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

The objective of the study was to identify the proportions closest to normal and those indicating mild-to-moderate and severe degrees of disproportion. Eight proportion indices were analyzed in five craniofacial regions of 125 Down's syndrome patients, based on a total of 985 data points. More than two thirds of the patients fell within the normal range, although more than one quarter were abnormal (disproportionate). All statistical summaries were based on z-scores (adjusting for age and sex differences), converted into descriptive anthropometric categories to yield a simplified frequency distribution for each proportion index. Normal proportions were harmonious in 55.9% of patients. Disproportions were mild to moderate in 66.4%, severe in 33.6%. The highest frequency of harmony was found in the head (70.2%), the lowest in the orbits (40.8%). The highest percentage of mild-moderate disproportion was found in the face (79.3%). The highest percentage of severe disproportions was recorded in the intercanthal index of the orbits (44.7%) and the smallest frequency in the face (20.7%). In the five craniofacial regions among the normal proportions, harmonies were more frequent than disharmonies. Among the disproportions, the percentage of mild-moderate ones was greater than those of severe degree.