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PubMed2005

Bolus location at the initiation of the pharyngeal stage of swallowing in healthy older adults.

This study characterized the vertical position of the bolus head at the onset of the pharyngeal swallow in healthy older adults. Lateral-view videofluoroscopic (VF) images were obtained from ten healthy volunteers (age-71.6 +/- 7.5 years, mean+/- SD) as they swallowed 5-cc thin liquid barium aliquots. For each swallow, the bolus head and several anatomic landmarks were digitally recorded from the image in which pharyngeal swallow-related hyoid bone elevation began. Vertical distance between the bolus head and the intersection of the tongue base and mandibular ramus (TMI) was computed. Bolus head position at swallow onset ranged from 47.4-mm above to 34.9-mm below the TMI (2.2 +/- 14.4-mm, mean +/- SD). Although the bolus head was below the level of the TMI for the majority of swallows, neither penetration nor aspiration occurred. For individual subjects, mean bolus head position ranged from 25.8 +/- 5.0-mm above to 15.5 +/- 6.5-mm below the TMI. Whereas five of ten subjects initiated the pharyngeal swallow with the bolus head consistently above or consistently below the TMI, five subjects initiated swallowing with the bolus head either above or below the TMI across trials. Older adults commonly initiate thin-liquid swallows with the bolus head well below the TMI without associated penetration or aspiration. Thus, bolus position alone does not differentiate between normal and pathologic swallowing within the healthy elderly. Bolus position at pharyngeal swallow onset can vary substantially from trial to trial within an individual, suggesting that the triggering of swallowing depends on multiple influences.

Aged↗
PubMed1994

Swallowing of lung liquid and amniotic fluid by the ovine fetus under normoxic and hypoxic conditions.

OBJECTIVE: The lungs of the mammalian fetus secrete large volumes of fluid daily. The purpose of this study was to estimate the fraction of the lung liquid that is swallowed as it exits the fetal trachea versus that which enters the amniotic fluid under normoxic and hypoxic conditions. STUDY DESIGN: In chronically catheterized fetal sheep at 119 to 133 days' gestation the volume of fluid swallowed by the fetus was monitored five times per day for three consecutive 24-hour periods: control, hypoxia, and recovery. The Na+, K+, and Cl- concentrations of the swallowed fluid, lung liquid, and amniotic fluid were measured simultaneously. The fraction of the swallowed fluid that originated from the lungs or amniotic fluid was calculated from 24-hour average compositions and the assumption that the fetus swallowed only amniotic fluid and lung liquid. RESULTS: During the control, hypoxia, and recovery periods the fetuses swallowed 264 +/- 43 (SE), 92 +/- 23, and 271 +/- 24 ml/kg of fetal weight per day, respectively. As determined from Cl- concentrations, this swallowed fluid was composed of 17.7% +/- 2.7%, 24.8% +/- 5.8%, and 11.9% +/- 3.4% lung liquid, respectively, with the remainder being amniotic fluid. Throughout the three 24-hour observation periods there was an inverse relationship between the net 24-hour swallowed volume and the fraction of the swallowed fluid that originated from the lungs. Calculations based on Na+ concentrations yielded essentially the same results with slightly more scatter, whereas calculations based on K+ concentrations were unreliable. CONCLUSIONS: (1) Chloride concentrations provide the best of the three index values for a compositional analysis of fluids swallowed by the fetus. (2) Under normoxic conditions around 18% of swallowed fluid is derived from the fetal lungs. (3) On the basis of published fluid secretion rates for the fetal lung, an average of 50% of the liquid that exits the fetal trachea is swallowed and the rest mixes with the amniotic fluid.

Amniotic Fluid↗
PubMed1986

Effect of catecholamines on the swallowing reflex after pressure microinjections into the lateral solitary complex of the medulla oblongata.

The present study was carried out to elucidate the influence of catecholamines on swallowing, a polysynaptic reflex organized by an interneuronal network localized mainly within the lateral solitary complex (LSC) of the medulla oblongata. The effects of catecholaminergic agents were investigated in the rat, on rhythmic swallowing elicited by repetitive stimulation of the superior laryngeal nerve (SLN). Catecholaminergic agents were microinjected by pressure application, through multibarrelled glass micropipettes, into the LSC including the tractus solitarius, the swallowing region of the nucleus of the solitary tract and the adjacent reticular formation. Microinjections of noradrenaline (NA, 0.1-5 nmol, 50 nl) induced a significant decrease of the number and the amplitude of the rhythmic swallows elicited by stimulation of the ipsilateral SLN. This inhibitory effect was dose-related. Microinjections of clonidine (2.5 nmol, 50 nl), dopamine (0.25-2.5 nmol, 50 nl) and apomorphine (0.5 nmol, 50 nl), also inhibited swallowing. No significant modification of swallowing was induced by control injections of the vehicle (50 nl) within the active sites. Moreover the NA-induced inhibition of swallowing, was significantly antagonized by pretreatment with the alpha-adrenergic blocker phentolamine applied locally in the LSC. Furthermore neither blood pressure, nor respiratory rhythm were consistently modified by the catecholaminergic microinjections, indicating that the catecholamine-induced inhibition of swallowing was not a secondary side effect originating from alteration of these functions. It can therefore be concluded that the present results demonstrate the existence within the LSC of a catecholaminergic inhibition of the swallowing reflex. This inhibitory effect likely arises from activation of specific catecholaminergic receptors and affects the swallowing structures localized within the LSC, i.e., the laryngeal swallowing afferents running in the solitary tract and/or the swallowing interneurons within the nucleus of the solitary tract.

Animals↗
PubMed2004

Swallowing threshold and masticatory performance in dentate adults.

A variety of both natural and artificial foods are commonly used for the evaluation of masticatory function. We compared swallowing thresholds of three natural foods (peanuts, cheese and carrots) to those of a standardized artificial test food (Optocal Plus) and examined the relationship between masticatory performance and the swallowing threshold. Eighty-seven healthy dentate subjects participated (25 men and 62 women, aged 42.0+/-12.1 years). We evaluated the dental state, registered the number of chewing strokes used before swallowing, analyzed the chewed particles and determined median particle sizes (X50) for Optocal Plus after 15 chewing strokes and at the moment of swallowing. The results show that the number of strokes used before swallowing each natural food linearly increased with volume (P<0.001), and that carrots required more strokes than peanuts and cheese (P<0.001). The number of chewing strokes used before swallowing Optocal Plus was comparable to the number used for carrots. Masticatory performance was significantly influenced by dental state, but not by age or gender. Significant correlations were observed for: (1) the number of chewing strokes used before swallowing natural foods and Optocal Plus; (2) the median particle sizes after 15 strokes and before swallowing; (3) the number of chewing strokes before swallowing and the corresponding median particle size. However, median particle sizes as obtained after 15 strokes did not correlate with the number of strokes used before swallowing (r=0.02). Thus, bad chewers did not necessarily chew longer before swallowing than good chewers. As a consequence bad chewers would, on average, swallow larger food particles.

Adult↗
PubMed1997

Anticholinergic suppression of ovine fetal swallowing activity.

OBJECTIVE: Fetal swallowing contributes importantly to amniotic fluid volume regulation as the primary route of fluid resorption, reaching 500 to 1000 ml/day near term. Near-term ovine fetal swallowing activity occurs predominantly during low-voltage electrocortical activity. In view of the potential to pharmacologically alter electrocortical activity, we hypothesized that fetal administration of a centrally acting cholinergic antagonist may be used to modulate fetal swallowing activity. To explore cholinergic modulation of swallowing activity, we examined fetal swallowing and electrocortical activity in response to central and peripheral cholinergic suppression by atropine sulfate. STUDY DESIGN: Singleton ovine fetuses (n = 6) were chronically prepared with vascular catheters and thyrohyoid, nuchal, and thoracic esophageal electromyogram and biparietal electrocortical electrodes. Swallowing and electrocortical activity were monitored for 2 hours before and after intravenous injection (1 ml of 0.15 mol/L sodium chloride) of atropine sulfate (1 mg/kg). On a subsequent day an identical study was performed with use off atropine methyl nitrate (3 mg/kg), an atropine analog that does not cross the blood-brain barrier. RESULTS: Atropine sulfate decreased low-voltage electrocortical activity (56% +/- 5% to 14% +/- 4%), increased high-voltage electrocortical activity (40% +/- 5% to 81% +/- 5%), and did not change intermediate electrocortical activity (4% +/- 1% to 5% +/- 1%). Fetal swallowing activity decreased from 46 +/- 12 to 12 +/- 2 swallows per hour after atropine sulfate administration. Atropine methyl nitrate had no discernible effect on either fetal electrocortical or swallowing activity. Fetal arterial pressure, plasma osmolality, pH, PCO2, and PO2 did not change. CONCLUSIONS: Central cholinergic antagonism suppresses low-voltage fetal electrocortical and swallowing activity in the ovine fetus. Studies exploring spontaneous or induced fetal swallowing should consider the behavioral state of the fetus when conclusions are drawn about changes in the swallowing activity.

Animals↗
PubMed1999

Swallowing disorders in severe brain injury: risk factors affecting return to oral intake.

OBJECTIVE: To determine the incidence and type of swallowing disorders that accompany severe brain injury and to identify factors that affect oral intake. DESIGN: Inception cohort study. SETTING: Level I trauma center. PATIENTS: Consecutively admitted patients with severe brain injury who achieved cognitive levels during admission to assess swallowing and who did not sustain injuries preventing swallowing assessment (n = 54). MAIN OUTCOME MEASURES: Type of swallowing abnormalities and presence of aspiration evident on videofluoroscopic swallow studies (VFSS), days to initiation and achievement of oral feeding, ventilation days, presence of a tracheostomy, and cognitive levels at initiation and achievement of oral feeding. RESULTS: Sixty-one percent of subjects exhibited abnormal swallowing. Loss of bolus control and reduced lingual control occurred most commonly. Aspiration rate was 41%. Normal swallowers achieved oral feeding in 19 days versus 57 days for abnormal swallowers. Rancho Los Amigos (RLA) Level IV was needed for initiation of oral feeding; Level VI was needed for total oral feeding. Risk factors for abnormal swallowing included: lower admission Glasgow Coma Scale (GCS) and RLA scores, presence of a tracheostomy, and ventilation time longer than 2 weeks. Risk factors for aspiration were lower admission GCS and RLA scores. CONCLUSIONS: Swallowing disorders and behavioral/cognitive skills are frequently present in patients with severe brain injury and significantly affect oral intake of food. Persons who swallow abnormally take significantly longer to start eating and to achieve total oral feeding, and they require nonoral supplementation three to four times longer than those who swallow normally.

Adolescent↗
PubMed2001

Effects of central angiotensin II receptor antagonism on fetal swallowing and cardiovascular activity.

OBJECTIVE: Fetal plasma angiotensin II levels are 10 times the levels found in adults. Despite these high levels, central injection of angiotensin II may stimulate fetal swallowing and increase fetal arterial blood pressure. We postulated that the high rate of spontaneous fetal swallowing and normal fetal pressor regulation may be dependent, in part, on central angiotensin II. In view of the potential dipsogenic role of both type 1 and type 2 angiotensin II receptors, we examined the central effect of the nonselective angiotensin II receptor antagonist saralasin on fetal swallowing and cardiovascular responses. STUDY DESIGN: Six time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and intracerebroventricular catheters, electrocorticograms, and esophageal electromyogram electrodes and studied at 130 +/- 1 days' gestation. After an initial 2-hour baseline period (0 to 2 hours), saralasin (1 mL, 64 microg) was injected intracerebroventricularly (2 to 4 hours). After 4 hours the dose of saralasin was repeated together with angiotensin II (1 mL, 6.4 microg), and the fetuses were monitored for a final 2 hours. Four fetuses also underwent an identical control study (on an alternate day) in which saralasin was replaced with artificial cerebrospinal fluid. RESULTS: Blockade of central angiotensin II receptors by intracerebroventricular saralasin significantly reduced mean (+/- SEM) spontaneous fetal swallowing (1.3 +/- 0.1 to 0.4 +/- 0.1 swallows per minute; P <.001) but did not alter fetal mean blood pressure (50 +/- 5 versus 56 +/- 5 mm Hg). Intracerebroventricular angiotensin II, in the presence of saralasin, did not affect swallowing (0.6 +/- 0.1 swallows per minute) or fetal blood pressure. In the control study, intracerebroventricular artificial cerebrospinal fluid did not change fetal swallowing (0.9 +/- 0.1 versus 1.0 +/- 0.1 swallows per minute), whereas intracerebroventricular angiotensin II significantly increased swallowing activity (1.0 +/- 0.1 versus 2.0 +/- 0.1 swallows per minute; P <.001) and fetal blood pressure (51 +/- 2 to 59 +/- 3 mm Hg; P =.003). CONCLUSIONS: Tonic activity of central angiotensin II receptor stimulation contributed to the high rate of basal ovine fetal swallowing but not fetal basal blood pressure. Angiotensin II-mediated fetal dipsogenic and pressor responses are a result of specific angiotensin II receptor binding in central brain regions. These results indicate that fetal exposure to angiotensin II antagonists or angiotensin-converting enzyme inhibitors may have adverse effects on fetal and amniotic fluid homeostasis.

Analysis of Variance↗
PubMed1999

Barium swallows after free jejunal transfer: should they be performed routinely?

Fistula formation after free jejunal transfer for pharyngoesophageal reconstruction is a serious complication with potentially critical consequences. Barium swallow is used postoperatively to check for anastomotic competence before feeding but has been unreliable as a predictor of leak at our institution. The objective of this study was to evaluate the role of routine postoperative barium swallow in 41 consecutive jejunal transfers. Thirty-nine patients who underwent 41 consecutive free jejunal transfers had a routine barium swallow performed between postoperative days 12 and 17. Radiologic findings and clinical outcome were evaluated and correlated. All barium swallows were reviewed by a single experienced radiologist in a blinded fashion. One total and one partial flap failure necessitated a second free jejunal transfer. Pharyngocutaneous fistulae developed after nine free jejunal transfers, of which the barium swallow was normal in four (44 percent) and showed a leak in five (56 percent). In the 32 free jejunal transfers with no clinical leaks, 6 (19 percent) had radiologic leakage of contrast. Thus, barium swallow was normal in 30 patients and showed leakage in 11 patients. Normal barium swallow correlated with uncomplicated clinical course in 26 of 30 cases. In the remaining four cases (13 percent), however, a delayed fistula developed, which was secondary to flap necrosis in one case (negative predictive value 87 percent). On the other hand, radiologic leaks corroborated clinical fistula in 5 of 11 cases (45 percent), whereas no fistula developed in 6 cases (positive predictive value 46 percent). Of the five patients with clinical fistulae, four had early leaks (within 1 week), and the barium swallow did not provide additional information. The fifth patient developed a delayed leak 2 weeks after the barium swallow. Review of these barium swallows at the time of this study reversed the initial report of leakage in three patients, improving the predictive value to 63 percent. These patients had an uncomplicated clinical course. The positive predictive value of clinical assessment alone was 63 percent. We conclude that barium studies following free jejunal transfers can be difficult to interpret, but an experienced radiologist can improve their accuracy. A normal barium swallow, however, does not ensure an uneventful clinical course. Similarly, radiologic leaks do not imply a clinical complication of fistula. Clinical judgment should therefore be exercised in initiating oral intake after free jejunal transfer. Barium swallow should be used only as an adjunct to aid in patient management.

Adolescent↗
PubMed1993

Interaction between central pattern generators for breathing and swallowing in the cat.

1. We examined the interaction between central pattern generators for respiration and deglutition in decerebrate, vagotomized, paralysed and ventilated cats (n = 10), by recording activity from the following nerves: hypoglossal, phrenic, thyroarytenoid and triangularis sterni. Fictive breathing was spontaneous with carbon dioxide above the apnoeic threshold (end-tidal PCO2, 32 +/- 4 mmHg) and fictive swallowing was induced by stimulating the internal branch of the left superior laryngeal nerve (SLN) continuously (0.2 ms pulse duration, 10 Hz). 2. In all ten animals, SLN stimulation evoked short bursts of thyroarytenoid and hypoglossal nerve activity indicative of fictive swallowing. In two of ten animals, respiration was inhibited completely during deglutition. In the other eight animals, fictive breathing and swallowing occurred simultaneously. 3. With SLN stimulation below threshold for eliciting swallowing, the respiratory rhythm decreased, the duration of inspiration did not change but the duration of expiration, especially stage II, increased. Integrated nerve activities indicated that the rate of rise and peak of phrenic nerve activity decreased, stage I expiratory activity of the thyroarytenoid and especially that of the hypoglossal nerve increased and stage II expiratory activity of the triangularis sterni nerve was suppressed completely. However, if inspired carbon dioxide was increased, i.e. hypercapnic ventilation, stage II expiratory activity remained partially during continuous SLN stimulation. 4. Fictive-swallowing bursts occurred only at respiratory phase transitions. At the minimal stimulus intensity that evoked repetitive swallowing bursts, the pattern of interaction between breathing and swallowing central pattern generators was consistent for each animal (n = 7) but was different across animals. In four animals, fictive swallows occurred at the phase transition between stage II expiration and inspiration, at the transition between inspiration and stage I expiration in one animal; and in two other animals, at the transition between stage I and II of expiration. 5. The response to SLN stimulation accommodated during the stimulus train. Accommodation was evident in both the interswallow interval (ISI) which lengthened, and the interaction pattern which had fewer swallows per breath as the stimulus period progressed. In contrast to the ISI, characteristics of the fictive swallow did not accommodate. For example, duration of the swallow was constant, distributed over a narrow range throughout the stimulus train. 6. We conclude that the central pattern generators for swallowing and breathing interact. The pattern of interaction supports the three-phase theory of respiratory pattern generation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

Role of primary sensorimotor cortex and supplementary motor area in volitional swallowing: a movement-related cortical potential study.

We investigated the role of the cerebral cortex, particularly the face/tongue area of the primary sensorimotor (SMI) cortex (face/tongue) and supplementary motor area (SMA), in volitional swallowing by recording movement-related cortical potentials (MRCPs). MRCPs with swallowing and tongue protrusion were recorded from scalp electrodes in eight normal right-handed subjects and from implanted subdural electrodes in six epilepsy patients. The experiment by scalp EEG in normal subjects revealed that premovement Bereitschaftspotentials (BP) activity for swallowing was largest at the vertex and lateralized to either hemisphere in the central area. The experiment by epicortical EEG in patients confirmed that face/tongue SMI and SMA were commonly involved in swallowing and tongue protrusion with overlapping distribution and interindividual variability. BP amplitude showed no difference between swallowing and tongue movements, either at face/tongue SMI or at SMA, whereas postmovement potential (PMP) was significantly larger in tongue protrusion than in swallowing only at face/tongue SMI. BP occurred earlier in swallowing than in tongue protrusion. Comparison between face/tongue SMI and SMA did not show any difference with regard to BP and PMP amplitude or BP onset time in either task. The preparatory role of the cerebral cortex in swallowing was similar to that in tongue movement, except for earlier activation in swallowing. Postmovement processing of swallowing was lesser than that of tongue movement in face/tongue SMI; probably suggesting that the cerebral cortex does not play a significant role in postmovement processing of swallowing. SMA plays a supplementary role to face/tongue SMI both in swallowing and tongue movements.

Adult↗
PubMed2001

Cerebral cortical representation of reflexive and volitional swallowing in humans.

The purpose of this study was to compare cerebral cortical representation of experimentally induced reflexive swallow with that of volitional swallow. Eight asymptomatic adults (24-27 yr) were studied by a single-trial functional magnetic resonance imaging technique. Reflexive swallowing showed bilateral activity concentrated to the primary sensory/motor regions. Volitional swallowing was represented bilaterally in the insula, prefrontal, cingulate, and parietooccipital regions in addition to the primary sensory/motor cortex. Intrasubject comparison showed that the total volume of activity during volitional swallowing was significantly larger than that activated during reflexive swallows in either hemisphere (P < 0.001). For volitional swallowing, the primary sensory/motor region contained the largest and the insular region the smallest volumes of activation in both hemispheres, and the total activated volume in the right hemisphere was significantly larger compared with the left (P < 0.05). Intersubject comparison showed significant variability in the volume of activity in each of the four volitional swallowing cortical regions. We conclude that reflexive swallow is represented in the primary sensory/motor cortex and that volitional swallow is represented in multiple regions, including the primary sensory/motor cortex, insular, prefrontal/cingulate gyrus, and cuneus and precuneus region. Non-sensory/motor regions activated during volitional swallow may represent swallow-related intent and planning and possibly urge.

Adult↗
PubMed1991

Coordination of swallowing and respiration in unconscious subjects.

We investigated the coordination of swallowing and breathing in 11 unconscious patients with an endotracheal tube in place during the recovery period from general anesthesia. Swallows occurred during both the inspiratory and expiratory phases with no preponderant occurrence during either phase. When a swallow occurred during inspiration, the inspiration was interrupted immediately and was followed by expiration, but the durations of both inspiration and expiration were progressively increased as the time from the onset of inspiration to the onset of swallowing was progressively delayed. A swallow coinciding with the expiratory phase progressively prolonged the duration of the expiration that had been interrupted as the timing of swallowing was progressively delayed. Repeated swallows invariably and in a predictable manner caused changes in the breathing pattern. Thus when the frequency of regularly repeated swallows was relatively high, the breathing pattern was characterized by regular, shallow, and rapid breaths. When the frequency of regularly repeated swallows was relatively low, the breathing pattern was characterized by regular, deep, and slow breaths. When the frequency of repeated swallows was irregular, the breathing patterns were characterized by inconsistent changes in tidal volume and respiratory frequency. Our results indicate that, in unconscious subjects, some mechanisms integrating respiration and swallowing are operative and responsible for changes in breathing patterns during swallowing.

Adult↗
PubMed1991

Videoendoscopic evaluation of patients with dysphagia: an adjunct to the modified barium swallow.

The modified barium swallow is currently the most comprehensive, widely available, and easily interpreted technique for the evaluation of patients with dysphagia by the head and neck surgeon. However, it requires the facilities, personnel, and use of a radiology suite, a trained speech pathologist, and exposure of the patient to radiation. It would therefore be helpful to have an adjunctive, physician based, nonradiographic method of examination that could provide information similar to and possibly even more complete than that supplied by the modified barium swallow. Such an adjunctive method could help otolaryngologist-head and neck surgeons confronted by a new patient with swallowing difficulties to orient themselves to the nature and severity of the problem while waiting for the modified barium swallow to be scheduled, performed, and reviewed. It could also be a helpful tool for management of patients with cancer of the head and neck, whose swallowing function may change rapidly in the early postoperative period. In such cases, intervals between modified barium swallow examinations (dictated by concern over radiation exposure) may be too far apart to allow up-to-the-minute decisions on case management. Finally, some patients who may be too ill to travel to the radiology suite might benefit from a bedside procedure that would yield information about swallowing function similar to that provided by the modified barium swallow. Videoendoscopic evaluation of dysphagia (VEED) is a protocol I developed and have used regularly since 1984. Experience with this method of dysphagia evaluation has shown that it answers the needs outlined above. Its usefulness also goes beyond that of the modified barium swallow by providing a more detailed understanding of the component anatomic and functional deficits that comprise a given patient's swallowing problem, information about upper aerodigestive tract sensory deficits, and a means for visual feedback training of pharyngeal and laryngeal musculature. The protocol is reviewed here. Case reports illustrating the clinical usefulness of VEED as an adjunct to the modified barium swallow are also presented, and the relative strengths and weaknesses of VEED and the modified barium swallow are compared.

Aged↗
PubMed2004

Contribution of eye retraction to swallowing performance in the northern leopard frog, Rana pipiens.

Most anurans retract and close their eyes repeatedly during swallowing. Eye retraction may aid swallowing by helping to push food back toward the esophagus, but this hypothesis has never been tested. We used behavioral observations, cineradiography, electromyography and nerve transection experiments to evaluate the contribution of eye retraction to swallowing in the northern leopard frog, Rana pipiens. Behavioral observations of frogs feeding on 1.5 cm long crickets reveal a high degree of variability in eye retraction and swallowing. Eye retraction can occur bilaterally or unilaterally, and both swallowing movements and eye retraction can occur separately as well as together. During swallowing, cineradiography shows that the eyes and associated musculature retract well into the oropharynx and appear to make contact with the prey item. This contact appears to help push the prey toward the esophagus, and it may also serve to anchor the prey for tongue-based transport. Electromyographic recordings confirm strong activity in the retractor bulbi muscles during eye retraction. After bilateral denervation of the retractor bulbi, frogs maintain the ability to swallow but show a 74% increase in the number of swallows required per cricket (from a mean of 2.3 swallows to a mean of 4.0 swallows per cricket). Our results indicate that, in Rana pipiens feeding on medium-sized crickets, eye retraction is an accessory swallowing mechanism that assists the primary tongue-based swallowing mechanism.

Analysis of Variance↗
PubMed2002

Cortical representation of swallowing: a modified dual task paradigm.

It is unclear whether the cortical representation of swallowing is lateralized to the left cerebral hemisphere, right hemisphere, or bilaterally represented. As dysphagia is common in acute stroke, it is important to elucidate swallowing lateralization to facilitate earlier detection of stroke patients who may be at greater risk for dysphagia and aspiration. In this study, a modified dual task paradigm was designed to study laterality of swallowing in a group of 14 healthy, young, right-handed, male adults. The subjects were studied at baseline and with interference. Baseline conditions, performed separately, were continuous swallowing, finger tapping using the right and left index fingers, and word repetition. Interference tasks, including tapping with the right index finger, tapping with the left index finger, and word repetition, were completed with and without swallowing. Finger-tapping rate was measured, and x-ray samples of the swallowing task were taped to measure swallowing rate and volume swallowed. At baseline, the rate of tapping the right index finger was significantly faster than that of the left index finger. There was a significant decline in the tapping rates of both left and right index fingers with swallowing interference. The volume per swallow was significantly reduced during the interfering language task of silent repetition. These results offer partial support for a bilateral representation of swallowing as well as suggest an important left hemispheric contribution to swallowing. However, it cannot be concluded that the left hemisphere is more important than the right, as a comparable right hemisphere task was not studied.

Adult↗
PubMed2005

[The management of swallowing disorders through rehabilitation methods].

OBJECTIVES: Swallowing disorders are commonly encountered in ENT practice, and dysphagia may present a challenge with respect to diagnosis and management. This study aimed to examine patients with swallowing disorders. PATIENTS AND METHODS: The study included 280 patients (153 males, 127 females; mean age 53 years; range 3-98 years) who presented with complaints of swallowing difficulties between October 2000 and June 2002. The patients were examined according to the protocol of our department for swallowing disorders, which involved a detailed history taking, a patient questionnaire on swallowing disorders, cervical auscultation, and modified barium swallow studies. When further investigation was needed, fiber-optic endoscopic swallow studies, ultrasonic evaluation of the tongue base, neck CT, and 24-hour double-probe pH monitoring were also undertaken. RESULTS: A diagnosis of a swallowing disorder (premature spills, pulling in the vallecula and/or pyriform sinuses, penetration and/or aspiration, and delayed swallow reflex) was made in 164 patients. Dysphagia arose from a mechanical cause in 55%, and from a neurological cause in 32%. A multiphase rehabilitation program was initiated, which included positioning, adjusting bolus consistency, oral-motor range of motion exercises, use of palatal devices and swallowing techniques. Rehabilitation resulted in normal swallowing in 128 patients (78%). CONCLUSION: Mechanical causes should also be sought in patients with swallowing disorders.

Adolescent↗
PubMed2005

Regional variation and relationships between the contaminants dde and selenium and stable isotopes in swallows nesting along the Rio Grande and one reference site, Texas, USA.

Cave swallows (Petrochelidon fulva) and cliff swallows (P. pyrrhonota) nest in numerous colonies throughout the Texas portion of the Rio Grande along the U.S. border with Mexico. We collected swallows during 1999 and 2000 from eight locations along the Rio Grande to determine if delta15N and delta13C values could be used to predict 1,1-di-(p-chlorophenyl-)2,2-dichloroethene (DDE) and selenium (Se) contaminant burdens in insectivorous birds nesting across a geographic gradient in the Texas-Mexico border and to discern if stable isotopes could help discriminate between local versus nonlocal acquisition of contaminants. We analysed delta15N and delta13C in liver and muscle and DDE and Se in swallow carcasses. Within individuals, delta15N was higher in liver than in muscle of both species by an average of 1.34%, whereas delta13C was 0.145% higher in muscle than in liver. Significant differences occurred among locations in delta15N and delta13C values in liver and muscle of both species. Cave swallows from three locations in the Lower Rio Grande Valley were more enriched in delta15N than swallows from other sites. In general, swallows nesting in more northern latitudes along the Rio Grande had lower delta15N and delta13C values than those nesting farther south. Concentrations of DDE were significantly greater in swallows from El Paso, Llano Grande, and Pharr than in those from Brownsville, Falcon Lake, Laredo, Del Rio, and a reference site outside the Rio Grande. All swallows (n = 21) from El Paso, Llano Grande, and Pharr had DDE concentrations > or = 3 microg g(-1) wet weight (ww), a value three times greater than the estimated threshold in avian prey that could cause potential reproductive failures in raptors. Concentrations of Se also were significantly greater in El Paso and Del Rio than at other locations. Most Se concentrations were not of concern for direct effects on birds or their predators. Principal component analysis indicated some positive correlations between delta15N and delta13C values in tissues and contaminant concentrations in carcass; however, analysis of covariance suggested a stronger effect of location on concentrations of DDE and Se. At the local level (Llano Grande and Pharr) there was a significant positive correlation between delta15N in liver and DDE concentrations in swallow carcasses; however, Se concentrations were not significantly correlated with isotopes even at the local level. Our results provide a good database of delta15N and delta13C values for insectivorous birds nesting along the Rio Grande. Similar ecologies for cave and cliff swallows and their abundance and wide distribution along the Rio Grande make them ideal indicators of environmental pollution of this portion of the Texas-Mexico border.

Animals↗
PubMed1985

Identification of the medullary swallowing regions in the rat.

The aim of the present study was to identify the central structures involved in the organization of the swallowing reflex in the rat. Using concentric bipolar electrodes, the medulla and pons were systematically explored in order to determine which central areas responded to stimulation by inducing swallowing. These areas, which were located in the dorsal medulla oblongata, were the solitary tract, the nucleus of the solitary tract (NST) and the adjacent reticular formation. Stimulation of the ventral ponto-medullary regions was ineffective with regard to the initiation of the swallowing reflex. The activity of medullary swallowing neurons was recorded using extracellular microelectrodes. These swallowing neurons responded with a burst of spikes (swallowing activity) which was closely linked to the swallowing reflex elicited by stimulation of the superior laryngeal nerve (SLN). Under SLN stimulation, the activity of some of the swallowing neurons furthermore showed an initial response consisting of 1 or 2 spikes after a brief latency. According to their location and the latency of their initial response, swallowing neurons were divided into two groups. Group I neurons were located in a dorsal area of the medulla oblongata corresponding to the NST and the adjacent reticular formation. All these neurons exhibited an initial response with a very short latency (1 to 4 ms), the swallowing activity of most of these neurons started before the onset of the swallowing motor sequence. Group II neurons were located either in a ventral area corresponding to the nucleus ambiguus and the surrounding reticular formation or in a dorsal and medial area corresponding to the hypoglossal nucleus and its vicinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗