Development of a Simple Evaluation Method for Tongue Motor Function Using a Hanging Scale

Abstract

　In this study we developed a novel quantitative evaluation method for tongue motor function using a hanging scale, which has the advantages of easy introduction and low cost. The maximum value at which gauze can be held by the tongue and palate, measured with a hanging scale, is called the “maximum holding force” and is used as a new evaluation index. Thirty-seven inpatients aged 65 years or older (21 males and 16 females, mean age 77.1±5.9 years) participated in the trial of our method. The relationships between the maximum holding force and existing indexes, such as maximum tongue pressure, tongue pressure during effortful swallowing, number of left and right tongue movements, and oral diadochokinesis of /ta/ and /ka/, were investigated. Regression analysis was performed to evaluate the accuracy of the regression equation, to obtain the maximum tongue pressure from the maximum holding force. The maximum holding force was significantly correlated with maximum tongue pressure, tongue pressure during effortful swallowing, number of left and right tongue movements (p＜0.001), and repetition of the monosyllable /ta/ (p＝0.016). The regression equation was obtained as maximum tongue pressure (kPa)＝ 6.678＋7.457×maximum holding force (kgf) (p＜0.001) with 0.713 coefficient of determination. The intra-rater reliability of the maximum holding force was 0.95 (p＜0.001), and the inter-rater reliability was 0.93 (p＝0.003) on average. We concluded that the maximum holding force is a useful index reflecting the motor function of the tongue and that our method can provide a quantitative assessment in clinical practice at low cost.