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.

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.

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.

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.

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.

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.

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.

Effects of cortical anodal transcranial direct current stimulation on swallowing biomechanics.

BACKGROUND: Anodal transcranial direct current stimulation (tDCS) has demonstrated effects on corticobulbar excitability and swallowing function as assessed via clinical rating scales in stroke cohorts. Biomechanical effects of anodal tDCS on swallowing remain largely unexplored. We investigated how anodal tDCS applied over the floor of mouth (FOM) representation on the primary motor cortex affects swallowing biomechanics in healthy participants. METHODS: Anodal and sham tDCS were applied for 20 minutes at 1.5 mA. Corticobulbar excitability was assessed using motor evoked potentials at baseline and 0, 15, 30 and 45 minutes post-tDCS, as assessed by transcranial magnetic stimulation. Swallowing function was assessed pre- and post-tDCS using routine clinical assessments (Study 1) and pharyngeal high resolution impedance manometry (Study 2). KEY RESULTS: Study 1 (n = 17) showed increased corticobulbar excitability and performance on a skilled swallowing task following anodal wetDCS, but not sham tDCS. In Study 2 (n = 10) anodal tDCS resulted in increased bolus admittance across the upper esophageal sphincter, but decreased pharyngeal and upper esophageal contractile vigor. CONCLUSIONS: Clinical improvements of dietary intake are likely driven by swallowing neuroplastic reorganization which improves bolus admittance across the upper esophageal sphincter (UES). INFERENCES: The documented changes make motor cortical application of anodal tDCS a promising adjunct to swallowing rehabilitation practice.

Effectiveness of allied health therapy in the symptomatic management of progressive supranuclear palsy: a systematic review.

BACKGROUND: Progressive supranuclear palsy (PSP) is an adult onset neurodegenerative condition associated with mobility, balance, speech, swallowing, vision and cognitive changes. The condition is diagnosed using the National Institute for Neurological Disorders and Stroke (NINDS) and the Society of Progressive Supranuclear Palsy (SPSP) criteria. Therapeutic interventions for PSP are important, and a healthcare team should include a physiotherapist, occupational therapist and speech therapist. Mobility, speech and swallowing problems are commonly experienced, and aspiration pneumonia is the leading cause of death. A preliminary search of the literature has indicated that beyond small case series, there is very little evidence to guide specific allied health therapies in PSP. Many strategies for optimizing independence and function for PSP predominately rely on data extrapolated from the study of Parkinson's disease. OBJECTIVES: The objective of this review was to examine the effectiveness of physical, occupational and speech therapy interventions in the symptomatic management of PSP. INCLUSION CRITERIA TYPES OF PARTICIPANTS: This review included participants with PSP as per the NINDS and the SPSP criteria, aged over 40 years of age from all community and clinical settings. TYPES OF INTERVENTIONS: This review included studies evaluating any allied health therapy that addressed mobility, vision, swallowing, communication or cognitive/neuropsychiatric difficulties experienced by patients with PSP. Studies examining interventions within the current scope of practice, and emerging interventions (non-invasive brain stimulation therapy) were eligible for inclusion. TYPES OF COMPARATOR: The effectiveness of interventions of interest was compared with usual care and/or baseline measurements. OUTCOMES: Outcomes of interest included the degree of change, or no change, in the symptoms experienced by patients with PSP relevant to allied health. These included difficulties with mobility, vision, swallowing, communication and cognition. TYPES OF STUDIES: All types of quantitative study designs published in English from the time of development of the NINDS and the SPSP criteria in 1996-2014 were considered for inclusion. SEARCH STRATEGY: A broad range of synonyms for PSP and a three-step search strategy was utilized to identify possible published and unpublished studies from 11 different databases. An initial limited search via MEDLINE (PubMed), CINAHL, Health Informit, PsycINFO, PEDRO, OTSeeker and SpeechBite was undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. A second search using all identified keywords and index terms was then undertaken across all included databases. Third, hand-searching was conducted and the reference list of all identified reports and articles was searched for additional studies. METHODOLOGICAL QUALITY: Critical appraisal was conducted by two independent reviewers using standardized instruments. DATA EXTRACTION: Quantitative data were extracted from articles included in the review using standardized data extraction tools. DATA SYNTHESIS: As the quantitative articles examined different interventions, pooling of data was not appropriate. Instead, the findings were presented in narrative summary and tabular form. RESULTS: Following methodological appraisal, six studies were included in the review. Aside from one small quasi-randomized control study, most studies were small case series and one was a case report. Five of the six studies examined the effectiveness of a range of different physiotherapy rehabilitation programs targeting gait, balance and physical capability, with one study also targeting gaze control. The sixth study examined non-invasive brain stimulation in improving gait and midline symptoms in PSP. No studies examined the effectiveness of occupational therapy or speech therapy interventions in PSP. CONCLUSIONS: Research into the effectiveness of allied health therapeutic interventions for PSP symptoms is in its infancy. This review found preliminary evidence to support the use of various physiotherapy rehabilitation programs to improve balance, gait and gaze control in people affected by PSP. Further research is urgently required to identify effective interventions to manage mobility, vision, swallowing, communication and cognitive/neuropsychiatric symptoms associated with this devastating condition.

Behavioural and neurophysiological disruption of corticobulbar motor systems and their effects on sequential pharyngeal swallowing.

Primary motor networks are known to be involved in the control of voluntary oral movements as well as the modulation of pharyngeal movements during experimentally controlled single swallows performed on command. The role of these networks in the more typical task of sequential swallowing remains unexplored. This study evaluated the hypothesis that experimental disruption of motor cortical activation would reduce the rate and regularity of repeatedly performed volitional or volitionally initiated motor tasks controlled by corticospinal (finger tapping) and corticobulbar (eyebrow movement, jaw opening, volitional sequential swallowing) motor systems, but would not influence a more reflexive corticobulbar task (reflexive sequential swallowing to pharyngeal water infusion). This premise was investigated in 24 healthy participants using two techniques: a dual task paradigm and a transcranial magnetic stimulation paradigm. Disruption effects were quantified by changes in rate and regularity of performance for each tested motor task. In summary, volitional motor tasks controlled by corticospinal motor networks (finger tapping) are more susceptible to behavioural and neurophysiological disruption than tasks controlled by cortiobulbar motor networks containing a reflexive component (both volitional and experimentally initiated consecutive swallowing). Purely volitional motor tasks controlled by the corticobulbar motor system (eyebrow raising or jaw opening) were affected in similar ways as the volitional corticospinal motor tasks. In summary, tasks involving sequential pharyngeal swallowing - whether volitionally or experimentally initiated - are largely robust against disruption of primary cortical motor networks, supporting a key role of medullary CPGs in the motor control of sequential pharyngeal swallowing.

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.

A comparison of two methods for estimating 50% of the maximal motor evoked potential.

OBJECTIVES: Two commonly-used methods for setting stimulus intensities in transcranial magnetic brain stimulation studies were compared to determine which best approximated a motor evoked potential (MEP) of 50% of the maximal MEP amplitude (SI50); a suprathreshold intensity relative to resting motor threshold (rMT) or adjusting the intensity to evoke an MEP amplitude of 1mV. METHODS: Corticomotor stimulus-response curves and rMT for the right first dorsal interosseous (FDI) muscle of 176 subjects (aged 10-74 years) were retrospectively analysed. RESULTS: Regardless of subject age or sex, SI50 occurred at 127.5 ± 11.3% rMT. Except in young children, MEPs of 1 mV were significantly smaller than those evoked at SI50. CONCLUSIONS: In the inactive FDI muscle, a stimulus intensity of 127-128% rMT consistently gives the best approximation of SI50 in most subjects, except perhaps young children. SIGNIFICANCE: Setting TMS stimulus intensities relative to rMT provides a less variable inter-subject comparator, with respect to individual differences in corticomotor input-output characteristics, than adjusting the stimulator output to give an absolute MEP magnitude.

Transcranial non-invasive brain stimulation in swallowing rehabilitation following stroke--a review of the literature.

BACKGROUND: This descriptive review of the literature outlines the current evidence-base underpinning the potential of transcranial brain stimulation techniques to modulate swallowing function in healthy individuals and in treating post-stroke dysphagia. METHODS: Published research was identified by review of scientific databases (Scopus, Medline Ovid, Science Direct, AMED and Google Scholar) using relevant keywords. In addition, the reference lists of identified articles were scrutinized to identify further potentially relevant papers. Studies employing variants of transcranial magnetic or direct current stimulation for the purpose of modulating swallowing motor cortical excitability in healthy participants or dysphagia following stroke were included. Due to a significant heterogeneity in stimulation paradigms, all included studies were summarised and descriptively analysed in relation to the participants tested, cortical representations targeted by brain stimulation and outcome measures used. RESULTS: Seventeen studies met inclusion criteria (seven evaluating healthy participants, 10 evaluating participants presenting with post-stroke dysphagia). Cortical stimulation most commonly targeted pharyngeal motor representations (13/17 studies). In the 10 clinical studies, stimulation was applied contralesionally (5/10 studies), ipsilesionally (3/10 studies) or bilaterally (2/10 studies). A range of behavioural and neurophysiological outcome measures demonstrated positive effects on swallowing function across studies. CONCLUSION: There is promising proof of concept that non-invasive brain stimulation may provide a useful adjunct to post-stroke swallowing rehabilitation practice. Eventual transition of optimal paradigms into routine clinical practice will be accompanied by practical considerations in relation to local and national frameworks, e.g. the prescription and provision of treatment.

Pharyngeal pressure differences between four types of swallowing in healthy participants.

PURPOSE: The aim of this observational study was to identify biomechanical differences, as measured by pharyngeal manometric pressure patterns, between discrete and continuous water swallowing, as well as volitionally initiated and reflexive swallowing. METHODS: Using pharyngeal manometry, swallowing-related pressures from 24 young healthy individuals were recorded at three locations: upper pharynx, mid-pharynx and upper oesophageal sphincter (UES) during four swallowing conditions: discrete saliva swallowing, discrete 10ml water swallowing, volitional continuous water swallowing, and reflexive continuous water swallowing. Measures of peak pressure and pressure duration at each level were compared across conditions using repeated-measures analysis of variance. RESULTS: UES nadir pressure during saliva swallowing was lower than during water swallowing conditions (p<0.05). In addition, nadir pressure during discrete 10ml water swallowing was lower than during reflexive and volitional continuous water swallowing conditions (p<0.05). Saliva swallowing produced longer pressure duration than water swallowing conditions at the upper pharynx (p<0.05). Saliva swallowing produced pressure of greater duration than reflexive continuous water swallowing at mid-pharynx (p<0.05). Further, discrete 10ml water swallowing produced longer UES opening duration and longer pharyngeal pressure generation (p<0.05) than reflexive continuous water swallowing or saliva swallowing. CONCLUSION: Pressure generation differs between swallowing types and bolus types at the level of the UES in particular. These physiological differences between swallowing and bolus types may support clinical decisions for individuals with impaired swallowing.

Dysphagia Rehabilitation: Similarities and Differences in Three Areas of the World.

Although the goal of dysphagia rehabilitation is the same, population needs, clinical practice patterns, availability of resources, and dysphagia research varies greatly around the world. The goal of this review is to introduce the reader to the context in which dysphagia rehabilitation is practiced, to describe practice patterns, and to highlight the dysphagia research being performed in three distinct regions of the world: North America, New Zealand and Australia, and Japan.