An electrophysiological investigation of deglutition in man

Electrokinesiographic Study of Oropharyngeal Swallowing in Neurogenic Dysphagia

Electrokinesiographic study of swallowing (EKSS) can be useful for the assessment of patients with suspected or overt neurogenic dysphagia. EKSS consists of multichannel recording of the electromyographic (EMG) activity of the suprahyoid/submental muscle complex (SHEMG), the EMG activity of the cricopharyngeal muscle (CPEMG), and the laryngopharyngeal mechanogram (LPM). The LPM is an expression of the mechanical changes that the laryngopharyngeal structures undergo during the pharyngeal phase of swallowing. This method allows detailed evaluation of the magnitude, duration and temporal relations of the different events that characterize oropharyngeal swallowing, and thus in-depth exploration both of physiological deglutition mechanisms and of pathophysiological features of swallowing in neurogenic dysphagia. Furthermore, EKSS can guide dysphagia treatment strategies, allowing identification of optimal solutions for single patients. For instance, CPEMG recording can identify incomplete or absent relaxation of the upper esophageal sphincter during the pharyngeal phase of swallowing, thus suggesting a therapeutic approach based on botulinum toxin injection into the cricopharyngeal muscle. More recently, the 'shape' of SHEMG and the reproducibility of both SHEMG and LPM over repeated swallowing acts have been implemented as novel electrokinesiographic parameters. These measures could be valuable for straightforward non-invasive investigation of dysphagia severity and response to dysphagia treatment in clinical practice.

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.

Artificial Intelligence-Assisted Throat Sensor Using Ionic Polymer-Metal Composite (IPMC) Material

Throat sensing has received increasing demands in recent years, especially for oropharyngeal treatment applications. The conventional videofluoroscopy (VFS) approach is limited by either exposing the patient to radiation or incurring expensive costs on sophisticated equipment as well as well-trained speech-language pathologists. Here, we propose a smart and non-invasive throat sensor that can be fabricated using an ionic polymer–metal composite (IPMC) material. Through the cation’s movement inside the IPMC material, the sensor can detect muscle movement at the throat using a self-generated signal. We have further improved the output responses of the sensor by coating it with a corrosive-resistant gold material. A support vector machine algorithm is used to train the sensor in recognizing the pattern of the throat movements, with a high accuracy of 95%. Our proposed throat sensor has revealed its potential to be used as a promising solution for smart healthcare devices, which can benefit many practical applications such as human–machine interactions, sports training, and rehabilitation.

A multinational consensus on dysphagia in Parkinson's disease: screening, diagnosis and prognostic value

Background

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by a combination of motor and non-motor dysfunction. Dysphagia is a common symptom in PD, though it is still too frequently underdiagnosed. Consensus is lacking on screening, diagnosis, and prognosis of dysphagia in PD.

Objective

To systematically review the literature and to define consensus statements on the screening and the diagnosis of dysphagia in PD, as well as on the impact of dysphagia on the prognosis and quality of life (QoL) of PD patients.

Methods

A multinational group of experts in the field of neurogenic dysphagia and/or PD conducted a systematic revision of the literature published since January 1990 to February 2021 and reported the results according to PRISMA guidelines. The output of the research was then analyzed and discussed in a consensus conference convened in Pavia, Italy, where the consensus statements were drafted. The final version of statements was subsequently achieved by e-mail consensus.

Results

Eighty-five papers were used to inform the Panel’s statements even though most of them were of Class IV quality. The statements tackled four main areas: (1) screening of dysphagia: timing and tools; (2) diagnosis of dysphagia: clinical and instrumental detection, severity assessment; (3) dysphagia and QoL: impact and assessment; (4) prognostic value of dysphagia; impact on the outcome and role of associated conditions.

Conclusions

The statements elaborated by the Consensus Panel provide a framework to guide the neurologist in the timely detection and accurate diagnosis of dysphagia in PD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10739-8.

Effects of age and gender on swallowing activity assessed by electromyography and laryngeal elevation

BACKGROUND

Quantitative assessment of swallowing function is necessary to prevent swallowing impairment due to ageing. Though surface electromyography (EMG) has been widely used to measure swallowing activity, the relationship between EMG results and swallowing function is unclear.

OBJECTIVE

This study examined the relationship between the temporal characteristics of muscle activity and laryngeal elevation (LE) during swallowing.

METHODS

This study analysed 60 healthy volunteers in two age groups (young, between 20 and 38 years; old, between 65 and 75 years), each containing the same number of male and female participants. Surface EMG signals were recorded from the suprahyoid and infrahyoid muscle groups (SH-EMG and IH-EMG, respectively). LE was measured using an array of pressure sensors. The participants swallowed 3 mL of water under three swallowing speed conditions: fast, normal and slow swallowing. The EMG duration, EMG time intervals before and after the onset of LE (pre-LE and post-LE intervals, respectively), and the LE velocity were analysed.

RESULTS

Both EMG duration and the post-LE interval of IH-EMG were significantly longer in the older group. As for the gender effect, the pre-LE interval of SH-EMG was significantly longer and the LE velocity was significantly higher in men than in women. Furthermore, there was a negative correlation between pre-LE interval and LE velocity in the fast swallowing condition.

CONCLUSION

Though ageing slightly prolonged the muscle activity time, gender influenced swallowing activity in a more complex manner. Therefore, it is important to take gender into account when examining swallowing function with increasing age.

The investigation of asymptomatic swallowing disorder through surface electromyography in the geriatric population

AIM

Swallowing is a vital activity. The difficulty while swallowing, referred to as swallowing disorder, is strongly associated with serious health problems in the elderly. The aim of this study is to enable early recognition of the swallowing function developing as an asymptomatic condition.

METHOD

Our study was conducted on elderly populations aged 65 years and over who met the exclusion criteria. Firstly, to be able to reach the number of sampling, "EAT-10 questionnaire", which also has a Turkish validation, was used to eliminate those with symptomatic swallowing disorders. The number of patients we reached was 320, but 7 dropped out of the study and therefore the study was carried out with a total of 313 [reached as 97.8% (up 95% G-power)].

RESULT

We used validated sEMG test in the quantitative (objective) detection of asymptomatic swallowing disorder. In this method, asymptomatic swallowing disorder was detected in 39 cases (12.4%).

CONCLUSION

Swallowing disorder without symptoms is frequent and the sEMG test is useful in detecting it in the elderly population.

Reproducibility and reaction time of swallowing as markers of dysphagia in parkinsonian syndromes

OBJECTIVE

To investigate reproducibility and reaction time of oropharyngeal swallowing in patients with Parkinson's disease (PD) and atypical parkinsonisms (APs).

METHODS

We enrolled 19 patients with PD, 30 with APs, and 20 healthy subjects. Presence and severity of dysphagia were assessed with clinical and fiberoptic endoscopic evaluations of swallowing. Reproducibility of the oral and pharyngeal phases of swallowing were respectively assessed by calculating the 'similarity index' of the electromyography activity of the submental/suprahyoid muscles and of the laryngeal-pharyngeal mechanogram during consecutive swallows. These were performed both 'on command' and spontaneously. The swallowing reaction time was also recorded.

RESULTS

Reproducibility of the oral phase of swallowing was reduced in patients with dysphagia, mainly when swallowing 'on command'. Swallowing reaction time was prolonged in dysphagic patients. These electrophysiological parameters did not vary among different parkinsonian syndromes and correlated with dysphagia severity.

CONCLUSIONS

Increased variability of oral swallowing automatisms and abnormal sensorimotor integration may be of relevance for the pathophysiology of dysphagia in parkinsonian syndromes.

SIGNIFICANCE

The electrophysiological assessment represents a valuable tool to investigate swallowing alterations in parkinsonian syndromes. It may also provide useful insights into clinical severity and pathophysiology of dysphagia, giving clues for the choice of the best therapeutic approach.

Anodal transcranial direct current stimulation and intermittent theta-burst stimulation improve deglutition and swallowing reproducibility in elderly patients with dysphagia

BACKGROUND

Dysphagia in the elderly, known as presbydysphagia, has become a relevant public health problem in several countries. Swallowing disorders may be a consequence of different neurological disorders (secondary presbydysphagia) or the expression of the aging process itself (primary presbydysphagia). We aimed to test the therapeutic potential of two different non-invasive brain stimulation (NIBS) techniques in subjects with primary or secondary presbydysphagia.

METHODS

A blinded randomized controlled trial with crossover design was carried out in 42 patients, randomly assigned to anodal transcranial direct current stimulation (tDCS) or intermittent theta-burst stimulation (TBS) group. Both tDCS and TBS were applied for 5 consecutive days over the right swallowing motor cortex. The swallowing function was assessed before and 1 and 3 months after the stimulation using the Dysphagia Outcome and Severity Scale (DOSS), scored based on clinical assessment and fiberoptic endoscopic evaluation of swallowing. An electrophysiological method was also applied to evaluate changes in the reproducibility of the swallowing behavior.

KEY RESULTS

Both real tDCS and TBS had beneficial effects on the swallowing function in patients with primary and secondary presbydysphagia. Anodal tDCS resulted in an improvement of 0.5 points in DOSS at 1-month follow-up (P = .014), whereas intermittent TBS induced an increase of 0.7 and 0.6 points at 1- and 3-month follow-up evaluations, respectively (P = .0001 and P = .005, respectively). Reproducibility of both the oral and pharyngeal phases of swallowing significantly increased at 1-month follow-up.

CONCLUSIONS AND INFERENCES

Our results suggest that non-invasive cortical stimulation may be useful for dysphagia recovery in elderly patients.

Correlation of Temporal Parameters of Laryngeal Excursion by Using Force-Sensing Resistor Sensors with Hyoid Motion in Videofluoroscopic Swallowing Study

Small flexible force-sensing resistor (FSR) sensors can detect laryngeal excursion during swallowing, but the detected laryngeal excursion has not been correlated with videofluoroscopic swallowing study (VFSS) results. Here, we tested the correlation of temporal parameters between the laryngeal excursion recording by FSR sensor and the hyoid motion recording by VFSS under simultaneously swallowing test recordings. Swallowing measurements were recorded in a radiological suite by simultaneously using VFSS and FSR sensors to detect hyoid motion and laryngeal excursion, respectively. Volunteers sat with their head vertical to the Frankfort plane. Two FSR sensors, each for detecting thyroid cartilage excursion and thumb pressing, were placed. VFSS images and FSR sensor signals during single 5-mL barium liquid (30% wt/volume %) bolus swallowing were collected and analyzed for four swallows per participant. In total, 15 men (28.0 ± 4.1 years old); 14 women (28.4 ± 4.2 years old) were recruited. Temporal parameters between VFSS and noninvasive system demonstrated a strong correlation by Pearson's correlation analysis: in men (R = 0.953-0.999) and in women (R = 0.813-0.982), except for VT1-V1 compared with FT1-F1, which demonstrated a moderate correlation in women (R = 0.648; all p < 0.001). Only VT1-V1 and FT1-F1 in women displayed a significant difference (p = 0.001). Therefore, this is the first study to simultaneous record VFSS and noninvasive signals by FSR sensor. The correlation of temporal parameters between these two tests was strong. This finding is valuable for future applications of this noninvasive swallowing study tool.

Swallowing Pressure Variability as a Function of Pharyngeal Region, Bolus Volume, Age, and Sex

OBJECTIVES

Within-individual movement variability occurs in most motor domains. However, it is unknown how pharyngeal swallowing pressure varies in healthy individuals. We hypothesized that: 1) variability would differ among pharyngeal regions; 2) variability would decrease with increased bolus volume; 3) variability would increase with age; and 4) there would be no sex differences.

STUDY DESIGN

Case series.

METHODS

We used pharyngeal high-resolution manometry to measure swallowing pressure in the following regions: velopharynx, tongue base, hypopharynx, and upper esophageal sphincter. Data were collected from 97 healthy adults (41 male) aged 21 to 89 years during thin liquid swallows: 2 mL, 10 mL, and participant-selected comfortable volume. Pressure variability was measured using coefficient of variation. Repeated measures analysis of variance was used to assess impacts of region, bolus volume, age, and sex on pressure variability.

RESULTS

There was a significant region × volume interaction (P < .001) and significant main effect of age (P = .005). Pressures in the hypopharynx region were more variable than all other regions (P ≤ .028), and pressures in the tongue base region were less variable than all other regions (P ≤ .002) except at 2 mL volumes (P = .065). Swallowing pressure variability was significantly different in the velopharynx and upper esophageal sphincter regions, with comfortable volume and 2 mL swallows having greater variability than 10 mL swallows (P ≤ .026). Pressure variability significantly increased with increasing age (P = .002). There were no effects of sex on pressure variability (P ≥ .15).

CONCLUSION

Pharyngeal swallowing pressure variability differs according pharyngeal region, volume, and age but not sex. Abnormal swallowing pressure variability may reflect deviations in motor control in persons with swallowing impairment, and results from this study can be used as normative data for future investigations evaluating swallowing pressure generation.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E52-E58, 2021.

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.

Does the M.D. Anderson Dysphagia Inventory correlate with dysphagia-limit and the Unified Parkinson Disease Rating Scale in early-stage Parkinson's disease?

BACKGROUND

Dysphagia is a common and critical condition that occurs in Parkinson's disease (PD), and it may appear in early stages. However, few reliable swallowing-related questionnaires are currently available. Therefore, finding efficient questionnaires for surveying dysphagia during the early stages of PD is necessary.

PURPOSE

This prospective study aimed to identify the correlations between the M.D. Anderson Dysphagia Inventory (MDADI) with dysphagia limit (DL) and the Unified Parkinson Disease Rating Scale (UPDRS) in early-stage PD.

METHODS

Forty-two patients with early-stage PD were recruited from a medical center. Data were collected for analysis of swallowing-related quality of life using the MDADI, symptom severity using the UPDRS, and DL using a noninvasive swallowing-respiration assessment system.

RESULTS

Our results showed that the MDADI, including its composite and subscales, was not correlated with DL. The composite scores of the MDADI were moderately correlated with the total score of the UPDRS (r = -0.504; p < 0.05) as well as with the second and third sections of the UPDRS scores (r = -0.453 to -0.478; p < 0.05). These results indicated that the impaired MDADI score can predict symptom severity (UPDRS), especially in activities of daily life and motor function.

CONCLUSION

The impaired MDADI for early-stage PD was determined, and decreased DL as a presentation of dysphagia could not be reflected by the MDADI. The MDADI may be used as a quick and convenient questionnaire for predicting the severity of early-stage PD, but not for the screening of early or subclinical dysphagia.

NEURAL CONTROL OF SWALLOWING

ABSTRACT BACKGROUND: Swallowing is a motor process with several discordances and a very difficult neurophysiological study. Maybe that is the reason for the scarcity of papers about it. OBJECTIVE: It is to describe the chewing neural control and oral bolus qualification. A review the cranial nerves involved with swallowing and their relationship with the brainstem, cerebellum, base nuclei and cortex was made. METHODS: From the reviewed literature including personal researches and new observations, a consistent and necessary revision of concepts was made, not rarely conflicting. RESULTS AND CONCLUSION: Five different possibilities of the swallowing oral phase are described: nutritional voluntary, primary cortical, semiautomatic, subsequent gulps, and spontaneous. In relation to the neural control of the swallowing pharyngeal phase, the stimulus that triggers the pharyngeal phase is not the pharyngeal contact produced by the bolus passage, but the pharyngeal pressure distension, with or without contents. In nutritional swallowing, food and pressure are transferred, but in the primary cortical oral phase, only pressure is transferred, and the pharyngeal response is similar. The pharyngeal phase incorporates, as its functional part, the oral phase dynamics already in course. The pharyngeal phase starts by action of the pharyngeal plexus, composed of the glossopharyngeal (IX), vagus (X) and accessory (XI) nerves, with involvement of the trigeminal (V), facial (VII), glossopharyngeal (IX) and the hypoglossal (XII) nerves. The cervical plexus (C1, C2) and the hypoglossal nerve on each side form the ansa cervicalis, from where a pathway of cervical origin goes to the geniohyoid muscle, which acts in the elevation of the hyoid-laryngeal complex. We also appraise the neural control of the swallowing esophageal phase. Besides other hypotheses, we consider that it is possible that the longitudinal and circular muscular layers of the esophagus display, respectively, long-pitch and short-pitch spiral fibers. This morphology, associated with the concept of energy preservation, allows us to admit that the contraction of the longitudinal layer, by having a long-pitch spiral arrangement, would be able to widen the esophagus, diminishing the resistance to the flow, probably also by opening of the gastroesophageal transition. In this way, the circular layer, with its short-pitch spiral fibers, would propel the food downwards by sequential contraction.

Methods for measuring swallowing pressure variability using high-resolution manometry

Any movement performed repeatedly will be executed with inter-trial variability. Oropharyngeal swallowing is a complex sensorimotor action, and swallow-to-swallow variability can have consequences that impact swallowing safety. Our aim was to determine an appropriate method to measure swallowing pressure waveform variability. An ideal variability metric must be sensitive to known deviations in waveform amplitude, duration, and overall shape, without being biased by waveforms that have both positive and sub-atmospheric pressure profiles. Through systematic analysis of model waveforms, we found a coefficient of variability (CV) parameter on waveforms adjusted such that the overall mean was 0 to be best suited for swallowing pressure variability analysis. We then investigated pharyngeal swallowing pressure variability using high-resolution manometry data from healthy individuals to assess impacts of waveform alignment, pharyngeal region, and number of swallows investigated. The alignment that resulted in the lowest overall swallowing pressure variability was when the superior-most sensor in the upper esophageal sphincter reached half its maximum pressure. Pressures in the tongue base region of the pharynx were least variable and pressures in the hypopharynx region were most variable. Sets of 3 - 10 consecutive swallows had no overall difference in variability, but sets of 2 swallows resulted in significantly less variability than the other dataset sizes. This study identified variability in swallowing pressure waveform shape throughout the pharynx in healthy adults; we discuss implications for swallowing motor control.

Metallic Nanoislands on Graphene for Monitoring Swallowing Activity in Head and Neck Cancer Patients

There is a need to monitor patients with cancer of the head and neck postradiation therapy, as diminished swallowing activity can result in disuse atrophy and fibrosis of the swallowing muscles. This paper describes a flexible strain sensor comprising palladium nanoislands on single-layer graphene. These piezoresistive sensors were tested on 14 disease-free head and neck cancer patients with various levels of swallowing function: from nondysphagic to severely dysphagic. The patch-like devices detected differences in (1) the consistencies of food boluses when swallowed and (2) dysphagic and nondysphagic swallows. When surface electromyography (sEMG) is obtained simultaneously with strain data, it is also possible to differentiate swallowing vs nonswallowing events. The plots of resistance vs time are correlated to specific events recorded by video X-ray fluoroscopy. Finally, we developed a machine-learning algorithm to automate the identification of bolus type being swallowed by a healthy subject (86.4%. accuracy). The algorithm was also able to discriminate between swallows of the same bolus from either the healthy subject or a dysphagic patient (94.7% accuracy). Taken together, these results may lead to noninvasive and home-based systems for monitoring of swallowing function and improved quality of life.

The biomechanical coordination during oropharyngeal swallowing: an evaluation with a non-invasive sensing system

Swallowing is a very important and complex physiological behaviour. The dynamic of swallowing has created great interest as any procedural abnormality will result in dysphagia and even lower quality of life. However, a non-invasive evaluation of biomechanical coordination during oropharyngeal swallowing, which includes the activities of the tongue, the hyoid and swallowing-related muscles, has not yet been achieved. In the present study, we recruited fifteen subjects, and a non-invasive sensing system composed of a pressure sensor, a bend sensor, surface electrodes and a microphone was created to simultaneously monitor tongue pressure, hyoid motion, and surface EMG of swallowing-related muscles, as well as take sound recordings, when the subjects swallowed 5 ml of water. In addition to obtaining the durations of certain motor events, the considerable time (beginning, peak and ending time) of tongue pressure production, suprahyoid and infrahyoid muscle activity and hyoid motion were successfully measured. Moreover, the significant correlations between swallowing-related muscles, tongue pressure, and the hyoid were confirmed. These findings suggest that the non-invasive sensing system has potential as a good candidate for monitoring and evaluating the oropharyngeal process of swallowing, which may be useful in clinical work involving dysphagia evaluation and rehabilitation.

Botulinum Toxin Is Effective in the Management of Neurogenic Dysphagia. Clinical-Electrophysiological Findings and Tips on Safety in Different Neurological Disorders

Background and Aims: Neurogenic dysphagia linked to failed relaxation of the upper esophageal sphincter (UES) can be treated by injecting botulinum toxin (BTX) into the cricopharyngeal (CP) muscle. We compared the effects of this treatment in different neurological disorders with dysphagia, to evaluate its efficacy over time including the response to a second injection. Materials and Methods: Sixty-seven patients with neurogenic dysphagia associated with incomplete or absent opening of the UES (24 with brainstem or hemispheric stroke, 21 with parkinsonian syndromes, 12 with multiple sclerosis, and 10 with spastic-dystonic syndromes secondary to post-traumatic encephalopathy) were treated with the injection of IncobotulinumtoxinA (dose 15-20 U) into the CP muscle under electromyographic guidance. The patients were assessed at baseline and after the first and second treatment through clinical evaluation and fiberoptic endoscopy of swallowing, while their dysphagia was quantified using the Dysphagia Outcome and Severity Scale (DOSS). An electrokinesiographic/electromyographic study of swallowing was performed at baseline. Results: Most patients responded to the first BTX treatment: 35 patients (52.2%) were classified as high responders (DOSS score increase >2 levels), while other 19 patients (28.4%) were low responders (DOSS score increase of ≤2 levels). The effect of the first treatment usually lasted longer than 4 months (67%), and in some cases up to a year. The treatment efficacy remained high also after the second injection: 31 patients (46.3%) qualified as high responders and other 22 patients (32.8%) showed a low response. Only in the parkinsonian syndromes group we observed a reduction in the percentage of high responders as compared with the first treatment. Side effects were mostly mild and reported in non-responders following the first injection. A severe side effect, consisting of ingestion pneumonia, was observed following the second BTX injection in two patients who had both been non-responders to the first. Non-responders were characterized electromyographically by higher values of the oropharyngeal interval. Conclusion: These findings confirm the effectiveness of IncobotulinumtoxinA injection in the treatment of neurogenic dysphagia due to hyperactivity and relaxation failure of the UES. Caution should be used as regards, the re-injection in non-responders to the first treatment.

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.

The interaction between breathing and swallowing in amyotrophic lateral sclerosis

The aim of the study is to determine the association between respiratory swallow patterns in amyotrophic lateral sclerosis (ALS) patients. Furthermore, it aims to clarify the role of the dysphagia limit in defining the relationship between swallowing disorders and respiratory disorders. Functional rating scales were used to describe swallowing and respiratory function. Swallowing was observed using the dysphagia limit. Dysphagia limit is the volume at which a second or more swallows are required to swallow the whole bolus. Laryngeal and chest movement sensors, pulmonary function tests, submental, and diaphragm electromyography activity were used to evaluate the relationship between swallowing and respiratory phase. Of the 27 patients included in the study, 14 were dysphagic and 13 were non-dysphagic. Tests showed normal respiratory function in 11 of the non-dysphagic patients and 3 of the dysphagic patients. There was a high correlation between the dysphagia limit and Amyotrophic Lateral Sclerosis Functional Rating Scale swallowing parameters. Non-dysphagic patients were able to swallow during inspiration but only six patients in the dysphagic group were able to swallow during inspiration. The occurrence of dysphagia in ALS is related to piecemeal deglutition and respiration consistency during swallowing. Detecting the timing of disturbances in the relationship between swallowing and respiration may be a way of identifying dysphagia. Dysphagia limit may be a useful, complementary test for assessing swallowing disturbances in amyotrophic lateral sclerosis.

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.

Modulation of Upper Esophageal Sphincter (UES) Relaxation and Opening During Volume Swallowing

UES opening occurs following cricopharyngeus deactivation and submental muscle contraction causing hyolaryngeal elevation and UES distraction. During impedance manometry, the inverse of impedance (admittance) can be used to measure bolus presence and infer UES opening. We hypothesized that the temporal relationship between UES relaxation, opening and hyolaryngeal elevation would change with increasing bolus volume. Simultaneous intramuscular cricopharyngeal (CP) electromyography (EMG), surface submental EMG (SM-EMG), and high-resolution impedance manometry were recorded in eight (aged 27 ± 7 years, 5 M) healthy volunteers, while swallowing 0.9 % saline boluses of 2, 5, 10, and 20 ml. Data were exported and analyzed via Matlab. Statistical analysis comprised repeated measures one-way ANOVA and Pearson correlation. A P value of <0.05 was considered significant. Duration of CP deactivation increased at 20 ml volume (P < 0.001). UES relaxation and opening increased with increasing bolus volume (P < 0.001); however, overall duration of SM activation did not change. As UES opening occurs progressively earlier with increasing volumes, peak SM-EMG activity occurs relatively later (P < 0.001) and shifts from occurring before to following peak UES distention. During healthy swallowing, there is sensory modulation of cricopharyngeal and submental muscle activity. Intrabolus pressures, transmitted from the tongue base and pharynx, play a progressively more important role in sphincter opening with increasing volume. The findings may explain why some healthy elderly and patients with oropharyngeal dysphagia have difficulty swallowing larger while tolerating smaller bolus volumes.

Non-invasive Assessment of Swallowing and Respiration Coordination for the OSA Patient

The objectives of this study are to investigate swallowing and its coordination with respiration in patients with obstructive sleep apnea (OSA). This is a prospective cohort study conducted in a tertiary referred Medical Center. A non-invasive method of assessing swallowing was used to detect the oropharyngeal swallowing parameters and the coordination with respiration during swallowing. The system used to assess swallowing detected: (1) movement of the larynx using a force-sensing resistor; (2) submental muscle activity using surface electromyography; and (3) coordination with respiration by measuring nasal airflow. Five sizes of water boluses (maximum 20 mL) were swallowed three times, and the data recorded and analyzed for each participant. Thirty-nine normal controls and 35 patients with OSA who fulfilled the inclusion criteria were recruited. The oropharyngeal swallowing parameters of the patients differed from the controls, including longer total excursion duration and shorter duration of submental muscles contraction. A longer swallowing respiratory pause (SRP), temporary coordination with respiration during swallowing, was demonstrated in the patients compared with the controls. The frequency of non-expiratory/expiratory pre- and postswallowing respiratory phase patterns of the patients was similar with the controls. There was significantly more piecemeal deglutition in OSA patients when clumping 10- and 20-mL water boluses swallowing together (p = 0.048). Oropharyngeal swallowing and coordination with respiration affected patients with OSA, and it could be detected using a non-invasive method. The results of this study may serve as a baseline for further research and help advance research methods in obstructive sleep apnea swallowing studies.

Peripheral component of laryngeal and pharyngeal motor evoked potentials

In this study, the responses of thyroarytenoid (TA) and cricopharyngeus (CP) muscles were simultaneously recorded to peripheral magnetic stimulation of the vagus nerve. Recordings were performed in 13 subjects by means of concentric needle EMG electrodes inserted in the TA and CP. Magnetic shocks were delivered to the vagus nerve with a round coil placed occipitally, while EMG was silent in the TA. In all subjects, clear-cut responses were obtained simultaneously in both muscles. In TA compared to CP, the maximum amplitude of the responses were higher, whereas the onset latency was shorter. Our results revealed that simultaneous recordings of TA and CP motor responses to occipital magnetic stimulation enabled a reliable evaluation of their peripheral innervation by the vagus nerve.

Dysphagia in Alzheimer's disease

OBJECTIVE

To investigate electrophysiological parameters of swallowing in all stages of Alzheimer's disease.

METHODS

Forty Alzheimer's disease patients, 20 age-matched normal controls and 20 young normal controls were included. Dysphagia limit (DL) and sequential water swallowing (SWS) tests were performed. Cardiac rhythm, respiration and sympathetic skin responses were concomitantly recorded.

RESULTS

Dysphagia was found in 30/40 (75%) of Alzheimer's disease patients. Mean volume at the DL test was significantly reduced (16.5±1.0mL) in the Alzheimer's disease group. Swallowing and apnea times in the SWS test were significantly prolonged in elderly controls, but even longer in Alzheimer's disease patients.

CONCLUSIONS

Alzheimer's disease patients had electrophysiological features of dysphagia, even in the early period of disease. The cortical involvement and severity of cognitive disorder can increase swallowing problems, but subclinical signs of dysphagia may be observed even in patients with mild or moderate Alzheimer's disease.

Predicting the activation states of the muscles governing upper esophageal sphincter relaxation and opening

The swallowing muscles that influence upper esophageal sphincter (UES) opening are centrally controlled and modulated by sensory information. Activation and deactivation of neural inputs to these muscles, including the intrinsic cricopharyngeus (CP) and extrinsic submental (SM) muscles, results in their mechanical activation or deactivation, which changes the diameter of the lumen, alters the intraluminal pressure, and ultimately reduces or promotes flow of content. By measuring the changes in diameter, using intraluminal impedance, and the concurrent changes in intraluminal pressure, it is possible to determine when the muscles are passively or actively relaxing or contracting. From these "mechanical states" of the muscle, the neural inputs driving the specific motor behaviors of the UES can be inferred. In this study we compared predictions of UES mechanical states directly with the activity measured by electromyography (EMG). In eight subjects, pharyngeal pressure and impedance were recorded in parallel with CP- and SM-EMG activity. UES pressure and impedance swallow profiles correlated with the CP-EMG and SM-EMG recordings, respectively. Eight UES muscle states were determined by using the gradient of pressure and impedance with respect to time. Guided by the level and gradient change of EMG activity, mechanical states successfully predicted the activity of the CP muscle and SM muscle independently. Mechanical state predictions revealed patterns consistent with the known neural inputs activating the different muscles during swallowing. Derivation of "activation state" maps may allow better physiological and pathophysiological interpretations of UES function.

Maximum upper esophageal sphincter (UES) admittance: a non-specific marker of UES dysfunction

BACKGROUND

Assessment of upper esophageal sphincter (UES) motility is challenging, as functionally, UES relaxation and opening are distinct. We studied novel parameters, UES admittance (inverse of nadir impedance), and 0.2-s integrated relaxation pressure (IRP), in patients with cricopharyngeal bar (CPB) and motor neuron disease (MND), as predictors of UES dysfunction.

METHODS

Sixty-six healthy subjects (n = 50 controls 20-80 years; n = 16 elderly >80 years), 11 patients with CPB (51-83 years) and 16 with MND (58-91 years) were studied using pharyngeal high-resolution impedance manometry. Subjects received 5 × 5 mL liquid (L) and viscous (V) boluses. Admittance and IRP were compared by age and between groups. A p < 0.05 was considered significant.

KEY RESULTS

In healthy subjects, admittance was reduced (L: p = 0.005 and V: p = 0.04) and the IRP higher with liquids (p = 0.02) in older age. Admittance was reduced in MND compared to both healthy groups (Young: p < 0.0001 for both, Elderly L: p < 0.0001 and V: p = 0.009) and CPB with liquid (p = 0.001). Only liquid showed a higher IRP in MND patients compared to controls (p = 0.03), but was similar to healthy elderly and CPB patients. Only admittance differentiated younger controls from CPB (L: p = 0.0002 and V: p < 0.0001), with no differences in either parameter between CPB and elderly subjects.

CONCLUSIONS & INFERENCES

The effects of aging and pathology were better discriminated by UES maximum admittance, demonstrating greater statistical confidence across bolus consistencies as compared to 0.2-s IRP. Maximum admittance may be a clinically useful determinate of UES dysfunction.

Integrated non-invasive measurements reveal swallowing and respiration coordination recovery after unilateral stroke

BACKGROUND

Oropharyngeal dysphagia is common after a stroke. Understanding the physiology of swallowing and its coordination with respiration in stroke recovery is crucially important.

METHODS

A non-invasive swallowing assessment method was used to detect oropharyngeal swallowing and respiration coordination simultaneously during the swallowing process. This system detected movement of the larynx, submental muscle activity, and nasal airflow. Six different sizes of water boluses (maximum of 20 mL) were swallowed and assessed for each subject.

KEY RESULTS

We recruited 59 healthy participants and 38 first ever unilateral stroke patients completed baseline and follow-up assessments at 3, 6, and 9 months poststroke. The results showed that oropharyngeal swallowing parameters in unilateral stroke deviate from normal patterns. For respiration coordination, the unilateral stroke group had longer swallowing apnea duration but similar frequencies of pre- and postswallowing respiratory phase patterns compared with the healthy controls. The probability of piece-meal deglutition was higher in the stroke group than in the control group. Additionally, there were gradually decreasing piece-meal deglutition probabilities among the stroke patients at follow-up, and none differed statistically from those of the controls at 6 months poststroke.

CONCLUSIONS & INFERENCES

The non-invasive swallowing and respiration assessment method applied in this study detected the changes manifested in swallowing and respiration during the subacute phase of recovery in 6 months after a unilateral stroke. The study results serve as a baseline for further research and help advance dysphagia research methodologies. These assessments may be combined with bedside evaluations for clinical application.

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.

Electrophysiological Techniques to Evaluate Swallowing in Central and Peripheral Nervous System Disorders

Neurogenic dysphagia is a frequent condition that may result in serious complications. Despite high incidence of neurogenic dysphagia, the neurologist is not really interested in its clinical diagnosis and management. In this review, several neurophysiological methods are described to evaluate the neurogenic dysphagia. These kinds of assessment methods are important for early diagnosis and some management strategies against to progressive swallowing pathology. The longitudinal follow-up of the patients also provides data about the prognosis of dysphagia. In our opinion, the neurophysiological methods presented in this review are reliable, cheap, and easy applicable quantitative tests to detect and follow both clinical and subclinical dysphagia. All these electrophysiological techniques can be applied within the discipline of the EMG laboratory.

Development of a portable non-invasive swallowing and respiration assessment device

Dysphagia is a condition that happens when a person cannot smoothly swallow food from the mouth to the stomach. It causes malnourishment in patients, or can even cause death due to aspiration pneumonia. Recently, more and more researchers have focused their attention on the importance of swallowing and respiration coordination, and the use of non-invasive assessment systems has become a hot research trend. In this study, we aimed to integrate the timing and pattern monitoring of respiration and swallowing by using a portable and non-invasive approach which can be applied at the bedside in hospitals or institutions, or in a home environment. In this approach, we use a force sensing resistor (FSR) to detect the motions of the thyroid cartilage in the pharyngeal phase. We also use the surface electromyography (sEMG) to detect the contraction of the submental muscle in the oral phase, and a nasal cannula to detect nasal airflow for respiration monitoring during the swallowing process. All signals are received and processed for swallowing event recognition. A total of 19 volunteers participated in the testing and over 57 measurements were made. The results show that the proposed approach can effectively distinguish the swallowing function in people of different ages and genders.

Upper esophageal sphincter mechanical states analysis: a novel methodology to describe UES relaxation and opening

The swallowing muscles that influence upper esophageal sphincter (UES) opening are centrally controlled and modulated by sensory information. Activation of neural inputs to these muscles, the intrinsic cricopharyngeus muscle and extrinsic suprahyoid muscles, results in their contraction or relaxation, which changes the diameter of the lumen, alters the intraluminal pressure and ultimately inhibits or promotes flow of content. This relationship that exists between the changes in diameter and concurrent changes in intraluminal pressure has been used previously to calculate the “mechanical states” of the muscle; that is when the muscles are passively or actively, relaxing or contracting. Diseases that alter the neural pathways to these muscles can result in weakening the muscle contractility and/or decreasing the muscle compliance, all of which can cause dysphagia. Detecting these changes in the mechanical state of the muscle is difficult and as the current interpretation of UES motility is based largely upon pressure measurement (manometry), subtle changes in the muscle function during swallow can be missed. We hypothesized that quantification of mechanical states of the UES and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern the timing and extent of UES opening during swallowing. To achieve this we initially analyzed swallows captured by simultaneous videofluoroscopy and UES pressure with impedance recording. From these data we demonstrated that intraluminal impedance measurements could be used to determine changes in the internal diameter of the lumen when compared to videofluoroscopy. Then using a database of pressure-impedance studies, recorded from young and aged healthy controls and patients with motor neuron disease, we calculated the UES mechanical states in relation to a standardized swallowed bolus volume, normal aging and dysphagia pathology. Our results indicated that eight different mechanical states were almost always seen during healthy swallowing and some of these calculated changes in muscle function were consistent with the known neurally dependent phasic discharge patterns of cricopharyngeus muscle activity during swallowing. Clearly defined changes in the mechanical states were observed in motor neuron disease when compared to age matched healthy controls. Our data indicate that mechanical state predictions were simple to apply and revealed patterns consistent with the known neural inputs activating the different muscles during swallowing.

Electrophysiological evaluation of oropharyngeal Dysphagia in Parkinson's disease

Parkinson’s disease (PD) is a chronic, neurodegenerative movement disorder that typically affects elderly patients. Swallowing disorders are highly prevalent in PD and can have grave consequences, including pneumonia, malnutrition, dehydration and mortality. Neurogenic dysphagia in PD can manifest with both overt clinical symptoms or silent dysphagia. Regardless, early diagnosis and objective follow-up of dysphagia in PD is crucial for timely and appropriate care for these patients. In this review, we provide a comprehensive summary of the electrophysiological methods that can be used to objectively evaluate dysphagia in PD. We discuss the electrophysiological abnormalities that can be observed in PD, their clinical correlates and the pathophysiology underlying these findings.

Quantifying contributions of the cricopharyngeus to upper esophageal sphincter pressure changes by means of intramuscular electromyography and high-resolution manometry

OBJECTIVES

We sought to determine whether the association between cricopharyngeus muscle activity and upper esophageal sphincter pressure may change in a task-dependent fashion. We hypothesized that more automated tasks related to swallow or airway protection would yield a stronger association than would more volitional tasks related to tidal breathing or voice production.

METHODS

Six healthy adult subjects underwent simultaneous intramuscular electromyography of the cricopharyngeus muscle and high-resolution manometry of the upper esophageal sphincter. Correlation coefficients were calculated to characterize the association between the time-linked series.

RESULTS

Cricopharyngeus muscle activity was most strongly associated with upper esophageal sphincter pressure during swallow and effortful exhalation tasks (r = 0.77 and 0.79, respectively; P < .01). The association was also less variable during swallow and effortful exhalation.

CONCLUSIONS

These findings suggest a greater coupling for the more automatic tasks, and may suggest less coupling and more flexibility for the more volitional, voice-related tasks. These findings support the important role of central patterning for respiratory- and swallow-related tasks.

Aging-related changes in swallowing, and in the coordination of swallowing and respiration determined by novel non-invasive measurement techniques

AIM

Previous studies have shown that the process of swallowing changes with aging, a phenomenon known as presbyphagia. These subtle and subclinical age-related changes make older adults more vulnerable to dysphagia during disease insults. However, there are limited studies of the swallowing process in older adults, because measurements are typically invasive or require exposure to X-rays. In the present study, we used integrated non-invasive measurements to determine aging-related changes of swallowing, and in the coordination of swallowing and respiration for a population of healthy participants.

METHODS

The non-invasive system provided measurements of larynx movement with piezoelectric sensors, submental muscle activity with surface electromyography and respiration-swallowing coordination by measurement of nasal airflow. We recruited 112 healthy participants from the community, 35 in a young-age group (age 20-30 years), 38 in a middle-age group (age 31-50 years) and 39 in an old-age group (age 51-70 years).

RESULTS

The oropharyngeal swallowing parameters of the old-age group had delayed onset latency and longer swallowing apnea duration relative to the other groups, and these differences were greater for larger boluses. The middle- and old-age groups had less expiratory-expiratory respiratory phase pattern than the young-age group. The probability of piecemeal deglutition was highest in the old-age group and lowest in the young-age group. These results show that the phases of oropharyngeal swallowing and the coordination of swallowing with respiration gradually change with aging.

CONCLUSIONS

We used integrated non-invasive measurements to document age-related changes in swallowing, and in the coordination of swallowing and respiration in healthy adults.

Transcranial direct current stimulation enhances sucking of a liquid bolus in healthy humans

BACKGROUND

Transcranial direct current stimulation (tDCS) is a non-invasive technique used for modulating cortical excitability in vivo in humans. Here we evaluated the effect of tDCS on behavioral and electrophysiological aspects of physiological sucking and swallowing.

METHODS

Twelve healthy subjects underwent three tDCS sessions (anodal, cathodal and sham stimulation) on separate days in a double-blind randomized order. The active electrode was placed over the right swallowing motor cortex. Repeated sucking and swallowing acts were performed at baseline and at 15 and 60 min after each tDCS session and the mean liquid bolus volume ingested at each time point was measured. We also calculated average values of the following electrophysiological parameters: 1) area and 2) duration of the rectified EMG signal from the suprahyoid/submental muscles related to the sucking and swallowing phases; 3) EMG peak amplitude for the sucking and swallowing phases; 4) area and peak amplitude of the laryngeal-pharyngeal mechanogram; 5) oropharyngeal delay.

RESULTS

The volume of the ingested bolus significantly increased (by an average of about 30% compared with the baseline value) both at 15 and at 60 min after the end of anodal tDCS. The electrophysiological evaluation after anodal tDCS showed a significant increase in area and duration of the sucking phase-related EMG signal.

CONCLUSIONS

Anodal tDCS leads to stronger sucking of a liquid bolus in healthy subjects, likely by increasing recruitment of cortical areas of the swallowing network. This finding might open up interesting perspectives for the treatment of patients suffering from dysphagia due to various pathological conditions.

Evaluating the tongue-hold maneuver using high-resolution manometry and electromyography

The tongue-hold maneuver is a widely used clinical technique designed to increase posterior pharyngeal wall movement in individuals with dysphagia. It is hypothesized that the tongue-hold maneuver results in increased contraction of the superior pharyngeal constrictor. However, an electromyographic study of the pharynx and tongue during the tongue-hold is still needed to understand whether and how swallow muscle activity and pressure may change with this maneuver. We tested eight healthy young participants using simultaneous intramuscular electromyography with high-resolution manometry during three task conditions including (a) saliva swallow without maneuver, (b) saliva swallow with the tongue tip at the lip, and (c) saliva swallow during the tongue-hold maneuver. We tested the hypothesis that tongue and pharyngeal muscle activity would increase during the experimental tasks, but that pharyngeal pressure would remain relatively unchanged. We found that the pre-swallow magnitude of tongue, pharyngeal constrictor, and cricopharyngeus muscle activity increased. During the swallow, the magnitude and duration of tongue and pharyngeal constrictor muscle activity each increased. However, manometric pressures and durations remained unchanged. These results suggest that increased superior pharyngeal constrictor activity may serve to maintain relatively stable pharyngeal pressures in the absence of posterior tongue movement. Thus, the tongue-hold maneuver may be a relatively simple but robust example of how the medullary swallow center is equipped to dynamically coordinate actions between tongue and pharynx. Our findings emphasize the need for combined modality swallow assessment to include high-resolution manometry and intramuscular electromyography to evaluate the potential benefit of the tongue-hold maneuver for clinical populations.

Rethinking Rehab: Skill-Based Training for Swallowing Impairment

Current rehabilitation approaches for swallowing impairment are limited by a general lack of specificity to associated pathophysiology, with many of our practices focusing on increasing strength of muscle activation. However, alternative rehabilitative options are emerging. One of these speculates on the concept of “skill training” for swallowing rehabilitation in neurogenic dysphagia. The presumed intent of this approach is to modulate neural substrates and refine motor planning for swallowing using intrinsically generated cortical modulation and adaptive practice. This manuscript provides a discussion of skill training in the context of physical rehabilitation, illustrating how this information may translate to the diagnosis and remediation of swallowing impairment. This information prompts the consideration of more diverse swallowing pathophysiologies, beyond peripheral muscle weakness. The focus on skill training approaches provides a pathway by which greater specificity of diagnosis and treatment can occur.

Dynamic change in hyoid muscle length associated with trajectory of hyoid bone during swallowing: analysis using 320-row area detector computed tomography

Research on muscle activation patterns during swallowing has been limited. Newly developed 320-row area detector computed tomography (320-ADCT) has excellent spatial and temporal resolution, which facilitates identification of laryngopharyngeal structures and quantitative kinematic analysis of pharyngeal swallowing. We investigated muscle activity patterns by observing the changes in length of hyoid muscles. 320-ADCT was performed in 26 healthy males while swallowing. The following parameters were analyzed three-dimensionally: 1) origins and insertions of the stylohyoid, anterior and posterior digastric, mylohyoid, geniohyoid, and thyrohyoid muscles; and 2) movement of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles began to shorten simultaneously during the initial stage of swallowing. The shortening of these muscles occurred during the upward movement of the hyoid bone. Subsequently, the geniohyoid, thyrohyoid, and anterior digastric muscles began to shorten, synchronizing with the forward movement of the hyoid bone. A significant correlation was observed between the shortened muscle lengths of the stylohyoid, posterior digastric, and mylohyoid muscles and the upward movement of the hyoid bone ( r = 0.45–0.65). A correlation was also observed between the shortened muscle length of the geniohyoid muscle and the forward movement of the hyoid bone ( r = 0.61). In this study, the sequence of muscle activity during pharyngeal swallowing remained constant. Serial shortening of the hyoid muscles influenced the trajectory of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles initiated the swallowing reflex and contributed to upward movement of the hyoid bone. The geniohyoid is a key muscle in the forward movement of the hyoid bone.

Development of a system to monitor laryngeal movement during swallowing using a bend sensor

Background

Swallowing dysfunction (also known as dysphagia), which results in a deterioration of nutritional intake, slows rehabilitation and causes aspiration pneumonia, is very common following neurological impairments. Although videofluorographic (VF) examination is widely used for detecting aspiration, an objective and non-invasive method for assessing swallowing function has yet to be established because of a lack of adequate devices and protocols. In this paper, a bend sensor whose resistance is altered by bending was introduced to monitor swallowing-related laryngeal movement.

Methods

Six healthy male volunteers were recruited in the present study. Specific time points on the signal waveform produced by the bend sensor were defined to describe laryngeal movement by differential analysis. Additionally, the physiological significance of the obtained waveform was confirmed by analyzing the sequential correlations between the signal waveform from the bend sensor and hyoid bone kinetics simultaneously recorded by VF.

Results

Seven time points were successfully defined on the signal waveform to reference laryngeal movement. Each time point was well correlated with certain VF events, with evidence of no significant time lags, and there were positive correlations between waveform time points and matched VF events. Furthermore, obvious similarities were noticed between the duration of each phase on the signal waveform and the duration of the matched hyoid bone activity.

Conclusions

The present monitoring system using a bend sensor might be useful for observing the temporal aspects of laryngeal movement during swallowing, and it was well coordinated with hyoid bone movement.

Electrophysiological patterns of oropharyngeal swallowing in multiple sclerosis

OBJECTIVE

We performed an electrophysiological study of swallowing (EPSS) in multiple sclerosis (MS) to describe oropharyngeal swallowing abnormalities and to analyze their correlations with dysphagia and with overall neurological impairment.

METHODS

Neurological examinations were quantified using the Kurtzke Functional Systems and the Expanded Disability Status Scale (EDSS). Dysphagia was evaluated using the Dysphagia in Multiple Sclerosis (DYMUS) questionnaire, while fiberoptic endoscopic evaluation of swallowing (FEES) was used to establish the degree of aspiration and penetration, graded using the penetration-aspiration scale (PAS). The EPSS measured the duration of suprahyoid/submental muscle EMG activity (SHEMG-D), the duration of the laryngeal-pharyngeal mechanogram (LPM-D), and the duration of the pause in cricopharyngeal muscle EMG activity (CPEMG-PD); it also measured the interval between onset of the suprahyoid/submental muscle EMG activity (SHEMG) and onset of the laryngeal-pharyngeal mechanogram (I-SHEMG-LPM).

RESULTS

92% of patients showed at least one electrophysiological abnormality. I-SHEMG-LPM correlated positively with the DYMUS questionnaire. I-SHEMG-LPM, SHEMG-D, and DYMUS correlated positively with the PAS. Moderate to severe bladder sphincter dysfunction was associated with a significant reduction, or absence, of CPEMG-PD.

CONCLUSION

EPSS improves our understanding of the pathophysiology of dysphagia in MS.

SIGNIFICANCE

This investigation could be useful in MS patients with swallowing abnormalities.

The interaction between breathing and swallowing in healthy individuals

In this article, we aimed at investigating the interaction between breathing and swallowing patterns in normal subjects. Ten healthy volunteers were included in the study. Diaphragm EMG activity was recorded by a needle electrode inserted into the 7th or 8th intercostal space. Swallowing was monitored by submental EMG activity, and laryngeal vertical movement was recorded by using a movement sensor. A single voluntary swallow was initiated during either the inspiration or expiration phases of respiration, and changes in EMG activity were evaluated. When a swallow coincided with either inspiration or expiration, the duration of the respiratory phase was prolonged. Normal subjects were able to voluntarily swallow during inspiration. During the inspiration phase with swallowing, diaphragmatic activity did not ceased and during the expiration phase with swallowing, there was a muscle activity in the diaphragm muscle.