Do post-surgical unilateral cleft lip and palate patients have a comparable dynamic facial expression to a non-cleft population?

Patel, Yatisha Ashok (2021). Do post-surgical unilateral cleft lip and palate patients have a comparable dynamic facial expression to a non-cleft population? University of Birmingham. M.Res.

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Abstract

Aim: The aim of this study was to determine if the dynamic movement of the naso-labial region was similar between cleft adult patients, at the end of their treatment journey, and an age and gender matched control group.

Design: Single centre, case-controlled study

Materials and methods: Thirteen participants, who met the specific inclusion criteria, were invited voluntarily to be imaged performing a maximum smile using a 3D facial motion capture system. The control group was selected consisting from a larger pool of 54 male and 54 female non-cleft volunteers, previously imaged using the same system. Images were re-orientated according to the principle planes, and 17 landmarks were digitally placed and automatically tracked, 4 were used for stabilisation and the remainder for analysis. The x, y and z co-ordinates of the tracked landmarks were used to analyse the magnitude of displacement of bilateral structures either side of the midline and to calculate the path of motion of the bilateral structures. Mesh tracking was used to produce an asymmetry score to assess the shape of the mouth and / nose when mirrored onto itself around the clinical midline, and when trying to achieve the best fit using Procrustes analysis at rest, mid-smile and a maximum smile.

Results: Maximum displacement of right and left corners of the mouth, in the x, y, z direction and Euclidian distance were statistically significantly (p<0.05) less in the cleft group (20-40% less) compared to the control group during maximum smile. This was greater than 3mm, therefore clinically significant. There was a baseline level of asymmetry in the control group (range 0.7-0.9mm), as right and left corners of the mouth did not follow the same path of motion. This difference was larger in the cleft group (range 1.0-2.0mm). At each time point, the asymmetry score of the lips when smiling and reflecting around the clinical midline was statistically significantly more (p<0.05) in the cleft group compared to the control group. When assessing the symmetry of the lips using Procrustes superimposition, the difference between the two groups was statistically significant (p<0.05) at rest and median smile, however not statistically significant at maximum smile.
The alar bases were displaced statistically significantly less (p<0.05) in the z direction in the cleft group (1.2mm) compared to the control group (2.1mm), and was clinically significant when assessing the alar base of the affected cleft side. The path of motion of the alar bases was similar in both groups. During smiling, the asymmetry score of the alar base, was statistically significantly higher when reflected around the clinical midline then when using Procrustes superimposition for cleft patients (p<0.001) at each time point, compared to the control group. At maximum smile, there was less displacement of right and left cristae philtre, in the x, y, z direction and Euclidian distance, for the cleft group compared to the control group. The affected cleft side moved statistically significantly less (p<0.05) in the x and z-direction. There was a baseline level of asymmetry of path of motion of the right and left crista philtre demonstrated in the control group, with a greater degree of difference present in the cleft group.

Conclusions: There was statistically (p<0.05) and clinically significantly (>3mm) less displacement (Euclidian distance) of the corners of the mouth in cleft patients compared to the control group. The corners of the mouth did not follow the same path of displacement. There was an increase in asymmetry score of the corners of the mouth and alar bases from rest to maximum smile. As the asymmetry scores were larger using the clinical midline rather than the Procrustes method, this would suggest that the lips were similar in shape but orientated differently in the face of cleft patients compared to non-cleft individuals.

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

Supervisor(s):