Voluntary Swallowing Research Articles

Effect of carbonation and thickening on voluntary swallow in healthy humans.

Liquid modification is a widely established strategy of treatment for patients with dysphagia. The modification of liquid particularly by thickening or carbonation is a common approach to promote safe swallowing. This study sought to investigate how carbonated and/or thickened water modulates swallowing behaviours during swallowing in healthy young individuals. Thirty-one healthy volunteers (9 men, 22 women; mean age ± standard deviation [SD], 25.7 ± 6.2 years) were instructed to swallow 20 mL of water, carbonated water and carbonated juice with and without added thickening agent. Electromyograms (EMGs) of the suprahyoid (S-hyo) muscles were recorded to evaluate swallowing behaviours. Obtained S-hyo EMG bursts was analysed using the following outcome parameters: onset latency, the time between swallowing que to onset of EMG burst; rising time and falling time, defined as the time between onset and peak, and between peak and offset, respectively; duration, defined as the time between onset and offset of EMG burst; and area integral value under the waveform. Effects of thickening demonstrated the extended onset latency, EMG burst duration including falling time and the larger area of EMG in thickened liquid compared to thin liquid, but there was not much difference between thin and thickened carbonated liquids. Carbonation significantly decreased the duration including falling time for thickened but not for thin liquids. Patients with dysphagia can benefit from use of carbonated or thickened water while the effects on swallowing physiology may differ between carbonation and thickening.

Stomach Foreign Body: A Retrospective Study with a Review

Foreign bodies in the stomach may be accidental or voluntary swallowing. Most foreign bodies are due to unintentional ingestion except in insane people or drug peddlers who may be voluntary. Most of the time, coins are accidentally ingested by children. A rare phenomenon is accidental ingestion of a size 16 to 20 cm in length (toothbrush) foreign body in a sane person. Oesophageal foreign bodies are not as risky as airway foreign bodies. These foreign bodies can obstruct and are located at the oesophagus cricopharynx constriction, the crossover of the aortic arch at the mid-oesophagus, and the lower end. After reaching the stomach, most ingested foreign bodies less than 6 cm will pass uneventfully through the gastrointestinal tract, as in 10 patients who consumed one/two rupee coins. Nevertheless, long and rigid foreign bodies like toothbrushes can result in gastrointestinal impaction, perforation and bleeding. Moreover, there have been a few case reports of spontaneous passage of a toothbrush, and promptly removing such ingested foreign objects is recommended before complications develop. Treatment option remains controversial considering the waiting policy or intervention, either endoscopic or surgical. This study describes 11 patients, 10 cases of coin ingestion and one case of the swallowed toothbrush. Ten cases of coin ingestion were managed conservatively. Upper midline laparotomy was done to remove the toothbrush as removal via flexible endoscopy failed. A swallowed toothbrush is a special clinical challenge. Early retrieval of the toothbrush is critical for reducing morbidity.

Effects of interferential current electrical stimulation (IFCS) on mastication and swallowing function in healthy young adults: A preliminary study.

This study aimed to investigate the effects of interferential current electrical stimulation (IFCS) on masticatory and swallowing function. Twenty healthy young adults were enrolled. The measurement items were spontaneous swallowing frequency (SSF), voluntary swallowing frequency (VSF), saliva secretion volume (SSV), glucose elution volume (GEV), and velocity of chew (VOC). All participants underwent both IFCS and sham stimulation (without stimulation, sham). Two sets of independent IFCS electrodes were placed on the bilateral neck. The precise location of the upper electrodes was just below the angle of the mandible, while the lower electrodes were placed at the anterior border of the sternocleidomastoid muscle. The intensity of IFCS was determined to be one level below the perceptual threshold that all participants felt discomfort. Statistical analysis was performed using a two-way repeated measures analysis of variance. For IFCS, the results of each measurement before and during stimulation were SSF: 1.16 and 1.46, VSF: 8.05 and 8.45, SSV: 5.33 and 5.56 g, GEV: 171.75 and 208.60 mg/dL, and VOC: 87.20 and 95.20, respectively. SSF, GEV, and VOC during stimulation were significantly increased by IFCS (SSF, p = .009; GEV, p = .048; and VOC, p = .007). Following sham stimulation, the results were SSF: 1.24 and 1.34, VSF: 7.75 and 7.90, SSV: 5.65 and 6.04 g, GEV: 176.45 and 187.35 mg/dL, and VOC: 91.35 and 88.25, respectively. While no significant differences were observed in the sham group, our findings suggest that IFCS of the superior laryngeal nerve may impact not only the swallowing function but also the masticatory function.

Brain Activation Site of Laryngeal Elevation During Swallowing: An fMRI Study.

The object of this study is to investigate dysphagia caused by reduced laryngeal elevation in patients poststroke. The central mechanism of laryngeal elevation during swallowing was explored by comparing the brain activation area before and after treatment with that of healthy subjects. The treatment group included patients diagnosed with dysphagia poststroke that showed reduced laryngeal elevation. They were treated with electrical stimulation at the motor points of the muscles related to laryngeal elevation. Functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) was used to observe brain activation of the normal healthy control group and treatment group during voluntary swallowing. Independent sample t test and paired sample t test were used to analyze the differences in brain activation between and within the groups. Compared with the control group, no activation was observed in the brainstem and putamen regions of the experimental group before treatment. Statistics showed that the experimental group had a wider range of brain activation than the control group pretreatment, including the left supplementary motor area, the cingulate gyrus, the inferior frontal gyrus, the right thalamus, and the right putamen. After the electrical stimulation, the brain stem subregion, the left cerebellar lobule IV and V, and parts of the cerebral cortex were more active, while the left supplementary motor area, paracentral lobule, and occipital lobule were less active post-treatment. (1) The brainstem and putamen are the specific brain regions that control laryngeal movement. (2) The enhanced activation of the cortical-basal ganglia-thalamic circuit after stroke is a compensatory mechanism. (3) The improvement of hyoid bone elevation was related to the enhanced activation of the IV and V lobes of the cerebellar hemisphere. The over-activation of the supplementary motor area poststroke would subside once the motor function improved.

Neurological examination in healthy adult inland bearded dragons (Pogona vitticeps)

To evaluate neurological tests and expected results in inland bearded dragons (Pogona vitticeps) and generate recommendations for bearded dragon-specific neurological examination. 26 healthy adult inland bearded dragons. A complete neurological examination utilizing tests described in both mammals and reptiles was performed on each lizard, and test feasibility and outcome were recorded. Tests with poor feasibility included oculocardiac reflex (successfully completed in 62% [16/26] of animals) and voluntary ambulation and swallowing by use of a food item (0% [0/26] of animals). Tests with outcomes considered abnormal in mammals but attributable to normal bearded dragon behavior included head position (head tilt present in 12% [3/26]) and head movement (head bob present in 4% [1/26]). Many tests had absent or inconsistent outcomes, including menace response (present in 19% [5/26]), proprioceptive positioning (present in 4% [1/26] in the thoracic limbs and 0% [0/26] in the pelvic limbs), vent reflex (present in 27% [7/26]), and myotatic reflexes (biceps present in 8% [2/26]; patellar, gastrocnemius, and triceps present in 0% [0/26]). Extensor postural thrust was absent in all successfully tested animals, but a novel reflex termed the caudal thoracic extensor reflex was noted instead in all observed animals (100% [21/21]). Tests with poor feasibility or inconsistent outcomes should have low priority or be excluded from neurological examinations of inland bearded dragons. Normal behaviors should be considered for head position and movement. A bearded dragon-specific neurological examination protocol derived from these findings is described and recommended in order to decrease stress and improve neurolocalization.

Relationship between demographic and cephalometric measures and electromyographic activityu of the facial musculature. A preliminary study in children and adolescents

Surface electromyography (EMGS) is used to evaluate the electromyographic activity of the orofacial musculature at rest, or when performing certain activities such as swallowing saliva or water, or tasks of maximum voluntary contraction. Numerous studies have evaluated the relationship between facial morphology and muscle activity, with contradictory results. The aim of this study was to determine whether there are significant differences in the electromyographic activity of the orofacial musculature as a function of the variables: age, height, weight, facial pattern and skeletal class. For this purpose, 81 patients with dental malocclusion were selected (35 males and 46 females, aged 6 to 17 years). Bilateral EMGS activity of the temporalis, masseter, orbicularis oris of the upper and lower lip of the mouth and suprahyoid muscles was measured in the resting position, maximum voluntary contraction and swallowing of saliva 2 ml of water. The results obtained show that the mandibular plane and the ANB angle present significant differences in all the variables of EMGS activity; however, the facial pattern only shows significant differences in the mean deviation of muscle activity. Skeletal class shows no significant effect on any of the EMGS variables recorded. The variables Age, Weight and Height show significant results on all EMGS activity variables. The variable Sex only shows significant results in the mean deviation of muscle activity. This work supports previous studies that found no significant results based on facial pattern and skeletal class. It would be advisable to perform a more exhaustive analysis of the muscles involved and their relationship between the different tasks evaluated, and to increase the sample size of patients with skeletal Class III in order to reach more definitive conclusions.

Singing Experience Influences RSST Scores.

It has recently been shown that the aging population is refractory to the maintenance of swallowing function, which can seriously affect quality of life. Singing and vocal training contribute to mastication, swallowing and respiratory function. Previous studies have shown that singers have better vocal cord health. No consensus has been reached as to how vocal training affects swallowing ability. Our study was designed to establish evidence that singers are statistically superior at inducing the swallowing reflex. To test our hypothesis, we undertook a clinical trial on 55 singers and 141 non-singers (mean age: 60.1 ± 11.7 years). This cross-sectional study with propensity score matching resulted in significant differences in a repetitive saliva swallowing test among singers: 7.1 ± 2.4, n = 53 vs. non-singers: 5.9 ± 1.9, n = 53, p < 0.05. We conclude that singing can serve an important role in stabilizing the impact of voluntary swallowing on speech.

Swallowing and aspiration during sleep in patients with obstructive sleep apnea versus control individuals.

Study ObjectivesThere are only a few reports on voluntary swallowing during sleep; therefore, this study aimed to propose a method for observing voluntary swallowing during sleep using polysomnography. The frequency of voluntary swallowing during sleep and the factors related to swallowing and aspiration during sleep were investigated.MethodsPolysomnography records of 20 control subjects and 60 patients with obstructive sleep apnea (OSA) (mild, moderate, and severe groups; n = 20 each) were collected. Simultaneous increases in the electromyographic potentials of the submental and masseter muscles, termed coactivation, and declining oronasal airflow (SA) were extracted as “swallowing.” The cough reflex that occurred during sleep was extracted as “aspiration.” The frequency of swallowing events was compared among the different OSA severity groups. Subsequently, a multivariate regression analysis was performed.ResultsThe average frequency of coactivation with SA in control subjects was 4.1 events/h and that without SA was 1.7 events/h. These frequencies increased with the severity of OSA during non-REM sleep. The distance of the hyoid to the Frankfurt plane was associated with the frequency of coactivation with (β = 0.298, p = 0.017) as well as without SA (β = 0.271, p = 0.038). The frequency of coactivation without SA was associated with aspiration (B = 0.192, p = 0.042).ConclusionsOur data provide new insights into the relationship between swallowing and aspiration during sleep. We found that the longer the distance from the hyoid bone to the Frankfurt plane, the higher the coactivation without SA, which could lead to aspiration during sleep.Clinical TrialsRetrospective observational study of swallowing during sleep in obstructive sleep apnea patients using polysomnography, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000050460, UMIN000044187.

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

Electrical stimulation therapy is effective for patients with dysphagia. However, because of the pain, strong stimulation cannot be applied. Although magnetic stimulation induces less pain, there are no reports on magnetic stimulation being synchronised with a swallowing reflex. This study aimed to determine whether it is possible to induce magnetic stimulation during a voluntary swallowing using electromyography (EMG)-triggered peripheral magnetic stimulation and to evaluate its effect on healthy individuals. A total of 20 healthy adults in seated position were instructed to swallow saliva and 10ml of barium under videofluoroscopy. For concomitant use of magnetic stimulation, a magnetic stimulus for suprahyoid muscles at 30Hz frequency was applied for 2s when the EMG level in the sternohyoid muscle exceeded the threshold. During the voluntary swallowing, the movement of the hyoid bone and opening width of the upper oesophageal sphincter (UES) were measured. Furthermore, pressure topography was evaluated in 6 subjects using high-resolution manometry. The magnetic stimulation significantly extended the movement time of the hyoid bone (p<0.001). During liquid deglutition, significant increases were observed in the anterior maximum movement distance of the hyoid bone (p<0.05), opening width of the UES (p<0.001) and anterior movement distance of the hyoid bone at the maximum UES opening (p<0.01). In the pressure topography, the maximum pressure immediately after UES closure significantly decreased with magnetic stimulation (p<0.05). EMG-triggered peripheral magnetic stimulation made it possible to apply magnetic stimulation during a voluntary swallowing.

Coordination of Respiration, Swallowing, and Chewing in Healthy Young Adults.

Examining the coordination of respiration and swallowing is important for elucidating the mechanisms underlying these functions and assessing how respiration is linked to swallowing impairment in dysphagic patients. In this study, we assessed the coordination of respiration and swallowing to clarify how voluntary swallowing is coordinated with respiration and how mastication modulates the coordination of respiration and swallowing in healthy humans. Twenty-one healthy volunteers participated in three experiments. The participants were asked to swallow 3 ml of water with or without a cue, to drink 100 ml of water using a cup without breathing between swallows, and to eat a 4-g portion of corned beef. The major coordination pattern of respiration and swallowing was expiration–swallow–expiration (EE type) while swallowing 3 ml of water either with or without a cue, swallowing 100 ml of water, and chewing. Although cueing did not affect swallowing movements, the expiratory time was lengthened with the cue. During 100-ml water swallowing, the respiratory cycle time and expiratory time immediately before swallowing were significantly shorter compared with during and after swallowing, whereas the inspiratory time did not differ throughout the recording period. During chewing, the respiratory cycle time was decreased in a time-dependent manner, probably because of metabolic demand. The coordination of the two functions is maintained not only in voluntary swallowing but also in involuntary swallowing during chewing. Understanding the mechanisms underlying respiration and swallowing is important for evaluating how coordination affects physiological swallowing in dysphagic patients.

Swallowing-related neural oscillation: an intracranial EEG study.

ObjectiveSwallowing is a unique movement due to the indispensable orchestration of voluntary and involuntary movements. The transition from voluntary to involuntary swallowing is executed within milliseconds. We hypothesized that the underlying neural mechanism of swallowing would be revealed by high‐frequency cortical activities.MethodsEight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus and cortical oscillatory changes, including the high γ band (75–150 Hz) and β band (13–30 Hz), were investigated at the time of mouth opening, water injection, and swallowing.ResultsIncreases in high γ power associated with mouth opening were observed in the ventrolateral prefrontal cortex (VLPFC) with water injection in the lateral central sulcus and with swallowing in the region along the Sylvian fissure. Mouth opening induced a decrease in β power, which continued until the completion of swallowing. The high γ burst of activity was focal and specific to swallowing; however, the β activities were extensive and not specific to swallowing. In the interim between voluntary and involuntary swallowing, swallowing‐related high γ power achieved its peak, and subsequently, the power decreased.InterpretationWe demonstrated three distinct activities related to mouth opening, water injection, and swallowing induced at different timings using high γ activities. The peak of high γ power related to swallowing suggests that during voluntary swallowing phases, the cortex is the main driving force for swallowing as opposed to the brain stem.

Swallowing ability and intra-oral water-retaining ability during moderate propofol sedation in healthy human volunteers: A prospective observational study.

The cough reflex or aspiration under monitored anaesthesia care might be associated with sedative-induced changes in swallowing and intra-oral water-retaining abilities. To investigate the effects of moderate propofol sedation on swallowing and intra-oral water-retaining ability. Prospective observational study. Single tertiary care centre during 2017. A total of 13 healthy adult volunteers. Volunteers in the supine position were asked to retain 10 ml of orally injected water for 5 min. After 5 minutes or when the water was spontaneously swallowed, the retention time and residual intra-oral water volume were measured. Subjects then voluntarily swallowed a further 10 ml of injected water and the residual water volume was measured. This whole process was repeated under sedation with propofol at effect-site concentrations of 0.5, 1.0 and 1.5 μg ml-1. The primary outcome was the estimated volume swallowed (swallowing volume); the secondary outcome was water retention time. Median water retention time decreased from 300 to 11 s (P < 0.001), and greater spontaneous swallowing was induced with increased propofol effect-site concentrations measuring up to 1.5 μg ml-1 (P < 0.001). The median of the estimated swallowing volumes with voluntary swallowing while awake and with all three concentrations of propofol were 9.5, 9.6, 9.6 and 9.4 ml, respectively (P = 0.805); more water remained after spontaneous swallowing than after voluntary swallowing at all concentrations. Differences in mean estimated swallowing volumes between voluntary and spontaneous swallowing were 3.4 ml (95% CI, 0.9 to 6.0, P = 0.016) for 0.5 μg ml-1, 4.1 ml (95% CI, 1.8 to 6.3, P = 0.002) for 1.0 μg ml-1 and 5.1 ml (95% CI, 3.4 to 6.8, P < 0.001) for 1.5 μg ml-1. Moderate propofol sedation decreases water-retaining ability but has no effect on voluntary swallowing. Ensuring that patients can respond under sedation may effectively prevent the unexpected cough reflex and aspiration by enabling occasional voluntary swallowing. UMIN Clinical Trials Registry identifier: UMIN000027517.

Eletromiografia de Superfície dos Músculos Masseter e Supra-Hióideos na Fase Oral da Deglutição em Adultos Saudáveis

Objective: to evaluate by means of electromyographic analysis of the masseter and suprahyoid muscles the oral phase of the swallowing of different volumes of saliva and liquid in healthy adult individuals. Material and Methods: the method consisted in analyzing samples of three swallowing trials: voluntary and single swallow of saliva (dry), voluntary and single swallow of 10 ml of water, and voluntary and single swallow of 20ml of water. Statistical analysis: Through Friedman’s ANOVA test we observed a significant variation in the medium potential of the right suprahyoid muscle (p=0.010) when compared to the left suprahyoid muscle (p=0.05). Other correlations were verified by using the Nemenyi test, the Wilcoxon test and the Spearman coefficient to support the different analyses of the results. Results: the analysis found a direct relation between the electrical activity of the masseter and suprahyoid muscles when swallowing 20 ml water as regards the highest potential values, irrespective of face side – left or right; i.e., when swallowing 20ml water, the higher the potential of one muscle group, the higher the expected value of its antagonist. Conclusion: the electromyographic behavior of the masseter and suprahyoid muscles during voluntary swallowing of saliva and two standardized liquid volumes showed that the electrical activity of the masseter muscles did not vary according to the type of swallowing.

Electroacupuncture Involved in Motor Cortex and Hypoglossal Neural Control to Improve Voluntary Swallowing of Poststroke Dysphagia Mice.

The descending motor nerve conduction of voluntary swallowing is mainly launched by primary motor cortex (M1). M1 can activate and regulate peripheral nerves (hypoglossal) to control the swallowing. Acupuncture at “Lianquan” acupoint (CV23) has a positive effect against poststroke dysphagia (PSD). In previous work, we have demonstrated that electroacupuncture (EA) could regulate swallowing-related motor neurons and promote swallowing activity in the essential part of central pattern generator (CPG), containing nucleus ambiguus (NA), nucleus of the solitary tract (NTS), and ventrolateral medulla (VLM) under the physiological condition. In the present work, we have investigated the effects of EA on the PSD mice in vivo and sought evidence for PSD improvement by electrophysiology recording and laser speckle contrast imaging (LSCI). Four main conclusions can be drawn from our study: (i) EA may enhance the local field potential in noninfarction area of M1, activate the swallowing-related neurons (pyramidal cells), and increase the motor conduction of noninfarction area in voluntary swallowing; (ii) EA may improve the blood flow in both M1 on the healthy side and deglutition muscles and relieve PSD symptoms; (iii) EA could increase the motor conduction velocity (MCV) in hypoglossal nerve, enhance the EMG of mylohyoid muscle, alleviate the paralysis of swallowing muscles, release the substance P, and restore the ability to drink water; and (iv) EA can boost the functional compensation of M1 in the noninfarction side, strengthen the excitatory of hypoglossal nerve, and be involved in the voluntary swallowing neural control to improve PSD. This research provides a timely and necessary experimental evidence of the motor neural regulation in dysphagia after stroke by acupuncture in clinic.

Effects of Carbonation and Temperature on Voluntary Swallowing in Healthy Humans.

We investigated how swallowing behaviors are affected by the temperature and carbonation of water in healthy humans. Twenty-nine healthy volunteers were instructed to drink as much natural water, carbonated water, or cider as they wanted, and we recorded the volume of solution swallowed and electromyographic (EMG) activity of the masseter and suprahyoid muscles. Sensory tests regarding the ease of holding the solution in the mouth and ease of swallowing were also performed. The volume of carbonated water swallowed was significantly lower than that of natural water and cider. The ease of holding and swallowing the solution significantly differed between solution types such that natural water was the easiest solution to hold and swallow, followed by cider and then carbonated water in both tests. EMG activity was also affected by the solution type. Masseter EMG activity was significantly lower when swallowing natural water compared with carbonated water. Suprahyoid EMG activity was significantly lower when swallowing natural water compared with carbonated water and cider. The volume of solution swallowed was significantly correlated with the ease of holding and swallowing the solution, but not with masseter or suprahyoid EMG activities. The ease of holding and swallowing the solution significantly affected masseter and suprahyoid EMG activities. The results suggested that when participants experienced difficulty holding and swallowing the solution, masseter and suprahyoid EMG activity increased. Considering our findings that mechanical stimulation with bubbles decreased the volume of solution swallowed and increased EMG activities, carbonated water swallowing may be useful in treating deglutition disorders.

Improvement of a delayed swallowing reflex following treatment for advanced head and neck cancer

BackgroundThe latency of the swallowing reflex is an important factor causing dysphagia in head and neck cancer patients. Although there are many reports comparing voluntary swallowing function before and after treatment, few studies have focused on the latency of the swallowing reflex, which is a risk factor for pneumonia due to silent aspiration. The aim of this retrospective study was to clarify the changes in the latency of the swallowing reflex before and after treatment.MethodsThe latency of the swallowing reflex was quantified using the time from the injection of 1 ml of distilled water into the pharynx through a nasal catheter to the onset of swallowing.ResultsThe latency time of the swallowing reflex was significantly decreased 3 months after treatment compared to before treatment. A significant reduction was also observed in patients with pharyngeal cancer who underwent chemoradiation therapy.ConclusionsThis retrospective study showed that a delayed swallowing reflex improved with treatment in advanced head and neck cancer patients.Trial registrationThe Institutional Review Board of Tohoku University Hospital (Number 2014–1-274).

Elicitation of the Swallowing Reflex by Esophageal Stimulation in Healthy Subjects: An Evaluation Using High-Resolution Manometry.

The purposes of this human study using high-resolution manometry were to verify whether the swallowing reflex can be evoked by intra-esophageal fluid injection and whether the reflex latency and manometric variables differ depending on the injected location, amount, or speed. Ten healthy individuals participated in this study. The tip of the intranasal catheter for injection was placed at 5cm (upper), 10cm (upper-middle), 15cm (lower-middle), or 20cm (lower) from the distal end of the upper esophageal sphincter (UES). An intra-esophageal injection of 3mL or 10mL of thickened water was administered and controlled at 3mL/s or 10mL/s. Latencies from the start of the injection to the onset of UES relaxation were compared regarding injection locations, amounts, and rates. Manometric variables of intra-esophageal injection and voluntary swallowing were compared. The latency became shorter when the upper region was injected. Latency after the 10-mL injection was shorter than that after the 3-mL injection (p < 0.01) when faster injection (10mL/s) was used. Faster injection induced shorter latency (p < 0.01) when a larger volume (10mL) was injected. Pre-maximum and post-maximum UES pressures during voluntary swallowing or during spontaneous swallowing when injecting the upper esophageal region were significantly higher than spontaneous swallowing at other regions (p < 0.01). Intra-esophageal fluid injection induces the swallowing reflex in humans. The most effective condition for inducing the swallowing reflex involved a larger fluid amount with a faster injection rate in the upper esophagus.

Self-adapting Classification System for Swallow Intention Detection in Dysphagia Therapy

Abstract In dysphagia the ability of elevating the larynx and hyoid is usually impaired. Electromyography (EMG) and Bioimpedance (BI) measurements at the neck can be used to trigger functional electrical stimulation (FES) of swallowing related muscles. The height and speed of larynx elevation can be assessed by evaluating the BI during a swallow. For the triggering of an supporting FES and for biofeedback online detection of swallow onsets is required. Patients can practice by a gamified biofeedback to swallow harder, swallow in a timely manner or to maintain the larynx elevation for a longer time period (Mendelson maneuver). The success of the stimulation and biofeedback therapy as well as the acceptance by the patient strongly depends on the precise detection of swallow onsets. We have introduced a classification algorithm based on a random forest classifier to trigger FES in phase with voluntary swallowing based on EMG and BI. Although the classification is successful in healthy subjects, difficulties appear in the utilization on some patients. The reason for this can be found in a strongly varying residual swallow activity. Usually the activity of EMG and change in BI are smaller in patients compared to healthy subjects. Thus an adaption procedure is needed, that can be easily applied. In this paper we introduce an algorithm that is capable to find an optimal classifier for a patient in terms of sensitivity. The adaption algorithm uses a small number of recorded swallow onsets of a patient at the beginning of a therapy session to evaluate different classifiers and to pick the most suitable for the treatment. The set of random forest classifiers has been trained with data from healthy subjects by step wise shifting the class weights of swallows and non-swallows, yielding classifiers with different sensitivities. The evaluation is done using data from 41 patients. It showed that the sensitivity of the classification can be increased by 4 to 6 % in average compared to fixed classifiers, but up to 66 % for individual patients. Finally, we studied the effect this adaptive classifier in triggered stimulation therapy in a single dysphagia patient. Swallowing performance was measurements during one week of therapy consisting of eleven therapy session. An improvement of 40 and 63 % in larynx elevation and speed could be observed, respectively.

Measuring dynamic Eustachian tube function using tympanometry in a pressure chamber: the effect of nasal betahistine application

To assess the effect of topical betahistine on Eustachian tube function in subjectively abnormal subjects in a hyperbaric chamber. Active and passive Eustachian tube function was examined using tympanometry in a pressure chamber. Active Eustachian tube function was tested against the negative middle ear pressure induced by increasing the chamber pressure to +3 kPa. One voluntary swallow decreased middle-ear pressure by a mean of 1.36 kPa. Passive Eustachian tube function was tested by measuring spontaneous Eustachian tube openings as the chamber pressure dropped from +10 kPa to ambient. Four distinct patterns of Eustachian tube behaviour were seen, three of which indicated Eustachian tube dysfunction. Betahistine had no positive effect on Eustachian tube opening, although previous animal studies had suggested a beneficial effect. Topical betahistine had no effect on Eustachian tube function. Combining a hyperbaric chamber with tympanometry proved ideal for evaluating Eustachian tube function.

Brain signatures associated with swallowing efficiency in older people.

Swallowing is a complex movement consisting of the sequential and orderly activation of the swallowing muscles. Neuroimaging evidence has revealed a complex cortical and subcortical representation of voluntary swallowing. The repetitive saliva swallowing test (RSST) is a convenient and simple method for assessing swallowing performance in older people. It remains unclear whether individual differences in swallowing performance are associated with variations in structural brain signatures. We aimed to investigate the association between swallowing efficiency (SWE, measured by the RSST) and gray matter volume (GMV) in healthy older adults. Forty healthy older adults (52-82 years old, 28 female) underwent T1-weighted magnetic resonance imaging (MRI) and clinical assessments of SWE, stimulated/unstimulated salivary flow rate, masticatory cycle, and walking speed. GMV was quantified using a voxel-based morphometry (VBM) approach based on the MRI data. SWE was significantly negatively correlated with age. The association between SWE and hand grip strength, but not the other clinical metrics, was statistically significant. The GMV of the left posterior cerebellum (from cerebellum crus to lobule VIII) was significantly positively correlated with SWE, as evidenced by the results of whole-brain and cerebellum-specific VBM analyses. SWE was significantly positively correlated with the cerebellar volume in the region-of-interest analyses based on automated segmentation. In healthy older adults, swallowing efficiency was positively correlated with cerebellar GMV. The findings suggested that in older people, structural variations of the brain may play a key role in individual differences in swallowing performance.