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.     

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.     

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.     

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.     

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.     

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 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.     

Dysphagia after pharyngolaryngeal cancer surgery. Part I: Pathophysiology of postsurgical deglutition

Eighty-one patients were examined after laryngopharyngeal cancer surgery with a sequential computer manometry system using 4-channel-pressure probes. The general swallowing coordination is neither a matter of the oropharyngeal pressure thrust nor of the pharyngeal transit time, but mainly depends on swallowing initiation. The points of interest are both the pharyngeal inlet and outlet. The topographic correlates are the base of the tongue and the upper esophageal sphincter (UES). Resections of the base of the tongue lead to a decrease of volume available for pressure generation, thus reducing the tongue driving force. The swallowing reflex is uncoordinated resulting in dyskinesia of the UES. Compensation may be achieved with a stronger oropharyngeal thrust and/or repeated swallows. Distal resections alter the pharyngoesophageal segment so that a functional obstruction results, combined with lower pressure amplitudes in the hypopharynx, reducing the pressure gradient necessary for bolus flow. This increasing resistance can be overcome by higher propulsive forces in the base of the tongue region. In case of additional lingual defects, deglutition is subject to decompensation, highlighting the major role of the tongue as a pressure generator for bolus passage.     

Durational aspects of the oral-pharyngeal phase of swallow in normal adults

We present durational data on normal oral-pharyngeal swallows in adults obtained using ultrasound imaging. The effects of normal aging on the oral-pharyngeal phase of swallowing were studied in 47 healthy adults. Timing of the oralpharyngeal phase of swallow was determined from frame-by-frame analysis of ultrasound videos of the motion of the tongue and hyoid bone from initial rest to final resting position. Duration of unstimulated (dry) swallows was compared to stimulated (wet) swallows across four age groups and by sex and age. For most subjects, dry swallows were longer than wet swallows; moreover, swallow duration was longest for older women than any other group. As age increased (55+), oral swallows were accompanied by extralingual gestures. Ability to produce a timed series of continuously dry swallows was somewhat influenced by age. Findings are suggestive of an age change more typical in women, with a pattern of multiple lingual gestures commonly seen after age 55 in both sexes. We suggest that subtle, subclinical, oral neuromotor changes occur with normal aging to cause these findings.     

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.     

Tongue Pressure Patterns During Water Swallowing

Bolus propulsion during the normal oral phase of swallowing is thought to be characterised by the sequential elevation of the front, middle, and posterior regions of the dorsum of the tongue. However, the coordinated orchestration of lingual movement is still poorly understood. This study examined how pressures generated by the tongue against the hard palate differed between three points along the midline of the tongue. Specifically, we tested three hypotheses: (1) that there are defined individual patterns of pressure change within the mouth during liquid swallowing; (2) that there are significant negative pressures generated at defined moments during normal swallowing; and, (3) that liquid swallowing is governed by the interplay of pressures generated in an anteroposterior direction in the mouth. Using a metal appliance described previously, we measured absolute pressures during water swallows in six healthy volunteers (4 male, 2 female) with an age range of 25–35 years. Participants performed three 10-ml water swallows from a small cup on five separate days, thus providing data for a total of 15 separate water swallows. There was a distinct pattern to the each of the pressure signals, and this pattern was preserved in the mean obtained when the data were pooled. Furthermore, raw signals from the same subjects presented consistent patterns at each of the five testing sessions. In all subjects, pressure at the anterior and hind palate tended to be negative relative to the preswallow value; at mid–palate, however, pressure changes were less consistent between individuals. When the pressure differences between the sites were calculated, we found that during the swallow a net negative pressure difference developed between anterior and mid-palate and a net positive pressure difference developed between mid-palate and hind palate. Large, rapid fluctuations in pressure occurred at all sites and these varied several-fold between subjects. When the brief sharp reduction in pressure that occurred early in each swallow was used to determine the sequence of events, we found that activity occurred first at the anterior of the palate followed by the mid-palate and then the hind palate. There was a considerably longer and more variable delay between the start of activity at the front of the palate than at the rear of the palate. To obtain an index of the “effort” involved in generating the pressures at each site regardless of direction (positive or negative), we obtained the product of the root mean square (RMS) pressure change during each swallow (kPa) and its duration (s). Overall, the most effort appears to have occurred at the front of the palate and the least at mid-palate. Our results also showed that some participants exerted a small amount of midline pressure when swallowing, while others used a relatively large amount of tongue pressure. We conclude that while tongue behaviour during swallowing follows a classical sequence of rapid shape changes intended to contain and then propel the bolus from the oral cavity to the pharynx, there is a large range of individual variability in how this process is accomplished.     

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.     

A new application for electropalatography: Swallowing

Electropalatography (EPG) has been applied to linguistic research and speech pathology. This study evaluated whether EPG could provide useful information on swallow-related tongue action. Specifically, the investigation focused on the quantification of tongue-palate contact patterns for swallowing and on the effects of bolus volume and consistency. Five normal subjects were tested during swallows of 5 and 30 ml of water, 5 and 30 ml of gelatin, and saliva. By segmenting the EPG time-motion sequences into four stages (prepropulsion, propulsion, full contact, withdrawal) and compartmentalizing the palate into six bins (front, central, back, lateral, medial, midline), temporal and spatial characteristics of deglutitive tongue-palate contact were revealed. Significant differences (p<0.01) were found in contact timing across bolus sizes and consistencies for the propulsion and full contact stages. Water was propelled faster than gelatin, and 30-ml gelatin faster than 5-ml gelatin. Dry swallows had a longer full contact stage than water. Contact patterns, though not statistically analyzed at this time, appeared to vary little as a function of bolus properties. Our findings suggest potential value in using EPG to investigate the timing and patterning of abnormal tongue movements associated with disordered swallowing.     

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.     

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.     

Correlation of ultrasound imaging of oral swallow with ventilatory alterations in cerebral palsied and normal children: Preliminary observations

Preliminary results of an investigation that synchronizes the videotaped output of a ultrasound camera and the analog data from physiological measurements of swallowing and ventilation in normal and cerebral palsied (CP) children are presented. Four cerebral palsied children and three control children undertook a single sip-swallow of 5 ml of liquid and a solid mastication-swallow sequence on three occasions according to a defined protocol. The CP children exhibited much more variability and less control of the liquid bolus than did the controls. The ultrasound image clearly demonstrates the lack of control of the posterior of the tongue in many CP children. Some parts of the sequence of oral swallow and the time to achieve maximum anterior displacement of the hyoid bone appear to be slowed. The sequential events of swallowing show less variability as the sip-swallow proceeds from the oral voluntary to pharyngeal and lower involuntary phases. This study also identified a short-latency apnea that appears to accompany a saliva (protective) swallow and a long-latency apnea that accompanies semisolid or liquid bolus (alimentary) swallows. Further investigations of normal and CP children utilizing a combined diagnostic imaging-physiological measurement approach will follow this initial study.     

Velar activity and timing of eustachian tube function in swallowing

Velar motion for dry and liquid swallows was investigated. as well as velar activity in speech, based on X-ray microbeam pellet tracking data. Electromyographic recordings for tensor and levator veli palatini were obtained simultaneously. Velar pellet trajectories for swallowing were more complex than for speech, since there was a highvelocity anterior component in swallowing. For some swallows this anterior component was integrated with velar elevation (especially in liquid swallows), but in other cases initial velar elevation occurred considerably earlier (chiefly in dry swallows). The burst of tensor and levator veli palatini activity characteristic of swallowing was associated with the anterior component of velar pellet motion, but not consistently with velar elevation per se. The conventional view on timing of tensor veli palatini contraction in a swallow, which governs Eustachian tube opening, is that this is associated with velar closure. The X-ray microbeam data suggest rather that Eustachian tube ventilation is more closely associated in time to the onset of pharyngeal peristalsis, which may or may not coincide with initial velar elevation. This work was supported by the National Institutes of Health under grant no. NS-16373 (NINCDS) and grant no. CA-43838 (NCI).     

健康老年妇女吞咽功能的研究

目的　通过电视X线透视吞咽功能的研究 ,评价健康老年妇女液体吞咽运动 ,并对液体吞咽运动的影响因素进行分析。　方法　 4 0例健康老年妇女 ,老年前期组 (5 0～ 5 9岁 ) 2 0例 ;老年组 2 0例 ,年龄 6 0～ 79岁。进行电视X线透视液体吞咽功能检查 ,分别对口咽部相关结构进行运动学分析 ,比较不同液体食团体及年龄对健康老年妇女吞咽的影响。　结果　 (1 )老年组较老年前期组渗透、口咽部滞留发生率增高 ,两组渗透发生率分别为 :7 5 %、3 8% ;口腔滞留发生率分别为 :1 2 5 %、6 3% ;咽腔滞留发生率分别为 :2 6 5 %、1 7 5 % ;口咽传递时间、腭咽部关闭时间及环咽部开放时间延长 (均为P <0 0 5 ) ;喉、舌骨向上运动距离增大 (P <0 0 5 )。 (2 ) 1 0ml食团较 1ml渗透、口咽部滞留发生率增高 ,两组渗透发生率分别为 :8 8%、2 5 % ;口腔滞留发生率分别为 :1 3 8%、5 0 % ;咽腔滞留发生率分别为 :31 3%、1 3 8% ;口传递时间缩短而环咽部开放时间延长 (均为P <0 0 5 ) ;喉向上、前运动 ,舌骨向前、向上运动的距离增大 (P <0 0 5 )。　结论　临床应用电视X线透视吞咽功能检查并对口咽期吞咽功能进行运动学分析是可行的 ;年龄及食团体积均影响健康老年妇女的液体吞咽功能     

Age-Related Differences in Pressures Generated During Isometric Presses and Swallows by Healthy Adults

The aim of this prospective observational study was to determine the associations among age, maximum lingual isometric pressures, and maximum swallow pressures in specific regions of the tongue. Individuals 21 years and older who reported normal swallowing were enrolled. Seventy-one healthy adults were stratified by age into young (21–40 years), middle (41–60), and old (61–82) groups. Maximum pressures were measured for each individual during isometric tongue press tasks as well as saliva, 5, and 10 mL thin liquid bolus swallows at 5 sensors located on the hard palate: front, middle, left, right, and back. Lower maximum lingual pressures for all tasks were associated with increased age (p < 0.04). Saliva pressures exhibited a different pressure pattern than bolus swallows with pressures higher than bolus swallows on middle (p < 0.03) and back (p < 0.05) tongue sensors but not in the front. Diminished swallow pressure reserve (maximum isometric pressure–maximum swallow pressure) also was found with increased age (p < 0.03). Isometric pressures were greater than swallow pressures in young and middle age groups at both the front (p < 0.04) and back (p < 0.03) sensors, but only significantly greater at the front sensor for the oldest group (p < 0.04). Older healthy adults have lower lingual isometric pressures and lower swallow pressures than younger healthy adults. Elders have a decreased swallow pressure reserve to draw upon during occasions of physiological stress. While the exact mechanisms for age-related decline in lingual pressures remain unclear, they are likely due, at least in part, to sarcopenia. Saliva, 5, and 10 mL thin boluses also exhibit different age-related declines in pressure at specific sensors, indicating they may elicit different muscle activation patterns.     

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.