Assessment method of facial palsy by amount of feature point movements at facial expressions

At present in medical field, the 40 point method and facial nerve grading system (House-Brackmann method) are generally used for assessment of facial palsy. However, those methods have limitation in the precise assessment, because of subjectivity in diagnosis. Purpose of this paper is to propose objective and quantitative assessment of facial palsy based on the amount of feature point movements on the face. Facial nerve symptoms generally appear in either of right and left side on the face. In facial expression of palsy subjects, the motion on the diseased side becomes smaller than that on the healthy side. We defined some indices of palsy severity from the observation of facial expression. Those indices showed the asymmetry of the facial motion quantitatively. We confirmed that our proposed method was valid for assessment of the facial palsy by comparison with the 40 point method.