Glossopharyngeal evoked potentials in normal subjects following mechanical stimulation of the anterior faucial pillar

Electrophysiological Measures of Swallowing Functions: A Systematic Review

The purpose of this systematic review was to examine the application of event-related potentials (ERPs) to investigate neural processes of swallowing functions in adults with and without dysphagia. Computerized literature searches were performed from three search engines. Studies were screened using Covidence (Cochrane tool) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement standards (PRISMA-2009). A total of 759 studies were initially retrieved, of which 12 studies met inclusion criteria. Electrophysiological measures assessing swallowing functions were identified in two major ERP categories: (1) sensory potentials and (2) pre-motor potentials. Approximately 80% of eligible studies demonstrated strong methodological quality, although most employed a case series or case-control study design. Pharyngeal sensory-evoked potentials (PSEPs) were used to assess pharyngeal afferent cortical processing. The temporal sequence of the PSEP waveforms varied based on the sensory stimuli. PSEPs were delayed with localized scalp maps in patients with dysphagia as compared to healthy controls. The pre-motor ERPs assessed the cortical substrates involved in motor planning for swallowing, with the following major neural substrates identified: pre-motor cortex, supplementary motor area, and primary sensorimotor cortex. The pre-motor ERPs differed in amplitude for the swallow task (saliva versus liquid swallow), and the neural networks differed for cued versus non-cued task of swallowing suggesting differences in cognitive processes. This systematic review describes the application of electrophysiological measures to assess swallowing function and the promising application for furthering understanding of the neural substrates of swallowing. Standardization of protocols for use of electrophysiological measures to examine swallowing would allow for aggregation of study data to inform clinical practice for dysphagia rehabilitation.

Big Data Recommendation Research Based on Travel Consumer Sentiment Analysis

More and more tourists are sharing their travel feelings and posting their real experiences on the Internet, generating tourism big data. Online travel reviews can fully reflect tourists’ emotions, and mining and analyzing them can provide insight into the value of them. In order to analyze the potential value of online travel reviews by using big data technology and machine learning technology, this paper proposes an improved support vector machine (SVM) algorithm based on travel consumer sentiment analysis and builds an Hadoop Distributed File System (HDFS) system based on Map-Reduce model. Firstly, Internet travel reviews are pre-processed for sentiment analysis of the review text. Secondly, an improved SVM algorithm is proposed based on the main features of linear classification and kernel functions, so as to improve the accuracy of sentiment word classification. Then, HDFS data nodes are deployed on the basis of Hadoop platform with the actual tourism application context. And based on the Map-Reduce programming model, the map function and reduce function are designed and implemented, which greatly improves the possibility of parallel processing and reduces the time consumption at the same time. Finally, an improved SVM algorithm is implemented under the built Hadoop platform. The test results show that online travel reviews can be an important data source for travel big data recommendation, and the proposed method can quickly and accurately achieve travel sentiment classification.

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.

Central Nervous System Control of Voice and Swallowing

This review of the central nervous control systems for voice and swallowing has suggested that the traditional concepts of a separation between cortical and limbic and brain stem control should be refined and be more integrative. For voice production, a separation of the nonhuman vocalization system from the human learned voice production system has been posited based primarily on studies of nonhuman primates. However, recent humans studies of emotionally based vocalizations and human volitional voice production have shown more integration between these two systems than previously proposed. Recent human studies have shown that reflexive vocalization as well as learned voice production not involving speech involve a common integrative system. However, recent studies of nonhuman primates have provided evidence that some cortical activity vocalization and cortical changes occur with training during vocal behavior. For swallowing, evidence from the macaque and functional brain imaging in humans indicates that the control for the pharyngeal phase of swallowing is not primarily under brain stem mechanisms as previously proposed. Studies suggest that the initiation and patterning of swallowing for the pharyngeal phase is also under active cortical control for both spontaneous as well as volitional swallowing in awake humans and nonhuman primates.

Peak morphology and scalp topography of the pharyngeal sensory-evoked potential

The initiation of the pharyngeal stage of swallowing is dependent upon sensory input to the brainstem and cortex. The event-related evoked potential provides a measure of neuronal electrical activity as it relates to a specific stimulus. Air-puff stimulation to the posterior pharyngeal wall produces a sensory-evoked potential (PSEP) waveform. The goal of this study was to characterize the scalp topography and morphology for the component peaks of the PSEP waveform. Twenty-five healthy men and women served as research participants. PSEPs were measured via a 32-electrode cap (10-20 system) connected to SynAmps2 Neuroscan EEG System. Air puffs were delivered directly to the oropharynx using a thin polyethylene tube connected to a flexible laryngoscope. The PSEP waveform is characterized by four early- and mid-latency component peaks: an early positivity (P1) and negativity (N1), followed by a mid-latency positivity (P2) and negativity (N2). The early positive peak P1 is localized bilaterally to the lateral parietal scalp, the N1 medially in the frontoparietal region, and the P2 and N2 with diffuse scalp locations. Somatosensory and premotor regions are possible anatomical correlates of peak locations. Based on the latencies of the peaks, they are likely analogous to somatosensory- and respiratory-related evoked potential peaks.

Sensory stimulation activates both motor and sensory components of the swallowing system

Volitional swallowing in humans involves the coordination of both brainstem and cerebral swallowing control regions. Peripheral sensory inputs are necessary for safe and efficient swallowing, and their importance to the patterned components of swallowing has been demonstrated. However, the role of sensory inputs to the cerebral system during volitional swallowing is less clear. We used four conditions applied during functional magnetic resonance imaging to differentiate between sensory, motor planning, and motor execution components for cerebral control of swallowing. Oral air pulse stimulation was used to examine the effect of sensory input, covert swallowing was used to engage motor planning for swallowing, and overt swallowing was used to activate the volitional swallowing system. Breath-holding was also included to determine whether its effects could account for the activation seen during overt swallowing. Oral air pulse stimulation, covert swallowing and overt swallowing all produced activation in the primary motor cortex, cingulate cortex, putamen and insula. Additional regions of the swallowing cerebral system that were activated by the oral air pulse stimulation condition included the primary and secondary somatosensory cortex and thalamus. Although air pulse stimulation was on the right side only, bilateral cerebral activation occurred. On the other hand, covert swallowing minimally activated sensory regions, but did activate the supplementary motor area and other motor regions. Breath-holding did not account for the activation during overt swallowing. The effectiveness of oral-sensory stimulation for engaging both sensory and motor components of the cerebral swallowing system demonstrates the importance of sensory input in cerebral swallowing control.

Swallowing and dysphagia rehabilitation: translating principles of neural plasticity into clinically oriented evidence

PURPOSE

This review presents the state of swallowing rehabilitation science as it relates to evidence for neural plastic changes in the brain. The case is made for essential collaboration between clinical and basic scientists to expand the positive influences of dysphagia rehabilitation in synergy with growth in technology and knowledge. The intent is to stimulate thought and propose potential research directions.

METHOD

A working group of experts in swallowing and dysphagia reviews 10 principles of neural plasticity and integrates these advancing neural plastic concepts with swallowing and clinical dysphagia literature for translation into treatment paradigms. In this context, dysphagia refers to disordered swallowing associated with central and peripheral sensorimotor deficits associated with stroke, neurodegenerative disease, tumors of the head and neck, infection, or trauma.

RESULTS AND CONCLUSIONS

The optimal treatment parameters emerging from increased understanding of neural plastic principles and concepts will contribute to evidence-based practice. Integrating these principles will improve dysphagia rehabilitation directions, strategies, and outcomes. A strategic plan is discussed, including several experimental paradigms for the translation of these principles and concepts of neural plasticity into the clinical science of rehabilitation for oropharyngeal swallowing disorders, ultimately providing the evidence to substantiate their translation into clinical practice.

Estimulação mecânico-térmica dos pilares palatoglosso

RACIONAL: Os pilares palatoglosso foram admitidos como a principal sede dos receptores responsáveis por iniciar a fase faríngea da deglutição. Essa fase reflexa iniciar-se-ia em resposta ao estímulo produzido pelo progresso do bolo e da língua em sentido posterior. Esses conceitos deram base à manobra mecânico-térmica que visa estimular os receptores desses pilares, produzindo respostas motoras capazes de potencializar a recuperação da função faríngea comprometida. O conceito de possível resposta motora ao estímulo desses pilares, embora comum, não é unanimemente aceito. OBJETIVO: Verificar as possíveis respostas motoras produzidas pelo estímulo mecânico- térmico sobre os pilares palatoglosso. MÉTODOS: Por entender que indivíduos sadios são capazes de prover respostas reflexas mais efetivas do que as que seriam obtidas em pacientes, avaliaram-se 51 voluntários adultos sadios de ambos os sexos reproduzindo o estímulo sobre os pilares, usando sonda metálica de ponta romba resfriada em água mantida a 10°C. RESULTADOS E CONSIDERAÇÕES: O estudo mostrou que o estímulo mecânico-térmico sobre os pilares não foi capaz de produzir qualquer resposta motora envolvida na dinâmica da fase faríngea da deglutição. É possível que as respostas contráteis observadas em alguns estudos devam-se ao reflexo de gag inadequadamente interpretado ou a contrações voluntárias inconscientes por esforço de manutenção da abertura da boca e externalização da língua durante a exposição dos pilares para execução da manobra de estimulação mecânico-térmica.

Electric stimulation approaches to the restoration and rehabilitation of swallowing: a review

In recent years, there has been a proliferation of interest in the use of electric stimulation for the treatment of swallowing disorders. This review explores both the rationale and existing evidence for electric stimulation approaches to swallowing rehabilitation. Although this is an exciting area of research which holds promise for future clinically relevant technology and/or therapy, a critical analysis of the existing literature will be presented to support the argument that implementation of electric stimulation in clinical swallowing rehabilitation settings still remains pre-mature.

Deglutitive laryngeal closure in stroke patients

BACKGROUND

Dysphagia has been reported in up to 70% of patients with stroke, predisposing them to aspiration and pneumonia. Despite this, the mechanism for aspiration remains unclear.

AIMS

To determine the relationship between bolus flow and laryngeal closure during swallowing in patients with stroke and to examine the sensorimotor mechanisms leading to aspiration.

METHODS

Measures of swallowing and bolus flow were taken from digital videofluoroscopic images in 90 patients with stroke and 50 healthy adults, after repeated volitional swallows of controlled volumes of thin liquid. Aspiration was assessed using a validated Penetration-Aspiration Scale. Oral sensation was also measured by electrical stimulation at the faucial pillars.

RESULTS

After stroke, laryngeal ascent was delayed (mean (standard deviation (SD)) 0.31 (0.06) s, p<0.001), resulting in prolongation of pharyngeal transit time (1.17 (0.07) s, p<0.001) without a concomitant increase in laryngeal closure duration (0.84 (0.04) s, p = 0.9). The delay in laryngeal elevation correlated with both the severity of aspiration (r = 0.5, p<0.001) and oral sensation (r = 0.5, p<0.001).

CONCLUSIONS

After stroke, duration of laryngeal delay and degree of sensory deficit are associated with the severity of aspiration. These findings indicate a role for sensorimotor interactions in control of swallowing and have implications for the assessment and management of dysphagia after stroke.

Deglutitive laryngeal closure in stroke patients

BACKGROUND

Dysphagia has been reported in up to 70% of patients with stroke, predisposing them to aspiration and pneumonia. Despite this, the mechanism for aspiration remains unclear.

AIMS

To determine the relationship between bolus flow and laryngeal closure during swallowing in patients with stroke and to examine the sensorimotor mechanisms leading to aspiration.

METHODS

Measures of swallowing and bolus flow were taken from digital videofluoroscopic images in 90 patients with stroke and 50 healthy adults, after repeated volitional swallows of controlled volumes of thin liquid. Aspiration was assessed using a validated Penetration-Aspiration Scale. Oral sensation was also measured by electrical stimulation at the faucial pillars.

RESULTS

After stroke, laryngeal ascent was delayed (mean (standard deviation (SD)) 0.31 (0.06) s, p<0.001), resulting in prolongation of pharyngeal transit time (1.17 (0.07) s, p<0.001) without a concomitant increase in laryngeal closure duration (0.84 (0.04) s, p = 0.9). The delay in laryngeal elevation correlated with both the severity of aspiration (r = 0.5, p<0.001) and oral sensation (r = 0.5, p<0.001).

CONCLUSIONS

After stroke, duration of laryngeal delay and degree of sensory deficit are associated with the severity of aspiration. These findings indicate a role for sensorimotor interactions in control of swallowing and have implications for the assessment and management of dysphagia after stroke.

Oropharyngeal stimulation with air-pulse trains increases swallowing frequency in healthy adults

This study sought to determine whether air-pulse trains delivered to the peritonsillar area would facilitate swallowing in healthy subjects. Trains of unilateral or bilateral air pulses were delivered to the peritonsillar area via tubing embedded in a dental splint, while swallows were simultaneously identified from their associated laryngeal and respiratory movements. Results from four subjects indicated that oropharyngeal air-pulse stimulation evoked an irrepressible urge to swallow, followed by an overt swallow as verified by laryngeal and respiratory movements. Moreover, air-pulse stimulation was associated with a significant increase in swallowing frequency. Mean latency of swallowing following bilateral stimulation tended to be less than the latency of swallowing following unilateral stimulation. These findings in healthy adults suggest the possibility that oropharyngeal air-pulse stimulation may have clinical utility in dysphagic individuals.

Glossopharyngeal nerve evoked potentials after stimulation of the posterior part of the tongue in dogs

OBJECTIVE

Lower cranial nerve palsy is one of the most critical complications after posterior fossa surgery. However, no established monitoring procedures exist for glossopharyngeal nerve function. Therefore, glossopharyngeal nerve evoked potentials after stimulation of the posterior part of the tongue in dogs was studied to analyze whether glossopharyngeal nerve compound action potentials and evoked potentials are useful in the intraoperative monitoring of patients undergoing brainstem and cerebellopontine angle surgery.

METHODS

Glossopharyngeal nerve action potentials and cortical potentials were evoked by stimulating the posterior part of the tongue in mongrel dogs. The potentials were evoked by supramaximal constant current electrical stimuli delivered with bipolar stainless steel needle electrodes and recorded with silver ball electrodes.

RESULTS

Compound nerve action potentials were recorded from the exposed intracranial portion of the glossopharyngeal nerve. The latency of the initial negative peak of the action potentials was 2.8 +/- 0.6 milliseconds (mean +/- standard deviation; n = 17). Evoked cortical potentials were recorded on the coronal gyrus by stimulating the contralateral side. The latencies of the initial positive peak and negative peak were 20.1 +/- 3.7 and 35.7 +/- 8.2 milliseconds, respectively (n = 6). Ipsilateral tongue stimulation elicited biphasic evoked potentials on the coronal gyrus, which had small amplitudes and delayed latencies. Both compound nerve action potentials and cortical evoked potentials disappeared after sectioning of the glossopharyngeal nerve.

CONCLUSION

The glossopharyngeal nerve action potentials and cortical potentials elicited by the stimulation of the posterior one-third of the tongue can be recorded. These evoked potentials represent a new means for intraoperative monitoring of patients undergoing surgery in the brainstem via the cerebellopontine angle, which involves the lower cranial nerves.

Laryngeal evoked brainstem responses in humans: a preliminary study

Laryngeal evoked brainstem responses (LBRs) were recorded in normal human subjects in an attempt to develop a central laryngeal function test and enhance our understanding of neurolaryngologic disorders. The results showed that the human LBR consists of five positive peaks and five negative peaks reproducible within 10 ms after a vibratory stimulation to the superior laryngeal nerve (SLN). The waveform reproducibility was verified by blocking the SLN and topically anesthetizing the hypopharyngeal cavity. The morphology and latency of peak 5 were similar to results obtained in animal LBR experiments. It was concluded that a vibratory stimulation to the SLN was a noninvasive method to elicit far-field potentials from the central laryngeal pathway. These findings encourage further effort to establish normative data and explore clinical correlations.

The effects of cold, touch, and chemical stimulation of the anterior faucial pillar on human swallowing

Cold stimulation of the oropharyngeal mucosa, including the faucial pillar region, is used a specific technique for the treatment of swallowing disorders. The physiological mechanisms underpinning this clinical technique are unclear. Thermal (cold), chemical (saline, glucose and water), mechanical (light touch) and feigned stimulation of the faucial pillar were assessed for their effects on the latency to swallow and the repetitive frequency of swallowing. There was no significant difference between these variables following light stimulation of the faucial pillar with a metal probe warmed to body temperature compared with feigned stimulation. However, cold touch stimulation evoked a significant increase in swallowing latency and repetitive frequency compared to feigned stimulation. The results suggest the existence of thermo-sensitive receptors in the faucial pillars that evoke swallowing when stimulated by cold touch. The clinical and physiological importance of these findings are discussed.