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.     

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.     

Effect of Tactile Stimulation on Lingual Motor Function in Pediatric Lingual Dysphagia

There is a scarcity of empirical evidence on effective treatments of swallowing dysfunction in young children who do not suck or swallow. There is no literature testing the effects of shaping a reflex or specifically shaping a swallow reflex. The purpose of this retrospective study was to investigate and isolate the specific regional mechanical functions of the tongue during swallowing. This study included 45 patients who did not swallow because of multiple congenital anomalies and gastroenterologic dysfunctions before and after corrective surgery and had histories of unsuccessful traditional feeding therapies. Evaluation included clinical gastroenterologic, nutritional, and neurologic examination, routine laboratory tests, and radiologic swallowing studies. A ten-year study analyzed the behavioral science procedures shaping both a swallow reflex and lingual surface geometry. Treatment variables were (1) a tactile stimulus to the posterior tongue and (2) sequential tactile stimuli to varied locations on the lingual surface. There were significant differences in lingual responses for all patients who were transferred from artificial feedings to independent prototypical swallowing capability and acquired oral consumption of recommended daily hydration and nutrition in 5-7 days of treatment. The initial tactile stimulus and six-level sequential stimuli resulted in six sequential lingual responses within each wavelike swallow reflex. Results of stimuli shaping varied lingual responses across 45 patients with severe multiple medical and anatomical deficits in swallowing, suggest that the etiology was not relevant in this population. These behavioral science approaches are novel treatment for pediatric lingual dysphagia.     

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.     

Lingual Discoordination and Dysphagia following Acute Stroke: Analyses of Lesion Localization

The mechanism and neural substrates that mediate lingual coordination during swallowing have not been well characterized. Although lingual discoordination during swallowing has been difficult to quantify, it has been defined as the random disorganization of anterior–posterior tongue movements evident in bolus propulsion. In a sample of consecutive acute stroke patients (n= 59), videofluoroscopic evaluation showed a 19% incidence of lingual discoordination during swallowing. Lingual discoordination during swallowing was not commonly associated with buccofacial apraxia, apraxia of speech, nor limb apraxia. Hemisphere and anterior–posterior localization did not predict occurrence of lingual discoordination. Lingual discoordination during swallowing occurred commonly in patients with subcortical lesions with the periventricular white matter (PVWM), the most common site of involvement. PVWM lesions may disconnect anterior and posterior cortical regions that are critical to oral control and coordination in swallowing, thereby producing lingual discoordination during swallowing. These data also suggest that the neural mechanisms that mediate lingual coordination may at least in part be independent of the neural systems that mediate buccofacial, limb, and speech praxis functions.     

Viscosity Is Not a Parameter of Postdeglutitive Pharyngeal Residue: Quantification and Analysis with Scintigraphy

The aim of this study was to explore the influence of viscosity on pharyngeal residue in normal healthy volunteers. Scintigraphy was used to measure pharyngeal residue in 11 healthy volunteers after swallowing three different substances (age = 20.2–48.3 years). The first substance was a 10-ml solution of tap water with 0.5% xanthan with a viscosity of 4500 mPa s, comparable to a yogurt drink. The second and third substances were a 0.75% xanthan and a 1.00% xanthan solution, with viscosities of 10,500 and 21,000 mPa s, comparable to low-fat yogurt and 3% fat yogurt, respectively. Tap water was used as the control substance. Mean pharyngeal residue after swallowing tap water was 2.3% (SD = 1.2) of the initial volume in the oral cavity. Pharyngeal residue after swallowing 0.5% xanthan solution was 1.8% (SD = 0.8), after swallowing 0.75% xanthan solution 2.6% (SD = 2.2), and after swallowing 1.00% xanthan solution 2.8% (SD = 1.7). No significant correlation between increase of viscosity and pharyngeal residue was found. In healthy persons viscosity does not seem to be a significant parameter for pharyngeal residue for boluses with viscosities ranging from tap water to solutions having a viscosity comparable to 3% fat yogurt.     

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.     

Swallowing Apraxia: A Disorder of the Praxis System?

The purpose of this review is to evaluate the disorder of swallowing apraxia and determine how it fits into the praxis system. Swallowing apraxia, a proposed disorder of lingual, labial, and mandibular coordination, has been observed before bolus transfer during the oral stage of swallowing. Although frequently discussed anecdotally in dysphagia literature, the possible mechanisms and neural networks of swallowing apraxia have not been elucidated. Similarities and differences of swallowing apraxia with buccofacial, speech, and limb apraxias are evident. Critical review of the literature has identified possible similarities as greater occurrence upon command, transitive nature of the action, and evidence of spatial errors. Conversely, differences such as hemispheric lateralization and multiple gesture assessment may exist between swallowing apraxia and more traditional forms of apraxia. Until discrete error patterns of swallowing apraxia are identified and precisely measured, the nature of this disorder and its relationship with the praxis system will continue to remain elusive.     

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.     

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.     

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.     

Chewing and the dimension of the pharyngoesophageal segment

Masticatory efficiency was evaluated in 21 adults for four chewing parameters: mixing of a color-patterned chewing gum mass, shaping of a chewing gum mass, particle reduction of a silicone tablet, and number of chewing strokes before the first swallow of an almond. The results of these tests were correlated with the dimension of the pharyngoesophageal (PE) segment during swallow of liquid barium and solid meat. The transverse width of the PE segment during swallow of liquid barium correlated significantly with the chewing parameters. The sagittal width of the PE segment during swallow of liquid barium correlated only weakly with the chewing parameters. The PE segment dimension during swallow of a solid meat bolus did not correlate with the chewing parameters. The results suggest that there is feedback during chewing and swallowing between the PE segment and the oral cavity.     

Using ultrasound to investigate intrapersonal variability in durational aspects of tongue movement during swallowing

The purpose of this study was to determine the extent of intrapersonal variability in durational aspects of tongue movement during swallowing. Using ultrasound, the entire duration of tongue movement and the duration of the oral transport stage during swallowing was measured in a group of patients with neurogenic swallowing disorder and a group of matched healthy control subjects. The results indicate considerable intrapersonal variability in both groups. The patient group performed significantly more variably in terms of the duration of the transport stage. However, when looking at individual results, this finding can not be generalized, in that some patients showed rather decreased variability. Other differences between patient the group and control subjects were not statistically significant. Ultrasound was found to be a highly suitable technique for the purpose of this study.     

Measuring Intraoral Pressure: Adaptation of a Dental Appliance Allows Measurement During Function

This article introduces a new way of recording intraoral pressures from a range of locations within the oral cavity. To measure pressure flow dynamics during swallowing, we fitted eight miniature pressure transducers capable of measuring absolute pressures to a chrome-cobalt palatal appliance with a labial bow. Unlike previous devices, our design provides a rigid, custom-fitted platform for the simultaneous recording of pressures at eight locations within the oral cavity during function. We placed an anterior pair of gauges to measure lingual and labial contact against the left central incisor tooth, and two pairs of gauges to measure pressure contributions of the lateral tongue margin and cheeks on the canine and first molar teeth. Finally, lingual pressure on the midline of the palate was measured by two gauges, one at the position of the premolars and one on the posterior boundary of the hard palate. We then recorded intraoral pressures in five adult volunteers seated in an upright position and asked to swallow 10 ml of water. Labial pressures on the canine rose rapidly from a resting level of 10 kPa to 33 kPa, while pressure profiles from the labial aspects of the incisor and first molar teeth followed a negative pattern, peaking at -12 kPa for the incisor and -15 kPa for the molar sensor. Pressure profiles recorded from the palatal aspects of the first molar and the canine appeared to be similar, but the former fell to -13 kPa before rising to 9 kPa, and the canine pressure rapidly increased to 22 kPa before returning to its resting level of 4 kPa. The pressure profile of the palatal aspect of the central incisor was strikingly different; at the start of the swallow, pressure dropped precipitously to -20 kPa, before slowly rising to 10 kPa. It then followed the general pattern of the other two sensors, before peaking again at 10 kPa and then returning to a resting level of 4 kPa. We also showed that there were significant negative pressures in the mouth during function, and that pressure profiles varied markedly between individuals.     

Quantitative aspects of swallowing in an elderly nondysphagic population

The prevalence of swallowing impairment increases with age and is a major health care problem in the elderly. It has been assumed that age-related changes in nerves and muscles hamper muscle strength and coordination of swallowing. However, it is unclear what impairment is related to primary aging and what is the consequence of diseases prevalent in the elderly (secondary aging). In order to quantify swallowing in nondysphagic elderly we used the noninvasive ROSS (Repetitive Oral Suction Swallow) test. A total of 53 individuals aged 76±5 years (mean±SD) were examined. We found that the nondysphagic elderly demonstrated significant differences compared with young individuals in 10 of 17 measured variables, i.e., decreased peak suction pressure, increased frequency of multiple swallows after one ingestion, increased frequency of polyphasic laryngeal movements, increased frequency of inspiration after swallowing, and increased frequency of coughing during or after swallowing. Therefore, primary aging mainly seems to influence coordination of swallowing, but oral and pharyngeal swallow per se seem to be unaffected.     

Videofluoroscopic evaluation of patients with Guillain-Barré syndrome

We reviewed 14 patients with clinically confirmed Guillain-Barré syndrome for swallowing dysfunction. All had swallowing dysfunction varying from mild to severe. Six patients (43%) had equivalent impairment during oral and pharyngeal phases. Seven patients (50%) had more severe functional abnormalities during the pharyngeal phase than during the oral phase. One patient (7%) had moderate disorder during the oral phase and mild disorder during the pharyngeal phase. Thirty-six percent of the patients had moderate-to-severe dysfunction during the oral phase, and 71% had moderate-to-severe dysfunction during the pharyngeal phase. In 5 patients who had multiple sequential examinations, moderate or severe swallowing disorders improved to mildto-moderate disorders within 4–8 weeks after the onset of the symptoms. Residual swallowing disorders may be seen in those who had severe swallowing dysfunction during the later phases of their disease. Further investigations are needed to determine if swallowing abnormalities persist after complete recovery from Guillain-Barré syndrome.     

Quantitative assessment of oral and pharyngeal function in Parkinson's disease

Oral and pharyngeal dysfunction is common in Parkinson's disease. To reveal the frequency of swallowing dysfunction and correlate swallowing dysfunction with locomotor disturbances, we studied 75 patients with Parkinson's disease staged I–IV according to the Hoehn and Yahr score. We assessed oral and pharyngeal swallow during optimal medication by a quantitative test of swallowing (the ROSS test) measuring the suction pressure, bolus volume, swallowing capacity, and time for important events in the swallowing cycle. We found abnormal results in 7/12 patients (58%) in stage 1 of the Hoehn and Yahr score, in 13/14 patients (93%) in stage 2, in 29/32 patients (91%) in stage 3, and in 16/17 patients (94%) in stage 4. Abnormal test results in stages, 1, 2, and 3 were seldom related to swallowing difficulties noticed by the patients. In advanced disease (Hoehn and Yahr stage 4), the abnormal results were often considerable, with swallowing difficulties obvious to the patient. Two of 17 patients coughed during or immediately after the test and 3/17 patients were unable to complete the test. The degree of swallowing disturbance increased during stress (forced, repetitive swallow). The Hoehn and Yahr score and the results in the ROSS test did not correlate, indicating that swallowing disturbances are due to nondopaminergic degeneration. Silent swallowing impairment may interfere with the nutrition and quality of life in Parkinson's disease, thus it is of interest to monitor this in clinical practice.     

The Effects of Intraoral Pressure Sensors on Normal Young and Old Swallowing Patterns

Lingual pressure generation plays a crucial role in oropharyngeal swallowing. To more discretely study the dynamic oropharyngeal system, a 3-bulb array of pressure sensors was designed with the Kay Elemetrics Corporation (Lincoln Park, NJ). The influence of the device upon normal swallowing mechanics and boluses representative of flow relative to age and bolus condition was the focus of this study. Twelve healthy adults in two age groups (31 ± 5 years, 2 males and 4 females, and 78 ± 7 years, 2 males and 4 females) participated. Each subject was instructed to swallow four boluses representative of conditions with and without three pressure sensors affixed to the hard palate. Postswallow residue at four locations, Penetration/Aspiration Scale scores, and three bolus flow timing measures were assessed videofluoroscopically with respect to age and bolus condition. The only statistically significant influences attributable to the presence of the pressure sensors were slight increases in residue in the oral cavity and upper esophageal sphincter with some bolus consistencies, 8% more frequent trace penetration of the laryngeal vestibule predominantly with effortful swallowing, and variances in oral clearance duration. We conclude that the presence of the pressure sensors does not significantly alter normal swallowing patterns of healthy individuals. This article is GRECC No. 03-01. This work was supported by NIH Grant NS24427 and VA Grant E727-2RA.     

The Effect of Taste and Palatability on Lingual Swallowing Pressure

There is evidence that a strong, unpalatable, sour bolus improves swallowing in neurogenic dysphagia. It is not known whether other tastes may alter swallowing physiology. This study investigated the effect of moderate versus high taste concentrations (sweet, sour, salty, bitter) and barium taste samples on lingual swallowing pressure in ten healthy young adults, using a three-bulb lingual pressure array secured to the hard palate. Palatability of the samples was analyzed using the nine-point hedonic scale. Results showed that moderate sucrose, high salt, and high citric acid elicited significantly higher lingual swallowing pressures compared with the pressures generated by water. Pressures in the anterior bulb were significantly higher than those recorded from the middle or posterior bulb. There was no significant effect of palatability on lingual swallowing pressures. High salt and citric acid are known to elicit chemesthesis mediated by the trigeminal nerve. These results suggest that chemesthesis may play a crucial role in swallowing physiology. If true, dysphagia diet recommendations that include trigeminal irritants such as carbonation may be beneficial to individuals with dysphagia. However, before this recommendation more research is needed to examine how food properties and their perception affect swallowing in individuals with and without dysphagia.This research was supported by Syracuse University.