高齢者における食塊の量・温度・味が嚥下反射惹起時の嚥下動態に与える影響

The effect of bolus characteristics on the dynamics of swallowing reflex initiation in elderly people

　高齢者を対象に，食塊の特性(量，温度，味)が嚥下反射惹起に与える影響を電気生理学的手法と嚥下困難感の主観評価を用いて検討した．

　電気生理学的検討として，試料を指示嚥下する際の舌骨上筋群筋活動と喉頭運動について筋電計と圧力センサを用いて計測した．嚥下困難感の主観評価は，5段階評定尺度法を用いて検討した．

　結果は，極端に少ない食塊量と水に比し味覚溶液で，嚥下合図から喉頭運動開始までの時間と嚥下反射に伴う舌骨上筋群筋活動の開始から喉頭運動開始までの時間が有意に延長した．口腔内に試料を滴下する本研究では，食塊の温度は嚥下動態に影響を与えなかった．嚥下困難感の主観評価では，味の違いのみに有意差を認めた．

　本研究より指示嚥下では，食塊の量や味の有無が，嚥下反射惹起に影響を与えることが示唆された．さらに，高齢者は嚥下運動と嚥下困難感が一致しないため，臨床においては両側面を評価し統合することが重要である．

　This study examined the effect of bolus characteristics(volume, temperature, and taste) on the movements involved with initiation of the swallowing reflex. Subjects studied were healthy elderly people. Movements involved with initiation of the swallowing reflex as measured using surface electromyography and a laryngeal sensor. Additionally, subjective difficulty of swallowing(SDS) was used as a psychological scale to evaluate subject's impression of swallowing. Results showed that bolus volume and taste influenced the duration of time between the instruction to swallow and the suprahyoid muscle activity, as well as the time between initiation of the suprahyoid muscle activity and onset of laryngeal elevation. Moreover, we found that bolus temperature did not influence the movements involved with initiation of the swallowing reflex in this study. With respect to subjective evaluation, we found that bolus taste significantly influenced SDS. Our study suggests that the volume and taste of the bolus affect initiation of the swallowing reflex via a voluntary swallowing mechanism. Furthermore, in elderly people, the psychological aspect in relation to SDS does influence initiation of movements involved with swallowing. Therefore, it is important to evaluate both the psychological aspect and physiological movements associated with swallowing during swallowing assessment in elderly people.