Assessment of soft tissue facial asymmetry in medically normal and syndrome-affected individuals by analysis of landmarks and measurements

We investigated soft tissue facial asymmetry in normal and syndrome-affecte d individuals ranging in age from 1 year to adulthood. The purposes of our study were to determine if facial asymmetry was greater in syndrome-affecte d individuals than in normal individuals and, if true, to distinguish those measurements that could be used in routine screening to identify the prese nce of syndromes in uncertain patients and, lastly, to investigate the caus es of measurement asymmetry at the level of the landmarks, The last purpose was possible because we used a stereophotogrammetric method with which the three-dimensional (3D) landmark positions were obtained. In the statistica lly significantly different measurements, those from the right side were do minant, with one exception in each group, except normal males. In all group s the landmark analyses demonstrated the same trends, and while there was f ar less patterning in the 3D coordinates, these results were also consisten t between the four groups. We compared the statistical findings of the 3D c oordinates and measurements and found that there was no predictable relatio nship between significant findings in the landmarks and the measurements. I n particular, we noted that statistical differences in measurements did not infer significant differences in the positions of the landmarks between th e right and left sides of the face. Both the normal and syndrome-affected g roups appeared to be equally canalized and similarly affected by developmen tal noise: When the bilateral measurement differences of each syndrome-affe cted subject were compared to the limits of normal asymmetry, less than 10% of the comparisons exceeded the norms, (C) 2000 Wiley-Liss, Inc.