Myofunctional therapy (oropharyngeal exercises) for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is a syndrome characterised by episodes of apnoea (complete cessation of breathing) or hypopnoea (insufficient breathing) during sleep. Classical symptoms of the disease - such as snoring, unsatisfactory rest and daytime sleepiness - are experienced mainly by men; women report more unspecific symptoms such as low energy or fatigue, tiredness, initial insomnia and morning headaches. OSA is associated with an increased risk of occupational injuries, metabolic diseases, cardiovascular diseases, mortality, and being involved in traffic accidents. Continuous positive airway pressure (CPAP) - delivered by a machine which uses a hose and mask or nosepiece to deliver constant and steady air pressure- is considered the first treatment option for most people with OSA. However, adherence to treatment is often suboptimal. Myofunctional therapy could be an alternative for many patients. Myofunctional therapy consists of combinations of oropharyngeal exercises - i.e. mouth and throat exercises. These combinations typically include both isotonic and isometric exercises involving several muscles and areas of the mouth, pharynx and upper respiratory tract, to work on functions such as speaking, breathing, blowing, sucking, chewing and swallowing.

OBJECTIVES

To evaluate the benefits and harms of myofunctional therapy (oropharyngeal exercises) for the treatment of obstructive sleep apnoea.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from the Cochrane Airways Trials Register (date of last search 1 May 2020). We found other trials at web-based clinical trials registers.

SELECTION CRITERIA

We included RCTs that recruited adults and children with a diagnosis of OSA.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We assessed our confidence in the evidence by using GRADE recommendations. Primary outcomes were daytime sleepiness, morbidity and mortality.

MAIN RESULTS

We found nine studies eligible for inclusion in this review and nine ongoing studies. The nine included RCTs analysed a total of 347 participants, 69 of them women and 13 children. The adults' mean ages ranged from 46 to 51, daytime sleepiness scores from eight to 14, and severity of the condition from mild to severe OSA. The studies' duration ranged from two to four months. None of the studies assessed accidents, cardiovascular diseases or mortality outcomes. We sought data about adverse events, but none of the included studies reported these. In adults, compared to sham therapy, myofunctional therapy: probably reduces daytime sleepiness (Epworth Sleepiness Scale (ESS), MD (mean difference) -4.52 points, 95% Confidence Interval (CI) -6.67 to -2.36; two studies, 82 participants; moderate-certainty evidence); may increase sleep quality (MD -3.90 points, 95% CI -6.31 to -1.49; one study, 31 participants; low-certainty evidence); may result in a large reduction in Apnoea-Hypopnoea Index (AHI, MD -13.20 points, 95% CI -18.48 to -7.93; two studies, 82 participants; low-certainty evidence); may have little to no effect in reduction of snoring frequency but the evidence is very uncertain (Standardised Mean Difference (SMD) -0.53 points, 95% CI -1.03 to -0.03; two studies, 67 participants; very low-certainty evidence); and probably reduces subjective snoring intensity slightly (MD -1.9 points, 95% CI -3.69 to -0.11 one study, 51 participants; moderate-certainty evidence). Compared to waiting list, myofunctional therapy may: reduce daytime sleepiness (ESS, change from baseline MD -3.00 points, 95% CI -5.47 to -0.53; one study, 25 participants; low-certainty evidence); result in little to no difference in sleep quality (MD -0.70 points, 95% CI -2.01 to 0.61; one study, 25 participants; low-certainty evidence); and reduce AHI (MD -6.20 points, 95% CI -11.94 to -0.46; one study, 25 participants; low-certainty evidence). Compared to CPAP, myofunctional therapy may result in little to no difference in daytime sleepiness (MD 0.30 points, 95% CI -1.65 to 2.25; one study, 54 participants; low-certainty evidence); and may increase AHI (MD 9.60 points, 95% CI 2.46 to 16.74; one study, 54 participants; low-certainty evidence). Compared to CPAP plus myofunctional therapy, myofunctional therapy alone may result in little to no difference in daytime sleepiness (MD 0.20 points, 95% CI -2.56 to 2.96; one study, 49 participants; low-certainty evidence) and may increase AHI (MD 10.50 points, 95% CI 3.43 to 17.57; one study, 49 participants; low-certainty evidence). Compared to respiratory exercises plus nasal dilator strip, myofunctional therapy may result in little to no difference in daytime sleepiness (MD 0.20 points, 95% CI -2.46 to 2.86; one study, 58 participants; low-certainty evidence); probably increases sleep quality slightly (-1.94 points, 95% CI -3.17 to -0.72; two studies, 97 participants; moderate-certainty evidence); and may result in little to no difference in AHI (MD -3.80 points, 95% CI -9.05 to 1.45; one study, 58 participants; low-certainty evidence). Compared to standard medical treatment, myofunctional therapy may reduce daytime sleepiness (MD -6.40 points, 95% CI -9.82 to -2.98; one study, 26 participants; low-certainty evidence) and may increase sleep quality (MD -3.10 points, 95% CI -5.12 to -1.08; one study, 26 participants; low-certainty evidence). In children, compared to nasal washing alone, myofunctional therapy and nasal washing may result in little to no difference in AHI (MD 3.00, 95% CI -0.26 to 6.26; one study, 13 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Compared to sham therapy, myofunctional therapy probably reduces daytime sleepiness and may increase sleep quality in the short term. The certainty of the evidence for all comparisons ranges from moderate to very low, mainly due to lack of blinding of the assessors of subjective outcomes, incomplete outcome data and imprecision. More studies are needed. In future studies, outcome assessors should be blinded. New trials should recruit more participants, including more women and children, and have longer treatment and follow-up periods.

Sonographic Assessment of Oropharynx Movement During Deep Breathing

To investigate the feasibility of ultrasonography in detecting the oropharynx movement during deep breathing and to quantitatively analyze oropharynx airway lumen changes during deep breathing. The motions of oropharynx were monitored, and sonographic measurements of airway lumen were obtained during deep breathing in 448 healthy volunteers. Adequate visualization of oropharynx movement was obtained on all healthy volunteers. The anterior-posterior (AP) diameters and AP/transverse (T) diameter ratios were greater at the end of deep inspiration than that at the end of deep expiration for each sex (p < 0.01). The anterior-posterior dimensional changes were greater than lateral airway dimensional changes each sex (p < 0.05). Ultrasonography could provide realistic impression of the process on the oropharynx movement during deep breathing and perform the quantitative analysis of the oropharynx airway lumen changes during deep breathing. The results were encouraging and supported the utility of ultrasonography in future studies.

Differential Response Pattern of Oropharyngeal Pressure by Bolus and Dry Swallows

The aim of this study was to determine if bolus and dry swallow showed similar pressure changes in the oropharynx using our newly developed device. A unique character of it includes that baropressure can be measured with the sensor being placed in the balloon and can assess the swallowing mechanics in terms of pressure changes in the oropharynx with less influences of direct contacts of boluses and oropharyngeal structures during swallow indirectly. Fifteen healthy subjects swallowed saliva (dry), 15 ml of water, 45 ml of water, and 15 ml of two different types of food in terms of viscosity (potage soup-type and mayonnaise-type foods). Suprahyoid muscle activity was recorded simultaneously. Three parameters, area under the curve (AUC), peak amplitude, and duration of pressure, were analyzed from each swallow. Almost all of the bolus swallowing events had biphasic baropressure responses consisting of an early phase and late phase (99%), whereas 90% of the saliva swallowing events had a single phase. AUC, peak, and duration displayed greater effects during the late phase than during the early phase. Baropressure of the early phase, but not of the late phase, significantly increased with increasing volume; however, small but significant viscosity effects on pressure were seen during both phases. Peak pressure of the late phase was preceded by maximum muscle activity, whereas that of the early phase was seen when muscle activity displayed a peak response. These findings indicated that our device with the ability to measure baropressure has the potential to provide additional parameter to assess the swallow physiology, and biphasic baropressure responses in the early and late phases could reflect functional aspects of the swallowing reflexes.

Neural Transmission from Oropharyngeal Bitter Receptors to the Medulla is Partially or Completely Labelled-Line

The ground breaking advances in taste cell receptor cell physiology over the last 20 years have established a functional basis which enables neural pathways to be mapped. There is.only one, or perhaps several, types of taste receptors for salt, sour, sweet and umami (meaty) tastes and stimulation of each receptor type elicits responses in different cognitive regions. These findings support the labelled-line neural pathway model. In contrast, there are 25 types of the bitter taste receptors which all produce the same cognitive sensation, a finding which supports the across-fiber pattern model. This paper compiles the findings.of several human studies investigating the impact of bitter tastants on postprandial hemodynamics, to demonstrate that diverse bitter tastants are capable of eliciting a range of characteristic reflex cephalic phase responses in the autonomic and cardiovascular systems. These findings indicate that neural pathways from the oropharyngeal bitter taste receptors to the nucleus of the solitary tract are either partially or completely labelled-line. Consequently, the hedonics of a bitter tastant are not an accurate indicator of the cephalic phase responses elicited by the tastant. The finding that secondary metabolites present in dietary condiments modulate autonomic activity and in particular postprandial hemodynamics is novel and adds a new dimension to our understanding of the ways in which humans are influenced by their diet, both in health and disease. These findings suggest that condiments play a role in food digestion, unrelated to their. hedonistic qualities. Consequently, condiments may be of significance to those with digestive disorders and especially for diabetics experiencing gastroparesis and/or postprandial hypotension. Additionally, the findings suggest a noninvasive method to assess the integrity of multiple neural pathways. For investigators exploring the effect of condiments on autonomic reflexes, traditional cuisines may be a valuable source as they are full of uncharted human recordings.

Physiologic Model of Oropharyngeal Swallowing Revisited

Objective:

The purposes of this investigation were to determine whether the temporal onsets of swallow events segment into oral and pharyngeal phases, to test the interdependence of temporal onsets of swallow events, and to determine the influence of age on total swallow duration.

Study Design and Setting:

The onsets of swallowing and respiratory measures were studied in 76 healthy normal individuals.

Results:

Confirmatory factor analysis revealed a 2-factor solution but did not support the hypothesized 2-phase structure (ie, oral and pharyngeal). Two of the onsets, apnea onset and apnea offset, formed a single factor that explained 12.6% of the variation among the 11 onset times. The other 9 onsets formed a second factor that explained 66.4% of the variation. Age accounted for modest variation in total swallow duration.

Conclusions:

The two factors, oropharyngeal and respiratory, explained 79% of the variation among the 11 onset times.

Significance:

This finding speaks to the overlap between the initiation of oral and pharyngeal components of swallowing in adults and highlights the artificiality of separating the swallowing continuum into isolated phases.

Force and pressure distribution using Macintosh and GlideScope laryngoscopes in normal airway: an in vivo study

BACKGROUND

Forces applied on oropharyngeal soft tissues by direct laryngoscopy may cause damage to the patients. The aim of this study was to measure the forces applied during the manoeuvres to achieve glottis visualization and tracheal intubation, comparing direct laryngoscopy and videolaryngoscopy in vivo.

METHODS

Thirty adult patients (ASA physical status 1 or 2, BMI between 18 and 30 kg/m2, no difficulty to intubate) were randomly and blindly assigned to one of two groups. Forces and pressure distribution applied during glottis visualization and intubation were measured using film pressure transducers, comparing Macintosh direct laryngoscope and GlideScope videolaryngoscope.

RESULTS

Fifteen patients from each group, all with Cormack-Lehane grade 1 view, were analyzed. Forces applied during the intubation with the GlideScope were significantly lower than forces applied with the Macintosh (8+4 N vs. 40+14 N, respectively, P<0.001). Considering the Macintosh laryngoscope, the minimal force applied for glottis visualization was significantly lower than the one applied for intubation (16+6 N vs. 40+14 N, respectively, P<0.005). When using the Macintosh laryngoscope, forces were concentrated mostly on the tip, whereas with the GlideScope forces' concentration in a particular area was not observed.

CONCLUSION

Our study shows that in patients with normal airways the GlideScope allows a view of glottis and permits a successful tracheal intubation applying lower force (significantly in intubation) as compared to the Macintosh laryngoscope. Also, the GlideScope probe distributes the forces more homogeneously to the tissue thus further reducing the potential for tissue damage.

The oropharyngeal morphology in the semiaquatic giant Asian pond turtle, Heosemys grandis, and its evolutionary implications

The oropharynx as a functional entity plays a fundamental role in feeding. Transitions from aquatic to terrestrial lifestyles in vertebrates demanded major changes of the oropharynx for the required adaptations to a different feeding environment. Extant turtles evolved terrestrial feeding modes in three families (testudinids, emydids, geoemydids)-independently from other amniotes-and are therefore important model organisms to reconstruct morpho-functional changes behind aquatic-terrestrial transitions. In this study we hypothesized that the oropharyngeal morphology in semiaquatic turtles of the geoemydid family shows parallels to testudinids, the only purely terrestrial extant lineage. We provide an in-depth description of the oropharynx in the semiaquatic geoemydid Heosemys grandis by using a combination of micro computed tomography (micro-CT) and subsequent digital in situ 3-D reconstruction, scanning electron microscopy (SEM), and histology. We show that H. grandis has a large tongue with rough papillose surface and well-developed lingual muscles. The attachment sites of the lingual muscles on the hyolingual skeleton and their courses within the tongue are nearly identical with testudinids. The hyolingual skeleton itself is mainly cartilaginous and shows distinct-but compared to testudinids rather small-anterior extensions of the hyoid body and hypoglossum. Oral glands are well developed in H. grandis but are smaller and simpler than in testudinids. Similarly, oropharyngeal keratinization was minimal and found only in the anterior palate, regions close to the beak, and tongue tip. We conclude that H. grandis shows distinct oropharyngeal morpho-functional adaptations for a terrestrial lifestyle but still retains characters typical for aquatic forms. This makes this species an important example showing the oropharyngeal adaptations behind aquatic-terrestrial transitions in turtles.

Structure and topographic distribution of oral denticles in elasmobranch fishes

The placoid scales, or denticles, of the external epidermis of elasmobranchs are well known as a hard protective coat over the skin to reduce abrasion or as elements to reduce hydrodynamic drag. However, the structure and function of denticles within the oral cavity is uncertain. Using stereological and scanning electron microscopy, this study examines the structure and distribution of oral denticles in a range of elasmobranchs. Of the batoids analyzed, only members of the Rhinobatidae possessed oral denticles, with no denticles found in the members sampled in the Gymnuridae or Dasyatidae. In contrast, oral denticles were located in all the selachians examined, except for members of the Orectolobidae. Within the selachians, the denticles of the Carcharhinidae have a grooved surface and a central spine, which is angled toward the posterior of the mouth. These denticular adaptations are beneficial to reduce hydrodynamic drag, an advantage for these free-swimming species with ram ventilation. Alternatively, members of the Hemiscyllidae have broad bulbous denticles that often overlap, providing a hard surface to protect the epithelium from abrasion during the consumption of hard-bodied prey. The distribution and high number of oral denticles appears to spatially compromise the capacity for oral (taste) papillae to populate the oropharyngeal cavity but provides increased friction and grip on prey items as they are manipulated within the mouth.

Teledynamic evaluation of oropharyngeal swallowing

PURPOSE

The objective of the present investigation was to test the feasibility and clinical utility of a real-time Internet-based protocol for remote, telefluoroscopic evaluation of oropharyngeal swallowing.

METHOD

In this prospective cohort study, the authors evaluated 32 patients with a primary diagnosis of stroke or head/neck cancer. All patients participated in 2 separate fluoroscopic swallowing evaluations--one traditional on site and one telefluoroscopic off site--through the use of a telemedicine system. Agreement between sites was tested for 3 categories of variables: (a) overall severity of swallowing difficulty, (b) presence and extent of laryngeal penetration and aspiration as rated by the 8-point Penetration-Aspiration scale, and (c) treatment recommendations.

RESULTS

Results showed overall good agreement in subjective severity ratings (κ = 0.636) and in Penetration-Aspiration scale ratings (mean absolute difference = 1.1 points) between the onsite and offsite clinicians. Agreement in treatment recommendations was moderate to high, ranging from 69.3% to 100%.

CONCLUSIONS

The present study supports the feasibility and clinical utility of a telemedicine system for evaluating oropharyngeal swallowing. Given the difficulty and expertise needed to complete such evaluations, this study offers promising clinical avenues for patients in rural, remote, and underserved communities and countries where expert swallowing specialists are not available.

A critical evaluation of gestural stiffness estimations in speech production based on a linear second-order model

PURPOSE

Linear second-order models have often been used to investigate properties of speech production. However, these models are inaccurate approximations of the speech apparatus. This study aims at assessing how reliably stiffness can be estimated from kinematics with these models.

METHOD

Articulatory movements were collected for 9 speakers of German during the production of reiterant CVCV words at varying speech rates. Velocity peaks, movement amplitudes, and gesture durations were measured. In the context of an undamped model, 2 stiffness estimations were compared that should theoretically yield the same result. In the context of a damped model, gestural stiffness and damping were calculated for each gesture.

RESULTS

Numerous cases were found in which stiffness estimations based on the undamped model contradicted each other. Less than 80% of the data were found to be compatible with the properties of the damped model. Stiffness tends to decrease with gestural duration. However, it is associated with a large, unrealistic damping dispersion, making stiffness estimations from kinematic data to a large extent unreliable.

CONCLUSION

Any conclusions about speech control based on stiffness estimations using linear second-order models should therefore be considered with caution.

Pharyngeal pressure generation during tongue-hold swallows across age groups

PURPOSE

To compare the effects of the tongue-hold swallowing maneuver on pharyngeal pressure generation in healthy young and elderly research volunteers.

METHOD

Sixty-eight healthy research volunteers (young, n = 34, mean age = 26.8 years, SD = 5.5; elderly, n = 34, mean age = 72.6 years, SD = 4.8; sex equally represented) performed 5 noneffortful saliva swallows and 5 tongue-hold swallows each. Amplitude and duration of pharyngeal pressure were investigated during both swallowing conditions with solid-state pharyngeal manometry at the level of the oropharynx, hypopharynx, and upper esophageal sphincter (UES).

RESULTS

At both pharyngeal levels, tongue-hold swallows produced lower peak pressure compared with saliva swallows. During tongue-hold swallows, UES relaxation pressure was increased in the elders, whereas the younger group displayed a trend toward reduced relaxation pressure. Elderly individuals produced pressure longer during control swallows in the oropharynx and hypopharynx than young individuals.

CONCLUSIONS

The tongue-hold maneuver affects oropharyngeal and hypopharyngeal pressure in the young and elders in similar ways, whereas effects on UES peak relaxation pressure differ between age groups. Reduced pharyngeal peak pressure and increased UES relaxation pressure underscore the notion that tongue-hold swallows should not be performed when bolus is present. Long-term training effects remain to be investigated.

Morpho-functional patterns of physiologic oropharyngeal swallowing evaluated with dynamic fast MRI

With the advent of dynamic fast MRI sequences the act of deglutition can be dynamically visualized in cine-mode. Twenty-three healthy volunteers were enrolled in this study to define the morpho-functional patterns of oral and pharyngeal deglutition using new dynamic MRI techniques. All subjects were previously submitted to video endoscopic assessment, to exclude swallowing abnormalities. As contrast material a combination of yogurt mixed with gadolinium-diethylene diamine pentaacetic acid was used. The protocol was divided into three parts: (a) preliminary assessment of the oral cavity, pharynx and laryngeal structures; (b) morphologic assessment of tongue, soft palate, pharynx, epiglottis and larynx-hyoid bone; (c) dynamic assessment of swallowing without administrating any contrast media and, in subsequent phase, by injecting 5 ml of yogurt-based contrast medium in the patient's mouth. The time resolution was 3-4 images/s. The MR protocol revealed to be effective in the evaluation of normal motility patterns of the structures involved in swallowing. Moreover, the evaluation of the bolus progression, slowdown or stagnation, was possible. On the contrary problems were encountered in calculating precisely the bolus progression time, because of the insufficient temporal resolution. However, more energy should be invested to optimize the spatial and temporal resolution of turbo-FLASH sequences, to obtain a better dynamic representation of a complex function such as deglutition.

Evaluation of tongue-, jaw-, and swallowing-related muscle coordination during voluntarily triggered swallowing

PURPOSE

The prosthodontic treatment of dysphagic patients may preclude favorable treatment outcomes due to uncoordinated or discordant oral and pharyngeal functions. Since optimal treatment requires a full understanding of the mechanism of oropharyngeal swallowing, this study seeks to describe the normal temporal pattern of tongue-, jaw-, and swallowing-related muscle coordination during voluntarily triggered swallows in healthy patients.

MATERIALS AND METHODS

Tongue pressure against the hard palate at seven measuring points, swallowing sounds, and surface electromyography (EMG) activity of the masseter, anterior digastric, and infrahyoid muscles during voluntarily triggered swallowing were recorded in seven healthy male volunteers. The order of onset and offset of these parameters was analyzed by repeated-measures two-way analysis of variance.

RESULTS

The onset of anterior digastric muscle activity occurred first and was significantly earlier than the onset of the masseter or infrahyoid muscles and tongue pressure. The onset of masseter muscle activity was also significantly earlier than that of the infrahyoid muscle and tongue pressure. Offset of masseter activity was almost simultaneous with the swallowing sound and was significantly earlier than the offset of the anterior digastric and infrahyoid muscles as well as tongue pressure. The EMG burst of the anterior digastric muscle continued until the offset of tongue pressure, and was followed by the offset of infrahyoid muscle activity.

CONCLUSIONS

The temporal coordination patterns of the tongue, jaw, and oropharyngeal muscles during voluntarily triggered swallowing appear to agree with known safe management of a bolus and offer criteria for evaluating the function of oropharyngeal swallowing.

Evaluation of manometric measures during tongue-hold swallows

PURPOSE

Based on visual inspection, prior research documented increased movement of the posterior pharyngeal wall in healthy volunteers during tongue-hold swallows. This manometric study investigated the immediate effects of the tongue-hold maneuver on pharyngeal peak pressure generation, duration of pressure generation, and pressure slope measurements in healthy volunteers.

METHOD

Pharyngeal pressures from 40 young, healthy individuals (mean age = 25.8 years, gender equally distributed) were recorded at 3 locations: oropharynx, hypopharynx, and upper esophageal sphincter (UES), during normal control and tongue-hold swallows. Measures of peak amplitude, duration, and slope of pressure generation were subjected to statistical analysis.

RESULTS

Tongue-hold swallows produced lower pharyngeal peak pressure and shorter pharyngeal pressure durations compared to control swallows. Further, tongue-hold swallows produced lower UES relaxation pressures. Between sensors, peak pressure was lower and pressure slopes were steeper in the hypopharynx compared to the oropharynx. Several gender-specific differences were found for pharyngeal peak pressure, pressure duration, and pressure slopes.

CONCLUSIONS

Reduced amplitude and duration of pharyngeal peak pressure is likely a result of decreased base of tongue retraction during tongue-hold swallows. Central clinical considerations and future research directions are discussed in this article.

Evaluating oral stimulation as a treatment for dysphagia after stroke

Deglutitive aspiration is common after stroke and can have devastating consequences. While the application of oral sensory stimulation as a treatment for dysphagia remains controversial, data from our laboratory have suggested that it may increase corticobulbar excitability, which in previous work was correlated with swallowing recovery after stroke. Our study assessed the effects of oral stimulation at the faucial pillar on measures of swallowing and aspiration in patients with dysphagic stroke. Swallowing was assessed before and 60 min after 0.2-Hz electrical or sham stimulation in 16 stroke patients (12 male, mean age = 73 +/- 12 years). Swallowing measures included laryngeal closure (initiation and duration) and pharyngeal transit time, taken from digitally acquired videofluoroscopy. Aspiration severity was assessed using a validated penetration-aspiration scale. Preintervention, the initiation of laryngeal closure, was delayed in both groups, occurring 0.66 +/- 0.17 s after the bolus arrived at the hypopharynx. The larynx was closed for 0.79 +/- 0.07 s and pharyngeal transit time was 0.94 +/- 0.06 s. Baseline swallowing measures and aspiration severity were similar between groups (stimulation: 24.9 +/- 3.01; sham: 24.9 +/- 3.3, p = 0.2). Compared with baseline, no change was observed in the speed of laryngeal elevation, pharyngeal transit time, or aspiration severity within subjects or between groups for either active or sham stimulation. Our study found no evidence for functional change in swallow physiology after faucial pillar stimulation in dysphagic stroke. Therefore, with the parameters used in this study, oral stimulation does not offer an effective treatment for poststroke patients.

Temporal sequence of swallow events during the oropharyngeal swallow

PURPOSE

To (a) identify and characterize the temporal relation of selected structural movements during the oropharyngeal swallow across participants, (b) determine whether patterns of movement could be identified, and (c) determine whether the temporal relations were affected by aging and bolus characteristics.

METHOD

Retrospective analysis of videofluoroscopic swallows of 100 normal participants (age range=22-92 years) was conducted. Two swallows each of 3-ml and 10-ml liquids and a 1-3-ml paste bolus were analyzed. The onset of a number of structural movements and bolus arrival points were compared against a single reference event: onset of upper esophageal sphincter (UES) opening.

RESULTS

Normal participants demonstrated predominant sequences in pharyngeal movement patterns with some variability. The use of voluntary swallow maneuvers by these normal participants accounted for some degree of this variability. Volume, consistency, and age all affected the temporal relation between onset of specific motor events relative to the onset of UES opening. Increasing bolus volume was associated with a shorter temporal difference between UES opening and onset of other pharyngeal movements. In contrast, a thicker bolus was associated with longer temporal differences. Younger participants generally demonstrated shorter temporal differences between events than did older participants.

CONCLUSION

Temporal relations between structural movements are not fixed but can be systematically affected by bolus characteristics and age.

A comparison of vocal tract perturbation patterns based on statistical and acoustic considerations

The purpose of this study was to investigate the relation between vocal tract deformation patterns obtained from statistical analyses of a set of area functions representative of a vowel repertoire, and the acoustic properties of a neutral vocal tract shape. Acoustic sensitivity functions were calculated for a mean area function based on seven different speakers. Specific linear combinations of the sensitivity functions corresponding to the first two formant frequencies were shown to possess essentially the same amplitude variation along the vocal tract length as the statistically derived deformation patterns reported in previous studies.

A planar finite element model of bolus containment in the oral cavity

As individuals age, one of the objective changes that occurs in the oropharyngeal swallow is the development of a delay between bolus entry into the pharynx and the initiation of airway protection mechanisms. For longer delays, this phenomenon is sometimes referred to as "premature spillage," and it has been suggested that such spillage, which is a risk factor for dysphagia, may be associated with pre-swallow lingual gestures, or "tongue pumping." The goal of the current study was to develop a simplified two-dimensional computational model of the oropharynx to simulate the containment of a Newtonian fluid bolus within the oral cavity in response to a given pattern of lingual gestures for different viscosities. An arbitrary Lagrangian-Eulerian simulation was performed using the commercial finite element software package, LS-Dyna. It was found that for a given lingual motion, higher viscosity Newtonian boluses, consistent with those offered therapeutically, were able to be contained within the simulated oral cavity while a lower viscosity bolus would be "spilled," suggesting a potential mechanisim by which thickened liquids may reduce aspiration. Although the current data must be validated with more realistic, three-dimensional geometric information and for a wider range of bolus rheologies, they represent an exciting first step towards realistic modeling of oropharyngeal bolus flow.

Oral and oropharyngeal perceptions of fluid viscosity across the age span

Research demonstrates that varying sensory input, including the characteristics of a bolus, changes swallow physiology. Altering the consistency of fluids is a common compensatory technique used in dysphagia management to facilitate change. However, it is not known what variations in viscosity can be perceived in the oral cavity or oropharynx or if age affects oral and oropharyngeal perceptions of fluid viscosity. This study aims to establish the ability of normal adults to perceive fluid viscosity in the oral cavity and oropharynx and to determine if, within this population, there are age-related changes in oral and oropharyngeal perceptions. Sensitivity was established by deriving the exponent for the psychophysical law for fluid viscosity in both the oral cavity and the oropharynx, using modulus-free magnitude estimation with Newtonian fluids of corn syrup and water. Sixty normal volunteers, aged 21-84 years, participated. Results indicate that the exponent for oral perception of fluid viscosity was 0.3298, while for oropharyngeal perception it was 0.3148. Viscosity perception deteriorates with increasing age. Men exhibited a more marked deterioration in sensitivity than women. This study contributes to the literature on oral and oropharyngeal perceptions and on aging. The results provide a basis for work with individuals with dysphagia.

Hyoid-bolus transit latencies in normal swallow

Pharyngeal swallow delay is frequently found in dysphagic patients and is thought to be a factor in a range of swallowing problems, including aspiration. Implicit in notions of swallow "delay" is a temporal interval between two events that is longer than normal. However, there appears to be little agreement about which referent events should be considered in determining delay. A number of pharyngeal bolus transit points and various pharyngeal gestures have been used in delays determined from fluoroscopic evidence, and other referents have been used in electromyographic and manometric studies of swallow. In this study latencies between the first movement of the hyoid and several pharyngeal bolus transit points were calculated from fluoroscopic swallow studies in normal nondysphagic adults. Means and standard deviations of these latencies are provided for a 3-cc and a 20-cc bolus and for both nonelderly and elderly adults. The data may be a useful resource for relating the specific latencies investigated to concepts of pharyngeal swallow delay, in particular, when assessing videofluoroscopic studies using a similar protocol.

Volitional control of food transport and bolus formation during feeding

When healthy individuals eat solid food, chewed food is usually transported to the oropharynx where it accumulates before swallowing (stage II transport). We tested the hypothesis that this transport process can be altered by volition. Eight healthy young subjects ate 8 g pieces of cookie with barium while movements were recorded with videofluorography. There were two trials for each subject, each with different instructions: 1) without command: to eat the cookie in his/her usual manner; 2) with command: to chew the cookie, give a signal when ready to swallow, and then swallow on command of the investigator. We measured the number of chewing cycles, the duration of each stage in the feeding sequence, and the position of the leading edge of the barium at time of command and at swallow onset. Sequence duration was longer with than without command (P=0.02), primarily because of an increase in the number of chewing cycles (P=0.02). The leading edge was typically higher in the foodway at the time of swallow onset with than without command (P=0.06). Under the command condition, stage II transport was delayed, and transport to the valleculae was inhibited. Volition alters swallow initiation in both the timing and location of the food bolus relative to the airway.

A comparison of the oropharyngeal leak pressure between the reusable Classic laryngeal mask airway and the single-use Soft Seal laryngeal mask airway

We tested the oropharyngeal leak pressure with the reusable laryngeal mask airway and the single-use Soft Seal laryngeal mask airway. These two types of laryngeal mask airway (LMA) have a similar design but the reusable LMA cuff is made from silicone whereas the Soft Seal LMA cuff is polyvinylchloride. Thirty-five healthy subjects were anaesthetized and paralyzed and the two types of Soft Seal LMA were compared in a blinded randomized cross-over trial. The oropharyngeal leak pressure was significantly higher with the Soft Seal than the reuable (21 +/- 7.6 and 16 +/- 6.7 cm H2O respectively, P = 0.002). However, in four subjects the oropharyngeal leak pressure was higher with the reusable by > 4 cm H2O. We concluded that the reusable LMA may provide a better seal in some individuals but that, on average, the Soft Seal provides a higher oropharyngeal leak pressure than the reusable LMA.

Application of magnetic resonance imaging movie to assess articulatory movement

OBJECTIVE

To introduce the technique of magnetic resonance imaging (MRI) movie and to propose its feasibility for investigating articulatory movement.

SUBJECTS

Five healthy adult females participated in the study.

METHODS

Dynamic changes in oropharyngeal structures were assessed with MRI movie during the articulation of a bilabial consonant.

RESULTS

Movements of the velum and tongue at a time resolution of 30 ms were complex at the tip of the tongue and the anterior part of the velum. These movements that were seen with a time resolution of 30 ms could not be interpolated or in any way derived from the results obtained with a time resolution of 120 ms.

CONCLUSION

The results suggest that MRI movie may be useful in the evaluation of articulation. It is important to reduce the time resolution to 30 ms to obtain images of articulators.

Spontaneous facial motility in infancy: a 3D kinematic analysis

Early spontaneous orofacial movements have rarely been studied experimentally, though the motor experiences gained from these behaviors may influence the development of motor skills emerging for speech. This investigation quantitatively describes developmental changes in silent, spontaneous lip and jaw movements from 1 to 12 months of age using optically based 3D motion capture technology. Twenty-nine typically developing infants at five ages (1, 5, 7, 9, and 12 months) were studied cross-sectionally. Infants exhibited spontaneous facial movements at all ages studied. Several age-related changes were detected in lip and jaw kinematics: the occurrence of spontaneous movements increased, movement speed increased, the duration of movement epochs decreased and movement coupling among different facial regions increased. Additionally, evidence for stereotypic movements was not strong. The present findings suggest that, during the first year of life, early spontaneous facial movements undergo significant developmental change in the direction of skill development for speech.

Sex differences in prenatal oral-motor function and development

The aim of this study was to investigate sex-related differences in the prenatal development of early oral, lingual, pharyngeal, and laryngeal motor activities. Sonographic images of oral-upper airway regions were observed in 85 healthy fetuses (43 males, 42 females; mean gestational age 24wks 3d [SD 0.69]; range 15-38wks). Biometric data on morphologic development and associated motor patterns were compared across second and third trimesters. Results showed that while males and females demonstrated statistically similar patterns of general physical growth (p>0.05), significant differences in development of specific lingual and pharyngeal structures were present (p<0.05). Significant differences were found for laryngeal and pharyngeal motor activity, and oral-lingual movements (p<0.05). Complex oral-motor and upper airway skills emerged earlier in females, suggesting a sex-specific trajectory of motor development. It was concluded that differential patterns of prenatal motor development may be important in defining sex-specific indices of oral skill maturation.

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

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

Oropharyngeal stimulation with air-pulse trains increases swallowing frequency in healthy adults

This study sought to determine whether air-pulse trains delivered to the peritonsillar area would facilitate swallowing in healthy subjects. Trains of unilateral or bilateral air pulses were delivered to the peritonsillar area via tubing embedded in a dental splint, while swallows were simultaneously identified from their associated laryngeal and respiratory movements. Results from four subjects indicated that oropharyngeal air-pulse stimulation evoked an irrepressible urge to swallow, followed by an overt swallow as verified by laryngeal and respiratory movements. Moreover, air-pulse stimulation was associated with a significant increase in swallowing frequency. Mean latency of swallowing following bilateral stimulation tended to be less than the latency of swallowing following unilateral stimulation. These findings in healthy adults suggest the possibility that oropharyngeal air-pulse stimulation may have clinical utility in dysphagic individuals.

Temporal Measurements of Pharyngeal Swallowing in Normal Populations

The purpose of this investigation was to examine the temporal differences among three measures of pharyngeal stage transition in 40 normal subjects. The measures were (1) Pharyngeal Delay Time (PDT), (2) Stage Transition Duration (STD), and (3) Delayed Pharyngeal Swallow (DPS). Results showed a significant difference between younger and older subjects for PDT and STD but not for DPS. No gender differences were observed. These data on normal subjects will be used for comparisons with stroke patients in future research.

Reproducibility of swallowing over time in healthy elderly adults

The purpose of this study was to evaluate the reproducibility of aspects of swallowing assessed over time by the Exeter Dysphagia Assessment Technique. Fourteen healthy elderly adults were assessed during the morning on four consecutive days. During day 1, the assessment was repeated ten times. During days 2, 3, and 4 the assessment was carried out once and at the same time of the day. This allowed the reproducibility of the data to be examined between sessions and between days. The results show that the reproducibility of data between sessions was moderate to very good for all of the items evaluated (median kappas = 0.56-0.82, ICCs = 0.7-0.8). Between-day reproducibility was also moderate to very good for nine of the variables measured (median kappas = 0.58-0.96, ICCs = 0.53-0.84) and poor for one (ICC = 0.15). We conclude that the majority of variables examined by the Exeter Dysphagia Assessment Technique are reliable when swallowing is assessed repeatedly and on different days.

The Effects of Intraoral Pressure Sensors on Normal Young and Old Swallowing Patterns

Lingual pressure generation plays a crucial role in oropharyngeal swallowing. To more discretely study the dynamic oropharyngeal system, a 3-bulb array of pressure sensors was designed with the Kay Elemetrics Corporation (Lincoln Park, NJ). The influence of the device upon normal swallowing mechanics and boluses representative of flow relative to age and bolus condition was the focus of this study. Twelve healthy adults in two age groups (31 +/- 5 years, 2 males and 4 females, and 78 +/- 7 years, 2 males and 4 females) participated. Each subject was instructed to swallow four boluses representative of conditions with and without three pressure sensors affixed to the hard palate. Post-swallow residue at four locations, Penetration/Aspiration Scale scores, and three bolus flow timing measures were assessed videofluoroscopically with respect to age and bolus condition. The only statistically significant influences attributable to the presence of the pressure sensors were slight increases in residue in the oral cavity and upper esophageal sphincter with some bolus consistencies, 8% more frequent trace penetration of the laryngeal vestibule predominantly with effortful swallowing, and variances in oral clearance duration. We conclude that the presence of the pressure sensors does not significantly alter normal swallowing patterns of healthy individuals.

Influences of Thermal and Gustatory Characteristics on Sensory and Motor Aspects of Swallowing

Two sets of experiments were conducted to examine the effects of two sensory modalities, temperature and taste, of foods on perceptual and motor aspects of swallowing in 20 young, healthy subjects (10 subjects for each experiment). A tasteless and odorless thickening agent was the basic testing material. The first experiment compared the swallowing of foods at four temperatures ranging from 5 degrees C to 50 degrees C. Food at 50 degrees C was more acceptable for swallowing than at 5 degrees C, 20 degrees C, or 35 degrees C. The suprahyoid muscles were less active during swallowing food at 50 degrees C compared with swallowing food at the other three temperatures. The second experiment compared foods with the five basic taste qualities (sweetness, saltiness, sourness, bitterness, and umami) with a tasteless food (dissolved in distilled water) to examine the influence of gustatory sensation. The sweet and tasteless foods were somewhat more acceptable for swallowing than the sour and bitter foods. However, none of the foods differentially altered the motor parameters of swallowing. Interactive influences of temperature and gustatory sensations of foods on swallowing are discussed.

Dilation of the oropharynx via selective stimulation of the hypoglossal nerve

The functional effects of selective hypoglossal nerve (HG) stimulation with a multi-contact peripheral nerve electrode were assessed using images of the upper airways and the tongue in anesthetized beagles. A biphasic pulse train of 50 Hz frequency and 2 s duration was applied through each one of the tripolar contact sets of the nerve electrode while the pharyngeal images were acquired into a computer. The stimulation current was limited to 20% above the activation threshold for maximum selectivity. The images showed that various contact sets could generate several different activation patterns of the tongue muscles resulting in medial and/or lateral dilation and closing of the airways at the tongue root. Some of these patterns translated into an increase in the oropharyngeal size while others did not have any effect. The pharyngeal sizes were not statistically different during stimulation either between the two different positions of the head (30 degrees and 60 degrees), or when the lateral contacts were compared with the medial ones. The contacts that had the least effect generated an average of 53 +/- 15% pharyngeal dilation relative to the best contacts, indicating that the results are marginally sensitive to the contact position around the HG nerve trunk. These results suggest that selective HG nerve stimulation can be a useful technique to produce multiple tongue activation patterns that can dilate the pharynx. This may in turn increase the size of the patient population who can benefit from HG nerve stimulation as a treatment method for obstructive sleep apnea.

Activation of XII motoneurons and premotor neurons during various oropharyngeal behaviors

Neural control of tongue muscles plays a crucial role in a broad range of oropharyngeal behaviors. Tongue movements must be rapidly and accurately adjusted in response to the demands of multiple complex motor tasks including licking/mastication, swallowing, vocalization, breathing and protective reflexes such as coughing. Yet, central mechanisms responsible for motor and premotor control of hypoglossal (XII) activity during these behaviors are still largely unknown. The aim of this article is to review the functional organization of the XII motor nucleus with particular emphasis on breathing, coughing and swallowing. Anatomical localization of XII premotor neurons is also considered. We discuss results concerned with multifunctional activity of medullary and pontine populations of XII premotor neurons, representing a single network that can be reconfigured to produce different oromotor response patterns. In this context, we introduce new data on swallowing-related activity of XII (and trigeminal) motoneurons, and finally suggest a prominent role for the pontine Kölliker-Fuse nucleus in the control of inspiratory-related activity of XII motoneurons supplying tongue protrusor and retrusor muscles.

Application of the ‘pull-off’ force method for measurement of surface tension of upper airway mucosal lining liquid

Upper airway luminal patency is influenced by a number of factors including: intraluminal air pressure, upper airway dilator muscle activity, surrounding extraluminal tissue pressure and surface tension acting within the liquid layer lining the upper airway. In this study we examine the performance characteristics for the 'pull-off' force method for measuring the surface tension (gamma) of liquids. This method is then used to examine the gamma of the liquid lining the oro-pharynx in awake human subjects. The gamma of UAL samples (approximately 0.2 microL) obtained from the posterior pharyngeal wall was quantified using the pull-off force technique in which gamma is measured as the force required to separate two curved silica discs bridged by the liquid sample. Pull-off force measurement was not influenced by sample volumes or under different temperature or humidity conditions. The coefficients of variation for repeated measurements using the pull-off force technique for the three standard liquids ranged from 1.2% to 5.6%. The pull-off method tended to give slightly lower values than the Wihelmy balance method with the mean difference being 2.4 +/- 1.8 mN m(-1). For the group, the gamma of saliva was 59.2 +/- 0.6 mN m(-1) (CV 4.9 +/- 0.9%) for five measurements of a single sample. There was no significant relationship between the measured gamma values for five subjects measured on five separate days and the day of collection of the sample for any of the subjects or the group as a whole (both p > 0.6). There was no significant difference (p = 0.53, ANOVA) between the gamma values for samples obtained from under the tongue (61.6 +/- 1.7 mN m(-1)), at the oral surface of the soft palate (56.1 +/- 3.2 mN m(-1)) and from the posterior oro-pharyngeal wall (58.1 +/- 2.4 mN m(-1)). The pull-off force method provides adequate reproducibility to be able to measure the gamma of UAL. In healthy humans the gamma of UAL is similar to that of saliva.

Why do we have a uvula?: literature review and a new theory

From ancient times up to the present day many different functions and conditions have been attributed to the uvula, many speculative and some with a more scientific basis. The uvula has been shown to have the ability to produce and secrete large quantities of thin saliva. A common complication of surgery involving removal of the uvula is pharyngeal dryness. We have observed that on phonation and swallowing the uvula swings back and forth in the oropharynx. We present a review of the literature on the uvula and propose a theory that the uvula bastes the throat and thereby helps keep it moist and well lubricated.

Dynamic change of the upper airway during inhalation via aerosol delivery devices

Although it is likely that the upper airway is a major factor in the large inter- and intra-subject variation in deposition of inhaled drug aerosols in the lung, data on the configuration of the upper airway during inhalation is sparse. We have developed a unique method, using magnetic resonance imaging, to reconstruct the upper airway in three dimensions during inhalation from aerosol devices used to deliver medication to patients with asthma, chronic obstructive pulmonary disease, and cystic fibrosis. Ten healthy adults were imaged while inhaling from a pressurized metered dose inhaler (pMDI), a spacer used with pMDI (spacer), and a high-resistance dry powder inhaler, the Turbuhaler (DPI). The mean cross-sectional area of the oropharyngeal region was significantly larger (Wilcoxon's signed-rank test with Bonferroni correction, p < 0.0167) when the DPI (281 [143] mm2, mean [SD]) was used compared to the spacer (205 [32] mm2, p = 0.016) or pMDI (152 [48] mm2, p = 0.013). Considerable variations in the cross-sectional areas of the oral cavity, oropharynx, and larynx were seen when compared to the upper trachea. The main cause for this was the varying position of the tongue during inhalation via the devices. Although differences were observed when comparing the total volume of the upper airway during inhalation via the DPI (70 [17] cm3) to the pMDI (56 [20] cm3, p = 0.037) or spacer (59 [12] cm3, p = 0.022), these did not reach significance. This study shows that there are very significant variations in the configuration of the upper airway when different devices are used for inhalation. These changes are likely to be produced by a number of factors, including tongue position, device airflow resistance, and patient effort.

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.

The laryngeal mask airway Unique versus the Soft Seal laryngeal mask: a randomized, crossover study in paralyzed, anesthetized patients

We tested the hypothesis that ease of insertion, oropharyngeal leak pressure, fiberoptic position, ease of ventilation, and mucosal trauma are different for the Soft Seal laryngeal mask airway (SSLM) and the laryngeal mask airway Unique (LMA-U). Ninety paralyzed, anesthetized adult patients (ASA I-II; 18-80 yr old) were studied. Both devices were inserted into each patient in random order. Oropharyngeal leak pressure and fiberoptic position were determined during cuff inflation from 0-40 mL in 10-mL increments and at an intracuff pressure of 60 cm H(2)O. Ease of ventilation was determined by controlling ventilation for 10 min at 8 and 12-mL/kg tidal volume and recording hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, peak airway pressure, and the presence or absence of gastric insufflation. Mucosal trauma was determined by examining the first randomized device for the presence of visible and occult blood. Insertion time was shorter (P = 0.0001) and fewer attempts were required (P = 0.005) for the LMA-U. There were no failed uses of either device. Oropharyngeal leak pressures were similar, but fiberoptic position was superior with the LMA-U (P < or = 0.0003). There were no differences in hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, or peak airway pressure at either tidal volume. Gastric insufflation was not detected in either group at either tidal volume. The frequency of visible (P = 0.009) and occult blood (P = 0.0001) was less with the LMA-U. We conclude that the LMA-U is superior to the SSLM in terms of ease of insertion, fiberoptic position, and mucosal trauma, but similar in terms of oropharyngeal leak pressure and ease of ventilation.

The role of animal models in understanding feeding behavior in infants

The common evolutionary history humans share with mammals provides us with a solid basis for understanding normal oropharyngeal anatomy and functions. Physiologically, feeding is a cycle of neurophysiologic activity, where sensory input travels to the CNS which sends motor signals out to the periphery. Research with animal models is valuable because it is possible to disrupt this cycle, and develop predictive models on the causal basis of deviation from normal. Based on work with animal models, normal mammalian infant feeding behavior consists of the tongue functioning as a pump. First, the tongue assists in acquisition of milk from the nipple into the oral cavity, and then it pumps milk from the oral cavity into the valleculae prior to the pharyngeal swallow. Starting with this basic model, feeding in infant pigs was manipulated to determine the impact of variation in sensory input on behavioral output. One set of experiments suggested that chemo- or liquid sensation, in the form of milk is necessary to elicit continuing rhythmic activity. However, the rates of rhythmic suckling are intrinsic to an animal, and variation in rate cannot be entrained. Another set showed that initiation of the swallow does not purely depend on the volume of milk delivered, but also on the sensory stimulation at the mouth. These results support the idea that feeding behavior involves complex sensory integration.

[Oropharyngeal dysphagia in patients with multiple sclerosis]

AIMS

The aim of this study is to evaluate the prevalence of the clinical and videofluoroscopic (VDF) symptoms of oropharyngeal dysphagia in patients with multiple sclerosis, and to describe its therapeutic management.

PATIENTS AND METHODS

We studied 23 patients suffering from multiple sclerosis to evaluate the characteristics of the disease, the VDF exploration of swallowing and therapeutic strategies. The VDF exploration enables us to define the VDF symptoms that assess the safety and efficiency of swallowing for the oral and pharyngeal phases. The therapeutic strategies include: changes in the characteristics of the diet, changes of posture and active manoeuvres.

RESULTS

The patients studied presented a mean EDSS score 7.4 (4-9). There were alterations in swallowing efficiency and/or safety in more than 80% of the patients. In 52% there was some change in the swallowing safety. 40% of them were silent aspirators. All these patients were fed orally without any complications, in 78% the volume of the bolus has been modified and changes have taken place in the consistency (thickening for liquids); in 43%, moreover, postural strategies were employed and active manoeuvres (supraglottic swallow) were introduced in 13% in order to improve swallowing safety.

CONCLUSIONS

There is a high prevalence of clinical and VDF symptoms of oropharyngeal dysphagia in patients with advanced multiple sclerosis. VDF enables us to diagnose the pathophysiological mechanism of aspiration and the existence of silent aspirators, and helps us to introduce specific therapeutic interventions for each patient, thereby achieving safe and efficient swallowing, while prolonging oral feeding.

Functional outcomes after free flap reconstruction of the upper aerodigestive tract

PURPOSE OF REVIEW

When the complex structures of the upper aerodigestive tract are disrupted after resection of head and neck tumors, an appropriate reconstructive option should be chosen in an attempt to regain maximum function. Reconstructions using microvascular free tissue transfer offer unparalleled flexibility, both in tissue composition and in placement. This article will examine functional outcomes after free flap reconstruction of the upper aerodigestive tract.

RECENT FINDINGS

With the maturation of free tissue transfer techniques, functional outcomes are being analyzed with increasing frequency. Recent reports show promising results for free flap reconstruction of oral cavity, oropharyngeal, and hypopharyngeal soft tissue defects, as well as for bony mandibular and maxillary defects.

SUMMARY

For both soft tissue and bony defects of the upper aerodigestive tract, microvascular free flaps provide good functional outcomes. In the future, randomized studies are needed to compare the functional outcomes of microvascular free flaps with those of other reconstructive options.

Influences of head positions and bite opening on collapsibility of the passive pharynx

A collapsible tube surrounded by soft material within a rigid box was proposed as a two-dimensional mechanical model for the pharyngeal airway. This model predicts that changes in the box size (pharyngeal bony enclosure size anatomically defined as cross-sectional area bounded by the inside edge of bony structures such as the mandible, maxilla, and spine, and being perpendicular to the airway) influence patency of the tube. We examined whether changes in the bony enclosure size either with head positioning or bite opening influence collapsibility of the pharyngeal airway. Static mechanical properties of the passive pharynx were evaluated in anesthetized, paralyzed patients with sleep-disordered breathing before and during neck extension with bite closure ( n = 11), neck flexion with bite closure ( n = 9), and neutral neck position with bite opening ( n = 11). Neck extension significantly increased maximum oropharyngeal airway size and decreased closing pressures of the velopharynx and oropharynx. Notably, neck extension significantly decreased compliance of the oropharyngeal airway wall. Neck flexion and bite opening decreased maximum oropharyngeal airway size and increased closing pressure of the velopharynx and oropharynx. Our results indicate the importance of neck and mandibular position for determining patency and collapsibility of the passive pharynx.

The Relationship between Wearing Complete Dentures and Swallowing Function in Elderly Individuals: a Videofluorographic Study

The role of complete dentures in masticatory function is well established, but their effect on swallowing has been little examined. This study investigated the effect of complete dentures on swallowing in the elderly. Lateral projection videofluorography (VF) was performed for nine healthy edentulous elderly volunteers (mean age 73.9 +/- 2.9 years) while they swallowed 8 ml of liquid and paste barium with and without complete dentures. A total of 35 VF records were analyzed for temporal and spatial measurements of oropharyngeal motion during swallowing. The tongue tip contacted the inside of the lip between the upper and lower alveolar ridges during swallowing without but not with complete dentures. The hyoid moved further upward (P = 0.002) during swallowing without dentures (liquid: 5.85 +/- 3.99 mm, paste: 6.41 +/- 5.25 mm) than with dentures (liquid: 3.70 +/- 4.57 mm, paste: 3.69 +/- 4.07 mm). The larynx moved further forward (P = 0.044) during swallowing without dentures (liquid: 6.39 +/- 2.58 mm, paste: 6.46 +/- 2.87 mm) than with dentures (liquid: 5.34 +/- 2.04 mm, paste: 5.93 +/- 1.50 mm). The timing of the movements of these structures was not affected by the presence of the dentures or bolus consistency. These results showed that the hyoid and larynx moved more in swallowing without than with complete dentures, perhaps because of tongue tip protrusion when not wearing dentures. These findings suggest that complete dentures have a significant effect on swallowing function as well as masticatory function in elderly individuals.

Pharyngeal mucosal pressures with the laryngeal tube airway versus ProSeal laryngeal mask airway

We tested the hypothesis that mucosal pressures are higher for the laryngeal tube airway trade mark than the ProSeal laryngeal mask airway. Fifteen fresh cadavers were studied. Microchip pressure sensors were attached to the laryngeal tube airway and ProSeal laryngeal mask airway at four similar anatomical locations (base of tongue, lateral pharynx, posterior pharynx and posterior hypopharynx) and three dissimilar locations (laryngeal tube airway trade mark, anterior and lateral hypopharynx; ProSeal laryngeal mask airway, pyriform fossa). The cuff volume (laryngeal tube airway, < or = 140 ml; ProSeal laryngeal mask airway, < or = 30 ml) was adjusted until the oropharyngeal leak pressure was 15 cm H2O and the mucosal pressures recorded. This was repeated at an oropharyngeal leak pressure of 20, 25 and 30 cm H2O. Mucosal pressures in the lateral pharynx were always similar. Mucosal pressures at the base of tongue and posterior pharynx were similar for the laryngeal tube airway and ProSeal laryngeal mask airway at 15 and 20 cm H2O, but were higher for the laryngeal tube airway at 25 cm H2O at 30 cm H2O. Mucosal pressures in the posterior hypopharynx were always higher for the laryngeal tube airway (all: p < 0.03). Mean mucosal pressures for the laryngeal tube airway ranged from 8-31, 2-13 and 15-41 cm H2O for the base of tongue, lateral pharynx and posterior pharynx (proximal cuff) respectively and 3-7, 3-7 and 7-18 cm H2O for the anterior, lateral and posterior hypopharynx (distal cuff) respectively. Mean mucosal pressures for the ProSeal laryngeal mask airway ranged from 6-23, 3-10, 8-25, 6-17 and 2-8 cm H2O for the base of tongue, lateral pharynx, posterior pharynx, pyriform fossa and posterior hypopharynx respectively. We conclude that mucosal pressures are higher for the laryngeal tube airway, particularly when oropharyngeal leak pressure greater than 25 cm H2O. This suggests that mucosal ischemic injury will be more common with the LTA than the PLMA.

Esophageal contractions and oropharyngeal and esophageal transits in patients with iron deficiency anemia

OBJECTIVE

Patients with iron deficiency may have reduced power of the pharyngeal muscle for bolus propulsion into the esophagus. We hypothesized that esophageal muscle is similarly impaired.

METHODS

We studied the oropharyngeal and esophageal transits and esophageal motility of 12 patients (11 women) aged 31-50 yr (median 36 yr) with iron deficiency anemia (serum iron less than 40 microg/dl) and 17 normal volunteers (16 women) aged 26-52 yr (median 37 yr) with serum iron greater than 60 microg/dl. The esophageal motility was studied by the manometric method, with continuous perfusion and 10 swallows of a 2-ml bolus of water alternated with 10 swallows of a 7-ml bolus; and the oropharyngeal and esophageal transits were studied by scintigraphy, with swallows of a 10-ml bolus for the study of oropharyngeal transit and of a 10-ml bolus for the study of esophageal transit. Motility and transit were studied in the supine position.

RESULTS

The amplitude, duration and area under the curve of contractions were lower in patients than in volunteers. There were no differences in peristaltic contraction velocity, lower esophageal sphincter pressure, and lower esophageal sphincter relaxation duration. There was no difference in oropharyngeal transit. In the esophagus the transit was slower in patients than in volunteers. The time needed by the scintigraphic activity to reach a peak in the proximal esophagus was longer in patients than in volunteers.

CONCLUSIONS

Iron deficiency may decrease esophageal contractions and impair esophageal transit.

Airway management using the intubating laryngeal mask airway for the morbidly obese patient

We studied the effectiveness of the intubating laryngeal mask airway (ILMA) in morbidly obese patients scheduled for bariatric surgery. We included 118 consecutive morbidly obese patients (body mass index, 45 +/- 5 kg/m(2)). After the induction of general anesthesia, the laryngeal view was classified by the first observer according to the method of Cormack and Lehane. The ILMA was then inserted, and the trachea was intubated through the ILMA by a second observer. The rate of successful tracheal intubation with ILMA was 96.3%. The success rate, the number of attempts, and the total duration of the procedure were not different among patients with low-grade (Cormack 1-2) and patients with high-grade (Cormack 3-4) laryngeal views. The time required for insertion of the ILMA was slightly longer in patients with high-grade laryngeal views. Failures of the technique were not explained by the experience of the practitioner or airway characteristics. No adverse effect related to the technique was reported. Results of this study suggest that using the ILMA provides an additional technique for airway management of morbidly obese patients.

IMPLICATIONS

The intubating laryngeal mask airway (ILMA) provides an additional technique for airway management of morbidly obese patients. The best choice of the primary technique (laryngoscopy or ILMA) for tracheal intubation of an adult obese patient remains to be determined.

Physiologic effects of open and closed tracheostomy tubes on the pharyngeal swallow

Studies linking aspiration and dysphagia to an open tracheostomy tube exemplify the possibility that the larynx may have an influence on oropharyngeal swallow function. Experiments addressing the effects of tracheostomy tube occlusion during the swallow have looked at the presence and severity of aspiration, but few have included measurements that capture the changes in swallowing physiology. Also, hypotheses for the importance of near-normal subglottic air pressure during the swallow have not been offered to date. As such, the aim of this study was to compare the depth of laryngeal penetration, bolus speed, and duration of pharyngeal muscle contraction during the swallow in individuals with tracheostomy tubes while their tubes were open and closed. The results of this series of experiments indicate that within the same tracheostomized patient, pharyngeal swallowing physiology is measurably different in the absence of subglottic air pressure (open tube) as compared to the closed tube condition.

Emergence of oropharyngeal, laryngeal and swallowing activity in the developing fetal upper aerodigestive tract: an ultrasound evaluation

The developing fetal upper aerodigestive system provides the structural support for respiratory and ingestive functions necessary to sustain life at birth. This study investigated prenatal development of upper aerodigestive anatomy and the association of emerging functions as predictors of postnatal feeding skills. Biometric measures of oral, lingual, pharyngeal and laryngeal structures were obtained in fetuses 15-38 weeks gestational age using a four-plane sonographic technique. Accompanying ingestive behaviors were tallied across development. The data from 62 healthy controls were compared to seven cases at risk for postnatal feeding and swallowing dysfunction (Type II Arnold Chiari Malformation, trisomy 18, polyhydramnios, intrauterine growth restriction, Brachmann-de Lange Syndrome). Significant (p<0.001) linear regressions occurred in pharyngeal and lingual growth across gestation while ingestive behavior such as suckling emerged in a sequence of basic to complex movement patterns. Jaw and lip movements progressed from simple mouth opening to repetitive open-close movements important for postnatal suckling. Lingual movements increased in complexity from simple forward thrusting and cupping to anterior-posterior motions necessary for successful suckling at term. Laryngeal movements varied from shallow flutter-like movements along the lumen to more complex and complete adduction-abduction patterns. Fetal swallowing primarily occurred in the presence of concomitant oral-facial stimulatory activity. Significant variations (p<0.01) in the form and function of the ingestive system occurred in comparisons of gestational age-matched controls to at-risk cases. We postulate that prenatal developmental indices of emerging aerodigestive skills may guide postnatal decisions for feeding readiness and, ultimately, advance the care of the premature, medically fragile neonate.

Sex differences in genioglossus muscle response to changes in pharyngeal resistance

The genioglossus (GG) muscle's response to partial oropharyngeal occlusion was studied in age-matched, healthy awake men (n = 16) and women (n = 15). A miniature balloon was placed in the retroglossal pharynx, and the GG's electromyographic (EMG) reflexive response was evaluated in different body postures. We assumed that inflating the pharyngeal balloon and changing the body posture from upright to supine would increase pharyngeal airway resistance. Our hypothesis was that the change in airway resistance would elicit a different response in the GG muscle depending on sex. Our results showed that GG activity during natural breathing was higher in women than in men. GG EMG activity did not change upon inflation of the balloon in women. In contrast, when the balloon was inflated in the men, the GG's basal activity increased (P <.01) in both the upright and the supine positions. Women appeared to show a higher GG baseline EMG activity during spontaneous breathing at rest, while men were more responsive to the partial occlusion of the pharyngeal airway.

Comparison of methods for determining cricopharyngeal intrabolus pressure in normal patients as possible indicator for cricopharyngeal myotomy

OBJECTIVE

We sought to compare methods for determining intrabolus cricopharyngeal pressure as a possible indicator for cricopharyngeal myotomy.

STUDY DESIGN

We determined multiple intrabolus pressures in the cricopharyngeal region of 20 normal volunteers, of whom 12 were 20 to 35 years old and 8 were older than 75 years. Data were collected using a commercially available manofluorography system and a 6-sensor unidirectional solid-state 2- x 4-mm catheter. Each subject underwent 5 5-mL and 5 10-mL liquid barium swallows. Data were analyzed, and young subjects were compared with old subjects.

RESULTS

The mean mid-bolus pressures in young subjects were 5.2 +/- 4.9 mm Hg and 7.2 +/- 6.5 mm Hg for the 5-mL and 10-mL swallows, respectively, and in older subjects, 10.8 +/- 8.8 mm Hg and 12.3 +/- 7.4 mm Hg. The mean gradient pressures across the 3-cm cricopharyngeal region in young subjects were 2.02 +/- 5.0 mm Hg, and -0.91 +/- 4.8 mm Hg for the 5-mL and 10-mL swallows, respectively, and for older subjects, 4.38 +/- 3.1 mm Hg and 2.82 +/- 3.4 mm Hg.

CONCLUSIONS

Cricopharyngeal intrabolus pressures were lower in young than in older subjects. The mid-bolus pressure and the gradient pressure across the cricopharyngeal region appeared to be the most consistent methods for evaluating intrabolus pressures.

SIGNIFICANCE

Intrabolus pressure anomalies in the cricopharyngeal region have been proposed as an indicator for selecting patients who would benefit from cricopharyngeal myotomy. The methods of determining intrabolus pressures vary, with resulting variations in recommendations.