咬筋活動と舌骨上筋活動に基づく摂食行動の鑑別

Differentiation of Feeding Behaviors Based on Masseter and Supra-Hyoid Muscle Activity.

• Fumiko Uehara
• Kazuhiro Hori
• Kazuhiro Murakami
• Jumpei Okawa
• Takahiro Ono

抄録

咀嚼・嚥下障害のある高齢者には、ゼリーやピューレなどの軟らかい食べ物が与えられることが多い。このような半固形の食品は、その食感から、噛むというよりも舌と口蓋の間に挟んで食べることができます。しかし、このような食品の口腔処理の戦略を視覚的に識別することは困難である。本研究では、咬筋と舌上筋の連続的な協調性に違いがあるという仮説を検証し、筋電図を用いて咀嚼や絞りなどの摂食行動を同定することを目的とした。被験者は男性17名（平均年齢30.8歳）を募集した。試験サンプルとして4種類のゲル（破壊力と破壊ひずみの2種類）を用意した。被験者には、舌で絞る、歯で噛む、飲み込むまで自由に食べるの3つの方法でゲルを摂取するように指示した。舌で絞る・噛むの量と消費時間は無制限であった。咬筋と舌上筋活動を全消費時間中に記録し、各摂取時には同時にビデオフルオログラフィーで記録した。最初のストローク中の両群の筋電図活動からリサージュ図形を作成し、Mann-Whitney-検定を用いて絞りと咀嚼を比較するための各図形の勾配を決定するための回帰線を作成した。舌での咀嚼時には咬筋と舌骨上筋が同時に活動していたが，咀嚼後には咬筋が活動していた。咀嚼時には、舌圧筋と舌骨上筋が同時に活動していたが、咀嚼時には舌圧筋が舌骨上筋の後に活動していた。咬筋と舌骨上筋の活動の間のLissajous図形からの回帰直線の勾配は、咬合時には正であったが、咀嚼時には負であった。ROC曲線を解析した結果，摂食行動を区別するための勾配のカットオフ値は0.097で，感度は95.3％，特異度は98.4％であった。このカットオフ値に従って68個の自由摂取量を絞りと咀嚼に分けたところ、精度よく区別でき、精度は86.8、感度は91.1、特異度は66.7%であった。これらの結果から、口腔処理法によって筋活動のある側面が異なっていることが示唆された。筋活動のリサージュ分析は摂食行動の識別に有用であった。

Older adults with disorders of mastication and swallowing are often fed soft foods such as jelly or puree. The texture of such semi-solid foods allows them to be squeezed between the tongue and palate rather than being chewed. However, it is difficult to visually identify such strategies for the oral processing of food. This study aimed to test the hypothesis that there is a difference in the sequential coordination between the masseter and supra-hyoid muscles, and to identify feeding behaviors such as chewing and squeezing using electromyography. Seventeen male subjects (mean age: 30.8 years) were recruited. Four kinds of gels were prepared (two kinds of fracture force and fracture strain) as test samples. Subjects were instructed to consume the gels in three ways: squeezing with the tongue, chewing with the teeth and eating freely until swallowing. The amount of squeezing/chewing and the consumption time was unlimited. The masseter and supra-hyoid muscle activity were recorded during the entire consumption time and videofluorography was simultaneously recorded during each ingestion. Lissajous figures were made from the electromyographic activity of the two groups of muscles during the first stroke, and a regression line was made to determine the gradient of each figure to compare squeezing and chewing using the Mann-Whitney -test. The masseter and supra-hyoid muscles were active simultaneously during squeezing with the tongue. However, the masseter was active after the supra-hyoid during chewing. The gradient of the regression line from the Lissajous figures between the masseter and supra-hyoid muscle activity was positive during squeezing, but negative during chewing. Analysis of the ROC curve showed that the cutoff value of the gradient for differentiating feeding behaviors was 0.097, with a sensitivity of 95.3% and specificity of 98.4%. When we allocated 68 free intakes into squeezing and chewing according to this cutoff value, we could distinguish with good precision, and the accuracy, sensitivity, and specificity were 86.8, 91.1, and 66.7% respectively. These results suggest that certain aspects of muscle activity differed among oral processing methods. Lissajous analysis of muscle activity was useful for identifying ingestion behaviors.

Copyright © 2020 Uehara, Hori, Murakami, Okawa and Ono.