Facial motion analysis with a video and computer system after treatment of acoustic neuroma.

Abstract

To objectively evaluate facial function with a computer and video system in a group of normal adults and a group of adults who have been treated for acoustic neuroma. A prospective descriptive study was performed in which the experimenter performing the objective facial motion analysis was blinded to the subjective rating of facial function. The normal subjects comprised 18 women and 16 men. The subjects who had been treated for acoustic neuroma included 12 patients (seven women and five men) who underwent treatment for acoustic neuroma. Light-reflective markers were placed at selected facial sites. A video and computer-assisted system was used to measure displacement that was unconfounded by head motion at these sites during two expressions. Proximal and remote displacement were measured for the x and y coordinates. Percentage of asymmetry relative to the total displacement was determined. Significant asymmetry in displacement for the y coordinate during the eyes-closed expression occurred in 100% of the subjects who had been treated for acoustic neuroma with apparent facial dysfunction and 0% of the subjects who had been treated for acoustic neuroma with no apparent facial dysfunction. Synkinesis was severe (>0.2 cm) in 17%, moderate (0.1-0.2 cm) in 25%, mild (>95th percentile for normal subjects but <0.1 cm) in 42%, and absent in 16% of the subjects who had been treated for acoustic neuroma. This method of objective assessment of facial function is useful in the evaluation of the asymmetry in facial motion and in the detection and quantification of synkinesis. The findings suggest that those subjective rating systems of facial function that compare the abnormal to the normal side may be confounded by compensatory motion on the presumed normal side.