Seiko Shibata

Chewing and food consistency: Effects on bolus transport and swallow initiation

Preswallow bolus formation usually occurs in the mouth for liquids and in the oropharynx for solid foods. We examined the effect of chewing on the relationship between bolus transport and swallow initiation. Fifteen healthy subjects were imaged with lateral projection videofluorography while eating liquids, solid foods, and a mixture of liquid and solid foods in upright and facedown postures. Videotapes were reviewed to measure the location of the leading edge of the barium at swallow initiation. Chewing and initial consistency each altered the relationship between food transport and swallow initiation. In particular, when chewing liquid (or consuming foods with both liquid and solid phases), a portion of the food commonly reached the hypopharynx well before swallow onset. This transport to the hypopharynx was highly dependent on gravity, but transport to the valleculae for chewed solid food was active, depending primarily on tongue-palate contact. Chewing appeared to reduce the effectiveness of the posterior tongue-palate seal, allowing oral contents to spill into the pharynx. Consuming two-phase foods with both solid and liquid phases may increase the risk of aspiration in dysphagic individuals with impaired airway protective reflexes.

Dynamic change in hyoid muscle length associated with trajectory of hyoid bone during swallowing: analysis using 320-row area detector computed tomography

Research on muscle activation patterns during swallowing has been limited. Newly developed 320-row area detector computed tomography (320-ADCT) has excellent spatial and temporal resolution, which facilitates identification of laryngopharyngeal structures and quantitative kinematic analysis of pharyngeal swallowing. We investigated muscle activity patterns by observing the changes in length of hyoid muscles. 320-ADCT was performed in 26 healthy males while swallowing. The following parameters were analyzed three-dimensionally: 1) origins and insertions of the stylohyoid, anterior and posterior digastric, mylohyoid, geniohyoid, and thyrohyoid muscles; and 2) movement of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles began to shorten simultaneously during the initial stage of swallowing. The shortening of these muscles occurred during the upward movement of the hyoid bone. Subsequently, the geniohyoid, thyrohyoid, and anterior digastric muscles began to shorten, synchronizing with the forward movement of the hyoid bone. A significant correlation was observed between the shortened muscle lengths of the stylohyoid, posterior digastric, and mylohyoid muscles and the upward movement of the hyoid bone (r = 0.45-0.65). A correlation was also observed between the shortened muscle length of the geniohyoid muscle and the forward movement of the hyoid bone (r = 0.61). In this study, the sequence of muscle activity during pharyngeal swallowing remained constant. Serial shortening of the hyoid muscles influenced the trajectory of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles initiated the swallowing reflex and contributed to upward movement of the hyoid bone. The geniohyoid is a key muscle in the forward movement of the hyoid bone.

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.

Delayed Pharyngeal Response in CHEW‐SWALLOW Does Not Increase Risk of Aspiration in Individuals with Stroke

To the Editor: Dysphagia after stroke is common, and the pharyngeal swallow delay is associated with risk of aspiration in drinking liquid, because the safety of swallowing is compromised. In daily meals, chewing solid food or eating solids and liquids, like soups, is usual. Chewed solid food may be transported to the pharynx (stage II transport) up to 10 seconds before swallow onset in healthy subjects, whereas chewing a mixture of solid and liquid food has the highest risk of aspiration in individuals with dysphagia. However, to the best of the knowledge of the authors of this letter, there are no reports examining pharyngeal swallow delay in chew-swallow. Thus, the aim of this study was to compare pharyngeal response time of individuals with stroke with and without aspiration in chew-swallow.

Hyoid Bone Movement at Rest by Peripheral Magnetic Stimulation of Suprahyoid Muscles in Normal Individuals: MAGNETIC STIMULATION OF SUPRAHYOID MUSCLES

Neuromuscular electrical stimulation has been widely used in patients with dysphagia. However, obtaining sufficient hyoid bone movement through surface electrodes seems difficult. The aim of this study was to evaluate hyoid bone movement at rest through peripheral magnetic stimulation of the suprahyoid muscles in normal individuals.

Effect of visual biofeedback to acquire supraglottic swallow in healthy individuals: A randomized-controlled trial

The aim of this study is to evaluate the effect of visual biofeedback therapy in acquiring supraglottic swallow (SGS) in a randomized-controlled trial with healthy individuals. Eighteen individuals (mean age, 26 years) who could not close or keep closed the vocal folds before and during the swallow in SGS were allocated randomly to either a visual biofeedback group (eight individuals) or a nonbiofeedback group (10 individuals). A videoendoscope was inserted intranasally and an SGS exercise, using 4 ml of green-colored water, was performed 30 times per day up to 5 days. When the participant failed to perform SGS, the result was provided only to the participants in the visual biofeedback group. The median length of time until acquiring SGS was 1.5 days in the visual biofeedback group and 3.5 days in the nonbiofeedback group (P=0.040). We concluded that visual biofeedback effectively enabled participants to acquire SGS earlier.

Overview of Structures and Essential Terms

This chapter discusses common dysphagia terminology. A common understanding of important terms relevant to dysphagia enables healthcare professionals to communicate clearly and rapidly. The basic knowledge of anatomical structures associated with swallowing is fundamental to understanding the whole swallow process including the evaluation and treatment of dysphagia.

Physiological Models of Swallowing

Swallowing is a complex activity in humans that involves coordinated activity of the mouth, pharynx, larynx, and esophagus. Thorough knowledge of these physiological processes is necessary to understand the complexity of swallowing and serves as an essential module for explaining the fundamental mechanisms that operate in swallowing activity. In addition, an understanding of the mechanism of swallowing allows us to formulate new questions that serve as the basis for experiments and detect specific problems that must be managed in the clinical setting. The swallowing sequence is divided into stages, each involving different food management behaviors. Two common models of drinking and eating are widely used.

Oral Hygiene Care

People with dysphagia are at a greater risk of poor oral hygiene and health. Dried secretion accumulated in oral cavity reduces oral sensitivity and promote bacterial growth. Aspiration of these pathogens can lead to life-threatening respiratory disorders and pulmonary infection. Oral care is therefore important issue from the perspective of preventing aspiration pneumonia and swallowing rehabilitation in dysphagic patients.

Other Swallowing Treatments

In addition to several methods of swallowing exercise widely used to improve swallowing function, the alternative treatment by using assistive device and surgical intervention are viable options to achieve the treatment outcome, for safety and for improved quality of life. The common devices and surgical techniques commonly used in our practice are described in this chapter.