An Anthropometric Assessment of Mandibular Growth In Pierre Robin Sequence

BACKGROUND

While data regarding short term efficacy of various treatment modalities in relieving tongue-based airway obstruction in the neonatal period is available, there is a paucity of data about the long term growth potential in the Pierre Robin population.  The purpose of this study is to evaluate long-term mandibular growth via anthropometry in children with PRS from a single tertiary referral center, comparing those treated with prone positioning alone to those treated with tongue-lip adhesion. 

METHODS

All patients with isolated PRS assessed by anthropometry at Children's Hospital of Philadelphia from 1983 to 2010 were included in the study.   Of the 135, 89 were treated with prone positioning alone and 46 with tongue-lip adhesion.  Standard anthropomorphic measurements were taken at each clinic visit beginning at age 2, and representative age-matched measurements of mandibular morphology were compared by method of treatment.  To gain perspective, age-matched historical control data (Farkas) were used.  Each treatment group mean was compared to Farkas's norms (mean and standard deviation only) using parametric t tests.  Treatment groups were compared to each other using a non parametric Mann-Whitney U test.

RESULTS

Mandibular length in isolated PRS was 92.4mm at age 2, grew an average of 3.2mm annually in the first 5 years, and remained consistently behind Farkas's norms.  There was no statistically significant difference in length between the TLA and positioning groups, and both groups trended towards slightly smaller lengths as compared to Farkas' controls.  The ratio of lower facial height to total facial height averaged 50% in PRS treated with either TLA or prone positioning alone and 60% in Farkas's controls.  These groups were statistically distinct across all age groups (p < 0.006).

DISCUSSION

These data represent the largest quantitative series of growth measurements in PRS patients.  They support the concept of mandibular “catch up” growth to some extent for both those treated with prone positioning alone and those treated with TLA.  While the PRS mandible does not reach the dimensions of Farkas's controls, and with respect to lower facial height remains statistically significantly shorter through skeletal maturity, these measurements provide a level of comfort with the use of temporizing measures in the neonatal period at least where mandibular length is concerned.