Electromyographic activity from human laryngeal, pharyngeal, and submental muscles during swallowing

Assessing the oral and suprahyoid muscles in healthy adults using muscle ultrasound to inform the swallowing process: a proof-of-concept study

The oral and suprahyoid muscles are responsible for movements of swallowing. Our study aimed to determine the reproducibility of static and dynamic measurements of these muscles using bedside ultrasound equipment. Forty healthy participants were recruited prospectively. Primary outcomes were evaluation of mass measurements of the anterior bellies of the digastric, mylohyoid, geniohyoid and tongue in B-mode ultrasound. Secondary outcomes were evaluation of geniohyoid muscle layer thickness and function using M-mode. Muscle mass measurements demonstrated little within-participant variability. Coefficient of Variance (CoV) across muscles were: anterior belly digastric (5.0%), mylohyoid (8.7%), geniohyoid (5.0%) and tongue (3.2%). A relationship between sex (r2 = 0.131 p = 0.022) was demonstrated for the geniohyoid muscle, with males having higher transverse Cross Sectional Area (CSA) (14.3 ± 3.6 mm vs. 11.9 ± 2.5 mm, p = 0.002). Tongue size was correlated with weight (r2 = 0.356, p = 0.001), height (r2 = 0.156, p = 0.012) and sex (r2 = 0.196, p = 0.004). Resting thickness of the geniohyoid muscle layer changed with increasing bolus sizes (f = 3.898, p = 0.026). Velocity increased with bolus size (p =  < 0.001, F = 8.974). However swallow time and slope distance did not, potentially influenced by higher coefficients of variation. Oral and suprahyoid muscle mass are easily assessed using bedside ultrasound. Ultrasound may provide new information about muscle mass and function during swallowing.

Comparison of Two Types of Electrodes for Measuring Submental Muscle Activity During Swallowing

PURPOSE

This study aimed to investigate the potential of a newly developed small electrode to accurately record muscle activity during swallowing.

MATERIAL AND METHODS

This study included 31 healthy participants. The participants underwent swallowing trials with three types of material. The recordings involved the following conditions: 1) swallowing saliva, 2) swallowing 3 mL water, and 3) swallowing 5 mL water. Two types of electrodes, a conventional electrode (CE) and a newly developed small electrode (NE), were symmetrically positioned on the skin over the suprahyoid muscle group, starting from the center. From the surface electromyography data, the swallowing duration (s), peak amplitude, and rising time (duration from swallowing onset to peak amplitude: s) were measured. Additionally, the equivalence of characteristics of the waveform of muscle activities was calculated by using the variance in both the upper and lower confidence limits in duration and rising time.

RESULTS

No significant differences in baseline, swallowing duration or rising time between the CE and NE were observed for any swallowing material. The peak amplitude was significantly higher for the NE than for the CE for all swallowing materials. The CE and NE displayed no significant difference in the equivalence of characteristics of the waveform of muscle activities for any swallowing material.

CONCLUSIONS

The gold-plated small electrodes utilized in this study indicated the ability to record the same characteristics of muscle activity as conventional electrodes. Moreover, it was able to capture the muscle activity of each muscle group with improved sensitivity in a narrow area, such as under the submandibular region, with more precision than that of conventional electrodes.

Comparison of Submental Surface Electromyography during Dry Swallow between Irradiated Head and Neck Cancer Survivors and Normal Individuals

INTRODUCTION

This study compared the submental surface electromyography (sEMG) duration and amplitude during dry swallowing between irradiated head and neck cancer (HNC) survivors and age-matched normal individuals. Further, the relationship between submental and infrahyoid sEMG in the irradiated HNC group was explored.

METHOD

Forty participants (20 HNC survivors and 20 age-matched normal individuals) participated in this study. The HNC survivors had completed organ preservation cancer treatment (at least 1-month post-treatment). They were on a complete oral diet without enteral supplementation (FOIS score> 4). Submental and infrahyoid sEMG activity was calculated for three trials of saliva swallow for each participant using sEMG. The duration and amplitude parameters considered were: onset duration - duration from the onset of swallowing to the maximum amplitude, offset duration - duration from the maximum amplitude to the end of the swallowing activity, total duration, and maximum amplitude.

RESULTS

The study found that irradiated HNC survivors exhibited prolonged temporal measures, particularly in the offset duration, which suggested a delayed descent of the hyolaryngeal complex during swallowing. Additionally, the HNC group showed a positive correlation between submental and infrahyoid sEMG. Furthermore, it was observed that the rate of increase in the duration of submental sEMG during subsequent swallowing was greater in HNC survivors which could be due to reduced salivation.

CONCLUSION

Compared to age-matched normal individuals, irradiated HNC survivors manifest alterations in the submental muscle activities during dry swallowing as measured using sEMG. The temporal and amplitude changes are likely to have arisen as a consequence of postradiation changes.

Surface Electromyographic Activity of the Masseter Muscle During Regular and Effortful Saliva Swallows: A Preliminary Study

Biofeedback is a critical component in motor learning of new, complex behaviors such as modifications to swallowing. Surface electromyography (sEMG) is a commonly employed biofeedback tool in swallowing management to assess muscle activity patterns, determine amplitude and duration of swallowing, and train swallowing strategies such as the effortful swallow (EFS) maneuver. The EFS can potentially change multiple physiological components of the swallowing process such as pressure generation and movement of biomechanical structures. The purposes of this study were to determine whether the masseter muscle could differentiate a normal swallow (NS) from an EFS and whether there was a relationship between perceived muscle effort used to swallow and objective measures of muscle activity. Twenty healthy young adults participated in this study. Masseter sEMG peak amplitude and duration were measured across five regular saliva swallows and five effortful saliva swallows. Additionally, participants rated their perceived swallowing effort using a visual analog scale (VAS). Two swallowing conditions, NSs and EFSs were compared with hierarchical models, and repeated measures correlation was used to determine the relationships between the VAS and sEMG peak amplitude. Participants produced swallows with greater masseter sEMG peak amplitude and duration during the EFS. Moreover, a positive correlation was identified between perceived swallowing effort and masseter sEMG peak amplitude. These findings support the potential use of the masseter muscle to differentiate NSs from EFSs and implement the VAS during therapy for tracking patients' performance, particularly in settings with limited access to sEMG.

Neuromuscular adaptations of swallowing and speech in unilateral cerebral palsy: shared and distinctive traits

Our aims were to 1) examine the neuromuscular control of swallowing and speech in children with unilateral cerebral palsy (UCP) compared with typically developing children (TDC), 2) determine shared and separate neuromuscular underpinnings of the two functions, and 3) explore the relationship between this control and behavioral outcomes in UCP. Surface electromyography (sEMG) was used to record muscle activity from the submental and superior and inferior orbicularis oris muscles during standardized swallowing and speech tasks. The variables examined were normalized mean amplitude, time to peak amplitude, and bilateral synchrony. Swallowing and speech were evaluated using standard clinical measures. Sixteen children with UCP and 16 TDC participated (7-12 yr). Children with UCP demonstrated higher normalized mean amplitude and longer time to peak amplitude across tasks than TDC (P < 0.01; and P < 0.02) and decreased bilateral synchrony than TDC for swallows (P < 0.01). Both shared and distinctive neuromuscular patterns were observed between swallowing and speech. In UCP, higher upper lip amplitude during swallows was associated with shorter normalized mealtime durations, whereas higher submental bilateral synchrony was related to longer mealtime durations. Children with UCP demonstrate neuromuscular adaptations for swallowing and speech, which should be further evaluated for potential treatment targets. Furthermore, both shared and distinctive neuromuscular underpinnings between the two functions are documented.NEW & NOTEWORTHY Systematically studying the swallowing and speech of children with UCP is new and noteworthy. We found that they demonstrate neuromuscular adaptations for swallowing and speech compared with typically developing peers. We examined swallowing and speech using carefully designed tasks, similar in motor complexity, which allowed us to directly compare patterns. We found shared and distinctive neuromuscular patterns between swallowing and speech.

A fully integrated, standalone stretchable device platform with in-sensor adaptive machine learning for rehabilitation

Post-surgical treatments of the human throat often require continuous monitoring of diverse vital and muscle activities. However, wireless, continuous monitoring and analysis of these activities directly from the throat skin have not been developed. Here, we report the design and validation of a fully integrated standalone stretchable device platform that provides wireless measurements and machine learning-based analysis of diverse vibrations and muscle electrical activities from the throat. We demonstrate that the modified composite hydrogel with low contact impedance and reduced adhesion provides high-quality long-term monitoring of local muscle electrical signals. We show that the integrated triaxial broad-band accelerometer also measures large body movements and subtle physiological activities/vibrations. We find that the combined data processed by a 2D-like sequential feature extractor with fully connected neurons facilitates the classification of various motion/speech features at a high accuracy of over 90%, which adapts to the data with noise from motion artifacts or the data from new human subjects. The resulting standalone stretchable device with wireless monitoring and machine learning-based processing capabilities paves the way to design and apply wearable skin-interfaced systems for the remote monitoring and treatment evaluation of various diseases.

Surface Electromyography for Evaluating the Effect of Aging on the Coordination of Swallowing Muscles

Swallowing function can deteriorate with age, leading to a risk of dysphagia. Swallowing evaluation by surface electromyography (sEMG) can be easily and extensively applied for an elderly population. This study evaluated the temporal events observed by sEMG to clarify how aging affects the coordination among the masticatory and suprahyoid muscles. We recruited elderly individuals (over 65 years old) who denied dysphagia. The sEMG activities of anterior temporalis, masseter, and suprahyoid muscles were recorded during 3, 15, and 30 ml water swallowing tests (WST). We calculated the time interval between anterior temporalis and suprahyoid peak activity (T-SH interval) and masseter and suprahyoid peak activity (M-SH interval) and analyzed their correlation with age. The subjects who could and could not swallow 30 ml of water in one gulp were further assigned into the one-gulp and piecemeal groups, respectively, for subgroup analysis. We recruited 101 subjects, among whom 75 (26 males and 49 females) were analyzed after excluding those with suspected dysphagia or low-quality sEMG recordings. Age was significantly correlated with the bilateral T-SH (left: r = 0.249, p = 0.031; right: r = 0.412, p < 0.01) and right M-SH (r = 0.242, p = 0.037) intervals in the 30 ml WST. The correlation between intervals and age were observed in both subgroups. sEMG can be used to investigate the effect of aging on the temporal coordination between masticatory and suprahyoid contraction. Further studies are needed to verify the validity of screening subclinical dysphagia in the elderly.

Shared and Separate Neuromuscular Underpinnings of Swallowing and Motor Speech Development in the School-Age Years

PURPOSE

Despite co-occurrence of swallowing and speech disorders in childhood, there is limited research on shared and separate neuromuscular underpinnings of these functions. The purpose of this study was to (a) compare neuromuscular control of swallowing and speech between younger and older children and (b) determine similarities and differences in neuromuscular control of swallowing and speech.

METHOD

Twenty-six typically developing children (thirteen 7- to 8-year-olds and thirteen 11- to 12-year-olds) completed this cross-sectional study. Neuromuscular control was evaluated using surface electromyography of submental muscles and superior and inferior orbicularis oris muscles during parallel tasks of swallowing and speech. Outcome measures included normalized mean amplitude, burst duration, time to peak amplitude, and bilateral synchrony, which were examined using mixed-effects models.

RESULTS

For normalized mean amplitude, burst duration, and time to peak amplitude, there were significant two- and three-way interactions between muscle group, task, and age group, indicating that older and younger children demonstrated different muscle activation patterns, and these patterns varied by muscle and task. No differences were noted between groups for bilateral synchrony. For parallel tasks, children demonstrated different magnitudes of normalized mean amplitude and time to peak amplitude of speech and swallowing. However, they demonstrated a similar pattern: increases in magnitude as task complexity increased.

CONCLUSIONS

Children continue to demonstrate refinement of their neuromuscular control of swallowing and speech between 7-8 and 11-12 years of age, and there are both shared and separate elements of neuromuscular control between these two vital functions. To improve generalizability of findings, future research should include longitudinal analysis of swallowing and speech development, as well as measures of central neurophysiology.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23796258.

An Accurate Fiducial Marker for Aligning EMG signals with Swallow Onset. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023;2023:1-4. [PMID: 38082870 DOI: 10.1109/embc40787.2023.10340093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Swallowing involves the precise coordination of a large number of muscles. This coordination can be quantified non-invasively by electromyographic (EMG) time-series analysis of swallowing events. The temporal alignment of swallow events is critical for defining coordination patterns. Here, a new framework was developed to use the acoustic signal associated with the opening of the Eustachian tube as a fiducial marker to align EMG signals with swallowing. To investigate its accuracy, manometry, audio from the Eustachian tube, and EMG were simultaneously recorded from two participants while performing different swallowing maneuvers. Eustachian tube opening consistently occurred alongside EMG activations and within 0.025 ± 0.022 s of the gold standard manometry-determined functional swallowing onset. A comparison with two traditional EMG alignment methods based on the integrated and rectified EMG signals was then performed over eight participants. Discrepancies of between 0.2 to 0.3 s were found between the initiation of swallowing and the onset or peak EMG activity. Eustachian tube opening served as a more accurate fiducial marker for temporal data alignment, compared to the traditional EMG alignment methods that were based on EMG parameters.Clinical Relevance- The proposed method will allow EMG recordings to be directly associated with the functional onset of swallowing. This provides a more accurate foundation for time-series analysis of muscle coordination and thus the identification of EMG biomarkers associated with healthy and dysphagic swallowing.

Crosstalk in Facial EMG and Its Reduction Using ICA

There is ample evidence that electromyography (EMG) signals from the corrugator supercilii and zygomatic major muscles can provide valuable information for the assessment of subjective emotional experiences. Although previous research suggested that facial EMG data could be affected by crosstalk from adjacent facial muscles, it remains unproven whether such crosstalk occurs and, if so, how it can be reduced. To investigate this, we instructed participants (n = 29) to perform the facial actions of frowning, smiling, chewing, and speaking, in isolation and combination. During these actions, we measured facial EMG signals from the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles. We performed an independent component analysis (ICA) of the EMG data and removed crosstalk components. Speaking and chewing induced EMG activity in the masseter and suprahyoid muscles, as well as the zygomatic major muscle. The ICA-reconstructed EMG signals reduced the effects of speaking and chewing on zygomatic major activity, compared with the original signals. These data suggest that: (1) mouth actions could induce crosstalk in zygomatic major EMG signals, and (2) ICA can reduce the effects of such crosstalk.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

A robust HD-sEMG sensor suitable for convenient acquisition of muscle activity in clinical post-stroke dysphagia

Objective.A flexible high-density surface electromyography (HD-sEMG) sensor combined with an adaptive algorithm was used to collect and analyze the swallowing activities of patients with Post-stroke dysphagia.Approach.The electrode frame, modified electrode, and bonded substrate of the sensor were fabricated using a flexible printed circuit process, controlled drop coating, and molding, respectively. The adaptation algorithm was achieved by using Laplace and Teager-Kaiser energy operators to extract active segments, a cross-correlation coefficient matrix (CCCM) to evaluate synergy, and multi-frame real-time dynamic root mean square (RMS) to visualize spatiotemporal information to screen lesions and level of dysphagia. Finally, support vector machines (SVM) were adopted to explore the classification accuracy of sex, age, and lesion location with small sample sizes.Main results.The sensor not only has a basic low contact impedance (0.262 kΩ) and high signal-to-noise ratio (37.284 ± 1.088 dB) but also achieves other characteristics suitable for clinical applications, such as flexibility (747.67 kPa) and durability (1000 times) balance, simple operation (including initial, repeated, and replacement use), and low cost ($ 15.2). The three conclusions are as follows. CCCM can be used as a criterion for judging the unbalanced muscle region of the patient's neck and can accurately locate unbalanced muscles. The RMS cloud map provides the time consumption, swallowing times, and unbalanced areas. When the lesion location involves the left and right hemispheres simultaneously, it can be used as an evidence of relatively severely unbalanced areas. The classification accuracy of SVM in terms of sex, age, and lesion location was as high as 100%.Significance.The HD-sEMG sensor in this study and the adaptation algorithm will contribute to the establishment of a larger-scale database in the future to establish more detailed and accurate quantitative standards, which will be the basis for developing more optimized screening mechanisms and rehabilitation assessment methods.

Thin Liquid Bolus Volume Alters Pharyngeal Swallowing: Kinematic Analysis Using 3D Dynamic CT

The previous studies reported that different volumes of thick liquid had an impact on spatiotemporal characteristics and pharyngeal response of swallowing. However, the bolus flow and swallowing motion pattern were different between thick and thin liquids. The effects of thin bolus volume on pharyngeal swallowing, especially true vocal cord (TVC) closure is still unclear. This study assessed the temporal characteristics when swallowing different volumes of thin liquid to determine the mechanical adaptation using 320-row area detector computed tomography (320-ADCT) and investigated a change of swallowing physiology including laryngeal closure, particularly TVC closure. Fourteen healthy women (28-45 years) underwent 320-ADCT while swallowing of 3, 10, and 20 ml of thin liquid barium in 45° semi-reclining position. Kinematic analysis was performed for each swallow including temporal characteristic, structural movements while swallowing, and maximal cross-sectional area of the upper esophageal sphincter (UES) opening. Bolus head reached to pharynx and esophagus earlier in larger volume significantly, indicating faster bolus transport as volume increased. There were significant effects on swallowing mechanism revealing earlier TVC closure and UES opening with increasing volume. Maximum cross-sectional area of the UES opening was increased to accommodate a larger bolus. Differences in mechanical adaptation through bolus transit and motion of swallowing structures were detected across increasing volumes. These volume-dependent adaptations potentially reduce the risk of aspiration. Understanding the swallowing physiological changes as volume increased is helpful for diagnosis and treatment of dysphagia patients as well as outcomes of swallowing rehabilitation in clinical practice.

Directed Functional Coordination Analysis of Swallowing Muscles in Healthy and Dysphagic Subjects by Surface Electromyography

Swallowing is a complex sequence of highly regulated and coordinated skeletal and smooth muscle activity. Previous studies have attempted to determine the temporal relationship between the muscles to establish the activation sequence pattern, assessing functional muscle coordination with cross-correlation or coherence, which is seriously impaired by volume conduction. In the present work, we used conditional Granger causality from surface electromyography signals to analyse the directed functional coordination between different swallowing muscles in both healthy and dysphagic subjects ingesting saliva, water, and yoghurt boluses. In healthy individuals, both bilateral and ipsilateral muscles showed higher coupling strength than contralateral muscles. We also found a dominant downward direction in ipsilateral supra and infrahyoid muscles. In dysphagic subjects, we found a significantly higher right-to-left infrahyoid, right ipsilateral infra-to-suprahyoid, and left ipsilateral supra-to-infrahyoid interactions, in addition to significant differences in the left ipsilateral muscles between bolus types. Our results suggest that the functional coordination analysis of swallowing muscles contains relevant information on the swallowing process and possible dysfunctions associated with dysphagia, indicating that it could potentially be used to assess the progress of the disease or the effectiveness of rehabilitation therapies.

Fabrication of Skin-Mountable Flexible Sensor Patch for Monitoring of Swallowing Function

Swallowing is a critical function that enables humans to sustain life. When swallowing is compromised, the consequences can be devastating and include malnutrition, dehydration, respiratory compromise, and even death. Swallowing disorders (i.e., dysphagia) are very common in many disorders and diseases, such as stroke, ALS, Parkinson disease, and more, and in fact millions of people across the world are diagnosed with oropharyngeal swallowing disorders every year. Current rehabilitative interventions for dysphagia can be effective, but require daily performance of swallowing exercises that primarily rely on expensive biofeedback devices (e.g., oral manometers, electromyographic (EMG) devices, and endoscopic devices). These types of devices are often only available in medical facilities. However, it is not feasible or economically viable for patients to make multiple visits per day or week to a clinic to receive intensive treatment, especially given mobility limitations that many affected patients often experience. This can reduce treatment adherence and result in decreased rehabilitation potential, re-hospitalizations, and increased healthcare costs. To address this gap, we designed a novel specialized portable skin-mounted flexible sensor system that allows remote signal acquisition of swallowing-related signals. Herein, we report technical details for the fabrication of the skin-mounted flexible sensor patch that is tailored for the human submental (under the chin) area, enabling the continuous, reliable monitoring of both muscles' activity (i.e., EMG signals) and laryngeal movements during swallowing events. The sensor patch is wired to a portable reusable wireless (Bluetooth) unit compatible with smart watches, phones, and tablets for post-data analysis and reporting through a cloud server, which would potentially enable telemonitoring of patients with dysphagia.

Manual Therapy for Fibrosis-Related Late Effect Dysphagia in head and neck cancer survivors: the pilot MANTLE trial

INTRODUCTION

Late dysphagia that develops or persists years after head and neck cancer (HNC) is a disabling survivorship issue. Fibrosis is thought to stiffen connective tissues and compress peripheral nerve tracts, thereby contributing to diminished strength, flexibility, and in some cases denervation of swallowing muscles. Manual therapy (MT) is used in cancer survivors for pain and other indications, but it is unknown if increasing blood flow, flexibility and cervical range of motion (CROM) in the head and neck may improve late dysphagia.

METHODS AND ANALYSIS

Manual Therapy for Fibrosis-Related Late Effect Dysphagia (MANTLE) is a National Cancer Institute-funded prospective single-arm pilot trial evaluating the feasibility, safety and therapeutic potential of MT in patients with late dysphagia after radiotherapy (RT) for HNC. Disease-free survivors ≥2 years after curative-intent RT for HNC with at least moderate dysphagia and grade ≥2 Common Terminology Criteria for Adverse Events version 4.0 fibrosis are eligible. The target sample size is 24 participants who begin the MANTLE programme. MANTLE is delivered in 10 MT sessions over 6 weeks with an accompanying home exercise programme (HEP). Patients then transition to a 6-week post-washout period during which they complete the HEP and then return for a final post-washout evaluation. Feasibility (primary endpoint) and safety will be examined. Serial assessments include CROM, modified barium swallow studies, quantitative MRI, electromyography (optional) and patient-reported outcomes as secondary, tertiary and exploratory endpoints.

ETHICS AND DISSEMINATION

The research protocol and informed consent document was approved by the Institutional Review Board at the University of Texas MD Anderson Cancer Center. Findings will be disseminated through peer-reviewed publication that will be made publicly available on PubMed Central on acceptance for publication, in compliance with NIH public access policy.

TRIAL REGISTRATION NUMBER

NCT03612531.

Electromyographic activation patterns during swallowing in older adults

Age-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

Effect of Volitional Effort on Submental Surface Electromyographic Activity During Healthy Swallowing

The effortful swallowing technique aims to compensate for or rehabilitate impaired swallowing by using maximal volitional effort to behaviorally modify aspects of swallowing physiology. Given that swallowing is a submaximal task, swallowing at submaximal levels has recently been suggested as a more task-specific therapeutic technique. The aim of this study was to investigate differences in muscle activity during minimum, regular, and maximum effort swallowing of different boluses and across different ages, with the goal of characterizing the task specificity of minimum effort and maximum effort swallowing. Forty-three healthy adults (22 female) representing four age groups (20-39, 40-59, 60-79, and 80 + years) participated in the study. They were verbally cued to swallow saliva and 5 mL water boluses using participant-determined minimum, regular, and maximum levels of effort, in randomized order. sEMG peak amplitude and duration of each swallow were measured. Linear mixed effects analyses demonstrated that compared to regular effort swallowing, maximum effort swallowing resulted in increased sEMG amplitude (p < .001) and prolonged duration (p < .001), while minimum effort swallowing resulted in decreased amplitude (p < .001) but no significant difference in duration (p = .06). These effects occurred regardless of age or bolus type. Differences in sEMG activity were smaller between regular and minimum effort swallowing than regular and maximum effort swallowing. Both increasing and decreasing volitional efforts during swallowing translate to significant modulation of muscle activity. However, regular swallowing is more similar to minimal effort swallowing. Results reinforce the concept of swallowing as a submaximal task, and provide insight into the development of sEMG biofeedback techniques for rehabilitation.

Examining the Relationships Between Lingual Strength, Perihyoid Strength, and Swallowing Kinematics in Dysphagic Adults: A Retrospective Cross-Sectional Analysis

Purpose The aim of this study was to examine the relationships of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics and swallowing safety in a heterogenous group of dysphagic adults. Method A retrospective analysis was completed of videofluoroscopic swallow studies of consecutive dysphagic outpatient adults presenting to a tertiary swallowing center from January 1, 2015, to December 31, 2017. Videofluoroscopic swallow study records were included if containing displacement swallowing kinematics of a 20-ml single liquid swallow and clinical measures of anterior (L-MIPA) or posterior (L-MIPP) lingual maximal isometric press, saliva mean swallowing pressures (S-MSP), and/or open mouth-maximal isometric press (OM-MIP). Regression analyses were used to examine the relationships between clinical measures of lingual (L-MIPA, L-MIPP, S-MSP) and perihyoid (OM-MIP) strength and displacement swallowing kinematics, and binomial logistic regressions were used to examine the relationships between clinical measures of lingual and perihyoid strength and swallowing safety (Penetration-Aspiration Scale [PAS]). Results Multivariate regressions revealed significant relationships of L-MIPA, L-MIPP, S-MSP, and OM-MIP with group-level changes to the displacement swallowing kinematics. Univariate analyses revealed significant relationships of L-MIPA and L-MIPP with pharyngeal constriction ratio, maximal extent of upper esophageal segment opening, and PAS. Conclusions Weak relationships were identified of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics. These findings suggest that clinical measures of lingual and perihyoid strength do not fully explain impairments in swallowing kinematics across a heterogenous group of dysphagic patients. Weak-to-moderate relationships were identified between clinical measures of lingual strength and PAS, suggesting that they may have value in predicting functional measures of swallowing safety. Further research is needed to examine how findings may differ between specific patient populations.

Validation of a Novel Wearable Electromyography Patch for Monitoring Submental Muscle Activity During Swallowing: A Randomized Crossover Trial

Purpose Surface electromyography (sEMG) is often used for biofeedback during swallowing rehabilitation. However, commercially available sEMG electrodes are not optimized for the head and neck area, have rigid form, and are mostly available in large medical centers. We developed an ultrathin, soft, and flexible sEMG patch, specifically designed to conform to the submental anatomy and which will be ultimately incorporated into a telehealth system. To validate this first-generation sEMG patch, we compared its safety, efficiency, and signal quality in monitoring submental muscle activity with that of widely used conventional sEMG electrodes. Method A randomized crossover design was used to compare the experimental sEMG patch with conventional (snap-on) sEMG electrodes. Participants completed the same experimental protocol with both electrodes in counterbalanced order. Swallow trials included five trials of 5- and 10-ml water. Comparisons were made on (a) signal-related factors: signal-to-noise ratio (SNR), baseline amplitude, normalized mean amplitude, and sEMG burst duration and (b) safety/preclinical factors: safety/adverse effects, efficiency of electrode placement, and satisfaction/comfort. Noninferiority and equivalence tests were used to examine signal-related factors. Paired t tests and descriptive statistics were used to examine safety/preclinical factors. Results Forty healthy adults participated (24 women, M _age = 67.5 years). Signal-related factors: SNR of the experimental patch was not inferior to the SNR of the conventional electrodes (p < .0056). Similarly, baseline amplitude obtained with the experimental patch was not inferior to that obtained with conventional electrodes (p < .0001). Finally, normalized amplitude values were equivalent across swallows (5 ml: p < .025; 10 ml: p < .0012), and sEMG burst duration was also equivalent (5 ml: p < .0001; 10 ml: p < .0001). Safety/preclinical factors: The experimental patch resulted in fewer mild adverse effects. Participant satisfaction was higher with the experimental patch (p = .0476, d = 0.226). Conclusions Our new wearable sEMG patch is equivalent with widely used conventional sEMG electrodes in terms of technical performance. In addition, our patch is safe, and healthy older adults are satisfied with it. With lessons learned from the current COVID-19 pandemic, efforts to develop optimal swallowing telerehabilitation devices are more urgent than ever. Upon further validation, this new technology has the potential to improve rehabilitation and telerehabilitation efforts for patients with dysphagia. Supplemental Material https://doi.org/10.23641/asha.12915509.

Detection of swallowing disorders using a multiple channel surface electromyography sheet: A preliminary study

Background/purpose

We invented a sensor sheet with multiple electromyogram electrodes, which can be easily attached to the front of the neck, to evaluate surface electromyograms (sEMG) during swallowing function. In this paper, we evaluated sEMG in healthy volunteers and dysphagia patients using the sensor sheet and discussed its potential to evaluate swallowing function.

Materials and methods

Ten healthy volunteers (age, 29.5 ± 3.9 years) and 18 clinically diagnosed dysphagia patients (age, 67.8 ± 12.1 years) were included. The sensor sheet had four pairs of electrodes, and sEMG at the suprahyoid muscles (positions A and B) and the infrahyoid muscles (positions C and D) were recorded while swallowing water, thickened water, yogurt, and jelly; sEMG findings were compared between these positions.

Results

Significant differences in the duration of muscle activity was observed when swallowing yogurt at position D and when swallowing jelly, thickened water, and water at position B (Mann–Whitney U test, p < 0.05). In healthy volunteers, muscle activation typically began from positions A or B to position D, whereas in dysphagia patients, it sometimes began from position D.

Conclusion

There were significant differences in duration and sequence patterns of four sEMG activities between healthy young volunteers and dysphagia patients in the assessment using the sensor sheet, although some technical and scientific problems remained unresolved. These results indicate that swallowing function could be evaluated using the sensor sheet.

Prospective Analysis of the Swallowing Reflex After Sagittal Split Osteotomy: Comparison with Normal Volunteers

The aim of this study was electromyographic description of changes in swallowing before and after bilateral sagittal split ramus osteotomy. In this prospective study, twenty-eight patients were divided into 3 groups according to the occlusion pattern: Group I (Angle Class III), Group II (Angle Class II), and Control (Class I). Serial cone-beam computed tomography analyses and electromyographic data were collected preoperatively, 1st and 6th months after setback surgery in Group I, and advancement surgery in Group II. Swallowing reflex with 3-20 ml water bolus were studied. Patients were further divided into two subgroups according to the magnitude of relapse. The mean setback of the mandible was 4.62 ± 1.92 mm in Group I, and the mean advancement was 4.19 ± 2.00 mm in Group II. Mandibular relapse rate was 17.40%. Oral preparation phase shortened after surgery in both study groups. Two subjects in Group II and one in Group I had piecemeal deglutition, and two of them became normal postoperatively. Most of the swallowing durations of the relapsed cases were longer than those of stabilized patients. Important clinical considerations are as follows: the oral preparation period becomes shorter after surgery; piecemeal deglutition may disappear after treatment; and individuals with a longer oral period and piecemeal deglutition may have increased tendency to skeletal relapse. This multidisciplinary study enhances our understanding of the adaptive response to the swallowing reflex after orthognathic surgery and provides novel insight into the association between the submental muscle activity and relapse in orthognathic patients.

Flexible submental sensor patch with remote monitoring controls for management of oropharyngeal swallowing disorders

Successful rehabilitation of oropharyngeal swallowing disorders (i.e., dysphagia) requires frequent performance of head/neck exercises that primarily rely on expensive biofeedback devices, often only available in large medical centers. This directly affects treatment compliance and outcomes, and highlights the need to develop a portable and inexpensive remote monitoring system for the telerehabilitation of dysphagia. Here, we present the development and preliminarily validation of a skin-mountable sensor patch that can fit on the curvature of the submental (under the chin) area noninvasively and provide simultaneous remote monitoring of muscle activity and laryngeal movement during swallowing tasks and maneuvers. This sensor patch incorporates an optimal design that allows for the accurate recording of submental muscle activity during swallowing and is characterized by ease of use, accessibility, reusability, and cost-effectiveness. Preliminary studies on a patient with Parkinson's disease and dysphagia, and on a healthy control participant demonstrate the feasibility and effectiveness of this system.

Neuromuscular Electrical Stimulation Plus Rehabilitative Exercise as a Treatment for Dysphagia in Stroke and Non-Stroke Patients in an NHS Setting: Feasibility and Outcomes

Dysphagia is a debilitating condition with significant consequences in terms of physical and mental health. This study demonstrates that it is feasible to provide an intensive therapy program combining neuromuscular electrical stimulation (NMES) with exercise against resistance in the treatment of dysphagia in a public healthcare setting. Thirty-one patients (17 stroke, 14 non-stroke) who experienced dysphagia with reduced laryngeal elevation completed the therapy program. After checking the data sets for comparability, it was deemed appropriate for the outcome data from these patients to be combined with that of 12 stroke patients previously reported to enable statistical analysis on a larger data set (n = 43). A repeated-measures ANOVA revealed a statistically significant increase in amount and variety of food a patient was able to take orally (FOIS) following completion of treatment (p < 0.001). There was no significant between-subject effect of stroke status (p = 0.43), or interaction between treatment and stroke status (p = 0.68). There was a significant improvement in secondary outcome measures of swallow safety with fluids (PAS) (p < 0.001) and swallow-related quality of life (Swal-Qol (p < 0.001). These findings indicate that the therapy program may be associated with reduced impairment in a subset of patients with dysphagia resulting from stroke and non-stroke atiologies, and the data will inform the design of future research to address unanswered questions.

Functional Anatomy Underlying Pharyngeal Swallowing Mechanics and Swallowing Performance Goals

Purpose

Rehabilitation of pharyngeal swallowing dysfunction requires a thorough understanding of the functional anatomy underlying the performance goals of pharyngeal swallowing. These goals include the safe and efficient transfer of a bolus through the hypopharynx into the esophagus. Penetration or aspiration of a bolus threatens swallowing safety. Bolus residue indicates swallowing inefficiency. Several primary mechanics, or elements of the swallowing mechanism, underlie these performance goals, with some elements contributing to both goals. These primary mechanics include velopharyngeal port closure, hyoid movement, laryngeal elevation, pharyngeal shortening, tongue base retraction, and pharyngeal constriction. Each element of the swallowing mechanism is under neuromuscular control and is therefore, in principle, a potential target for rehabilitation. Secondary mechanics of pharyngeal swallowing, those movements dependent on primary mechanics, include opening the upper esophageal sphincter and epiglottic inversion.

Conclusion

Understanding the functional anatomy of pharyngeal swallowing underlying swallowing performance goals will facilitate anatomically informed critical thinking in the rehabilitation of pharyngeal swallowing dysfunction.

Effect of an indwelling nasogastric tube on swallowing function in elderly post-stroke dysphagia patients with long-term nasal feeding

BACKGROUND

In clinical practice, a large number of post-stroke survivors require nasogastric tube (NGT) placement and nasal feeding for a relatively long period. However, its impact on the swallowing function remains largely unknown. This study examines the impact of prolonged placement of an NGT on the swallowing function of elderly post-stroke patients.

METHODS

The participants of this study were 30 elderly post-stroke patients who had been using an NGT for more than 2 months. A videofluoroscopic swallowing study (VFSS) was performed before and 5 h after removal of the NGT. The following parameters were analyzed and compared, the functional dysphagia scale (FDS), residue in the valleculae, residue in the pyriform sinuses, and the penetration-aspiration scale (PAS). In addition, prior to the VFSS, the pharynx and larynx were examined using a fiberoptic laryngoscope.

RESULTS

Significant differences were observed between the total scores of the FDS, pharyngeal transit times (PTTs), the residue in the valleculae, and the residue in the pyriform sinuses before and after the NGT removal, suggesting an improved swallowing function following the removal of the NGT. A significantly lower penetration-aspiration degree was found after removing the NGT compared with that before its removal. In addition, examinations using the fiberoptic laryngoscope showed that laryngopharyngeal edema was present in three quarters of the patients.

CONCLUSIONS

Our results demonstrate that prolonged placement of the NGT had a negative impact on the swallowing function of elderly post-stroke dysphagia patients, mainly on the pharyngeal phase.

Open Mouth-Maximal Isometric Press: Development and Norms for Clinical Swallowing Evaluations and Treatment

Purpose The aims of this study were to (a) describe the development and utility of the Open Mouth-Maximal Isometric Press (OM-MIP), a tool designed for the quantitative assessment of suprahyoid-infrahyoid muscle strength; (b) examine the effects of age and sex on the OM-MIP; and (c) establish age- and sex-based OM-MIP norms. Method Two hundred sixteen healthy male and female volunteers were recruited. Participants performed the OM-MIP, and the maximum of 3 trials that were within 10% of each other was recorded. Rest between each trial was allowed to avoid fatigue. Multiple regression examined the influence of age and sex on the OM-MIP. Descriptive statistics outlined normative OM-MIP values for young adult (aged 18-39 years), middle-aged adult (aged 40-59 years), old adult (aged 60-79 years), and very old adult (aged ≥ 80 years) men and women. Two-way analysis of variance determined if normative data differed significantly between the age and sex groups. Results Age and sex significantly influenced the OM-MIP, although no significant interaction effect was identified. Women had lower mean OM-MIPs when compared with men ( p < .0005), and very old adults had lower mean OM-MIPs when compared with young ( p = .001), middle-aged ( p < .0005), and old ( p = .013) adults. Conclusions This study establishes age- and sex-based OM-MIP norms and outlines its potential utility during clinical swallowing evaluations and treatment. By providing these norms, clinicians can begin to quantitatively measure suprahyoid and infrahyoid strength, individualize resistance training programs to patients' OM-MIP 1 repetition maximum, and track strength changes over time in response to therapeutic interventions.

The Contribution of Surface Electromyographic Assessment for Defining the Stage of Peripheral Facial Paralysis: Flaccid or Sequelae Stage

Introduction  Surface electromyographic activity may not be symmetric, even in subjects with no facial paralysis history.

Objective  To evaluate the contribution of the index of electromyographic (IEMG) activity in the identification of the two extremes of the facial paralysis course.

Methods  Thirty-four subjects with unilateral peripheral facial paralysis were selected. A control group was composed of volunteers without a history of facial paralysis. The electromyographic assessment of the facial muscle was performed by placing surface electrodes during movements of the forehead, eyes and lips using MIOTEC equipment, such as the MIOTOOL (Miotec, Porto Alegre, Brazil) software. The electromyographic activity was also recorded in other channels during the primary activity to identify the presence of synkinesis. The statistical analysis was performed using the Statistical Package for Social Sciences for Macintosh (SPSS Inc, Chicago, IL, USA). The IEMG activity was obtained from the division of the electromyographic activity root mean square (RMS) values on both sides.

Results  There was a statistically significant difference among the groups in all the analyzed indexes. The ocular-oral synkinesis in all patients must be correctly identified (with 100% sensitivity and specificity) using an IEMG activity of 1.62 as a cutoff point. The oral-ocular synkinesis must be correctly identified (93.3% sensitivity and 95.9% specificity) using the IEMG activity of 1.79 as a cutoff point.

Conclusion  The IEMG activity is below the normal scores in patients in the flaccid stage, whereas patients in the sequelae stage can either show normal values or values above or below the normal scores. The IEMG activity was shown to have high sensitivity and specificity in the identification of synkinesis.

Characteristics of Cricopharyngeal Dysphagia After Ischemic Stroke

Objective

To evaluate the characteristics of cricopharyngeal dysfunction (CPD), the frequency, and correlation with a brain lesion in patients with first-ever ischemic stroke, and to provide basic data for developing a therapeutic protocol for dysphagia management.

Methods

We retrospectively reviewed the medical records of a series of subjects post-stroke who underwent a videofluoroscopic swallowing study (VFSS) from January 2009 to December 2015. VFSS images were recorded on videotape and analyzed. CPD was defined as the retention of more than 25% of residue in the pyriform sinus after swallowing. The location of the brain lesion was assessed using magnetic resonance imaging.

Results

Among the 262 dysphagic patients with first-ever ischemic stroke, 15 (5.7%) showed CPD on the VFSS. Patients with an infratentorial lesion had a significantly higher proportion of CPD than those with a supratentorial lesion (p=0.003), and lateral medullary infarction was identified as the single independent predictor of CPD (multivariable analysis: odds ratio=19.417; confidence interval, 5.560–67.804; p<0.0001). Compared to patients without CPD, those with CPD had a significantly prolonged pharyngeal transit time, lower laryngeal elevation, and a higher pharyngeal constriction ratio and functional dysphagia scale score.

Conclusion

Overall, the results support the notion that an impaired upper esopharyngeal opening is likely related to the specific locations of brain lesions. The association of CPD with lateral medullary infarction can be explained based on the regulation of the pharyngolaryngeal motor system by the motor neurons present in the dorsal nucleus ambiguus. Overall, the results reveal the relation between CPD and the problems in the pharyngeal phase as well as the severity of dysphagia.

Effect of bolus volume and flow time on temporospatial coordination in oropharyngeal pressure production in healthy subjects

The effects of bolus volume and flow time on the sequential coordination of tongue pressure (TP) and pharyngeal pressure (PP), which are important in the biomechanics of swallowing, are unclear. In this study, we measured TP and PP simultaneously in 10 healthy adults at multiple points during dry swallowing and the swallowing of 5 ml and 15 ml of liquids with different viscosities, and investigated changes in the timing of the onset, peak, and offset of these pressures. TP was measured using a sensor sheet system with five measuring points on the hard palate, and PP was measured using a manometry catheter with four measuring points. The order and correlations of sequential events, such as onset, peak, and offset times of pressure production, at each pressure measuring point were analyzed on the synchronized waveforms. We found that the differences between the TP and PP onset times decreased when the bolus volume was larger. The change in bolus volume had very little effect on peak time or offset time. The flow time of the bolus affected the appearance of onset and peak time for both TP and PP. A time difference between TP and PP emerged as the flow time increased, with TP starting to appear before PP. This may be the first detailed analysis of pressure-flow dynamics that treats the mouth and pharynx as a single functional unit. We believe that our analysis is an important step toward extending future research to include a wider range of age groups and dysphagia patients.

Evaluation of normal swallowing functions by using dynamic high-density surface electromyography maps

BACKGROUND

Swallowing is a continuous process with substantive interdependencies among different muscles, and it plays a significant role in our daily life. The aim of this study was to propose a novel technique based on high-density surface electromyography (HD sEMG) for the evaluation of normal swallowing functions.

METHODS

A total of 96 electrodes were placed on the front neck to acquire myoelectric signals from 12 healthy subjects while they were performing different swallowing tasks. HD sEMG energy maps were constructed based on the root mean square values to visualize muscular activities during swallowing. The effects of different volumes, viscosities, and head postures on the normal swallowing process were systemically investigated by using the energy maps.

RESULTS

The results showed that the HD sEMG energy maps could provide detailed spatial and temporal properties of the muscle electrical activity, and visualize the muscle contractions that closely related to the swallowing function. The energy maps also showed that the swallowing time and effort was also explicitly affected by the volume and viscosity of the bolus. The concentration of the muscular activities shifted to the opposite side when the subjects turned their head to either side.

CONCLUSIONS

The proposed method could provide an alternative method to physiologically evaluate the dynamic characteristics of normal swallowing and had the advantage of providing a full picture of how different muscle activities cooperate in time and location. The findings from this study suggested that the HD sEMG technique might be a useful tool for fast screening and objective assessment of swallowing disorders or dysphagia.

The importance of the reproducibility of oropharyngeal swallowing in amyotrophic lateral sclerosis. An electrophysiological study

OBJECTIVE

To investigate electrophysiologically the reproducibility of oropharyngeal swallowing in patients with ALS.

METHODS

We enrolled 26 ALS patients, both with and without clinical signs of dysphagia, and 30 age-matched controls. The reproducibility of the electrophysiological signals related to the oral phase (electromyographic activity of the submental/suprahyoid muscles) and the pharyngeal phase (laryngeal-pharyngeal mechanogram) of swallowing across repeated swallows was assessed. To do this we computed two similarity indexes (SI) by using previously described mathematical algorithms.

RESULTS

The reproducibility of oropharyngeal swallowing was significantly reduced both in patients with and in those without clinical signs of dysphagia, with more marked alterations being detected in the dysphagic group. The SI of both phases of swallowing, oral and pharyngeal, correlated significantly with dysphagia severity and disease severity.

CONCLUSIONS

In ALS different pathophysiological mechanisms can alter the stereotyped motor behaviors underlying normal swallowing, thus reducing the reproducibility of the swallowing act. A decrease in swallowing reproducibility could be a preclinical sign of dysphagia and, beyond a certain threshold, a pathological hallmark of oropharyngeal dysphagia.

SIGNIFICANCE

Electrophysiological assessment is a simple and useful tool for the early detection of swallowing abnormalities, and for the management of overt dysphagia in ALS.

Expiratory muscle strength training evaluated with simultaneous high-resolution manometry and electromyography

OBJECTIVE

To examine feasibility of a simultaneous high-resolution pharyngeal manometry (HRM) and electromyography (EMG) experimental paradigm to detect swallowing-related patterns of palatal, laryngeal, and pharyngeal muscle activity during expiratory training.

STUDY DESIGN

Technical report.

METHODS

Simultaneous HRM, surface submental, and intramuscular EMG were acquired in two healthy participants during five tasks: 10-cc water swallow, maximum expiratory pressure (MEP) testing, and expiratory muscle strength training (EMST) at three pressure levels (sham, 50%, and 75% MEP).

RESULTS

Experimental conditions were feasible. Velopharyngeal closing pressure, palate EMG activity, and pharyngeal EMG activity increased as expiratory load increased. In contrast, thyroarytenoid EMG activity was low during the expiratory task, consistent with glottic opening during exhalation. Submental EMG patterns were more variable during expiratory tasks. Intraluminal air pressures recorded with HRM were correlated with measured expiratory pressures and target valve-opening pressures of the EMST device.

CONCLUSION

Results suggest that a simultaneous HRM/EMG/EMST paradigm may be used to detect previously unquantified swallowing-related muscle activity during EMST, particularly in the palate and pharynx. Our approach and initial findings will be helpful to guide future hypothesis-driven studies and may enable investigators to evaluate other muscle groups active during these tasks. Defining mechanisms of action is a critical next step toward refining therapeutic algorithms using EMST and other targeted treatments for populations with dysphagia and airway disorders.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:797-804, 2017.

Contribuições da eletromiografia de agulha para o estudo da deglutição em seres humanos

RESUMO A Eletromiografia intramuscular é realizada pelo médico, a partir da fixação de eletrodos de agulha ou de fio fino para o estudo de músculos isolados ou músculos profundos. Esse estudo tem como objetivo identificar e descrever as contribuições da eletromiografia intramuscular, para a avaliação da deglutição em seres humanos. A busca, realizada no período entre abril e março de 2015, nos bancos de dados da PUBMED, BIREME E BANCO DE TESES DA CAPES, resultaram em 21 referências, das quais, apenas sete se enquadraram nos critérios de inclusão. Os artigos selecionados trazem contribuições importantes para o entendimento do comportamento eletrofisiológico e eletrofisiopatológico durante a deglutição e acredita-se que a escassez de estudos utilizando essa ferramenta em seres humanos deva-se ao incômodo e riscos causados pela introdução da agulha no ventre muscular e talvez a introdução de um fio fino (fine wire ou cooper wire), seja mais interesante para o auxílio diagnóstico de denervações e transtornos neuromusculares que comprometam a deglutição, pela possibilidade de reduzir drasticamente o incômodo causado pela agulha.

Identification of the most significant electrode positions in electromyographic evaluation of swallowing-related movements in humans

Surface electromyography (sEMG) is a well-established procedure for recording swallowing-related muscle activities. Because the use of a large number of sEMG channels is time consuming and technically sophisticated, the aim of this study was to identify the most significant electrode positions associated with oropharyngeal swallowing activities. Healthy subjects (N = 16) were tested with a total of 42 channels placed in M. masseter, M. orbicularis oris, submental and paralaryngeal regions. Each test subject swallowed 10 ml of water five times. After having identified 16 optimal electrode positions, that is, positions with the strongest signals quantified by the highest integral values, differences to 26 other ones were determined by a Mann-Whitney U test. Kruskal-Wallis H test was utilized for the analysis of differences between single subjects, subject subgroups, and single electrode positions. Factors associated with sEMG signals were examined in a linear regression. Sixteen electrode positions were chosen by a simple ranking of integral values. These positions delivered significantly higher signals than the other 26 positions. Differences between single electrode positions and between test subjects were also significant. Sixteen most significant positions were identified which represent swallowing-related muscle potentials in healthy subjects.

Anatomical Directional Dissimilarities in Tri-axial Swallowing Accelerometry Signals

Swallowing accelerometry is a noninvasive approach currently under consideration as an instrumental screening test for swallowing difficulties, with most current studies focusing on the swallowing vibrations in the anterior-posterior (A-P) and superior-inferior (S-I) directions. However, the displacement of the hyolaryngeal structure during the act of swallowing in patients with dysphagia involves declination of the medial-lateral (M-L), which suggests that the swallowing vibrations in the M-L direction have the ability to reveal additional details about the swallowing function. With this motivation, we performed a broad comparison of the swallowing vibrations in all three anatomical directions. Tri-axial swallowing accelerometry signals were concurrently collected from 72 dysphagic patients undergoing videofluoroscopic evaluation of swallowing (mean age: 63.94 ± 12.58 years period). Participants swallowed one or more thickened liquids with different consistencies including thin-thick liquids, nectar-thick liquids, and pudding-thick liquids with either a comfortable self-selected volume from a cup or a controlled volume by the examiner from a 5-ml spoon. Swallows were grouped based on the viscosity of swallows and the participant's stroke history. Then, a comprehensive set of features was extracted in multiple signal domains from 881 swallows. The results highlighted inter-axis dissimilarities among tri-axial swallowing vibrations including the extent of variability in the amplitude of signals, the degree of predictability of signals, and the extent of disordered behavior of signals in time-frequency domain. First, the upward movement of the hyolaryngeal structure, representing the S-I signals, were actually more variable in amplitude and showed less predictable behavior than the sideways and forward movements, representing the A-P and M-L signals, during swallowing. Second, the S-I signals, which represent the upward movement of the hyolaryngeal structure, behaved more disordered in the time-frequency domain than the sideways movement, M-L signals, in all groups of study except for the pudding swallows in the stroke group. Third, considering the viscosity and the participant's pathology, thin liquid swallows in the nonstroke group presented the most directional differences among all groups of study. In summary, despite some directional dissimilarities, M-L axis accelerometry characteristics are similar to those of the two other axes. This indicates that M-L axis characteristics, which cannot be observed in videofluoroscopic images, can be adequately derived from the A-P and S-I axes.

Evaluating the Training Effects of Two Swallowing Rehabilitation Therapies Using Surface Electromyography--Chin Tuck Against Resistance (CTAR) Exercise and the Shaker Exercise

In this study, the efficacy of two dysphagia interventions, the Chin Tuck against Resistance (CTAR) and Shaker exercises, were evaluated based on two principles in exercise science-muscle-specificity and training intensity. Both exercises were developed to strengthen the suprahyoid muscles, whose contractions facilitate the opening of the upper esophageal sphincter, thereby improving bolus transfer. Thirty-nine healthy adults performed two trials of both exercises in counter-balanced order. Surface electromyography (sEMG) recordings were simultaneously collected from suprahyoid muscle group and sternocleidomastoid muscle during the exercises. Converging results using sEMG amplitude analyses suggested that the CTAR was more specific in targeting the suprahyoid muscles than the Shaker exercise. Fatigue analyses on sEMG signals further indicated that the suprahyoid muscle group were equally or significantly fatigued (depending on metric), when participants carried out CTAR compared to the Shaker exercise. Importantly, unlike during Shaker exercise, the sternocleidomastoid muscles were significantly less activated and fatigued during CTAR. Lowering the chin against resistance is therefore sufficiently specific and intense to fatigue the suprahyoid muscles.

Cross-activation and detraining effects of tongue exercise in aged rats

Voice and swallowing deficits can occur with aging. Tongue exercise paired with a swallow may be used to treat swallowing disorders, but may also benefit vocal function due to cross-system activation effects. It is unknown how exercise-based neuroplasticity contributes to behavior and maintenance following treatment. Eighty rats were used to examine behavioral parameters and changes in neurotrophins after tongue exercise paired with a swallow. Tongue forces and ultrasonic vocalizations were recorded before and after training/detraining in young and old rats. Tissue was analyzed for neurotrophin content. Results showed tongue exercise paired with a swallow was associated with increased tongue forces at all ages. Gains diminished after detraining in old rats. Age-related changes in vocalizations, neurotrophin 4 (NT4), and brain derived neurotrophic factor (BDNF) were found. Minimal cross-system activation effects were observed. Neuroplastic benefits were demonstrated with exercise in old rats through behavioral improvements and up-regulation of BDNF in the hypoglossal nucleus. Tongue exercise paired with a swallow should be developed, studied, and optimized in human clinical research to treat swallowing and voice disorders in elderly people.

The Effects of the VFSS Timing After Nasogastric Tube Removal on Swallowing Function of the Patients With Dysphagia

OBJECTIVE

To evaluate the effects of the videofluoroscopic swallowing study (VFSS) timing after the nasogastric tube (NGT) removal on swallowing function of the patients with dysphagia.

METHODS

This study was conducted on 40 NGT-fed patients with dysphagia. To assess the patients' swallowing function, VFSS was performed twice using a 5-mL 35% diluted barium solution. For the initial examination, VFSS was performed immediately after the NGT removal (VFSS 1). For the second examination, VFSS was performed five hours after the NGT removal (VFSS 2). We used the functional dysphagia scale (FDS) to assess swallowing function. In the FDS, a significant difference in the four items in the oral phase, seven items in the pharyngeal phase, and total scores were assessed (p<0.05). We also used modified penetration-aspiration scale (mPAS) to compare the two examinations (p<0.05).

RESULTS

A paired t-test was performed to confirm the statistical significance of the two examinations (p<0.05). The overall swallowing function was assessed as better in VFSS 2 than in VFSS 1. In the FDS, significant differences in the residue in valleculae (p=0.002), the residue in pyriform sinuses (p=0.001), the coating of pharyngeal wall after swallow (p=0.001), and the total scores (p<0.001) were found between the two examinations. Also, in the mPAS that assessed the degree of penetration-aspiration, a significant difference was found between the two examinations (p<0.001).

CONCLUSION

The results of this study confirmed that the timing of the VFSS after the NGT removal affects the swallowing function. Thus, to accurately assess the swallowing function, VFSS must be performed in NGT-fed patients after they have rested for a certain period following the removal of their NGT.

Electrophysiological Investigations of Shape and Reproducibility of Oropharyngeal Swallowing: Interaction with Bolus Volume and Age

Electrophysiological assessment provides valuable information on physiological and pathophysiological characteristics of human swallowing. Here, new electrophysiological measures for the evaluation of oropharyngeal swallowing were assessed: (1) the activation pattern of the submental/suprahyoid EMG activity (SHEMG); (2) the reproducibility of the oral and pharyngeal phases of swallowing, by calculating the similarity index (SI) of the SHEMG (SI-SHEMG) and of the laryngeal-pharyngeal mechanogram (SI-LPM) during repeated swallows; and (3) kinesiological measures related to the LPM. An electrophysiological-mechanical method for measuring the activation pattern of the SHEMG, the SI-SHEMG, and the SI-LPM, and maximal LPM velocity and acceleration during swallowing was applied in 65 healthy subjects divided into three age groups (18-39, 40-59, 60 years or over). All the measures were assessed during three trials of eight consecutive swallows of different liquid bolus volumes (3, 12, and 20 ml). A high overall reproducibility of oropharyngeal swallowing in healthy humans was recorded. However, while values of SI-SHEMG were similar in all the age groups, the SI-LPM was found to fall significantly in the older age group. Both the SI-SHEMG and the SI-LPM were found to fall with increasing bolus volumes. The activation pattern of the SHEMG and the LPM kinesiological measures were differently modified by bolus volume and age in the older subjects with respect to the others. We describe a new approach to the electrophysiological study of swallowing based on computed semi-automatic analyses. Our findings provide insight into some previously uninvestigated aspects of oropharyngeal swallowing physiology, considered in relation to bolus volume and age. The new electrophysiological measures here described could prove useful in the clinical setting, as it is likely that they could be differently affected in patients with different kinds of dysphagia.

Role of the retrotrapezoid nucleus/parafacial respiratory group in coughing and swallowing in guinea pigs

The retrotrapezoid/parafacial respiratory group (RTN/pFRG) located ventral to the facial nucleus plays a key role in regulating breathing, especially enhanced expiratory activity during hypercapnic conditions. To clarify the roles of the RTN/pFRG region in evoking coughing, during which reflexive enhanced expiration is produced, and in swallowing, during which the expiratory activity is consistently halted, we recorded extracellular activity from RTN/pFRG neurons during these fictive behaviors in decerebrate, paralyzed, and artificially ventilated guinea pigs. The activity of the majority of recorded respiratory neurons was changed in synchrony with coughing and swallowing. To further evaluate the contribution of RTN/pFRG neurons to these nonrespiratory behaviors, the motor output patterns during breathing, coughing, and swallowing were compared before and after brain stem transection at the caudal margin of RTN/pFRG region. In addition, the effects of transection at its rostral margin were also investigated to evaluate pontine contribution to these behaviors. During respiration, transection at the rostral margin attenuated the postinspiratory activity of the recurrent laryngeal nerve. Meanwhile, the late expiratory activity of the abdominal nerve was abolished after caudal transection. The caudal transection also decreased the amplitude of the coughing-related abdominal nerve discharge but did not abolish the activity. Swallowing could be elicited even after the caudal end transection. These findings raise the prospect that the RTN/pFRG contributes to expiratory regulation during normal respiration, although this region is not an essential element of the neuronal networks involved in coughing and swallowing.

Submental Muscle Activity is Delayed and Shortened During Swallowing Following Stroke

OBJECTIVE

To evaluate the activities of the submental muscles using surface electromyography (sEMG) in patients presenting with dysphagia secondary to middle cerebral artery (MCA) infarction, and to compare the results with those in healthy volunteers.

DESIGN

Retrospective study design.

SETTING

A dysphagia clinic at a tertiary care university hospital.

PARTICIPANTS

Twenty-one patients presenting with dysphagia after unilateral MCA infarction were recruited into the study within 2 months of stroke onset. To serve as a control group, 13 healthy volunteers were enrolled.

MAIN OUTCOME MEASURES

The primary sEMG parameters were swallowing onset, pretrigger duration, swallowing duration, and swallowing amplitude. Swallowing functional outcome was evaluated using the Videofluoroscopic Dysphagia Scale and the American Speech-Language-Hearing Association National Outcome Measurement System.

RESULTS

Patients with MCA infarction demonstrated significantly delayed swallowing onset (P < .001) and shorter swallowing duration (P = .003) compared with the controls. Duration from the start of sEMG activity and actual laryngeal elevation also was delayed in the patient group (P = .042). At a cut-off point of 0.13 seconds for swallowing onset, sensitivity was 85.7% and specificity was 69.2%. For swallowing duration, sensitivity was 84.6% and specificity was 66.7% with 1.05 seconds as the cut-off point.

CONCLUSIONS

Patients with MCA infarction showed not only delayed swallowing onset and pretrigger duration, but also shorter duration of sEMG activity compared with those in healthy volunteers. Our results suggest that dysphagia after stroke might be further compromised by delayed laryngeal response especially after the start of suprahyoid muscle activity, which represents impaired laryngeal protection mechanism.

Implementation of high-resolution manometry in the clinical practice of speech language pathology

Visual imaging modalities, videofluoroscopic swallow study (VFSS) and fiberoptic endoscopic evaluation of swallow, for assessment of oropharyngeal dysphagia have been part of the speech language pathologist's (SLPs) armamentarium for the diagnosis and treatment of dysphagia for decades. Recently, the addition of high-resolution manometry (HRM) has enabled the SLP to evaluate pharyngeal pressures and upper esophageal sphincter relaxation. Taken together, the use of visual imaging modalities with HRM can improve interpretation of swallowing physiology and facilitate more effective treatment planning. The goal of this article is to describe a clinical paradigm using HRM as an adjunct to VFSS, by the SLP, in the assessment of complex dysphagia. Moreover, in three cases described, the value of manometric measurements in elucidating swallowing imaging studies and documenting physiologic change in response to treatment is highlighted. As technology in this area is evolving, so will the clinical use of HRM by the SLP. Limitations of current HRM systems and applications are discussed.