Quantitative evaluation of facial palsy by contour extraction of facial features

At present, in the medical field 40 points method and facial nerve grading system are generally used for evaluation of facial palsy. However, these methods have limitation in the precise evaluation, because subjectivity of each doctor in charge influenced the clinic results, and there are some problems in terms of reproducibility in diagnosis. It is also difficult to understand how patients are recovering from these evaluation methods. Some approaches have been tried to solve these problems. But they are not widely applied to real diagnosis. Purpose of this paper is to extract contours of facial features and to propose quantitative evaluation of facial palsy. Facial nerve symptons generally appear in either side of the face. Therefore we used contour of eyes, a lip and wrinkle as features, noting that the symmetry of facial features. Contours of facial features of many subjects were extracted, after subject's faces were taken to digital videotapes. We used four facial expressive motions for diagnosis of some healthy persons and palsy subjects. We defined some indices of evaluation of palsy grade. These indices showed shape of facial features quantitatively. We confirmed from results of observation that the recovery process was quantitatively shown.