Deglutitive laryngeal closure in stroke patients

Integrated non-invasive measurements reveal swallowing and respiration coordination recovery after unilateral stroke

BACKGROUND

Oropharyngeal dysphagia is common after a stroke. Understanding the physiology of swallowing and its coordination with respiration in stroke recovery is crucially important.

METHODS

A non-invasive swallowing assessment method was used to detect oropharyngeal swallowing and respiration coordination simultaneously during the swallowing process. This system detected movement of the larynx, submental muscle activity, and nasal airflow. Six different sizes of water boluses (maximum of 20 mL) were swallowed and assessed for each subject.

KEY RESULTS

We recruited 59 healthy participants and 38 first ever unilateral stroke patients completed baseline and follow-up assessments at 3, 6, and 9 months poststroke. The results showed that oropharyngeal swallowing parameters in unilateral stroke deviate from normal patterns. For respiration coordination, the unilateral stroke group had longer swallowing apnea duration but similar frequencies of pre- and postswallowing respiratory phase patterns compared with the healthy controls. The probability of piece-meal deglutition was higher in the stroke group than in the control group. Additionally, there were gradually decreasing piece-meal deglutition probabilities among the stroke patients at follow-up, and none differed statistically from those of the controls at 6 months poststroke.

CONCLUSIONS & INFERENCES

The non-invasive swallowing and respiration assessment method applied in this study detected the changes manifested in swallowing and respiration during the subacute phase of recovery in 6 months after a unilateral stroke. The study results serve as a baseline for further research and help advance dysphagia research methodologies. These assessments may be combined with bedside evaluations for clinical application.

Correlação entre tempo de trânsito oral e faríngeo no acidente vascular cerebral

Objetivo Correlacionar o tempo de trânsito oral total (TTOT) com o início da resposta faríngea (IRF) e o tempo de trânsito faríngeo (TTF) no indivíduo, após acidente vascular cerebral (AVC).Métodos O estudo incluiu 61 exames de videofluoroscopia de deglutição de indivíduos após AVC hemisférico isquêmico. Destes, 28 eram do gênero masculino e 33 do gênero feminino, com faixa etária variando de 40 a 101 anos (média de 65 anos). Para análise dos resultados, os indivíduos foram divididos em dois grupos. O Grupo 1 (G1) constou de 17 indivíduos com tempo de trânsito oral total até 2000 ms, conforme normalidade, e o Grupo 2 (G2), de 44 indivíduos com tempo de trânsito oral total maior que 2000 ms. Foi realizada análise quantitativa da deglutição orofaríngea. Cada indivíduo foi observado durante a deglutição de uma colher de 5 ml com alimento na consistência pastosa. Foi aplicado o teste de correlação de Spearman.Resultados Não houve correlação entre o G1 e a IRF e o TTF. Houve fraca correlação entre o G2 e os parâmetros estudados.Conclusão O aumento do tempo de trânsito oral total no indivíduo após AVC possui correlação fraca com o aumento do tempo na fase faríngea.

The Effect of Radiation Dose on Swallowing: Evaluation of Aspiration and Kinematics

Radiation oncologists have focused on the pharyngeal constrictors as the primary muscles of concern for dysphagia. However, our prior investigations have demonstrated that radiation dose to the geniohyoid rather than the constrictor muscles was more closely related to penetration aspiration scores (PAS). We examined the relationship between (1) radiation dose and swallowing temporal kinematics, and (2) between PAS and swallowing kinematics in these patients. Videofluoroscopic swallowing studies of 41 patients following radiation therapy for oropharyngeal cancer were analyzed for thin liquid boluses. Timing measures included duration of laryngeal vestibule closure (DLVC), duration to maximum hyoid elevation (DTMHE), duration to cricopharyngeal opening (DTCPO), and pharyngeal transit time (PTT). PAS was extracted for each swallow and considered normal if ≤ 2. As minimum and mean dose to the geniohyoid increased, DTMHE, DTCPO, and PTT increased. Worse PA scores were most strongly correlated with radiation dose received by geniohyoid (r = 0.445, p < 0.0001). Mean DLVC varied according to PAS group (normal PAS mean = 0.67 s, abnormal PAS mean = 0.13 s; p < 0.001). Similarly, DTCPO was significantly different based upon PAS (normal PAS mean = 0.22 s, abnormal PAS mean = 0.37 s, p = 0.016). As PAS increased, DTPCO and PTT increased (r = 0.208, p = 0.04; r = 0.204, p = 0.043). A negative correlation was noted between PAS and DLVC (r = -0.375, p = 0.001). Higher doses of radiation to the geniohyoid muscles are associated with increased severity of dysphagia as measured through both kinematics and PAS. Consideration of dose to the geniohyoid should be considered when planning radiation.

Compensatory recombination phenomena of neurological functions in central dysphagia patients

We speculate that cortical reactions evoked by swallowing activity may be abnormal in patients with central infarction with dysphagia. The present study aimed to detect functional imaging features of cerebral cortex in central dysphagia patients by using blood oxygen level-dependent functional magnetic resonance imaging techniques. The results showed that when normal controls swallowed, primary motor cortex (BA4), insula (BA13), premotor cortex (BA6/8), supramarginal gyrus (BA40), and anterior cingulate cortex (BA24/32) were activated, and that the size of the activated areas were larger in the left hemisphere compared with the right. In recurrent cerebral infarction patients with central dysphagia, BA4, BA13, BA40 and BA6/8 areas were activated, while the degree of activation in BA24/32 was decreased. Additionally, more areas were activated, including posterior cingulate cortex (BA23/31), visual association cortex (BA18/19), primary auditory cortex (BA41) and parahippocampal cortex (BA36). Somatosensory association cortex (BA7) and left cerebellum in patients with recurrent cerebral infarction with central dysphagia were also activated. Experimental findings suggest that the cerebral cortex has obvious hemisphere lateralization in response to swallowing, and patients with recurrent cerebral infarction with central dysphagia show compensatory recombination phenomena of neurological functions. In rehabilitative treatment, using the favorite food of patients can stimulate swallowing through visual, auditory, and other nerve conduction pathways, thus promoting compensatory recombination of the central cortex functions.

[Position paper of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery and the German Society of Phoniatrics and Pediatric Audiology - current state of clinical and endoscopic diagnostics, evaluation, and therapy of swallowing disorders in children and adults]

Position Paper of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery and the German Society of Phoniatrics and Pediatric Audiology - Current State of Clinical and Endoscopic Diagnostics, Evaluation, and Therapy of Swallowing Disorders in Children and AdultsSwallowing disorders are frequent. The main concern is mortality due to aspiration induced pneumonia and malnutrition. On the other hand quality of life is severely affected. The demographic trend indicates an increase of dysphagia in the future. Neurodegenerative diseases, tumors of the digestive tract and sequelae of tumor treatment in the head and neck region are the main pathologic entities.Predominantly ENT physicians and phoniatrists, are asked for diagnostics and therapy who will coordinate the interdisciplinary treatment according to the endoscopic findings.A differentiated approach in history, diagnostics, and symptom oriented treatment is necessary for the mostly complex disorders. The integration of non-medical personnel such as logopeds (speech language pathologists), physiotherapists, and occupational therapists in planning and executing an effective therapy expands and completes the patient-oriented care. Conservative treatment by these therapists is an important pillar in the treatment. Parts of the specific diagnostics can be taken over by them in close cooperation.In particular an interdisciplinary cooperation with the staff from intensive care medicine is indispensable.The diagnostic procedures of specific endoscopy as described in this position paper are part of the primary and fundamental tasks of ENT specialists and phoniatrists.Endoscopy is a medical service that is basically not delegable. Consequently substitution of the physician is precluded.

Mechanisms of airway protection during chin-down swallowing

PURPOSE

This study examined the effects of chin-down swallowing on laryngeal vestibule closure. It also investigated the technique's rehabilitative impact, by assessing the stability of effects across multiple trials and aftereffects in neutral swallows on cessation of the technique.

METHOD

Duration of laryngeal vestibule closure (dLVC) was measured with videofluoroscopy in 16 healthy participants (mean = 33.2 years, 9 men). Participants swallowed 40 times: 5 head-neutral swallows (N1), then 30 chin-down swallows, followed by 5 head-neutral swallows (N2). The first 5 chin-down swallows were categorized as early posture swallows (P1) and the last 5 as late posture swallows (P2). Within-participant comparisons determined the effects of the maneuver on dLVC during and after execution.

RESULTS

The study found that dLVC increased during chin-down swallows (N1 to P1, p = .018). This increase remained stable throughout 30 repetitions (P1 to P2, p = .994). On return to neutral, dLVC returned to baseline (N1 to N2, p = .875).

CONCLUSIONS

This study demonstrated increased dLVC during chin-down swallowing, offering a possible mechanism responsible for previously reported reduced aspiration during the technique. As aftereffects were not evident after multiple chin-down swallows, the maneuver appears to offer more compensatory benefit than rehabilitative value for patients with dysphagia.

Physiological factors related to aspiration risk: a systematic review

Penetration-aspiration is considered the most serious component of oropharyngeal dysphagia. Clinicians regularly evaluate the pathophysiology of swallowing and postulate reasons or mechanisms behind penetration-aspiration. In this article we share the results of a two-stage literature review designed to elucidate the association between abnormalities in physiological measures of swallowing function and the occurrence of penetration-aspiration. In the first stage, a broad scoping review was undertaken using search terms for nine different structures involved in oropharyngeal swallowing. In the second stage, based on the results of the initial search, a more focused systematic review was undertaken which explored the association between aspiration and abnormalities in respiratory, tongue, hyoid, and laryngeal function in swallowing. A total of 37 articles underwent detailed quality review and data extraction in the systematic review. The results support measurement of tongue strength, anatomically normalized measures of hyoid movement, bolus dwell time in the pharynx while the larynx remains open, respiratory rate, and respiratory swallow phasing as parameters relevant to aspiration risk.

The effects of feedback on volitional manipulation of airway protection during swallowing

Volitional control of autonomic responses, such as heart rate and blood pressure, can be facilitated with the use of augmented feedback. Oropharyngeal swallowing typically includes both volitional and reflexive components, offering a unique opportunity for observing how performance is affected by feedback. Sixteen healthy participants (M age=29 years, SD=10 years) completed multiple trials of a novel airway closure technique during swallowing under one of two conditions: no feedback or feedback. The feedback condition included knowledge of performance and knowledge of results. Only the feedback group improved performance across trials (p=.01), with no difference from baseline seen for the no feedback group (p=.66). These results show that airway closure during swallowing can be volitionally manipulated with augmented feedback.

Kinematic and temporal factors associated with penetration-aspiration in swallowing liquids

In this study we undertook careful analysis of 13 quantitative physiological variables related to oropharyngeal swallowing from a sample of 42 subacute patients referred for dysphagia assessment. Each patient underwent a videofluoroscopic swallowing examination in which they swallowed up to five boluses of 22 % w/v ultrathin liquid barium suspension administered by teaspoon. Our goal was to determine whether scores on 13 kinematic or temporal parameters of interest were independently associated with the presence of penetration-aspiration in the final compiled dataset of 178 swallows. Participants were classified as aspirators based on the presence of at least one swallow that demonstrated a Penetration-Aspiration Scale score of ≥3. The parameters of interest included six kinematic parameters for capturing hyoid position, three swallow durations [laryngeal closure duration, hyoid movement duration, and upper esophageal sphincter (UES) opening duration], and four swallow intervals (laryngeal closure to UES opening, bolus dwell time in the pharynx prior to laryngeal closure, stage transition duration, and pharyngeal transit time). Mixed-model repeated-measures ANOVAs were conducted to determine the association between each parameter and aspiration status. Only 1 of the 13 parameters tested distinguished aspirators from nonaspirators: aspirators demonstrated significantly shorter UES opening duration. In addition, a trend toward reduced maximum superior position of the hyoid was seen in aspirators. Limitations and future considerations are discussed.

Age-related changes of hyoid bone position in healthy older adults with aspiration

OBJECTIVES/HYPOTHESIS

Aspiration, the passage of a bolus below the vocal folds, increases morbidity and mortality in the elderly by increasing the risk of aspiration pneumonia and other conditions. We hypothesized that altered position of the hyoid bone associated with aging may negatively affect airway protection during swallowing (i.e., aspiration) in older adults.

STUDY DESIGN

Retrospective study.

METHODS

We re-reviewed computed tomography (CT) scans of the head from 40 older adults (65-80 years old), comprised of 20 aspirators and 20 nonaspirators, obtained from a previous cohort study. In addition, CT scans of the head from 40 young adults (20-40 years old) were retrieved from a medical records database. Three-dimensional reconstruction and 2-dimensional sagittal views were used to measure the distance between the mandible and hyoid bone. Comparisons between age groups, genders, and aspiration status were made.

RESULTS

Older adults had a larger distance between the hyoid and mandible in both latitude and longitudinal positions compared to the young adults. Among older males, there was evidence that the hyoid bone in the aspirators tended to be positioned more posterior compared to the nonaspirators.

CONCLUSIONS

The distance between the hyoid and mandible is increased with aging, and a more posterior position of the hyoid bone is correlated with aspiration in older males. These findings suggest that age-related changes in hyoid bone position may be a component of decreased swallowing safety and aspiration in older adults and warrant further investigation.

LEVEL OF EVIDENCE

N/A.

Post-stroke dysphagia: progress at last

Oropharyngeal Dysphagia (OD) is both underestimated and underdiagnosed as a cause of malnutrition and respiratory complications following stroke. OD occurs in more than 50% of stroke patients. Aspiration pneumonia (AP) occurs in up to 20% of acute stroke patients and is a major cause of mortality after discharge. Systematic screening for OD should be performed on every patient with stroke before starting oral feeding, followed, if appropriate by clinical and instrumental (videofluroscopy and/or fiberoptic endoscopy) assessment. Bolus modification with adaptation of texture and viscosity of solids and fluids and postural adjustments should be part of the minimal treatment protocol, but they do not change the impaired swallow physiology nor promote recovery of damaged neural swallow networks in stroke patients. To this purpose, two new neurostimulation approaches are being developed to stimulate cortical neuroplasticity to recover swallowing function: (i) those aimed at stimulating the peripheral oropharyngeal sensory system by chemical, physical or electrical stimulus; and (ii) those aimed at directly stimulating the pharyngeal motor cortex, such as repetitive transcranial magnetic stimulation (rTMS). The study of Park et al. in this issue of Neurogastroenterology and Motility evaluated the effect of rTMS in dysphagic stroke patients and showed a marked improvement in swallow physiology. Other studies also using rTMS showed plastic changes in pharyngeal motor cortical areas relevant to swallowing function. If further randomized controlled trials confirm these initial results, the neurorehabilitation strategies will be introduced to clinical practice sooner rather than later, improving the recovery of dysphagic stroke patients. Progress at last.

Timing differences between cued and noncued swallows in healthy young adults

Temporal parameters such as stage transition duration, bolus location at swallow onset, and pharyngeal transit time are often measured during videofluoroscopy, but these parameters may vary depending on assessment instructions. Specifically, "command" (cued) swallows have been observed to alter timing compared to spontaneous (noncued) situations in healthy older adults. The aim of our study was to confirm whether healthy young people show timing differences for thin liquid swallows between cued and noncued conditions. Twenty healthy young adults swallowed 10-cc boluses of ultrathin barium in videofluoroscopy. The cued condition was to hold the bolus in the mouth for 5 s before swallowing. Three noncued swallows were also recorded. In the cued condition, bolus advancement to the pyriform sinuses prior to swallow initiation was seen significantly less frequently. Stage transition durations showed a nonsignificant trend toward being shorter. Pharyngeal transit times and pharyngeal response time (a measure capturing the interval between hyoid movement onset and bolus clearance through the upper esophageal sphincter) were both significantly longer in the cued condition. Our study in healthy young adults confirms findings previously observed in older adults, namely, that swallow onset patterns and timing differ between cued and noncued conditions. In particular, bolus advancement to more distal locations in the pharynx at the time of swallow onset is seen more frequently in noncued conditions. This pattern should not be mistaken for impairment in swallow onset timing during swallowing assessment.

Unilateral superior laryngeal nerve lesion in an animal model of dysphagia and its effect on sucking and swallowing

We tested two hypotheses relating to the sensory deficit that follows a unilateral superior laryngeal nerve (SLN) lesion in an infant animal model. We hypothesized that it would result in (1) a higher incidence of aspiration and (2) temporal changes in sucking and swallowing. We ligated the right-side SLN in six 2-3-week-old female pigs. Using videofluoroscopy, we recorded swallows in the same pre- and post-lesion infant pigs. We analyzed the incidence of aspiration and the duration and latency of suck and swallow cycles. After unilateral SLN lesioning, the incidence of silent aspiration during swallowing increased from 0.7 to 41.5%. The durations of the suck containing the swallow, the suck immediately following the swallow, and the swallow itself were significantly longer in the post-lesion swallows, although the suck prior to the swallow was not different. The interval between the start of the suck containing a swallow and the subsequent epiglottal movement was longer in the post-lesion swallows. The number of sucks between swallows was significantly greater in post-lesion swallows compared to pre-lesion swallows. Unilateral SLN lesion increased the incidence of aspiration and changed the temporal relationships between sucking and swallowing. The longer transit time and the temporal coordinative dysfunction between suck and swallow cycles may contribute to aspiration. These results suggest that swallow dysfunction and silent aspiration are common and potentially overlooked sequelae of unilateral SLN injury. This validated animal model of aspiration has the potential for further dysphagia studies.

Sour taste and cold temperature in the oral phase of swallowing in patients after stroke

PURPOSE: To determine the effect of sour flavor and cold temperature on oral transit time during swallowing. METHODS: Participants were 52 subjects (28 male and 24 female) with ages between 50 and 80 years (median=66 years), after ischemic stroke involving right or left side damage and mild to moderate oropharyngeal dysphagia. Videofluoroscopy was performed to analyze the swallowing times. Each subject was assessed during swallowing of a paste consistency bolus offered in 5 ml spoons, with a total of four different stimuli (natural, cold, sour and sour-cold). After the exam, the oral transit time was measured using specific software. The oral transit time (starting at the beginning of the bolus movement in the mouth) and the total oral transit time (starting at the moment that the bolus is placed in the mouth) were measured. RESULTS: The association between sour and cold stimuli caused a significant decrease of oral transit time and total oral transit time. CONCLUSION: Sour flavor and cold temperature reduced oral transit time in stroke patients.

Videofluoroscopic assessment of pharyngeal stage delay reflects pathophysiology after brain infarction

OBJECTIVES/HYPOTHESIS

The pathophysiology of dysphagia caused by brain infarction varies with the site of the lesion in the brain. Patients with suprabulbar lesions have demonstrated delayed triggering of pharyngeal stage including delayed laryngeal elevation. Patients with severe pharyngeal stage delay have a high risk of intractable aspiration to the lower respiratory tract. Despite this, few studies have compared the pharyngeal stage delay with the lesion site. We defined a new temporal parameter of the pharyngeal stage delay to assess laryngeal elevation delay against the bolus inflow into the pharyngeal space. This study aimed to elucidate whether this parameter of pharyngeal stage delay is clinically useful to assess the pathophysiology of brain lesions after brain infarction.

STUDY DESIGN

Case-control study.

METHODS

Videofluoroscopic assessment of swallowing examinations was performed from January 7, 2000 to March 29, 2011 at Kyushu University Hospital. We evaluated the pharyngeal stage delay using motion analysis on videofluoroscopic swallowing examination in patients with normal swallowing and brain infarction patients divided into pathophysiologic lesion groups. Laryngeal elevation delay time and pharyngeal delay time were analyzed.

RESULTS

Significant differences in laryngeal elevation delay time were observed between each pathophysiologic lesion group. However, pharyngeal delay time remained similar among groups. Brain infarctions of corticobulbar tract and basal ganglion were significantly associated with laryngeal elevation delay time prolongation.

CONCLUSIONS

Laryngeal elevation delay time with low-viscosity contrast medium is a recommended parameter to discriminate the corticobulbar tract and the basal ganglion lesion.

The influence of sour taste on Dysphagia in brain injury: blind study

Objective

To verify the influence of sour taste on swallowing and the presence of reflex cough when sour material was swallowed in patients with dysphagia secondary to brain injury.

Method

Fifty dysphagic brain injury patients who underwent videofluoroscopic swallowing study (VFSS) were recruited. The patients who had shown severe aspiration at 2 ml of liquid were excluded. The dysphagic patients were given 5 ml each of a sour tasting liquid (SOUR) and a thin liquid barium (LIQUID) in random order. An expert analyzed the result of VFSS by reviewing recorded videotapes. Analysis components consisted of the Penetration-Aspiration-Scale (PAS) score, oral transit time (OTT), pharyngeal transit time (PTT), pharyngeal delay time (PDT) and the reflex cough presence.

Results

The PAS score for SOUR was significantly lower than the one for LIQUID (p=0.03). The mean OTT for SOUR was significantly shortened compared to that for LIQUID (p=0.03). The mean PTT and PDT were also shortened in SOUR, although the differences were not statistically significant (p=0.26 and p=0.32, respectively). There was no significant difference between SOUR and LIQUID regarding the presence of reflex cough (p=1.00).

Conclusion

The sour taste could enhance sensorimotor feedback in the oropharynx, thus lowering the chances of penetration-aspiration caused by shortening of the oropharyngeal passage times. There was no significant difference in the presence of reflex cough produced between LIQUID and SOUR.

The Effects of Bolus Consistency in Pharyngeal Transit Duration during Normal Swallowing

Objective

To examine the effects of age, gender and bolus consistency in normal populations using the temporal measurement of Pharyngeal Transit Duration (PTD), which reflects the duration of bolus flow from the ramus of the mandible to the upper esophageal sphincter.

Method

40 normal and healthy subjects had Videofluoroscopic Swallowing Examinations (VFSEs) of 5 ml thin and nectar thick liquids, and puree consistencies. A slow motion and frame by frame analysis was performed. Three-way analysis of variance (ANOVA) was performed to examine the main effect and interactions, and paired t-tests for the three consistency comparisons.

Results

Older subjects had a significantly longer PTD than younger subjects (p<0.01). In addition, men had significantly shorter PTDs than women (p<0.01). Puree showed a significantly longer PTD than the other two consistencies, regardless of age and gender (p<0.05).

Conclusion

PTD is an indicative of motor weakness in pharyngeal swallowing secondary to aging. In addition, the results supported the assumption that there is a functional difference in pharyngeal swallowing between men and women. It is expected that the results of this study will be used for further investigation of patients with dysphagia.

Temporal variability in the deglutition literature

A literature review was conducted on temporal measures of swallowing in healthy individuals with the purpose of determining the degree of variability present in such measures within the literature. A total of 46 studies that met inclusion criteria were reviewed. The definitions and descriptive statistics for all reported temporal parameters were compiled for meta-analysis. In total, 119 different temporal parameters were found in the literature. The three most-frequently occurring durational measures were upper esophageal sphincter opening, laryngeal closure, and hyoid movement. The three most-frequently occurring interval measures were stage transition duration, pharyngeal transit time, and duration from laryngeal closure-to-UES opening. Subtle variations in operational definitions across studies were noted, making the comparison of data challenging. Analysis of forest plots compiling descriptive statistical data (means and 95% confidence intervals) across studies revealed differing degrees of variability across durations and intervals. Two parameters (UES opening duration and the laryngeal closure-to-UES opening interval) demonstrated the least variability, reflected by small ranges for mean values and tight confidence intervals. Trends emerged for factors of bolus size and participant age for some variables. Other potential sources of variability are discussed.

A method to objectively assess swallow function in adults with suspected aspiration

BACKGROUND & AIMS

Pharyngeal manometry and impedance provide information on swallow function. We developed a new analysis approach for assessment of aspiration risk.

METHODS

We studied 20 patients (30-95 years old) with suspected aspiration who were referred for videofluoroscopy, along with controls (ages 24-47 years). The pharyngeal phase of liquid bolus swallowing was recorded with manometry and impedance. Data from the first swallow of a bolus and subsequent clearing swallows were analyzed. We scored fluoroscopic evidence of aspiration and investigated a range of computationally derived functional variables. Of these, 4 stood out as having high diagnostic value: peak pressure (PeakP), pressure at nadir impedance (PNadImp), time from nadir impedance to peak pressure (TNadImp-PeakP), and the interval of impedance drop in the distal pharynx (flow interval).

RESULTS

During 54 liquid, first swallows and 40 clearing swallows, aspiration was observed in 35 (13 patients). Compared to those of controls, patient swallows were characterized by a lower PeakP, higher PNadImp, longer flow interval, and shorter TNadImp-PeakP. A Swallow Risk Index (SRI), designed to identify dysfunctions associated with aspiration, was developed from iterative evaluations of variables. The average first swallow SRI correlated with the average aspiration score (r = 0.846, P < .00001 for Spearman Rank Correlation). An average SRI of 15, when used as a cutoff, predicted aspiration during fluoroscopy for this cohort (κ = 1.0).

CONCLUSIONS

Pressure-flow variables derived from automated analysis of combined manometric/impedance measurements provide valuable diagnostic information. When combined into an SRI, these measurements are a robust predictor of aspiration.

Automated anatomical demarcation using an active shape model for videofluoroscopic analysis in swallowing

The current gold standard method in the clinical assessment of swallowing is the visual inspection of videofluoroscopic frames. Specific clinical measurements are estimated based on various anatomical and bolus positional information with respect to time (or frame number). However, due to the subjective nature of visual inspection clinicians face intra- and inter-observer repeatability issues and bias when making these estimations. The correct demarcations of reference lines highlighting the positions of important anatomical landmarks would serve as a visual aid and could also be used in conjunction with bolus detection methods to objectively determine these desirable measurements. In this paper, we introduce and test the reliability of applying a 16-point Active Shape Model as a deformable template to demarcate the boundaries of salient anatomical boundaries with minimal user input. A robust end and corner point detection algorithm is also used to provide image information for the suggested movement of the template during the fitting stage. Results show the model deformation constraints calculated from a training set of images are clinically coherent. The Euclidean distances between the fitted model points against their corresponding target points were measured. Test images were taken from two different data sets from frames acquired using two different videofluoroscopy units. Overall, fitting was found to be more reliable on the vertebrae and inferior points of the larynx compared to the superior laryngeal points and hyoid bone, with the model always fitting the C7 vertebra with discrepancies no higher than a distance of 23 pixels (3.2% of the image width, approximately 7.6mm).

Coordination of Mastication, Swallowing and Breathing

The pathways for air and food cross in the pharynx. In breathing, air may flow through either the nose or the mouth, it always flows through the pharynx. During swallowing, the pharynx changes from an airway to a food channel. The pharynx is isolated from the nasal cavity and lower airway by velopharyngeal and laryngeal closure during the pharyngeal swallow. During mastication, the food bolus accumulates in the pharynx prior to swallow initiation. The structures in the oral cavity, pharynx and larynx serve multiple functions in breathing, speaking, mastication and swallowing. Thus, the fine temporal coordination of feeding among breathing, mastication and swallowing is essential to provide proper food nutrition and to prevent pulmonary aspiration. This review paper will review the temporo-spatial coordination of the movements of oral, pharyngeal, and laryngeal structures during mastication and swallowing, and temporal coordination between breathing, mastication, and swallowing.

Spatiotemporal visualizations for the measurement of oropharyngeal transit time from videofluoroscopy

Videofluoroscopy remains one of the mainstay methods for clinical swallowing assessment, yet its interpretation is both complex and subjective. This, in part, reflects the difficulties associated with estimation of bolus transit time through the oral and pharyngeal regions by visual inspection, and problems with consistent repeatability. This paper introduces a software-only framework that automatically determines the time taken for the bolus to cross 1-D anatomical landmarks representing the oral and pharyngeal region boundaries ( Fig. 1). The user-steered delineation algorithm live-wire and straight-line annotators are used to demarcate the landmark on a frame prior to the swallow action. The rate of change of intensity of the pixels in each landmark is used as the detection feature for bolus presence that can be visualized on a spatiotemporal plot. Artifacts introduced by head and neck movement are removed by updating the landmark coordinates using affine parameters optimized by a genetic-algorithm-based registration method. Heuristics are applied to the spatiotemporal plot to identify the frames during which the bolus passes the landmark. Correlation coefficients between three observers visually inspecting twenty-four 5-mL single swallow clips did not exceed 0.42. Yet the same measurements taken using this framework on the same clips had correlation coefficients exceeding 0.87.

Improvements in tongue strength and pressure-generation precision following a tongue-pressure training protocol in older individuals with dysphagia: three case reports

Dysphagia, or difficulty swallowing, often occurs secondary to conditions such as stroke, head injury or progressive disease, many of which increase in frequency with advancing age. Sarcopenia, the gradual loss of muscle bulk and strength, can place older individuals at greater risk for dysphagia. Data are reported for three older participants in a pilot trial of a tongue-pressure training therapy. During the experimental therapy protocol, participants performed isometric strength exercises for the tongue as well as tongue pressure accuracy tasks. Biofeedback was provided using the Iowa Oral Performance Instrument (IOPI), an instrument that measures tongue pressure. Treatment outcome measures show increased isometric tongue strength, improved tongue pressure generation accuracy, improved bolus control on videofluoroscopy, and improved functional dietary intake by mouth. These preliminary results indicate that, for these three adults with dysphagia, tongue-pressure training was beneficial for improving both instrumental and functional aspects of swallowing. The experimental treatment protocol holds promise as a rehabilitative tool for various dysphagia populations.

Poststroke dysphagia rehabilitation by repetitive transcranial magnetic stimulation: a noncontrolled pilot study

Poststroke dysphagia is frequent and significantly increases patient mortality. In two thirds of cases there is a spontaneous improvement in a few weeks, but in the other third, oropharyngeal dysphagia persists. Repetitive transcranial magnetic stimulation (rTMS) is known to excite or inhibit cortical neurons, depending on stimulation frequency. The aim of this noncontrolled pilot study was to assess the feasibility and the effects of 1-Hz rTMS, known to have an inhibitory effect, on poststroke dysphagia. Seven patients (3 females, age = 65 +/- 10 years), with poststroke dysphagia due to hemispheric or subhemispheric stroke more than 6 months earlier (56 +/- 50 months) diagnosed by videofluoroscopy, participated in the study. rTMS at 1 Hz was applied for 20 min per day every day for 5 days to the healthy hemisphere to decrease transcallosal inhibition. The evaluation was performed using the dysphagia handicap index and videofluoroscopy. The dysphagia handicap index demonstrated that the patients had mild oropharyngeal dysphagia. Initially, the score was 43 +/- 9 of a possible 120 which decreased to 30 +/- 7 (p < 0.05) after rTMS. After rTMS, there was an improvement of swallowing coordination, with a decrease in swallow reaction time for liquids (p = 0.0506) and paste (p < 0.01), although oral transit time, pharyngeal transit time, and laryngeal closure duration were not modified. Aspiration score significantly decreased for liquids (p < 0.05) and residue score decreased for paste (p < 0.05). This pilot study demonstrated that rTMS is feasible in poststroke dysphagia and improves swallowing coordination. Our results now need to be confirmed by a randomized controlled study with a larger patient population.

Accuracy of the volume-viscosity swallow test for clinical screening of oropharyngeal dysphagia and aspiration

AIMS

To determine the accuracy of the bedside volume-viscosity swallow test (V-VST) for clinical screening of impaired safety and efficacy of deglutition.

METHODS

We studied 85 patients with dysphagia and 12 healthy subjects. Series of 5-20 mL nectar (295.02 mPa.s), liquid (21.61 mPa.s) and pudding (3682.21 mPa.s) bolus were administered during the V-VST and videofluoroscopy. Cough, fall in oxygen saturation > or =3%, and voice changes were considered signs of impaired safety, and piecemeal deglutition and oropharyngeal residue, signs of impaired efficacy.

RESULTS

Videofluoroscopy showed patients had prolonged swallow response (> or =1064 ms); 52.1% had safe swallow at nectar, 32.9%, at liquid (p<0.05), and 80.6% at pudding viscosity (p<0.05); 29.4% had aspirations, and 45.8% oropharyngeal residue. The V-VST showed 83.7% sensitivity and 64.7% specificity for bolus penetration into the larynx and 100% sensitivity and 28.8% specificity for aspiration. Sensitivity of V-VST was 69.2% for residue, 88.4% for piecemeal deglutition, and 84.6% for identifying patients whose deglutition improved by enhancing bolus viscosity. Specificity was 80.6%, 87.5%, and 73.7%, respectively.

CONCLUSIONS

The V-VST is a sensitive clinical method to identify patients with dysphagia at risk for respiratory and nutritional complications, and patients whose deglutition could be improved by enhancing bolus viscosity. Patients with a positive test should undergo videofluoroscopy.