The effect of surface electrical stimulation on hyolaryngeal movement in normal individuals at rest and during swallowing

Factors Associated With Time to Decannulation in Patients With Tracheostomy Following Severe Traumatic Brain Injury

BACKGROUND

Prolonged tracheal tube placement following severe traumatic brain injury (TBI) can cause serious complications. Safe removal requires sufficient ability for independent breathing and airway protection. Thus, identifying important factors for time to removal of the tracheal tube (decannulation) is essential for safe and efficient weaning. This study aimed to identify significant factors for time to decannulation in a Danish population of subjects with tracheostomy after TBI.

METHODS

This was a retrospective register-based cohort study. Subjects with moderate and severe TBI and a tracheal tube were selected from the Danish Head Trauma Database between 2011-2021. Time to decannulation was calculated as time from injury to decannulation. Associations between selected explanatory variables representing demographic and clinical characteristics and time to decannulation were analyzed using linear regression models.

RESULTS

A total 324 subjects were included with a median of 44 d to decannulation. Primary analysis found that an improvement in swallowing ability during the initial 4 weeks of rehabilitation was associated with an 8.2 d reduction in time to decannulation (95% CI -12.3 to -4.2, P < .001). Change in overall sensorimotor ability reduced time to decannulation by 0.94 (95% CI -0.78 to -0.10, P = .03) d. Change in cognitive abilities from rehab admission to 4-week follow-up did not significantly affect the number of days to decannulation (P = .66). Secondary analysis showed pneumonia was associated with the largest estimated increase of 24.4 (95% CI 15.9-32.9, P < .001) d and that increased cognitive functioning at rehabilitation admission was associated with a significant reduction in time to decannulation.

CONCLUSIONS

This study found that a change in swallowing ability is a potentially significant factor for reducing time to decannulation. Identifying factors that could explain differences in time to decannulation is essential for patient outcomes, especially if these factors are modifiable and could be targeted in rehabilitation and treatment.

Radiographic Magnification on Videofluoroscopy: An Important Variable to Consider for Scaled Analyses of Swallowing

PURPOSE

Traditionally, kinematic measures on videofluoroscopy require the use of an external scalar (such as a penny) to transform pixels to absolute distances. Videofluoroscopy is subject to image magnification based on the distance of the feature of interest to the X-ray source. However, the impact of the position/location of the external scalar on swallowing measures is unknown. Our goal was to systematically investigate the accuracy of various common external scalar locations in lateral and anterior-posterior (A-P) view.

METHOD

U.S. pennies were taped to a styrofoam head in three positions (on the left and right lateral neck and in midline submentally). Locations were measured to ensure equal left and right, as well as midline, placement. A metal screwdriver (6 mm in diameter) was inserted into the premanufactured hole that is centrally located at the bottom of the styrofoam head. The head was centered on a medical tray and placed in the middle of a Siemens Alpha C-arm Fluoroscope field. ImageJ was used to measure penny length in pixels (three locations) in both lateral and A-P views. Penny length was known (19.05 mm), and, therefore, used to derive screwdriver size (for each location) for comparison to the actual screwdriver size.

RESULTS

All scalars overestimated the screwdriver size ranging from 6.55 to 7.87 mm, representing a 9%-31% inflation. Scalars closer to the X-ray source had the largest magnification.

CONCLUSIONS

Our results confirm that image magnification of external scalars is a significant source of variability that is currently unaccounted for in the swallowing literature. Recommendations for future research design/measurement methods are provided.

The Impact of Vocal Task on Voice Acoustics, Effort and Discomfort Following Submandibular Neuromuscular Electrical Stimulation in Healthy Adults

BACKGROUND

Neuromuscular electrical stimulation (NMES) offers a potential adjuvant to traditional voice therapy for individuals with dysphonia. The type of vocal task to implement in conjunction with electrical stimulation to achieve maximal therapeutic benefit is unknown. The purpose of this study was to elucidate the impact of tasks on voice outcomes.

METHODS

Nineteen vocally-healthy adult females, between 23 and 27 years of age (Ave: 23.8, SD: 1.13), participated in the study. 15 participants completed all three 30-minute sessions, and four completed at least one session. NMES was paired with three different voice conditions: high-pitched hum, low-pitched hum, and comfortable-pitched hum. Acoustic (average fundamental frequency and loudness; perturbation (jitter, shimmer, noise to harmonic ratio); Cepstral Spectral Index of Dysphonia; pitch range), perceived phonatory effort, and discomfort (delayed onset muscle soreness) measures were compared across conditions.

RESULTS

Eight participants experienced discomfort following NMES. Three participants withdrew from the study due to discomfort, and one withdrew due to an unrelated oral surgery. NMES paired with high-pitch humming resulted in increased average fundamental frequency during sustained phonation and reading tasks, and increased Cepstral Spectral Index of Dysphonia during sustained phonation. Low-pitch humming resulted in a decreased noise to harmonic ratio. No statistically significant changes in perceived phonatory effort were noted.

CONCLUSION

Almost half of the participants reported temporary discomfort. Task-specific differences in some outcomes were noted indicating that the nature of voice task performed with NMES must be considered when examining the impact of NMES on voice. Vocal tasks can impact discomfort and acoustic vocal outcomes of NMES.

Kinematic mechanism of the rehabilitative effect of 4-channel NMES: post-hoc analysis of a prospective randomized controlled study

The sequential 4-channel neuromuscular electrical stimulation (NMES), based on the normal contractile sequences of swallowing-related muscles, is a new rehabilitative treatment. The objective of this study was to explore the mechanism of the rehabilitative effect of the 4-channel NMES using kinematic analysis of videofluoroscopic swallowing study (VFSS) data. For this post-hoc analysis, we included a subset of participants from the prospective randomized controlled study on the clinical effectiveness of the sequential 4-channel NMES compared with that of the conventional 2-channel NMES. Seventeen subjects (11 and six in the 4- and 2-channel NMES groups, respectively) were eligible for the kinematic analysis of VFSS data. The hyoid bone movement was analyzed by evaluating the distance and time parameters with four peak points (A, B, C, D). The 4-channel NMES group showed significant improvement in vertical distances (A-C), horizontal distance (A-B, A-C), time interval (A-B-C) and total time, compared with their pretreatment data. The 2-channel NMES group showed significant improvements in time interval (A-B); however, the Euclidean distance (A-D) and mean velocity of the Euclidean distance (A-C) were significantly decreased. When the two groups were directly compared, the 4-channel group showed significantly greater improvement in horizontal distance (A-B), Euclidean distance (A-D), time interval (A-B-C), and mean velocity the Euclidean distance (A-D). The results in this study suggest that the sequential 4-channel NMES might lead to the physiologic circular movement of the hyoid bone during swallowing, and therefore be an effective treatment for dysphagia.Trial registration: Clinicaltrials.gov, registration number: NCT03670498.

Non-Contact Assessment of Swallowing Dysfunction Using Smartphone Captured Skin Displacements

Early and accurate dysphagia diagnosis is essential for reducing the risk of associated co-morbidities and mortalities. Barriers to current evaluation methods may alter the effectiveness of identifying at-risk patients. This preliminary study evaluates the feasibility of using iPhone X-captured videos of swallowing as a non-contact dysphagia screening tool. Video recordings of the anterior and lateral necks were captured simultaneously with videofluoroscopy in dysphagic patients. Videos were analyzed using an image registration algorithm (phase-based Savitzky-Golay gradient correlation (P-SG-GC)) to determine skin displacements over hyolaryngeal regions. Biomechanical swallowing parameters of hyolaryngeal displacement and velocity were also measured. Swallowing safety and efficiency were assessed by the Penetration Aspiration Scale (PAS), Residue Severity Ratings (RSR), and the Normalized Residue Ratio Scale (NRRS). Anterior hyoid excursion and horizontal skin displacements were strongly correlated with swallows of a 20 mL bolus (r_s = 0.67). Skin displacements of the neck were moderately to very strongly correlated with scores on the PAS (r_s = 0.80), NRRS (r_s = 0.41-0.62), and RSR (r_s = 0.33). This is the first study to utilize smartphone technology and image registration methods to produce skin displacements indicating post-swallow residual and penetration-aspiration. Enhancing screening methods provides a greater chance of detecting dysphagia, reducing the risk of negative health impacts.

Assessing Discomfort Levels During Facial Neuromuscular Electrical Stimulation Using Discomfort Level Scale: A Preliminary Study

The primary aim of the current study was to evaluate discomfort levels of facial NMES in healthy volunteers. Eight participants completed the Discomfort Level Scale (DLS) following each motor level facial neuromuscular electrical stimulation (NMES) session. Each participant completed 12 sessions of facial NMES for a total of 96 NMES treatments. Pearson product-moment correlation coefficient demonstrated a significant correlation between the facial NMES intensity level and DLS (p < 0.001). This study demonstrated that the DLS is a useful tool to check for discomfort levels in patients who receive facial NMES. Further, this study provides strong support for the tolerability of facial NMES.

Healthy Volunteers Immediately Adapt to Submental Stimulation During Swallowing

OBJECTIVES

Transcutaneous stimulation above and below the hyoid is used to assist patients with swallowing disorders (dysphagia) but has shown different effects. Previously, infrahyoid transcutaneous stimulation lowered the hyoid and larynx resisting swallowing movement while suprahyoid stimulation had no effects on hyolaryngeal movement either at rest or during swallowing. More recently, large submental electrodes, covering the submental region, are used for swallowing therapy in combination with resistance therapy. To gain insight into the effects of these electrodes on movement during swallowing, we studied healthy volunteers using videofluoroscopy (VF). We hypothesized that submental electrical stimulation might elevate the hyoid but not the larynx increasing vestibular opening potentially reducing swallowing safety.

MATERIALS AND METHODS

While undergoing VF, seven healthy volunteers (mean age 51, 5 males) swallowed 5 mL of liquid barium on at least ten trials randomly ordered across three conditions: stimulation at rest, swallowing without stimulation, and swallowing with stimulation.

RESULTS

During stimulation at rest, significant (one tailed p < 0.05) anterior movement occurred in the hyoid and larynx, no superior hyoid and laryngeal movement and an increase in the distance between the hyoid and larynx. When comparing swallowing with and without submental stimulation, during stimulation volunteers significantly reduced anterior hyoid motion (p = 0.028) and increased hyoid elevation (p = 0.043) without changing anterior or superior laryngeal movement or the distance between the hyoid and larynx.

CONCLUSIONS

The healthy volunteers immediately corrected for the effects of submental stimulation by reducing hyoid anterior motion and increasing superior hyoid motion without changing laryngeal motion to prevent increased vestibule opening with stimulation. This suggests that healthy volunteers had an internal schema for swallowing movement patterning with feedforward correction for the effects of stimulation.

Effect of Peripheral Magnetic Stimulation for Dysphagia Rehabilitation: A Systematic Review

Recently, a therapeutic method to stimulate the suprahyoid muscle using peripheral magnetic stimulation for dysphagia rehabilitation has been reported. However, clinical evidence, application protocol, and intervention method remain unclear. Therefore, a systematic review of the published literature is needed. The objective of this study was to systematically review clinical studies of peripheral magnetic stimulation applied for rehabilitation of dysphagia. Issues to be considered in future studies are also suggested. This systematic review performed a literature search of four databases (Medline, Embase, CINAHL, and Web of Science) to identify relevant studies published on the application of repetitive peripheral magnetic stimulation (rPMS) for swallowing-related muscles between 2010 and 2022. Seven studies were reviewed. Randomized controlled trials and one-group pre-post, case study designs were included. In the included studies, rPMS was applied to strengthen the submental suprahyoid muscles. The intervention regime varied. The rPMS was applied at a frequency of 30 Hz for 2 s. Rest time ranged from 8 s to 27-28 s. The number of intervention sessions ranged from 2-3 to 30. The intensity ranged from pain-inducing minimum intensity (90% of maximum stimulus output) to non-painful intensity (70-80% of maximum intensity). The rPMS on the suprahyoid muscles had positive effects on physiological changes in the swallowing function, such as displacement of the hyoid bone, muscle strength (cervical flexor, jaw-opening force), swallowing safety, swallowing performance, and swallowing-related quality of life. Participants also reported little pain and adverse reactions during rPMS. Although rPMS is a therapeutic option that can help improve the swallowing function as a non-invasive stimulation method in the rehabilitation of dysphagia, clinical evidence is needed for the development of clear stimulation protocols and guidelines.

Therapeutic Effect and Optimal Electrode Placement of Transcutaneous Neuromuscular Electrical Stimulation in Patients with Post-Stroke Dysphagia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: To date, there is no conclusive evidence that transcutaneous neuromuscular electrical stimulation (TNMES) benefits patients with post-stroke dysphagia (PSD). In addition, the optimal TNMES electrode placement has not been well-established. This systematic review and meta-analysis were conducted to investigate these two research gaps. Methods: Five major databases were systematically searched for randomized controlled trials (RCTs) through January 2022. Effect sizes were computed using Hedges’ g statistic, which were then entered into the random-effects model to obtain pooled effect estimates. Results: Twenty-four RCTs met the eligibility criteria. On the improvement of swallowing function, TNMES alone was not superior to conventional swallowing therapies (CSTs); combined therapy of TNMES and CSTs significantly surpassed CSTs alone (standardized mean difference (SMD) = 0.91, 95% confidence interval (95% CI): 0.68 to 1.14, p < 0.0001; I2 = 63%). Moreover, significant pooled effect sizes were observed in subgroups with horizontal electrode placement above the hyoid bone (SMD = 0.94, 95% CI: 0.72 to 1.16; I2 = 0%) and horizontal electrode placement just above and below the hyoid bone (SMD = 0.87, 95% CI: 0.59 to 1.14; I2 = 0%). The largest pooled effect size was observed in the subgroup that individualized electrode placement according to dysphagia evaluation (SMD = 1.65, 95% CI: 0.38 to 2.91; I2 = 90%). Conclusion: TNMES should be used in combination with CSTs for PSD. Horizontal electrode placement should target suprahyoid muscles or both suprahyoid and thyrohyoid muscles.

Transcutaneous Electrical Stimulation as a Resistance Force in Lingual Exercise: A Preliminary Proof-of-Concept Study

BACKGROUND

Limited knowledge exists regarding whether transcutaneous electrical stimulation (TES) based exercise can improve the lingual pressure generation.

OBJECTIVES

To compare the effect of submental TES with two different pulse durations (PD) coupled with isometric lingual exercises on lingual pressure measures.

METHODS

Twenty-eight healthy volunteers were divided into two submental TES groups: short PD (300 μs) and long PD (700 μs). The Iowa Oral Performance Instrument (IOPI) was used for lingual pressure measurements and exercise. In total, participants attended six exercise sessions three days per week for two consecutive weeks. Maximum and swallowing lingual pressures were measured one hour following each exercise session and three days after the final session to assess any detraining effect. Data were analyzed using repeated measure ANOVA.

RESULTS

Mean maximum lingual pressure change was significantly greater in TES with short PD versus the long PD condition following the first week of exercise. Following the two-week exercise, a significant increase was found in mean maximum lingual pressure for short and long PD conditions compared with the baseline. However, no significant difference was found between PD conditions for maximum lingual pressure. Likewise, no significant differences in swallowing lingual pressure were found compared with the baseline or across the two TES conditions.

CONCLUSION

Although short PD induced greater gain in maximum lingual pressure than the long PD after week 1, the enhanced effect faded after week 2, leading to a comparable increase in maximum lingual pressure for both groups. However, increased gain in maximum lingual pressure was not transferred to lingual pressure during swallowing.

Anatomical and physiological variation of the hyoid musculature during swallowing in infant pigs

The function of a muscle is impacted by its line of action, activity timing and contractile characteristics when active, all of which have the potential to vary within a behavior. One function of the hyoid musculature is to move the hyoid bone during swallowing, yet we have little insight into how their lines of action and contractile characteristics might change during a swallow. We used an infant pig model to quantify the contractile characteristics of four hyoid muscles during a swallow using synchronized electromyography, fluoromicrometry and high-speed biplanar videofluoroscopy. We also estimated muscle line of action during a swallow using contrast-enhanced CT-scanned muscles animated to move with the hyoid bone and found that as the hyoid elevated, the line of action of the muscles attached to it became greater in depression. We also found that muscles acted eccentrically and concentrically, which was correlated with hyoid movement. This work contributes to our understanding of how the musculature powering feeding functions during swallowing.

Effect of electromyography-triggered peripheral magnetic stimulation on voluntary swallow in healthy humans

BACKGROUND

Electrical stimulation therapy is effective for patients with dysphagia. However, because of the pain, strong stimulation cannot be applied. Although magnetic stimulation induces less pain, there are no reports on magnetic stimulation being synchronised with a swallowing reflex.

OBJECTIVE

This study aimed to determine whether it is possible to induce magnetic stimulation during a voluntary swallowing using electromyography (EMG)-triggered peripheral magnetic stimulation and to evaluate its effect on healthy individuals.

METHODS

A total of 20 healthy adults in seated position were instructed to swallow saliva and 10 ml of barium under videofluoroscopy. For concomitant use of magnetic stimulation, a magnetic stimulus for suprahyoid muscles at 30 Hz frequency was applied for 2 s when the EMG level in the sternohyoid muscle exceeded the threshold. During the voluntary swallowing, the movement of the hyoid bone and opening width of the upper oesophageal sphincter (UES) were measured. Furthermore, pressure topography was evaluated in 6 subjects using high-resolution manometry.

RESULTS

The magnetic stimulation significantly extended the movement time of the hyoid bone (p < 0.001). During liquid deglutition, significant increases were observed in the anterior maximum movement distance of the hyoid bone (p < 0.05), opening width of the UES (p < 0.001) and anterior movement distance of the hyoid bone at the maximum UES opening (p < 0.01). In the pressure topography, the maximum pressure immediately after UES closure significantly decreased with magnetic stimulation (p < 0.05).

CONCLUSION

EMG-triggered peripheral magnetic stimulation made it possible to apply magnetic stimulation during a voluntary swallowing.

Compensatory Effects of Sequential 4-Channel Neuromuscular Electrical Stimulation for the Treatment of Acute, Subacute, and Chronic Dysphagia in a Prospective, Double-Blinded Randomized Clinical Trial

Background. The precise mechanism of 2-channel neuromuscular electrical stimulation (NMES) treatment is unknown, and controversy remains over its efficacy. The sequential 4-channel NMES was newly developed based on normal contractile sequences of swallowing-related muscles. Objective. To assess the clinical efficacy of sequential 4-channel NMES during swallowing. Methods. In this prospective RCT, 52 inpatients with dysphagia (acute, subacute, and chronic state) after stroke, brain tumor, or encephalitis were enrolled. Participants who underwent a videofluoroscopic swallowing study (VFSS) and clinical evaluation were enrolled and were randomly assigned to the 4-channel NMES or sham group. The 4-channel NMES and sham groups swallowed thin and honey-like fluids under NMES (sequential stimulation on suprahyoid and infrahyoid) and sham stimulation, respectively. The procedures were evaluated with the VFSS. Pre- and post-treatment evaluations were performed with the videofluoroscopic dysphagia scale (VDS), penetration-aspiration scale (PAS), Likert scale, and kinematic analysis. Results. The 4-channel NMES group showed significantly greater improvements than the sham group with respect to oral VDS, pharyngeal VDS, total VDS, and PAS (P < .05). Furthermore, the Likert scale for satisfaction, easiness, and discomfort for swallowing showed favorable results for the 4-channel NMES group (P < .05). In the kinematic analysis, the peak speed point, distance, and velocity of hyoid movement were significantly greater in the 4-channel NMES group (P < .05). Conclusions. Sequential 4-channel NMES activating the suprahyoid, thyrohyoid, and other infrahyoid muscles during swallowing showed significant clinical improvement with respect to VDS, PAS, and kinematic analysis. Therefore, sequential 4-channel NMES is a potential new functional electrical stimulation system for the treatment of dysphagia.

Clinical effectiveness of the sequential 4-channel NMES compared with that of the conventional 2-channel NMES for the treatment of dysphagia in a prospective double-blind randomized controlled study

Background

To date, conventional swallowing therapies and 2-channel neuromuscular electrical stimulation (NMES) are standard treatments for dysphagia. The precise mechanism of 2-channel NMES treatment has not been determined, and there are controversies regarding the efficacy of this therapy. The sequential 4-channel NMES was recently developed and its action is based on the normal contractile sequence of swallowing-related muscles.

Objective

To evaluate and compare the rehabilitative effectiveness of the sequential 4-channel NMES with that of conventional 2-channel NMES.

Methods

In this prospective randomized case–control study, 26 subjects with dysphagia were enrolled. All participants received 2- or 4-channel NMES for 2–3 weeks (minimal session: 7 times, treatment duration: 300–800 min). Twelve subjects in the 4-channel NMES group and eleven subjects in the 2-channel NMES group completed the intervention. Initial and follow-up evaluations were performed using the videofluoroscopic dysphagia scale (VDS), the penetration-aspiration scale (PAS), the MD Anderson dysphagia inventory (MDADI), the functional oral intake scale (FOIS), and the Likert scale.

Results

The sequential 4-channel NMES group experienced significant improvement in their VDS (oral, pharyngeal, and total), PAS, FOIS, and MDADI (emotional, functional, and physical subsets) scores, based on their pretreatment data. VDS (oral, pharyngeal, and total) and MDADI (emotional and physical subsets) scores, but not PAS and FOIS scores, significantly improved in the 2-channel NMES group posttreatment. When the two groups were directly compared, the 4-channel NMES group showed significant improvement in oral and total VDS scores.

Conclusions

The sequential 4-channel NMES, through its activation of the suprahyoid and thyrohyoid muscles, and other infrahyoid muscles mimicking physiological activation, may be a new effective treatment for dysphagia.

Trial registration: clinicaltrial.gov, registration number: NCT03670498, registered 13 September 2018, https://clinicaltrials.gov/ct2/show/NCT03670498?term=NCT03670498&draw=2&rank=1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00884-6.

Assessment of Changes in Laryngeal Configuration and Voice Parameters Among Different Frequencies of Neuromuscular Electrical Stimulation (NMES) and Cumulative Effects of NMES in a Normophonic Subject: A Pilot Study

INTRODUCTION

Neuromuscular electrical stimulation (NMES) is a complementary resource to voice therapy that can be used for the treatment of hypofunctional voice disorders. Although positive clinical studies have been reported, neutral and even potentially harmful effects of NMES are also described in the literature. Furthermore, in the studies examined by the authors, the use of different methods of NMES have been identified, which further contributes to the inconsistent results found among studies. Moreover, limited rationale is provided for the chosen NMES parameters such as electrode placement, frequency of NMES and length of treatment. The aims of this pilot study were to investigate the a) impact of different frequencies of NMES on glottal configuration and vocal fold vibration patterns and b) changes in laryngeal configuration and vocal output across 12 minutes of NMES.

METHOD

Three experiments were carried out looking at changes in laryngeal configuration and voice output using different imaging techniques (fibreoptic nasolaryngoscopy and high-speed video), acoustical analysis (F0, formant analysis, SPL, CPPS and LHSR values), electroglottography (EGG) and Relative Fundamental Frequency (RFF) analyses. Glottal parameters and acoustical measures were recorded before, during, and after stimulation. Data was collected at rest and during phonation.

RESULTS

Overall the results showed global changes in laryngeal configuration from normal to hyperfunctional (ie, increased RFF, SPL, CQ, and stiffness). Changes were more pronounced for lower frequencies of NMES and were significant within less than three minutes of application.

CONCLUSION

NMES is an effective resource for the activation of intrinsic laryngeal muscles producing significant levels of adduction within few minutes of application. Lower NMES frequencies produced greater muscle activation when compared to higher frequencies.

Submandibular Push Exercise Using Visual Feedback from a Pressure Sensor in Patients with Swallowing Difficulties: A Pilot Study

Objectives: We aimed to determine the usefulness and effectiveness of a submandibular push exercise with visual feedback from a pressure sensor in patients with dysphagia through continuous exercise sessions. Methods: Twelve patients with dysphagia of various etiologies were included. A total of five exercise sessions (every 3 or 4 days) over three weeks were conducted. During the submandibular push exercise, patients were instructed to maintain a maximum force for 3 s, repeated for 1 min to measure the number of exercises, the maximum pressure, and the area of the pressure-time graph. We statistically compared the values of each exercise trial. Results: Among the 12 patients, eight completed the exercise sessions. As the number of exercise trials increased, the maximum pressure and the area in the pressure-time graph showed a significant increase compared to the previous attempt (p < 0.05). The maximum pressure and the area of the pressure-time graph improved from the first to the fourth session (p < 0.05). The values were maintained after the fourth session, and there was no significant difference between the fourth and the fifth exercise (p > 0.05). There was no significant difference between successful and non-successful groups, except for the Modified Barthel Index (p < 0.05). Conclusion: Through repetitive exercise training, the submandibular push exercise using visual feedback from a pressure sensor can be applied as an exercise method to strengthen swallowing related muscles, such as the suprahyoid and infrahyoid muscles. However, additional studies including more patients and a long-term study period are warranted to evaluate the effects of the exercise for improvement of dysphagia.

Comparison of three different types of exercises for selective contractions of supra- and infrahyoid muscles

Several exercise methods, such as the Shaker exercise, tongue press exercise, chin tuck against resistance (CTAR) exercise, and submandibular push exercise, have been introduced to strengthen the muscles involved in swallowing. In this study, we compared the effectiveness of the CTAR, submandibular push, and Shaker exercises for the induction of selective supra- and infrahyoid muscle contractions using surface electromyography (EMG). This study is a prospective non-randomized controlled study. Twenty-five healthy subjects and 20 patients experiencing swallowing difficulty were enrolled. During the three different types of exercises, the root mean square (RMS) values of the sternocleidomastoid (SCM), suprahyoid (anterior belly of the digastric and mylohyoid muscles), and infrahyoid (sternothyroid and thyrohyoid muscles) muscles were analyzed using surface EMG. Differences in the activity of swallowing muscles among the three different exercises were analyzed using one-way repeated measured analysis of variance. In terms of both the maximum and mean RMS values of the suprahyoid muscle, the submandibular push exercise showed a larger RMS value than the CTAR and Shaker exercises in healthy subjects (p < 0.05). In terms of both the maximum and mean RMS values of the suprahyoid muscle, the Shaker exercise and submandibular push exercise showed a larger RMS value than the CTAR exercise in patients with swallowing difficulty (p < 0.05). The submandibular push exercise may be effective as a swallowing muscle exercise owing to its superiority in inducing selective contractions of the supra- and infrahyoid muscles. The CTAR and Shaker exercises are also effective in this regard.

Effects of Varying Transcutaneous Electrical Stimulation Pulse Duration on Swallowing Kinematics in Healthy Adults

Prior research in swallowing physiology has suggested that using submental transcutaneous electrical stimulation (TES) with short pulse duration (PD) (300 μs) may enhance the impact on deep extrinsic tongue muscles, thereby pulling the tongue down during swallowing. However, it was unclear whether that same TES protocol could have a differential impact on hyolaryngeal kinematics and timing. This study aimed to compare the effect of submental TES with varying PDs on anterior and superior hyolaryngeal kinematics and timing both at rest and during swallowing in healthy adults. Twenty-four healthy adults between the ages of 22 and 77 participated in this study. Anterior and superior hyolaryngeal excursion magnitude and duration measures were collected using videofluoroscopic swallowing study. Each subject swallowed three 10 ml pudding trials under three conditions: no TES, TES with short PD (300 μs), and TES with long PD (700 μs). TES was delivered using two-channel surface electrodes in the submental area. In both short and long PD conditions, TES amplitude was gradually increased until participants reached their maximum tolerance level. Videofluoroscopic data were analyzed using VideoPad Video Editor and Image J programs. One-way repeated measure ANOVAs were conducted to identify within-subject effect of TES condition. For hyoid movement, TES with short PD selectively placed the hyoid bone on a more anterior position at rest and reduced anterior hyoid excursion during swallowing compared with the no TES condition. Regarding laryngeal movement, both TES protocols resulted in the larynx taking on a more anterior position at rest and reduced anterior laryngeal excursions during swallowing when compared with the no TES condition. Varying PDs had no significant effect on the superior hyoid and laryngeal movements at rest and during swallowing. Both TES protocols induced shorter hyoid elevation duration during swallowing Findings suggest that though both TES protocols demonstrated a comparable impact on reducing anterior laryngeal excursions, the TES protocol with short PD had an enhanced effect on reducing anterior hyoid excursion during swallowing. This reduced range of motion may result from stimulating the deep submental muscles, which primarily place the hyoid and larynx into a more forward position before swallowing onset. Overall, the TES protocol with short PD may have an increased benefit in facilitating swallowing in patients with dysphagia.

The effect of neuromuscular electrical stimulation with different electrode positions on swallowing in stroke patients with oropharyngeal dysphagia: A randomized trial

OBJECTIVE

To examine the effects of neuromuscular electrical stimulation (NMES) on oropharyngeal swallowing function according to 2 types of placement, acting as assistance and as resistance, in stroke patients with dysphagia.

METHODS

Thirty-eight stroke patients with dysphasia were randomly assigned to the suprahyoid group (SMG), or infrahyoid muscle group (IMG); 26 patients completed the intervention and were included in the analysis. In the SMG, the electrodes were placed on the region between the jaw and the hyoid bone, whereas in the IMG, the electrodes were placed on the region below the hyoid for the targeted infrahyoid muscles. Both groups received NMES for 30 min/d, 5 d/wk, for 4 weeks and conventional dysphagia therapy. Swallowing function was measured using the Videofluoroscopic Dysphagia Scale and Penetration-Aspiration Scale based on videofluoroscopic swallowing study. Oral dietary intake was measured using the Functional Oral Intake Scale.

RESULTS

Both groups showed significant improvements in oropharyngeal function and level of functional oral intake, but there was no significant difference between the two groups. However, the SMG showed a more reduced penetration-aspiration, compared with the IMG.

CONCLUSIONS

Altogether, these data demonstrate that 2 types of NMES placements have a similar effect on improving swallowing function and oral diet intake in patients with dysphagia.

Immediate effect of neuromuscular electrical stimulation on swallowing function in individuals after oral and oropharyngeal cancer therapy

Objective

To analyze the immediate effect of sensory and motor neuromuscular electrical stimulation, in oral and pharyngeal stages of swallowing, in individuals after oral and oropharyngeal cancer therapy.

Methods

The study was conducted on 10 individuals (mean age of 58 years) submitted to oral and oropharyngeal cancer therapy. The individuals were submitted to videofluoroscopy, during which they were randomly asked to swallow 5 mL of liquid, honey, and pudding, in three conditions: without stimulation, with sensory neuromuscular electrical stimulation, and with motor neuromuscular electrical stimulation. The degree of swallowing dysfunction was scored (Dysphagia Outcome and Severity Scale), as well as the presence of food stasis (Eisenhuber scale), and measurement of the oral and pharyngeal transit time. The results were statistically analyzed by the Friedman test or analysis of variance for repeated measures.

Results

The Dysphagia Outcome and Severity Scale revealed improvement for one individual with both sensory and motor stimuli, and worsening in two individuals, being one with motor and one with sensory stimulus. In the Eisenhuber scale, the neuromuscular electrical stimulation changed the presence of residues to variable extents. Concerning the oral and pharyngeal transit time, no difference was observed between the different stimulation levels for the consistencies tested (p > 0.05).

Conclusion

Both sensory and motor neuromuscular electrical stimulations presented a varied immediate impact on the oral and pharyngeal stages of swallowing in individuals after oral and oropharyngeal cancer therapy. Thus, the results of the immediate effect suggest that the technique is not indicated, evidencing the need of caution in the use of neuromuscular electrical stimulation for the rehabilitation of dysphagia, after HNC treatment.

Post-stroke Dysphagia: Recent Insights and Unanswered Questions

PURPOSE OF REVIEW

We explored themes in recent post-stroke dysphagia literature, focusing on the following questions: (1) What does post-stroke dysphagia look like?; (2) Who gets post-stroke dysphagia?; (3) What are the consequences of post-stroke dysphagia?; and (4) How can we improve treatment of post-stroke dysphagia?

RECENT FINDINGS

There have been several improvements in quantitative descriptions of swallowing physiology using standard and new evaluation techniques. These descriptions have been correlated with lesion locations, and several factors can predict development of post-stroke dysphagia and its sequelae. Novel treatment paradigms have leveraged post-stroke neuroplastic improvements using neurostimulation and biofeedback techniques. Despite recent findings, the field is limited by lack of standardization and unanswered questions on rehabilitation variables. Our improved understanding of post-stroke dysphagia will enhance our ability to prevent, identify, and treat it. Future work should be grounded in swallowing physiology and continue refining treatments, particularly in the acute stage.

Effect of the submandibular push exercise using visual feedback from pressure sensor: an electromyography study

We developed a new exercise method called the submandibular push exercise that can strengthen the suprahyoid muscle by inducing only the motion of the hyoid bone without neck flexion. In this study, we aimed to investigate and compare the muscle activity of the suprahyoid and infrahyoid muscles in the course of performing three different swallowing exercises. Twenty healthy participants and fifteen patients with dysphagia were recruited. Each participant consecutively performed three exercises: Shaker, CTAR, and submandibular push exercises. To investigate muscle activation, surface electromyography was performed on the suprahyoid, infrahyoid, and SCM muscles, during the exercises. Root mean square (RMS) was measured. In healthy participants, the submandibular push exercise showed a significantly higher RMS value in the suprahyoid and infrahyoid muscles than the Shaker and CTAR exercises using repeated ANOVA with Tukey's post hoc test (p < 0.05). In patients with dysphagia, the submandibular push and Shaker exercises showed significantly higher RMS value in the suprahyoid and infrahyoid muscles than the CTAR exercise. However, no significant difference was found between the submandibular push and Shaker exercises. In both healthy and patients with dysphagia, the mean RMS values of the SCM muscles during the submandibular push exercise were significantly lower than those during the Shaker exercise using repeated ANOVA with Tukey's post hoc test (p < 0.05). In conclusion, considering the relatively superior selectiveness in suprahyoid and infrahyoid muscle contraction, the submandibular push exercise using visual feedback from pressure sensor could be an efficient supplementary exercise to the conventional swallowing muscle exercises. However, further studies may be necessary to confirm the improvement in swallowing difficulty.

Transcutaneous Electrical Stimulation and Dysphagia Rehabilitation: A Narrative Review

Transcutaneous electrical stimulation (TES) was introduced as a modality for dysphagia rehabilitation more than a decade ago. The underlying premise of this modality is improving the structural movements and enhancing neural activation based on stimulation-induced muscle contractions. However, divisive evidence exists regarding the effectiveness of this treatment modality. This manuscript reviews current evidence regarding the effects of transcutaneous electrical stimulation (TES) on clinical and physiological aspects of swallowing function. Furthermore, this narrative review delineates the knowledge gap in this area and recommends future research roadmap. This review gives a comprehensive picture regarding current knowledge of TES to practicing speech and language pathologists and interested researchers. It highlights the need for more robust studies in this area. It also encourages researchers to focus more on the physiologic studies to understand the physiologic underpinning behind this treatment modality.

Swallow Motor Pattern Is Modulated by Fixed or Stochastic Alterations in Afferent Feedback

Afferent feedback can appreciably alter the pharyngeal phase of swallow. In order to measure the stability of the swallow motor pattern during several types of alterations in afferent feedback, we assessed swallow during a conventional water challenge in four anesthetized cats, and compared that to swallows induced by fixed (20 Hz) and stochastic (1-20Hz) electrical stimulation applied to the superior laryngeal nerve. The swallow motor patterns were evaluated by electromyographic activity (EMG) of eight muscles, based on their functional significance: laryngeal elevators (mylohyoid, geniohyoid, and thyrohyoid); laryngeal adductor (thyroarytenoid); inferior pharyngeal constrictor (thyropharyngeus); upper esophageal sphincter (cricopharyngeus); and inspiratory activity (parasternal and costal diaphragm). Both the fixed and stochastic electrical stimulation paradigms increased activity of the laryngeal elevators, produced short-term facilitation evidenced by increasing swallow durations over the stimulus period, and conversely inhibited swallow-related diaphragm activity. Both the fixed and stochastic stimulus conditions also increased specific EMG amplitudes, which never occurred with the water challenges. Stochastic stimulation increased swallow excitability, as measured by an increase in the number of swallows produced. Consistent with our previous results, changes in the swallow motor pattern for pairs of muscles were only sometimes correlated with each other. We conclude that alterations in afferent feedback produced particular variations of the swallow motor pattern. We hypothesize that specific SLN feedback might modulate the swallow central pattern generator during aberrant feeding conditions (food/liquid entering the airway), which may protect the airway and serve as potentially important clinical diagnostic indicators.

Swallowing dıfficulty and swallowing anxiety in patients with type-II diabetes mellitus

BACKGROUND

Type-II Diabetes Mellitus (TII-DM) is the most common endocrine disorder in people who are over 65 years of age. It leads to a decrease in muscle strength and impaired muscle coordination. Ageing and weakness cause swallowing difficulty (SD).

OBJECTIVE

The aim of this study was to evaluate the relationship between duration of disease, SD and swallowing anxiety (SA) in TII-DM patients.

STUDY DESIGN

Prospective case-control study.

METHODS

A total of 103 elderly individuals (74 females and 29 males) participated in this study. Fifty-two elderly patients (aged 70.27 ± 4.65 years) had a TII-DM and the duration of DM was 11.32 ± 10.03 years (minimum: 0-40 years). Fifty-one patients without diabetes mellitus (69.35 ± 3.58 years) were included in the control group. SD was determined using the EAT-10 Questionnaire. SA was evaluated with the Swallowing Anxiety Scale developed in the Turkish population. Handgrip strength was evaluated with a Jamar dynamometer on the dominant side.

RESULTS

There was a significant difference in SD (p : 0.042), SA (p : 0.001), and handgrip strength (p : 0.039) between groups. There was a relationship between SD and SA in the control and DM groups (r : 0.577; p : 0.000 and r : 0.663; p : 0.000, respectively). There was no relationship between the other parameters (age, SD, SA, and handgrip strength) in the control group (p < 0.05). There was a positive moderate relationship between SA and duration of disease in the TII-DM group (r : 0.472; p : 0.000). There was no relationship between other parameters (age, SD, SA, handgrip strength, and duration of disease) in the DM group (p < 0.05).

CONCLUSION

In elderly individuals with TII-DM and without DM, there were differences in SD, SA, and handgrip strength. Although there was a relationship between SD and SA in both groups, this relationship was found to be higher in elderly patients with TII-DM. In addition, there was a relationship between the duration of diagnosis and SA. In elderly individuals, evaluating SD with SA was thought to be helpful in the prevention or early rehabilitation of swallowing disorders.

How a personalised transportable folding device for seating impacts dysphagia

PURPOSE

A personalised transportable folding device for seating (DATP) on a standard seat was developed by an occupational therapist at the Toulouse University Hospital Centre (patent no. WO 2011121249 A1) based on the hypothesis that the use of a seat to assist with better positioning on any chair during meals modifies the sitting posture and has an impact on cervical statics which increases the amplitude of movements of the axial skeleton (larynx and hyoid bone) and benefits swallowing. The aim of this work is to demonstrate that an improvement in sitting posture with the help of the DATP, through Hyoid bone motion, has an impact on the quality of swallowing in a dysphagic population which benefits from the device in comparison to a dysphagic population which does not benefit from the device after 1 month of care. The secondary endpoints concern the evaluation of the impact on other characteristics of swallowing, posture, the acceptability of the device and the quality of life.

METHODOLOGY

This is a randomised comparative clinical trial. The blind was not possible for the patients but the examiner who evaluated the outcome criterion was blinded to the group to which the patient belonged. The outcome criterion was the measurement of the hyoid bone movement during swallowing. The other criteria were collected during the videofluoroscopic examination of swallowing and by use of a questionnaire. Fifty-six (56) patients were included: 30 in the group without device (D-) and 26 in the group with the device (D+). All the patients benefited from a training course on seating. Only the D+ patients participated in this course where the use of the device was explained and the device was then kept for use at home for 1 month.

RESULTS

A significant improvement was noted in the postural criteria before and after use, in favour of a better posture for the two groups (p < 0.001) and more hyoid bone motion in the D+ group. The difference was significant in the bivariate analysis for horizontal movement (p = 0.04). After adjustment of potential factors of confusion, we noted a significant mean difference for the three distances in the D+ group in comparison to the D- group, of + 0.33 (95% CI [+ 0.17; + 0.48]) for horizontal movement, + 0.22 (95% CI [+ 0.03; + 0.40]) for vertical movement and + 0.37 (95% CI = [+ 0.20; + 0.53]) for horizontal movement. However, the other parameters, and notably the other swallowing markers were not significantly modified by the use of the device.

CONCLUSION

The personalised transportable folding device for seating developed to reduce dysphagia has an action on hyoid bone motion during swallowing. However, this positive effect on an intermediate outcome criterion of the quality of swallowing was not associated with an improvement in swallowing efficiency in the study population. The diversity of diseases with which the patients in this study were afflicted is a factor to be controlled in future studies with this device.

Optimal placement of electrodes for treatment of post-stroke dysphagia by neuromuscular electrical stimulation combined with effortful swallowing

INTRODUCTION

We aimed to determine the optimal placement of electrodes for neuromuscular electrical stimulation (NMES) for post-stroke dysphagia therapy.

METHODS

31 patients with post-stroke dysphagia were randomised to three groups according to NMES electrode placement. In Group A (n = 10), two pairs of electrodes were attached horizontally on the suprahyoid and infrahyoid muscles. In Group B (n = 11), one pair of electrodes was attached horizontally on the suprahyoid muscles while the other was attached vertically on the infrahyoid muscles. In Group C (n = 10), the electrodes were attached vertically, with one pair above the hyoid bone and the other above the cricoid cartilage. All patients received rehabilitation treatment via NMES combined with effortful swallowing training five times weekly for four weeks. The effect of NMES electrode placement was assessed in terms of the Functional Dysphagia Scale (FDS) and Dysphagia Outcome and Severity Scale (DOSS) scores.

RESULTS

Group A showed significantly greater improvement than Group B in overall FDS (p = 0.009) and pharyngeal-phase FDS (FDS-P; p = 0.005) scores. Group A also showed significant improvement when compared with Group C in overall FDS (p = 0.001) and FDS-P (p = 0.001) scores.

CONCLUSION

Horizontal placement of the NMES electrodes on the suprahyoid and infrahyoid muscles for the treatment of post-stroke dysphagia by NMES combined with effortful swallowing was more effective than the horizontal and vertical placement of electrodes on the suprahyoid and infrahyoid muscles, respectively, and their vertical placement above the hyoid bone and cricoid cartilage.

The Effects of Electrical Stimulation Pulse Duration on Lingual Palatal Pressure Measures During Swallowing in Healthy Older Adults

Limited research in swallowing physiology has suggested that the most common existing transcutaneous electrical stimulation (TES) protocol (VitalStim) may not penetrate to layers of tissue to affect deep swallowing muscles. TES amplitude is the primary parameter that determines the depth of electrical current penetration (DECP). Preliminary work suggests that replacing a long-pulse duration with a short-pulse duration can increase maximum amplitude tolerance (MAT) within subjects' comfort level. Increasing MAT may indicate a higher DECP. The current study evaluates this premise in reference to the effects of varying pulse duration on lingual-palatal pressure during swallowing. Thirty healthy older adults (60-70 years of age) participated in this study. Each subject swallowed three trials of 10 mL pudding under three TES conditions: no stimulation, short-pulse duration, and long-pulse duration. TES was delivered using two pairs of surface electrodes on the submental muscles. MAT and perceived discomfort levels were identified separately for short and long-pulse TES conditions. Lingual-palatal peak pressure, pressure integral, and pressure duration were measured under each condition. Two-way repeated measures ANOVAs were conducted to identify within subject effects of TES condition and tongue bulb location. Lingual-palatal pressure and pressure integral were significantly reduced in the short-pulse duration condition. MAT was significantly higher in the short-pulse duration versus the long-pulse duration condition. Furthermore, MAT was significantly correlated with lingual-palatal pressure. Changing pulse duration had no significant impact on tongue pressure duration. Results suggest that a short-pulse duration may penetrate deeper into muscles involved in swallowing. The specific impact is reflected in a reduced upward pressure of the tongue on the palate during swallowing. This 'restrictive' effect of TES on tongue pressure may have the potential to be used during a resistive exercise paradigm for tongue elevation during swallowing.

Efeito imediato da estimulação elétrica neuromuscular na deglutição após tratamento do câncer de laringe: relato de caso

RESUMO Este trabalho teve por objetivo verificar o efeito imediato da Estimulação Elétrica Neuromuscular (EENM) sensorial e motora, nas fases oral e faríngea da deglutição, em um homem de 64 anos, após tratamento de câncer de laringe. Foi realizado exame de videofluoroscopia durante a deglutição de 5 ml de mel e pudim, em três condições: sem estimulação, com EENM sensorial, com EENM motora, definidas de forma randomizada. Foi classificado o grau da disfunção da deglutição (DOSS), a presença de estase de alimentos (escala de Eisenhuber), de penetração laríngea e aspiração laringotraqueal (PAS), além da medida do tempo de trânsito oral e faríngeo, realizadas por uma avaliadora sem conhecimento sobre o estímulo aplicado. Na escala DOSS, houve melhora com a estimulação sensorial e motora. Na escala PAS, verificou-se melhora, tanto para o estímulo sensorial quanto motor na consistência mel, porém observou-se piora no estímulo motor para a consistência pudim. Houve diminuição dos resíduos em base de língua com estímulo sensorial e motor para as consistências pudim e mel; piora no estímulo motor na parede posterior da faringe para a consistência mel. Em relação ao tempo de trânsito oral e faríngeo, não foi observada diferença entre os níveis de estimulações. Os resultados demonstraram que a EENM em nível sensorial e motor melhorou o grau da disfagia em um indivíduo após o tratamento de câncer de laringe, com maiores benefícios do nível sensorial em relação ao motor no que diz respeito à presença de penetração e resíduos.

Effects of Submental Surface Electrical Stimulation on Swallowing Kinematics in Healthy Adults: An Error-Based Learning Paradigm

PURPOSE

Hyoid bone and laryngeal approximation aid airway protection (laryngeal vestibule closure) while moving toward their peak superior and anterior positions during swallowing. Submental surface electrical stimulation (SES) is a therapeutic technique that targets the muscles that move the hyoid bone during swallowing. It is unknown whether submental SES only increases peak hyoid bone swallowing positions but not peak laryngeal swallowing positions, which could require faster or greater laryngeal movement to achieve adequate laryngeal vestibule closure.

METHOD

We examined the effects of submental SES on hyo-laryngeal kinematics in 30 healthy adults who swallowed 50 times using an error-based learning paradigm.

RESULTS

Submental SES did not alter any hyo-laryngeal swallowing kinematic. However, submental SES significantly changed the starting position of the hyoid bone just prior to the swallow onset (more anterior; p = .003). On average, submental SES immediately prior to swallow onset can position the hyoid approximately 20% closer to its peak swallowing point.

CONCLUSIONS

These findings indicate that electrical stimulation of the agonists for hyoid movement might not alter swallowing outcomes tested in this study. However, submental SES could have clinical utility by minimizing swallowing impairments related to reduced hyoid swallowing range of motion in individuals with dysphagia.

A new flexible piezoelectric pressure sensor array for the noninvasive detection of laryngeal movement during swallowing

We tried to develop a new device to detect laryngeal movement noninvasively. We made small piezo pressure sensors (length, 1.5 mm, width, 7.0 mm), and five of these were lined up with 3.0-mm intervals and embedded in the middle of a palm-sized urethane resin sheet. This sheet was lightly attached to the ventral surface of the neck near the laryngeal prominence. The first and second peaks obtained from each sensor should correspond to the period when the larynx moves to the upper and lower positions during swallowing. The mean maximum rising velocities for men and women were about 0.08 and 0.11 m/s, respectively. Similarly, the mean maximum lowering velocities for men and women were about 0.09 and 0.11 m/s, respectively. The swallowing latencies for men and women were about 0.49 and 0.53 s, respectively. In conclusion, we succeeded in developing a new device, which will be useful in evaluating the swallowing function.

The effect of surface neuromuscular electrical stimulation on patients with post-stroke dysphagia

OBJECTIVE

To assess whether the clinical efficacy of a therapeutic protocol using surface neuromuscular electrical stimulation (sNMES) on patients with post-stroke dysphagia (PSD) is superior to that without sNMES, and whether swallowing functional outcome is different with regards to different electrode placement on patients' skin of neck.

METHODS

Thirty patients with PSD were randomly allocated into treatment group A (TGA), treatment group B (TGB) and control group according to a random number table. The three groups of patients all received traditional dysphagia therapy (TDT) and other general rehabilitation therapy such as physical therapy and occupational therapy as a basic treatment project. Besides this, sNMES treatment was applied on different sites of patients' neck skin in group A and B separately. All the patients received video-fluoroscopic swallowing study (VFSS) pre-treatment and 2 weeks post-treatment, during which the displacement of the hyolaryngeal complex towards the superior and anterior sides while swallowing semi-liquid diet were measured. Outcome of the VFSS was measured using dysphagia outcome and severity scale (DOSS).

RESULTS

Post-treatment evaluation was carried out using water swallow test (WST), repetitive saliva swallowing test (RSST) and dysphagia outcome and severity scale (DOSS) from the three study groups were all improved (P< 0.05). The results of post-treatment evaluation using WST from TGA and TGB were 2.40 ± 1.26 and 2.10 ± 0.99 respectively, using RSST from TGA and TGB were 5.30 ± 1.89 and 5.20 ± 1.69 respectively, using DOSS from TGA and TGB were 5.20 ± 1.40 and 5.10 ± 1.45 respectively. Compared to control group, the results of post-treatment evaluation using the three scales, there were significant improvement between TGA and TGB (P< 0.05), however, the inter-group differences of TGA and TGB indicated no statistically significant difference (P> 0.05). The post-treatment evaluation of the moving distance of hyoid bone towards anterior side in swallowing was significantly improved as compared to TGB (-8.40 ± 7.48, t=-3.552, P= 0.006), and was statistically significant as compared to the control group (P> 0.05).

CONCLUSIONS

Swallowing function in the patients with PSD was significantly improved using TDT combined with NMES. Stimulating electrodes placed at the suprahyoid region or on both suprahyoid and infrahyoid regions resulted in no difference of effect. However, NMES on suprahyoid region could further improve the moving distance of hyoid bone anteriorly.

"Hidden in Plain Sight": A Descriptive Review of Laryngeal Vestibule Closure

A major emphasis in the evaluation of swallowing is to identify physiological abnormalities in swallowing that contribute to or explain unsafe swallowing (i.e., ingested material enters the trachea; post-swallow residue in the pharynx). Impairments in laryngeal vestibule closure are widely recognized as one of the major causes of unsafe swallowing, as it is the primary mechanism and first line of defense for preventing material from penetrating the airway during swallowing. However, this complex mechanism is often overlooked and understudied in swallowing research and dysphagia management. The purpose of this review is to promote a better understanding of the mechanism of laryngeal vestibule closure. We discuss where gaps in research exist and propose future directions for incorporating laryngeal vestibule closure as a primary outcome measure in swallowing research. Additionally, we propose that an increased knowledge of the mechanism of laryngeal vestibule closure will increase diagnostic accuracy and optimize dysphagia management for patients with dysphagia.

Transcutaneous electrical stimulation on the anterior neck region: The impact of pulse duration and frequency on maximum amplitude tolerance and perceived discomfort

Maximum amplitude tolerance (MAT) has been known as a primary factor determining the depth of electrical current penetration. However, the effect of varying transcutaneous electrical stimulation (TES) parameters on MAT and discomfort level is poorly understood. Furthermore, limited information exists regarding the biopsychological factors that may impact MAT and discomfort. The primary aims of this study were to compare the effects TES protocol with varying levels of pulse duration (300 μs vs 700 μs) and frequency (30 Hz vs 80 Hz) on the MAT and discomfort in healthy older adults. The exploratory aim of this study was to examine relationships between submental adipose tissue thickness, pain sensitivity and gender with MAT and discomfort. Twenty-four healthy older adults participated in this study. Transcutaneous electrical stimulation was delivered to the submental region. Maximum amplitude tolerance and discomfort were measured for each condition. Furthermore, submental adipose tissue thickness and pain sensitivity were measured for each subject. Maximum amplitude tolerance was significantly increased for the TES protocols with short-pulse duration [F (3, 69) = 38.695, P < .0001]. Discomfort was similar across different TES protocols. Submental adipose tissue thickness (r = .30, P < .003) and pain sensitivity (r = -.43, P < .0001) were related to MAT. Pain sensitivity rating was also related to discomfort (r = .45, P < .0001). In conclusion, using TES protocols with short-pulse duration may increase the MAT. Higher amplitude stimulation may increase the impact on deep swallowing muscles. In addition, submental adipose tissue thickness and pain sensitivity are potential biopsychological factors that may affect MAT and discomfort.

A study of VHI scores and acoustic features in street vendors as occupational voice users

PURPOSE

to investigate acoustic features of phonation and perception of voice handicap in street vendors.

METHODS

Eighty-eight participants (44 street vendors, 44 controls) were recruited. The mean age of the group was 38.9±16.0 years (range: 20-78 years). Scores of the Arabic version of the Voice Handicap Index (VHI-Arab) were used for analysis. Acoustic measures of fundamental frequency (F₀), jitter, shimmer, and signal-to-noise ratio (SNR) were also analyzed.

RESULTS

Analysis showed a significant difference between street vendors and controls in the total score of the VHI-Arab (p<0.001) as well as scores of all three VHI-Arab subsections: functional (p<0.001), physical (p<0.001), and emotional (p=0.025). Weak correlations were found among all of the VHI scores and acoustic measures (-0.219≤ r≤0.355), except for SNR where a moderate negative correlations were found (r=-0.555; -0.4) between the VHI (physical and total) scores and SNR values. Significant differences also were found in F₀, jitter, and SNR among specific subgroups of street vendors when stratified by weekly hours worked (p<0.05), and in jitter (p=0.39) when stratified by educational level.

CONCLUSIONS

Perception of voice handicap and a possible effect on vocal quality in street vendors were noted. The effect of factors, namely work hours and educational level, on voice quality should be further studied.

Excessive anterior cervical muscle tone affects hyoid bone kinetics during swallowing in adults

Purpose

This study aimed to determine whether excessive neck muscle tone affects hyoid bone kinetics during swallowing using videofluorography (VF) in an unnatural posture in healthy individuals.

Subjects and methods

Subjects were 28 healthy adults (12 men, 16 women; mean age, 39.75±9.50 years) without any history or present complaints of swallowing disorders. We first established the participant’s posture a reclining wheelchair that was adjusted to a 30-degree angle with the headrest (without excessive neck muscle tone) or without headrest (with excessive neck muscle tone), used an electromyogram above the mylohyoid muscle to represent the suprahyoid muscles and above the sternohyoid muscle to represent the infrahyoid muscles to confirm neck muscle tone, and then conducted VF of swallowing measurements. Videofluorographic images were obtained when 5 mL of 50% (w/v) barium sulfate was being swallowed, and hyoid bone coordinate (the resting position and the elevated position), extent of horizontal and vertical hyoid bone elevation, as well as duration and velocity of hyoid bone elevation were evaluated (x-axis and y-axis coordinates for the resting position of hyoid bone are referred to as Xr and Yr, respectively; those for the elevated hyoid bone position induced during swallowing are referred to as Xs and Ys, respectively).

Results

In the resting position of the hyoid bone, the Yr coordinates in those with excessive neck muscle tone were significantly lower than in those without excessive neck muscle tone. Vertical hyoid bone elevation and hyoid bone elevation velocity were significantly higher with excessive neck muscle tone than without excessive neck muscle tone, whereas horizontal elevation showed no significant differences.

Conclusion

Our findings suggest that the generation of neck muscle tone due to inappropriate posture may encourage hyoid depression and increase the extent of hyoid bone elevation, thereby increasing the risk of aspiration.

Immediate effect of laryngeal surface electrical stimulation on swallowing performance

Surface electrical stimulation of the laryngeal region is used to improve swallowing in dysphagic patients. However, little is known about how electrical stimulation affects tongue movements and related functions. We investigated the effect of electrical stimulation on tongue pressure and hyoid movement, as well as suprahyoid and infrahyoid muscle activity, in 18 healthy young participants. Electrical stimulation (0.2-ms duration, 80 Hz, 80% of each participant's maximal tolerance) of the laryngeal region was applied. Each subject swallowed 5 ml of barium sulfate liquid 36 times at 10-s intervals. During the middle 2 min, electrical stimulation was delivered. Tongue pressure, electromyographic activity of the suprahyoid and infrahyoid muscles, and videofluorographic images were simultaneously recorded. Tongue pressure during stimulation was significantly lower than before or after stimulation and was significantly greater after stimulation than at baseline. Suprahyoid activity after stimulation was larger than at baseline, while infrahyoid muscle activity did not change. During stimulation, the position of the hyoid at rest was descended, the highest hyoid position was significantly inferior, and the vertical movement was greater than before or after stimulation. After stimulation, the positions of the hyoid at rest and at the maximum elevation were more superior than before stimulation. The deviation of the highest positions of the hyoid before and after stimulation corresponded to the differences in tongue pressures at those times. These results suggest that surface electrical stimulation applied to the laryngeal region during swallowing may facilitate subsequent hyoid movement and tongue pressure generation after stimulation. NEW & NOTEWORTHY Surface electrical stimulation applied to the laryngeal region during swallowing may facilitate subsequent hyoid movement and tongue pressure generation after stimulation. Tongue muscles may contribute to overshot recovery more than hyoid muscles.

Evidence that an internal schema adapts swallowing to upper airway requirements

KEY POINTS

To swallow food and liquid safely, airway protection is essential. Upward and forward movements of the hyoid and larynx in the neck during swallowing vary in magnitude between individuals. In healthy human adults, hyoid and laryngeal movements during swallowing were scaled by differences in initial upper airway area before swallowing. Individuals increased laryngeal elevation during swallowing in response to increased airway opening before swallowing. We show that when upper airway protection requirements change, individuals use an internal sensorimotor scaling system to adapt movements to maintain swallow safety.

ABSTRACT

Hyoid and laryngeal movements contribute to laryngeal vestibule closure and upper oesophageal sphincter opening during swallowing. Evidence of an internal sensorimotor scaling system allowing individuals to achieve these functional goals is lacking. In speech, speakers adjust their articulatory movement magnitude according to the movement distance required to reach an articulatory target for intelligible speech. We investigated if swallowing is similar in that movement amplitude may be scaled by the functional goal for airway protection during swallowing, rather than by head and neck size. We hypothesized that healthy individuals adapt to their own anatomy by adjusting hyo-laryngeal movements to achieve closure of the upper airway. We also investigated if individuals would automatically compensate for changes in their initial hyo-laryngeal positions and area when head position was changed prior to swallowing. Videofluoroscopy was performed in 31 healthy adults. Using frame-by-frame motion analysis, anterior and superior hyoid and laryngeal displacement, and hyo-laryngeal area were measured prior to and during swallowing. Kinematic measurements during swallowing were examined for relationships with pharyngeal neck length, and initial hyo-laryngeal positions, length and area before swallowing. During swallowing, individuals altered laryngeal elevation magnitude to exceed hyoid elevation based on hyo-laryngeal length before swallowing. Anterior laryngeal displacement was related to initial larynx distance from the spine, while hyoid elevation was predicted by pharyngeal neck length and initial hyoid distance from the mandible prior to the swallow. In conclusion, individuals automatically adapt hyo-laryngeal movement during swallowing based on targets required for closing the hyo-laryngeal area for safe swallowing.