Behavioral Interventions Targeting Base of Tongue to Posterior Pharyngeal Wall Approximation: A Scoping Review.

Pharyngeal pressure generated by approximation of the base of tongue to the posterior pharyngeal wall (BOT-PPW approximation) is critical for efficient pharyngeal bolus passage and is a frequent goal of dysphagia management. This scoping review evaluated behavioral interventions available to improve BOT-PPW approximation. We searched MEDLINE, CINAHL, Ovid Emcare, Web of Science, SCOPUS, and ProQuest for studies that met the following criteria: (i) behavioral interventions targeting BOT-PPW approximation, which (ii) were assessed using BOT-PPW-specific outcome measures, and (iiia) performed over a period of time (Review Part 1) or (iiib) studied immediate effects (Review Part 2). Study quality was rated using the GRADE framework. Data were extracted and synthesized into dominant themes. Of the 150 studies originally identified, three examined long-term effects (two single cases studies of individuals with dysphagia, and a third study evaluating effortful swallowing in healthy individuals). BOT-PPW approximation only increased in the two single case studies. Twenty-one studies evaluating immediate effects were categorized as follows: (1) effortful swallowing, (2) Mendelsohn maneuver, (3) tongue-hold maneuver, (4) super supraglottic swallowing maneuver, and (5) non-swallowing exercises. Across all studies, varying levels of success in increasing BOT-PPW approximation were reported. Four of 21 immediate effects studies evaluated patients with demonstrated swallowing impairment, whereas 17 studies evaluated healthy adults. Quality assessment revealed low strength of the existing evidence base. The evidence base for rehabilitative interventions targeting BOT-PPW approximation is severely limited and translation is hindered by small sample sizes and methodological limitations. Further clinical research is warranted.

Behavioral Interventions Targeting Insufficient Upper Esophageal Sphincter Opening During Swallowing: A Scoping Review.

The upper esophageal sphincter (UES) plays a central role in safe swallowing. Impaired UES opening is commonly observed in individuals presenting with impaired swallowing and various interventions are available aiming to improve bolus passage across the UES during swallowing. This scoping review addressed the following question: Which behavioral interventions are available to improve UES opening for deglutition? We searched MEDLINE, CINAHL, Ovid Emcare, Web of Science, SCOPUS and ProQuest for studies that met the following criteria: i. behavioral interventions targeting UES opening ii. performed over a period of time, which iii. were assessed using UES specific outcome measures. Study quality was assessed using the Joanna Briggs Institute and GRADE frameworks. Data were extracted and synthesized into dominant themes. Of the 357 studies originally identified, 15 met inclusion criteria and reported interventions that were grouped into four intervention types: (1) floor of mouth exercises that were sub-categorized into the Shaker exercise and other strengthening exercises, (2) Mendelsohn maneuver, (3) lingual exercises and (4) mixed exercise paradigms. Across the included studies, varying levels of success in improving various aspects of UES opening metrics were reported. Nine of 15 studies evaluated patients with demonstrated swallowing impairment, whereas six studies evaluated healthy adults. Quality assessment revealed significant variability in study quality, unclear reporting of participant training and treatment fidelity, as well as training dosage. The evidence base for the four behavioral intervention approaches targeting deglutitive UES opening is limited. The translation of existing evidence to clinical practice is hindered by small sample sizes and methodological limitations. Further research in this space is warranted.

Clinical reasoning and hypothesis generation in expert clinical swallowing examinations.

BACKGROUND: A clinical swallow examination (CSE) provides integral information that informs the diagnostic decision-making process within dysphagia management. However, multiple studies have highlighted a high degree of reported variability within the CSE process. It has been hypothesized that such variability may be the result of the clinical reasoning process rather than poor practices. AIMS: To elucidate the nature of expert, speech-language therapists' (SLTs) clinical reasoning during an initial bedside assessment of patients referred for suspected dysphagia in the acute care environment. METHODS & PROCEDURES: An exploratory 'observation of practice' qualitative methodology was used to achieve the aim. Four expert SLTs, from two clinical services, completed CSEs with 10 new referrals for suspected dysphagia. All assessments were video-recorded, and within 30 min of completing the CSE, a video-stimulated 'think aloud' semi-structured interview was conducted in which the SLT was prompted to articulate their clinical reasoning at each stage of the CSE. Three types of concept maps were generated based on this video and interview content: a descriptive concept map, a reasoning map and a hypothesis map. Patterns that consistently characterized the assessment process were identified, including the overall structure; types of reasoning (inductive versus deductive), facts (i.e., clinical information) drawn upon; and outcomes of the process (diagnosis and recommendations). Interview content was examined to identify types of expert reasoning strategies using during the CSE. OUTCOMES & RESULTS: SLTs' approach to clinical assessment followed a consistent structure, with data gathered pre-bedside, during the patient interview and direct assessment before a management recommendation was made. Within this structure, SLTs engaged in an iterative approach with inductive hypothesis-generating and deductive hypothesis-testing, with each decision-making pathway individually tailored and informed by patient-specific facts collected during the assessment. Clinical assessment was primarily geared towards management of an initial acute presentation with less focus on formulating a diagnostic statement. CONCLUSIONS & IMPLICATIONS: Variability in reported dysphagia practice is likely the result of a patient-centred assessment process characterized by iterative cycles of fact-gathering in order to generate and test clinical hypotheses. This has implications for the development of novel assessment tools, as well as professional development and education of novice SLTs. What this paper adds What is already known on the subject CSE practices are reportedly variable, which has led to calls for more stringent, standardized assessment tools. Emerging evidence suggests that this variation is non-random, but may arise from clinical reasoning processes. What this paper adds to existing knowledge We directly observed expert SLTs conducting CSEs and identified patterns in practice that were consistent across all CSEs evaluated. These patterns were consistent in structure, whereas the content of the assessment items varied and was tailored to individual patient presentation. Overall, expert SLTs engaged in balanced cycles of inductive hypothesis generation and deductive hypothesis-testing, a hallmark of good clinical assessment and practice. What are the potential or actual clinical implications of this work? Ensuring quality CSE requires a more nuanced approach that considers the role of clinical reasoning in SLTs' decision-making and the potential unintended negative consequences of standardized assessment tools.

Variables Impacting the Time Taken to Wean Children From Enteral Tube Feeding to Oral Intake.

OBJECTIVES: This study investigated biological factors, which may influence the time taken for children to wean from enteral to oral intake. METHODS: Retrospective case-note audit of 62 tube-fed children (nasogastric or percutaneous endoscopic gastrostomy) aged 6 months to 8 years, participating in an intensive tube weaning program. Program design included family-focused mealtimes, child autonomy, and appetite stimulation. A regression model was developed, which shows the combination of variables with the most predictive power for time taken to wean. RESULTS: Data from 62 children who were highly dependent (minimum 93% of calories provided enterally) on tube feeding for an extended period of time (mean = 2.1 years) were analysed. Children's mean body mass index z score at time of weaning was -0.47 (standard deviation 1.03) (mean weight = 10.54 kg) and 54 (87%) presented with a range of medical conditions. Forty-four children (71%) remained completely tube free at 3 months postintervention and an additional 5 children (10%) were fully tube weaned within 10 months of program commencement. Type of feeding tube, medical complexity, age, and length of time tube fed all significantly correlated with time taken to wean. Logistic regression modelling indicated that the type of feeding tube in combination with the degree of medical complexity and time tube fed were the strongest predictors of time taken to wean. CONCLUSIONS: Biological factors usually considered to impact on successful weaning from tube feeding (volume of oral intake, oral skill, or mealtime behaviours) were not relevant; however, the type of feeding tube in combination with the degree of medical complexity and time tube fed were the strongest predictors. The impact of psychosocial factors should be investigated to identify if these mitigated the effects of the biological variables.

Anodal Direct Current Stimulation of the Cerebellum Reduces Cerebellar Brain Inhibition but Does Not Influence Afferent Input from the Hand or Face in Healthy Adults.

BACKGROUND: The cerebellum controls descending motor commands by outputs to primary motor cortex (M1) and the brainstem in response to sensory feedback. The cerebellum may also modulate afferent input en route to M1 and the brainstem. OBJECTIVE: The objective of this study is to determine if anodal transcranial direct current stimulation (tDCS) to the cerebellum influences cerebellar brain inhibition (CBI), short afferent inhibition (SAI) and trigeminal reflexes (TRs) in healthy adults. METHODS: Data from two studies evaluating effects of cerebellar anodal and sham tDCS are presented. The first study used a twin coil transcranial magnetic stimulation (TMS) protocol to investigate CBI and combined TMS and cutaneous stimulation of the digit to assess SAI. The second study evaluated effects on trigemino-cervical and trigemino-masseter reflexes using peripheral nerve stimulation of the face. RESULTS: Fourteen right-handed healthy adults participated in experiment 1. CBI was observed at baseline and was reduced by anodal cerebellar DCS only (P < 0.01). There was SAI at interstimulus intervals of 25 and 30 ms at baseline (both P < 0.0001), but cerebellar tDCS had no effect. Thirteen right-handed healthy adults participated in experiment 2. Inhibitory reflexes were evoked in the ipsilateral masseter and sternocleidomastoid muscles. There was no effect of cerebellar DCS on either reflex. CONCLUSIONS: Anodal DCS reduced CBI but did not change SAI or TRs in healthy adults. These results require confirmation in individuals with neurological impairment.

Physiological evidence consistent with reduced neuroplasticity in human adolescents born preterm.

Preterm-born children commonly experience motor, cognitive, and learning difficulties that may be accompanied by altered brain microstructure, connectivity, and neurochemistry. However, the mechanisms linking the altered neurophysiology with the behavioral outcomes are unknown. Here we provide the first physiological evidence that human adolescents born preterm at or before 37 weeks of completed gestation have a significantly reduced capacity for cortical neuroplasticity, the key overall mechanism underlying learning and memory. We examined motor cortex neuroplasticity in three groups of adolescents who were born after gestations of ≤32 completed weeks (early preterm), 33-37 weeks (late preterm), and 38-41 weeks (term) using a noninvasive transcranial magnetic brain stimulation technique to induce long-term depression (LTD)-like neuroplasticity. Compared with term-born adolescents, both early and late preterm adolescents had reduced LTD-like neuroplasticity in response to brain stimulation that was also associated with low salivary cortisol levels. We also compared neuroplasticity in term-born adolescents with that in term-born young adults, finding that the motor cortex retains a relatively enhanced neuroplastic capacity in adolescence. These findings provide a possible mechanistic link between the altered brain physiology of preterm birth and the subsequent associated behavioral deficits, particularly in learning and memory. They also suggest that altered hypothalamic-pituitary-adrenal axis function due to preterm birth may be a significant modulator of this altered neuroplasticity. This latter finding may offer options in the development of possible therapeutic interventions.

Simultaneous application of slow-oscillation transcranial direct current stimulation and theta burst stimulation prolongs continuous theta burst stimulation-induced suppression of corticomotor excitability in humans.

The objective of this study was to assess whether the simultaneous application of slow-oscillation transcranial direct current stimulation enhances the neuroplastic response to transcranial magnetic theta burst stimulation. Motor evoked potential amplitude was assessed at baseline and at regular intervals up to 60 min following continuous theta burst stimulation, slow-oscillation transcranial direct current stimulation, and the simultaneous application of these paradigms. In addition, the electroencephalographic power spectra of slow and fast delta, and theta frequency bands recorded over the motor cortex were analyzed prior to and up to 5 min following each intervention. There was longer-lasting motor evoked potential suppression following the simultaneous application of continuous theta burst stimulation and slow-oscillation transcranial direct current stimulation compared with when continuous theta burst stimulation was applied alone. Slow-oscillation transcranial direct current stimulation applied alone did not modulate the motor evoked potential amplitude. No significant changes in spectral power were observed following slow-oscillation transcranial direct current stimulation. Simultaneous application of continuous theta burst stimulation and slow-oscillation transcranial direct current stimulation may provide an approach to prolong the induction of neuroplastic changes in motor cortical circuits by repetitive transcranial magnetic brain stimulation.

Swallowing neurorehabilitation: from the research laboratory to routine clinical application.

The recent application of neurostimulation techniques to enhance the understanding of swallowing neural plasticity has expanded the focus of rehabilitation research from manipulation of swallowing biomechanics to manipulation of underlying neural systems. Neuromodulatory strategies that promote the brain's ability to reorganize its neural connections have been shown to hold promising potential to aid the recovery of impaired swallowing function. These techniques include those applied to the brain through the intact skull, such as transcranial magnetic stimulation or transcranial direct current stimulation, or those applied to the sensorimotor system in the periphery, such as neuromuscular electrical stimulation. Recent research has demonstrated that each of these techniques, either by themselves or in combination with these and other treatments, can, under certain circumstances, modify the excitability of motor representations of muscles involved in swallowing. In some studies, experimentally induced plastic changes have been shown to have functional relevance for swallowing biomechanics. However, the transition of novel, neuromodulatory brain stimulation techniques from the research laboratory to routine clinical practice is accompanied by a number of ethical, organizational, and clinical implications that impact professions concerned with the treatment of swallowing rehabilitation. In this article, we provide a brief overview of the neuromodulatory strategies that may hold potential to aid the recovery of swallowing function, and raise a number of issues that we believe the clinical professions involved in the rehabilitation of swallowing disorders must confront as these novel brain stimulation techniques emerge into clinical practice.

Effects of submental neuromuscular electrical stimulation on pharyngeal pressure generation.

OBJECTIVE: To investigate the immediate and late effects of submental event-related neuromuscular electrical stimulation (NMES) on pharyngeal pressure generation during noneffortful and effortful saliva swallows. DESIGN: Before-after trial. SETTING: Swallowing rehabilitation research laboratory. PARTICIPANTS: Sex-matched (N=20) healthy research volunteers. INTERVENTIONS: Participants received 80Hz NMES of 4-second duration to floor of mouth muscles that was time-locked to 60 volitional saliva swallows. MAIN OUTCOME MEASURES: Manometry measures of peak pressures and duration of pressure events in the oropharynx, hypopharynx, and the upper esophageal sphincter (UES) were derived during execution of noneffortful and effortful saliva swallows. Measures were taken at baseline, during stimulation, and at 5-, 30-, and 60-minutes poststimulation. RESULTS: Baseline pharyngeal and UES pressures did not differ between stimulated and nonstimulated swallows. At 5- and 30-minutes poststimulation, peak pressure decreased at the hypopharyngeal and at the UES sensor during noneffortful swallows. The effect lasted up to an hour only in the hypopharynx. No changes in duration of pressure events were observed. CONCLUSIONS: Using this treatment paradigm, decreased peak amplitude in the hypopharynx up to an hour after treatment indicates a potential risk of decreased bolus flow associated with NMES. On the other hand, decreased UES relaxation pressure may facilitate bolus transit into the esophagus.

Intra- and inter-rater reliability for analysis of hyoid displacement measured with sonography.

PURPOSE: Anterior hyoid displacement is essential for efficient swallowing and is usually investigated with videofluoroscopy. Ultrasound offers a less expensive and noninvasive method of investigation. The present study investigated the viability of a novel method of quantifying hyoid displacement from sonograms using an anatomic reference point, through an evaluation of inter- and intra-rater reliability. METHODS: Three raters reviewed the sonographic video sweeps of five discrete swallows from each of five participants for inter-rater reliability. The primary investigator measured each swallow on two occasions for intra-rater reliability. Electronic calipers were used to measure distances from a "rest" frame prior to the swallow of interest and a "maximal displacement" frame, at which the hyoid bone was at maximal anterior displacement during each swallow. RESULTS: Single-measure intraclass correlation coefficient was high for inter-rater agreement at 0.86 for rest measures and 0.86 for maximal displacement. Intra-rater reliability was even higher at 0.95 for rest and 0.98 for maximal displacement. CONCLUSIONS: These preliminary results suggest that by using a novel analysis approach involving an anatomic reference point, raters can achieve high agreement on measurement of position of hyoid at maximal displacement relative to rest.

The prevalence of post-extubation dysphagia in critically ill adults: an Australian data linkage study.

Objective: To define the prevalence of dysphagia after endotracheal intubation in critically ill adult patients. Design: A retrospective observational data linkage cohort study using the Australian and New Zealand Intensive Care Society Adult Patient Database and a mandatory government statewide health care administration database. Setting: Private and public intensive care units (ICUs) within Victoria, Australia. Participants: Adult patients who required endotracheal intubation for the purpose of mechanical ventilation within a Victorian ICU between July 2013 and June 2018. Main outcome measures: Presence of dysphagia, aspiration pneumonia, ICU length of stay, hospital length of stay, and cost per episode of care. Results: Endotracheal intubation in the ICU was required for 71 124 patient episodes across the study period. Dysphagia was coded in 7.3% (n = 5203) of those episodes. Patients with dysphagia required longer ICU (median, 154 [interquartile range (IQR), 78-259] v 53 [IQR, 27-107] hours; P < 0.001) and hospital admissions (median, 20 [IQR, 13-30] v 8 [IQR, 5-15] days; P < 0.001), were more likely to develop aspiration pneumonia (17.2% v 5.6%; odds ratio, 3.0; 95% CI, 2.8-3.2; P < 0.001), and the median health care expenditure increased by 93% per episode of care ($73 586 v $38 108; P < 0.001) compared with patients without dysphagia. Conclusions: Post-extubation dysphagia is associated with adverse patient and health care outcomes. Consideration should be given to strategies that support early identification of patients with dysphagia in the ICU to determine if these adverse outcomes can be reduced.

Swallowing biomechanics before and following multi-level upper airway surgery for obstructive sleep apnea.

STUDY OBJECTIVES: The effect of contemporary multi-level upper airway surgery for obstructive sleep apnea on swallowing is unclear. This study assessed the biomechanical swallowing function in participants with obstructive sleep apnea pre- and post-modified uvulopalatopharyngoplasty and coblation channeling of the tongue. METHODS: In this prospective, longitudinal study, adults diagnosed with moderate-severe obstructive sleep apnea who underwent modified uvulopalatopharyngoplasty and coblation channeling of the tongue surgery had swallowing biomechanics assessed using high-resolution pharyngeal manometry and analyzed with swallowgateway.com. Symptomatic swallowing difficulty was evaluated using the Sydney Swallow Questionnaire (≥ 234). General linear mixed-model analysis was conducted to evaluate the difference pre- and post-modified uvulopalatopharyngoplasty and coblation channeling of the tongue. Data are presented as mean [95% confidence intervals]. RESULTS: High-resolution pharyngeal manometry assessments were conducted in 10 participants (7 men; median age 50 [interquartile range 36-65]) preoperatively and repeated postoperatively at 9 months [interquartile range 6-13]. Self-reported dysphagia was unchanged following surgery (Sydney Swallow Questionnaire =149 [53, 447] to 168 [54, 247]; P = .093). High-resolution pharyngeal manometry outcomes indicated reduced mesopharyngeal pressures (148 [135, 161] to 124 [112, 137] mm Hg s cm; P = .011), reduced hypopharyngeal pressures (113 [101, 125] to 93 [84, 102] mm Hg s cm; P = 0.011), and reduced upper esophageal sphincter relaxation pressure (5 [4, 6] to 2 [1,3] mm Hg; P = 0.001) but no change to velopharyngeal pressures (135 [123, 147] to 137 [117, 157] mm Hg s cm; P = .850) postsurgery. CONCLUSIONS: Modified uvulopalatopharyngoplasty may have less implications on the swallow mechanism than previously suspected. In contrast, the reduction in mesopharyngeal contractile pressures associated with coblation channeling of the tongue, although within normal limits, may affect bolus propulsion. Biomechanical alterations were insufficient to worsen self-reported swallowing function. CITATION: Schar MS, Omari TI, Woods CW, et al. Swallowing biomechanics before and following multi-level upper airway surgery for obstructive sleep apnea. J Clin Sleep Med. 2022;18(4):1167-1176.

Modulation of cortical motor networks following primed θ burst transcranial magnetic stimulation.

To investigate whether priming stimulation influences the responses of intracortical inhibitory and facilitatory motor circuits to a subsequent plasticity-inducing inhibitory theta burst TMS paradigm. Using standard transcranial magnetic stimulation (TMS) procedures, MEP amplitude, short-interval intracortical inhibition (SICI), and short-interval intracortical facilitation (SICF) were assessed at baseline and 5, 20 and 30 min following continuous theta burst stimulation (cTBS), intermittent TBS (iTBS), and iTBS-primed cTBS. SICI was assessed using paired-pulse TMS at inter-stimulus intervals (ISI) of 3 ms (SICI(3)) and the latency corresponding to the latency at which SICF was minimal in each individual. SICF was assessed at ISIs corresponding to Peak 1, Trough 1, Peak 2, and Peak 3 of each individual's SICF curve. When applied alone cTBS inhibited and iTBS facilitated MEP amplitudes. iTBS-primed cTBS resulted in greater MEP inhibition than cTBS alone. There were no changes in SICF and only marginal changes in SICI following any intervention. Synapses mediating MEP generation undergo modification following iTBS-primed cTBS, possibly through mechanisms related to metaplasticity or synaptic depotentiation. A lack of substantial changes in SICI and SICF under all experimental conditions suggests that the tested rTMS paradigms may be non-optimal for inducing robust modulation of the neural elements mediating SICI and SICF across subjects. Priming stimulation may provide an approach which facilitate neuroplastic change within the human motor cortex at least in circuits responsible for MEP generation.

Effects of repeated volitional swallowing on the excitability of submental corticobulbar motor pathways.

The aim of this study was to examine the effects of repeated volitional saliva swallowing on corticobulbar excitability recorded during two muscle preactivation conditions of the submental muscle group. Motor-evoked potentials (MEPs), elicited by transcranial magnetic stimulation (TMS), were assessed in ten healthy volunteers prior to and at 5, 30, 60, and 90 min after 60 volitional saliva swallows (Protocol A). To control for intrinsic fluctuations in corticobulbar excitability during this assessment period, MEPs were also recorded, on a different day, at 30-min intervals across a 2-h period (Protocol B). At each assessment, 15 MEPs were recorded during two submental muscle preactivation conditions: volitional contraction and contraction associated with the pharyngeal phase of volitional swallowing. There were no significant effects of repetitive volitional swallowing or time on MEP measures (p>0.05). We conclude that volitional saliva swallowing does not have immediate effects on the excitability of corticobulbar projections to the submental musculature during volitionally initiated swallowing motor tasks. These results provide no evidence for use-dependent potentiation of corticobulbar excitability through repetitive saliva swallowing. The lack of effects of time on mean MEP measures supports previous reports of good intrasession reliability of MEPs as a measure of corticobulbar excitability.

Characterizing International Approaches to Weaning Children From Tube Feeding: A Scoping Review.

Approaches to tube weaning enterally fed children and evaluating outcomes vary widely. This limits the utility of research for identifying both "what works" and successful implementation of research outcomes. We used a qualitative scoping review methodology to examine internationally published research. Our primary aim was to identify the main philosophies underpinning intervention design and the main outcome variables used to demonstrate success of existing programs. This information can be used to inform future research design and clinical practice. Literature up until June 2019 was sourced via Medline, Scopus, Ovid, and CINHAL databases; hand searching; and gray literature using Google Advanced Search. Three predominant approaches to tube-weaning interventions were identified: behavioral, child- and family-centered, and biomedical. A wide range of intervention variables were identified, with the level of parental involvement and the use of hunger provocation varying between approaches. Our Review also confirms that there is no consistency in outcome measures used, limiting comparability between programs. We suggest that the role of parents in the weaning process and its impact on both the child and the parent/carer while transitioning from enteral to oral eating are insufficiently understood. We discuss these findings in the context of a suggested framework for future research.

Videofluoroscopic and manometric outcomes of cricopharyngeus balloon dilation for treatment of pharyngo-esophageal dysphagia associated with nasopharyngeal cancer: A case series.

BACKGROUND: Problems with pharyngo-esophageal bolus flow have been reported following nasopharyngeal cancer (NPC) treatment. While studies using videofluoroscopic assessment have shown balloon dilation can help address this impairment, the impact of dilation on pressure and bolus flow characteristics incorporating high-resolution pharyngeal manometry (HRPM) has not been reported. METHODS: Five cases with pharyngo-esophageal dysphagia post NPC underwent balloon dilation. Videofluoroscopic swallowing study (VFSS) and HRPM were completed before and 1 month post dilation. Oral intake and dysphagia related quality of life were reported to 3 months. RESULTS: VFSS, manometry and functional outcomes revealed positive benefits from dilation in two cases. In the other three cases, two showed improvements on VFSS only. These three failed to make functional swallowing gains. CONCLUSIONS: Where there was functional gain, both fluoroscopy and HRPM recorded improvement to UES function. Across the cases, response to dilation was variable and further work is needed to determine which patients would receive most benefit. LEVEL OF EVIDENCE: 4.

Biomechanical correlates of sequential drinking behavior in aging.

BACKGROUND: The timed water swallow test (TWST) is a test of sequential swallowing where a measured volume is ingested as quickly as comfortably possible. We undertook a study of the biomechanics underpinning the TWST in healthy young and older participants. METHODS: Thirty healthy volunteers underwent high-resolution impedance manometry (MMS; Unisensor, 2.7 mm diameter, 32 pressure sensors, 16 impedance segments). Participants were asked to drink 150 mL, 0.9% normal saline solution rapidly. Swallowing biomechanics and bolus flow characteristics were assessed using pressure-flow analysis and compared using t test and Fisher's exact test with significance as P < .05. KEY RESULTS: Older participants (n = 18; 76 ± 11 years) took longer to complete the TWST (21.2 ± 2.5 vs 9.2 ± 1.0 seconds; P < .001) and displayed reduced volume per swallow (16.6 ± 1.3 vs 27.8 ± 2.9 mL; P < .001) compared to younger participants (n = 12; 29 ± 5 years). Two distinctive pharyngeal swallowing patterns were observed: (a) a single rapid sequence of swallows with or without a clearing swallow (Pattern I) or (b) multiple, shorter sequences interrupted and/or interspersed with single swallows or breaks (Pattern II). Some older participants showed biomechanical evidence of upper esophageal sphincter restriction (n = 7) or impaired deglutitive inhibition (n = 7), associated with the more prolonged Pattern II (TWST duration 30.1 ± 1.5 vs Pattern I 11.9 ± 1.5 seconds; P < .001). CONCLUSIONS AND INFERENCES: Healthy older participants had an increased duration of TWST, suggesting a need to adapt normative values for this population. Rapid sequential swallowing was associated with evidence of UES restriction and impaired deglutitive inhibition in some older participants.

Altered swallowing biomechanics in people with moderate-severe obstructive sleep apnea.

STUDY OBJECTIVES: Dysphagia is a common but under-recognized complication of obstructive sleep apnea (OSA). However, the mechanisms remain poorly described. Accordingly, the aim of this study was to assess swallowing symptoms and use high-resolution pharyngeal manometry to quantify swallowing biomechanics in patients with moderate-severe OSA. METHODS: Nineteen adults (4 female; mean (range) age, 46 ± 26-68 years) with moderate-severe OSA underwent high-resolution pharyngeal manometry testing with 5-, 10-, and 20-mL volumes of thin and extremely thick liquids. Data were compared with 19 age- and sex-matched healthy controls (mean (range) age, 46 ± 27-68 years). Symptomatic dysphagia was assessed using the Sydney Swallow Questionnaire. Swallow metrics were analyzed using the online application swallowgateway.com. General linear mixed model analysis was performed to investigate potential differences between people with moderate-severe OSA and controls. Data presented are means [95% confidence intervals]. RESULTS: Twenty-six percent (5 of 19) of the OSA group but none of the controls reported symptomatic dysphagia (Sydney Swallow Questionnaire > 234). Compared with healthy controls, the OSA group had increased upper esophageal sphincter relaxation pressure (-2 [-1] vs 2 [1] mm Hg, F = 32.1, P < .0001), reduced upper esophageal sphincter opening (6 vs 5 mS, F = 23.6, P < .0001), and increased hypopharyngeal intrabolus pressure (2 [1] vs 7 [1] mm Hg, F = 19.0, P < .05). Additionally, upper pharyngeal pressures were higher, particularly at the velopharynx (88 [12] vs 144 [12] mm Hg⋅cm⋅s, F = 69.6, P < .0001). CONCLUSIONS: High-resolution pharyngeal manometry identified altered swallowing biomechanics in people with moderate-severe OSA, which is consistent with a subclinical presentation. Potential contributing mechanisms include upper esophageal sphincter dysfunction with associated upstream changes of increased hypopharyngeal distension pressure and velopharyngeal contractility. CITATION: Schar MS, Omari TI, Woods CM, et al. Altered swallowing biomechanics in people with moderate-severe obstructive sleep apnea. J Clin Sleep Med. 2021;17(9):1793-1803.

Test-retest reliability of motor evoked potentials (MEPs) at the submental muscle group during volitional swallowing.

Motor evoked potentials (MEPs) recorded from pharyngeal and anterior hyo-mandibular (submental) muscles at rest have been used to evaluate treatment effects on neural pathways underlying swallowing. This study documents a novel methodological approach of recording reliable intra- and inter-session MEPs at the submental muscle group during task-related volitional swallowing. MEPs were elicited by single-pulse transcranial magnetic stimulation (TMS), triggered by a custom-made system when a pre-set level of surface electromyographic activity in the target muscles was breached. Fifteen MEPs were recorded during each of four sessions. Intraclass correlation coefficients (ICCs) were used to assess test-retest reliability within and across sessions for blocks of 3, 5, 10 and 15 trials. Highly reliable intra-session reliability was achieved, maximal for blocks of five trials (0.915). Inter-session reliability varied between 0.474 (three trials per block) and 0.909 (10 trials per block). Surface electromyography-triggered TMS allows reliable measurement of MEP amplitude at the submental muscle group within and across sessions when muscles are pre-activated during volitional swallowing. This methodology will be useful for future investigations on the effects of pathology and modulation of swallowing neural pathways.