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PubMedDate not supplied

Swallow recovery in an oral cancer patient following surgery, radiotherapy, and hyperthermia.

BACKGROUND: No study has examined the nature and extent of swallowing impairment in oral cancer patients following treatment with combined hyperthermia and interstitial radiotherapy. Few studies have examined the effects of voluntary swallow maneuvers (supersupraglottic and Mendelsohn) on pharyngeal phase swallowing in the oral cancer patient treated with surgery or radiotherapy. This study examined the effects of combined radiotherapeutic salvage treatments of hyperthermia and interstitial implantation and swallow recovery using swallow maneuvers in a surgically treated and irradiated oral cancer patient. METHODS: The patient under study, a 51-year-old man, underwent radiotherapy, according to Radiation Therapy Oncology Group (RTOG) protocol #8419, consisting of a combination of interstitial irradiation and hyperthermia to the base of tongue, for a recurrent squamous cell cancer. He underwent videofluorographic (VFG) examination of his swallowing, a modified barium swallow at three time points: 2 days following radiotherapy treatment (VFG1), 4 weeks later (VFG2), and 8 months later (VFG3). Temporal and biomechanical analyses of swallows were performed at each time point. RESULTS: Swallow maneuvers and time resulted in improved laryngeal elevation and laryngeal vestibule closure during the swallows on VFG2. Maximum upper esophageal sphincter (UES) opening width and duration were more normal. Fewer swallows were required for bolus clearance through the pharynx. Base of tongue tissue necrosis occurred as a complication of radiotherapy between VFG2 and VFG3, with resultant severe reduction in posterior movement of the tongue base, incomplete tongue base contact to the posterior pharyngeal wall, reduced laryngeal elevation, and incomplete laryngeal vestibule closure during swallowing at VFG3. UES opening became less normal and a greater number of swallows were required for bolus clearance through the pharynx. CONCLUSIONS: Combined interstitial irradiation and hyperthermia can cause oropharyngeal swallowing problems. Time and swallow therapy can improve these swallow disorders. Tongue base tissue necrosis can cause further swallow impairment, emphasizing the importance of the tongue base in normal deglutition. Further studies are needed to examine the impact of combined hyperthermia and interstitial implantation for treatment of tongue base tumors on swallow functioning in a larger group of patients.

Brachytherapy↗
PubMed2004

Are 10 wet swallows an appropriate sample of esophageal motility? Yes and no.

BACKGROUND: Traditionally 10 wet swallows are used to assess esophageal motility. Given this relative small number of swallows concerns have been raised whether the abnormal findings based on 10 wet swallows would persist with another set of 10 wet swallows. PURPOSE: To evaluate whether 10 wet swallows during esophageal manometry is an adequate sampling of esophageal motility. METHODS: Over a 4-month-period 100 consecutive patients (excluding patients with achalasia) were given 20 liquid (5 ml each) swallows. The standard manometry technique in our laboratory was performed using 10 wet swallows with pressure transducers placed 4 cm and 9 cm above the lower esophageal sphincter (LES). The diagnosis was based on the initial 10 swallows. The additional 10 swallows were blinded and separately analyzed, then compared with the initial swallows for each patient. RESULTS: Of the 100 studies (64 women; mean age 51; range 21-85), 91 had a consistent diagnosis for both pairs of 10 swallows. The number of abnormal swallows (ineffective or simultaneous) differed between the 2 sets of 10 swallows in 9 patients, but, when the first 10 were analyzed vs. all 20 swallows only 2 patients had discordant diagnoses. There was an excellent agreement between the 1st and 2nd set of 10 swallows (kappa = 0.846) and between the first 10 and all 20 swallows (kappa = 0.965). CONCLUSIONS: Ten wet swallows are sufficient for making a manometric diagnosis, because additional swallows are likely to change the diagnosis in only 2% of patients.

Adult↗
PubMed1993

An investigation of the coupling between respiration, mastication, and swallowing in the awake rabbit.

1. The interrelationships between respiration, mastication, and swallowing were studied in awake rabbits previously prepared for the chronic recording of jaw movements and the electromyographic activity of jaw and throat muscles. These signals were recorded before, during, and after the mastication of rabbit chow, together with respiratory movements. 2. The onset of activity in the thyrohyoid muscle was used as a marker for swallowing. Measurements were made of cycle duration, and the phase relationship between the masticatory and respiratory rhythms was calculated. Deviations in masticatory and respiratory movements during swallowing were detected; the phases of the masticatory and respiratory cycles in which the deviations occurred were determined, and the intervals between the deviations and the swallowing marker were calculated. 3. Two characteristic swallowing patterns were observed that were called Interposed and Terminal swallows. Interposed swallows occurred within a masticatory sequence, while Terminal swallows ended the sequence. 4. In most rabbits, respiratory rate slowed during mastication. This brought the average frequency of the two movements closer together, and there was a weak but significant correlation between the masticatory and respiratory rates. However, respiration and mastication were not linked on a cycle-by-cycle basis, and the change in respiratory rate was found to be unrelated to masticatory rate. Further, there was no tendency for the masticatory and respiratory rhythms to adopt any particular phase relationship as swallowing was approached. Some weak and transient phase coupling of the two systems occurred after swallowing. 5. During swallowing, respiration was most often inhibited soon after the start of the inspiratory phase. Swallows within a masticatory sequence occurred most frequently during the early opening phase of the masticatory cycle, and swallows after the end of a sequence occurred with the jaw in the resting position. There was a strong tendency for the durations of the masticatory and respiratory cycles containing deviations to be longer than preceding control cycles, and the effect on respiration lasted several cycles. 6. For both Interposed and Terminal swallows, a tight temporal relationship was observed between deviations in respiration and the swallowing marker: most deviations tended to occur before swallowing. In contrast, the time of deviations in mastication relative to the swallowing marker depended on swallow type and was more variable. Finally, there was no link between the start of the pauses in the two rhythms. 7. We conclude that respiratory and masticatory processes are not strongly coupled.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1999

Features of cortically evoked swallowing in the awake primate (Macaca fascicularis).

Although the cerebral cortex has been implicated in the control of swallowing, the output organization of the cortical swallowing representation, and features of cortically evoked swallowing, remain unclear. The present study defined the output features of the primate "cortical swallowing representation" with intracortical microstimulation (ICMS) applied within the lateral sensorimotor cortex. In four hemispheres of two awake monkeys, microelectrode penetrations were made at </=1-mm intervals, initially within the face primary motor cortex (face-MI), and subsequently within the cortical regions immediately rostral, lateral, and caudal to MI. Two ICMS pulse trains [35-ms train, 0.2-ms pulses at 333 Hz, </=30 microA (short train stimulus, T/S); 3- to 4-s train, 0.2-ms pulses at 50 Hz, </=60 microA (continuous stimulus, C/S)] were applied at </=500-micron intervals along each microelectrode penetration to a depth of 8-10 mm, and electromyographic (EMG) activity was recorded simultaneously from various orofacial and laryngeal muscles. Evoked orofacial movements, including swallowing, were verified by EMG analysis, and T/S and C/S movement thresholds were determined. Effects of varying ICMS intensity on swallow-related EMG properties were examined by applying suprathreshold C/S at selected intracortical sites. EMG patterns of swallows evoked from various cortical regions were compared with those of natural swallows recorded as the monkeys swallowed liquid and solid material. Results indicated that swallowing was evoked by C/S at approximately 20% of 1,569 intracortical sites where ICMS elicited an orofacial motor response in both hemispheres of the two monkeys, typically at C/S intensities </=30 microA. In contrast, swallowing was not evoked by T/S in either monkey. Swallowing was evoked from four cortical regions: the ICMS-defined face-MI, the face primary somatosensory cortex (face-SI), the region lateral and anterior to face-MI corresponding to the cortical masticatory area (CMA), and an area >5 mm deep to the cortical surface corresponding to both the white matter underlying the CMA and the frontal operculum; EMG patterns of swallows elicited from these four cortical regions showed some statistically significant differences. Whereas swallowing ONLY was evoked at some sites, particularly within the deep cortical area, swallowing was more frequently evoked together with other orofacial responses including rhythmic jaw movements. Increasing ICMS intensity increased the magnitude, and decreased the latency, of the swallow-related EMG burst in the genioglossus muscle at some sites. These findings suggest that a number of distinct cortical foci may participate in the initiation and modulation of the swallowing synergy as well as in integrating the swallow within the masticatory sequence.

Animals↗
PubMed2001

Cerebral cortical representation of automatic and volitional swallowing in humans.

Although the cerebral cortex has been implicated in the control of swallowing, the functional organization of the human cortical swallowing representation has not been fully documented. Therefore, the present study determined the cortical representation of swallowing in fourteen healthy right-handed female subjects using single-event-related functional magnetic resonance imaging (fMRI). Subjects were scanned during three swallowing activation tasks: a naïve saliva swallow, a voluntary saliva swallow, and a water bolus swallow. Swallow-related laryngeal movement was recorded simultaneously from the output of a bellows positioned over the thyroid cartilage. Statistical maps were generated by computing the difference between the magnitude of the voxel time course during 1) a single swallowing trial and 2) the corresponding control period. Automatic and volitional swallowing produced activation within several common cortical regions, the most prominent and consistent being located within the lateral precentral gyrus, lateral postcentral gyrus, and right insula. Activation foci within the superior temporal gyrus, middle and inferior frontal gyri, and frontal operculum also were identified for all swallowing tasks. In contrast, activation of the caudal anterior cingulate cortex was significantly more likely in association with the voluntary saliva swallow and water bolus swallow than the naïve swallow. These findings support the view that, in addition to known brain stem areas, human swallowing is represented within a number of spatially and functionally distinct cortical loci which may participate differentially in the regulation of swallowing. Activation of the insula was significantly lateralized to the right hemisphere for the voluntary saliva swallow, suggesting a functional hemispheric dominance of the insula for the processing of swallowing.

Adult↗
PubMed1985

Effects of swallowing on the pattern of continuous respiration in human adults.

Swallowing must interact with respiration so that a swallow causes minimal or no disturbance of continual respiration. In order to study the coordinate control of swallowing and respiration, we investigated the effects of spontaneous and water-induced swallows on the pattern of ongoing respiration in 8 adult human subjects. Swallows were identified by submental electromyograms and visual observation of the characteristic laryngeal movements. Both spontaneous and water-induced swallows occurred during all phases of the respiratory cycle, but approximately 80% of swallows occurred during the expiratory phase. No essential difference between spontaneous and water-induced swallows in the effects of the swallowing on respiration was observed. A swallow coinciding with the expiratory phase prolonged the duration of the same expiration that had been interrupted, whereas a swallow coinciding with the inspiratory phase interrupted the inspiration immediately and was followed by a short expiratory duration. There was a positive correlation between the time from the onset of the expiration to the onset of the swallowing and the duration of the expiration interrupted by the swallowing, indicating that the later the onset of the swallowing takes place, the more is the expiration prolonged. The duration of respiratory cycle in the breaths immediately following the swallow was not affected by the swallow, but there was a considerable increase in the tidal volume of the postswallowing breaths. These results suggest that the changes in respiratory pattern induced by the act of swallowing may depend on some mechanism that regulates the coordination of respiration and swallowing.

Adult↗
PubMed1997

Exploration of pharyngeal swallowing by audiosignal recording.

The aims of this study were to analyze the following by audiorecording of swallows: (1) the influence on the volume and consistency of ingested substances on the audiosignal recorded during separate swallows; and (2) the characteristics of successive swallows during ingestion of 100 ml of the same substances to define deglutitive behaviors. Volunteers followed two protocols. Protocol (P) 1 comprised ingestion of 100 ml of water or yoghurt in successive swallows and Protocol 2 comprised separate swallows of different volumes of the same substances. Audiosignal recordings were made with a dynamic microphone. The following parameters were measured in P1: total time of ingestion (TT), number of swallows necessary for ingestion (N), and spontaneous swallowing intervals (SI). In P2 the duration (d) of each signal was measured according to consistency and volume. Mean (m) values were then calculated (TTm, Nm, SIm, and dm). During P1, TTm for yoghurt was significantly longer than for water (23.1 vs. 6.5 sec (men) and 21.8 vs. 7.8 sec (women). Nm was also greater for yoghurt (10.1 vs. 4.3 (men) and 10.0 vs. 4.8 (women). Three types of swallowing behavior were defined according to SI: swallowing at regular intervals (Reg) with increasing intervals during ingestion (Prog) and swallowing at variable intervals (Irreg). These patterns did not differ significantly according to sex. In P2 the increase in volume swallowed increased the duration (dm) of the signal for water (600 msec for 5 ml and 960 msec for 15 ml). The dm for yoghurt was significantly less than for water (580 msec for 5 ml and 920 msec for 15 ml). Our technique of recording sounds of pharyngeal swallowing is simple, reproducible, and not expensive. It permitted the analysis of each swallow according to volume and consistency and the determination of three swallowing patterns (Reg, Prog, and Irreg), taking into account the spontaneous swallowing interval. Ingestion by successive swallows could be used to characterize certain pharyngoesophageal motor dysfunctioning in relation to this reference population and to integrate this into a deglutition rehabilitation program.

Acoustics↗
PubMed2002

Effects of repeated wet and dry swallows in healthy adult females.

Understanding changes that may occur in the swallow with repetitive use in healthy individuals is a prerequisite to evaluate and treat persons with compromised swallowing. To determine any systematic effect of use on swallow function, we attempted to tax the swallow mechanism in a rigorous sequence of dry and liquid swallow conditions. Oropharyngeal temporal measures were assessed videofluoroscopically for 12 healthy females aged 20-29 during 42 wet and 5 dry swallows. No significant effects were found for any temporal measures over a series of 21 l-mL and 21 cup swallows plus 5 dry swallows, indicating swallow efficiency and safety do not appear to decline over 47 swallows in this young adult population. Additionally, no significant effects were found over the dry swallows or when 1-mL liquid swallows were compared with the dry, indicating dry swallows do not demonstrate significant change over a 5-swallow series due to reduced available saliva. Ability of subjects to perform consecutive dry swallows varied greatly. Results of this study provide normative data regarding multiple, consecutive, wet and dry swallowing in a healthy female population.

Adult↗
PubMed1999

Swallowing function after stroke: prognosis and prognostic factors at 6 months.

BACKGROUND AND PURPOSE: Swallowing dysfunction (dysphagia) is common and disabling after acute stroke, but its impact on long-term prognosis for potential complications and the recovery from swallowing dysfunction remain uncertain. We aimed to prospectively study the prognosis of swallowing function over the first 6 months after acute stroke and to identify the important independent clinical and videofluoroscopic prognostic factors at baseline that are associated with an increased risk of swallowing dysfunction and complications. METHODS: We prospectively assembled an inception cohort of 128 hospital-referred patients with acute first stroke. We assessed swallowing function clinically and videofluoroscopically, within a median of 3 and 10 days, respectively, of stroke onset, using standardized methods and diagnostic criteria. All patients were followed up prospectively for 6 months for the occurrence of death, recurrent stroke, chest infection, recovery of swallowing function, and return to normal diet. RESULTS: At presentation, a swallowing abnormality was detected clinically in 65 patients (51%; 95% CI, 42% to 60%) and videofluoroscopically in 82 patients (64%; 95% CI, 55% to 72%). During the subsequent 6 months, 26 patients (20%; 95% CI, 14% to 28%) suffered a chest infection. At 6 months after stroke, 97 of the 112 survivors (87%; 95% CI, 79% to 92%) had returned to their prestroke diet. Clinical evidence of a swallowing abnormality was present in 56 patients (50%; 95% CI, 40% to 60%). Videofluoroscopy was performed at 6 months in 67 patients who had a swallowing abnormality at baseline; it showed penetration of the false cords in 34 patients and aspiration in another 17. The single independent baseline predictor of chest infection during the 6-month follow-up period was a delayed or absent swallowing reflex (detected by videofluoroscopy). The single independent predictor of failure to return to normal diet was delayed oral transit (detected by videofluoroscopy). Independent predictors of the combined outcome event of swallowing impairment, chest infection, or aspiration at 6 months were videofluoroscopic evidence of delayed oral transit and penetration of contrast into the laryngeal vestibule, age >70 years, and male sex. CONCLUSIONS: Swallowing function should be assessed in all acute stroke patients because swallowing dysfunction is common, it persists in many patients, and complications frequently arise. The assessment of swallowing function should be both clinical and videofluoroscopic. The clinical and videofluoroscopic features at presentation that are important predictors of subsequent swallowing abnormalities and complications are videofluoroscopic evidence of delayed oral transit, a delayed or absent swallow reflex, and penetration. These findings require validation in other studies.

Aged↗
PubMed1996

Swallowing dysfunction in patients receiving prolonged mechanical ventilation.

Several studies have suggested that swallowing dysfunction and pulmonary aspiration occur in patients receiving prolonged ventilation. However, the incidence of swallowing dysfunction, its rate of resolution, and the sensitivity of tests used to characterize swallowing abnormalities are not well defined. The goals of our study were to evaluate swallowing function in this group of patients by (1) defining the specific swallowing abnormalities that occur in this patient population, (2) comparing the sensitivity of bedside evaluations to modified barium swallow with videofluoroscopy (MBS/VF), (3) performing endoscopic evaluation of the upper airway to characterize glottic function during swallowing, (4) evaluating the relationship between swallowing dysfunction and neuromuscular disorders, and (5) studying the temporal resolution of swallowing abnormalities. Swallowing function was evaluated in 35 patients receiving prolonged ventilation (ie, > or = 3 weeks) admitted to a specialized rehabilitation unit dedicated to the care of patients requiring prolonged ventilation. The average age of the 35 patients was 61 +/- 15 years. The total duration of intubation at the time of the initial swallowing evaluation was 29 +/- 34 days via a cuffed tracheostomy tube and 15 +/- 9 days via an endotracheal tube. Neuromuscular disorders were present in 16 patients (45%). Thirty-four percent of the patients had at least one swallowing abnormality detected by bedside examination. Results of bedside swallowing examination were abnormal in 31% of patients with a neuromuscular disorder and 37% of patients without a neuromuscular disorder. MBS/VF was abnormal in 83% of patients (85% in patients with and 80% in patients without a neuromuscular disorder). Results of early (< 1 month) repeated MBS/VF examinations usually remained unchanged; however, in a small group of patients, later studies (> or = 1 month) revealed significant improvement. In 50% of patients who underwent direct laryngoscopy, important abnormalities were found that contributed to swallowing dysfunction. Our data show that patients requiring prolonged mechanical ventilation have a high incidence of swallowing abnormalities, regardless of the presence or absence of neuromuscular disorders. MBS/VF and direct laryngoscopy can provide useful information about laryngeal action and swallowing dysfunction, and can facilitate the implementation of corrective actions to prevent respiratory complications.

Barium Sulfate↗
PubMed2005

Breathing and swallowing dynamics across the adult lifespan.

BACKGROUND: Aberrations in the physiologic components of normal oropharyngeal swallowing have been linked to aspiration events and to predisposition to aspiration pneumonia, a common, deadly disease in elderly persons. Studies have demonstrated a temporal, physiologic link between breathing and the principal physiologic swallowing components involved in airway protection during swallowing. We developed a normative model of integrated breathing and swallowing patterns using concomitant videofluoroscopic images and nasal respiratory airflow recordings. OBJECTIVES: To establish normative temporal and respiratory-phase pattern relationships between breathing and swallowing in adult human beings across the aging continuum; to relate any alterations in these patterns to swallowing abnormality, an aspiration event during swallowing, and predisposition to aspiration pneumonia; and to develop clinically practical evaluation methods for identifying breathing and swallowing discoordination. SETTING: Fluoroscopy suite in an acute care hospital. PARTICIPANTS: Eighty-two healthy adult volunteers gave informed consent. All eligible healthy volunteers were welcome and were screened for age, race, and sex for equal distribution of each. INTERVENTION: Respiratory-phase patterns and the onset and duration of 11 predetermined swallowing events and associated respiratory activities were studied. All participants' single-liquid barium swallow examinations were studied with simultaneous videofluoroscopy and respiratory recordings. MAIN OUTCOME MEASURES: Onset of each of the 11 predetermined breathing and swallowing events was digitally recorded and analyzed. The phases of breathing before and after swallowing were identified. The presence, depth, and response to airway penetration were recorded and related to respiratory pattern. RESULTS: Four respiratory-phase patterns were identified that changed with advanced age. The correlation analyses of the temporal breathing and swallowing events revealed a normal pattern of 4 clearly distinguishable functional units. Differences in apnea duration and apnea offset occurred with advanced age. CONCLUSION: This research provides evidence for clearly distinguishable patterns and functional groupings of breathing and swallowing events, a necessary first step toward determining whether abnormal breathing and swallowing patterns in patients with dysphagia are associated with health outcome.

Adult↗
PubMed2001

Swallowing physiology of sequential straw drinking.

The goal of this study was to examine deglutitive physiology during sequential straw drinking in healthy young adults (n = 15) to learn how sequential swallowing differs from single swallows. The physiology of single swallows has been studied extensively in healthy adults and in adults with a variety of debilitating conditions, but the physiology of sequential swallows has not been studied adequately. Videofluoroscopic analysis revealed three distinct patterns of hyolaryngeal complex (HLC) movement during sequential straw swallows: opening of the laryngeal vestibule after each swallow (Type I, 53%), continued vestibule closure after each swallow (Type II, 27%), and interchangeable vestibule opening and closing during the swallow sequence (Mixed, 20%). Unlike discrete swallowing, the onset of the pharyngeal swallow occurred when the bolus was inferior to the valleculae in the majority of subjects and was significantly associated with HLC movement pattern. The leading bolus edge was inferior to the valleculae at swallow onset for Type II movement patterns. For Type I movement patterns, bolus position at swallow onset was randomly distributed between three anatomical positions: superior to the valleculae, at the level of the valleculae, and inferior to the valleculae. Preswallow pharyngeal bolus accumulation, which is common during mastication, was evident and significantly associated with the HLC pattern of opened laryngeal vestibule after each swallow. These data suggest that in healthy young adults, sequential swallows differ physiologically from discrete swallows and indicate substantial variability in deglutitive biomechanics.

Adult↗
PubMed2001

Voluntary and reflex influences on the initiation of swallowing reflex in man.

The electrophysiological features of voluntarily induced and reflexive/spontaneous swallows were investigated. In normal subjects, swallows were elicited by infusing water either into the mouth (1-3 ml) or directly into the oropharyngeal region through a nasopharyngeal cannula (0.3-1 ml). For water infused orally, subjects were either requested to swallow voluntarily or instructed to resist swallowing and maintain the horizontal head position until swallowing occurred reflexively. Spontaneous saliva swallowing was investigated in patients with severe dysphagia who had a prominent clinical picture of suprabulbar palsy. Comparisons between different swallowing types were made by measuring the time interval between the onset of submental electromyographic activity (SM-EMG) and the onset of the upward movement of the larynx recorded by a movement sensor. This interval was less than 100 ms, even frequently less than 50 ms, in reflexive/spontaneous swallows, while in voluntarily induced swallows it was substantially longer. The rising time of submental muscle's excitation was also shorter in reflexive/spontaneous swallows. It was suggested that the triggering of voluntarily induced swallows commences more than 100 ms before the onset of swallowing reflex and that this mechanism is under the control of corticobulbar-pyramidal pathways. If the swallowing reflex is triggered within such a short period of time following the onset of SM-EMG, the central control by the bulbar swallowing center should be effective until the end of oropharyngeal swallowing.

Adult↗
PubMed1987

Responses of the human esophagus to paired swallows.

The present study was performed to characterize the interaction between two closely timed swallows, with particular attention being paid to short swallow intervals (less than 6-8 s) when the first wave is still traversing the esophagus and the effect of afferent stimulation in the form of bolus size. The contractile response of the esophagus to paired swallows (2-8 ml) over a range of swallow intervals (1.5-20 s) was studied in 13 normal humans using a 7-lumen perfused manometry catheter. At the shortest swallow intervals (less than 4 s), the first swallow wave is arrested in the striated muscle, while the second progresses normally. As swallow intervals lengthen (3-8 s), the first wave is arrested in the striated muscle, or is arrested or attenuated in the smooth muscle esophagus, but can continue for up to 3 s after initiation of the second swallow. The second wave is then arrested in the striated muscle, while beyond, a rapid or nonperistaltic low-amplitude wave occurs 3-5 s after the second swallow. At longer swallow intervals (greater than 6-8 s), the nonperistaltic second wave is replaced abruptly by a low-amplitude peristaltic wave of low velocity that traverses the entire esophagus. A larger first bolus increases the swallow interval required for this abrupt change, whereas a larger second bolus shortens the interval. The larger second bolus also increases the amplitude and decreases the velocity of the peristaltic second wave in both striated and smooth muscle portions. At swallow intervals greater than 10-15 s, two normal peristaltic waves occur. These studies demonstrate that each swallow of a closely timed pair directly affects the other. Not only does the second wave inhibit the first, but the first swallow and its wave markedly affect the second swallow wave. These interactions involve both the striated and the smooth muscle esophagus, and the latter interaction in particular is highly sensitive to afferent stimulation. This suggests that the interactions are predominantly neurogenic and have a significant central neural component.

Deglutition↗
PubMed2005

The influence of product and oral characteristics on swallowing.

The urge to swallow food could be triggered by a threshold level in both food particle size and lubrication of the food bolus. Thus, both oral physiology and product characteristics may influence the swallowing threshold. We quantified the swallowing threshold in a group of 266 healthy adult subjects (age 42 +/- 12 years) by counting the number of chewing cycles needed to prepare food for swallowing. The influence of oral physiology on the swallowing threshold was determined by measuring salivary flow rate, maximum bite force and masticatory performance. We used about 10 cm(3) of bread, toast, melba toast, breakfast cake, peanuts and cheese to determine the influence on the swallowing threshold of various food characteristics, e.g. hardness, moisture and fat. Furthermore, we tested the effect of buttering the bread, toast, melba toast and breakfast cake on the swallowing threshold. Salivary flow rates were significantly and negatively correlated with the number of chewing cycles of melba toast and breakfast cake. Hence, subjects with more saliva needed less chewing cycles for these dry products. Maximum bite force and masticatory performance had an influence on the swallowing threshold for the hard products only (carrot and peanut). Although significant, the correlation coefficients were less than 0.28. Thus, the oral physiology parameters explained less than 10% of the variance in the swallowing threshold. We found significantly different numbers of chewing cycles for the various foods, ranging from 17 for cake to 63 for carrot. Hard and dry products needed more chewing cycles until swallowing. Buttering the food significantly reduced the number of chewing cycles needed before swallowing. This was especially true for the dry products cake, melba toast and toast. Hard and dry products require more chewing cycles and longer time in mouth until swallowing for sufficient breakdown to take place and for enough saliva to be added to form a coherent bolus safe for swallowing. In spite of this, more saliva, higher maximum bite force and better masticatory performance were only weakly correlated with a smaller number of chewing cycles. Butter enhanced lubrication and bolus formation of dry products, thus reducing the number of chewing cycles until swallowing. In conclusion, product characteristics and to a lesser extent oral physiology significantly affect swallowing threshold.

Adult↗
PubMed2004

Surface electromyographic studies of swallowing in normal subjects: a review of 440 adults. Report 1. Quantitative data: timing measures.

OBJECTIVE: Surface electromyographic studies were performed on 440 normal adults to establish normative database for duration of muscle activity during swallowing and drinking clinically useful for outpatient ENT department. STUDY DESIGN: Prospective observational study of healthy volunteers. METHODS: Parameters evaluated during swallowing include the timing of activity of the orbicularis oris, masseter, submental, and infrahyoid muscle groups covered by platisma. Five tests were examined including voluntary single swallows of saliva ("dry" swallow), voluntary single water swallows as normal, voluntary single swallows of excessive amount of water (20 mL), continuous drinking of 100 mL of water (duration and number of swallows), monitoring of spontaneous swallowing of saliva during 1 hour period. The duration of oral, pharyngeal, and initial esophageal stages of swallowing (mean + SD) were measured for groups of adults of different age (18-30, 31-40, 41-50, 51-60, 61-70, 70+ years old). RESULTS: Normative data for duration of muscle activity during single swallowing and continuous drinking are established for healthy adults. The duration of swallows and drinking in all tests showed insignificant increase with the age except for the geriatric group, in which this tendency is statistically significant (1-dimensional analysis of variance, SPSS, Chi-square criterion, 95% confidence interval). There was no statistically significant difference between male and female adults duration of muscle activity during single swallowing and continuous drinking in all age groups (P >/= 0.05). The relevance and clinical utility of new and alternative measures, in particular, are discussed. CONCLUSION: Surface EMG of swallowing is a simple and reliable noninvasive method for screening evaluation of swallowing with low level of discomfort during the examination. Stage-by-stage evaluation of duration can be very important for topical diagnosis of etiology of dysphagia. The normative timing of events data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in preoperative and postoperative stages and in EMG monitoring during ENT treatment. These parameters represent stages required for normal deglutition, and can be used to identify abnormalities in ENT patients, and provide a basis for comparison of swallowing performance both within and between patients.

Adolescent↗
PubMed2004

Surface electromyographic studies of swallowing in normal subjects: a review of 440 adults. Report 3. Qualitative data.

OBJECTIVE: Surface electromyographic studies were performed on 440 normal adults to describe and evaluate different types of normal swallows clinically useful for ENT department. Study design Prospective observational study of healthy volunteers. METHODS: EMG recordings were made using stick-on surface electrodes. Rectified and filtered EMG signals were evaluated. Parameters evaluated include the graphic configuration of activity of the orbicularis oris, masseter, submental group, and infrahyoid muscles, the last 2 covered by platysma, during single swallowing and continuous drinking. Four tests were examined: voluntary saliva swallows, voluntary separate swallows as normal, voluntary separate swallows of excessive amount of water (20 mL), drinking of 100 mL of water. Graphic recording of activity of the above-mentioned muscles during swallowing and drinking were evaluated for groups of adults of different ages. RESULTS: There are several types of normal swallows as seen at the surface EMG records. There was no difference between EMG recordings of male and female swallows. Only group of elderly patients (age 70+) shows age-induced differences in recorded swallows. There are two main types of normal swallow: single-share and double-share swallows. The oral phase of swallowing, being under conscious control, is very variable and should not be taken into consideration during evaluation of records. Final oral, pharyngeal, and initial esophageal stages of swallowing can be defined and evaluated at the rectified and filtered surface EMG record. CONCLUSION: The normal muscle activity during swallows and drinking has several graphic patterns which can be identified and described similar to EKG records when surface EMG is rectified and filtered. The method of EMG recording is quick and simple, and can be used for screening and evaluation purposes in outpatient and inpatient ENT departments. These parameters represent activities required for normal deglutition, and can be used to identify abnormalities in ENT patients, and provide a basis for comparison of swallowing performance both within and between patients. These normal data form a valuable basis for future comparison with patients in pre- and postoperative stages and in EMG monitoring during ENT treatment.

Adolescent↗
PubMed2004

Effect of interval between swallows on oesophageal pressures and bolus movement in normal subjects - Studies with combined multichannel intraluminal impedance and oesophageal manometry.

The effect of closely spaced swallows to decrease peristalsis ('deglutitive inhibition') is believed to be due to both central inhibitory impulses and smooth muscle refractoriness. Ten volunteers (three females, age 26-65) were given both four pairs and two series of four swallows at 5-, 10-, 15-s intervals and control swallows at 30-s intervals. Oesophageal function was assessed using combined multichannel intraluminal impedance and oesophageal manometry (MII-OM). Swallows were considered manometrical effective if distal oesophageal pressures >/=30 mmHg. Complete bolus transit was defined as bolus exiting from all three distal impedance segments. During swallowing at 5-s intervals the majority of initial swallows were ineffective with incomplete bolus transit while the last swallow in both series and pairs was manometrically effective with complete bolus transit. During swallowing at 10-15-s intervals the number of manometric ineffective swallows and swallows with incomplete bolus transit progressively increased with the number of swallows. The functional information obtained by MII-OM indicates pooling of liquid in the distal oesophagus that is cleared by the last swallow determined by, previously reported, neural inhibition occurring during swallowing spaced 5 s apart whereas incomplete bolus transit is related to manometrically ineffective swallows resulting from muscle refractoriness occurring during swallowing at 10-15-s intervals.

Adult↗