A Comparison of Lingual Pressure Generation Measures Using Two Devices in Community-Dwelling, Typically Aging Adults: An Important Clinical Implication.

DESIGN: A multisite, prospective, and randomized within-subject design study. SETTING: Five university settings in varied geographical areas in the United States. PURPOSE: The purpose of this study was to compare lingual pressure generation using the Tongueometer (TO) and the Iowa Oral Performance Instrument (IOPI) in typically aging, community-dwelling adults during three measurement tasks: maximum isometric pressure (MIP), regular effort saliva swallow (RESS) pressure, and effortful saliva swallow pressure (ESP). PARTICIPANTS: Eighty-seven typically aging, community-dwelling adults (aged 55 years and over) with no self-reported history of swallowing or neurological disorders were recruited to complete this study. RESULTS: Strong positive associations were found between the lingual pressure generation measures from the TO and IOPI in all tasks in typically aging adults, with Pearson correlations ranging from r = .780 to .874, p < .001. Agreement between the devices (Lin's concordance correlation coefficient) ranged from moderate for the MIP (ρc = .78) and ESP (ρc = .61) tasks to weak agreement for the RESS task (ρc = .47). MIP, RESS pressure, and ESP were lower when measured by the TO compared with the IOPI, p < .001. CONCLUSIONS: The TO measures lingual pressure generation similarly to the IOPI but pressures register lower when using the TO than the IOPI in typically aging persons. This supports the need for developing normative values specific to the TO device or development of a valid and reliable conversion formula from TO to IOPI normative values. At this time, the clinical use of reference values from the TO should not be generalized to IOPI normative values.

Flexibility for Intensity Dosing in Lingual Resistance Exercises: A Large Randomized Clinical Trial in Typically Aging Adults as Proof of Principle.

OBJECTIVE: The objective of this study was to determine the effect of intensity dosing during tongue exercise on tongue pressure generation, adherence, and perceived effort. DESIGN: This was a five-site, prospective, randomized clinical trial. Outcome measures were obtained across multiple baselines, biweekly during exercise, and 4-weeks post-intervention. SETTING: The general community at each study site. PARTICIPANTS: Typically aging adults between 55-82 years of age with no history of neurological or swallowing disorders. Eighty-four volunteers completed the study. INTERVENTIONS: Participants were randomly assigned to one of four exercise groups: (a) maximum intensity/no biofeedback, (b) progressive intensity/no biofeedback, (c) maximum intensity/biofeedback, and (d) progressive intensity/biofeedback. Half of the participants completed a maintenance exercise program. OUTCOME MEASURES: Maximum isometric pressure (MIP), regular effort saliva swallow pressure, adherence, and the Borg Rating of Perceived Exertion Scale. RESULTS: All exercise protocols were efficacious for gains in MIP (large effect sizes; Cohen's d). Group 3 made gains in regular effort saliva swallow pressure (medium effect size). There was a significant change in perceived exertion for regular effort saliva swallow pressure at 8 weeks. Tongue pressure gains were maintained at 1 month, regardless of maintenance group status. Mean adherence across groups was high. CONCLUSIONS: All groups improved pressure generation. Intensity dosing differences did not affect strength gains, adherence, or detraining. Regular effort saliva swallow pressure may be most responsive to maximum intensity with biofeedback. The findings suggest flexibility in approach to tongue exercise protocols. Tongue muscles may differ from limb muscles in terms of dose response and neuroplasticity principles.

Dysphonia Outperforms Voice Change as a Clinical Predictor of Dysphagia.

PURPOSE: Changes in voice quality after consuming food or drink have been used as a clinical indicator of dysphagia during the clinical swallowing evaluation (CSE); however, there is conflicting evidence of its efficacy. This study investigated if dysphonia and/or voice change after swallowing are valid predictors of penetration, aspiration, or pharyngeal residue. Our approach aimed to improve current methodologies by collecting voice samples in the fluoroscopy suite, implementing rater training to improve interrater reliability and utilizing continuous measurement scales, allowing for regression analyses. METHOD: In this prospective study, 30 adults (aged 49-97 years) referred for a videofluoroscopic swallowing study (VFSS) were audio-recorded completing a sustained /i/ prior to VFSS and again after swallowing each bolus during the VFSS. Swallowing function was measured using the reorganized Penetration-Aspiration Scale and the Normalized Residue Ratio Scale. Following listener training, 84 voice samples were perceptually rated using the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). Ordinal and logistic regression were used to determine whether voice quality and voice quality change after swallowing were predictors of airway invasion and pharyngeal clearance. RESULTS: Results indicated that the presence of dysphonia at baseline during a sustained /i/ task as measured by the CAPE-V predicted airway invasion but not pharyngeal residue. Voice change after swallowing associated with vowel /i/ production as measured by the CAPE-V did not predict either dysphagia measure. CONCLUSION: These results indicate that voice change during a sustained /i/ after swallowing appears unrelated to airway invasion or pharyngeal residue; however, in the absence of known laryngeal pathology, dysphonia prior to a CSE should alert speech-language pathologists of a possible comorbid dysphagia.

The Influence of Side-Lying Position on Oropharyngeal Swallow Function in At-Risk Infants: An Exploratory Study.

This investigation assessed the effect of side-lying position on infant oropharyngeal swallow physiology. Infant modified barium swallow studies (MBS) recordings were retrospectively examined in matched-pairs comparing at-risk infants swallowing in both an upright/cradled position and a side-lying position. Swallow parameters were measured independently and through a consensus coding approach. Infants fed in side-lying position showed a decrease in airway invasion severity as compared with when those same infants were fed in an upright/cradled position (P = .009). Bolus location at the time of swallow initiation was higher when infants were fed in side-lying position as compared with cradle position (P = .024), representing decreased risk of airway invasion. Infants fed in side-lying position demonstrated fewer swallows per breaths (P = .032). This pilot study validates the need for additional research to further define the mechanisms related to this improvement, and to determine how diagnosis and medical stability moderate these findings.

The Feasibility of Home-Based Treatment Using Vibratory Stimulation in Chronic Severe Dysphagia.

PURPOSE: Previously, externally placed vibratory laryngeal stimulation increased rates of swallowing in persons with and without dysphagia. This study examined the feasibility of using a vibratory device on the skin over the thyroid cartilage for home-based swallowing rehabilitation in long-standing dysphagia. METHOD: Only participants with long-standing dysphagia (> 6 months) following cerebrovascular accident or head/neck cancer who had not previously benefited from dysphagia therapy participated. The device had two modes used daily for 90 days. In automatic mode, participants wore the device when awake, which vibrated for 4-8 s every 5 min to trigger a volitional swallow. In manual mode, participants practiced by activating vibration while swallowing rapidly. Study-related adverse events, such as pneumonia, and device-recorded adherence were tracked. Swallowing function on a modified barium swallow study was assessed at baseline and after 3 months of device use. Outcome measures included the Dysphagia Outcome and Severity Scale (DOSS), Penetration-Aspiration Scale (PAS), and swallowing timing measures. Participants' perceptions of the vibratory device and training were obtained. RESULTS: The intent to treat analysis showed seven of 11 participants completed the study, all with severe chronic dysphagia. Of those seven participants completing the study, two developed respiratory complications (possibly due to pneumonia) that cleared after antibiotic intervention. For prescribed practice trials, adherence was 80% or greater in four of seven participants (57%) whereas prescribed automatic stimulations were met in only two of seven participants (29%). Three participants (43%) had a modest benefit on DOSS. The time to vestibule closure after the bolus passed the ramus was reduced in five participants (71%) on the modified barium swallow study. CONCLUSION: Overall, the results have indicated that intensive home-based practice with stimulation may provide limited functional benefits in severe chronic dysphagia. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.21498591.

Comparing amplitudes of transcranial direct current stimulation (tDCS) to the sensorimotor cortex during swallowing.

PURPOSE: Transcranial direct current stimulation (tDCS) can alter cortical excitability, making it a useful tool for promoting neuroplasticity in dysphagia rehabilitation. Clinical trials show functional improvements in swallowing following anodal tDCS despite varying dosing parameters and outcomes. The aim of the current study was to determine the most effective amplitude criterion (e.g., 0 mA [sham/control], 1 mA, 2 mA) of anodal tDCS for upregulating the swallowing sensorimotor cortex. METHOD: As a novel paradigm, tDCS, functional near-infrared spectroscopy (fNIRS), and surface electromyography (sEMG) were simultaneously administered while participants completed a swallowing task. This allowed for measurement of the cortical hemodynamic response and submental muscle contraction before, during, and after tDCS. At the conclusion of the study, participants were asked to rate their level of discomfort associated with tDCS using a visual analog scale. RESULTS: There was no significant difference in the hemodynamic response by time or amplitude. However, post-hoc analyses indicated that in the post-stimulation period, changes to the hemodynamic response in the left (stimulated) hemisphere were significantly different for the groups receiving 1 mA and 2 mA of tDCS compared to baseline. Participants receiving 1 mA of tDCS demonstrated reduced hemodynamic response. There was no significant difference in submental muscle contraction during or after tDCS regardless of amplitude. Anodal tDCS was well tolerated in healthy adults with no difference among participant discomfort scores across tDCS amplitude. CONCLUSIONS: During a swallowing task, healthy volunteers receiving 1 mA of anodal tDCS demonstrated a suppressed hemodynamic response during and after stimulation whereas those receiving 2 mA of anodal tDCS had an increase in the hemodynamic response. tDCS remains a promising tool in dysphagia rehabilitation, but dosing parameters require further clarification.

An Exploration of Lung Volume Effects on Swallowing in Chronic Obstructive Pulmonary Disease.

Purpose Chronic obstructive pulmonary disease (COPD) limits respiration, which may negatively impact airway safety during swallowing. It is unknown how differences in lung volume in COPD may alter swallowing physiology. This exploratory study aimed to determine how changes in lung volume impact swallow duration and coordination in persons with stable state COPD compared with older healthy volunteers (OHVs). Method Volunteers ≥ 45 years with COPD (VwCOPDs; n = 9) and OHVs (n = 10) were prospectively recruited. Group and within-participant differences were examined when swallowing at different respiratory volumes: resting expiratory level (REL), tidal volume (TV), and total lung capacity (TLC). Participants swallowed self-administered 20-ml water boluses by medicine cup. Noncued (NC) water swallows were followed by randomly ordered block swallowing trials at three lung volumes. Estimated lung volume (ELV) and respiratory-swallow patterning were quantified using spirometry and respiratory inductive plethysmography. Manometry measured pharyngeal swallow duration from onset of base of tongue pressure increase to offset of negative pressure in the pharyngoesophageal segment. Results During NC swallows, the VwCOPDs swallowed at lower lung volumes than OHVs (p = .011) and VwCOPDs tended to inspire after swallows more often than OHVs. Pharyngeal swallow duration did not differ between groups; however, swallow duration significantly decreased as the ELV increased in VwCOPDs (p = .003). During ELV manipulation, the COPD group inspired after swallowing more frequently at REL than at TLC (p = .001) and at TV (p = .002). In conclusion, increasing respiratory lung volume in COPD should improve safety by reducing the frequency of inspiration after a swallow.

A Randomized Controlled Trial Comparing Physical and Mental Lingual Exercise for Healthy Older Adults.

Mental practice using motor imagery (MP-MI) has been shown to improve motor outcomes of upper and lower extremities especially when combined with physical exercise. Here, we studied community-dwelling, healthy older adults to determine the effects of including an MP-MI component with lingual strengthening exercise. In this pilot study, twenty-nine typically aging participants were assigned to an intervention group: physical lingual exercise (n = 7), physical and MP-MI lingual exercise (n = 8), MPMI lingual exercise (n = 7), or a control group (placebo exercise) (n = 7). All participants completed the assigned exercise regimen with three sessions per day, three days a week, for 6 consecutive weeks. Maximum isometric pressure (MIP) and regular effort saliva swallowing (RESS) pressure were collected at baseline and weeks 2, 4, and 6. A post hoc Bonferroni corrected treatment effect from baseline to week 6 was shown for only participants in the MP-MI/Physical exercise group for MIP (p = 0.003 MPMI/ Physical group; p = 0.11 Control group; p = 0.32 Physical only group; p = 0.14 MP-MI only group) and RESS (p = 0.009 MP-MI/Physical group; p = 0.14 Control group; p = 0.10 Physical only group; p = 0.04 MP-MI only group). Findings also indicate spontaneous carryover of significantly increased swallowing pressure when mental and physical exercise are combined. In conclusion, the potential effect of including an MPMI lingual exercise component in preventative and rehabilitative frameworks with older persons to possibly enhance functional swallowing improvement is promising and should be investigated.

Impaired Movement Scaling and Reduced Synchrony with Vestibule Closure Characterize Swallowing in Severe Dysphagia.

The contribution of hyoid and laryngeal movement deficits to penetration or aspiration in dysphagia is unclear, partly due to large variations in normal hyolaryngeal kinematics for swallowing. In healthy volunteers, laryngeal and hyoid kinematics relate to the requirements for laryngeal vestibule closure suggesting a central schematic control of movement magnitude and patterning for airway protection. Our first aim was to determine if patients with severe dysphagia showed evidence of an impaired swallowing schema, by examining if their kinematic measures were related to their hyolaryngeal space before swallow onset, and if hyolaryngeal movement synchrony for vestibule closure was disrupted. Our second aim was to determine the kinematic measures that predicted bolus penetration and aspiration in dysphagia. The methods included two-dimensional measures of the hyoid and laryngeal anterior and superior displacement and velocity, and the change in laryngeal vestibule area made from videofluoroscopic swallow recordings of 21 healthy volunteers and 21 patients with dysphagia on tube feeding secondary to the stroke or head and neck cancer. The results demonstrated that the patients did not adapt their hyolaryngeal movements during swallowing to their initial hyolaryngeal space. Further, none of the patients' measures of hyoid or laryngeal peak velocity timing were synchronized with vestibule closure, demonstrating a disorganized movement patterning. Laryngeal elevation peak velocity independently predicted penetration and aspiration. In conclusion, the central schema for swallowing patterning was disturbed, impairing the integration of kinematic actions for airway protection in severe dysphagia, while laryngeal peak elevation velocity predicted penetration and aspiration on patient swallows.

Laryngeal Vibration Increases Spontaneous Swallowing Rates in Chronic Oropharyngeal Dysphagia: A Proof-of-Principle Pilot Study.

Previously, vibratory stimulation increased spontaneous swallowing rates in healthy volunteers indicating that sensory stimulation excited the neural control of swallowing. Here, we studied patients with severe chronic dysphagia following brain injury or radiation for head and neck cancer to determine if sensory stimulation could excite an impaired swallowing system. We examined (1) if laryngeal vibratory stimulation increased spontaneous swallowing rates over sham (no stimulation); (2) the optimal rate of vibration, device contact pressure, and vibratory mode for increasing swallowing rates; and (3) if vibration altered participants' urge to swallow, neck comfort, and swallow initiation latency. Vibration was applied to the skin overlying the thyroid lamina bilaterally in thirteen participants to compare vibratory rates 30, 70, 110, 150, or 70 + 110 Hz, different devices to neck pressures (2, 4, or 6 kilopascals), and pulsed versus continuous vibration. Swallows were confirmed from recordings of laryngeal accelerometry and respiratory apneas and viewing neck movement. Participants' swallowing rates, urge to swallow, discomfort levels, and swallow initiation latencies were measured. Vibration at 70 Hz and at 110 Hz significantly increased swallowing rates over sham. All vibratory frequencies except 70 + 100 Hz increased participants' urge to swallow, while no pressures or modes were optimal for increasing urge to swallow. No conditions increased discomfort. Vibration did not reduce measures of swallow initiation latency using accelerometry. In conclusion, as non-invasive neck vibration overlying the larynx increased swallowing rates and the urge to swallow without discomfort in patients with chronic dysphagia, the potential for vibratory stimulation facilitating swallowing during dysphagia rehabilitation should be investigated.

Timing of cortical activation during spontaneous swallowing.

Saliva accumulation in the oropharynx generates an automatic pattern of swallowing in the brainstem in animals. Previous fMRI studies have found that spontaneous saliva and water swallows in humans evoked activation following swallow onset in both precentral motor and postcentral somatosensory cortical regions. Using event-related averaging of continuous functional near infrared spectroscopy (fNIRS), we examined cortical hemodynamic responses (HDR) from 5 s before to 35 s after spontaneous reflexive saliva swallow onset in the lateral postcentral somatosensory and precentral motor regions in both hemispheres in healthy volunteers. Three HDR changes from baseline were detected. First, the onset of HDR occurred 2 s before swallow onset in the left postcentral somatosensory area and 0.67 s before swallow onset in the right postcentral somatosensory area. Second, an early HDR peak amplitude occurred 3-4 s after swallow onset in all four regions. Z scores relative to baseline pre-swallow cortical activity levels averaged 20 and 22.7 s in the right and left somatosensory regions and 10 and 15.8 s in left and right motor areas, respectively. Finally, a late HDR peak occurring between 22 and 23 s after swallow onset in the somatosensory regions and 17-19 s in the motor areas likely resulted from esophageal peristalsis. Overall, cortical activation timing relative to swallow onsets showed activation began before the pharyngeal phase of swallowing in the somatosensory areas. This indicates that somatosensory triggering of swallowing occurs not only in the brainstem but also in the cortex for reflexive saliva swallowing in awake humans.

Sour taste increases swallowing and prolongs hemodynamic responses in the cortical swallowing network.

Sour stimuli have been shown to upregulate swallowing in patients and in healthy volunteers. However, such changes may be dependent on taste-induced increases in salivary flow. Other mechanisms include genetic taster status (Bartoshuk LM, Duffy VB, Green BG, Hoffman HJ, Ko CW, Lucchina LA, Weiffenbach JM. Physiol Behav 82: 109-114, 2004) and differences between sour and other tastes. We investigated the effects of taste on swallowing frequency and cortical activation in the swallowing network and whether taster status affected responses. Three-milliliter boluses of sour, sour with slow infusion, sweet, water, and water with infusion were compared on swallowing frequency and hemodynamic responses. The sour conditions increased swallowing frequency, whereas sweet and water did not. Changes in cortical oxygenated hemoglobin (hemodynamic responses) measured by functional near-infrared spectroscopy were averaged over 30 trials for each condition per participant in the right and left motor cortex, S1 and supplementary motor area for 30 s following bolus onset. Motion artifact in the hemodynamic response occurred 0-2 s after bolus onset, when the majority of swallows occurred. The peak hemodynamic response 2-7 s after bolus onset did not differ by taste, hemisphere, or cortical location. The mean hemodynamic response 17-22 s after bolus onset was highest in the motor regions of both hemispheres, and greater in the sour and infusion condition than in the water condition. Genetic taster status did not alter changes in swallowing frequency or hemodynamic response. As sour taste significantly increased swallowing and cortical activation equally with and without slow infusion, increases in the cortical swallowing were due to sour taste.

Role of cerebellum in deglutition and deglutition disorders.

The objective of this review is to gather available evidence regarding the role of the cerebellum in swallowing-related functions. We reviewed literature on cerebellar functions related to healthy swallowing, patterns of dysphagia in individuals with cerebellar lesions, and the role of the cerebellum in therapeutic intervention of neurogenic dysphagia since 1980. A collective understanding of these studies suggests that both hemispheres of the cerebellum, predominantly the left, participate in healthy swallowing. Also, it appears that the cerebellum contributes to specific physiological functions within the entire act of swallowing, but this is not clearly understood. The understanding of patterns of dysphagia in cerebellar lesions remains ambiguous with equivocal results across a small number of studies. The cerebellum appears to be involved in oral exercises for dysphagia in the relationship between oral movements in such exercises, and deglutition remains uncertain. There is increasing evidence to suggest successful use of transcranial magnetic stimulation of the cerebellum to improve neuromotor control of swallowing. Future studies should address activation of the cerebellum with swallowing of different consistencies and tastes in healthy adults to gain better insights. Studies should also investigate dynamics of neural activation during different stages of recovery from dysphagia following strokes to cortical centers to determine if the cerebellum plays a compensatory role during instances of increased neural demands.

Effects of topical nasal anesthetic on fiberoptic endoscopic examination of swallowing with sensory testing (FEESST).

Objections to the use of topical nasal anesthesia (TNA) during fiberoptic endoscopic evaluation of swallowing (FEES) with sensory testing (FEESST) have been raised, primarily because of the possibility of desensitizing the pharyngeal and laryngeal mucosa and affecting both the sensory and motor aspects of the swallow. Furthermore, it has been suggested that TNA is not necessary during FEES as it does not improve patient comfort or make the procedure easier for the endoscopist. The purpose of this double-blind, randomized, controlled, crossover clinical trial was to determine how gel TNA during flexible endoscopic evaluation of swallowing with sensory testing affects sensation, swallowing, and comfort rating scores in healthy non-dysphagic participants. Laryngopharyngeal sensory thresholds and swallowing durations were compared between two conditions: TNA and sham. Transition duration decreased statistically significantly during the TNA condition compared to the sham for 10 ml only (p < 0.05). All other swallowing measures did not change between the conditions. Laryngopharyngeal sensory thresholds and perceptions did not change between conditions. No change was observed for subject comfort scores, ease of exam, or quality of view. Future studies should evaluate TNA administration variables, including concentration, dosage amount, and method of application, to determine the optimal strategy for providing comfort while avoiding altered swallowing.

Effects of Mendelsohn maneuver on measures of swallowing duration post stroke.

PURPOSE: The purpose of this pilot study was to determine whether intensive use of the Mendelsohn maneuver in patients post stroke could alter swallow physiology when used as a rehabilitative exercise. METHOD: Eighteen outpatients between 6 weeks and 22 months post stroke were enrolled in this prospective study using a crossover design to compare 2 weeks of treatment with 2 weeks of no treatment. Each participant received an initial videofluoroscopic swallow study (VFSS) and an additional VFSS at the end of each week for 1 month for a total of 5 studies. During treatment weeks, participants received 2 treatment sessions per day performing Mendelsohn maneuvers with surface electromyography for biofeedback. Measures of swallowing duration, penetration/aspiration, residue, and dysphagia severity were analyzed from VFSS to compare treatment and no-treatment weeks. RESULTS: Significant changes occurred for measures of the duration of superior and anterior hyoid movement after 2 weeks of treatment. Improvements were observed for duration of opening of the upper esophageal sphincter (UES), but results were not statistically significant. Measures of penetration/aspiration, residue, and dysphagia severity improved throughout the study, but no differences were observed between treatment and no-treatment weeks. CONCLUSIONS: Intensive use of the Mendselsohn maneuver in isolation altered duration of hyoid movement and UES opening in this exploratory study. Results can guide future research toward improved selection criteria and exploration of outcomes. Larger numbers of participants and variations in treatment duration and intensity will be necessary to determine the true clinical value of this treatment.