into the "late group." In both groups, the sequence of the structural movements did not change. The early group showed significant correlation between the fluid transition and structural movements; both LE and HE were initiated when the bolus passed the mandibular angle, and the ER was initiated when the bolus reached the vallecula. We demonstrated a characteristic pattern of hyolaryngeal structural movements in normal swallowing. The results may serve as a basis for classifying and analyzing aspiration patterns in patients with dysphagia. NA.

Use of an Anatomical Scalar to Control for Sex-Based Size Differences in Measures of Hyoid Excursion During Swallowing

Traditional methods for measuring hyoid excursion from dynamic videofluoroscopy recordings involve calculating changes in position in absolute units (mm). This method shows a high degree of variability across studies but agreement that greater hyoid excursion occurs in men than in women. Given that men are typically taller than women, the authors hypothesized that controlling for participant size might neutralize apparent sex-based differences in hyoid excursion. Hyoid excursion in 20 young (<45) healthy volunteers (10 male), stratified by height, was measured in a tightly controlled videofluoroscopic protocol. The study identified an anatomical scalar (C2-C4 length), visible on the videofluoroscopic image, correlated with participant height. This scalar differed significantly between men and women. By incorporating the anatomical scalar as a continuous covariate in repeated measures mixed-model analyses of variance of hyoid excursion, apparent sex-based differences were neutralized. Transforming measures of hyoid excursion into anatomically scaled units achieved the same result, reducing variation attributable to sex-based differences in participant size. Hyoid excursion during swallowing is dependent on a person's size. If measurements do not control for this source of variation, apparent sex differences in hyoid excursion are seen.

Coordinate mapping of hyolaryngeal mechanics in swallowing.

Characterizing hyolaryngeal movement is important to dysphagia research. Prior methods require multiple measurements to obtain one kinematic measurement whereas coordinate mapping of hyolaryngeal mechanics using Modified Barium Swallow (MBS) uses one set of coordinates to calculate multiple variables of interest. For demonstration purposes, ten kinematic measurements were generated from one set of coordinates to determine differences in swallowing two different bolus types. Calculations of hyoid excursion against the vertebrae and mandible are correlated to determine the importance of axes of reference. To demonstrate coordinate mapping methodology, 40 MBS studies were randomly selected from a dataset of healthy normal subjects with no known swallowing impairment. A 5 ml thin-liquid bolus and a 5 ml pudding swallows were measured from each subject. Nine coordinates, mapping the cranial base, mandible, vertebrae and elements of the hyolaryngeal complex, were recorded at the frames of minimum and maximum hyolaryngeal excursion. Coordinates were mathematically converted into ten variables of hyolaryngeal mechanics. Inter-rater reliability was evaluated by Intraclass correlation coefficients (ICC). Two-tailed t-tests were used to evaluate differences in kinematics by bolus viscosity. Hyoid excursion measurements against different axes of reference were correlated. Inter-rater reliability among six raters for the 18 coordinates ranged from ICC = 0.90 - 0.97. A slate of ten kinematic measurements was compared by subject between the six raters. One outlier was rejected, and the mean of the remaining reliability scores was ICC = 0.91, 0.84 - 0.96, 95% CI. Two-tailed t-tests with Bonferroni corrections comparing ten kinematic variables (5 ml thin-liquid vs. 5 ml pudding swallows) showed statistically significant differences in hyoid excursion, superior laryngeal movement, and pharyngeal shortening (p < 0.005). Pearson correlations of hyoid excursion measurements from two different axes of reference were: r = 0.62, r2 = 0.38, (thin-liquid); r = 0.52, r2 = 0.27, (pudding). Obtaining landmark coordinates is a reliable method to generate multiple kinematic variables from video fluoroscopic images useful in dysphagia research.