Evaluating facial paralysis: A comparative study of 2D Emotrics and 3D scanning technologies

Facial asymmetry is a key indicator in evaluating facial paralysis, with both 2D and 3D imaging technologies offering distinct approaches to assessment. This study investigates the effectiveness of 2D Emotrics software and 3D scanning methods in quantifying facial asymmetry in patients with unilateral facial paralysis.

A cohort of 13 patients was assessed, and their facial movements-including brow raise, eye closure, and smile-were analyzed using both methods. Emotrics employed machine learning to automatically identify 74 facial landmarks on 2D photographs, facilitating rapid quantification of key metrics, while 3D scans provided a high-resolution, surface-based evaluation of facial movements through vertex comparisons.

Results showed significant correlations between Emotrics measurements and 3D analysis for most facial regions, with discrepancies primarily observed in complex areas like the mouth. While Emotrics demonstrated practical advantages in efficiency, the 3D scanning method captured finer surface changes, underscoring its clinical value for detailed assessments.

Our findings support a two-tiered clinical approach for facial palsy assessment. While 2D automated analysis is a reliable tool for rapid screening of the upper face, 3D scanning is essential for accurately evaluating complex smile dynamics, particularly for pre-surgical planning.