Surface anatomy of the face in Down's syndrome: Linear and angular measurements in the craniofacial regions

Measurements (23 projective linear, 2 angular) taken in the 6 craniofacial regions of 127 patients with Down's syndrome showed that 63.1% (1,836 of 2, 908) were within normal limits and 36.9% (1,072) were outside them. Abnorma l measurements were subnormal in 90.8% (973) and supernormal in 9.2% (99). All statistical summaries were based on z scores (adjusting for age and sex differences) classified into a small number of ranges to yield a simplifie d frequency distribution for each measurement. The purpose of the study was to identify the measurements closest to normal and those indicating the mo st severe degrees of sub- or supernormality. Approximately a quarter of nor mal measurements were classified as optimal, and half the subnormal or supe rnormal measurements were classified as severe. Intercanthal width had the highest frequency of optimal measurements (93.7%, 119 of 127), head circumf erence the smallest (28.6%, 36 of 126). Knowledge of the frequency of extre me abnormalities in the craniofacial regions will help during visual examin ation of patients with Down's syndrome. This study found the highest percen tage of severely subnormal measurements in the orbital region (57.8%, 74 of 128) and the smallest in the labio-oral region (32.7%, 16 of 49). The meas urement with the highest proportion of severely subnormal to all subnormal values was the palpebral fissure length (68%, 51 of 75), and the nose width had the smallest proportion (14.3%, 1 of 7).