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.     

The influence of bolus volume and viscosity on anterior lingual force during the oral stage of swallowing

The influence of bolus volume and viscosity on the distribution of anterior lingual force during the oral stage of swallowing was investigated using a new force transducer technology. The maximum force amplitudes from 5 normal adults were measured simultaneously at the mid-anterior, right, and left lateral tongue margins during 10 volitional swallows of 5-, 10-, and 20-ml volumes of water, applesauce, and pudding. Results indicated significant increases in peak force amplitude as viscosity increased. Volume did not significantly influence maximum lingual force amplitudes. Individual subjects demonstrated consistent patterns of asymmetrical force distribution across the lingual margins tested. The results suggest that bolus-specific properties influence the mechanics of oral stage lingual swallowing. This finding has important clinical implications in the assessment and treatment of dysphagic individuals.     

Effects of Bolus Volume on Pharyngeal Contact Pressure During Normal Swallowing

This cross-sectional study investigated the effect of bolus volume on contact pressure within the pharynx and upper esophageal sphincter (UES). Three solid-state manometric pressure sensors were placed transnasally into the pharynx and the proximal esophagus of 40 participants (gender equally represented and between the ages of 20 and 45 years). Participants completed five repetitions each of three swallowing conditions: 5-, 10-, and 20-ml water bolus swallows. Repeated-measures ANOVA revealed no significant differences in the amplitude of pharyngeal contact pressure between the three swallowing conditions (sensor 1: p = 0.627, sensor 2: p = 0.764). Similarly, for durational measures nonsignificant main effects were found at both sensor 1 (p = 0.436) and sensor 2 (p = 0.350). Significant differences were found in UES pressure between the three conditions of bolus swallows (p = 0.000), with negative pressure in the UES inversely proportionate to bolus volume. However, durational measures of UES relaxation pressure were not significantly different between all conditions (p = 0.473). This study demonstrates no significant pressure differences of amplitude and duration between swallowing conditions in the pharynx. At the level of the UES, smaller boluses generated greater negative pressure.     

Sounds of swallowing following total laryngectomy

Accelerometer transduced sounds of swallowing in total laryngectomees did not show acoustical differences for liquid vs paste swallows, as are found in normals. Compared with normal swallows, tongue propulsion of the bolus in laryngectomee swallows occurred closer in time to a distinctive spectral change associated with bolus flow into the esophagus. Interpretation stressed the lack of mechanical traction from laryngeal elevation contributing to pharyngoesophageal sphincter opening, and the increased role of tongue propulsion in laryngectomee swallows. Supported by grant no. CA 43838 from the National Cancer Institute     

Influence of Bolus Consistency on Lingual Behaviors in Sequential Swallowing

Thickened liquids are a commonly recommended intervention for dysphagia. Previous research has documented differences in temporal aspects of bolus transit for paste versus liquid consistencies; however, the influence of liquid viscosity on tongue movements during swallowing remains unstudied. We report an analysis of the influence of bolus consistency on lingual kinematics during swallowing. Electromagnetic midsagittal articulography was used to trace tongue body and dorsum movement during sequential swallows of three bolus consistencies: thin, nectar-thick, and honey-thick liquids. Rheological profiling was conducted to characterize viscosity and density differences among six liquids (two of each consistency). Eight healthy volunteers participated; four were in a younger age cohort (under age 30) and four were over the age of 50. The primary difference observed across the liquids of interest was a previously unreported phenomenon of sip-mass modulation; both flavor and density appeared to influence sip-sizing behaviors. Additionally, significantly greater variability in lingual movement patterns was observed in the older subject group. Systematic variations in lingual kinematics related to bolus consistency were restricted to the variability of downward tongue dorsum movement. Otherwise, the present analysis failed to find empirical evidence of significant modulations in tongue behaviors across the thin to honey-thick consistency range.     

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.     

Influence of Chin-down Posture on Tongue Pressure during Dry Swallow and Bolus Swallows in Healthy Subjects

The purpose of this study was to investigate the influence of chin-down posture and bolus size on tongue pressure during swallowing. Eleven healthy volunteers (7 men, 4 women; age range = 26–59 years) participated in the experiments. Tongue pressure during dry and 5- and 15-ml water swallows in neutral and chin-down postures was measured using a sensor sheet system with five measuring points on the hard palate. Sequential order, maximal magnitude, duration, and integrated value of tongue pressure at each measuring point were compared between postures and bolus sizes. Onset of tongue pressure at posterior-circumferential parts occurred earlier in dry swallow than in 5- and 15-ml water swallows in each posture. Chin-down posture was most effective for increasing tongue pressure in the 5-ml water swallow compared with dry swallow and the 15-ml water swallow, but it had almost no influence on tongue pressure with the 15-ml water swallow. These results suggest that chin-down posture increases the tongue driving force for small boluses in healthy subjects, which can be interpreted to mean that oropharyngeal swallowing in a chin-down posture requires more effort.     

Bolus Location at the Initiation of the Pharyngeal Stage of Swallowing in Healthy Older Adults

This study characterized the vertical position of the bolus head at the onset of the pharyngeal swallow in healthy older adults. Lateral-view videofluoroscopic (VF) images were obtained from ten healthy volunteers (age-71.6 ± 7.5 years, mean± SD) as they swallowed 5-cc thin liquid barium aliquots. For each swallow, the bolus head and several anatomic landmarks were digitally recorded from the image in which pharyngeal swallow-related hyoid bone elevation began. Vertical distance between the bolus head and the intersection of the tongue base and mandibular ramus (TMI) was computed. Bolus head position at swallow onset ranged from 47.4-mm above to 34.9-mm below the TMI (2.2 ± 14.4-mm, mean ± SD). Although the bolus head was below the level of the TMI for the majority of swallows, neither penetration nor aspiration occurred. For individual subjects, mean bolus head position ranged from 25.8 ± 5.0-mm above to 15.5 ± 6.5-mm below the TMI. Whereas five of ten subjects initiated the pharyngeal swallow with the bolus head consistently above or consistently below the TMI, five subjects initiated swallowing with the bolus head either above or below the TMI across trials. Older adults commonly initiate thin-liquid swallows with the bolus head well below the TMI without associated penetration or aspiration. Thus, bolus position alone does not differentiate between normal and pathologic swallowing within the healthy elderly. Bolus position at pharyngeal swallow onset can vary substantially from trial to trial within an individual, suggesting that the triggering of swallowing depends on multiple influences. This research was supported by NSERC grant No. 0GPO171208 and an Ontario Ministry of Health Career Scientist Award to REM.     

Age effects on the temporal evolution of isometric and swallowing pressure

BACKGROUND: The tongue plays a key role in bolus propulsion through the oropharyngeal chamber. In this study, possible age effects on the magnitude and timing of lingual pressure generation were analyzed. METHODS: Oral pressure was measured during isometric and swallowing tasks for 10 elderly (mean age = 81 years) and 10 young (mean age = 51 years) subjects. Three trials each of the isometric task and swallows of three different boluses (3 ml semisolid, 3 ml liquid, and 10 ml liquid) were performed by each subject. The timing and magnitude of isometric and swallowing pressure generation along with the pattern of the swallowing pressure waveform were analyzed. RESULTS: Whereas maximum lingual isometric pressures decreased with age (p < .001). no significant age difference was found for swallowing pressure. Time taken to reach peak pressure also was reduced with age in both the isometric task and swallows of liquid boluses (p < .05), while no significant age effect was found for semisolid swallows. Finally, only elderly subjects showed a pattern of liquid swallowing pressure generation in which multiple lingual gestures were required to reach peak pressure (termed "pressure building"), a pattern demonstrated by both young and elderly groups for semisolids. CONCLUSIONS: Decreased lingual strength with age combined with unchanging swallowing pressure leads to a decreased "pressure reserve," perhaps leaving older individuals more at risk for dysphagia resulting from insults directly or indirectly to the swallowing system. Additionally, swallowing is generally "slowed" with age, apparently due to both central and peripheral factors, and this change may have an impact on bolus flow outcomes.     

Coordinative Organization of Lingual Propulsion during the Normal Adult Swallow

Lingual propulsion during swallowing is characterized by the sequential elevation of the anterior, middle, and dorsal regions of the tongue. Although lingual discoordination underlies many swallowing disorders, the coordinative organization of lingual propulsion during the typical and disordered swallow is poorly understood. The purpose of this investigation was to quantitatively describe the coordinative organization of lingual propulsion during the normal adult swallow. Tongue movement data were obtained from the X-Ray Microbeam Database at the University of Wisconsin. Movement of four pellets placed on specific tongue regions were tracked in 36 healthy adult participants while they swallowed 10 cc of water across five discrete trials. The propulsive action of the tongue during bolus transport was quantified using a cross-correlation analysis. Lingual transit time (LTT), which was defined as the interval (lag time) between the movements of the anterior- and posterior-most tongue regions, was determined to be approximately 168 ms. The average time interval (lag) between the movements of the posterior tongue regions was significantly shorter than the intervals between more anterior tongue regions. The results also suggest that during bolus transport movement patterns of the anterior tongue regions are distinct from those of the posterior tongue regions. Future work is needed to determine if the absence of the observed coordinative organization of lingual propulsion is indicative of oral stage dysphagia.     

Surface Electromyography in Preoperative Evaluation and Postoperative Monitoring of Zenker’s Diverticulum

Patients with Zenker’s diverticulum (ZD) underwent surface electromyography (sEMG) evaluation to determine sEMG patterns specific for ZD. Group 1 comprised patients with proven long-standing ZD that refused surgical treatment (n = 11, age mean = 55.7 years). Group 2 comprised surgically operated on patients with ZD (n = 6, age mean = 61 years). The timing, amplitude, and graphic patterns of activity of the masseter, submental, and laryngeal strap muscles were examined during voluntary single water swallows (“normal”), single swallows of excessive amounts of water (20 ml, “stress test”), and continuous drinking of 100 cc of water. The muscle activity in pharyngeal and initial esophageal stages of swallowing was measured, and graphic records were evaluated in relation to timing and voltage. The data were compared with the previously established normative database. The main sEMG patterns of ZD are (1) duration of swallowing and drinking is longer than normal (p < 0.05), (2) electric amplitude of laryngeal strap muscles during swallowing activity is higher than normal (p < 0.05), and (3) regurgitation peaks immediately after swallow followed by secondary swallow of the regurgitated portion of a bolus as seen at the sEMG records are specific graphic patterns for the ZD. Zenker’s diverticulum has its own specific sEMG patterns. Surface EMG, being an important screening method for patients with dysphagia, is a valuable additional diagnostic tool for ZD. Because it is noninvasive and nonradiographic, it can be used for monitoring of long-standing cases of the disease as well as monitoring of postsurgical recovery.     

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.     

Swallowing Apnea as a Function of Airway Closure

The purpose of this research was to ascertain whether the existence of swallowing apnea (SA) was the sole result of glottic closure or the result of its own neural mechanism. Forty individuals served as participants. Groups 1 and 2 consisted of 10 individuals with laryngectomy less than one year and 10 individuals greater than one year, respectively. Groups 3 and 4 comprised 20 individuals who were age- and gender-matched to Groups 1 and 2. SA duration (SAD) was acquired during saliva swallows and 10-, 15-, 20-, and 25-ml water boluses. A repeated measures ANOVA was performed to determine mean differences in SAD as a function of group and bolus volume. Significant main effects of group and bolus volume were found and a significant interaction of group × bolus volume was found. In post-hoc analyses, both groups with laryngectomy exhibited statistically longer SADs than control groups. In single-df comparisons, the laryngectomy group over one year exhibited significantly shorter SADs on smaller versus larger bolus volumes. Even though SA is theoretically no longer needed in individuals with laryngectomy, the presence of SA remained in both groups with laryngectomy. Thus, these results support the hypothesis that SA is the result of its own neural command.     

Coordination of mastication and swallowing

The coordination of mastication, oral transport, and swallowing was examined during intake of solids and liquids in four normal subjects. Videofluorography (VFG) and electromyography (EMG) were recorded simultaneously while subjects consumed barium-impregnated foods. Intramuscular electrodes were inserted in the masseter, suprahyoid, and infrahyoid muscles. Ninety-four swallows were analyzed frame-by-frame for timing of bolus transport, swallowing, and phases of the masticatory gape cycle. Barium entered the pharynx a mean of 1.1 s (range −0.3 to 6.4 s) before swallow onset. This interval varied significantly among foods and was shortest for liquids. A bolus of food reached the valleculae prior to swallow onset in 37% of sequences, but most of the food was in the oral cavity at the onset of swallowing. Nearly all swallows started during the intercuspal (minimum gape) phase of the masticatory cycle. Selected sequences were analyzed further by computer, using an analog-to-digital convertor (for EMG) and frame grabber (for VFG). When subjects chewed solid food, there were loosely linked cycles of jaw and hyoid motion. A preswallow bolus of chewed food was transported from the oral cavity to the oropharynx by protraction (movement forward and upward) of the tongue and hyoid bone. The tongue compressed the food against the palate and squeezed a portion into the pharynx one or more cycles prior to swallowing. This protraction was produced by contraction of the geniohyoid and anterior digastric muscles, and occurred during the intercuspal (minimum gape) and opening phases of the masticatory cycle. The mechanism of preswallow transport was highly similar to the oral phase of swallowing. Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.     

Effects of Bolus Consistency on Timing and Safety of Swallow in Patients with Parkinson’s Disease

Aspiration pneumonia is the leading cause of death in Parkinson’s disease (PD) patients. In clinical practice, the videofluoroscopic examination (VFE) is the most common method for evaluation of swallowing disorders. One of the variables manipulated during the VFE is consistency of the bolus. The results of this examination greatly influence the recommendations made by speech-language pathologists regarding swallow therapy and/or intervention. The primary aim of this study was to investigate the effects of bolus consistency on penetration-aspiration (P-A) score and timing of swallow of persons with PD. The videoradiographic images of ten participants with PD swallowing six thin and six pudding-thick boluses were analyzed. Swallow timing and P-A were measured. (i.e., oral transit time, pharyngeal transit time, number of tongue pumps, and P-A score). The results demonstrated various significant differences and relationships among the dependent variables. Implications for further research and clinical practice are discussed.     

Durational aspects of oral swallow in neurologically normal children and children with cerebral palsy: An ultrasound investigation

Little data exist on the oral management of food boluses in neurologically normal children or children with cerebral palsy (CP). Twenty children with spastic CP and 20 neurologically normal children (age range: 6.2–12.9 years) were monitored with ultrasound imaging of the oral cavity during liquid and solid bolus tasks. A lip-cup contact detector synchronized to ultrasound image output was used during liquid tasks. Data collected from recorded ultrasound images were used to assess durational aspects of the oral phase of swallowing in neurologically normal children and children with CP. Coordinated analysis of ultrasound images with lip-cup contact data allowed timing of intervals in the pre-oral and oral phases of swallowing during liquid feeding tasks. Children with CP required more time than neurologically normal children for collection, preparation, oral transit, and total oral swallow time for 5-ml liquid boluses. Total oral swallow time was longer for solid bolus tasks in children with CP. Oral transit time for solid boluses was significantly longer than for liquid boluses in neurologically normal children and children with CP.     

Swallowing/ventilation interactions during oral swallow in normal children and children with cerebral palsy

Many children with cerebral palsy (CP) suffer from feeding disorders. Twenty children with spastic CP and 20 neurologically normal children (age range 6.2–12.9 years) were monitored with ultrasound imaging of the oral cavity synchronized with surface electromyographic (EMG) recordings of masseter and infrahyoid museles and respiratory inductance plethysmograph (RIP) recordings during feeding tasks. A lip-cup contact detector signaled contact of the drinking cup on the lip during liquid tasks. Children with CP required more time than normals for collection and organization of 5 ml and 75 ml liquid boluses for swallowing. The ventilatory preparation phase, recovery to baseline resting ventilatory pattern after swallowing, and total time for task completion were longer in children with CP for 5-ml and 75-ml tasks. The interval from lip-cup contact until alteration of ventilation from baseline resting ventilatory pattern was longer for children with CP during 75-ml tasks but not for 5-ml tasks. The interval from completion of the task-related cookie swallow until initiation of the next swallow was longer in children with CP than in normal children. These data provide evidence than children with CP manage solid boluses more easily than liquid boluses and small liquid boluses more easily than large liquid boluses. This investigation statistically confirms empirically based recommendations that children with CP be allowed more time to complete feeding tasks and consume small volume drinks rather than large volume drinks.     

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.     

Effects of Three Techniques on Maximum Posterior Movement of the Tongue Base

Effects of three techniques designed to improve maximum range of posterior movement of the base of tongue were investigated under videofluoroscopy in 20 subjects. Retraction of the tongue base during 3-ml pudding swallows, tongue pull-back, yawn, and gargle tasks was measured in millimeters, with the second cervical vertebra as a reference point and was judged subjectively as well. The gargle task was the most successful in eliciting most tongue base retraction for the group of subjects, although not in every subject. Gargle also resulted in greater tongue base movement than swallow more often than the other two voluntary tasks. Clinicians' subjective judgment of ``most' retracted tongue base position was generally reliable in comparison with actual measurements. The number of repeat swallows on each bolus correlated significantly with the approximate percentage of residue in the valleculae as judged clinically.     

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.