Correlation on cine MR imaging of size of adenoid and palatine tonsils with degree of upper airway motion in asymptomatic sedated children

OBJECTIVE

The objective of this study was to use MR fluoroscopy to evaluate variations in size of the adenoid and palatine tonsils and the relationship between tonsil enlargement and airway motion dynamics in asymptomatic children during sleep.

SUBJECTS AND METHODS

We performed sagittal midline cine MR imaging (fast gradient-echo series: TR/TE, 8.2/3.6 sec; flip angle, 80 degrees; slice thickness, 8 mm; 128 consecutive images; imaging time, 2 min; displayed in cine mode) in children referred for MR imaging of the brain who required sedation. The largest transverse diameter of the adenoids was recorded. A subjective impression was made as to whether the adenoids were enlarged or normal in size. Palatine tonsils were considered enlarged when a soft-tissue mass was identified on the midline cine images, and maximum diameter was recorded. Enlarged and nonenlarged adenoid and palatine tonsil groups were compared using motion parameters (chi-square or Fisher's exact test): mouth position (opened or closed); vertical motion (present, absent); nasopharyngeal, oropharyngeal, and hypopharyngeal motion (static patent, dynamic patent, intermittent collapsed, or static collapsed, and greatest change in size).

RESULTS

We studied 148 subjects who had a mean age of 3.4 years. The adenoid tonsils were considered enlarged in 64 patients (43%), and the palatine tonsils were considered enlarged in 29 patients (20%). The mean size of the enlarged adenoid tonsils was 11.6 mm and of the nonenlarged adenoid tonsils was 6.2 mm. Enlarged adenoids correlated with the open mouth position (p = 0.0242) and increased dynamic motion of the oropharynx (p = 0.0413). A trend was also seen for increased dynamic motion of the nasopharynx (p = 0.0723). Enlarged palatine tonsils correlated with an increased frequency of dynamic motion of the oropharynx (p = 0.0006) and the nasopharynx (p = 0.0033) and a trend for increased frequency of the open mouth position (p = 0.0692).

CONCLUSION

Large adenoid and palatine tonsil size affects breathing dynamics of the upper airway even in asymptomatic children.

Oropharyngeal swallow in younger and older women: videofluoroscopic analysis

Much of the initial research on normal swallowing has been conducted in young men. Recently, there has been increasing interest in determining whether there are differences between the sexes in swallowing function and in the effects of aging on swallowing in both sexes. This investigation examined the swallowing ability of 8 healthy young women between the ages of 21 and 29 and 8 healthy older women between the ages of 80 and 93 during two swallows each of 1 ml and 10 ml liquid boluses. Videofluoroscopic studies of these swallows were reviewed in slow motion and real time to confirm the absence of swallowing disorders. Kinematic analysis of each swallow was completed. Data on range of motion of pharyngeal structures and coordination characteristics of the oropharyngeal swallow were taken from this kinematic analysis. Position of the larynx at rest and length of neck were compared between the two groups. Data from this study were compared with previously published data on younger and older men. Interestingly, the range of motion of the older women was often greater than that of the young women. Only tongue base movement diminished significantly with age in women. Volume effects observed in duration and extent of movement during the 1 ml and 10 ml swallows were similar to those in earlier studies. Older women also exhibited an increased range of motion relative to the old men. This increase may indicate a compensation for aging effects not seen in older men.

Magnetic resonance imaging of the levator veli palatini muscle during speech

OBJECTIVE

To obtain detailed anatomic information on the levator veli palatini (LVP) muscle from magnetic resonance imaging (MRI). Quantitative measures of the configuration of the LVP muscle at rest and during speech activities were obtained.

DESIGN

Prospective study using MRI of adult subjects with normal velopharyngeal mechanisms to determine anatomic and physiologic parameters of the levator muscle. The levator veli palatini muscle was imaged at rest and during speech activities consisting of nasal and non-nasal sounds mixed with vowels, consonants, or both (e.g., /ansa, asna, amfa, afma/).

PARTICIPANTS

Ten normal healthy adults (five men, five women) between 21 and 53 years of age and free of oropharyngeal abnormalities.

MAIN OUTCOME MEASURES

Two-dimensional spin echo static images and dynamic fast gradient echo images of the levator muscle in both the sagittal and oblique/coronal planes.

RESULTS

On average across female (F) and male (M) subjects: distance between LVP muscle origin points, 52.6 mm (F), 54.6 mm (M); angle of levator muscle origin at rest, 64.5 degrees (F), 60.4 degrees (M); length of the levator muscle at rest, 44.1 mm (F), 46.4 mm (M); width of levator muscle at lateral margin of velum, 5.5 mm (F), 6.6 mm (M). Both the levator muscle angle of origin and length became progressively smaller from rest, nasal consonants, low vowels, high vowels, and fricatives for both female and male subjects. Across all subjects, there was a 19% reduction in length of the LVP muscle from rest position to fricative production.

CONCLUSIONS

MRI is an effective method of imaging and measuring the LVP muscle and related structures in living subjects. Understanding the normal tissue distribution and quantification of the LVP muscle provides important information for development of a functional biomechanical model of the velopharynx and for improved surgical treatment.

Oropharyngeal swallowing variability

OBJECTIVES/HYPOTHESIS

The pharyngeal phase of deglutition is considered to occur in a reflexive, preprogrammed fashion. Previous studies have determined a general sequence of events based on the mean timing of bolus transit and swallowing gestures. However, individual variability has not been studied. The purpose of the present study was to evaluate the amount of sequence variability that normally occurs during the oropharyngeal phase of deglutition.

STUDY DESIGN

Prospective analysis of conservative subjects.

METHODS

Dynamic swallow studies from 60 normal volunteers were evaluated, and event sequence variability was determined around two event sequences during swallowing of three bolus sizes.

RESULTS

There was found to be substantial variability in event sequences for all events analyzed. Variability was greater during a smaller bolus swallow.

CONCLUSIONS

The evaluation of variability within the study group of individuals reveals the complexity of the swallowing mechanism and underscores the importance of not relying on general guidelines in evaluating the coordination of swallowing gestures in a given individual with dysphagia complaints.

Hyoid and tongue surface movements in speaking and eating

The human hyoid moves continuously in feeding, facilitating movements of the tongue surface and the processing and transport of food. The hypothesis that similar hyoid movements support tongue movements in speech was tested in 10 normal young adults of both sexes, who were recorded with lateral-projection videofluorography when feeding on hard and soft foods and when reading the 'Grandfather Passage', which includes the major vowel-consonant combinations in English. Recordings were made with and without tongue-markers. Images were analysed with a digital frame grabber and computer. Each participant served as his/her own control. The hyoid moved continuously during speech and feeding. In speech, hyoid motions were irregular and not linked to jaw movement, as they were for feeding. The centroids and variances of the domains for all reference points were compared for speech and feeding; the centroid represents the average position of a structure and variance its amount of motion. Gape and hyoid centroids were significantly different for feeding and speech (P<0.001), but differences for gape averaged <1mm while the difference for the hyoid centroid was >7mm. There were no significant differences in gape attributable to sex. Consistent with the known differences in hyolaryngeal position there were significant sex differences in hyoid centroid (P=0.031) but not variance. In speech, tongue-markers had a smaller spatial domain (P=0.001) condensed within the larger feeding domain. The small shift in the gape centroid does not explain the larger forward shift of the hyoid during speech. These findings raise questions about the neuromotor control of hyoid position in the two behaviours and the biomechanics of the supralaryngeal vocal tract.

Evaluation of the anatomical and functional properties of deglutition with various kinetic high-speed MRI sequences

We evaluated various fast MR sequences for obtaining anatomical and dynamic functional information during deglutition. Seven healthy volunteers underwent MRI of the oropharynx during swallowing of an oral positive-contrast agent. Single-slice imaging was performed in the median sagittal plane while subjects were in a supine position. Twenty serial images were obtained using EPI, FLASH, and turbo-FLASH sequences. The dynamic (movement-related) information and the anatomical resolution of the soft tissues were evaluated during deglutition. The FLASH sequence provided high-quality images at rest. During swallowing, however, the images were significantly degraded by movement artifacts and had inferior temporal resolution. The EPI evidenced better temporal resolution, but was degraded by strong distortions and movement artifacts. The turbo-FLASH sequence provided the best temporal resolution and sufficient spatial resolution during motion. This sequence proved optimal for the investigation of swallowing function, and is expected to be of value for the documentation of functional disturbances in patients with oropharyngeal pathology.

Effect of REM sleep on retroglossal cross-sectional area and compliance in normal subjects

It has been proposed that the upper airway compliance should be highest during rapid eye movement (REM) sleep. Evidence suggests that the increased compliance is secondary to an increased retroglossal compliance. To test this hypothesis, we examined the effect of sleep stage on the relationship of retroglossal cross-sectional area (CSA; visualized with a fiber-optic scope) to pharyngeal pressure measured at the level of the oropharynx during eupneic breathing in subjects without significant sleep-disordered breathing. Breaths during REM sleep were divided into phasic (associated with eye movement, PREM) and tonic (not associated with eye movements, TREM). Retroglossal CSA decreased with non-REM (NREM) sleep and decreased further in PREM [wake 156.8 +/- 48.6 mm(2), NREM 104.6 +/- 65.0 mm(2) (P < 0.05 wake vs. NREM), TREM 83.1 +/- 46.4 mm(2) (P = not significant NREM vs. TREM), PREM 73.9 + 39.2 mm(2) (P < 0.05 TREM vs. PREM)]. Retroglossal compliance, defined as the slope of the regression CSA vs. pharyngeal pressure, was the same between all four conditions (wake -0.7 + 2.1 mm(2)/cmH(2)O, NREM 0.6 +/- 3.0 mm(2)/cmH(2)O, TREM -0.2 +/- 3.3 mm(2)/cmH(2)O, PREM -0.6 +/- 5.1 mm(2)/cmH(2)O, P = not significant). We conclude that the intrinsic properties of the airway wall determine retroglossal compliance independent of changes in the neuromuscular activity associated with changes in sleep state.

Computer measurement of oral movement in swallowing

This article describes a computer program that automatically detects and tracks small metal markers affixed to a subject's tongue and teeth in fluoroscopic image sequences of swallowing. The program, written in Microsoft Visual C++ using Windows NT 4.0 and the SAVANT imaging toolkit, involves marker detection and marker tracking. Marker detection is done by template matching. A generic marker template was designed by extracting the grayvalues of pixels within an imaged marker. Template matching with a weighted center-of-mass calculation determined marker location with subpixel accuracy. Marker tracking employed a nearest-neighbor algorithm since (a) the movement of each marker was less than the distance between any two markers and (b) marker trajectories did not overlap. Effects of head motion were attenuated by computing tongue trajectories with respect to a constant frame of reference given by reference markers on the maxillary teeth. Motions were converted from pixels/frame to millimeters/second using a calibration ring secured to the subject's neck. Results for several image sequences showed that our program performs very well in terms of marker detection and trajectory determination. Comparison of automatic and manual tracking of the same image sequences indicated a high degree of correspondence. Automatic tracking of oral movement by computer is a useful tool in kinematic studies of swallowing.

A comparison of four methods for assessing oropharyngeal leak pressure with the laryngeal mask airway (LMA) in paediatric patients

BACKGROUND

This study compares four tests for assessing oropharyngeal leak pressure with the laryngeal mask airway (LMA). We tested the hypothesis that the oropharyngeal leak pressure and interobserver reliability differs between tests.

METHODS

Eighty paralysed anaesthetized paediatric patients (weight 10-30 kg) were studied with the intracuff pressure set at 60 cmH2O. Four different oropharyngeal leak pressure tests were performed in random order on each patient by two observers blinded to each other's measurements. Test 1 involved detection of an audible noise. Test 2 involved detection of endtidal CO2 in the oral cavity. Test 3 involved observation of the aneroid manometer dial as the pressure increased and noting the airway pressure at which the dial reaches stability. Test 4 involved detection of an audible noise by neck stethoscopy.

RESULTS

The mean oropharyngeal leak pressure was 12.5 cmH2O and was similar between tests. The intraclass correlation coefficient was 0.99 for all tests and was classed as excellent.

CONCLUSIONS

We conclude that all four tests provide accurate and reliable information about oropharyngeal leak pressure in children.

Changes in orofacial muscle activity in response to changes in respiratory resistance

Increased resistance in the upper airway is known to be a contributing factor to deviant facial growth patterns. These patterns are the result of a prolonged presence of unbalanced oropharyngeal muscle activity. We hypothesized that mechanically increasing airway resistance would enhance the activity of the muscles facilitating respiration, and we attempted to demonstrate that the increased muscle activity is modulated by mechanoreceptors in the pharyngeal airway. The response of oropharyngeal muscles to increased airway resistance during spontaneous breathing was observed in 11 rabbits. Electromyographic signals from the ala nasi, orbicularis oris superior, genioglossus, mylohyoid muscles, and the diaphragm were recorded by fine-wire electrodes. Pressure changes were monitored by pressure transducers at the side branch of the cannule close to openings for the nose and the trachea. The study consisted of 2 experimental sessions. First, to evoke the response of muscles to the inspiratory resistance, increasing stepwise polyethylene tubes of various diameters were attached to the nasal and tracheal opening and the diameter of the tubes was gradually reduced. Muscle activity changes in response to the increased resistance were recorded during spontaneous nasal or tracheal breathing. Second, to examine muscle responses to negative pressure to the pharyngeal airway, irrespective of breathing activity, the pharynx was isolated as a closed circuit by a stoma constructed at a more caudal side in the trachea. Muscle responses to the negative pressure generated by a syringe in the pharyngeal segment were measured. Nasal breathing induced a greater muscle activity than did tracheal breathing, in general, at P <.05. When resistance was gradually increased, nasal breathing resulted in a greater increase in muscle activity than did tracheal breathing (P <.05), except in the diaphragm. Application of negative pressure to the isolated pharyngeal airway segment increased the muscle activity significantly (P <.05). We conclude that an increased airway resistance may facilitate oropharyngeal muscle activity through mechanoreceptors in the oropharyngeal airway.

Methodology for the measurement of mucociliary function in the mouse by scintigraphy

The objective of the study was to develop a scintigraphic method for measurement of airway mucociliary clearance in small laboratory rodents such as the mouse. Previous investigations have characterized the secretory cell types present in the mouse airway, but analysis of the mucus transport system has been limited to in vitro examination of tissue explants or invasive in vivo measures of a single airway, the trachea. Three methods were used to deposit insoluble, radioisotopic colloidal particles: oropharyngeal aspiration, intratracheal instillation, and nose-only aerosol inhalation. The initial distribution of particles within the lower respiratory tract was visualized by gamma-camera, and clearance of particles was followed intermittently over 6 h and at the conclusion, 24 h postdelivery. Subsets of mice underwent lavage for evidence of tissue inflammation, and others were restudied for reproducibility of the methods. The aspiration and instillation methods of delivery led to greater distributions of deposited activity within the lungs, i.e., approximately 60--80% of the total respiratory tract radioactivity, whereas the nose-only aerosol technique attained a distribution of 32% to the lungs. However, the aerosol technique maximized the fraction of particles that cleared the airway over a 24-h period, i.e, deposited onto airway epithelial surfaces and cleared by mucociliary function such that lung retention at 24 h averaged 57% for delivery by aerosol inhalation and > or =80% for the aspiration or intratracheal instillation techniques. Particle delivery methods did not cause lung inflammation/injury with use of inflammatory cells and chemoattractant cytokines as criteria. Scintigraphy can discern particle deposition and clearance from the lower respiratory tract in the mouse, is noninvasive and reproducible, and includes the capability for restudy and lung lavage when time course or chronic treatments are being considered.

Influence of head and neck position on cuff position and oropharyngeal sealing pressure with the laryngeal mask airway in children

We studied how head and neck position affect the cuff position and oropharyngeal sealing pressures of the laryngeal mask airways (LMAs) in children. We studied 39 non-paralyzed healthy children aged 1.5-8.0 yr, weighing 10.3-27.0 kg, managed with size 2 or 2.5 LMAs during elective surgery. Head and neck movements did not adversely affect airway patency in 97% of patients. One child developed apparent airway obstruction with head and neck flexion, which was relieved in the neutral position. Oropharyngeal sealing pressure was significantly greater during neck flexion compared with the neutral position (P<0.02). Fibreoptic examination revealed that the epiglottis covered a larger area of the LMA aperture during neck flexion, compared with the neutral position (P<0.02).

Effect of mucosal anaesthesia on oropharyngeal swallowing

The effect of the topical anaesthesia of the oropharyngeal mucosae was studied in order to evaluate the role of the mucosal sensory receptors on the oropharyngeal swallowing in 12 adult volunteers. Laryngeal vertical movements were detected by a piezoelectric sensor and electromyography of the submental muscle complex were simultaneously recorded. All subjects were instructed to swallow doses of water, gradually increasing in quantity from 3-20 mL and any recurrence of the signals related to swallowing within 8 s was accepted as a sign of dysphagia and its limit value measured. Before the topical anaesthesia of the oropharyngeal mucosae by xylocaine puffs; the dysphagia limit was never observed with less than 20 mL water. During topical mucosal anaesthesia lasting 4-6 min among the subjects, the dysphagia limit was less than 20 mL water and the recurrence of swallows two or more times was mainly recorded with 3-5 mL water. Five of the subjects demonstrated the clinical and electrophysiological signs of laryngeal aspiration at the earlier period of the topical anaesthesia. It is concluded that the sensory inputs from the mucosal receptors are important to trigger voluntary swallowing and their absence or dysfunction may contribute to oropharyngeal dysphagia and laryngeal aspiration.

[Cold and warm thermoregulation by oropharynx area and esophagus]

After being ingested, food and liquids suffer a thermal regulation process, which adapts them immediately to the body temperature by means of the mucosa diffusion. We have not found bibliographical information about this matter yet.

OBJECTIVES

1) To describe the reaction of the oropharynx area and the esophagus by heat and coldness. 2) To compare both areas reaction.

STUDY POPULATIONS

Six patients (three men, three women, Age: mean 42 years old, SD 11.8), healthy individuals without both gastrointestinal and systemic disease that could after microcirculation.

MATERIALS & METHODS

Temperature measurement of liquid at mouth entrance and at 24 cm and 38 cm from dentary superior arcade using two thermocouples. Deglution of 40 ml of hot water (X 60 degrees C at entrance) or cold water (X 4 degrees C) in two draughts. Temperature measurement at both thermocouples at the end of deglution (time = 0 (zero)) and every 10 seconds. Random sequences every 30 minutes.

RESULTS

Using water at 60 degrees C, the temperature descended to 42 degrees C in the distal end. The oropharynx region dissipated 45% of the initial temperature while the esophagus completed the other 55%. The esophagus itself dissipated 65.6% of the 12.2 degrees C in time = 0 (zero). After 40 seconds the temperature reached the normal body temperature. In the case of the iced water (4 degrees C), the total work consisted on increasing temperature 33.6 degrees C to the normal corporal temperature. The 68.45% of the difference between the initial and the final temperature was obtained by the oropharynx region and the rest by the esophagus. In time = 0 (zero) the temperature increased up to 30 degrees C and the esophagus only contributed with 28.3% of the total work. The normal corporal temperature was reached after 40 seconds. It was observed a significant difference in the heating capacity between the oropharynx region and esophagus (p > 0.001). There was also a significant difference in the oesophagus itself between heat and coldness in time = 0 (zero) ¿65.6% (heat) Vs. 28.3% (coldness), 0.02 > p > 0.01¿ and values between time = 0 (zero) and 10-40 seconds (p > 0.001).

CONCLUSION

1) The ability of cooling was similar in both regions. 2) In the oropharynx region the capacity of heating was higher (voluntary time of deglution) than in the esophagus region. 3) The esophagus initial response before coldness was slower than oropharynx region's one. The buccal retention was greater. 4) Before both stimulus, normal corporal temperature was reached after 40 seconds.

COMMENTARY

The isothermation of coldness and heat would work through the same mechanism: the mucosa vasodilatation and the increase of blood flow. This hypothesis would be valid for all the mucosa of the digestive tract. This mechanism could be altered in inflammatory diseases. Iced water washings on bleeding wounds be counter-productive. The persistence of extreme temperatures in the environment modifies the structure of the esophagus mienteric plexus (Auerbach's plexus). Frequent ingestion of fluids above 60 degrees C would be a predisponent factor for esophagus cancer.

Temporal and biomechanical characteristics of oropharyngeal swallow in younger and older men

As the U.S. population ages, there is increasing need for data on the effects of aging in healthy elderly individuals over age 80. This investigation compared the swallowing ability of 8 healthy younger men between the ages of 21 and 29 and 8 healthy older men between the ages of 80 and 94 during two swallows each of 1 ml and 10 ml liquid. Videofluoroscopic studies of these swallows were analyzed to confirm the absence of swallowing disorders. Biomechanical analysis of each swallow was completed, from which data on temporal, range of motion, and coordination characteristics of the oropharyngeal swallow were taken. Position of the larynx at rest, length of neck, and pattern of hyoid bone movement were also compared between the two groups. None of the younger or older men exhibited any swallowing disorders. The C2 to C4 distance of older men was significantly shorter than that of younger men, and laryngeal position at rest was lower than in younger men but not significantly so. Older men had a significantly longer pharyngeal delay than younger men and significantly faster onset of posterior pharyngeal wall movement in relation to first cricopharyngeal opening. The older men exhibited significantly reduced maximum vertical and anterior hyoid movement as compared to the younger men even when accounting for the difference in C2 to C4 distance in older men. These data support the hypothesis of reduced muscular reserve in the swallows of older men as compared to younger men. Older men also exhibited less width of cricopharyngeal opening than younger men at 10 ml volume, indicating less upper esophageal sphincter flexibility in the swallows of older men. The potential for exercise to improve reserve is discussed. Significant changes in extent of hyoid elevation and duration of cricopharyngeal opening were seen as liquid bolus volume increased.

Supine cephalometric study on sleep-related changes in upper-airway structures in normal subjects

The purpose of this study was to examine sleep-related changes in the upper airway and surrounding structures including the mandible, hyoid bone, and cervical vertebra in normal subjects using lateral cephalograms in the supine position. Eleven male and nine female healthy adults participated in this study. Supine cephalograms were taken at end-expiration during wakefulness and in stage 1-2 non-rapid-eye-movement (NREM) sleep judged from the electroencephalogram and respiratory monitoring. A paired t-test was used to compare differences between the values measured during wakefulness and sleep. A significant increase in the amount of jaw opening was observed during sleep. The anteroposterior width of the upper airway was significantly decreased during sleep. The distances between the hyoid bone and the mandibular symphysis and between the cervical vertebra and the hyoid bone were significantly decreased during sleep. Consequently, the distance between the cervical vertebra and the mandibular symphysis was significantly decreased. These results suggest that the upper-airway dimension is significantly decreased and relatively small structural changes are induced during sleep in normal subjects.

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

BACKGROUND & AIMS

The functional role of brainstem nitric oxide (NO) in swallowing and esophageal peristalsis remains unknown. We examined the effects of blockade of central nervous system (CNS) NO synthase (NOS) on swallowing and on primary and secondary peristalsis.

METHODS

(1) The effect of intravenous (IV) NOS inhibitor N(G)-nitro-L-arginine (L-NNA) on swallowing and swallowing-induced peristalsis was examined. (2) An NOS inhibitor (N(G)-monomethyl-L-arginine [L-NMMA]) was administered into the fourth ventricle intracerebroventricularly (ICV), and its effects on swallowing and primary and secondary peristalsis were examined.

RESULTS

(1) IV L-NNA significantly reduced the number of oropharyngeal swallows and the induction of primary peristalsis in the smooth muscle portion of the esophageal body; the change was not significant within the striated muscle portion. (2) L-NMMA given ICV significantly reduced the number of oropharyngeal swallows and the incidence of primary peristalsis in both smooth and striated muscle, but the reduction in amplitude was significant only for the smooth muscle contraction. There was a significant reduction in both the amplitude and incidence of secondary peristalsis, only in the smooth muscle portion.

CONCLUSIONS

CNS NO is an important neurotransmitter in the induction of oropharyngeal swallowing and esophageal peristalsis. The neural substrates mediating striated and smooth muscle peristalsis may be both anatomically and neurochemically distinct.

Timing of events in normal swallowing: a videofluoroscopic study

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for clinically useful timing measures. The relation of swallowing gesture timing to the timing of actual bolus transit was of particular interest because it provides insight into the physiology of larger bolus volume accommodation. Parameters evaluated include the timing of bolus pharyngeal transit, soft palate elevation, aryepiglottic fold elevation and supraglottic closure, arrival of the bolus in the vallecula, hyoid bone displacement onset and duration, arrival of the bolus at the pharyngoesophageal sphincter, maximum pharyngeal constriction, and pharyngoesophageal sphincter opening. These parameters represent events required for normal deglutition, can be used to identify abnormalities in dysphagic patients, and provide a basis for comparison of swallowing performance both within and between patients. In addition, our experience has shown them to be reliably obtained. Other investigators have reported some of the measurements. However, to our knowledge, normative data for timing of aryepiglottic fold elevation, soft palate elevation and closure, and maximum pharyngeal constriction have not been described. Other measures included in the present study may provide alternatives when conventional measures cannot be obtained in selected patients. The relevance and clinical utility of new and alternative measures, in particular, are discussed.

Respiratory and acoustic signals associated with bolus passage during swallowing

In order to advance our understanding of the relation between respiration and deglutition, simultaneous videofluoroscopy and respirodeglutometry was performed. Fifteen normal, healthy, young adults (20-29 years of age) were connected to a respirodeglutometer and positioned for simultaneous videofluoroscopic assessment in the lateral plane. Subjects performed three swallows each of a 5-ml and a 10-ml bolus of liquid barium and a 5-ml bolus of paste barium, for a total of nine swallows per subject. Location of the bolus head as identified with videofluoroscopy was associated with eight respirodeglutometric variables. In addition, temporal relations for seven respirodeglutometric variables were calculated as a function of bolus volume and viscosity. Significant temporal differences were found for five of the variables by volume. No significant temporal differences were noted by viscosity. Expiration occurred before 79% and after 96% of the swallows. The number of inspirations preceding a swallow suggested a possible effect resulting from the need to hold a bolus in the mouth before receiving instructions to swallow during videofluoroscopic assessment. This effect may be important during patient evaluation. For a significant number of swallows, respiratory flow ceased before the velum was fully elevated.

Sensory nerve supply of the human oro- and laryngopharynx: a preliminary study

To date, the details of human sensory innervation to the pharynx and upper airway have not been demonstrated. In this study, a single human oro- and laryngopharynx obtained from autopsy was processed with a whole-mount nerve staining technique, Sihler's stain, to determine its entire sensory nerve supply. The Sihler's stain rendered all mucosa and soft tissue translucent while counterstaining nerves. The stained specimen was then dissected and the nerves were traced from their origins to the terminal branches. It was found that the sensory innervation of the human pharynx is organized into discrete primary branches that innervate specific areas, although these areas are often connected by small neural anastomoses. The density of innervation varied, with some areas receiving almost no identifiable nerve supply (e.g., posterior wall of the hypopharynx) and certain areas contained much higher density of sensory nerves: the posterior tonsillar pillars; the laryngeal surface of the epiglottis; and the postcricoid and arytenoid regions. The posterior tonsillar pillar was innervated by a dense plexus formed by the pharyngeal branches of the IX and X nerves. The epiglottis was densely innervated by the internal superior laryngeal nerve (ISLN) and IX nerve. Finally, the arytenoid and postcricoid regions were innervated by the ISLN. The postcricoid region had higher density of innervation than the arytenoid area. The use of the Sihler's stain allowed the entire sensory nerve supply of the pharyngeal areas in a human to be demonstrated for the first time. The areas of dense sensory innervation are the same areas that are known to be the most sensitive for triggering reflex swallowing or glottic protection. The data would be useful for further understanding swallowing reflex and guiding sensory reinnervation of the pharynx to treat neurogenic dysphagia and aspiration disorders.

Advancement of the mandible facilitates nasal breathing in human subjects sedated with midazolam

PURPOSE

To determine how anterior advancement of the mandible (ADM) affects spontaneous breathing through the nasal route in healthy human volunteers sedated with intravenous midazolam.

METHODS

In four subjects who exhibited nasal breathing during midazolam sedation (intravenous dose: 0.09+/-0.02 mg x kg(-1), mean +/- SD), we measured respiratory rate (RR), peak nasal inspiratory airflow rate (V(nIpeak)) peak nasal expiratory airflow rate (V(nEpeak), duty ratio (Ti/Ttot) and nasal resistance (Rn) before and after ADM. Nasal resistance was calculated by dividing the difference between nasal mask and oropharyngeal pressure by airflow rate at peak nasal inspiratory airflow.

RESULTS

The RR, V(nIpeak), and V(nEpeak) increased following ADM (P<0.001, respectively). On the contrary, Ti/Ttot decreased after ADM (P<0.001). Consequently, ADM decreased Rn from 30.4+/-40.8 to 5.0+/-5.6 (cm H2O x l(-1) x sec(-1)) (mean +/- SD) (P<0.001). In these four subjects, no respiratory airflow was observed through the oral route before and after ADM.

CONCLUSION

Advancement of the mandible decreases nasal resistance, thereby facilitating spontaneous breathing through the nasal route in normal humans sedated with midazolam.

Role of laryngeal movement and effect of aging on swallowing pressure in the pharynx and upper esophageal sphincter

OBJECTIVES

Describe contribution of laryngeal movement to pressure changes at the upper esophageal sphincter (UES) and the effect of aging on the swallowing function.

STUDY DESIGN

Manofluorography on 56 nondysphagic adults divided into three age groups: the 21- to 31-year-old group (n = 32), the 61- to 74-year-old group (n = 12) and the 75- to 89-year-old group (n = 12). Analyses of the bolus transit time, the amplitudes and durations of pharyngeal pressures, the timing of a pressure fall at the UES and the laryngeal movements.

METHODS

Intraluminal strain-gauge sensors recorded pressure changes in the oropharynx, hypopharynx and the UES. Motion pictures of the videotapes were fed into a personal computer, and movements of the hyoid bone were measured in both the horizontal and vertical directions as an indication of laryngeal movement.

RESULTS

In 26- and 70-year-old men with calcification of the thyroid cartilage, it was determined that the larynx and hyoid bone moved in consonance until the end of the rapid hyoid movements in both the superior and anterior directions. In the 21- to 31-year-old group, the magnitude of the pressure fall at the UES was maximal before or almost at the same time as the bolus arrival, in preparation for smooth passage of the bolus from the pharynx to the esophagus. The rapid superior movements of the hyoid bone started significantly early as compared with its anterior movements (P = .0001). The rapid anterior movements of the hyoid bone started simultaneously with the pressure fall at the UES. In the elderly, all segmental transit times were significantly increased. The timing of the pressure fall at the UES was significantly delayed and the UES pressure reached its minimum value after arrival of the bolus at the UES. The minimum pressure at the UES increased to a significantly positive value. The rapid anterior movements of the hyoid were significantly delayed, suggesting that this delay causes the delay in the pressure fall at the UES.

CONCLUSIONS

The rapid superior and anterior movements of the hyoid bone are considered to start at the same time as those of the larynx. In the young group, it is suggested that superior laryngeal movement protects the lower airway prior to the anterior laryngeal movement, causing the pressure fall at the UES to enable the passage of a bolus into the UES. In the elderly, smooth passage of the bolus from the pharynx to the esophagus is hindered and the system that prevents aspiration is rendered inefficient by changes in the swallowing pressures and laryngeal movements with aging.

Diagnosing respiratory events and tracing air flow by internal thermistors

We have developed a new method to measure flow in patients with sleep-related breathing disorders (SRBD). These flow sensors are modified thermistors located in the same sensors we use for pressure measurement in the upper airways to find the obstructive segments during apnoeas. The aim of this study was to test if using internal thermistors as indicator of air flow has advantages compared with the external thermistor method in detecting respiratory events. A total of 50 consecutive patients with an apnoea-hypopnoea index (AHI) of more than 15 were studied. A standard nocturnal polysomnography (PSG) with both internal and external thermistors was performed in all patients. To estimate the patients' AHI, a detailed analysis viewing all parameters except external and internal thermistors was performed. This was followed by an analysis viewing only internal thermistors signals indicating airflow in the pharynx, and finally an analysis viewing only external thermistor signals indicating air flow at the mouth and nose. Mean AHI measured by the three methods showed 49.8 (SD 23.4) by the PSG, 47.8 (SD 24.9) by internal thermistors alone, and 31.5 (SD 22.2) by external thermistors. There was no statistical difference between AHI detected by PSG and internal thermistors, but highly significant differences between PSG and external thermistors (p < 0.001). The external thermistors missed an average of almost 20 respiratory events per hour.