The effect of bolus viscosity on laryngeal closure in swallowing: kinematic analysis using 320-row area detector CT.

The present study examined the effect of bolus viscosity on the onset of laryngeal closure (relative to hyoid elevation), the duration of laryngeal closure, and other key events of swallowing in ten healthy volunteers. All volunteers underwent 320-row area detector computed tomography swallow studies while swallowing 10 ml of honey-thick barium (5 % v/w) and thin barium (5 % v/w) in a 45° reclining position. Three-dimensional images of both consistencies were created in 29 phases at an interval of 0.10 s (100 ms) over a 2.90-s duration. The timing of the motions of the hyoid bone, soft palate, and epiglottis; the opening and closing of the laryngeal vestibule, true vocal cords (TVC), and pharyngoesophageal segment; and the bolus movement were measured and compared between the two consistencies. The result showed differing patterns of bolus movement for thin and thick liquids. With thin liquids, the bolus reached the hypopharynx earlier and stayed in the hypopharynx longer than with thick liquids. Among events of laryngeal closure, only the timing of TVC closure differed significantly between the two consistencies. With thin liquids, TVC closure started earlier and lasted longer than with thick liquids. This TVC movement could reflect a response to the faster flow of thin liquids. The results suggest that bolus viscosity alters the temporal characteristics of swallowing, especially closure of the TVC.

Hyoid bone and larynx movements during electrical stimulation of motor points in laryngeal elevation muscles: a preliminary study.

OBJECTIVES: This study aimed to determine the laryngeal elevation muscle motor points, evaluate the movement of hyoid bone and larynx during stimulation of the motor points, and examine the potential for treating severe dysphagia by functional electrical stimulation. METHODS: The motor points of the laryngeal elevation muscles were anatomically determined from four cadavers. Those motor points in two healthy subjects and one lateral medullary syndrome patient were electrically stimulated by surface or implanted electrodes. RESULTS: The movements elicited by electrical stimulation of the motor points were greater in implanted than in surface electrodes. Elevation of the hyoid bone and the larynx in a lateral medullary syndrome patient were achieved with the implanted electrodes, but the upper esophageal sphincter opening was not obtained unless an additional cricopharyngeus muscle block was provided. CONCLUSION: The hyoid bone and larynx were elevated by electrically stimulating the motor points of the laryngeal elevation muscles.

Dysphagia associated with unilateral vocal cord immobility after cardiovascular surgery.

OBJECTIVE: Dysphagia associated with unilateral vocal cord immobility (UVCI) has received much less attention than did voice and phonation. The aim of this descriptive study was to evaluate the outcome of dysphagia associated with UVCI. DESIGN: Between June 2006 and September 2009, 69 hospitalized patients who underwent cardiovascular surgery were referred for dysphagia. Video endoscopic evaluation of swallowing was used for the detection of swallowing difficulties. Severity of dysphagia was assessed using the Dysphagia Severity Scale. RESULTS: Among the 69 patients, 31 UVCI patients who underwent video endoscopic evaluation of swallowing at least twice were used for analysis. All patients had severe to mild dysphagia at the first evaluation. Nineteen patients recovered from the UVCI at a mean follow-up of 125 days, whereas 12 had persistent UVCI at a mean follow-up of 216 days. Dysphagia Severity Scale at the first evaluation was not significantly different in both groups. At the last follow-up, the Dysphagia Severity Scale improved considerably without a significant difference in the magnitude of improvement in both groups. In the recovered and persistent UVCI groups, 16 and 7 patients, respectively, resumed their regular diets. CONCLUSIONS: Dysphagia associated with UVCI after surgery recovers, irrespective of the functional results of the UVCI.

Evaluation of swallowing using 320-detector-row multislice CT. Part I: single- and multiphase volume scanning for three-dimensional morphological and kinematic analysis.

A 320-detector-row multislice computed tomography (320-MSCT) scanner can acquire a volume data set covering a maximum range of 16 cm and can generate axial images 0.5-mm thick at 0.5-mm intervals. Three-dimensional (3D) images reconstructed from the thin axial slices include multiplanar reconstruction and 3D-CT. Single-phase 3D images are reconstructed from 0.175-s data, and multiphase 3D images are created in 29 phases at intervals of 0.1 s. Continuous replay of these 3D images produces four-dimensional moving images. In order to determine the feasibility of the morphologic and kinematic analyses of swallowing using 320-MSCT, single-phase volume scanning was performed on three patients and multiphase volume scanning was performed on one healthy volunteer. The single-phase 3D images clearly and accurately showed the structures involved in swallowing, and the multiphase 3D images were able to show the oral stage to the early esophageal stage of swallowing, allowing a kinematic analysis of swallowing. We developed a reclining chair that allows scanning to be performed with the subject in a semisitting position, which makes swallowing evaluation by 320-MSCT applicable not only to research on healthy swallowing but also to the clinical examination of dysphagia patients.

Evaluation of swallowing using 320-detector-row multislice CT. Part II: kinematic analysis of laryngeal closure during normal swallowing.

The purpose of this study was to (1) depict normal dynamic swallowing and (2) measure (a) the temporal characteristics of three components of laryngeal closure, i.e., true vocal cord (TVC) closure, closure of the laryngeal vestibule at the arytenoid to epiglottic base, and epiglottic inversion, and (b) the temporal relationship between these levels of laryngeal closure and other swallowing events, hyoid elevation, and the pharyngoesophageal segment (PES) using 320-detector-row multislice computed tomography (320-MSCT). The swallowing of a 10-ml portion of honey-thick liquid (5% w/v) was examined in six healthy volunteers placed in a 45° reclining position. Three-dimensional CT images were created in 29 phases at an interval of 0.10 s over a 2.90-s duration. Dynamic swallowing and TVC movement were depicted clearly. The sequence for laryngeal closure was the following: (1) the hyoid started to elevate, (2) the PES opened, (3) TVC closure and closure at the arytenoid to epiglottic base occurred almost simultaneously during the hyoid elevation, and (4) the epiglottic maximum inversion occurred after the hyoid maximum displacement. Those results indicated that the onset of hyoid elevation and the early opening of the PES occurring before three levels of laryngeal closure are critical components for airway protection. 320-MSCT allowed the 3D depiction and kinematic analysis of target structures, which will increase our knowledge of airway protection mechanisms during swallowing.

The risk of penetration or aspiration during videofluoroscopic examination of swallowing varies depending on food types.

Videofluoroscopic examination of swallowing (VF) is the gold standard in diagnosis and management of dysphagia. During VF, the patient ingests radiopaque foods and liquids, and oral, pharyngeal, and esophageal stages of swallowing physiology are observed and evaluated. Aspiration is defined as passage of materials through the vocal folds, and laryngeal penetration is defined as passage of materials into the larynx, but not through the vocal folds. In this study, we compared the risk of laryngeal penetration or aspiration during VF using various liquid volumes and food consistencies. Between January 2006 and September 2008, 229 patients with suspected dysphagia each were fed at least 2 out of 6 types of liquids or foods during VF in an upright posture without compensatory maneuvers. The 6 types were pudding-thick barium of 4 ml (PD), thin liquid barium of 4 ml (LQ4) and 10 ml (LQ10), one swallow of thin liquid barium from a cup (CUP), corned beef hash (8 g) with barium (CB), and a two-phase mixture of corned beef hash (4 g) with barium and thin liquid barium of 5 ml (MX). The paired comparisons revealed that laryngeal penetration risk increased in the following order: PD, CB, LQ4, LQ10, MX and CUP, while aspiration risk after PD increased in the following order: CB, LQ4, LQ10, CUP and MX. Thus, risk of laryngeal penetration or aspiration varies, depending on food types. In conclusion, risk of aspiration is highest with the two-phase food, and multi-textured foods should be used with caution in individuals with dysphagia.

Simple swallowing provocation test has limited applicability as a screening tool for detecting aspiration, silent aspiration, or penetration.

A number of tests for evaluating dysphagia without using videofluoroscopic examination of swallowing (VF) or videoendoscopic evaluation of swallowing (VE) have been developed. The simple swallowing provocation test (SSPT) is unique because it is performed while in a supine position and does not require the patient's cooperation. However, whether the SSPT detects aspiration or penetration correctly is unclear because its validity determined by VF or VE has not been evaluated. Therefore, we determined the sensitivity, specificity, and predictive accuracy of SSPT followed by VF in 45 patients. The sensitivities of the first-step and the second-step SSPT for the detection of aspiration, silent aspiration, or penetration were 72-75% and 13-17%, respectively; the specificities of the first-step and the second-step SSPT were 38-44% and 80-89%, respectively; and the predictive accuracies of the first-step and the second-step SSPT were 58-67% and 31-49%, respectively. These data suggest that SSPT has limited applicability as a screening tool for aspiration, silent aspiration, or penetration because of its low sensitivity. This test may be useful for patients who cannot undergo other tests due to cognitive and/or linguistic dysfunction.

Hyoid movement and laryngeal penetration during sequential swallowing.

This study examined hyoid movement during sequential swallowing and evaluated the relationship among trajectory patterns, swallowing types based on laryngeal movement and laryngeal penetration. Twelve healthy adults underwent videofluorography during sequential swallowing. Each swallow was classified into two types: opened laryngeal vestibule after swallow (i-Segmental type) and closed laryngeal vestibule after swallow (i-Continuous type). Each participant's swallowing type was classified by the same method. We analyzed two-dimensional movements of the hyoid, and the trajectories were classified into three patterns: hyoid moved in the anterosuperior direction after the onset of swallow (pattern L); hyoid moved in the anterosuperior direction after the onset of swallow, beyond the mandibular plane (pattern X); and the hyoid was above the mandibular plane at the onset of swallow, and then it moved in the inferior direction (pattern U). Two-way ANOVA revealed that there was a significant interaction between the swallowing type and trajectory pattern, and laryngeal penetration was the highest for the combination of individual swallow of i-Continuous type and pattern L. In sequential swallowing, the existence of a penetration-prone swallowing pattern combination was an interesting phenomenon relevant to eating management for dysphagic patients; however further study in patient groups is required.

Dysphagia rehabilitation in Japan.

This article describes the features of Japanese dysphagia rehabilitation, particularly where it differs from that in the United States. Many kinds of professionals participate in dysphagia rehabilitation; nurses and dental associates take important roles, and the Japanese insurance system covers that. Videofluorography and videoendoscopy are common and are sometimes done by dentists. Intermittent catheterization is applied to nutrition control in some cases. The balloon expansion method is applied to reduce pharyngeal residue after swallowing. If long-term rehabilitation does not work effectively in dysphagia due to brainstem disorder, the authors consider reconstructive surgery to improve function.

What is the chin-down posture? A questionnaire survey of speech language pathologists in Japan and the United States.

The "chin-down" or "chin-tuck" maneuver is a postural technique widely used in dysphagia treatment. The posture, however, does not have a precise anatomical definition. We studied the current practice of 42 speech-language pathologists (SLPs) in Japan and the U.S. with a questionnaire survey regarding the chin-down posture. The main findings were that (1) three of five of the pictures were selected by respondents both in Japan and in the U.S. as depicting the chin-down posture; (2) 23% of Japanese and 58% of the U.S. SLPs made a distinction between chin down and chin tuck; and (3) the use of anatomical terminology by SLPs differed between the two countries. This study showed that there is poor agreement among SLPs about the meaning of the chin-down and chin-tuck postures. Developing a precise definition is important because various postures may have differing physiologic effects.