State-of-the-art analysis of facial expression dynamics in unilateral cleft lip and palate cases using 4D imaging.

Abstract

To investigate the dynamics of lip movement, including the duration, magnitude and speed, in surgically managed patients with unilateral cleft lip and palate (UCLP) using sophisticated three-dimensional real-time video imaging of the face (4D). A retrospective comparative study of 31 surgically managed UCLP cases and 34 age and gender matched non-cleft cases. The maximum smile dynamics, including speed, magnitude and duration, were assessed using 4D stereophotographic images captured using a pair of video cameras at 60 frames/sec. A 3-second smile yielded 180 3D images for analysis. A set of digitised landmarks was used to assess the dynamics of maximum smile. The duration of the smile in cases with no cleft was much shorter than in the cases with UCLP (1.3 vs. 2 s). A measurable asymmetry was observed in the speed and magnitude of the philtrum between the two sides, with the cleft side being significantly slower (cleft 7.24 mm/s and non-cleft 8.22 mm/s). The speed of the lower lip landmarks was significantly greater on the cleft side (20.98 mm/s) than on the non-cleft side (19.22 mm/s). The speed and magnitude of movement for all upper lip landmarks in the cases with UCLP were significantly slower than in cases without cleft. Reduced speed and magnitude of lip movements in the cleft side of the upper lip indicates a restriction in muscular activity. This is likely to be due to lip scarring and incomplete repair of the muscles that contribute to distorted lip movement with maximum smile.