Effect of the Effortful Swallow and the Mendelsohn Maneuver on Tongue Pressure Production against the Hard Palate

Although effortful swallow and the Mendelsohn maneuver are commonly used in dysphagia rehabilitation, little is known about their effects on tongue-palate pressure production. The purpose of this study was to investigate the effects of effortful swallow and the Mendelsohn maneuver on tongue pressure production. Fourteen healthy volunteers (10 men, 4 women; age range = 21–41 years) participated. Tongue pressures during dry swallow, water swallow, effortful swallow, and the Mendelsohn maneuver were measured using a sensor sheet system with five measurement points on the hard palate. Sequential order, duration, maximal magnitude, and the integrated value of tongue pressure at each measurement point were compared among the four tasks. Onset of tongue pressure at the posterior-circumferential parts occurred first in the Mendelsohn maneuver; that at the anterior-median part was earlier than at other parts in the effortful swallow. At all measurement points, tongue pressure duration was significantly longer in the Mendelsohn maneuver than in other tasks. Effortful swallow was most effective in increasing tongue pressure. The integrated value of tongue pressure at the posterior-circumferential parts in the Mendelsohn maneuver and at the median parts in the effortful swallow showed a tendency to increase. These results suggest that tongue pressure increases along a wide part of the hard palate in effortful swallow because the anchor of tongue movement is emphasized at the anterior part of the hard palate. The Mendelsohn maneuver provides prolonged and accentuated tongue-palate contact at the posterior-circumferential parts, which might be important for hyoid-laryngeal elevation during swallowing.     

The Effect of Voluntary Pharyngeal Swallowing Maneuvers on Esophageal Swallowing Physiology

The purpose of our study was to evaluate whether swallowing maneuvers designed to impact pharyngeal physiology would also impact esophageal physiology. Healthy volunteers underwent high-resolution manometry while performing three randomized swallowing maneuvers with and without a 5-ml bolus: normal swallowing, Mendelsohn maneuver, and effortful swallowing. We examined esophageal parameters of peristaltic swallows, hypotensive or failed swallows (“nonperistaltic swallows”), distal contractile integral (DCI), contractile front velocity (CFV), intrabolus pressure, and transition zone (TZ) defect. Four females and six males (median age 39 years; range 25–53) were included in the study. The overall number of nonperistaltic swallows was 21/40 (53 %) during normal swallowing, 27/40 (66 %) during the Mendelsohn maneuver, and 13/40 (33 %) during effortful swallowing. There were significantly more overall nonperistaltic swallows with the Mendelsohn maneuver compared with effortful swallowing (p = 0.003). While swallowing a 5-ml bolus, there were more nonperistaltic swallows during the Mendelsohn maneuver (12/20, 60 %) compared to that during normal swallowing (6/20, 30 %) (p = 0.05) and more peristaltic swallows during effortful swallowing as compared to Mendelsohn maneuver (p = 0.003). Intrabolus esophageal pressure was greater during the Mendelsohn maneuver swallows in the bolus-swallowing condition as compared to normal swallowing (p = 0.02). There was no statistical difference in DCI, CFV, or TZ defect between swallowing conditions. The Mendelsohn maneuver may result in decreased esophageal peristalsis while effortful swallowing may improve esophageal peristalsis. Because it is important to understand the implications for the entire swallowing mechanism when considering retraining techniques for our patients, further investigation is warranted.     

A new evaluation of the upper esophageal sphincter using the functional lumen imaging probe: a preliminary report

Objective and reliable evaluation of upper esophageal sphincter (UES) opening during swallowing based on videofluoroscopy and pharyngeal manometry challenges dysphagia clinicians. The functional lumen imaging probe (FLIP) is a portable tool based on impedance planimetry originally designed to measure esophogastric junction compliance. It is hypothesized that FLIP can evaluate UES distensibility, and can provide UES diameter and pressure measurements at rest, during swallowing, and during voluntary maneuvers. Eleven healthy adult subjects consented to FLIP evaluation. The probe was inserted transorally, and the balloon was positioned across the UES. Two 20‐mL ramp distensions were completed. Changes in UES diameter and intraballoon pressure were measured during dry and 5‐mL liquid swallows, and during voluntary swallow postures and maneuvers employed in clinical practice. The protocol was completed by 10 of 11 healthy subjects. Mean intraballoon pressure increased throughout 5‐mL (5.8 mmHg; ?4.5–18.6 mmHg), 10‐mL (8.7 mmHg; 2.3–28.5 mmHg), 15‐mL (17.3 mmHg; 9.5–34.8 mmHg), and 20‐mL (31.2 mmHg; 16–46.3 mmHg) balloon volumes. Mean resting UES diameter (4.9 mm) increased during dry swallows (9.2 mm) and 5‐mL liquid swallows (7.7 mm). Mean UES diameter increased during 5‐mL liquid swallows with head turn to right (8.1 mm) and left (8.3 mm), chin tuck (8.4 mm), effortful swallow (8.5 mm), Mendelsohn maneuver (8.1 mm), and supraglottic swallow (7.8 mm). FLIP was safely inserted and distended in the UES, and provided useful quantitative data regarding UES distensibility and UES diameter changes during swallowing maneuvers. Further research is being conducted to explore the role of FLIP in UES evaluation.     

Effects of the Mendelsohn Maneuver on Extent of Hyoid Movement and UES Opening Post-Stroke

The Mendelsohn maneuver, voluntary prolongation of laryngeal elevation during the swallow, has been widely used as a compensatory strategy to improve upper esophageal sphincter (UES) opening and bolus flow. Recent research suggests that when used as a rehabilitative exercise, it significantly improves duration of hyoid movement and positively impacts duration of UES opening (DOUESO). The data presented here were derived from that same prospective crossover study of 18 participants with dysphagia post-stroke evaluated with videofluoroscopy after treatment using the Mendelsohn maneuver versus no treatment. Results demonstrate gains in the extent of hyoid movement and UES opening and improvements in coordination of structural movements with each other as well as with bolus flow.     

Lateral Pharyngeal Wall Motion during Swallowing Using Real Time Ultrasound

B-mode ultrasound imaging has been used primarily to detect temporal and spatial movements of the tongue during the oral preparatory and oral stages of swallowing. The purpose of this study was to investigate the application of M-mode (motion mode) ultrasound imaging as a method to quantify the duration and displacement of single regions along the lateral pharyngeal wall during swallows of two bolus volumes and during three swallow maneuvers (supraglottic, super-supraglottic and Mendelsohn maneuver). In 5 normal subjects, simultaneous B/M-mode images were captured at two regions along the lateral pharyngeal wall. Computer-assisted video analysis of each swallow sequence provided spatial coordinates and durational measures. Results indicated no significant differences in displacements of the lateral pharyngeal wall across bolus volumes, swallow maneuvers, or recording sites. Significant differences (p < 0.001) in lateral pharyngeal wall duration occurred as a function of volitional swallow maneuvers. Greater durations (p < 0.05) were found for the Mendelsohn and super-supraglottic swallow maneuvers. The data demonstrate that B/M-mode ultrasound imaging provides a simple, noninvasive method to visually examine movements of the lateral pharyngeal wall and may provide a clinical method for assessing the effects of direct swallowing therapies at the level of the mid-oropharynx.     

The Effect of an Effortful Swallow on the Normal Adult Esophagus

The effect of an effortful swallow on the healthy adult esophagus was investigated using concurrent oral and esophageal manometry (water perfusion system) on ten normal adults (5 males and 5 females, 20-35 years old) while swallowing 5-ml boluses of water. The effects of gender, swallow condition (effortful versus noneffortful swallows), and sensor site within the oral cavity, esophageal body, and lower esophageal sphincter (LES) were examined relative to amplitude, duration, and velocity of esophageal body contractions, LES residual pressure, and LES relaxation duration. The results of this study provide novel evidence that an effortful oropharyngeal swallow has an effect on the esophageal phase of swallowing. Specifically, effortful swallowing resulted in significantly increased peristaltic amplitudes within the distal smooth muscle region of the esophagus, without affecting the more proximal regions containing striated muscle fibers. The findings pertaining to the LES are inconclusive and require further exploration using methods that permit more reliable measurements of LES function. The results of this study hold tremendous clinical potential for esophageal disorders that result in abnormally low peristaltic pressures in the distal esophageal body, such as achalasia, scleroderma, and ineffective esophageal motility. However, additional studies are necessary to both replicate and extend the present findings, preferably using a solid-state manometric system in conjunction with bolus flow testing on both normal and disordered populations, to fully characterize the effects of an effortful swallow on the esophagus.     

Surface Electromyographic and Electroglottographic Studies in Normal Subjects Under Two Swallow Conditions: Normal and During the Mendelsohn Manuever

Surface electromyography (EMG) has been used successfully in teaching patients swallow maneuvers in clinical settings. The present study aims to determine if surface EMG can reliably demonstrate differences in muscle activity between the normal swallow and the Mendelsohn maneuver and whether there is a close temporal relationship between submental muscles and laryngeal elevation as demonstrated by electroglottography (EGG). Surface EMG was measured from five muscle groups (superior and inferior orbicularis oris, masseter, submental and infrahyoid) in 20 normal subjects under two swallowing conditions: normal and during performance of the Mendelsohn maneuver. A significant difference in EMG activity from the submental muscle group between the normal swallow and the Mendelsohn maneuver indicates that EMG at this location can be used reliably to differentiate between these two swallow conditions. The onset of submental activity and laryngeal elevation occurred within 10 ms of each other. The offset of submental activity and the return of the larynx to its resting position occurred within 24 ms of each other. Regarding the temporal relationship among the five muscle groups, the sequence of the most frequent muscle initiation was orbicularis oris inferior, orbicularis oris superior, masseter, submental muscle group, and infrahyoid muscle group. The sequence of the most frequent muscle termination was orbicularis oris superior, orbicularis oris inferior, masseter, submental muscle group, and infrahyoid muscle group in both normal swallow and the Mendelsohn maneuver.     

Effects of Effortful Swallow on Cardiac Autonomic Regulation

Swallowing-induced changes in heart rate have been recently reported. However, it is not apparent the responses of heart rate variability (HRV) elicited by effortful swallow maneuver. We investigated the acute effects of effortful swallowing maneuver on HRV. This study was performed on 34 healthy women between 18 and 35 years old. We assessed heart rate variability in the time (SDNN, RMSSD, and pNN50) and frequency (HF, LF, and LF/HF ratio) domains and, visual analysis through the Poincaré plot. The subjects remained at rest for 5 min during spontaneous swallowing and then performed effortful swallowing for 5 min. HRV was analyzed during spontaneous and effortful swallowing. We found no significant differences for SDNN, pNN50, RMSSD, HF in absolute units (ms²). There is a trend for increase of LF in absolute (p = 0.05) and normalized (p = 0.08) units during effortful swallowing. HF in normalized units reduced (p = 0.02) during effortful swallowing and LF/HF ratio (p = 0.03) increased during effortful swallowing. In conclusion effortful swallow maneuver in healthy women increased sympathetic cardiac modulation, indicating a cardiac overload.     

Training Effects of the Effortful Swallow Under Three Exercise Conditions

The effortful swallow achieves overload through high effort. It was predicted that both immediate effects on biomechanics and long-term neuromuscular adaptations would be facilitated by maximal overload during this exercise. This study examined how high-effort sips from small-diameter straws influenced linguapalatal swallow pressures. Additionally, training effects of effortful swallows preceded by high-effort sips were compared to two other exercise conditions: effortful swallows preceded by maximum effort lingual elevation and effortful swallows performed in isolation. Training outcomes included linguapalatal pressures produced during effortful and noneffortful swallows, and maximum isometric pressure (MIP) produced during tongue elevation and interlabial compression. Forty healthy adults participated in the experiment. Lingual–palatal swallowing pressure during non effortful and effortful swallows and MIPs were measured prior to and after 4 weeks of training. Prior to training, anterior linguapalatal pressures were significantly higher during effortful compared to noneffortful swallows. Anterior linguapalatal pressures did not significantly differ during swallows preceded by sips from high-resistance straws. Weak correlations were observed between tongue MIP and linguapalatal pressures during effortful swallows. After training, anterior linguapalatal pressures significantly increased, with training effects more dramatic for effortful swallows. Anterior tongue MIP also significantly increased. Gains in anterior linguapalatal pressure were not correlated with gains in tongue MIP. Training effects did not vary across exercise condition. The study failed to find a training advantage of pairing the effortful swallow with a precursor movement. The results demonstrated specificity of training, with more dramatic benefits observed for effortful swallows relative to noneffortful swallows. Further investigation is needed to characterize training effects in older adults and patients with dysphagia.     

Supraglottic swallow,effortful swallow,and chin tuck did not alter hypopharyngeal intrabolus pressure in patients with pharyngeal dysfunction

Simultaneous videoradiography and solid-state manometry (videomanometry) were performed in 8 patients (4 women, 4 men; age range = 46–81 years, mean age = 70 years) with pharyngeal dysfunction in order to disclose any changes in intrabolus pressure during swallowing maneuvers. Five of the patients had severe pharyngeal dysfunction with frequent misdirected swallows. Three of the patients had moderate pharyngeal dysfunction with delayed initiation of pharyngeal swallow. Three different swallowing techniques were applied: supraglottic swallow, effortful swallow, and chin tuck. Pharyngeal intrabolus pressure was analyzed at the level of the inferior pharyngeal constrictor. Supraglottic swallow, effortful swallow, and chin tuck did not alter peak amplitude or duration of the intrabolus pressure.     

Timing of Pharyngeal and Upper Esophageal Sphincter Pressures as a Function of Normal and Effortful Swallowing in Young Healthy Adults

The effect of effortful swallow on pharyngeal pressure and UES relaxation onsets and durations was examined. Eighteen adults, nine males and nine females (mean age = 27.9 yr), participated. Timing of pharyngeal pressure and onset and duration of UES relaxation were measured across ten trials of normal and ten trials of effortful swallows. Results revealed that manometric timing measurements are consistent across trials. The first and second statistical analyses investigated the pharyngeal pressure and UES relaxation onsets and durations, respectively. Both analyses identified a significant interaction of swallow type (i.e., effortful vs. normal) by manometric sensor location (p < 0.05). Across normal and effortful swallows, UES relaxation preceded pharyngeal pressure onsets, yet the rate of change (or degree of delay) varied across the sensors. Furthermore, the effortful swallow elicited longer pharyngeal pressure and UES relaxation durations, yet the pressure duration measured in the upper pharynx was significantly longer than that measured lower in the pharynx. These findings offer insight as to the potential positive and negative influence of the effortful swallow on pharyngeal timing.     

Effect of Bolus Volume and Viscosity on Pharyngeal Automated Impedance Manometry Variables Derived for Broad Dysphagia Patients

Automated impedance manometry (AIM) analysis measures swallow variables defining bolus timing, pressure, contractile vigour, and bolus presence, which are combined to derive a swallow risk index (SRI) correlating with aspiration. In a heterogeneous cohort of dysphagia patients, we assessed the impact of bolus volume and viscosity on AIM variables. We studied 40 patients (average age = 46 years). Swallowing of boluses was recorded with manometry, impedance, and videofluoroscopy. AIMplot software was used to derive functional variables: peak pressure (PeakP), pressure at nadir impedance (PNadImp), time from nadir impedance to peak pressure (TNadImp-PeakP), the interval of impedance drop in the distal pharynx (flow interval, FI), upper oesophageal sphincter (UES) relaxation interval (UES RI), nadir UES pressure (Nad UESP), UES intrabolus pressure (UES IBP), and UES resistance. The SRI was derived using the formula SRI = (FI * PNadImp)/(PeakP * (TNadImp-PeakP + 1)) * 100. A total of 173 liquid, 44 semisolid, and 33 solid boluses were analysed. The SRI was elevated in relation to aspiration. PeakP increased with volume. SRI was not significantly altered by bolus volume. PNadImp, UES IBP, and UES resistance increased with viscosity. SRI was lower with increased viscosity. In patients with dysphagia, the SRI is elevated in relation to aspiration, reduced by bolus viscosity, and not affected by bolus volume. These data provide evidence that pharyngeal AIM analysis may have clinical utility for assessing deglutitive aspiration risk to liquid boluses.     

Event Sequence Variability in Healthy Swallowing: Building on Previous Findings

This study builds on previous work by Kendall, Leonard, and McKenzie, which investigated event sequence variability for 12 paired events during swallowing by healthy volunteers. They identified four event pairs that always occurred in a stereotyped order and a most common occurring overall order of events during swallowing. In the current study, we investigated overall event sequencing and the same four paired events in a sample of swallows by healthy young (under 45 years old) volunteers. Data were collected during a 16-swallow lateral videofluoroscopy protocol, which included manipulations of bolus volume, barium density, bolus viscosity, and swallow cueing. Our results agreed with previous findings that variable event sequencing is found in healthy swallowing, and, in regard to obligatory sequencing of two paired events, movement of the arytenoids toward the base of the epiglottis begins prior to upper esophageal sphincter (UES) opening and maximum hyolaryngeal approximation occurs after UES opening. However, our data failed to replicate the previous findings that there is obligatory sequencing of maximum pharyngeal constriction after maximal UES distension and the UES opens before bolus arrival at the UES. The most common observed overall event sequence reported by Kendall et al. was observed in only 4/293 swallows in our dataset. Manipulations of bolus volume, bolus viscosity, barium concentration, swallow cueing, and swallow repetitions could not completely account for the differences observed between the two studies.     

Use of the electroglottograph for measurement of temporal aspects of the swallow: Preliminary observations

The electroglottograph (EGG) is a noninvasive, electrical impedance device that was developed for observing vocal fold contact during phonation. After a thorough study of the frequency response characteristics of the EGG, we found that the EGG output can be used to identify maximum laryngeal displacement and the duration of laryngeal movement during swallowing. With a small intranasal pressure transducer placed beneath the velum and the EGG electrodes placed externally on the thyroid cartilage, additional information on the temporal aspects of the swallow can be measured. The EGG has direct clinical application when teaching such techniques as the safe swallow and Mendelsohn maneuver and it is useful as a research technique when using repeated measures designed to study the swallow reflex.     

Upper esophageal sphincter function during deglutition

Upper esophageal sphincter function was investigated during swallows of graded volumes in 8 normal volunteers. Concurrent recordings of video-fluoroscopic and manometric studies were obtained and correlated with each other by means of a videotimer. Maximal upper esophageal sphincter (UES) pressure was typically located 1.5 cm distal to the air-tissue interface between the hypopharynx and the proximal margin of the sphincter. The region in which UES pressure was greater than or equal to 50% maximal averaged 1.0 cm in length. Thus, the physiologic high-pressure zone of the UES corresponds in size and location to that of the cricopharyngeus muscle. Fluoroscopic analysis of sphincter movement indicated that the sphincter high-pressure zone moved 2.0-2.5 cm orally during swallowing and that the magnitude of the orad movement was directly related to the volume of barium swallowed. The maximal anterior-posterior diameter of sphincter opening during a swallow ranged from 0.9 to 1.5 cm and was also directly related to the volume swallowed. The intervals of UES opening and relaxation increased significantly with increasing bolus volume; the duration of UES relaxation ranged from a mean of 0.37 s for dry swallows to 0.65 s for 20-ml swallows. Thus, the dynamics of UES function during deglutition are dependent upon the volume of the swallowed bolus. Larger bolus volumes are accommodated by both an increased diameter of sphincter opening and by prolongation of the interval of sphincter relaxation. Analysis of the timing of other reference points within the pharyngeal swallow sequence indicated that as the manometric interval of UES relaxation increased, the period of laryngeal elevation was prolonged, the UES relaxed earlier and contracted later, and the interval between the onset of laryngeal elevation and hypopharyngeal contraction increased.     

Videomanometric Analysis of Supraglottic Swallow, Effortful Swallow, and Chin Tuck in Healthy Volunteers

Simultaneous videoradiography and solid-state manometry (videomanometry) was applied in eight healthy volunteers (four women, four men; age range 25–64 years, mean age 41 years) without swallowing problems. Three different swallowing techniques were tested; supraglottic swallow, effortful swallow, and chin tuck. Seven videoradiographic variables and six manometric variables were analyzed. The supraglottic swallowing technique did not differ significantly from that of the control swallows. The effortful swallow had a significantly (p= 0.0001) reduced hyoid–mandibular distance preswallow due to an elevation of the hyoid and the larynx, which caused a significantly (p= 0.007) reduced maximal hyoid movement and a significantly (p= 0.009) reduced laryngeal elevation during swallow. The chin tuck swallow had a significantly (p= 0.001) reduced laryngohyoid distance and also a significantly (p= 0.004) reduced hyoid–mandibular distance. The chin tuck swallow also displayed significantly (p= 0.003) weaker pharyngeal contractions. Videomanometry allows for analysis of bolus transport, movement of anatomical structures, and measurement of intraluminal pressures. These variables are important when evaluating swallowing techniques. In the present study, we made a few observations that never have been reported before. When healthy volunteers performed supraglottic swallow, they performed the technique somewhat differently. Therefore, we assume dysphagic patients would need a substantial period of training to perform a technique efficiently. Chin tuck could impair protection of the airways in dysphagic patients with weak pharyngeal constrictor muscles.     

The Influence of Orolingual Pressure on the Timing of Pharyngeal Pressure Events

This study explored the influence of two methods of effortful swallow execution on the timing of pharyngeal pressure events. Participants were asked to either emphasize or minimize tongue-to-palate contact during performance of the maneuver. Twenty healthy participants were evaluated using concurrent submental surface electromyography (sEMG), orolingual manometry, and pharyngeal manometry. Each subject performed three repetitions of three counterbalanced tasks (noneffortful dry swallows, effortful dry swallows with tongue-to-palate emphasis, and effortful dry swallows with tongue-to-palate de-emphasis). Four variables were measured: Onset Lag vs. sEMG Peak, Peak Lag vs. sEMG Peak, Total Duration, and Percent Rise Time to Peak. Compared to noneffortful swallows, the effortful swallow task elicited significantly earlier onsets and peaks of pharyngeal pressures relative to the submental sEMG peak. Total pressure event durations were greater and rise times were significantly shorter. When comparing the two methods of effortful swallow execution, a longer latency to peak proximal pharyngeal pressure was found in the tongue-to-palate emphasis condition. These results support the interpretation that the effortful swallow maneuver involves generation of higher velocity bolus driving forces that propel the bolus into and through the pharynx with greater efficiency and that pressure is then sustained to facilitate more complete bolus clearance. Work performed at the Van der Veer Institute for Parkinson’s and Brain Research, Christchurch, New Zealand     

Kinematic and Temporal Factors Associated with Penetration–Aspiration in Swallowing Liquids

In this study we undertook careful analysis of 13 quantitative physiological variables related to oropharyngeal swallowing from a sample of 42 subacute patients referred for dysphagia assessment. Each patient underwent a videofluoroscopic swallowing examination in which they swallowed up to five boluses of 22 % w/v ultrathin liquid barium suspension administered by teaspoon. Our goal was to determine whether scores on 13 kinematic or temporal parameters of interest were independently associated with the presence of penetration–aspiration in the final compiled dataset of 178 swallows. Participants were classified as aspirators based on the presence of at least one swallow that demonstrated a Penetration–Aspiration Scale score of ≥3. The parameters of interest included six kinematic parameters for capturing hyoid position, three swallow durations [laryngeal closure duration, hyoid movement duration, and upper esophageal sphincter (UES) opening duration], and four swallow intervals (laryngeal closure to UES opening, bolus dwell time in the pharynx prior to laryngeal closure, stage transition duration, and pharyngeal transit time). Mixed-model repeated-measures ANOVAs were conducted to determine the association between each parameter and aspiration status. Only 1 of the 13 parameters tested distinguished aspirators from nonaspirators: aspirators demonstrated significantly shorter UES opening duration. In addition, a trend toward reduced maximum superior position of the hyoid was seen in aspirators. Limitations and future considerations are discussed.     

Videomanometric Analysis of Supraglottic Swallow, Effortful Swallow, and Chin Tuck in Patients with Pharyngeal Dysfunction

Simultaneous videoradiography and solid-state manometry (videomanometry) was performed in 8 patients (4 women, 4 men; age range = 46-81 years, mean age = 70 years) with pharyngeal dysfunction. Five patients had severe pharyngeal dysfunction with frequent misdirected swallows. Three patients had moderate pharyngeal dysfunction with delayed initiation of pharyngeal swallow. Three different swallowing techniques were used: supraglottic swallow, effortful swallow, and chin tuck. Ten video radiographic variables and six manometric variables were analyzed. Contrast media penetration to the airways was analyzed regarding number of events and level of penetration. Supraglottic swallow, effortful swallow, and chin tuck did not reduce the number of misdirected swallows, but effortful swallow and chin tuck significantly (p = 0.008) reduced the depth of contrast penetration into the larynx and trachea. There was no significant improvement of pharyngeal retention. Chin tuck reduced the distance between the thyroid and the hyoid and the distance between the mandible and the hyoid. No other measured variable was significantly altered. This study shows that none of the different swallowing techniques reduced the number of misdirected swallows. However, there was a significantly reduced depth of the misdirected swallows. The swallowing techniques did not seem to prevent the occurrence of retention or improve weak pharyngeal constrictor muscles in this group of patients with severe to moderate dysfunction.