Three-dimensional video analysis of facial movements: A new method to assess the quantity and quality of the smile

The results of neuromuscular reconstructions of the paralyzed face are diff icult to assess. Very sophisticated methods are necessary to measure the mo tor deficits of facial paralysis or the functional recovery in the face. Th e aim of this development was a relatively simple system for data acquisiti on, which is easy to handle and which makes it relatively cheap to delegate data acquisition to centers all over the world, which will not be able to derive a data analysis on their own, but will send their data to a center w ith specialized equipment. A complex mirror system was developed to get thr ee different views of the face at the same time on the video screen. At eac h investigation, a digital video is taken from a calibration grid and from standardized facial movements of the patient. Secondary analysis of the dig ital videofilm is made possible at any time later on by the support of a co mputer program, which calculates distances and movements three-dimensionall y from the frontal image and the right and left mirror images. Pathologies of the mimic movements can be identified as well as improvements after surg ical procedures by this system. The significant advantage is the possibilit y to watch the same movement on the video which is under study and to apply any kind of study later on. Taking the video needs only a few minutes, and fatigue of the patient's mimic system is prevented. Measurements usually a t the endpoints of the movements give excellent information on the quantity of the movement or the degree of the facial palsy, whereas the video itsel f is very informative regarding the quality of the smile. Specific computer software was developed for standardized three-dimensional analysis of the video-documented facial movements and for data presentation. There are opti ons like two-dimensional graphs of single moving points in the fare or thre e-dimensional graphs of the movements of all measured points at the same ti me during a standardized facial movement. By a comparison of the right- and left-sided alterations of specific distances between two points during the facial movements, the degree of normal symmetry or pathologic asymmetry is quantified. This system is more suitable for detailed scientific multicent er studies than any other system previously established. A veri sensitive i nstrument fur exact evaluation of mimic function is now available.