Makoto Kawamoto

Quantitative analysis of synkinesis following facial nerve palsy

Abstract At present there is no standard objective and quantitative evaluation system of synkinesis following facial nerve palsy. We developed a computer-assisted evaluation system combined with a rating score and investigated the usefulness of video cameras and infrared cameras in this system for evaluating facial mimetic motion. Twenty-four markers were placed on the face and after the extracted images were labeled to leave only marks, using threshold-identified images, the trajectory length of a marker was calculated using the shift in points. Using a camera with a built-in infrared light flasher and higher sampling rates together with reflective markers, the velocity of each point could be evaluated. The trajectory length of the supralabial marker during eye closure and that of an infraorbital palpebrae marker during whistling were significantly longer in patients with postparalytic synkinesis than in normal subjects. The severity of synkinesis was rated using a 3-point scale ranging from 0 to 2 and we found that the velocity of the supralabial marker increased with the score. The results from the computer-assisted evaluation system and grading correlated closely and were useful for the clinical evaluation of synkinesis.

Objective Evaluation of Abnormal Associated Movements by Using an Infrared Camera: Eyelid Narrowing During Whistling

Results For the control group, the distance of marker movements of right side was correlated with left side. In the palsy group with the improvement of facial palsy, the right-and-left difference in the distance decreased and disappeared, as did the difference in the maximum velocity. On the other hand, even in palsy group whose facial expression had improved to normal, there was a right-andleft difference in the maximum velocity in the early stage.

Three-Dimensional Analysis of Facial Expression

Background The Sunnybrook Facial Grading System (FGS) was developed by Ross et al. in 1992 to evaluate facial function after facial nerve injury. This tool is clinically relevant, easy to administer, and requires no specialized equipment. It has clearly demonstrated ability to accurately describe patients’ facial function and monitor their recovery over time. It has strong measurement properties of content and construct validity, interand intra-rater reliability, and responsiveness to change.