Quantitative evaluation of facial movement and morphology

The aim of our study was to quantitatively analyze facial motion kinematics by means of an optoelectronic system. In particular, we defined a set of easily recognizable reference points for markerization, and tested the applicability of our markerization method for an exhaustive characterization of the subjects' facial motion through the definition of some kinematic parameters.

Thirty healthy subjects (mean age, 24.6 +/- 1.0 years; 15 female and 15 male) participated in the study. A set of markers (diameter, 3 mm) was positioned on several reference points of the face, and some parameters were computed for the characterization of facial morphology and movement, such as ranges of motion, angles, times, and distances.

The protocol was tested for inter-rater and intra-rater reliability by use of intraclass correlation, of which the results were good (between 0.4 and 0.75) to excellent (greater than 0.75). The parameters were useful for characterizing the resting position, mimicry, and speaking movements, and highlighted some distinctions between men and women in facial morphology.

The protocol can be applied to a variety of facial movements, including speaking. Future works could address the use of the protocol in subjects with disorders and the integrated analysis of kinematic parameters and voice spectrography.