Quantification of Facial Movements by Surface Laser Scanning

Abstract

Quantification of facial mimic ability represents a need for comparative investigation in facial medicine and surgery. The aim of the current study was to develop a simple, noninvasive, repeatable three-dimensional method for measuring facial mobility in clinical and research setup. The faces of 20 healthy adult subjects (10 men and 10 women) and 12 primary school children (6 boys and 6 girls), without craniofacial pathologic injuries or previous treatments, were captured by a Cyberware 3030RGB laser scanner (Cyberware, Inc, Monterey, CA) in rest position and during voluntary movements. Data were processed by Cyberware Echo (Cyberware, Inc) and Inus Rapidform 2004 software (INUS Technologies Inc, Seoul, South Korea). Each movement was assigned a main landmark. The facial movements were described for surface displacement using clearance vector mapping and three-dimensional tracing of the skin landmarks. The mean landmark displacement vector was also calculated for every movement. The study showed that movements were characterized by similar displacement in the same facial areas in all subjects. Minor differences were recorded between adult subjects and children. Descriptive statistics concerning the amount and direction of movements were provided. A case of unilateral postsurgical nerve palsy was prospectively analyzed to test applicability of the method in clinical investigation. A numerical scale based on the mean movements was constructed and used to monitor recovery of function.The method developed seems easy, noncontact, and effective to quantify facial movements in normal and pathologic conditions. It may be usefully applied to the investigation and the clinical monitoring of different medical and surgical pathologic conditions.