Michio Yokoyama

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.

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.

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.

Estimation of Benefit and Radiation Risk from Mass Chest Radiography

The benefits and radiation risks are estimated from a mass chest x-ray survey in present-day Japan. About 4,000 × 104 chest fluorographies were carried out in 1968: 44,447 cases of active pulmonary tuberculosis and a probable total of 758 curable cases of lung cancer were detected. However, 1.82 leukemias per year or about 46 leukemias and 7 incurable chest cancers in the forthcoming 25-year period are expected among this population. Also, 150 genetic deaths are estimated until the 10th generation.

Effects of Food Consistencies and Mastication on Bolus Transport and SwallowInitiation in Individuals with Hemispheric Stroke

Mastication and food consistency each affect the passage of food through the oral cavity and pharynx and its coordination with swallow initiation. Since hemispheric stroke may damage cortico-medullary neural pathways, we hypothesized that it could also alter the coordination of eating and swallowing. Using videofluorography, we studied 30 individuals with hemispheric stroke and 27 age-matched controls as they consumed liquid barium, corned beef hash, or a combination of liquid and solid (two-phase) food. We tracked the leading edge of the barium during feeding and at swallow onset in relation to occurrences of laryngeal penetration and aspiration. Compared with asymptomatic controls, the leading edge remained in the hypopharynx before swallowing longer in stroke subjects (P = 0.016) and was lower in the foodway at swallow onset with two-phase food (P = 0.03) and liquid (P = 0.06). Penetration-aspiration scores were significantly higher for liquid and two-phase ingesta when the leading edge was deeper in the pharynx at swallow onset (P = 0.03). These findings suggest that stroke alters the coordination of bolus transport and swallowing, particularly with foods containing a liquid phase. With such an impairment, a bolus may enter the hypopharynx prematurely, thus increasing the risk of aspiration.

Isolated Pharyngeal Swallow Exists during Normal Human Feeding

Swallowing is one of the basic activities in humans. The pharynx functions as an airway and a food channel, and a pharyngeal swallow usually occurs after bolus transport from the oral cavity. However, direct fluid infusion through a catheter into the hypopharynx produces a pharyngeal swallow without the oral stage in experimental situations. The purpose of this study was to examine whether a pharyngeal swallow, which is not accompanied by bolus transport, can occur during normal human feeding. Fifty-three healthy volunteers (25-89 years) were recorded, via videofluoroscopic examination of swallowing, during 3 different swallowing trials: command swallow of 10 ml liquid barium, chew-swallow of corned beef, and chew-swallow of a mixture of corned beef and liquid barium. Subsequently each swallow was classified as being either a consecutive pharyngeal swallow (CPS), following transport, or an isolated pharyngeal swallow (IPS), without immediately prior transport. The location of the bolus at swallow initiation was also noted. Of 307 trials, 681 swallows were identified, which included 43 IPS and 638 CPS. IPS only occurred as the first swallow of a trial, but the frequency of IPS did not differ between 28 younger (< 60 years) and 25 older (≥ 60 years) people. Of the three food types, IPS occurred more frequently with the mixed food than with liquid. These results suggest that IPS may represent an airway protective mechanism. In conclusion, IPS occurs in normal swallowing during a daily eating situation. Swallowing is more complex than a simple reflex.