An intraoral stent to improve examination of swallowing in a case involving gunshot wound to the face

A custom intraoral stent to facilitate oral bolus transport without external drooling and aspiration during radiographic examination of dysphagia in a patient with severely compromised swallowing mechanism due to self-inflicted gun-shot wound to the face is described. This hollow stent, which conforms to the contour of the intraoral space, allows passage of contrast medium during videofluoroscopic modified barium swallow tests resulting in consistent successful swallowing. Severe extraoral leakage (drooling), aspiration, and coughing occurred when the modified barium test was performed without this device.     

Relation of bolus size and pharyngeal swallow

To study the influence of bolus size on pharyngeal swallow, 20 dysphagic patients and 10 nondysphagic volunteers were examined cineradiographically while swallowing a bolus of 2.5, 5, 10, and 20 ml. Ten patients and 10 volunteers swallowed boluses in increasing volume while 10 patients swallowed boluses of decreasing volume. The movement of the hyoid bone occurred in a two-step fashion irrespective of the bolus size, and in all individuals. The speed of the apex of the bolus through the pharynx, measured by frame counting, increased with increasing size of the bolus. The speed of the peristaltic wave, as measured between vallecula and the PE segment, did not change with bolus size. Boluses of 10 or 20 ml caused penetration of barium into the larynx in 7 of the patients but in none of the volunteers. Our results suggest that pharyngeal constrictor activity, in terms of speed of peristalsis, is constant and not influenced by bolus volume.     

Correlation Varies with Different Time Lags Between the Motions of the Hyoid Bone,Epiglottis, and Larynx during Swallowing

Although coordination and timing of swallowing have often been investigated by using discrete timing events such as the onset, peak, and duration of specific motions, the sequence and duration of swallowing events cannot represent the coordination of the swallowing mechanism quantitatively. This study aimed to apply a cross-correlation analysis of the motions of the hyolaryngeal structures during swallowing as an objective method for measuring the coordination and timing of the motions. Forty healthy subjects swallowed 2 and 5 ml of diluted barium solution (35 %) and 5 ml of curd yogurt under videofluoroscopy. Hyolaryngeal motions in videofluoroscopic images were digitized using the motion analysis system. The time series of the horizontal and vertical hyoid motion, the laryngeal elevation, and the angle of the epiglottic tilt were analyzed using cross-correlation at each 1/60-s time lag. The results showed high and consistent cross-correlations between hyolaryngeal motions during swallowing in most of the subjects regardless of age and bolus type. The horizontal hyoid motion and laryngeal elevation were more strongly correlated with the epiglottic tilt than the vertical hyoid motion, which might suggest the mechanism of the epiglottic tilt during swallowing. The bolus volume and viscosity affected the correlation coefficients and time lags between the hyolaryngeal motions, particularly those related to the epiglottic tilt. The results suggest that cross-correlation analysis may be used for measuring the coordination and timing of swallowing. Further studies using cross-correlation analysis of additional physiological factors related to swallowing or pathological conditions are warranted.     

Effect of continuous swallowing on respiration

We examined the effect of continuous swallowing on breathing pattern and ventilation in 7 adult subjects. Repetitive swallowing was induced by oral infusion of water at a variable rate of 40, 60, 80 or 100 ml/min, while the subject breathed through the nose. The number of swallows increased from a mean of 5.2 (±2.7 SD) swallows/min during the control period to 9.2 ± 2.0 to 13.7 ± 2.9 swallows/min during infusion of 40 and 100 ml/min, respectively. The duration of interruption of breathing was bolus volume-dependent, increasing from 0.55 ± 0.99 sec with a mean bolus volume of 4.6 ± 1.4 ml to 0.87 ± 0.23 sec with a bolus volume of 8.1 ± 1.9 ml. The majority of swallows (73 ± 12%) interrupted breathing during inspiration. The mean tidal volume, inspiratory and expiratory times during swallowing periods were higher than those recorded during the control period, but the mean level of ventilation was not different from control, at all swallowing frequencies. Repetitive swallowing did not result in a single incidence of aspiration or coughing. We conclude that mechanisms integrating breathing and swallowing allow repetitive swallowing to occur without compromising ventilation, and that these mechanisms perfectly orchestrate between breathing and deglutition to prevent aspiration.     

Effects of Barium Concentration on Oropharyngeal Swallow Timing Measures

Videofluoroscopy is commonly used for evaluating oropharyngeal swallowing but requires radiopaque contrast (typically barium). Prior studies suggest that some aspects of swallowing, including timing measures of oral and pharyngeal bolus transit, vary depending on barium concentration. The aim of our study was to identify timing differences in healthy swallowing between “thin” (40 % w/v concentration) and “ultrathin” (22 % w/v concentration) barium solutions. Twenty healthy adults (Ten women; mean age = 31 years) each performed a series of three noncued 5-ml swallows each of ultrathin and thin liquid barium solutions in videofluoroscopy. Timing measures were compared between barium concentrations using a mixed-model ANOVA. The measures of interest were stage transition duration, pharyngeal transit time, and duration of upper esophageal sphincter opening. Significant differences were observed in the timing measures of swallowing with respect to barium concentration. In all cases, longer durations were seen with the higher barium concentration. Barium concentration influences timing parameters in healthy swallowing, even between ultrathin and thin concentrations. Clinicians need to understand and control for the impact of different barium stimuli on swallowing physiology.     

Clinical and videofluoroscopic evaluation of swallowing in 41 patients with neurologic disease.

Forty-one patients with neurologic disease (ND) were evaluated by clinical and videofluoroscopic examination of the oral cavity and pharynx to assess location and severity of swallowing dysfunction using various bolus consistencies. Four different materials were given to each patient, and included low- and high-viscosity barium suspensions, barium paste, and paste-coated cookie. Thirty-five patients had abnormalities of both oral and pharyngeal function. Four patients had pharyngeal dysfunction only, and two patients were normal. Mild swallowing difficulties occurred in five patients (12%), moderate dysfunction in 29 patients (71%), and severe dysfunction in five patients (12%). Thirty-two patients had pharyngeal stasis, which was symmetric in 30 patients (94%) and asymmetric in two. Site of stasis was not related to the type of neurologic disease. Fifteen patients aspirated, most of them (13 of 15) with the low-viscosity barium suspension. The predominance of aspiration with the low-viscosity liquid emphasizes the importance of clinical and videofluoroscopic evaluation of swallowing in dysphagic patients with ND for appropriate feeding recommendations. Thus, videofluoroscopy complemented the clinical examination and defined the type and severity of swallowing abnormalities and aspiration, when present.     

Videofluoroscopic Evaluation of Swallowing in Chagas�� Disease

Dysphagia is the most common digestive symptom reported by patients with Chagas’ disease. The condition results from abnormalities of esophageal motility. Our hypothesis is that there are also alterations of oral and pharyngeal transit during swallowing. We studied by videofluoroscopy the oral and pharyngeal transit during swallowing in 17 patients with dysphagia, a positive serologic test for Chagas’ disease, and radiologic demonstration of esophageal involvement. The study also included 15 asymptomatic healthy volunteers. Each subject swallowed in duplicate 5 and 10 ml of liquid and paste barium boluses. Chagas’ disease patients had a longer oropharyngeal transit with the 5-ml liquid bolus (p = 0.03), and a longer oral transit (p = 0.01) and pharyngeal transit (p = 0.04) with the 10-ml liquid bolus than controls. There was no difference between patients and controls with swallows of the 5-ml paste bolus. With swallows of the 10-ml paste bolus, the oropharyngeal transit (p = 0.05), pharyngeal transit (p = 0.04), pharyngeal clearance (p = 0.02), and UES opening (p = 0.01) took a longer amount of time in Chagas’ disease patients than in controls. We conclude that the duration of pharyngeal transit is longer in patients with Chagas’ disease than in normal subjects, especially with a bolus of pasty consistency and a volume of 10 ml.     

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.     

Normal solid bolus swallowing erect position

Individuals with structural and functional abnormalities of the esophagus are frequently symptomatic when swallowing solids and have been reported to demonstrate delay during nuclide examinations. This study was performed in symptomatic individuals to determine how often a solid bolus (13 mm barium tablet or 10 mm bagel bread sphere) passed through the esophagus without delay and whether erect solid bolus swallowing occurred without significant bolus hesitation during fluoroscopic evaluation. All individuals referred for an upper gastrointestinal examination or barium swallow who complained of dysphagia, heartburn, or chest pain were evaluated with a solid bolus. Individuals demonstrating gastroesophageal reflux, a hiatal hernia, a Schatzki B ring, or any esophageal motility disturbance were given a solid bolus. Twenty-six (27%) of 98 symptomatic individuals given a barium tablet had no delay in its passage. Thirteen (8%) of 150 symptomatic individuals given a bagel sphere had an erect solid bolus swallow with no delay in its passage. Only one individual of 26 given both solids (4%) showed no delay in transit of either bolus. Solid bolus swallows without delay were noted to occur in two ways: (1) The entire solid bolus passed in less than 3 s without delay of any kind, and (2) some temporary delay (less than 5 s) occurred at regions of anatomic esophageal narrowing (circopharyngeus, thoracic inlet, transverse aorta, left mainstem bronchus, or diaphragm). These temporarily delayed swallows were assisted by coincidentally swallowed fluid or the following peristaltic wave. No additional swallows were required to complete passage into the stomach. Bolus passage was accomplished predominantly by oral thrust, gravitational pull, esophageal relaxation, and possibly because of intraluminal esophageal pressure differentials. Therefore, solid bolus erect swallowing can occur without significant delay of bolus passage into the stomach in a symptomatic population. Opinions and assertions contained herein are those of the authors and do not represent the official position of the U.S. Navy, Uniformed Services University of the Health Sciences, or the Department of Defense.     

The Effect of Bolus Viscosity on Laryngeal Closure in Swallowing: Kinematic Analysis Using 320-Row Area Detector CT

The present study examined the effect of bolus viscosity on the onset of laryngeal closure (relative to hyoid elevation), the duration of laryngeal closure, and other key events of swallowing in ten healthy volunteers. All volunteers underwent 320-row area detector computed tomography swallow studies while swallowing 10 ml of honey-thick barium (5 % v/w) and thin barium (5 % v/w) in a 45° reclining position. Three-dimensional images of both consistencies were created in 29 phases at an interval of 0.10 s (100 ms) over a 2.90-s duration. The timing of the motions of the hyoid bone, soft palate, and epiglottis; the opening and closing of the laryngeal vestibule, true vocal cords (TVC), and pharyngoesophageal segment; and the bolus movement were measured and compared between the two consistencies. The result showed differing patterns of bolus movement for thin and thick liquids. With thin liquids, the bolus reached the hypopharynx earlier and stayed in the hypopharynx longer than with thick liquids. Among events of laryngeal closure, only the timing of TVC closure differed significantly between the two consistencies. With thin liquids, TVC closure started earlier and lasted longer than with thick liquids. This TVC movement could reflect a response to the faster flow of thin liquids. The results suggest that bolus viscosity alters the temporal characteristics of swallowing, especially closure of the TVC.     

Pressure-flow dynamics of the oral phase of swallowing

In 5 healthy volunteers, we studied the pressure-flow kinetics of the oral phase of swallowing. The regional profile within the oral cavity during swallowing was recorded, at the tongue tip (T₁), dorsum of the tongue (T₂), 3 cm from the tongue tip, oral floor, buccal cavity, and between the lips during swallows of water (0–20 ml) and 5 ml of mashed potato. Two strain gauge (SG) probes, each with two transducer recording sites 3 cm apart, were used for recording pressure. Supralingual and sublingual pressure were recorded concurrently. The relationship between transit of a barium bolus and deglutitive oral pressure phenomena was determined by concurrent videoradiography and manometry. Lingual pressure with the SG facing the tongue showed the most consistent recording and highest pressure: 193±16 (SE) mmHg at T₁ and 214±18 mmHg at T₂ for dry swallows. Pressures were similar for water swallows. However, mashed potato swallows produced a pressure of 383±30 mmHg at T₁ and 485±52 mmHg at T₂ that were greater than for water swallows (p<0.01). Pressure recorded with the transducers facing the hard palate and, to a lesser extent, laterally, was low and inconsistent. Oral-floor pressure was greatest with the transducers oriented upwards and averaged 64±2.9 mmHg proximally and 173±36 mmHg distally. At all sites the pressure waves propagated sequentially, toward the pharynx. Minimal pressure increases occurred in the buccal cavity. Lip squeeze varied from 0 to 90 mmHg. We can draw the following conclusions. The oral phase of swallowing includes contraction of the oral floor, which provides a platform for tongue movement. Oral pressure waves propagate toward the pharynx so that a swallowed bolus is propelled ahead of the point of lingual-palatal closure. Lingual peristalsis exhibits a wide range of pressures, with lower pressure for dry and liquid boluses than for a semisolid bolus. Buccal and lip contractions act as stabilizing forces, but do not contribute to bolus propulsion. Significant differences exist in the radial pressure profile of lingual peristalsis, with maximal pressure oriented toward the tongue.     

The Effect of Lateral Shift of Cricoid Cartilage on Pharyngeal Swallowing

Head rotation is widely used as one of the postural techniques for dysphagic patients. However, it cannot be used for patients with severe limitations to the range of motion of the neck. The purpose of this study was to determine the effect of applying pressure to the cricoid while swallowing and to explore the possibility of this maneuver as an alternative to head rotation. The swallowing function of 12 volunteers was examined with videofluorography under nine conditions: neutral, head rotated to the right, head rotated to the left, applying pressure to the cricoid on the right side at 5, 10, and 15 N, and applying pressure to the cricoid on the left side at 5, 10, and 15 N. To examine the effect of this maneuver on pharyngeal swallowing, the laterality of bolus flow was evaluated using 3 ml barium thin liquid from the posterior-anterior (P-A) view. The “pressing-cricoid” maneuver significantly altered the laterality of the bolus flow; the bolus flow was shifted to the side opposite to which the pressure was applied. The results of these changes were similar to those achieved with head rotation. These results demonstrated that the “pressing-cricoid” maneuver changes the bolus flow. This maneuver may have therapeutic value for the treatment of dysphagic patients as an alternative to head rotation.     

Timing of videofluoroscopic,manometric events,and bolus transit during the oral and pharyngeal phases of swallowing

The aims of this study were to evaluate and quantify the timing of events associated with the oral and pharyngeal phases of liquid swallows. For this purpose, we recorded 0–20 ml barium swallows in three groups of volunteers using videoradiographic, electromyographic, and manometric methods. The study findings indicated that a leading complex of tongue tip and tongue base movement as well as onset of superior hyoid movement and mylohyoid myoelectric activity occurred in a tight temporal relationship at the inception of swallowing. Two distinct general types of normal swallows were observed. The common “incisor-type” swallow began with the bolus positioned on the tongue with the tongue tip pressed against the upper incisors and maxillary alveolar ridge. At the onset of the “dipper-type” swallow the bolus was located beneath the anterior tongue and the tongue tip scooped the bolus to a supralingual location. Beginning with tongue-tip peristaltic movement at the upper incisors, the two swallow types were identical. Swallow events that occurred after lingual peristaltic movement at the maxillary incisors showed a volume-dependent forward migration in time that led to earlier movement of the hyoid and larynx as well as earlier opening of the upper esophageal sphincter in order to receive the large boluses that arrived sooner in the pharynx during the swallow sequence than did smaller boluses. The study findings indicated that timing of swallow events should be considered in reference to both swallow type and bolus volume. The findings also indicated an important distinction between peristaltic transit and bolus clearance.     

Preterm Infant Swallowing of Thin and Nectar-Thick Liquids: Changes in Lingual–Palatal Coordination and Relation to Bolus Transit

Tongue–soft palate coordination and bolus head pharyngeal transit were studied by means of postacquisition kinematic analysis of videofluoroscopic swallowing images of ten preterm infants referred from hospital NICUs due to poor oral feeding and suspicion of aspiration. Sequences of coordinated tongue–soft palate movements and bolus transits during swallows of thin-consistency and nectar-thick-consistency barium were digitized, and time series data were used to calculate continuous relative phase, a measure of coordination. During swallows of nectar-thick compared to thin barium, tongue–soft palate coordination was more likely to be antiphase, bolus head pharyngeal transit time was longer, and coordination was significantly correlated with bolus head pharyngeal transit. Analysis of successive swallows indicated that tongue–soft palate coordination variability decreased with nectar-thick but not with thin-consistency barium. Together, the results suggest that slower-moving bolus transits may promote greater opportunity for available sensory information to be used to modulate timing of tongue–soft palate movements so that they are more effective for pumping liquids.     

Breathing-swallowing interaction in neuromuscular patients: a physiological evaluation

RATIONALE: Malnutrition and aspiration are major problems in patients with neuromuscular disease. Because impaired swallowing contributes to malnutrition, means of improving swallowing are needed. OBJECTIVES: To investigate interactions between breathing and swallowing in neuromuscular disorders and to evaluate the impact of mechanical ventilation (MV) on swallowing in tracheostomized patients. METHODS: We studied 10 healthy individuals and 29 patients with neuromuscular disease and chronic respiratory failure (including 19 with tracheostomy). The tracheostomized patients who could breathe spontaneously were recorded during spontaneous breathing (SB) and with MV, in random order. MEASUREMENTS AND MAIN RESULTS: Breathing-swallowing interactions were investigated by chin electromyography and inductive respiratory plethysmography, using three water-bolus sizes (5, 10, and 15 ml) in random order. In contrast to healthy individuals, neuromuscular patients showed piecemeal deglutition with several swallows over several breathing cycles for each bolus. The percentage of swallows followed by expiration was about 50% in the patients compared with nearly 100% in the control subjects. The number of swallows and total swallowing time per bolus correlated significantly to maximal inspiratory pressure. In the 10 tracheostomized patients who were recorded both in SB and MV, the number of swallows and total swallowing time per bolus were significantly reduced during MV compared with SB. CONCLUSION: Neuromuscular patients showed abnormal breathing-swallowing interactions, which correlated to maximal inspiratory pressure. Moreover, MV improved the swallowing parameters in tracheostomized patients who were able to breathe spontaneously.     

Upper esophageal sphincter opening and modulation during swallowing

Studies were done on 8 normal subjects with synchronized videofluoroscopy and manometry to facilitate a biomechanical analysis of upper esophageal sphincter opening and volume-dependent modulation during swallowing. Movements of the hyoid and larynx, dimensions of sphincter opening, and intraluminal sphincter pressure were determined at 1/30th-s intervals during swallows of 1, 5, 10, and 20 ml of liquid barium. Our analysis subdivided upper esophageal sphincter activity during swallowing into five phases: (a) relaxation, (b) opening, (c) distention, (d) collapse, and (e) closure. Sphincter relaxation occurred during laryngeal elevation and preceded opening by a mean period of 0.1 s. Opening occurred as the sphincter was pulled apart via muscular attachments to the hyoid such that the hyoid coordinates at which sphincter opening and closing occurred were constant among bolus volumes. Sphincter distention after opening was modulated by intrabolus pressures rather than graded hyoid movement. The generation of intrabolus pressure coincided with the posterior thrust of the tongue that culminated in pharyngeal wall contact and the initiation of pharyngeal peristalsis. Larger volume swallows were associated with greater intrabolus pressure and increased bolus head velocity. The duration of sphincter opening increased in conjunction with a prolongation of the anterior-superior excursion of the hyoid and a delay in the onset of pharyngeal peristalsis (the event that determined the timing of sphincter closure). We conclude that transsphincteric transport of increasing swallow bolus volumes is accomplished by modulating sphincter diameter, opening interval, and flow rate (reflected by bolus head velocity). Furthermore, upper esophageal sphincter opening is an active mechanical event rather than simply a consequence of cricopharyngeal relaxation.     

Modulation of swallowing reflex by lung volume changes

We investigated the effects of changes in lung volume on coordination of respiration and swallowing in 11 healthy subjects. Swallowing reflexes were elicited by bolus injections of a small amount of distilled water (1 ml) and by continuous infusion of distilled water (3 ml/min) into the pharynx at three different levels of lung volume. The lung volume was changed by application of negative extrathoracic pressure (0, -20, and -40 cm H(2)O). We found that increases in lung volume prolonged the latency of swallows elicited by bolus injection of water and decreased the number of swallows during continuous infusion of water. In addition, the preponderant coupling of swallows with the expiratory phase observed before application of negative extrathoracic pressure was lost during application of negative extrathoracic pressure. These results may indicate that lung inflation has an inhibitory influence on the swallowing reflex, and modulates the timing of swallowing in reference to the respiratory cycle.     

Quantitative assessment of swallowing in healthy adults

Swallowing has hitherto been evaluated during physical examination, radiologic barium studies, manometry, and cervical auscultation. Radiography principally demonstrates qualitative aspects of oral and pharyngeal function, whereas quantitative aspects have primarily been documented by manometry. To evaluate swallowing quantitatively, without using invasive methods or radiation, we have applied a combined test of water drinking, i.e., the Repetitive Oral Suction Swallow test (ROSS). The test provides reliable measurements of suction pressure, bolus volume, timing of important events in oral and pharyngeal swallow, and respiration. The test is described and results from 292 healthy, nondysphagic subjects are presented. We found a mean bolus volume of 25.6±8.5 ml during single swallow and 21.1±8.2 ml during stress (forced, repetitive swallow). During forced, repetitive swallow, the bolus volume was more strongly associated with suction time (r²=0.55) than with peak suction pressure (r²=0.04), indicating that suction time is more important than suction pressure in determining the bolus volume. The oral-pharyngeal transit time decreased: single swallow 0.56±0.36 sec, forced repetitive swallow 0.23±0.11 sec, as did the coefficient of variation (48% and 64%, respectively) indicating a more automatic neural process for pharyngeal function in forced, repetitive swallow. The postswallow respiration started with inspiration in 10% of studied individuals, but did not correlate with deviations in other variables in the test. Thus, postswallow inspiration must be considered as normal. The ROSS test offers a rapid and easy quantitative assessment of swallowing.     

Swallowing in hereditary sensory ataxia

The oral, pharyngeal, and esophageal stages of swallowing were evaluated in 8 patients with recessively or dominantly inherited pure sensory ataxia. Six patients had swallowing difficulties: solid bolus obstruction, coughs during eating, and choking episodes. One patient had chronic bronchitis and another had recurrent pneumonia. The patients underwent a biphasic radiological barium swallow, including videofluoroscopy. No patient had a completely normal swallow. All had normal oral function, whereas pharyngeal function was abnormal in 6 patients. Esophageal function was abnormal in 6 patients. The swallowing dysfunction did not correlate with the severity of motor or sensory dysfunction in the limbs, nor with age or duration of ataxia. Our study shows that swallowing dysfunction is common in hereditary sensory ataxia. This dysfunction is likely to be due to involvement of the nucleus of the solitary tract in the brainstem. Despite some of the patients having suffered from choking episodes and others from bronchopulmonary complications, they did not spontaneously admit dysphagia. Swallowing should be evaluated thoroughly in patients with hereditary sensory ataxia since dysphagia in these patients might bring serious and potentially fatal complications.     

Dynamic aspects of lingual propulsive activity in swallowing

This investigation concerned the effect of different bolus volumes on the characteristics of lingual propulsive activity in swallowing. Young normal subjects were asked to perform dry swallows and swallows of 5, 10, and 15 ml of water. Tongue activity was recorded by tracking multiple gold pellets affixed to the tongue, utilizing the specialized research capabilities of the X-ray Microbeam facility at the University of Wisconsin. The major differences were between dry and liquid swallows, with dry swallows showing smaller range of movement, higher tongue position at the initiation of lingual propulsive activity, a slightly different direction of motion, a humped or flat rather than grooved cross-sectional contour of the tongue, lower peak velocity of motion, and slower progression of activity from tongue blade to dorsum. Within the 5–15 ml range of liquid bolus volumes, fewer consistent differences were found as a function of bolus size, and some marked individual differences in swallowing patterns were seen. Data are presented on normal within-subject variability in swallowing, with discussion of the possible contribution of sensory assessment of bolus size to the modification of oral and pharyngeal characteristics of swallowing.