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PubMed2005

Tongue pressure against hard palate during swallowing in post-stroke patients.

OBJECTIVES: The tongue plays an important role in swallowing by contacting the palate. The aim of the present study was to investigate the characteristics of tongue pressure production during swallowing in post-stroke patients using a newly developed sensor sheet. MATERIALS AND METHODS: Ten post-stroke inpatients with hemiplegia and five healthy volunteers participated in this study. Magnitude of tongue pressure during a dry swallow was measured using a newly developed sensor sheet comprising five sensors applied directly to the palate or to the palatal surface of a maxillary denture using denture adhesive. Swallowing ability was evaluated by measuring the time taken to swallow 30 ml of water. The magnitude of tongue pressure was compared between the post-stroke patients and healthy subjects as well as between each measuring point in both groups. The relationship between tongue pressure and swallowing ability and that between tongue pressure and state of occlusal support were also examined. RESULTS: The magnitude of tongue pressure in the post-stroke patients was smaller than that of the healthy subjects at the measuring points along the median line (Welch test, p < 0.05), larger in the non-paralysed side than in the paralysed side (two-way ANOVA, p < 0.05), and was influenced by swallowing ability and occlusal support (Welch test, p < 0.05). CONCLUSIONS: Measurement of the magnitude of tongue pressure shows promise as a simple, non-invasive and quantitative method by which tongue activity in post-stroke patients, in whom swallowing ability is a concern, could be evaluated.

Adult↗
PubMed2002

An arterially perfused decerebrate preparation of Suncus murinus (house musk shrew) for the study of emesis and swallowing.

Arterially perfused, decerebrate preparations of the insectivore, Suncus murinus were made to determine whether the emetic reflex could be activated in such a preparation using a range of stimuli shown to be emetic in conscious or anaesthetised Suncus. Efferent phrenic and vagus nerve activities and electromyograms (EMGs) from the temporalis, abdominal oesophagus and trapezius muscles were recorded, as well as longitudinal shortening of the oesophagus and dorso-ventral movements of the thorax. The preparations swallowed spontaneously every 0.6 to 6.5 min. The duration of a swallow was 3.1 +/- 0.3 s (recorded as the time taken for the oesophagus to shorten and recover to its resting position) and the oesophagus shortened by 3.5 +/- 0.4 mm during a swallow. The emetic reflex was activated by electrical stimulation (30 Hz, 10-20 V, 0.2 ms pulse width, for 30 s) of abdominal vagal afferents (latency < 30 s) or by arterial perfusion with either 40 nM of the capsaicin analogue resiniferatoxin (latency 1.7 +/- 0.6 min), 6 microM nicotine (latency 1.6 +/- 0.1 min) or 1 microM of the phosphodiesterase IV inhibitor CP-80,633 (latency 8.9 +/- 3.9 min). These emetic stimuli produced somatic and visceral movements in Suncus preparations indicative of activation of the emetic reflex. There were pronounced contractions of the thorax that occurred simultaneously with oesophageal shortening and mouth opening, separated by thorax expansion and a burst of phrenic nerve activity. During emetic-like episodes, oesophageal shortenings were only 0.84 +/- 0.1 s in duration, faster than the duration of shortening observed during swallowing (cf. swallowing, 3.1 +/- 0.3 s; P < 0.0001). The shortening of the oesophagus during emetic-like episodes was 6.2 +/- 0.4 mm, which was greater than the shortening seen during swallowing (cf. swallowing, 3.5 +/- 0.4 mm; P < 0.0001). We conclude that the emetic reflex can be activated in our Suncus preparations and that this non-sentient small adult animal model can now be used to study the neurophysiology and pharmacology of swallowing and emesis.

Animals↗
PubMed2003

Differential changes in human pharyngoesophageal motor excitability induced by swallowing, pharyngeal stimulation, and anesthesia.

We investigated the effects of water swallowing, pharyngeal stimulation, and oropharyngeal anesthesia on corticobulbar and craniobulbar projections to human swallowing musculature. Changes in pathway excitability were measured via electromyography from swallowed intraluminal pharyngeal and esophageal electrodes to motor cerebral and trigeminal nerve magnetic stimulation. After both water swallowing and pharyngeal stimulation, pharyngoesophageal corticobulbar excitability increased (swallowing: pharynx = 59 +/- 12%, P < 0.001; esophagus = 45 +/- 20%, P < 0.05; pharyngeal stimulation: pharynx = 76 +/- 19%, P < 0.001; esophagus = 45 +/- 23%, P = 0.05), being early with swallowing but late with stimulation. By comparison, craniobulbar excitability increased early after swallowing but remained unaffected by pharyngeal stimulation. After anesthesia, both corticobulbar (pharynx =-24 +/- 10%, P < 0.05; esophagus = -28 +/- 7%, P < 0.01) and craniobulbar excitability showed a late decrease. Thus swallowing induces transient early facilitation of corticobulbar and craniobulbar projections, whereas electrical stimulation promotes delayed facilitation mainly in cortex. With removal of input, both corticobulbar and craniobulbar projections show delayed inhibition, implying a reduction in motoneuron and/or cortical activity.

Adult↗
PubMed1981

Human esophageal response to rapid swallowing: muscle refractory period or neural inhibition?

The peristaltic response of the normal human esophagus to 10 repeated water swallows separated by varying time intervals (5, 10, 15, 20, and 30 s) between swallows was studied. Pressures measured during the shorter time intervals were of lower amplitude than those at 30-s swallowing intervals throughout the esophagus, with the distal esophagus showing the greatest effect. Frequency of peristalsis was decreased throughout the esophagus with rapid swallowing, especially distally at the 5- and 10-s time intervals. There was no significant change in wave velocity or duration at these time intervals. These data suggest that there is a refractory period in the distal (smooth muscle) esophagus. A series of paired swallows separated by 5 s resulted in a significant decrease in amplitude of the first swallow, and this was more marked in the distal esophagus. These data indicate that there is an inhibition of the progression of peristalsis by a subsequent swallow, probably through a neural mechanism. These studies show that repeated liquid swallows may effect peristalsis by two mechanisms: refractoriness of esophageal smooth muscle and a neural inhibitory discharge.

Adult↗
PubMed2001

Swallow-related cerebral cortical activity maps are not specific to deglutition.

Cortical representation of swallow-related motor tasks has not been systematically investigated. In this study, we elucidated and compared these cortical representations to those of volitional swallow using block-trial and single-trial methods. Fourteen volunteers were studied by functional magnetic resonance imaging. Cortical activation during both swallowing and swallow-related motor tasks that can be performed independent of swallowing, such as jaw clenching, lip pursing, and tongue rolling, was found in four general areas: the anterior cingulate, motor/premotor cortex, insula, and occipital/parietal region corresponding to Brodmann's areas 7, 19, and 31. Regions of activity, volume of activated voxels, and increases in signal intensity were found to be similar between volitional swallow and swallow-related motor tasks. These findings, using both block-trial and single-trial techniques, suggest that cerebral cortical regions activated during swallowing may not be specific to deglutitive function.

Adult↗
PubMed1990

Fetal swallowing: correlation of electromyography and esophageal fluid flow.

Patterns of fetal drinking behavior were quantified in five singleton fetuses (128 +/- 1 days gestation) by computer analysis of laryngeal-esophageal electromyography (EMG) and thoracic esophageal fluid flow. Esophageal flow was noted to be bidirectional with an average antegrade flow-to-retrograde flow ratio of 4.4 +/- 1.5. Retrograde esophageal flow coincided with diaphragmatic contractions, suggesting that inspiratory gastroesophageal pressure gradients may be operative. The regurgitated fluid was returned to the fetal rumen by thoracic esophageal contractions. Significant net fluid intake was noted during periods of primarily unidirectional antegrade esophageal flow. Fetuses swallowed an average of 35 +/- 9 ml/h during the 12-h study, extrapolating to an average daily volume of 840 +/- 224 ml. An EMG "propagated swallow" representing coordinated contractions of the thyrohyoid, nuchal esophagus, and thoracic esophagus averaged 43 +/- 3 swallows/h and was highly correlated with net esophageal flow. Nearly 60% of the total fluid intake occurred during "bouts" of propagated swallows, which represented only 8% of the study period. Bouts averaged 11.7 +/- 0.4 propagated swallows, lasted 2.1 +/- 0.2 min, and occurred every 27.6 +/- 1.7 min. Although EMG swallowing activity was similar, there were significant differences among fetuses in net esophageal fluid flow and volume per propagated swallow. We speculate that fetal fluid intake is dependent on the availability and physical properties of the swallowed fluid, whereas swallowing activity is primarily related to cortical maturation and thirst stimulation.

Animals↗
PubMed1998

Dopamine D1 receptor antagonist inhibits swallowing reflex in guinea pigs.

To determine whether dopamine D1 receptor antagonist impairs the swallowing reflex and reduces substance P (SP) in the peripheral organs, the swallowing reflex in terms of the number of swallows elicited by injections of three different volumes (0.2, 0.4, and 0.6 ml) of distilled water into the pharynx through a catheter was examined in anesthetized guinea pigs pretreated with Sch-23390. Animals were pretreated with either subcutaneous Sch-23390 (200 micrograms/kg) or a vehicle of Sch-23390 every 12 h for 7 days. The number of swallows was counted by submental electromyographic activity and visual observation of characteristic laryngeal movement. Injections of distilled water caused a volume-dependent increase in the number of swallows in animals without Sch-23390 treatment. Sch-23390 significantly decreased and exogenously administered SP increased the number of swallows elicited by all volumes of distilled water. FK-888 (10(-5) M, 1 ml), a specific inhibitor of the NK1 receptor, reduced the number of swallows to a greater degree than Sch-23390. Sch-23390 significantly reduced SP content in the laryngeal and pharyngeal mucosa compared with control. These results suggest that inhibition of the dopamine D1 receptor may impair the swallowing reflex and reduce SP content in the peripheral organs.

Animals↗
PubMed1990

Coordination of breathing, sucking, and swallowing during bottle feedings in human infants.

Incoordination of sucking, swallowing, and breathing might lead to the decreased ventilation that accompanies bottle feeding in infants, but the precise temporal relationship between these events has not been established. Therefore, we studied the coordination of sucks, swallows, and breaths in healthy infants (8 full-term and 5 preterm). Respiratory movements and airflow were recorded as were sucks and swallows (intraoral and intrapharyngeal pressure). Sucks did not interrupt breathing or decrease minute ventilation during nonnutritive sucking. Minute ventilation during bottle feedings was inversely related to swallow frequency, with elimination of ventilation as the swallowing frequency approached 1.4/s. Swallows were associated with a 600-ms period of decreased respiratory initiation and with a period of airway closure lasting 530 +/- 9.8 (SE) ms. Occasional periods of prolonged airway closure were observed in all infants during feedings. Respiratory efforts during airway closure (obstructed breaths) were common. The present findings indicate that the decreased ventilation observed during bottle feedings is primarily a consequence of airway closure associated with the act of swallowing, whereas the decreased ventilatory efforts result from respiratory inhibition during swallows.

Bottle Feeding↗
PubMed1984

Brainstem organization of the swallowing network.

Swallowing is a complex motor sequence involving the coordinated contraction of several muscles in the mouth, pharynx, larynx and esophagus. The motor sequence of swallowing, which can be entirely performed without afferent feedback, is centrally programmed by a neuronal network. This network can be divided into three levels: an afferent level corresponding to the input arm to the network, that is mainly the solitary tract; an efferent level corresponding to the output arm of the network, that is the different pools of motoneurons involved in swallowing and localized within the trigeminal and hypoglossal nuclei and the nucleus ambiguus; an organizing level corresponding to the interneuronal network which programs the swallowing motor sequence. The 'swallowing interneurons' of the organizing level are localized in two medullary regions: a dorsal region including the nucleus of the solitary tract (NST) and the adjacent reticular formation, and a ventral region corresponding to the lateral reticular formation above the nucleus ambiguus. Neurons localized within the NST region are interneurons which largely go to make up the part of the network which initiates and programs swallowing. Originating from these neurons, the central swallowing command is relayed by the interneurons within the ventrolateral reticular formation before reaching the different groups of motoneurons which excite the swallowing reactions.

Animals↗
PubMed2001

Dysphagia in lateral medullary infarction (Wallenberg's syndrome): an acute disconnection syndrome in premotor neurons related to swallowing activity?

BACKGROUND AND PURPOSE: We have investigated the pathophysiological mechanisms of dysphagia in Wallenberg's syndrome (WS) that are due to lateral medullary infarction (LMI). METHODS: Twenty patients with WS were evaluated by means of clinical and electrophysiological methods that measured the oropharyngeal phase of voluntarily initiated swallowing. For comparison, 22 patients with unilateral hemispheric infarction were investigated during the acute stage of stroke, and 4 patients with unilateral peripheral 9th and 10th cranial nerve palsies were studied. Age-matched 30 healthy control subjects were also included in the study. RESULTS: It was found that dysphagia was clinically more severe in WS patients than in the patients in the other groups. The pharyngeal phase of swallowing was predominantly impaired, whereas in patients with hemispheric stroke, dysphagia was related only to the delay of triggering of the voluntarily induced swallowing. In WS patients, the swallowing reflex was extremely slow in spite of the unilateral involvement due to LMI, whereas the pharyngeal phase of reflex swallowing remained within normal limits in patients with unilateral hemispheric stroke and patients with unilateral peripheral 9th and 10th cranial nerve palsies. CONCLUSIONS: Although in WS the lesion due to LMI is unilateral, its effect on oropharyngeal swallowing is bilateral. In LMI, primarily the premotor neurons in the nucleus ambiguous and their connections seem to be affected. Consequently, a disruption and/or disconnection of their linkage to swallowing-related cranial motor neuron pools bilaterally and to the contralateral nucleus ambiguous could produce the swallowing disorders in WS. However, the remaining intact ipsilateral premotor neurons and the contralateral center in the medulla oblongata may eventually begin to operate and overcome the severity and long-term persistence of dysphagia.

Adult↗
PubMed2002

Phasic vagal influence on the rate and timing of reflex swallowing.

We investigated the effects of sudden changes in ventilation induced by voluntary hyperpnea and breath-holding on repetitive reflex swallowing elicited by continuous infusion of distilled water into the pharynx in 13 healthy subjects. Ventilation was monitored using a pneumotachograph, and swallowing was identified by submental electromyography with interruption of airflow. We found that voluntary hyperpnea decreased the swallowing frequency whether end-tidal CO(2) tension was maintained at normocapnia or allowed to be hypocapnic. Also, the frequency of swallowing immediately increased with the start of breath-holding, but there was a sudden decrease in swallowing frequency during the hyperpnea observed immediately after the resumption of ventilation (post-breath-holding hyperpnea). The preponderant coupling of swallows with the expiratory phase was lost during voluntary hyperpnea but was maintained during post-breath-holding hyperpnea. These observations may suggest that vagally mediated reflexes are operative in normal physiologic situations and play an important role in the control of swallowing rate as well as in the timing of swallowing in reference to the respiratory cycle.

Adult↗
PubMed1996

Effects of two breath-holding maneuvers on oropharyngeal swallow.

This study quantified the effects of the supraglottic maneuver (SGM) and super supraglottic maneuver (SSGM) on laryngeal and pharyngeal movements before and during swallow. Simultaneous videofluoroscopic and videoendoscopic examinations of oropharyngeal swallowing were performed in eight healthy volunteers with and without maneuvers. Data analysis compared 1) temporal relationships of oropharyngeal events, 2) airway conditions at the time of selected oropharyngeal events, and 3) biomechanical computer analysis of swallowing events. Using these maneuvers, normal subjects produced earlier cricopharyngeal opening, prolonged pharyngeal swallow, some degree of laryngeal valving before swallow, and change in extent of vertical laryngeal position before swallow. These changes are more successful and maintained longer with the SSGM than the SGM. We concluded that breath-holding maneuvers alter not only airway conditions before swallow but also both the temporal relationships and biomechanical events during oropharyngeal swallow.

Adult↗
PubMed1998

FEESST: a new bedside endoscopic test of the motor and sensory components of swallowing.

We here introduce an office or bedside method of evaluating both the motor and sensory components of swallowing, called fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST). FEESST combines the established endoscopic evaluation of swallowing with a technique that determines laryngopharyngeal (LP) sensory discrimination thresholds by endoscopically delivering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve. Endoscopic assessment of LP sensory capacity followed by endoscopic visualization of deglutition was prospectively performed 148 times on 133 patients with dysphagia over an 8-month period. The patients had a variety of underlying diagnoses, with stroke and chronic neurologic disease predominating (n = 94). Subsequent to LP sensory testing, a complete dysphagia evaluation was conducted. Various food and liquid consistencies were dyed green, and attention was paid to their management throughout the pharyngeal stage of swallowing. Evidence of latent swallow initiation, pharyngeal pooling and/or residue, laryngeal penetration, laryngeal aspiration, and/or reflux was noted. Recommendations for therapeutic intervention were based on information obtained during the FEESST and often involved the employment of compensatory swallowing strategies, modification of the diet or its presentation, placement on non-oral feeding status, and/or referral to other related specialists. All patients successfully completed the examination. In 111 of the evaluations (75%), severe (>6.0 mm Hg air pulse pressure [APP]) unilateral or bilateral LP sensory deficits were found. With puree consistencies, 31% of evaluations with severe deficits, compared to 5% of evaluations with either normal sensitivity or moderate (4.0 to 6.0 mm Hg APP) LP sensory deficits, displayed aspiration (p < .001, chi2 test). With puree consistencies, 69% of evaluations with severe deficits, compared to 24% with normal or moderate deficits, displayed laryngeal penetration (p < .001, chi2 test). FEESST allows the clinician to obtain a comprehensive bedside assessment of swallowing that is performed as the initial swallowing evaluation for the patient with dysphagia.

Adult↗
PubMed1992

Effects of pollution on swallowing: how little we know.

Swallowing is an essential function of the upper alimentary tract. It is highly complex, requiring precise coordination of numerous nerves and muscles of the oral cavity, pharynx, larynx, and esophagus. Swallowing is integrated with other physiologic functions, including mastication and respiration. Impairments of swallowing may result from many different structural or physiologic disorders. Little is currently known about the direct effects of pollution on swallowing. Structures critical to swallowing, however, are vulnerable to damage by environmental hazards such as exposure to ionizing radiation or intake of toxins by ingestion or inhalation. The relationship of swallowing to environmental lung disease is an area of particular interest because impaired swallowing may result in aspiration of food particles into the lung, and because pollutants may hamper airway defense mechanisms. In this article, we discuss the possible impact of selected environmental agents on swallowing and suggest future directions for research.

Deglutition↗
PubMed2005

The effect of bilateral lingual nerve anesthesia and increased occlusal vertical dimension on the onset of swallowing in adult males.

The present study attempts to determine whether the onset of swallowing is affected by bilateral lingual and inferior alveolar nerve anesthesia and by raising the occlusal vertical dimension by wearing an occlusal bite plate. Twenty young male volunteers were selected and asked to chew and swallow corned beef and a corned beef and liquid mixture in their usual manner before and after modifications were made. Oral and pharyngeal swallowing was investigated using videofluoroscopic examination in the lateral plane. Eight objective indicators, including oral containment time, swallowing threshold, and pharynx-to-swallow intervals were estimated. Oral containment time, total sequence duration, total number of chews, and total number of swallows of the two test foods were significantly different before and after the modifications. Individual pharynx-to-swallow intervals also varied. The results indicate that modification of the masticatory condition affects the onset of swallowing and that changes in the onset varied among the participants.

Adult↗
PubMed1994

Recovery of the swallowing reflex after propofol anesthesia.

The swallowing reflex is depressed by anesthetics. During recovery from anesthesia the rapid return of laryngeal and upper airway reflexes is important to protect the lower airway from aspiration. This study measures the recovery of the swallowing reflex after propofol anesthesia. Fifteen patients undergoing a colonoscopy under general anesthesia were studied. No premedication was given. Anesthesia was induced with propofol 2 mg/kg followed by an infusion of 10 mg.kg-1.h-1. The swallowing reflex was measured every 3 min after the end of propofol infusion for 30 min. To initiate swallowing, 0.3 mL of distilled water was injected into the pharynx at two different speeds: a slow injection over 3 s, and a bolus injection. The swallowing reflex was determined by measuring the latency period (i.e., time from water injection to start of electromyographic (EMG) activity measured in the glossal muscles). Swallowing activity was determined by integration of the EMG (EMGi) of the glossal muscles during swallowing. The latency periods after slow and bolus injections were significantly increased for the first 12 min after the end of the propofol infusion and returned to control (preanesthetic values) at 24 min. The EMGi was significantly decreased over the first 12 min and returned to control at 21 min. Propofol depresses the swallowing reflex, but complete recovery is rapid. This study suggests that the oral intake could be allowed early after recovery from anesthesia when propofol is used as the sole anesthetic.

Adult↗
PubMed2004

Sequential swallows have no influence on esophageal contractions of patients with iron deficiency anemia.

BACKGROUND: An experimental study showed that thyropharyngeal, cricopharyngeal and cervical esophageal muscles of rabbits with iron deficiency anemia had morphological changes similar to those observed in muscular dystrophy, causing myastenic changes in muscles involved in swallowing. Our hypothesis is that patients with iron deficiency anemia may have a decrease in esophageal contractions with successive swallows. PATIENTS AND METHOD: We studied the esophageal motility of 12 women with iron deficiency anemia aged 31 to 50 years (median 36 years) with serum iron from 11 to 40 mug/dL (median 21 mug/dL), and 13 asymptomatic women aged 26 to 49 years (median 35 years) with serum iron over 60 mug/dL. We used the manometric method with continuous perfusion. The esophageal contractions were measured at 3, 9 and 15 cm from the upper margin of a sleeve that straddled the lower esophageal sphincter. Each subject performed 10 swallows of a 2 mL bolus of water alternated with 10 swallows of a 7 mL bolus, with an interval of 30 seconds between swallows. We measured the amplitude, duration, velocity and area under the curve of contractions. RESULTS: There was no difference between the swallows of a 2 mL or 7 mL bolus. The amplitude, duration and area under the curve were lower in patients with iron deficiency than in asymptomatic volunteers, mainly in the proximal and middle esophageal body. There was no difference in velocity. Sequential swallows did not change contraction amplitude, duration, velocity or area under curve in patients and volunteers. CONCLUSION: Although the power of esophageal contractions was decreased in patients with iron deficiency anemia, sequential swallows did not cause further impairment.

Adult↗
PubMedDate not supplied

Clinical and cognitive predictors of swallowing recovery in stroke.

This retrospective study determined whether specific neurological features were associated with initial and final swallowing outcomes in acute stroke patients. A chart review of 65 acute stroke patients suggested that certain clinical and neurocognitive behaviors were associated with swallowing outcomes. Hemispatial neglect was significantly associated with initial nonoral dietary intake, whereas aphasia was not associated with swallowing outcome. Results from the initial clinical swallowing evaluations suggested that the presence of at least four of six clinical features (cough after swallow, voice change after swallow, abnormal volitional cough, abnormal gag reflex, dysphonia, and dysarthria) were associated with poor initial and final swallowing outcomes. Whether specific lesion location, size, or a combination of clinical neurological deficits are associated with poor initial and final swallowing outcomes is unclear. Prospective studies are warranted for further investigation of these relationships.

Adult↗