Disruption of symmetry: A quantitative assessment of facial skeleton anatomy in children born with unilateral cleft lip and palate

: Unilateral cleft lip and palate (UCLP) is a craniofacial deformity characterized by lip and palate clefting on one side of the face. UCLP originates from failures in neural crest migration and differentiation during embryological development, impairing facial primordia fusion (medial nasal, maxillary, and lateral processes) resulting in clefting. Persons with UCLP experience issues in nasal breathing, speaking, and mastication. Facial directional asymmetry (DA), consisting of left-right side differences biased toward one particular side, can arise from environmental or hereditary factors. This retrospective, cross-sectional study, quantifies DA in the facial skeleton of children with surgically repaired UCLP. We tested the hypothesis that DA is significantly increased in persons with UCLP. Twenty-three anatomical landmark coordinates were measured from cone beam computed tomography images of two age- and sex-matched samples: (1) persons with UCLP post-surgery (n = 26, 7-17 years); (2) typical children (n = 26, 7-17 years). From these coordinates, 81 bilateral paired measurements were calculated and statistically assessed for DA differences using Principal Components Analysis and Euclidean Distance Matrix Analysis. Samples separate in high-dimensional space and 35.8% of bilateral measures are statistically significant. Patterns of significant DA differences between samples were explored based on magnitude. Compared with the control group, in all but five cases, significant DA was greater in persons with UCLP. Regions derived from the maxillary and nasal prominences demonstrated the most DA. These results are important for medical practitioners for identifying the extent to which patients with UCLP deviate from the norm. Clin. Anat. 31:1129-1136, 2018. © 2018 Wiley Periodicals, Inc.