The Correlation Between The Movement Of Facial Markers Around The Rima Oris And The Rima Oculi In Facial Expressions:a Preliminary Quantitative3-Dimensional Analysis

ObjectiveThis study aimed at establishing a quantitative3D method to evaluate synkinesis, which is a common and distressing sequela of facial paralysis. We set several facial markers around the rima oris and rima oculi to detect the contractions of the muscles there. This study is a preliminary one which aimed at validating the reliability, accuracy and feasibility of this3-dimensional dynamic quantitative analysis system in the evaluation of the correlations between the movements of these facial markers, and then using this system to collect data of the healthy volunteers.Methods(1) Using "the3-D facial motion capture and analyze system", which is designed by the ENT department of Peking Union Medical College Hospital, as a tool;(2)35healthy volunteers who can be divided into two groups based on age took part in this research;(3) We choose the marker points located near the voluntary moving region as reference markers, and those located far away from this region as observation markers. Based on the previous studies, we chose the maximum moving distance and maximum velocity of the facial markers as indicators of facial movement.(4) Collecting the raw data of all the volunteers, and using the3DMoCap software to trace the moving patterns of all the facial markers. This software can give us the information of these movements in forms of the3D coordinate of the markers. We can work on these coordinates with the help of a computer to get all the information we want. In this research, we calculated the maximum moving distance and maximum velocity.(5) Medical statistical analysis.Results(1) The intraclass correlation coefficients (ICC) of this3-dimensional dynamic quantitative analysis system in the evaluation of the correlated movement between our facial markers are quite well.(2) The evaluation of time consistency got the results that the time point of each observation marker to obtain its maximum distance and maximum velocity is same as the time point of the reference marker (P>0.05).(3) The reference marker’s maximal values of the maximum distance and the maximum velocity take place in the widely mouth open expression, whose reference marker is the middle of the lower lip. The observation marker’s maximal values take place in the markers of palpebra superior in voluntary oral movements. And the minimal values take place in the angulus oculi medialis and geisoma markers’ movement in smiling.(4) We use the observation marker’s moving distance while the reference marker obtain its maximum distance divided by the observation marker’s maximum distance to get a proportion of distance; and the similar calculation is used to get the proportion of the observation marker’s velocity. We use these two proportions to evaluate the completeness of the observation markers’ movements. The mean value of the proportion of distance is higher than the proportion of velocity. The markers of nasolabial groove and corner of mouth in raising eyebrow, and the markers of amgulus oculi lateralis and palpebra inferior in widely opening mouth and showing teeth get higher proportions than other markers.(5) Raising eyebrow (reference marker-left/right geisoma), showing teeth (reference marker-right corner of mouth), widely opening mouth (reference marker-middle upper lip), and lifting the right corner of the mouth to the right and upper direction, in these four expressions, there are higher linear relationships between the observation markers’ moving distance and velocity and that of the reference marker (P<0.05).(6) As for the differences between the two group, the maximum moving distance of the markers located around the voluntary muscles gain significant difference (P<0.05) and G1>G2; The maximum moving distance of the observation markers include the left/right palpebra superior and left/right geisoma in widely opening mouth, and left geisoma in lifting the right corner of the mouth to the upper-right direction, lifting the left corner of the mouth to the upper-left direction and smiling, gain the significant difference (P<0.05) between the two groups and G2>G1. The maximum velocity is G2>G1, except for the left angulus oculi medialis in forced closing eyes is G1>G2.Conclusions(1) Using maximum moving distance and maximum velocity as indicators, set reference markers and observation markers for different expressions, with the help of "the3-D facial motion capture and analyze system", we can analyze the correlation between the movement of facial markers around the rima oris and the rima oculi in facial expressions. It will be a hopeful and useful tool to evaluate synkinesis in a3D quantitative way, with good reliability, accuracy and feasibility.(2) Collected3D quantitative data of healthy volunteers about the correlation between the movements of facial markers in different regions of face in some expressions, gain the reference value in healthy persons, and analyzed the linear correlations between the observation markers and the reference marker.(3) Compared the differences of the correlation of the movement of the facial markers in different regions in younger group and older group in a quantitative way to evaluate the age-related changes in facial expressions and facial movement.