Objectives: In patients with facial paralysis, facial reanimation surgery may be needed to normalize facial soft tissue function/movements. Critical for this normalization is the dynamics of the nasolabial folds (NLFs). The objective of this prospective, observational study was to determine the 3D morphologic dynamics of the NLFs in patients with unilateral facial palsy and normal subjects.
Settings and sample population: 3D facial soft tissue movement data collected from adults with unilateral, facial paralysis (Bell's Palsy, n = 36); and (2) an age- and sex-frequency matched control group (n = 68).
Materials and methods: Movement data were collected during repeated animations from participants using a video-based motion capture system. Movement in terms of displacement and asymmetry of the NLFs, nasal and circumoral regions were analyzed in the lateral, vertical and depth planes; as well as movement of the commissure and NLFs relative to the lower lip midline. Two-sample t tests were used to test for significant group differences.
Results: Patients NLFs had less mean displacement, greater mean asymmetry and uncoordinated movements compared with the controls. For both groups during smiling, the NLF and commissure landmarks had approximately similar magnitudes of displacement (control range = 11-14mm; patient range = 7-10mm).
Conclusion: NLF dynamics during smiling were as significant as oral commissure excursion. Thus, an immobile NLF is an unnatural feature of facial animations. Surgical treatments that address impaired NFL movements must be considered to create a more natural surgical outcome especially during smiling.
Keywords: Bell's palsy; facial paralysis; nasolabial fold; smile reanimation.
© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.