CRANIOFACIAL VARIABILITY INDEX - A SIMPLE MEASURE OF NORMAL AND ABNORMAL VARIATION IN THE HEAD AND FACE

We propose a numerical means of increasing the objectivity of describi ng, characterizing, and evaluating craniofacial morphology, including dysmorphology, A craniofacial variability index (CVI) can be created f or an individual by obtaining a series of anthropometric measurements of the head and face, converting each measurement value to a standardi zed z-score, and then calculating the standard deviation for the whole set of these z-score values. This value is lowest for those faces in which all of the z-scores are in the same direction and of relatively the same magnitude and highest for faces with pronounced difference in direction and size of the individual z-scores, The CVI has a range of values with an approximately normal distribution in a reference popul ation of 1,312 individuals. Examination of a small sample of individua ls with known craniofacial syndromes indicates that the CVI in such ca ses consistently falls outside of the normal range of the index, and i ts value is highest in individuals with the greatest subjective degree of facial involvement. Finally, the CVI is robust: age, sex, size of the individual, and changes in the number of variables used in its cal culation have little impact on its distribution. When used in conjunct ion with traditional clinical assessment, the CVI has a number of pote ntial clinical applications including initial diagnostic screening, de monstrating age-related changes in postnatal development of patients w ith facial syndromes, and pre- and post-surgical assessments of indivi duals with craniofacial anomalies. (C) 1998 Wiley-Liss, Inc.