Esophageal Phase Of Swallowing Research Articles

Coordination of Pharyngeal and Esophageal Phases of Swallowing.

Although swallowing has been reviewed extensively, the coordination of the phases of swallowing have not. The phases are controlled by the brainstem, but peripheral factors help coordinate the phases. The occurrence, magnitude, and duration of esophageal phase depends upon peripheral feedback activated by the bolus. The esophageal phase does not occur without peripheral feedback from the esophagus. This feedback is mediated by esophageal slowly-adapting mucosal tension receptors through the recurrent and superior laryngeal nerves. A similar reflex mediated by the same peripheral pathway is the activation of swallowing by stimulation of the cervical esophagus. This reflex occurs primarily in human infants and animals, and this reflex may be important for protecting against aspiration after esophago-pharyngeal reflux. Not only are there inter-phase excitatory processes, but also inhibitory processes. A significant inhibitory process is deglutitive inhibition. When one swallows faster than peristalsis ends, peristalsis is inhibited by the new pharyngeal phase. This process prevents the ongoing esophageal peristaltic wave from blocking the bolus being pushed into the esophagus by the new wave. The esophageal phase returns during the last swallow of the sequence. This process is probably mediated by mucosal tension receptors through the superior laryngeal nerves. A similar reflex exists, the pharyngo-esophageal inhibitory reflex, but studies indicate that it is controlled by a different neural pathway. The pharyngo-esophageal inhibitory reflex is mediated by mucosal tension receptors through the glossopharyngeal nerve. In summary, there are significant peripheral processes that contribute to swallowing, whereby one phase of swallowing significantly affects the other.

Dysphagia, reflux and related sequelae due to altered physiology in scleroderma.

Systemic sclerosis is a connective tissue disease that presents with significant gastrointestinal involvement, commonly in the esophagus. Dysphagia is a common clinical manifestation of systemic sclerosis and is strongly related to esophageal dysmotility. However, there are multiple other contributing factors in each step in the physiology of swallowing that may contribute to development of severe dysphagia. The oral phase of swallowing may be disrupted by poor mastication due to microstomia and poor dentition, as well as by xerostomia. In the pharyngeal phase of swallowing, pharyngeal muscle weakness due to concurrent myositis or cricopharyngeal muscle tightening due to acid reflux can cause disturbance. The esophageal phase of swallowing is most commonly disturbed by decreased peristalsis and esophageal dysmotility. However, it can also be affected by obstruction from chronic reflux changes, pill-induced esophagitis, or Candida esophagitis. Other contributing factors to dysphagia include difficulties in food preparation and gastroparesis. Understanding the anatomy and physiology of swallowing and evaluating systemic sclerosis patients presenting with dysphagia for disturbances in each step can allow for development of better treatment plans to improve dysphagia and overall quality of life.

Functional endoscopy in neurogenic dysphagia: a feasibility study focusing on the esophageal phase of swallowing.

Background and study aims Due to demographic transition, neurogenic dysphagia has become an increasingly recognized problem. Patients suffering from dysphagia often get caught between different clinical disciplines. In this study, we implemented a defined examination protocol for evaluating the whole swallowing process by functional endoscopy. Special focus was put on the esophageal phase of swallowing. Patients and methods This prospective observational multidisciplinary study evaluated 31 consecutive patients with suspected neurogenic dysphagia by transnasal access applying an ultrathin video endoscope. Thirty-one patients with gastroesophageal reflux symptoms were used as a control group. We applied a modified approach including standardized endoscopic positions to compare our findings with fiberoptic endoscopic evaluation of swallowing and high-resolution manometry. The primary outcome measure was feasibility of functional endoscopy. Secondary outcome measures were adverse events (AEs), tolerability, and pathologic endoscopic findings. Results Functional endoscopy was successfully performed in all patients. No AEs were recorded. A variety of disorders were documented by functional endoscopy: incomplete or delayed closure of the upper esophageal sphincter in retroflex view, clearance disturbance of tubular esophagus, esophageal hyperperistalsis, and hypomotility. Analysis of results obtained with the diagnostic tools showed some discrepancies. Conclusions By interdisciplinary cooperation with additional assessment of the esophageal phase of deglutition using the innovative method of functional endoscopy, the diagnosis of neurogenic disorders including dysphagia may be significantly improved, leading to a better clinical understanding of complex dysfunctional patterns. To the best of our knowledge, this is the first study to show that a retroflex view of the ultrathin video endoscope within the esophagus can be safely performed. [NCT01995929]

Dysphagia

Dysphagia may be oropharyngeal or esophageal. Evaluation is described, including a thorough dysphagia history of associated painful swallowing, location, solids versus liquids, intermittent versus progressive, acute versus gradual onset, and associated symptoms such as weight loss. Physical examination and key diagnostic tests are also reviewed. The evidence-based management of various etiologies of esophageal dysphagia are summarized. Motor disorders described include achalasia, the other primary esophageal motility disorders, and the most common secondary esophageal motility disorders. Esophageal diverticulae are also reviewed in this section. Mechanical esophageal obstruction is presented, including discussions of esophageal webs, rings, peptic stricture, and cancer. Important inflammatory and infectious causes of dysphagia are described, including caustic ingestion, eosinophilic esophagitis, and esophageal infections. The oral phases of liquid and solid swallowing are presented, as are the pharyngeal and esophageal phases of swallowing. Figures show the results of several diagnostic tests and other conditions, including pharyngeoesophageal diverticulum, giant epiphrenic diverticulum, Schatzki ring, and midesophageal squamous cell carcinoma. A flowchart outlines evaluation and management of dysphagia. This review contains 13 figures, 12 tables, and 68 references. Keyword: Esophageal cancer, Achalasia, Diffuse esophageal spasm, Esophageal ring, Peptic esophagitis, Eosinophilic esophagitis, Scleroderma, Esophageal stricture, Chagas disease, Stroke

Dysphagia

Dysphagia may be oropharyngeal or esophageal. Evaluation is described, including a thorough dysphagia history of associated painful swallowing, location, solids versus liquids, intermittent versus progressive, acute versus gradual onset, and associated symptoms such as weight loss. Physical examination and key diagnostic tests are also reviewed. The evidence-based management of various etiologies of esophageal dysphagia are summarized. Motor disorders described include achalasia, the other primary esophageal motility disorders, and the most common secondary esophageal motility disorders. Esophageal diverticulae are also reviewed in this section. Mechanical esophageal obstruction is presented, including discussions of esophageal webs, rings, peptic stricture, and cancer. Important inflammatory and infectious causes of dysphagia are described, including caustic ingestion, eosinophilic esophagitis, and esophageal infections. The oral phases of liquid and solid swallowing are presented, as are the pharyngeal and esophageal phases of swallowing. Figures show the results of several diagnostic tests and other conditions, including pharyngeoesophageal diverticulum, giant epiphrenic diverticulum, Schatzki ring, and midesophageal squamous cell carcinoma. A flowchart outlines evaluation and management of dysphagia. This review contains 13 figures, 12 tables, and 68 references. Keyword: Esophageal cancer, Achalasia, Diffuse esophageal spasm, Esophageal ring, Peptic esophagitis, Eosinophilic esophagitis, Scleroderma, Esophageal stricture, Chagas disease, Stroke

Swall-E: A robotic in-vitro simulation of human swallowing.

Swallowing is a complex physiological function that can be studied through medical imagery techniques such as videofluoroscopy (VFS), dynamic magnetic resonance imagery (MRI) and fiberoptic endoscopic evaluation of swallowing (FEES). VFS is the gold standard although it exposes the subjects to radiations. In-vitro modeling of human swallowing has been conducted with limited results so far. Some experiments were reported on robotic reproduction of oral and esophageal phases of swallowing, but high fidelity reproduction of pharyngeal phase of swallowing has not been reported yet. To that end, we designed and developed a robotic simulator of the pharyngeal phase of human swallowing named Swall-E. 17 actuators integrated in the robot enable the mimicking of important physiological mechanisms occurring during the pharyngeal swallowing, such as the vocal fold closure, laryngeal elevation or epiglottis tilt. Moreover, the associated computer interface allows a control of the actuation of these mechanisms at a spatio-temporal accuracy of 0.025 mm and 20 ms. In this study preliminary experiments of normal pharyngeal swallowing simulated on Swall-E are presented. These experiments show that a 10 ml thick bolus can be swallowed by the robot in less than 1 s without any aspiration of bolus material into the synthetic anatomical laryngo-tracheal conduit.

Oropharyngeal Deglutition Characterization in Multiple Sclerosis

Introduction: Multiple sclerosis is a disease with neurogenic disease progression distinct authors reported the presence of oropharyngeal dysphagia, which usually involve the oral phase, pharyngeal, and esophageal phases of swallowing.

Tu1965 Role of Peripheral Reflexes in Initiation of the Esophageal Phase of Swallowing

Tu1965 Role of Peripheral Reflexes in Initiation of the Esophageal Phase of Swallowing

EFFECT OF A BITTER BOLUS ON ORAL, PHARYNGEAL AND ESOPHAGEAL TRANSIT OF HEALTHY SUBJECTS

During swallowing, boluses stimulate sensory receptors of the oral, pharyngeal, laryngeal, and esophageal regions. Sweet and tasteless foods are more acceptable for swallowing than bitter foods. A bitter bolus is unpleasant for most subjects. Our hypothesis was that the ingestion of a bitter bolus might alter the oral behavior, pharyngeal and esophageal transit when compared to a sweet bolus. To evaluate whether the bitter taste of a liquid bolus causes alteration on oral, pharyngeal and/or esophageal transit in normal subjects in comparison with sweet bolus.' Scintigraphic evaluation of oral, pharyngeal and esophageal transit was performed in 43 asymptomatic subjects, 22 women and 21 men, ages 23-71 years, without problems with the ingestion of liquid and solid foods, and without digestive, cardiac or neurologic diseases. Each subject swallowed in random sequence and at room temperature 5 mL of a liquid bolus with bitter taste, prepared with 50 mL of water with 2 g of leaves of Peumus boldus, heated until boiling (boldus tea), and 5 mL of a liquid bolus with sweet taste, prepared with 50 mL of water with 3 g of sucrose, both labeled with 37 MBq of technetium phytate (Tc99m). There was no difference between the bitter bolus and the sweet bolus in mouth, pharynx and esophageal transit and clearance duration and in the amount of residues. A bitter bolus, considered an unpleasant bolus, does not alter the duration of oral, pharyngeal and esophageal phases of swallowing, when compared with a sweet bolus, considered a pleasant bolus.

Problems in Surgical Treatment for Dysplasia in the Esophageal Phase of Swallowing

Problems in Surgical Treatment for Dysplasia in the Esophageal Phase of Swallowing

Unusual Manifestations of Bilateral Carotid Artery Dissection: Dysphagia and Hoarseness

Dissection of the carotid artery can occur intracranially or extracranially, although dissections tend to affect extracranial segments of the arteries much more commonly than intracranial segments. Carotid artery dissection (CAD) is most common in middle-aged women. Although not completely known, the main risk factors related to carotid artery dissection are genetic and environmental factors, traumatic events, cervical manipulation, migraine, recent infections, hyperhomocysteinemia, and hereditary connective tissue disorders. Although some cases of bilateral internal CAD have been reported, spontaneous bilateral dissections are rare. Prolonged hoarseness is usually due to using the voice either too much, too loudly, or improperly over an extended period of time. Disorders leading to dysphagia may affect the oral, pharyngeal, or esophageal phases of swallowing. In this study we report on a patient with bilateral CAD who presented to our clinic with dysphagia and hoarseness.

Brain Stem Control of the Phases of Swallowing

The phases of swallowing are controlled by central pattern-generating circuitry of the brain stem and peripheral reflexes. The oral, pharyngeal, and esophageal phases of swallowing are independent of each other. Although central pattern generators of the brain stem control the timing of these phases, the peripheral manifestation of these phases depends on sensory feedback through reflexes of the pharynx and esophagus. The dependence of the esophageal phase of swallowing on peripheral feedback explains its absence during failed swallows. Reflexes that initiate the pharyngeal phase of swallowing also inhibit the esophageal phase which ensures the appropriate timing of its occurrence to provide efficient bolus transport and which prevents the occurrence of multiple esophageal peristaltic events. These inhibitory reflexes are probably partly responsible for deglutitive inhibition. Three separate sets of brain stem nuclei mediate the oral, pharyngeal, and esophageal phases of swallowing. The trigeminal nucleus and reticular formation probably contain the oral phase pattern-generating neural circuitry. The nucleus tractus solitarius (NTS) probably contains the second-order sensory neurons as well as the pattern-generating circuitry of both the pharyngeal and esophageal phases of swallowing, whereas the nucleus ambiguus and dorsal motor nucleus contain the motor neurons of the pharyngeal and esophageal phases of swallowing. The ventromedial nucleus of the NTS may govern the coupling of the pharyngeal phase to the esophageal phase of swallowing.

The Effect of an Effortful Swallow on the Normal Adult Esophagus

The effect of an effortful swallow on the healthy adult esophagus was investigated using concurrent oral and esophageal manometry (water perfusion system) on ten normal adults (5 males and 5 females, 20-35 years old) while swallowing 5-ml boluses of water. The effects of gender, swallow condition (effortful versus noneffortful swallows), and sensor site within the oral cavity, esophageal body, and lower esophageal sphincter (LES) were examined relative to amplitude, duration, and velocity of esophageal body contractions, LES residual pressure, and LES relaxation duration. The results of this study provide novel evidence that an effortful oropharyngeal swallow has an effect on the esophageal phase of swallowing. Specifically, effortful swallowing resulted in significantly increased peristaltic amplitudes within the distal smooth muscle region of the esophagus, without affecting the more proximal regions containing striated muscle fibers. The findings pertaining to the LES are inconclusive and require further exploration using methods that permit more reliable measurements of LES function. The results of this study hold tremendous clinical potential for esophageal disorders that result in abnormally low peristaltic pressures in the distal esophageal body, such as achalasia, scleroderma, and ineffective esophageal motility. However, additional studies are necessary to both replicate and extend the present findings, preferably using a solid-state manometric system in conjunction with bolus flow testing on both normal and disordered populations, to fully characterize the effects of an effortful swallow on the esophagus.

Videofluoroscopic evaluation of HIV/AIDS patients with swallowing dysfunction.

We investigated the association of abnormalities of the swallowing mechanism in the oral and pharyngeal phases of swallowing with symptoms of dysphagia and painful swallowing in patients with human immunodeficiency virus (HIV). Seventeen patients, two with HIV and 15 with acquired immunodeficiency syndrome (AIDS), with symptoms of dysphagia or pain on swallowing for routine barium esophagograms were studied prospectively by videofluoroscopic examination of the oropharynx in addition to a routine biphasic esophagogram. The videofluoroscopic studies were performed in conjunction with a speech pathologist. All 17 patients demonstrated abnormalities in the oral, pharyngeal, or esophageal phase of swallowing. Eight patients aspirated, six of whom did not exhibit a cough reflex and were classified as silent aspirators. Seven of the eight patients who aspirated had chest radiographs consistent with aspiration pneumonia. A significant number of HIV-positive and AIDS patients with dysphagia or pain on swallowing have dysfunction of the swallowing mechanism and are at risk for aspiration.

Effects of atropine on the central mechanism of deglutition in anesthetized sheep.

The role of acetylcholine in the central mechanism of swallowing remains a matter of debate. The aim of this work, conducted in sheep, was to assess the effects of anti-muscarinic drugs (mainly atropine) on the activity of peripheral muscles involved in the oropharyngeal and esophageal phases of swallowing, and on that of dorsal medulla interneurons which program swallow-induced esophageal contractions and therefore belong to the so-called central pattern generator. Our results were obtained in anesthetized animals by means of electromyographic and manometric recordings of peripheral muscle contractions associated with microelectrode recordings of medullary interneuron discharge. They show that both interneuron discharge and primary esophageal contractions that follow the oropharyngeal component of swallowing were suppressed under atropine (0.1--0.5 mg/kg). In contrast, atropine did not impede the swallowing oropharyngeal component, the secondary peristalsis and the "deglutitive inhibition," which affects the esophageal motility during the oropharyngeal phase of swallowing. In conclusion, muscarinic receptors (probably not those of M(1)type) appear to control the primary peristalsis, but neither the secondary peristalsis nor the deglutitive inhibition.

Central integration of swallow and airway- protective reflexes

The relationship between the timing of respiration and swallowing has been proven not to be random. Using pseudorabies virus (PRV) as a transsynaptic neural tracer, a basis for the central integration of swallowing and airway-protective reflexes can be located in the neural circuits projecting to swallowing-related muscles. The premotor neurons (PMNs) that constitute the swallowing central pattern generators, interneuronal networks able to initiate repetitive rhythmic muscle activity independent of sensory feedback, connect with multiple areas of the brainstem and other areas of the central nervous system. Those PMNs that project to muscles used in swallowing have been localized within the nucleus of the solitary tract (NTS) and its adjacent reticular formation, and they are synaptically linked both to peripheral afferents and to cortical swallowing areas. Bartha PRV, an attenuated vaccine strain of swine α-herpesvirus with a long postinjection survival rate and the ability to produce controlled infections that spread in a hierarchical manner within synaptically linked neurons, can specifically label neurons projecting to PMNs of a given circuit. Thus, it has been used to isolate two neuroanatomically distinct subnetworks of PMNs involved in the buccopharyngeal and esophageal phases of swallowing. Use of PRV as a neural tracer shows that during the buccopharyngeal phase of swallowing, vagal afferents from the pharynx and larynx and from the superior laryngeal nerve terminate in the intermediate and interstitial subnuclei of the NTS. Motoneurons projecting to the pharynx and larynx are located in the semicompact and loose formations of the nucleus ambiguus (NA). Neural tracing with PRV also shows that esophageal PMNs have direct synaptic contact with esophageal motoneurons in the compact formation of the NA. Moreover, esophageal PMNs are localized exclusively to the central subnucleus of the NTS, a site that also is the sole point of termination of esophageal vagal afferents. Using PRV, one can identify third-order (neurons projecting to PMNs) esophageal neurons in sites where pharyngeal PMNs have been noted. Injection of PRV into the esophagus and subsequent detection using immunofluorescence found a subpopulation of neurons in the intermediate and interstitial subnuclei of the NTS. This subpopulation projects to pharyngeal motoneurons and buccopharyngeal PMNs, and it is synaptically linked to esophageal PMNs. The synaptic link between buccopharyngeal and esophageal PMNs provides a potential anatomic substrate within the NTS for the central integration of esophageal peristalsis with the pharyngeal phase of swallowing and airway-protective reflexes. Human studies and animal models investigating esophagoglottal closure and pharyngo–upper esophageal sphincter (pharyngo-UES) contractile reflexes have located the neural pathways that mediate airway-protective reflexes. Similar studies and models using two PRV strains injected simultaneously into different swallowing and respiration-related muscle groups may identify synaptic connectivity between laryngeal, esophageal, and pharyngeal PMNs and, thus, may help to demonstrate the central integration of swallowing and airway-protective reflexes.

The Assessment of Oral, Pharyngeal and Esophageal Dysphagia in Elderly Persons

The prevalence of swallowing disorders in elderly persons is increasing rapidly. Many technological and bedside assessments are used to assess difficulties in the oral, pharyngeal and esophageal phases of swallowing. Each of these evaluation methods has specific uses, limitations and drawbacks. The therapist involved in the assessment of swallowing must be aware of the availability of these assessment tools and their special applications to the elderly population. This literature review covers the methodologies commonly in use in the clinical setting, with particular emphasis on the special considerations necessary when assessing dysphagia in elderly individuals.

The search for the central swallowing pathway: the quest for clarity.

As the work of Dr. Martin Donner has brought a clarity to understanding swallowing, so has the work of various neuroscientists, including that of a Nobel Laureate, in providing us with a better comprehension of this complex motor pattern. Understanding the neural control of swallowing has been a process that has occurred during this century in which several investigators, primarily from Europe, Japan, Canada, and the United States, have brought their perspectives in applying particular techniques to decipher how the central and peripheral nervous system control swallowing. Swallowing represents a complex muscular response of the oral, pharyngeal, and esophageal regions which are integrated to provide an effective functional pattern that prepares and transports food while simultaneously protecting the airway. This adaptation of the upper gastrointestinal tract in mammals has been extensively studied peripherally by two methods: recording from the peripheral nerves and muscles, and stimulating peripheral nerves and their receptive fields that can induce the pharyngeal and esophageal phases of swallowing. The study of the peripheral nervous system has provided insight into the sensory receptive fields that evoke or facilitate swallowing, and has established the first serious evidence of the all-or-none sequential contraction pattern of the oropharyngeal and esophageal muscles. It has been these electromyographic studies of the muscles that has established much of the criteria for evaluating the central swallowing pathway. Five techniques have been applied to the central nervous system to study swallowing and include lesioning or destroying discrete regions to determine how swallowing is impaired or modified, electrically stimulating the central neural tissue to determine the type of effects on swallowing, recording from the central neural tissue with macro- and microelectrodes to ascertain when neurons respond in timing to the peripheral muscle activity during swallowing, applying pharmacological agents through micropipettes which could mimic or inhibit potential transmitters, and using immunochemical techniques to tag specific chemicals that could be transmitters used by the neurons in the central swallowing pathway. These various techniques have provided insight into how the central swallowing pathway is organized but the details of the central control are still in the process of being defined and will require as much effort this next century as has been previously developed over the past 90 years.

Approaches to the patient with aspiration and swallowing disabilities

Aspiration, or soiling of the tracheobronchial tree, can produce life-threatening pulmonary disease. Intermittent or persistent aspiration may cause symptoms including cough, intermittent fever, recurrent tracheobronchitis, atelectasis, pneumonia, and/or empyema. The pulmonary disease may be associated with weight loss, cachexia, and dehydration. In many cases the aspiration is caused by laryngeal dysfunction, allowing pulmonary contamination by swallowed material. In other cases the aspiration is caused by a dysfunction of the oral, pharyngeal, or esophageal phases of swallowing. In some cases the aspiration is caused by a combination of laryngeal and swallowing dysfunction. Geriatric patients are more likely to experience aspiration, since muscle weakness causing mechanical disability and neurologic impairment are more common in this age group. Therefore, with the ever-increasing aging of our population, these disabilities will be on the rise, with an associated increase in pulmonary disease and death. The approach to evaluation and management of these disorders must be based on an understanding of the underlying functional impairment.

Oropharyngeal dysphagias in the dog: A cinefluorographic analysis of experimentally induced and spontaneously occurring swallowing disorders

Cinefluorography and videofluorography were used to record and analyze functional swallowing deficits of 12 dogs with spontaneously occurring oropharyngeal dysphagias and six experimental dogs with selected neurectomies. Ten of the 12 dogs had dysphagias affecting the cricopharyngeal stage of the oropharyngeal phase of swallowing. Two dogs had mixed oropharyngeal dysphagias. Clinical signs of cricopharyngeal dysphagia could not be differentiated from those of dysphagias due to pharyngeal or mixed oropharyngeal deficits. Signs of cricopharyngeal dysphagia consisted of: 1) repeated attempts to swallow; 2) excessive head movement; 3) dropping food from the mouth after unsuccessful swallowing attempts; 4) reingestion of dropped food. Nine of these dogs had cinefluorographic evidence of asynchrony between the normal pharyngeal contraction and relaxation, and subsequent cricopharyngeal relaxation and contraction. Only one dog demonstrated a consistent cricopharyngeal non‐opening (achalasia). Seven of the dogs responded dramatically to cricopharyngeal myotomy. Two dogs with mixed oropharyngeal dysphagias had poor contractility of the pharyngeal muscles in addition to cricopharyngeal dysphagia. Clinical and cinefluorographic evaluation following cricopharyngeal myotomy of one dog verified exacerbation of functional deficits due to the iatrogenic cricopharyngeal chalasia. Esophagopharyngeal reflux accentuated the contrast medium retention in the pharynx and laryngotracheal aspiration. The need was stressed for careful differentiation between cricopharyngeal dysphagia and dysphagias involving the pharyngeal stage. Four experimental dogs with selective bilateral neurectomies of branches of the glossopharyngeal (IX) and vagus (X) nerves were evaluated clinically and cinefluorographically in an attempt to identify the pathogenesis of cricopharyngeal dysphagia. The variable results in the four dogs and the observed recovery in two dogs suggested that peripheral motor nerve deficits are not a major cause of cricopharyngeal dysphagia. Glossopharyngeal neurectomy in two dogs induced a profound functional disorder involving the pharyngeal and cricopharyngeal stages and the esophageal phase of swallowing. This would support a new hypothesis that the glossopharyngeal nerve is sensory to the esophagus as well as the pharynx, and may play a major role in disorders of the pharynx, upper esophageal sphincter, and esophagus, including congenital or acquired megaesophagus.