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Purpose: Within-individual pharyngeal swallowing pressure variability differs among pharyngeal regions in healthy individuals and increases with age. It remains unknown if pharyngeal pressure variability is impacted by volitional swallowing tasks. We hypothesized that pressure variability would increase during volitional swallowing maneuvers and differ among pharyngeal regions depending on the type of swallowing task being performed. Method: Pharyngeal high-resolution manometry was used to record swallowing pressure data from 156 healthy participants during liquid (5 cc) or saliva swallows, and during volitional swallowing tasks including effortful swallow, Mendelsohn maneuver, Masako maneuver, or during postural adjustments. The coefficient of variation was used to determine pressure variability of velopharynx, tongue base, hypopharynx, and upper esophageal sphincter regions. Repeatedmeasures analysis of variance was used on log-transformed data to examine effects of pharyngeal region and swallowing tasks on swallow-to-swallow variability. Results: There was a significant main effect of task with greater pressure variability for the effortful swallow (p = .002), Mendelsohn maneuver (p < .001), Masako maneuver (p = .002), and the head turn (p = .006) compared with normal effort swallowing. There was also a significant main effect of region (p < .01). In general, swallowing pressure variability was lower for the tongue base and upper esophageal sphincter regions than the hypopharynx. There was no significant interaction of task and region (effortful, p = .182; Mendelsohn, p = .365; Masako, p = .885; chin tuck, p = .840; head turn, p = .059; and inverted, p = .773). Conclusions: Pharyngeal swallowing pressure variability increases in healthy individuals during volitional swallowing tasks. Less stable swallow patterns may result when tasks are less automatic and greater in complexity. These findings may have relevance to swallowing motor control integrity in healthy aging and individuals with neurogenic dysphagia., Safe and effective swallowing is a life-sustaining and complex action that requires proper coordination of more than 25 pairs of muscles with signaling over six cranial nerves and four cervical [...]

Purpose: Dysphagia is thought to be prevalent and a leading cause of morbidity and mortality in people with Parkinson disease (PwPD). The aim of this study was to compare the frequencies of atypical and extreme values for measures of swallowing physiology in PwPD and in an age- and sex-matched cohort of healthy adults. Atypical and extreme values were defined, respectively, as values falling in the 25% and 5% tails of the reference distribution for healthy adults under age 60 years. Method: A standard videofluoroscopy (VF) protocol was performed in 17 adults with mild PD and 17 age- and sex-matched healthy adults using 20% w/v liquid barium ranging from thin to extremely thick consistency. Blinded VF analysis was performed according to the Analysis of Swallowing Physiology: Events, Kinematics and Timing Method. Frequencies for atypical and extreme values were tabulated by cohort and compared using odds ratios. Results: Increased frequencies of atypical values (> 25%) were seen in the PwPD for prolonged swallow reaction time, prolonged time-to-laryngeal-vestibule-closure (LVC), and poor pharyngeal constriction. However, these findings were also observed in the healthy controls. The PwPD showed significantly higher odds of atypical values for narrow upper esophageal sphincter (UES) diameter on thin liquids, a short hyoid-burst-to-UES-opening interval on extremely thick liquids, and prolonged time-to-LVC, LVC duration, and UES opening duration on multiple consistencies. The frequencies of extreme values failed to show any significant cohort differences for any parameter. Conclusions: In this study, a group of people with mild PD did not show clear evidence of swallowing impairments distinct from the changes seen in a healthy age-matched control group when odds ratios were used to compare the frequencies of atypical values between PwPD and the control group; only a few parameters showed significant differences. These were findings of significantly higher frequencies in PwPD of prolonged LVC and UES opening duration. Supplemental Material: https://doi.org/10.23641/asha. 15032241, Parkinson disease (PD) is one of the most common neurological disorders internationally (Pringsheim et al., 2014). In the context of increasing life expectancies globally, a steady increase in PD is [...]

Purpose: Ultrasound imaging offers a noninvasive adjunct to clinical swallowing assessment. Published reliability of sophisticated ultrasound systems is promising; however, no data exist for reliability using more affordable, pocket-sized devices. This study explored intrarater, interrater, and test-retest reliability of swallowing measures acquired with pocket-sized ultrasound technology. Method: Five participants collected measures of swallowing from 20 healthy individuals using the Clarius ultrasound. Hyoid excursion and thyrohyoid approximation were derived during saliva, liquid, and puree swallowing. The cross-sectional area of the floor of mouth muscles and tongue thickness were obtained at rest. Measures were collected at two occasions minimum 11 days apart. Reliability was assessed for the entire process of data acquisition including scanning and online measurement, and for offline measurement of saved images. Results: For most measures, reliability was poor (ICC [intraclass correlation coefficient] < .50) to moderate (ICC = .50-.75) for the entire process of data acquisition and poor to good (ICC > .75) when measuring saved images. Conclusion: Further work is needed to elucidate whether our study findings apply to the Clarius system only or the data suggest a general limitation of pocket-sized ultrasound technology., Imaging techniques play a critical role in the assessment of swallowing. Compared to the commonly performed videofluoroscopic swallowing study, ultrasound imaging is a radiation-free procedure. As an adjunct to swallowing [...]

Purpose: The aim of this study was to examine the relationships of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics and swallowing safety in a heterogenous group of dysphagic adults. Method: A retrospective analysis was completed of videofluoroscopic swallow studies of consecutive dysphagic outpatient adults presenting to a tertiary swallowing center from January 1, 2015, to December 31,2017. Videofluoroscopic swallow study records were included if containing displacement swallowing kinematics of a 20-ml single liquid swallow and clinical measures of anterior (L-MIPA) or posterior (L-MIPP) lingual maximal isometric press, saliva mean swallowing pressures (S-MSP), and/or open mouth-maximal isometric press (OM-MIP). Regression analyses were used to examine the relationships between clinical measures of lingual (L-MIPA, L-MIPP, S-MSP) and perihyoid (OM-MIP) strength and displacement swallowing kinematics, and binomial logistic regressions were used to examine the relationships between clinical measures of lingual and perihyoid strength and swallowing safety (Penetration-Aspiration Scale [PAS]). Results: Multivariate regressions revealed significant relationships of L-MIPA, L-MIPP, S-MSP, and OM-MIP with group-level changes to the displacement swallowing kinematics. Univariate analyses revealed significant relationships of L-MIPA and L-MIPP with pharyngeal constriction ratio, maximal extent of upper esophageal segment opening, and PAS. Conclusions: Weak relationships were identified of clinical measures of lingual and perihyoid strength with displacement swallowing kinematics. These findings suggest that clinical measures of lingual and perihyoid strength do not fully explain impairments in swallowing kinematics across a heterogenous group of dysphagic patients. Weak-to-moderate relationships were identified between clinical measures of lingual strength and PAS, suggesting that they may have value in predicting functional measures of swallowing safety. Further research is needed to examine how findings may differ between specific patient populations., Identifying appropriate exercises for dysphagia rehabilitation requires a thorough understanding of the pathophysiologies (altered anatomy, peripheral sensation, somatosensory processing, motor coordination, peripheral muscle strength) that underly changes to normal swallowing [...]

Purpose: The purpose of this study was to explore the impact of anterior cervical discectomy and fusion (ACDF) with anterior instrumentation on swallowing function and physiology as measured on videofluoroscopic swallowing studies. Method: We retrospectively analyzed both functional measures (penetration-aspiration, residue) and physiological/ anatomical measures (hyoid excursion, posterior pharyngeal wall thickness) in a series of 17 patients (8 men, 9 women, mean age 54 years). These measures were extracted from calibrated 5-ml boluses of thin radio-opaque liquids on both pre-ACDF and post-ACDF videofluoroscopies, thus controlling for individual variation and protocol variation. Results: After ACDF surgery, we found significant within-subject worsening of Penetration-Aspiration Scale (Rosenbek, Robbins, Roecker, Coyle, & Wood, 1996) scores, vallecular (but not piriform sinus) residue, superior (but not anterior) hyoid excursion, and posterior pharyngeal wall thickness. Results are discussed in the context of previous literature. Conclusions: ACDF surgery can affect both physiological/ anatomical and functional measures of swallowing. Future research should expand to other biomechanical and temporal variables, as well as greater bolus volumes and a wider array of viscosities and textures, Anterior cervical discectomy and fusion (ACDF) is routinely conducted in response to clinically symptomatic soft or hard compression of a nerve root or the spinal cord that results in radiculopathy [...]

Purpose: In the present study, the authors investigated lingual propulsive pressures generated in the normal swallow by the anterior and posterior lingual segments for various consistencies and maximum isometric tasks. Method: Lingual pressures for saliva, thin, and honey-thick liquid boluses were measured via the Iowa Oral Performance Instrument (IOPI Medical, Carnation, WA) at both anteromedian and posteromedian lingual segments of 62 healthy participants, ages 18-34 years (30 men, 32 women). Results: A repeated-measures analysis of variance revealed that all lingual swallowing pressures were significantly greater at the anteromedian segment than at the posteromedian segment. Gender was not a significant factor; however, women exhibited greater swallowing pressures across all conditions. Lingual pressures increased as bolus viscosity increased. No significant interactions existed. Analysis of a subset of 30 participants revealed that men exhibited greater maximal isometric pressure at the anteromedian segment than women, with no significant gender difference at the posteromedian segment. A significantly higher percentage of maximum isometric tongue pressure was exerted by the posteromedian tongue than by the anteromedian tongue. Conclusion: Findings suggest that greater amplitudes of lingual pressures are generated during normal swallowing at the anteromedian lingual segment; however, a greater percentage of maximum isometric tongue pressure was exerted by the posteromedian lingual segment, suggesting increased effort by the posterior tongue during bolus propulsion. Key Words: lingual pressures, bolus propulsion, anterior, posterior, tongue, The tongue is integral in normal swallowing function, as it generates pressure to propel the bolus through the oral cavity and pharynx (McConnel, 1988; Robbins, Levine, Wood, Roecker, & Luschei, [...]

A better understanding of the central control of the physiology of deglutition is necessary for devising interventions aimed at correcting pathophysiological conditions of swallowing. Positive modulation of the cortical swallowing network can have clinical ramifications in dysphagia due to central nervous system deficits. Our aim was to determine the effect of nutritive sensory input on the cortical swallowing network. In 14 healthy right-handed volunteers, we utilized a paradigm-driven protocol to quantify the number of activated voxels and their signal intensity within the left hemispheric cortical swallowing network by high-resolution functional MRI (fMRI) during five different swallowing conditions. Swallowing conditions included a dry swallow (saliva) and natural water-, lemon-, popcorn-, and chocolate-flavored liquid swallows. Each flavored liquid was presented simultaneously by its image, scent, and taste in random order and tested over three runs. fMRIs were analyzed in a blinded fashion. Average fMRI blood oxygenation level-dependent signal intensity and number of activated voxels during swallowing concurrent with nutritive gustatory, olfactory, and visual stimulations were significantly increased compared with dry/natural water swallows throughout the cortical swallowing network (P < 0.001 and P < 0.05, respectively). Subregion analysis showed the increased activity for flavored liquids in prefrontal, cingulate gyms, and sensory/motor cortex, but not in precuneus and insula. Concurrent gustatory, olfactory, and visual nutritive stimulation enhances the activity of the cortical swallowing network. This finding may have clinical implications in management of swallowing disorders due to cortical lesions. flavor; deglutition; olfaction; gustation doi: 10.1152/ajpgi.00161.2010.

Purpose: To examine the application of known muscle training principles to tongue strengthening exercises and to answer the following research questions: (a) Did lingual strength increase following 9 weeks of training? (b) Did training conducted using an exercise moving the tongue in one direction result in strength changes for tongue movements in other directions? (c) Were differential training effects observed for participants completing exercises sequentially (in isolation) versus concurrently (several exercises in combination)? (d) Were strength gains maintained after exercise was discontinued? Methods: Participants were 39 healthy adults assigned to sequential or concurrent lingual strength training. Lingual exercise (elevation, protrusion, and/or lateralization) was conducted for 9 weeks, with lingual strength and cheek strength (control variable) assessed weekly. Results: All lingual strength measures increased with training, but cheek strength remained unchanged. Training effects were not related to training condition (sequential vs. concurrent), nor were specificity effects observed for direction of exercise. Significant decreases in lingual strength were noted 2-4 weeks after exercise was discontinued. Conclusions: The findings replicate those of earlier studies demonstrating that lingual strength may be increased with a variety of exercise protocols and confirm that detraining effects may be observed when training is discontinued. The findings further suggest that the lingual musculature may demonstrate less dramatic training specificity than what has been reported for skeletal muscles. KEY WORDS: oral motor exercise, tongue strength, specificity, detraining, Oral motor exercise (OME) for the purpose of improving speech and swallowing function is a widely used clinical practice in speech-language pathology (Lof & Watson, 2008). Examples of nonspeech OME [...]

Purpose: This study examined the relationship between swallowing and lung volume initiation in healthy adults during single swallows of boluses differing in volume and consistency. Differences in lung volume according to respiratory phase surrounding the swallow were also assessed. Method: Nine men and 11 women between the ages of 19 and 28 years served as study participants. Lung volume and respiratory phase data were recorded as each participant completed 5 trials each of 10-mL and 20-ml. water boluses by cup, and thin and thick paste boluses by spoon, presented in randomized order. Results: Significant differences in lung volume at swallow initiation were found based on bolus consistency but not on bolus volume. No differences were found for lung volume initiation based on the respiratory phase surrounding the swallow or for the respiratory pattern based on bolus volume or consistency. Conclusion: Findings of this study extend the existing knowledge base regarding the interaction of the swallow and respiratory systems by identifying targeted lung volumes at swallow initiation. In addition to other swallow-related biomechanical events and respiratory phase relationships surrounding a swallow, the lung volume at swallow initiation may be an important consideration when investigating swallow physiology and physiopathy. KEY WORDS: swallowing, respiration, swallow motor control, swallow-respiratory integration, Deglutition and respiration share the upper aerodigestive tract, which necessitates the utilization of protective mechanisms to prevent airway compromise during a swallow (Miller, 1982, 1993). Thus, normal coordination between the [...]

In healthy subjects, a close temporal correlation exists between contractions of the circular muscle (CM) and longitudinal muscle (LM) layers of the esophagus. Patients with nutcracker esophagus show disassociation between the peak of contractions of the CM and LM layers and the peak of contraction 1-3 s apart (Jung HY, Puckett JL, Bhalla V, Rojas-Feria M, Bhargava V, Liu J, Mittal RK. Gastroenterology 128:1179-1186, 2005). The purpose of the present study was to evaluate the effect of acetylcholinesterase inhibitor (edrophonium) and acetylcholine receptor antagonist (atropine) on human esophageal peristalsis in normal subjects. High-frequency intraluminal ultrasound imaging and manometry were performed simultaneously during swallow-induced peristalsis in ten normal subjects. Standardized 5-ml water swallows were recorded 2 cm above the lower esophageal sphincter under three study conditions: control, edrophonium (80 [micro]g/kg iv), and atropine (10 [micro]g/kg iv). A close temporal correlation exists between the peak pressure and peak wall thickness during the control period. The mean time lag between the peak LM and peak CM contraction was 0.03 s. After edrophonium administration, the mean contraction amplitude increased from 101 [+ or -] 9 mmHg to 150 [+ or -] 20 mmHg (P < 0.05) and mean peak muscle thickness increased from 3.0 [+ or -] 0.2 mm to 3.6 [+ or -] 0.3 mm (P < 0.01), and duration of both CM and LM contractions were also increased. Furthermore, the mean time difference between the peak LM and CM was increased to 1.1 s, (ranging 0.2 to 3.4 s) (P < 0.0001). We conclude that cholinomimetic agent induces discoordination between the two muscle layers of the esophagus. spastic motor disorders; disassociation; swallow; peristalsis

Swallowed volumes in the fetus are greater than adult values (per body weight) and serve to regulate amniotic fluid volume. Central ANG II stimulates swallowing, and nonspecific ANG II receptor antagonists inhibit both spontaneous and ANG II-stimulated swallowing. In the adult rat, AT 1 receptors mediate both stimulated drinking and pressor activities, while the role of AT2 receptors is controversial. As fetal brain contains increased ANG II receptors compared with the adult brain, we sought to investigate the role of both AT1 and AT2 receptors in mediating fetal swallowing and pressor activities. Five pregnant ewes with singleton fetuses (130 [+ or -] 1 days) were prepared with fetal vascular and lateral ventricle (LV) catheters and electrocorticogram and esophageal electromyogram electrodes and received three studies over 5 days. On day 1 (ANG II), following a 2-h basal period, 1 ml artificial cerebrospinal fluid (aCSF) was injected in the LV. At time 4 h, ANG II (6.4 [micro]g) was injected in the LV, and the fetus was monitored for a final 2 h. On day 3, AT1 receptor blocker (losartan 0.5 mg) was administered at 2 h, and ANG II plus losartan was administered at 4 h. On day 5, AT2 receptor blocker (PD-123319; 0.8mg) was administered at 2 h and ANG II plus PD-123319 at 4 h. In the ANG II study, LV injection of ANG II significantly increased fetal swallowing (0.9 [+ or -] 0.1 to 1.4 [+ or -] 0.1 swallows/min; P < 0.05). In the losartan study, basal fetal swallowing significantly decreased in response to blockade of AT1 receptors (0.9 [+ or -] 0.1 to 0.4 [+ or -] 0.1 swallows/min; P < 0.05), while central injection of ANG II in the presence of AT1 receptor antagonism did not increase fetal swallowing (0.6 [+ or -] 0.1 swallows/min). In the PD-123319 study, basal fetal swallowing did not change in response to blockade of AT2 receptor (0.9 [+ or -] 0.1 swallows/min), while central injection of ANG II in the presence of AT2 blockade significantly increased fetal swallowing (1.5 [+ or -] 0.1 swallows/min; P < 0.05). ANG II caused significant pressor responses in the control and PD-123319 studies but no pressor response in the presence of AT1 blockade. These data demonstrate that in the near-term ovine fetus, AT1 receptor but not AT2 receptors accessible via CSF contribute to dipsogenic and pressor responses. ovine fetus; angiotensin receptors; swallowing

Recent studies done on healthy older individuals have demonstrated elevated taste thresholds for sweet, sour, and salty taste. At suprathreshold levels, such individuals have also shown less ability to discriminate between different intensities of the same tastant. This study was designed to provide information on swallow timing and muscle contraction intensity variables in healthy older people during swallowing of liquid and cottage cheese consistencies in 3 taste conditions (sweet, sally, and sour). Taste and consistency were incorporated in the design of this study to determine not only the effect of taste and consistency independently, but also the effects of taste and consistency in combination. Surface electromyography (EMG) at 3 sites--the orbicularis oris inferior region, submental muscle region, and infrahyoid muscle region--were included in the study. Results revealed that the start of submental muscle activation was significantly later in older participants than in younger participants. The 3 taste conditions had higher EMG levels and shorter activation times than the no-taste condition, although different taste conditions and different muscle sites were affected differently. With thicker consistency, substantially increased EMG amplitude and duration were noted for all three sites. A more pronounced effect of taste was manifested as earlier submental or infrahyoid muscle activation when the three tastants were added to a thicker consistency. Interaction of taste, consistency, and age was also noted for onset time at the submental and infrahyoid sites. KEY WORDS: taste, consistency, swallowing, healthy older adults, electromyography, By the year 2025, the number of people aged 60 years and above is expected to triple globally from 376 million to 1.21 billion. Most healthy individuals begin to suffer [...]

Lower esophageal sphincter (LES) relaxation and esophageal body inhibition co-occur during esophageal peristalsis but not necessarily during pharyngeal stimulation or transient LES relaxation (tLESR). This study examined these relationships and the impact on reflux. Nine young volunteers were studied. An artificial high-pressure zone (HPZ) was established, and pH was recorded 8 and 5 cm proximal to the LES. Pharyngeal stimulation was by water injection and gastric distension with liquid or gas. Peristalsis, pharyngeal stimulation, and spontaneous events were recorded. Swallowing relaxed the LES in 100% of trials (the HPZ in 80%) and caused no reflux. Pharyngeal stimulation relaxed the LES in two-thirds of trials, had no effect on the HPZ, and caused no reflux. Gastric distension was associated with 117 tLESRs, 48% with acid reflux, and 32% with gas reflux; there was no effect on the HPZ. We conclude that LES relaxation is a necessary but not sufficient condition for reflux. LES relaxation and esophageal body inhibition are independent events that may be concurrent (swallowing) or dissociated (tLESR). esophageal primary peristalsis; transient LES relaxation; gastroesophageal reflux; pharynx; swallow

Objective: To clarify the pathophysiology of dysphagia by electrophysiological methods. Method: Electrophysiological methods related to oropharyngeal swallowing were used to investigate 25 patients with cervical dystonia and 25 age matched [...]

We investigated the mechanisms of airway protection and bolus transport during retching and vomiting by recording responses of the pharyngeal, laryngeal, and hyoid muscles and comparing them with responses during swallowing and responses of the gastrointestinal tract. Five dogs were chronically instrumented with electrodes on the striated muscles and strain gauges on smooth muscles. Retching and vomiting were stimulated by apomorphine (5-10 ug/kg iv). During retching, the hyoid and thyroid descending and laryngeal abductor muscles were activated; between retches, the hyoid, thyroid, and pharyngeal elevating, and laryngeal adductor muscles were activated. Vomiting always occurred during the ascending phase of retching and consisted of three sequential phases of hyoid and pharyngeal muscle activation culminating in simultaneous activation of all recorded elevating and descending laryngeal, hyoid, and pharyngeal muscles. Retrograde activation of esophagus and pharyngeal muscles occurred during the later phases, and laryngeal adductor was maximally activated in all phases of the vomit. During swallowing, the laryngeal adductor activation was followed immediately by brief activation of the laryngeal abductor. We concluded that retching functions to mix gastric contents with refluxed intestinal secretions and to impart an orad momentum to the bolus before vomiting. During retches, the airway is protected by glottal closure, and between retches, it is protected by ascent of the larynx and closure of the upper esophageal sphincter. The airway is protected by maximum glottal closure during vomiting. During swallowing, the airway is protected by laryngeal elevation and glottal closure followed by brief opening of the glottis, which may release subglottal pressure expelling material from the laryngeal vestibule. cricopharyngeus; stylopharyngeus; geniohyoideus; thyroary-tenoideus

Spontaneous fetal swallowing occurs at a markedly higher rate compared with spontaneous adult drinking activity. This high rate of fetal swallowing is critical for amniotic fluid volume regulation. Central NO is critical for maintaining the normal rate of fetal swallowing, as nonselective inhibition of NO (with central [N.sub.G]-nitro-L-arginine methyl ester) suppresses spontaneous and angiotensin II (ANG II)-stimulated swallowing. We sought to differentiate the contributions of central endothelial vs. neuronal NO in the regulation of spontaneous and stimulated fetal swallowing, using a selective neuronal NO synthase (nNOS) inhibitor. Six time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and intracerebroventricular (icv) catheters and electrocorticogram (ECoG) and esophageal electromyogram electrodes and studied at 130 [+ or -] 1 days of gestation. After an initial 2-h baseline period (0-2 h), the selective nNOS inhibitor N-propyl-L-arginine (NPLA) was injected icv (2-4 h). At 4 h, the dose of NPLA was repeated, together with ANG II, and fetal swallowing was monitored for a final 2 h. Four fetuses also received an identical control study (on an alternate day) in which NPLA was replaced with artificial cerebrospinal fluid (aCSF). Suppression of nNOS by icv NPLA significantly reduced mean ([+ or -] SE) spontaneous fetal swallowing (1.35 [+ or -] 0.12 to 0.50 [+ or -] 0.07 swallows/min; P < 0.001). Injection of ANG II in the presence of NPLA had no dipsogenic effect on fetal swallowing (0.68 [+ or -] 0.09 swallows/min). In the aCSF study, icv aCSF did not change fetal swallowing (0.93 [+ or -] 0.10 vs. 0.95 [+ or -] 0.09 swallows/min), whereas icy ANG II resulted in a significant increase in the rate of fetal swallowing (2.0 [+ or -] 0.04 swallows/ min; P [+ or -] 0.001). We speculate that the suppressive dipsogenic effects of central NPLA indicate that spontaneous and ANG II-stimulated fetal swallowing is dependent on central nNOS activity. amniotic fluid; angiotensin II

Mechanical stimulation of the pharyngeal areas readily elicits reflex swallowing. However, it is much more difficult for electrical stimulation of the glossopharyngeal nerve (GPN) to evoke reflex swallowing than it is for stimulation of the superior laryngeal nerve (SLN) to do so. These paradoxical findings remain unexplained; hence, the main purpose of this study was to explain this contradiction by using a urethane-anesthetized rat. Mechanical stimulation easily elicited reflex swallowing from the pharynx. The posterior pillars, posterior pharyngeal wall, and the soft palate of the rat were extremely reflexogenic areas for swallowing. Sectioning the pharyngeal branch of the GPN (GPN-ph), however, eliminated the swallowing reflex from these areas. In contrast, sectioning the lingual branch of the GPN had no effect on the elicitation of swallowing. Electrical stimulation of the GPN-ph and SLN elicited sequentially occurring swallows. The relationship between stimulus frequency and the latency of swallowing for the GPN-ph was approximately the same as that for the SLN. These results indicate that the GPN-ph plays a major role in the initiation of reflex swallowing from the pharynx in rats. superior laryngeal nerve; pharyngeal reflex; deglutition; pharyngeal plexus

Caston-Balderrama, A., M. J. M. Nijland, T. J. McDonald, and M. G. Ross. Intact osmoregulatory centers in the preterm ovine fetus: Fos induction after an osmotic challenge. Am J Physiol Heart Circ Physiol 281: H2626-H2635, 2001.--We previously demonstrated a functional systemic dipsogenic response in the near-term fetal sheep (128-130 days; 145 days = full-term) with swallowing activity stimulated in response to central and systemic hypertonic saline. Preterm fetal sheep (110-115 days) do not consistently demonstrate swallowing in response to hypertonic stimuli, and it is unclear whether this is due to immaturity of osmoreceptor mechanisms or neuronal pathways activating swallowing motor neurons. To determine whether osmoreceptive regions in the preterm fetus are activated by changes in plasma tonicity, we examined Fos expression with immunostaining in these neurons in response to an osmotic challenge. Nine preterm fetal sheep [five hypertonic saline-treated fetuses (Hyp) and four isotonic saline-treated fetuses (Iso)] were prepared with vascular and intraperitoneal catheters. Seventy-five minutes before tissue collection, hypertonic (1.5 M) or isotonic saline was infused (12 ml/kg) via an intraperitoneal catheter to fetuses. Brains were examined for patterns of neuronal activation (demonstrated by Fos protein expression). Hyp demonstrated increases in plasma osmolality (~10 mosmol/kg [H.sub.2]O) and Na concentrations (5 meq/1). Increased Fos expression was detected in Hyp in the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), median preoptic nucleus (MnPO), supraoptic (SON), and paraventricular nuclei (PVN) compared with Iso animals. Neuronal activation within the OVLT, SFO, and MnPO indicates intact osmoregulatory mechanisms, whereas activation of the SON and PVN suggests intact fetal neural pathways to arginine vasopressin neurons. These results suggest that preterm fetal swallowing insensitivity to osmotic stimuli may be due to immaturity of integrated motor neuron pathways. immunocytochemistry; circumventricular organs; thirst; swallowing Received 12 January 2000; accepted in final form 24 August 2001

Submental surface electromyographic recordings are commonly used in the investigation of swallowing disorders. The measured electromyography is thought to reflect the actions of floor-of-mouth muscles. Although this is a reasonable assumption, to date there have been no investigations to delineate which muscles contribute to this surface recording. The primary goal of this experiment was to determine which muscles contribute most to the submental surface. Electromyography was recorded simultaneously from the submental surface as well as from five individual muscles: mylohyoid, anterior belly of the digastric, geniohyoid, genioglossus and platysma. Three analysis methods were performed to estimate individual muscle contributions: correlation, numeric, and analytic. For the numeric and analytic analyses, a linear model was defined and used to represent the relationship between the surface and intramuscular recordings. Muscles that received a high correlation, numeric and/or analytic value were considered to be primary contributors to the submental recording. Regardless of analysis approach, the primary contributions to the submental surface recording were the mylohyoid, anterior belly of the digastric, and the geniohyoid muscles. Contributions from the genioglossus and the platysma muscles were minimal. Contributions as a function of bolus volume and viscosity are also discussed. Keywords: swallowing, oral muscles, electromyography

Single cell activity was recorded for 11 hypoglossal motoneurons controlling the activity of the geniohyoid and the thyrohyoid and the activity of the nerves innervating these muscles in decerebrate cats to determine their activities during swallowing and vomiting. Results reveal that these neurons have airway-protective functions during deglutition and emesis but they do not subserve functions that keep the airway open.

Research was conducted to test whether dopamine D1 receptor antagonist influences the swallowing reflex and reduces substance P in the peripheral organs of guinea pigs. A catether was inserted through the mouth of the pigs so that the tip of the catheter lays in the pharynx. The animals were treated with subcutaneous injections of a selective dopamine D1 receptor antagonist. Results suggested that inhibition of the dopamine D1 receptor may impair the swallowing reflex and reduce substance P content in the peripheral organs.

The effects of trigeminal and vagus nerve stimulation on the oropharynx and esophagus was analyzed to determine the role of the cranial nerves in the modulation of esophageal and pharyngeal muscles. Two distinct pharyngoesophageal responses were elicited in human oropharynx and esophagus by the electromagnetic stimulation of the suborbital branch of the trigeminal and vagus nerves. The pharyngoesophageal response to afferent stimulation was also mediated by the neurons of the brain stem swallowing center.

The inhibitory effects of pharyngeal water stimulation on esophageal peristalsis induced by swallowing different volumes of liquid and semisolid boluses was analyzed in nine healthy human volunteers. Analysis of esophageal bolus transport during dry, water and mashed potato swallows in human subjects indicated the inhibition of peristalsis during swallowing. Furthermore, sensory impulses originating from the pharynx stimulated by minute injections of water inhibited esophageal bolus transit.

The respiratory motor responses of the superior laryngeal nerve (SLN) and the pharyngeal branch of vagus (X) were analyzed in rats and cats during short latency excitations by SLN stimulation. The rats and cats exhibited different qualitative reflex responses during the stimulation of X and SLN due to the paucity of the bulbospinal respiratory neurons of the rats. Furthermore, the cats exhibited dysinaptic excitation in response to SLN stimulation in the contralateral phrenic nerve which is not present in rats.

In contrast to adult humans, the epiglottis of other mammals and infant humans is situated close to the soft palate. It has been argued that this posture is maintained during swallowing, with food passing laterally around an intact airway. To test this supposition, the movement of the epiglottis in two contrasting mammalian species, pigs and ferrets, was studied by placing radiopaque markers on the epiglottis and soft palate. Swallowing was observed with videofiuoroscopy while the animals were feeding on hard and soft foods, liquids, and food mixed with barium sulfate. Analysis of the images showed that bolus formation and downward movement of the epiglottis away from the soft palate were unvarying phenomena in both animals for all tested foods. The duration of the epiglottic movement was approximately 0.3 s for liquids and slightly longer for solids. Because swallowing never occurred past an upright epiglottis, the results of this study do not support the hypothesis that adult animals maintain a patent airway during swallowing. Instead, the epiglottis in nonhuman mammals downfolds similarly to that of adult humans during swallowing.

Previous studies have suggested the role of the valleculae in swallowing, but the mechanism underlying this event has not been elucidated. Eight healthy subjects were studied to investigate the functions of the valleculae and determine the parameters that modulate the elicitation of protective swallows in response to fluid infusion. The results showed that the valleculae act to contain pharyngeal secretions before swallowing. Volitional control was unaffected by taste or temperature.

A study was conducted to examine the effect of gravity and body position on bolus flow through the pharynx and upper esophageal sphincter (UES) during normal oropharyngeal swallowing. Videography and manometry were used to measure UES pressure and pharyngeal pressure in three different body positions: upright, horizontal and inverted. The results revealed that body position has no effect on the movement of bolus during swallowing. However, it was shown that altering body position increases residual opening capacity.

Background. Tongue activity plays a crucial role in both oral and pharyngeal phases of swallowing. In this study, maximum lingual isometric and swallowing pressures were quantified in two groups of healthy men to investigate possible age effects on performance. Magnetic resonance images of the brain were also obtained to examine the relationship between age-related anatomical changes and swallowing function. Methods. Pressures were recorded at three lingual sites (tip, blade, and dorsum) during a maximal isometric task and during saliva swallows. Task order was randomized, and subjects performed three trials per placement site. Additionally, t2-weighted MRIs were obtained on 9 of the 10 young subjects (mean age = 25 years) and all 15 older subjects (mean age = 75 years). Results. Maximal isometric pressures were significantly greater for younger subjects at the tongue blade site (p = .002), whereas peak swallowing pressures remained similar across both age groups. Within-subject comparisons of maximum isometric to swallowing pressures, a measure of reserve capacity, revealed reduced difference scores at the tongue blade in the older group (p = .02). Older subjects exhibited significantly more cerebral atrophy (p = .001) and greater incidence of periventricular white matter lesions (p = .0001) than did younger subjects. Conclusions. While swallowing pressures remain similar across the life span, overall pressure reserve declines with age. The implications are: (a) older people may be working harder to produce adequate swallowing pressures, and (b) age-related illness may put geriatric patients at higher risk for dysphagia, thus further complicating recovery.

Given the relationship between hyoid displacement and aspiration, a simple, accurate, clinically useful method for identification of reduced hyoid displacement is needed. The purpose of this investigation was to validate a quantitative method for clinically assessing hyoid bone movement during swallowing. Videofluoroscopic evaluations of 20 male subjects - 10 who had been subjectively assessed as demonstrating normal hyoid displacement during swallowing, and 10 who had been subjectively assessed as demonstrating reduced displacement during swallowing - were analyzed. A video measuring gauge was used, and a software spreadsheet was developed to perform trigonometric calculations for determination of anterior/superior hyoid trajectories. Statistically significant differences were found between groups in both the anterior and superior directions of hyoid movement. No significant differences were found between liquid and paste swallows within groups. This method is simple in that it is necessary to identify only three to five points on two video images. Those values are then input onto a preprogrammed spreadsheet that automatically performs the necessary calculations. Although the present investigation focused on the movements of the hyoid bone during swallowing, this method of tracking displacement can be used for virtually any task or structure whose movements can be captured on videotape. KEY WORDS: deglutition, hyoid bone, dysphagia, assessment, instrumentation

Seven subjects in the age group of 26-39 were observed to study the mechanism of nasopharyngeal closure (NPC) and its temporal relationship with other biomechanical events during swallowing and belching using concurrent videoendoscopic, videofluoroscopy and manometric techniques. The mechanism of NPC differs during swallowing and belching. NPC has two tiers of closure, palatal elevation and superior pharyngeal muscle adduction, but during belching only palatal elevation occurs.

A study of the physiology of pharyngeal and cervical esophageal swallow in barium meal-fed domestic cats using videofluorography and electromyography reveals a prolonged oral stage of swallow and a faster pharyngeal phase. Constrictor bulge during the beginning of the pharyngeal contractile wave and peristaltic wave summation in the esophagus is greater than that in human adults. Cats resemble human infants, more than human adults, in their swallow physiology.

The oropharyngeal swallow of 10 patients with mild dysphagia at 3 weeks after a cerebrovascular accident (stroke), 10 normal subjects, and 8 neurologically impaired patients with moderate to severe dysphagia was studied videofluorographically to examine the effects of 2 bolus temperatures (room temperature and 33 [degrees] F), 2 volumes, and 2 viscosities on the durations of pharyngeal stage swallow events and the frequency and nature of oropharyngeal swallowing problems and bolus transit. Normal subjects exhibited significantly longer pharyngeal response times and longer laryngeal elevation only for 1 ml cold liquid. The stroke patients and the 8 significantly dysphagic neurologically impaired patients exhibited very few significant effects of temperature on swallowing disorders or swallow measures. Increases in bolus volume and viscosity decreased pharyngeal delay times in both neurologically impaired patient groups. Stroke patients exhibited significantly longer pharyngeal delay times but shorter pharyngeal response times, laryngeal closure, cricopharyngeal opening, and laryngeal elevation than normal subjects on some bolus volumes and viscosities. Results are discussed in terms of the potentially therapeutic effects of bolus volume and viscosity. KEY WORDS: swallowing, bolus volume, temperature, videofluoroscopy, pharynx

Simultaneous videoradiographic and manometric studies of the potential influence of mucosal sensory receptors on the regulation of oral-pharyngeal swallow events show that mucosal sensory receptors exert no influence in eliciting the pharyngeal swallow response and in the temporal regulation of swallow events. Sensory input from oral-pharyngeal mucosa influences the pharyngeal contraction duration. Application of mucosal anesthesia leads to the absence of aspiration during deglutition.

A scintigraphic method facilitates the examination of the influence of age on pharyngeal and oral transit and clearance of bolus during swallowing. It is indicated that there is a significant increase in the times of pharyngeal clearance, pharyngeal transit and oral transit as a result of ageing. There is also an enhancement in the time of glottis' exposure to the swallowed bolus.

Speech and swallowing function was examined in 11 patients who underwent surgical resection of greater than 1 cm of tongue base, tonsil, and faucial arch with mandible resected on the side of the tumor and reconstruction by primary closure. Preoperatively and 1 and 3 months post-healing, high fidelity audio recordings were made of a 6- to 7-minute conversational speech sample, the sentence version of The Fisher Logemann Test of Articulation Competence was administered, and videofluoroscopic assessment of oropharyngeal swallow was conducted. All subjects exhibited changes in speech and swallowing function postoperatively, with little improvement during the study. Patients exhibited greatest difficulty on stop and fricative consonants and bolus propulsion. Comparison with patients who received anterior tongue and floor of mouth resections and distal flap reconstruction revealed consistently better speech performance by the tonsil/base of tongue patients, although the same phonemes were affected. Swallow function was equally affected in the two groups. Results are discussed in terms of locus of surgical resection, nature of reconstruction, and need for swallowing therapy.

Three dogs were utilized in the investigation of the magnetic induction of brain electrical stimulation to promote swallowing and contraction of the upper esophageal sphincter (UES). Results show that stimulation of the cerebral cortex induces swallowing and contration of the UES. The response was also demonstrated to be proportional tothe strength of the stimulus. Sensory stimulation of the pharyngeal area potentiated the effect of cerebral cortex stimulation.

During normal swallowing, a progressive wave of muscular relaxation and contraction (peristalsis) propels food through the esophagus to the stomach. A painful swallowing disorder known as diffuse esophageal spasm (DES) occurs in a small number of patients. Definitive criteria for DES are not agreed upon (although high-amplitude esophageal contractions are often used as a diagnostic marker), and the prevalence of this condition is not fully known. To further characterize DES, the records of 1,480 patients who were referred for evaluation of chest pain and difficulty swallowing, and who underwent esophageal manometry (recording of intraesophageal pressure changes during swallowing) were reviewed. A diagnosis of DES was made when more than 10 percent but less than 100 percent of the esophageal contractions during swallows were simultaneous (i.e. not peristaltic). According to this criterion, 56 of the patients (4 percent) were diagnosed with DES. Of these 56 patients, only two (4 percent) showed evidence of high-amplitude esophageal contractions; in both cases these were peristaltic contractions. No patient showed evidence of high-amplitude simultaneous contractions; simultaneous contractions were uniformly of lower amplitude than peristaltic contractions. Excessively high pressure of the lower esophageal sphincter (LES), the muscular ring separating the esophagus from the stomach, was found in 5 of the 56 DES patients (9 percent); poor relaxation of the LES during swallowing was found in 7 of the 56 patients (13 percent). Hence, DES is a rare finding based on manometric diagnosis and among those patient with confirmed DES, the occurrence of high-amplitude contractions is also rare. (Consumer Summary produced by Reliance Medical Information, Inc.)

During normal deglutition (swallowing), a progressive wave of muscular relaxation and contraction (peristalsis) propels food through the esophagus to the stomach. The lower esophageal sphincter (LES), a muscular ring separating the esophagus from the stomach, transiently relaxes, allowing ingested food to enter the stomach. In the painful condition known as esophageal achalasia, there is excessive contraction of the esophageal musculature, often with a failure of the LES to relax. This leads to discomfort during swallowing (dysphagia). Relaxation of the LES is mediated by nerve fibers running through the esophageal wall which release, among other neurotransmitters, vasoactive intestinal polypeptide (VIP). It has been reported that patients with esophageal achalasia have reduced numbers of esophageal VIP-containing fibers. Low-frequency electrical stimulation of the esophageal nerves through the skin, transcutaneous electrical nerve stimulation (TENS), ameliorates the symptoms of esophageal achalasia, possibly by stimulating the release of VIP. To evaluate this hypothesis, a study was carried out with six patients suffering from achalasia (five females and one male) who were underwent 45-minute daily TENS sessions over a one-week period. LES pressure and blood VIP levels were measured prior to the first TENS session, and at the conclusion of the week of stimulation sessions. At the end of the treatment period, LES pressure was significantly reduced compared with the pretreatment time point, whereas VIP levels were significantly increased. Hence, TENS may effect its therapeutic action in esophageal achalasia by inducing a VIP-mediated relaxation of the esophageal musculature. (Consumer Summary produced by Reliance Medical Information, Inc.)