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PubMed2002

Kinematic strategies for hyoid movement in rapid sequential swallowing.

Past videofluoroscopic and EMG evidence has shown that rapid sequential swallowing differs from discrete swallows, but our knowledge of the control strategies remains incomplete. This study examined in detail the interrelationships among kinematic variables to discern the strategies for deglutitive hyoid motion during discrete (5 cc, 10 cc, 20 cc, 30 cc) and rapid sequential (120 cc) swallowing tasks. Submental ultrasound was conducted with head and transducer stabilization on 30 healthy subjects (15 males, 15 females) in three age groups (20-39, 40-59, 60-79 yrs). Frame-by-frame changes in hyoid position were tracked from digitized images of 236 discrete and 318 rapid sequential swallows. Repeated-measures analyses of variance were conducted on a number of kinematic variables with corrections for multiple tests and comparisons. The main effect of task was significant for all variables except forward peak velocity. Per post hoc contrasts, rapid sequential swallows had significantly reduced maximal amplitude (maximal displacement), total distance, backward peak velocity, at-max and total durations, and time to backward peak velocity in comparison with discrete swallows of any volume. Amplitude "down-scaling" was the prominent kinematic strategy used to accomplish rapid sequential swallows in a shorter time while keeping forward peak velocity essentially unchanged. In contrast, amplitude "up-scaling" was the strategy for accommodating larger-volume discrete swallows. Our results confirm built-in flexibility in the functional range of deglutitive hyoid motion.

Adult↗
PubMed1998

Age and volume effects on liquid swallowing function in normal women.

Understanding the nature of swallowing in persons without swallowing problems is a prerequisite to evaluating the nature and extent of dysphagia in persons with compromised swallowing. In order to determine how swallowing varies with age and with liquid bolus volume in women, we assessed 167 normal female swallowers videofluoroscopically and obtained multiple measures of swallowing function. The women in this study demonstrated a change in swallowing function with age, due primarily to an increase in pharyngeal transit and total duration of the motor response. The duration of closure and opening of valves in the upper aerodigestive tract also increased with age, and the duration of laryngeal elevation and hyoid movement peaked in the 60-79-year-old age groups. Bolus volume effects were quite consistent across most measures. As the bolus volume increased from 1 ml to 10 ml, transit times decreased and durations of valve closure and opening increased. The results of this study may be used to specify the relationship of swallowing function to age and liquid bolus volume in women, relationships that heretofore have been observed only in part and in smaller and more heterogeneous populations.

Adult↗
PubMed1997

Superior laryngeal nerve stimulation in the cat: effect on oropharyngeal swallowing, oesophageal motility and lower oesophageal sphincter activity.

Superior laryngeal nerve (SLN) stimulation can activate the brainstem swallowing mechanism to produce a complete swallowing sequence consisting of oropharyngeal, oesophageal and lower oesophageal sphincter (LOS) components. However, little is known of the effect of SLN stimulation (peripheral-sensory input from the pharynx) on the characteristics of oesophageal motor activity, especially in the smooth muscle portion. The present study examined the effect of varying stimulus train length and frequency on each of the three components of the reflex. Acute studies were performed in urethane anaesthetized cats. Oesophageal motility was monitored using conventional manometric techniques, and oropharyngeal swallowing by the mylohyoid electromyogram. SLN stimulus train length (1-10 sec) and frequency (5-30 Hz) were varied independently. Increased train length or frequency resulted in (1) an increase in oropharyngeal swallowing and incidence of the complete swallowing response, (2) an increase in latency to onset of the oesophageal peristaltic wave, (3) reduction of the amplitude of the evoked peristaltic contraction in the smooth muscle portion, without altering its velocity, (4) increased LOS relaxation, and increased LOS after-contraction. The LOS contraction was abolished by atropine (100 micrograms kg-1). Therefore, increased SLN stimulation not only results in excitation of the central swallowing program and the oropharyngeal stage of swallowing, but has major effects on the oesophageal and LOS stages of swallowing. Afferent SLN stimuli can impact on the control mechanisms for each stage, to inhibit or excite the stages in different ways.

Animals↗
PubMed2001

Induction of cortical swallowing activity by transcranial magnetic stimulation in the anaesthetized cat.

Transcranial magnetic stimulation (TMS) over human fronto-central areas of scalp can activate short latency responses in the muscles of the face, pharynx and oesophagus. However, the physiological relationship between this early activity and the swallowing activity programmed by the brainstem central pattern generator (CPG) remains unclear. The aim of this study was to explore the relationship between TMS-induced early muscle and late swallowing activities in the feline model. Twelve adult cats were studied under light anaesthesia. Mylohyoid and oesophageal EMG, together with pharyngeal, upper oesophageal sphincter (UOS) and upper oesophageal manometry, were recorded to single-pulse TMS of cat cortex. TMS at low stimulation intensities evoked consistent short latency EMG responses in the mylohyoid and oesophageal muscles (6.1 +/- 1.2 ms and 12.7 +/- 0.7 ms, respectively), and early contractile activity in the UOS (latency 31.8 +/- 3.6 ms). By contrast, TMS at high intensities induced swallowing activity as indicated by mylohyoid EMG, and UOS relaxation (latencies 1.1 +/- 0.4 s and 0.8 +/- 0.1 s, respectively). Both the early muscle and late swallowing activities were intensity-dependent, increasing stimulus strength producing a reduction in latency and greater number of swallows. The characteristics of the early response suggest an oligosynaptic projection from cortex to swallowing muscles. The induction of swallows at high intensities suggests a requisite for greater recruitment of cortical motoneurones, or associated swallowing regions.

Animals↗
PubMed2000

Central nervous system nitric oxide induces oropharyngeal swallowing and esophageal peristalsis in the cat.

BACKGROUND & AIMS: The functional role of brainstem nitric oxide (NO) in swallowing and esophageal peristalsis remains unknown. We examined the effects of blockade of central nervous system (CNS) NO synthase (NOS) on swallowing and on primary and secondary peristalsis. METHODS: (1) The effect of intravenous (IV) NOS inhibitor N(G)-nitro-L-arginine (L-NNA) on swallowing and swallowing-induced peristalsis was examined. (2) An NOS inhibitor (N(G)-monomethyl-L-arginine [L-NMMA]) was administered into the fourth ventricle intracerebroventricularly (ICV), and its effects on swallowing and primary and secondary peristalsis were examined. RESULTS: (1) IV L-NNA significantly reduced the number of oropharyngeal swallows and the induction of primary peristalsis in the smooth muscle portion of the esophageal body; the change was not significant within the striated muscle portion. (2) L-NMMA given ICV significantly reduced the number of oropharyngeal swallows and the incidence of primary peristalsis in both smooth and striated muscle, but the reduction in amplitude was significant only for the smooth muscle contraction. There was a significant reduction in both the amplitude and incidence of secondary peristalsis, only in the smooth muscle portion. CONCLUSIONS: CNS NO is an important neurotransmitter in the induction of oropharyngeal swallowing and esophageal peristalsis. The neural substrates mediating striated and smooth muscle peristalsis may be both anatomically and neurochemically distinct.

Animals↗
PubMed2000

Management of swallowing disorders in head and neck cancer patients: optimal patterns of care.

This article presents optimal patterns of care for management of head and neck cancer patients. Discussion includes how the head and neck cancer multidisciplinary team makes decisions regarding treatment for head and neck cancer patients and the role of the speech pathologist as part of the team. Specifically addressed issues are how speech pathologists can become team members, provide pretreatment intervention, and implement clinical and instrumental assessment of swallowing and swallowing treatment. Types of treatments for head and neck cancer are described, including surgical and organ preservation (radiotherapy with or without chemotherapy). Types of surgeries are described, including surgical resection and surgical reconstruction with discussion of the effects of both resection and reconstruction on swallowing. Management of swallowing disorders in the partial laryngectomy, total laryngectomy, partial pharyngectomy, and oral cancer patient are reviewed, as well as use of palatal prostheses and the speech pathologist's role in collaborative construction of the prosthesis and follow-up management of swallowing. Types of radiotherapy and chemotherapy treatments and their side effects are discussed as are specific types of swallowing problems seen after these therapies and management of swallowing in this population. Optimal care patterns, including timing and duration of swallow management specific to various head and neck cancer populations, are presented.

Child, Preschool↗
PubMed2000

The role of swallowing during active sleep in the clearance of reflux in term and preterm infants.

OBJECTIVES: To investigate swallowing and peristalsis in sleep and during gastroesophageal reflux (GER) in both healthy term and preterm infants at term equivalent age. STUDY DESIGN: Multichannel recordings were made in 12 healthy term and 11 preterm infants, under the same conditions, after feeding. Sleep state, cardiorespiratory variables, esophageal pH, and pharyngeal swallowing and peristalsis were measured. GER was defined as pH <4 for > or = 15 seconds, and swallows were classified as pharyngeal only, primary peristalsis (propagated, dropped, interrupted), or secondary peristalsis. RESULTS: Spontaneous swallowing rate was not significantly different between term and preterm infants and was sleep state-related, occurring in active sleep but rarely in quiet sleep. In response to acid GER, term infants significantly increased pharyngeal swallowing from a median of 0.7 (25th-75th interquartile range, 0.5-0.9) to 1.7 (1.0-3.0) swallows/min and secondary peristalsis from a median of 0.5 (25th-75th interquartile range, 0.3-0.8) to 1.1 (0.8-2.0) waves/min (P <.05). In contrast, the preterm infants demonstrated a significantly higher proportion of fully propagated peristaltic swallows compared with the term infants (53% and 27%, respectively) (P <.05). CONCLUSION: The occurrence of swallowing is sleep state-related. In active sleep, term infants clear GER by increasing swallowing and secondary peristalsis, whereas preterm infants at term equivalent age clear GER by increasing propagated peristalsis. This method of clearance would explain the mechanism by which preterm infants have significantly shorter episodes of reflux than term infants.

Deglutition↗
PubMed2005

Comparison of disordered swallowing patterns in patients with recurrent cortical/subcortical stroke and first-time brainstem stroke.

OBJECTIVE: To describe the disordered swallowing patterns in recurrent cortical/subcortical stroke and first-time brainstem stroke. DESIGN: A retrospective study. SUBJECTS: Forty-seven consecutive patients, 28 with recurrent cortical/subcortical stroke and 19 with first-time brainstem stroke, referred for dysphagic evaluation to the rehabilitation department of a medical centre. METHODS: Thirty-five male and 12 female patients with a mean age of 62.0+/-11.5 years were included. The median post-stroke duration was 17.0 days. The records of clinical examination and a videofluoroscopic study of swallowing were collected through chart review. The percentages of abnormalities seen at clinical examination and videofluoroscopic swallowing study between recurrent cortical/subcortical stroke and first-time brainstem stroke patients were compared using a chi-square test. RESULTS: The recurrent cortical/subcortical patients suffered from a higher rate of impaired tongue movement, drooling and aphasia at clinical examination and a higher percentage of swallowing abnormalities in oral-preparatory and oral phases in the videofluoroscopic swallowing study. The abnormal videofluoroscopic findings in first-time brainstem stroke patients predominantly occurred in the pharyngeal phase. Both groups had more difficulties swallowing thin barium than they did swallowing the thick and paste barium. CONCLUSION: The recurrent cortical/subcortical stroke and first-time brainstem stroke patients show different manifestations in some parameters of both clinical examination and videofluoroscopic swallowing study.

Aged↗
PubMed2005

Prognostic implications of swallowing ability in elderly patients after initial recovery from stroke.

BACKGROUND: It remains unclear how swallowing assessment can help clinicians to predict the risk for pneumonia in elderly persons after ischemic stroke. A prospective case-control study was conducted to evaluate the prognostic utility of swallowing ability assessments. METHODS: Participants were 136 elderly persons who had an acute ischemic stroke 3-12 months previously. They were separated into four groups based on their history of repeated episodes of pneumonia in combination with swallowing ability: Group 1 had neither repeated pneumonia nor swallowing abnormality (n = 69); group 2 had repeated pneumonia but no swallowing abnormality (n = 0); group 3 had swallowing abnormality but no repeated pneumonia (n = 54); and group 4 had both swallowing abnormality and repeated pneumonia (n = 13). The follow-up period was as long as 2.2 years. Outcomes and causes of death were compared among the groups. RESULTS: During the study, the overall mortality rate was higher in group 3 (24 deaths, 44.4%) and group 4 (9 deaths, 69.2%) than in group 1 (3 deaths, 4.3%, both p <.05). The annual mortality rate from pneumonia was also significantly higher in group 3 (21.2%) and group 4 (38.2%) than in group 1 (0.8%, p <.0001). The odds ratio for patients who subsequently died of pneumonia was 46.8 between groups 1 and 3. CONCLUSIONS: The high sensitivity (.96) and specificity (.68) of swallowing ability indicate that the method is useful for identifying those persons at greatest risk for pneumonia and death after ischemic stroke.

Aged↗
PubMed1997

Fetal swallowing: relation to amniotic fluid regulation.

In summary, fetal swallowing activity contributes importantly to fetal and amniotic fluid homeostasis, and fetal somatic and gastrointestinal development. Human and ovine fetal swallowing increases throughout gestational with fetal swallowed volumes markedly greater (relative to body weight) than adults. Although the regulation of swallowing activity in early gestation is unknown, intact central and systemic dipsogenic mechanisms have been shown during the last third of ovine gestation. Recent studies suggest that swallowing behavior may be modulated in accordance with neurobehavioral state changes and influenced by hypoxia, hypotension and plasma osmolality changes. Whether fetal swallowing also is regulated by the development of "hunger" sensation, salt appetite, or the development of taste is uncertain. Nevertheless, it is likely that, for species in which swallowing behavior develops in utero, there are potentially dramatic influences of the maternal-fetal pregnancy environment on the imprinting of regulatory mechanisms controlling ingestive behavior. Ultimately, the regulation of fetal swallowing may aid in the prevention and/or therapy of human amniotic fluid disorders.

Adult↗
PubMed1998

Hot water swallows improve symptoms and accelerate esophageal clearance in esophageal motility disorders.

Cold liquid ingestion may precipitate episodes of dysphagia and chest pain in patients with spastic esophageal motility disorders. The effect of hot liquids on esophageal symptoms, esophageal peristalsis, and clearance and any potential therapeutic benefit in such patients has not been examined. Using esophageal scintigraphy and manometry, we have investigated the effects of hot water swallows on dysphagia, chest pain, and esophageal motility and clearance in patients with esophageal motility disorders. We studied 48 men and women with intermittent dysphagia to both solids and liquids, chest pain, and/or regurgitation. All patients underwent upper endoscopy, barium swallow, and esophageal manometry using standard techniques. Esophageal scintigraphy assessed esophageal transit time (ETT) and retrograde intraesophageal movement of bolus at baseline (22 degrees C) and after hot (60 degrees C) water swallows. Esophageal manometry assessed the amplitude and duration of esophageal contractions in response to baseline and hot water swallows. Patients were followed clinically for as long as 6 months to assess symptomatic response. We found that baseline esophageal scintigraphy revealed a mean ETT of 48.5 seconds; after hot water swallow, mean ETT was 27.8 seconds (p < 0.001). The number of secondary peaks at baseline was 3.5; after hot water swallow, it was 2.1 (p < 0.001). Baseline esophageal manometry showed a mean esophageal body contraction amplitude of 188 mm Hg (mean duration, 11.8 seconds) in response to wet swallows and 125 mm Hg (mean duration, 5.7 seconds) with hot water swallows (p < 0.001). Clinically, 28 (58%) of 48 patients noted significant (>50%) improvement of their symptoms and have been ingesting hot water or other hot liquids regularly with their meals. We conclude that hot water accelerates esophageal clearance, decreases the amplitude and duration of esophageal body contractions, and improves symptoms in patients with esophageal motility disorders. Because of its safety and simplicity, it may have an important role in the management of these chronic conditions.

Deglutition↗
PubMed2006

Direct measurement of subglottic air pressure while swallowing.

OBJECTIVE: The subglottic pressure theory for swallowing asserts that laryngeal mechanoreceptors have a role in the regulation of swallowing function. The primary purpose of this study was to determine if subglottic air pressure is generated during swallowing in a healthy, nontracheostomized person. METHODS: This pilot investigation used a prospective, repeated-measures design in a single subject. Direct measurement of subglottic air pressure was obtained through percutaneous puncture of the cricothyroid membrane. Swallows were timed with four randomly assigned lung volumes: total lung capacity, tidal volume, functional residual capacity (FRC), and residual volume. RESULTS: Lung volumes above FRC generated positive subglottic pressure during the swallow, whereas lung volumes below FRC generated consistently negative subglottic pressures. The degree and polarity of the pressure was directly related to lung volume at the time of the swallow. CONCLUSION: These findings illustrate that during normal swallowing, positive subglottic air pressure is likely present. Previously, subglottic air pressure during swallowing had been measured in tracheostomy patients only.

Adult↗
PubMed2006

Improved infant swallowing after gastroesophageal reflux disease treatment: a function of improved laryngeal sensation?

OBJECTIVE: The objective of this study was to describe improvements in pediatric swallowing after gastroesophageal reflux treatment. STUDY DESIGN: The authors conducted a retrospective database and chart review at two tertiary care children's hospitals. PARTICIPANTS: Patients (21 males, 7 females) ranged in age from 1 to 32 months. All patients had clinical evidence of gastroesophageal reflux disease (GERD) as well as evidence of dysphagia with aspiration (laryngeal vestibule and/or trachea) or hypopharyngeal pooling on flexible endoscopic evaluation of swallowing and sensation testing (FEESST) or videofluoroscopic swallow study (VSS). INTERVENTION: Each child underwent either medical or surgical intervention for control of their GERD. OUTCOME MEASURES: Outcome measures were change in laryngopharyngeal sensation and swallowing function with repeat swallow evaluation after GERD treatment. RESULTS: A significant improvement in both swallow function and sensory testing was demonstrated after GERD treatment. CONCLUSIONS: GERD may result in decreased laryngopharyngeal sensitivity, which may contribute to pediatric swallowing dysfunction. Control of GERD may improve swallow function. These findings have important clinical implications that need further study.

Child, Preschool↗
PubMed2007

Early swallowing problems in a cohort of patients with nasopharyngeal carcinoma: Symptomatology and videofluoroscopic findings.

OBJECTIVE: To study the incidence and the degree of swallowing dysfunction in patients with nasopharyngeal carcinoma (NPC) who underwent radiation therapy treatment. INSTITUTION: The study was conducted in the Prince of Wales Hospital, a tertiary teaching hospital of the Chinese University of Hong Kong. MATERIALS AND METHODS: From October 1999 to July 2001, a cohort of 20 consecutive patients with newly diagnosed NPC was prospectively studied. Questions about symptoms, including swallowing functions, were asked, and head and neck examination including oromotor examination was performed in the subjects before radiation therapy. All patients were subjected to videofluoroscopy (VFSS) to assess their swallowing function. Abnormalities were scored if they were present on two of three swallow attempts. The patients were reassessed at 6 months and 12 months after radiotherapy by symptom assessment and VFSS. RESULTS: There were 14 male and 6 female patients. The mean age was 43.9 years. Nine patients had early (stage I and II) disease, whereas 11 patients had advanced (stage III and IV) disease. Nine patients were treated by radiation therapy only and 11 patients by concurrent chemoirradiation. Ninety-five percent of the subjects had subjective dysphagia at 6 and 12 months after radiation therapy. Ninety percent had xerostomia, and 80% had to avoid certain foods at 12 months postradiation therapy. All subjects had to alternate solid food with fluid intake to facilitate swallowing. An average reduction of jaw movement by 1 cm was noted. A large proportion of patients had stasis of food in the pharynx (100% in valleculae and 60% in pyriform fossae) and impaired pharyngeal peristalsis (60%). One quarter of patients had laryngeal penetration. CONCLUSIONS: Subjective swallowing difficulties were common in patients in the early follow-up period after radiation therapy for NPC according to questionnaire assessment. An objective swallowing study revealed that swallowing dysfunction was persistent 12 months after radiation therapy.

Adult↗
PubMed1997

An optimization model for mastication and swallowing in mammals.

Mammalian mastication is a process combining simultaneous food comminution and lubrication. The initiation of swallowing, which is voluntary, has been thought to depend on separate thresholds for food particle size and for particle lubrication. Instead of this duality, we suggest that swallowing is initiated when it is sensed that a batch of food particles is binding together under viscous forces so as to form a bolus. Bolus formation ensures that when the food mass is swallowed, it will pass the pharyngeal region safely without risk of inhaling small particles into the lower respiratory tract. Crucial for bolus formation is food particle size reduction by mastication. This allows the tongue to pack particles together tightly by pressure against the hard palate. A major function of salivation is to fill the gradually reducing spaces between particles, so increasing viscous cohesion and promoting bolus formation. If swallowing is delayed, excessive saliva floods the bolus, separating particles and reducing cohesion. Swallowing then becomes more precarious. Our model suggests that there is an optimum moment for a mammal to swallow, defined in terms of a peak cohesive force between food particles. The model is tested on human mastication with two foods, brazil nut and raw carrot, which have very different particle size breakdown rates. The peak cohesive force is much greater with brazil nuts but both foods are predicted to be swallowed after similar numbers of chews despite the very different food particle size reductions achieved at that stage. The predicted number of chews to swallow is in broad agreement with published data.

Animals↗
PubMed1996

Measurement of swallowing in patients with sore throats.

Swallowing function was measured using a simple timed test in 20 healthy subjects with a sore throat (16 women, median age [range] 27.5 years [19.3-44.5]) and the test was repeated following recovery. All three indices from the test average volume per swallow (ml), average time per swallow (s) and swallowing capacity (mls-1) were significantly improved following recovery (P = 0.0001, 0.041 and 0.0001 respectively). There was no significant change in respiratory function between the two visits. The indices from a timed test of swallowing are sensitive enough to detect changes occurring due to a sore throat; the test provides a simple bedside technique for quantifying swallowing and may be useful in measuring the rate of recovery from swallowing problems and in assessing the effect of different treatments on swallowing function.

Adult↗
PubMed2003

Role of mastication and swallowing in the control of autonomic nervous activity for heart rate in different postures.

Mastication and swallowing increase the heart rate, and posture change and respiration also modulate the heart rate. To clarify the role of mastication and swallowing in the modulation of the autonomic nervous activity, we investigated how they interact with modulation of the heart rate by changing body positions and respiration in young healthy subjects. R-R intervals of electrocardiogram at rest were significantly changed with different body positions, compared with supine and standing. A net shortening by mastication of a chewing gum base was similar in various postures. Respiration induced a periodic change in the R-R intervals, depending on the body postures, but mastication did not markedly change them in each posture. Dry swallowing at rest and spontaneous swallowing during the mastication in the sitting position induced a similar transient shortening and suppressed the respiration-induced changes after the swallowing. The net transient shortening by dry swallowing at rest was similar in the different postures. These results suggest that signals from mastication and swallowing are summated with those from body positions and respiration for shortening the R-R intervals and that signals from swallowing suppress the respiration-induced periodic changes.

Adult↗
PubMed2004

Changes in masseter muscle activity associated with swallowing.

The purpose of this study was to investigate masseter muscle activity during swallowing in seven healthy humans. In order to observe both the increase and the decrease of masseter muscle activity, the subjects performed voluntary saliva swallowing while low-intensity tonic clenching was maintained. Electromyograms (EMG) were recorded from the right masseter muscle and the suprahyoid muscle complex. For six of seven subjects, the masseter EMG amplitude increased above the pre-swallow baseline level at the initial phase of swallowing. This increase was initiated 0.1 +/- 0.3 s before the suprahyoid EMG onset and was terminated 0.6 +/- 0.4 s after the suprahyoid EMG onset. For six of seven subjects, the masseter EMG amplitude decreased below the pre-swallow baseline level during swallowing. This decrease was initiated 0.6 +/- 0.3 s after the suprahyoid EMG onset and was terminated 1.3 +/- 0.4 s after the suprahyoid EMG onset. These findings indicate that biphasic modulation of masseter motoneuron excitability occurs during swallowing in humans. Further investigations are needed to determine whether these findings are extensively applicable to swallowing as it occurs under natural conditions.

Adult↗