Surface anatomy of the face in Down's syndrome: age-related changes of anthropometric proportion indices in the craniofacial regions.

The purpose of the study was to determine the age-related changes in normal and abnormal proportion indices in Down's syndrome patients between 1 to 5, 6 to 15, and 16 to 36 years of age. Nine indices were analyzed in five craniofacial regions of 125 subjects: 70.2% to 79.0% were normal and 21.0% to 29.8% abnormal. Proportionate indices increased in frequency in all age groups in a much higher percentage than disproportionate ones. In the oldest group, the frequency of normal proportions significantly increased in the head and trended higher in the facial, orbital, and nasal regions, and lower in the ear. Disproportions showed a similar pattern, with a decreasing frequency in all regions except the ear. The variations of harmony and disharmony in normal proportions, and moderate and severe in disproportions, helped clarify the morphological changes influencing the craniofacial design. Among proportionate ratios, harmony ranged from 45% to 65.5% in age group 1 and from 30% to 87.5% in group 3. No cases of severe subnormal disproportions were seen in the nasal tip protrusion-nose width and nasal root depth indices in age group 1, and none in the cephalic index, midface-lower face depth, and nasal tip protrusion-nose width indices in group 3. The 20-year age range of group 3 helped show the post-maturation improvements of the face and the remedying effect of the extended growth rate on some initial facial disproportions.