Submental transcutaneous electrical stimulation can impact the timing of laryngeal vestibule closure.

BACKGROUND: Laryngeal vestibule closure (LVC) is one of the critical airway protection mechanisms during swallowing. LVC timing impairments during swallowing are among the common causes of airway invasion in patients with dysphagia. OBJECTIVES: To understand whether using submental transcutaneous electrical stimulation (TES) with varying pulse durations can impact the LVC reaction time (LVCrt) and LVC duration (LVCd) measures in healthy adults. METHODS: Twenty-six healthy adults underwent three TES conditions while receiving three trials of 10 ml pureed: no TES, TES with short pulse duration (300 µs) and TES with long pulse durations(700 µs). Two pairs of electrodes were placed diagonally on the submental area. For each active TES condition, the stimulation was increased up to the participant's self-identified maximum tolerance. Each swallow trial was recorded using videofluoroscopic swallowing study. All data were extracted and analysed offline using VideoPad Video Editor program. RESULTS: Submental TES reduced LVCrt during swallowing [F (2, 46) = 7.234, p < .007, ηp2 = .239] but had no significant impact on LVCd [F (2, 50) = .1.118, p < .335, ηp2 = .043]. Furthermore, pulse duration had no distinguished impact on any LVC timing measures. CONCLUSION: Transcutaneous electrical stimulation may benefit patients with dysphagia who suffer from delayed LVC during swallowing. Future studies should seek whether the same physiologic effect can be observed in patients with dysphagia.

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

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

The effect of galvanization and potassium iodide iontophoresis of the throat and larynx on thyroid parameters: a randomized controlled trial.

Few studies have assessed the application and side effects of potassium iodide (KI) iontophoresis. Using a double-blinded randomized controlled trial with a 1:1 parallel-group, we investigated the effect of galvanization and the KI iontophoresis in the throat and larynx on three thyroid parameters. A total of 50 healthy volunteers with normal TSH, FT3, and FT4 levels and lacking focal changes in the thyroid ultrasonography were subjected to 10 electrotherapy treatments. The TSH, FT3, and FT4 levels were determined prior to the 10 electrotherapeutic treatments (T1), 2-weeks after treatment (T2) and 6-months after treatment (T3). At T2 and T3, both groups had normal levels of TSH, FT3, and FT4. Regarding the change of TSH, FT3, and FT4 levels between T1 vs. T2 and T1 vs. T3, no significant differences between the galvanization and iontophoresis groups were found. However, both groups had lower levels of all three hormones at T3. Together, these data indicate that KI iontophoresis does not affect thyroid hormone levels in the short- nor long-term. Additional follow-up studies with larger groups are required to better confirm the safety of galvanization and iontophoresis procedures in the pharynx and larynx.Trial registration ClinicalTrials.gov (NCT04013308; URL: www.clinicaltrials.gov ). Day of first registration 09/07/2019.

Cortical reorganization following auditory deprivation predicts cochlear implant performance in postlingually deaf adults.

Long-term hearing loss in postlingually deaf (PD) adults may lead to brain structural changes that affect the outcomes of cochlear implantation. We studied 94 PD patients who underwent cochlear implantation and 37 patients who were MRI-scanned within 2 weeks after the onset of sudden hearing loss and expected with minimal brain structural changes in relation to deafness. Compared with those with sudden hearing loss, we found lower gray matter (GM) probabilities in bilateral thalami, superior, middle, inferior temporal cortices as well as the central cortical regions corresponding to the movement and sensation of the lips, tongue, and larynx in the PD group. Among these brain areas, the GM in the middle temporal cortex showed negative correlation with disease duration, whereas the other areas displayed positive correlations. Left superior, middle temporal cortical, and bilateral thalamic GMs were the most accurate predictors of post-cochlear implantation word recognition scores (mean absolute error [MAE] = 10.1, r = .82), which was superior to clinical variables used (MAE: 12.1, p < .05). Using the combined brain morphological and clinical features, we achieved the best prediction of the outcome (MAE: 8.51, r = .90). Our findings suggest that the cross-modal plasticity allowing the superior temporal cortex and thalamus to process other modal sensory inputs reverses the initially lower volume when deafness becomes persistent. The middle temporal cortex processing higher-level language comprehension shows persistent negative correlations with disease duration, suggesting this area's association with degraded speech comprehensions due to long-term deafness. Morphological features combined with clinical variables might play a key role in predicting outcomes of cochlear implantation.

Adjustment of Vocal Tract Shape via Biofeedback: Influence on Vowels.

The study assessed 30 nonprofessional singers to evaluate the effects of vocal tract shape adjustment via increased resonance toward an externally applied sinusoidal frequency of 900 Hz without phonation. The amplification of the sound wave was used as biofeedback signal and the intensity and the formant position of the basic vowels /a/, /e/, /i/, /o/, and /u/ were compared before and after a vocal tract adjustment period. After the adjustment period, the intensities for all vowels increased and the measured changes correlated with the participants' self-perception.The diferences between the second formant position of the vowels and the applied frequency influences the changes in amplitude and in formant frequencies. The most significant changes in formant frequency occurred with vowels that did not include a formant frequency of 900 Hz, while the increase in amplitude was the strongest for vowels with a formant frequency of about 900 Hz.

Effects of electromyographic biofeedback as an adjunctive therapy in the treatment of swallowing disorders: a systematic review of the literature.

PURPOSE: To describe the primary effects of electromyographic biofeedback therapy on swallowing via a systematic review. METHODS: A blind search was carried out by two researchers in the PubMed and Bireme platforms and in the Medline, Lilacs, SciELO, PsycINFO, CINAHL, and Web of Science databases, and the journal articles identified therein were evaluated for inclusion in the study. Original articles associated with the theme were selected with no population-, region-, or language-associated limits. A protocol was created for this study with the following points: author, year, place, number and characteristics of participants, activities evaluated, instruments used, and main results. The PEDro scale was used to analyze the quality of the studies. RESULTS: Among the 686 articles identified in the combined searches, 566 were duplicates. A total of 65 articles were discarded after the title and abstract were read, and a further 29 articles were discarded after the full text was read, yielding a total of six articles for inclusion. In summary, the results lead us to believe that positive effects on the laryngeal lifting capacity, improved swallowing functions, and increased excursion and maximal elevation of the hyoid bone, may be directly related to this method of therapy. CONCLUSIONS: Adjunctive therapeutic protocols with biofeedback electromyography exert positive effects on swallowing function.

Intermittent theta burst stimulation over right somatosensory larynx cortex enhances vocal pitch-regulation in nonsingers.

While the significance of auditory cortical regions for the development and maintenance of speech motor coordination is well established, the contribution of somatosensory brain areas to learned vocalizations such as singing is less well understood. To address these mechanisms, we applied intermittent theta burst stimulation (iTBS), a facilitatory repetitive transcranial magnetic stimulation (rTMS) protocol, over right somatosensory larynx cortex (S1) and a nonvocal dorsal S1 control area in participants without singing experience. A pitch-matching singing task was performed before and after iTBS to assess corresponding effects on vocal pitch regulation. When participants could monitor auditory feedback from their own voice during singing (Experiment I), no difference in pitch-matching performance was found between iTBS sessions. However, when auditory feedback was masked with noise (Experiment II), only larynx-S1 iTBS enhanced pitch accuracy (50-250 ms after sound onset) and pitch stability (>250 ms after sound onset until the end). Results indicate that somatosensory feedback plays a dominant role in vocal pitch regulation when acoustic feedback is masked. The acoustic changes moreover suggest that right larynx-S1 stimulation affected the preparation and involuntary regulation of vocal pitch accuracy, and that kinesthetic-proprioceptive processes play a role in the voluntary control of pitch stability in nonsingers. Together, these data provide evidence for a causal involvement of right larynx-S1 in vocal pitch regulation during singing.

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

Purpose: Hyoid bone and laryngeal approximation aid airway protection (laryngeal vestibule closure) while moving toward their peak superior and anterior positions during swallowing. Submental surface electrical stimulation (SES) is a therapeutic technique that targets the muscles that move the hyoid bone during swallowing. It is unknown whether submental SES only increases peak hyoid bone swallowing positions but not peak laryngeal swallowing positions, which could require faster or greater laryngeal movement to achieve adequate laryngeal vestibule closure. Method: We examined the effects of submental SES on hyo-laryngeal kinematics in 30 healthy adults who swallowed 50 times using an error-based learning paradigm. Results: Submental SES did not alter any hyo-laryngeal swallowing kinematic. However, submental SES significantly changed the starting position of the hyoid bone just prior to the swallow onset (more anterior; p = .003). On average, submental SES immediately prior to swallow onset can position the hyoid approximately 20% closer to its peak swallowing point. Conclusions: These findings indicate that electrical stimulation of the agonists for hyoid movement might not alter swallowing outcomes tested in this study. However, submental SES could have clinical utility by minimizing swallowing impairments related to reduced hyoid swallowing range of motion in individuals with dysphagia.

A Review of the Physiological Effects and Mechanisms of Singing.

Daily experience suggests that singing can energize us and even provide a physical workout. A growing amount of evidence has been presented to support anecdotal claims of the benefits of singing on health and well-being. Singing has been shown to be related to numerous physiological changes. The cardiorespiratory system is utilized during persistent singing training, resulting in enhanced respiratory muscles and an optimized breathing mode. In addition, singing can also cause changes in neurotransmitters and hormones, including the upregulation of oxytocin, immunoglobulin A, and endorphins, which improves immune function and increases feelings of happiness. This review is organized by respiratory, circulatory, and hormonal changes that are collectively a part of singing in a healthy population. The various studies are discussed with the intention of helping researchers and clinicians realize the potential benefit of singing and provide a clinical option as an adjunct therapy for a given situation. Better understanding of physiological mechanisms will lay a solid theoretical foundation for singing activities and will present important implications for further study. Evaluations of existing research and recommendations for future research are given to promote the scale and duration to better demonstrate the effectiveness of singing before it can be recommended in clinical guidelines and satisfy criteria for funding by commissioners of health and social care.

Consequences of maternal omega-3 polyunsaturated fatty acid supplementation on respiratory function in rat pups.

KEY POINTS: Incomplete development of the neural circuits that control breathing contributes to respiratory disorders in pre-term infants. Manifestations include respiratory instability, prolonged apnoeas and poor ventilatory responses to stimuli. Based on evidence suggesting that omega-3 polyunsaturated fatty acids (n-3 PUFA) improves brain development, we determined whether n-3 PUFA supplementation (via the maternal diet) improves respiratory function in 10-11-day-old rat pups. n-3 PUFA treatment prolonged apnoea duration but augmented the relative pulmonary surface area and the ventilatory response to hypoxia. During hypoxia, the drop in body temperature measured in treated pups was 1 °C less than in controls. n-3 PUFA treatment also reduced microglia cell density in the brainstem. Although heterogeneous, the results obtained in rat pups constitute a proof of concept that n-3 PUFA supplementation can have positive effects on neonatal respiration. This includes a more sustained hypoxic ventilatory response and a decreased respiratory inhibition during laryngeal chemoreflex. ABSTRACT: Most pre-term infants present respiratory instabilities and apnoeas as a result of incomplete development of the neural circuits that control breathing. Because omega-3 polyunsaturated fatty acids (n-3 PUFA) benefit brain development, we hypothesized that n-3 PUFA supplementation (via the maternal diet) improves respiratory function in rat pups. Pups received n-3 PUFA supplementation from an enriched diet (13 g kg-1 of n-3 PUFA) administered to the mother from birth until the experiments were performed (postnatal days 10-11). Controls received a standard diet (0.3 g kg-1 of n-3 PUFA). Breathing was measured in intact pups at rest and during hypoxia (FiO2  = 0.12; 20 min) using whole body plethysmography. The duration of apnoeas induced by stimulating the laryngeal chemoreflex (LCR) was measured under anaesthesia. Lung morphology was compared between groups. Maternal n-3 PUFA supplementation effectively raised n-3 PUFA levels above control levels both in the blood and brainstem of pups. In intact, resting pups, n-3 PUFA increased the frequency and duration of apnoeas, especially in females. During hypoxia, n-3 PUFA supplemented pups hyperventilated 23% more than controls; their anapyrexic response was 1 °C less than controls. In anaesthetized pups, n-3 PUFA shortened the duration of LCR-induced apnoeas by 32%. The relative pulmonary surface area of n-3 PUFA supplemented pups was 12% higher than controls. Although n-3 PUFA supplementation augments apnoeas, there is no clear evidence of deleterious consequences on these pups. Based on the improved lung architecture and responses to respiratory challenges, this neonatal treatment appears to be beneficial to the offspring. However, further experiments are necessary to establish its overall safety.