Prediction of Pharyngeal 3D Volume Using 2D Lateral Area Measurements During Swallowing.

This study evaluated the validity of pharyngeal 2D area measurements acquired from the lateral view for predicting the actual 3D volume in healthy adults during swallowing. Seventy-five healthy adults (39 females, 36 males; mean age 51.3 years) were examined using 320-row area detector computed tomography (320-ADCT). All participants swallowed a 10 mL honey-thick barium bolus upon command while seated in a 45° semi-reclining position. Multi-planar reconstruction images and dynamic 3D-CT images were obtained using Aquilion ONE software. Pharyngeal 2D area and 3D volume measurements were taken before swallowing and at the frame depicting maximum pharyngeal constriction. Pharyngeal volume before swallowing (PVhold) was accurately predicted by 2D area (R2 = 0.816). Adding height and sex to the model increased R2 to 0.836. Regarding pharyngeal volume during maximum constriction (PVmax), 2D area also exhibited acceptable predictive power (R2 = 0.777). However, analysis of statistical residuals and outliers revealed a greater tendency for prediction errors when there is less complete constriction of the pharynx as well as asymmetry in bolus flow or movement. Findings highlight the importance of routinely incorporating anterior-posterior views during VFSS exams. Future work is needed to determine clinical utility of pharyngeal volume measurements derived from 320-ADCT.

Location of the upper oesophageal sphincter during swallowing: Analysis using swallowing CT.

BACKGROUND: Upper oesophageal sphincter (UES) serves as an important anatomical and functional landmark during swallowing. However, the precise UES location before and during swallowing has not been well established. OBJECTIVE: This study aimed to determine upper oesophageal sphincter (UES) location and displacement during swallowing accounting for sex, age, and height in healthy adults using 320-row area detector computed tomography (320-ADCT). METHODS: Ninety-four healthy adults (43 males; 22-90 years) underwent 320-ADCT scanning while swallowing one trial of 10 mL honey thick barium. UES location at bolus hold and at maximum displacement and vertical displacement during swallowing were identified using the coordinates and the section classification of vertebrae (VERT scale). The differences and correlations of UES location and distance in terms of sex, age, and height were analysed using Mann-Whitney U test and Spearman's correlation coefficient. RESULTS: UES locations at bolus hold and at maximum displacement were significantly lower and UES vertical displacement was significantly larger in males than in females (p < .001). UES location at bolus hold became lower with increasing age (r = -.312, p = .002), but the negative correlation was low at maximum displacement (r = -.230, p = .026), resulting in larger vertical distance with ageing. UES locations showed high negative correlation at bolus hold with height (r = -.715, p < .001), and showed moderate negative correlation at maximum displacement with height (r = -.555, p < .001), although this effect was unclear when analysed by sex. CONCLUSION: Males showed lower UES location and larger displacement than females. The impact of age was evident with lower location before swallowing and larger displacement during swallowing. Differences observed by sex were not completely explained by using the VERT scale to adjust for height.

Timing of True Vocal Cords Closure for Safe Swallowing: A Review of 5 Studies Using 3D Analysis Using Computerized Tomography (CT).

Timely and complete laryngeal closure is critical for a successful swallow. Researchers have studied laryngeal closure, including true vocal cords (TVC) closure, closure of the arytenoids to the epiglottis base (laryngeal vestibule closure), and epiglottic inversion, but the most commonly available imaging tools have limitations that do not allow the study of these components individually. Swallowing computerized tomography (CT) has enabled three-dimensional dynamic visualization and quantitative evaluation of swallowing events providing a unique view of swallowing-related structures and their motion. Using CT, TVC closure can be visualized and evaluated on any plane or cross-section without being obscured by of laryngeal vestibule closure or epiglottis inversion. The current review summarizes the results of five papers evaluating the effects of bolus consistency and volume, posture, and age on TVC closure. The combined results of these studies suggest that TVC closure is responsive to oral sensory input based on bolus consistency and size and can be modulated in response to conditions perceived to increase the risk of airway invasion. These results are meaningful for dysphagia rehabilitation as it suggests that interventions to improve TVC closure are likely to enhance airway protection.

Effect of the Effortful Swallow on Pharyngeal Cavity Volume: Kinematic Analysis in Three Dimensions Using 320-Row Area Detector Computed Tomography.

This study evaluated the effects of the effortful swallow (ES) on pharyngeal cavity volume using three-dimensional kinematic analyses. Nine healthy volunteers (30.7 ± 7.8 years old) underwent a CT scan while swallowing 10 ml of honey thick liquid using no maneuvers (control) and during an ES. Upper and lower volumes (bordered by valleculae) of the pharyngeal air column and the bolus were measured at every frame and were compared between ES and control swallows. Duration of pharyngeal obliteration and the timing of swallowing events were also measured. Maximum volume and volume at the onset of hyoid anterosuperior movement using ES were significantly smaller than those in control swallows (p = 0.012, p = 0.015) in the upper pharynx but not significantly different in lower pharynx. Minimum pharyngeal volume was sustained for a longer time when ES was used compared to control swallows in both upper and lower pharynx (upper p = 0.016, lower p = 0.027). Onset of velopharyngeal closure was earlier when comparing ES and control swallows (p = 0.04). Termination of all events was significantly delayed when the ES was used (p < 0.05). Changes in the upper pharyngeal volume and in the onset of velopharyngeal closure suggest earlier pharyngeal constriction when using the ES. Longer pharyngeal obliteration and prolonged termination of velopharyngeal closure and epiglottis inversion suggest the prolonged pharyngeal constriction during the ES. These findings suggest the ES can be useful for improving the efficiency of swallowing.

3D-CT Evaluation of Swallowing: Metrics of the Swallowing Response Using Swallowing CT.

Videofluoroscopy and videoendoscopy dramatically changed the evaluation and management of swallowing disorders. Later advancements in techniques for the instrumental evaluation of swallowing were limited by technique and positioning. The advent of 320-row area detector CT solved previous challenges and allowed for the study of swallowing physiology and dysphagia in greater detail. In this summary, we describe the history and evolution of CT technology and describe research and clinical applications for the evaluation of swallowing physiology and pathophysiology.

Thin Liquid Bolus Volume Alters Pharyngeal Swallowing: Kinematic Analysis Using 3D Dynamic CT.

The previous studies reported that different volumes of thick liquid had an impact on spatiotemporal characteristics and pharyngeal response of swallowing. However, the bolus flow and swallowing motion pattern were different between thick and thin liquids. The effects of thin bolus volume on pharyngeal swallowing, especially true vocal cord (TVC) closure is still unclear. This study assessed the temporal characteristics when swallowing different volumes of thin liquid to determine the mechanical adaptation using 320-row area detector computed tomography (320-ADCT) and investigated a change of swallowing physiology including laryngeal closure, particularly TVC closure. Fourteen healthy women (28-45 years) underwent 320-ADCT while swallowing of 3, 10, and 20 ml of thin liquid barium in 45° semi-reclining position. Kinematic analysis was performed for each swallow including temporal characteristic, structural movements while swallowing, and maximal cross-sectional area of the upper esophageal sphincter (UES) opening. Bolus head reached to pharynx and esophagus earlier in larger volume significantly, indicating faster bolus transport as volume increased. There were significant effects on swallowing mechanism revealing earlier TVC closure and UES opening with increasing volume. Maximum cross-sectional area of the UES opening was increased to accommodate a larger bolus. Differences in mechanical adaptation through bolus transit and motion of swallowing structures were detected across increasing volumes. These volume-dependent adaptations potentially reduce the risk of aspiration. Understanding the swallowing physiological changes as volume increased is helpful for diagnosis and treatment of dysphagia patients as well as outcomes of swallowing rehabilitation in clinical practice.

An International Commentary on Dysphagia and Dysphonia During the COVID-19 Pandemic.

COVID-19 has had an impact globally with millions infected, high mortality, significant economic ramifications, travel restrictions, national lockdowns, overloaded healthcare systems, effects on healthcare workers' health and well-being, and large amounts of funding diverted into rapid vaccine development and implementation. Patients with COVID-19, especially those who become severely ill, have frequently developed dysphagia and dysphonia. Health professionals working in the field have needed to learn about this new disease while managing these patients with enhanced personal protective equipment. Emerging research suggests differences in the clinical symptoms and journey to recovery for patients with COVID-19 in comparison to other intensive care populations. New insights from outpatient clinics also suggest distinct presentations of dysphagia and dysphonia in people after COVID-19 who were not hospitalized or severely ill. This international expert panel provides commentary on the impact of the pandemic on speech pathologists and our current understanding of dysphagia and dysphonia in patients with COVID-19, from acute illness to long-term recovery. This narrative review provides a unique, comprehensive critical appraisal of published peer-reviewed primary data as well as emerging previously unpublished, original primary data from across the globe, including clinical symptoms, trajectory, and prognosis. We conclude with our international expert opinion on what we have learnt and where we need to go next as this pandemic continues across the globe.

Effects of head flexion posture in patients with dysphagia.

BACKGROUND: The chin-down posture is often used as a compensatory manoeuvre for patients with dysphagia. This posture presumably involves flexion of the head and/or neck, but this is not clearly defined. OBJECTIVE: This study aimed to assess the effects of head flexion posture in a retrospective study of videofluoroscopic examination of swallowing (VF). METHODS: A total of 73 patients who underwent VF both with and without head flexion posture in the lateral projection were included in the analysis. The head and neck angles at the initiation of the swallowing reflex, penetration-aspiration scale (PAS), nasopharyngeal closure time, stage transition duration, duration of laryngeal closure, time from swallowing reflex to laryngeal closure and to the opening of upper oesophageal sphincter (UES), duration of UES opening, location of the bolus leading edge at swallowing reflex, and bolus transition time were evaluated. RESULTS: The head flexion angle increased (p < 0.001), but the neck flexion angle did not change in the head flexion posture. Moreover, PAS improved (p < 0.001), aspiration was reduced (p < 0.001), the time between the swallowing reflex and the onset of laryngeal closure was shortened (p = 0.006), and the leading edge of the bolus at swallowing reflex became shallower (p = 0.004) in the head flexion posture. Other parameters did not significantly change. CONCLUSION: The head flexion posture resulted in earlier laryngeal closure and a shallower position of the leading bolus edge at swallowing reflex, resulting in PAS improvement and decreased aspiration.

A Consensus Statement for the Management and Rehabilitation of Communication and Swallowing Function in the ICU: A Global Response to COVID-19.

OBJECTIVE: To identify core practices for workforce management of communication and swallowing functions in coronavirus disease 2019 (COVID-19) positive patients within the intensive care unit (ICU). DESIGN: A modified Delphi methodology was used, with 3 electronic voting rounds. AGREE II and an adapted COVID-19 survey framework from physiotherapy were used to develop survey statements. Sixty-six statements pertaining to workforce planning and management of communication and swallowing function in the ICU were included. SETTING: Electronic modified Delphi process. PARTICIPANTS: Speech-language pathologists (SLPs) (N=35) from 6 continents representing 12 countries. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The main outcome was consensus agreement, defined a priori as ≥70% of participants with a mean Likert score ≥7.0 (11-point scale: 0=strongly disagree, 10=strongly agree). Prioritization rank order of statements in a fourth round was also conducted. RESULTS: SLPs with a median of 15 years of ICU experience, working primarily in clinical (54%), academic (29%), or managerial positions (17%), completed all voting rounds. After the third round, 64 statements (97%) met criteria. Rank ordering identified issues of high importance. CONCLUSIONS: A set of global consensus statements to facilitate planning and delivery of rehabilitative care for patients admitted to the ICU during the COVID-19 pandemic were agreed by an international expert SLP group. Statements focused on considerations for workforce preparation, resourcing and training, and the management of communication and swallowing functions. These statements support and provide direction for all members of the rehabilitation team to use for patients admitted to the ICU during a global pandemic.

Annular Flow in the Upper Esophageal Sphincter Demonstrated with Dynamic 320-row Area Detector Computed Tomography.

Understanding bolus flow patterns in swallowing (rheology, the study of flow) is fundamental to assessment and treatment of dysphagia. These patterns are complex and poorly understood. A liquid swallow is typically biphasic, including air, so the actual bolus has both liquid and gas phases. We report a novel observation of annular two-phase flow (a ring of liquid around a core of air) as thin liquids passed through the upper esophageal sphincter (UES). Dynamic CT was performed on 27 healthy asymptomatic volunteers swallowing liquid barium in a semi-reclining position. Each subject swallowed 3, 10, and 20 ml of either thin (14 subjects) or thick liquid (13 subjects). Sagittal and axial images were analyzed. Flow patterns in the UES were assessed on cross-sectional images. Annular flow was seen in the majority of subjects with thin liquid but few with thick liquid swallows. The percentage of Annular flow during UES opening was 3 ml 58%, 10 ml 58%, 20 ml 56% in thin and 3 ml 0%, 10 ml 4%, 20 ml 1% in thick. Annular flow was usually observed from the second or third frames after onset of UES opening. The other pattern, Plug flow was seldom seen with thin but was typical with thick liquid swallows. Annular flow was the most common pattern for thin liquids (but not thick liquids) passing through the UES. Annular flow has been defined as a liquid continuum adjacent to the channel wall with a gas continuum (core) in the center of the channel. The two regions are demarcated by a gas-liquid interface. Annular flow is typical for two-phase gas-liquid flow in a vertical or inclined channel. It results from the interaction of viscosity with cohesive and adhesive forces in the two phases. We infer that the difference in flow pattern between thin liquid-air and thick liquid-air boluses resulted from the differing magnitudes of viscous forces.

Effect of Tongue-Hold Swallow on Pharyngeal Contractile Properties in Healthy Individuals.

Tongue-hold swallow (THS) is a swallow exercise in which an individual swallows saliva while holding the anterior portion of the tongue between the front teeth. The effect of THS on pharyngeal contractile vigor is still unclear. The purpose of this study was to quantify THS using high-resolution manometry with a contractile integral analysis. Twenty-two healthy participants performed three different saliva swallow tasks: normal swallow, weak THS (in which the tongue was protruded 1 cm outside the upper incisors), and strong THS (in which the tongue was protruded 2 cm outside the upper incisors). The participants repeated each task twice randomly. Pharyngeal and upper esophageal sphincter metrics, including the pharyngeal contractile integral, were analyzed. Both weak and strong THS enhanced the velopharyngeal contractile integral and peak pressure compared with normal swallow (P < 0.01). THS also prolonged mesopharyngeal contraction (P < 0.01). Holding the tongue anteriorly during swallow requires significant biomechanical changes to pharyngeal contractile properties at the superior and middle pharyngeal constrictor levels; thus, it may serve as a resistance exercise for the muscles that are involved in bolus propulsion.

Effect of tongue-hold swallow on posterior pharyngeal wall using dynamic area detector computed tomography.

PURPOSE: The purpose of this study was to elucidate the effects of the tongue-hold swallow (THS) on the pharyngeal wall by quantifying posterior pharyngeal wall (PPW) anterior bulge during the THS. In addition, the effect of tongue protrusion length on the extent of pharyngeal wall anterior bulge was analysed. METHODS: Thirteen healthy subjects (6 males and 7 females, 23-43 years) underwent 320-row area detector CT during saliva swallow (SS) and THS at two tongue protrusion lengths (THS1 protrude the tongue as much as 1/3 of premeasured maximum tongue protrusion length (MTP-L) and THS2 protrude the tongue as much as 2/3 of MTP-L). To acquire images of the pharynx at rest, single-phase volume scanning was performed three times during usual breathing with no tongue protrusion (rest), protrusion of the tongue at 1/3 of MTP-L (rTHS1) and protrusion of the tongue at 2/3 of MTP-L (rTHS2). Length from cervical spine to PPW (PPW-AP) and the volume of pharyngeal cavity was measured and was compared between rest, rTHS1 and rTHS2 and between SS, THS1 and THS2. Correlation between MTP-L and PPW-AP was calculated in three conditions, SS, THS1 and THS2. RESULTS: PPW-AP at rest, rTHS1 and rTHS2 was 2.9 ± 0.6 mm, 3.0 ± 0.5 mm and 3.0 ± 0.5 mm, respectively, showing no significant differences across swallows. PPW-AP at the maximum pharyngeal constriction was 8.1 ± 2.0 mm, 9.1 ± 2.4 mm and 8.7 ± 2.0 mm in SS, THS1 and THS2, respectively. Compared to SS, PPW-AP in THS1 was significantly larger (p = 0.04) and PPW-AP in THS2 was not significantly different (p = 0.09). Pharyngeal volume at rest, rTHS1 and rTHS2 was 16.4 ± 5.2 mm3 , 18.4 ± 4.5 mm3 and 21.3 ± 6.2 mm3 , respectively. It was significantly larger during rTHS2 compared with rest or rTHS1 (rTHS2-rest p = 0.007, rTHS2-rTHS1 p = 0.007). Pharyngeal volume was completely obliterated (zero volume) at maximum pharyngeal contraction in all except one subject. There was no correlation between MTP-L and PPW-AP in any of the three conditions (SS, THS1 and THS2). DISCUSSION: This study demonstrated that the expanded pharyngeal cavity due to the tongue protrusion was completely obliterated by the increase in anterior motion of pharyngeal wall during THS. It also became clear that the degree of tongue protrusion did not linearly correlate with the movement of PPW during THS. There was no relationship between PPW motion and the MTP-L, suggesting that the effect of tongue protrusion is better determined in each subject by analysing the motion of PPW using imaging tools.

Outcomes of Dysphagia Following Stroke: Factors Influencing Oral Intake at 6 Months After Onset.

PURPOSE: This study aimed to describe recovery of dysphagia after stroke. We determined the proportion of stroke survivors with dysphagia on admission, discharge, and 6 months after stroke. Additionally, the factors affecting oral feeding 6 months after stroke were explored. METHODS: A total of 427 acute stroke patients were recruited prospectively. Presence of dysphagia was evaluated on admission, weekly until recovery was achieved, and at discharge. We compared stroke survivors with dysphagia who had complete recovery, who had dysphagia but achieved oral feeding, and who required tube feeding. Patient-reported eating ability was evaluated at 6 months. Patients who achieved oral feeding by 6 months were compared to those who had persistent tube feeding need. RESULTS: Fifty-five percent of stroke survivors had dysphagia on initial evaluation (3.1 ± 1.4 days after admission) and 37% at discharge (21.1 ± 12.4 days). At 6 months, 5% of patients required tube feeding. Among those who had dysphagia at initial evaluation, 32% had resolution of dysphagia within two weeks, 44% had dysphagia but started oral feeding before discharge, and 23% required alternative means of alimentation (nasogastric tube feeding, percutaneous endoscopic gastrostomy, parental nutrition) throughout hospitalization. At 6 months, 90% of stroke survivors who achieved oral feeding by discharge continued with oral feeding. Patients who achieved oral feeding after discharge had less cognitive impairments on admission and a higher speech therapist intervention rate after discharge. CONCLUSIONS: More than half of stroke survivors had dysphagia but the vast majority were able to return to oral feeding by 6 months. Cognitive function and dysphagia rehabilitation interventions were associated with return to oral feeding after hospital discharge.

Repetitive Peripheral Magnetic Stimulation for Strengthening of the Suprahyoid Muscles: A Randomized Controlled Trial.

OBJECTIVE: Head lift exercise is a widely known form of training in the rehabilitation of patients with dysphagia. This study aimed to compare muscular strength reinforcement training of the suprahyoid muscles using repetitive peripheral magnetic stimulation (rPMS) with head lift exercises in a randomized controlled trial. MATERIALS AND METHODS: Twenty-four healthy adults were randomly assigned to either the magnetic stimulation group (M group) or the head lift exercise group (H group). Both groups underwent training five days a week for two weeks. The primary outcome was the cervical flexor strength, and secondary outcomes were jaw-opening force, tongue pressure, muscle fatigue of the hyoid and laryngeal muscles, displacement of the hyoid bone and opening width of the upper esophageal sphincter (UES) while swallowing 10 mL of liquid, training performance rate, and pain. RESULTS: No dropouts were reported during the two-week intervention period. Cervical flexor strength significantly increased solely in the M group. Tongue pressure significantly improved in both groups. There were no significant differences in the jaw-opening force, median frequency rate of the anterior belly of the digastric muscle, sternohyoid muscle, sternocleidomastoid muscle, anterior and superior hyoid bone displacement, and UES opening width in both groups. CONCLUSIONS: Two-week rPMS of the suprahyoid muscles increased the strength of these muscles compared with the head lift exercise during the same period.

The effect of reclining position on swallowing function in stroke patients with dysphagia.

BACKGROUND: Dysphagia is a common problem in patients with a history of stroke. In Japan, a reclined position is commonly used as a compensatory technique to address this problem. OBJECTIVE: To evaluate the effect of reclined position on swallowing function in patients with stroke who had dysphagia. METHODS: A retrospective analysis was carried out on the videofluoroscopic examination of swallowing (VF) of 4ml honey-thick liquid swallows collected over 9 years. Penetration-aspiration scale (PAS) and residue scores were compared for the following: a body position at 90° upright (90°U) and 60° reclining (60°R) groups, as well as 60°R and 45° reclining (45°R) groups. RESULTS: Two hundred and five records from 98 subjects were reviewed. These included patients with ischaemic stroke (62%), haemorrhagic stroke (32%) and subarachnoid haemorrhage (6%). PAS scores were lower when the body was in a more reclined position (P < .001). The amount of residue in the valleculae and pyriform sinus also reduced in the more reclined position (P < .001). The deeper bolus head at swallowing onset was positively correlated with severe PAS (P < .001). CONCLUSIONS: These findings suggest that in patients with stroke who had dysphagia, a reclined position may be useful in reducing the risk of penetration and aspiration, and in decreasing the amount of residue in the pharyngeal area. The depth of the bolus head at the onset of swallowing increases the severity of penetration and aspiration.

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.

The effect of bolus consistency on pharyngeal volume during swallowing: Kinematic analysis in three dimensions using dynamic Area Detector CT.

OBJECTIVE: This study investigated the effects of bolus consistency on pharyngeal volume during swallowing using three-dimensional kinematic analysis. METHODS: Eight subjects (2 males and 6 females, mean ± SD 44 ± 10 years old) underwent a 320-row area detector scan during swallows of 10 mL of honey-thick liquid and thin liquid. Critical event timing (hyoid, soft palate, UES) and volume of pharyngeal cavity and bolus were measured and compared between two swallows. RESULTS: The pharynx is almost completely obliterated by pharyngeal constriction against the tongue base for both consistencies. There were no significant differences in maximum volume, minimum volume and pharyngeal volume constriction ratio values between thick and thin liquids. However, the pattern of pharyngeal volume change (decrease) was different. For thick liquids, the air volume started to decrease before the onset of hyoid anterosuperior movement and decreased rapidly after onset of hyoid anterosuperior movement. During thin liquid swallowing, air volume remained relatively large throughout the swallow and started to decrease later when compared to swallowing thick liquids. At onset of UES opening, the bolus volume was not significantly different between thin and thick liquids; however, air volume was significantly larger when swallowing thin liquids, which made the total volume of the pharyngeal cavity larger. CONCLUSION: This difference between the two consistencies is associated with differences in tongue motion to propel the bolus and clear the pharynx from possible residue.

The Association of 3-D Volume and 2-D Area of Post-swallow Pharyngeal Residue on CT Imaging.

Pharyngeal residue, the material that remains in the pharynx after swallowing, is an important marker of impairments in swallowing and prandial aspiration risk. The goals of this study were to determine whether the 2D area of post-swallow residue accurately represents its 3D volume, and if the laterality of residue would affect this association. Thirteen patients with dysphagia due to brainstem stroke completed dynamic 320-detector row computed tomography while swallowing a trial of 10 ml honey-thick barium. 3D volumes of pharyngeal residue were compared to 2D lateral and anterior-posterior areas, and a laterality index for residue location was computed. Although the anteroposterior area of residue was larger than the lateral area, the two measures were positively correlated with one another and with residue volume. On separate bivariate regression analyses, residue volume was accurately predicted by both lateral (R2 = 0.91) and anteroposterior (R2 = 0.88) residue areas, with limited incidence of high residuals. Half of the sample demonstrated a majority of pharyngeal residue lateralized to one side of the pharynx, with no effect of laterality on the association between areas and volume. In conclusion, the area of post-swallow pharyngeal residue was associated with volume, with limitations in specific cases. Direct measurement of pharyngeal residue volume and swallowing physiology with 3D-CT can be used to validate results from standard 2D instrumentation.

Hyoid Bone Movement at Rest by Peripheral Magnetic Stimulation of Suprahyoid Muscles in Normal Individuals.

OBJECTIVES: Neuromuscular electrical stimulation has been widely used in patients with dysphagia. However, obtaining sufficient hyoid bone movement through surface electrodes seems difficult. The aim of this study was to evaluate hyoid bone movement at rest through peripheral magnetic stimulation of the suprahyoid muscles in normal individuals. METHODS: Healthy adult men were recruited. A specially designed coil was connected to the peripheral magnetic stimulator. The coil was placed on the submental area of the subjects. Magnetic stimulation was performed at 30 Hz for 2 sec. The intensity level selected induces hyoid bone movement without causing intolerable pain to the subjects. The hyoid bone at rest between on- and off-magnetic stimulations of the suprahyoid muscles were identified using fluoroscopy at 30 frames/sec in lateral projection. Pain during peripheral magnetic stimulation was evaluated using the numerical rating scale (NRS). RESULTS: Eleven subjects aged 32 ± 9 years participated in this study. Magnetic stimulation resulted in 10.9 ± 2.8 mm forward displacement and 8.3 ± 4.1 mm (mean ± SD) upward displacement of the hyoid bone. The median NRS score during magnetic stimulation was 1. CONCLUSIONS: Peripheral magnetic stimulation is noninvasive and easy to perform. It does not require skin preparation, facilitates sufficient hyoid bone movement, and causes minimum level of pain.