Evaluation of the Pierre Robin Sequence Mandible Using Computed Tomography

Infants born with Pierre Robin Sequence (PRS) have airway obstruction and consequently have respiratory difficulties. The severity of the respiratory difficulty varies among patients. Many such patients are candidates for mandibular distraction osteogenesis (MDO) to address the airway obstruction and improve their respiratory status. The decision to perform MDO is typically based on the severity of the airway obstruction and is entirely a clinical decision. Little information is known regarding the anatomic description of a typical Pierre Robin mandible.

The purpose of this investigation is to compare the mandibular morphology of a Pierre Robin Sequence infant to unaffected infants using computed tomography.

This is a retrospective cohort study composed of subjects who underwent routine computed tomographic (CT) evaluation of the maxillofacial region. One group is comprised of infants with a diagnosis of Pierre Robin Sequence and the other is of unaffected subjects. The sample is derived from a population of patients who had a CT performed at New York Presbyterian Hospital/Columbia University Medical Center from January 2012 to December 2015. Inclusion criteria call for all patients with PRS and unaffected control-matched patients who have underwent CT. There are no exclusion criteria. Researchers from the Departments of Oral and Maxillofacial Surgery and Pediatric Radiology evaluated each mandible. Anatomic and morphologic variables are indentified for each subject. The outcome variables measured for each patient were mandibular body length and mandibular ramus height. Unpaired t-tests were computed for each outcome variable. The level of statistical significance was P < .05.

The study sample included 10 subjects, 5 infants with Pierre Robin Sequence and 5 unaffected subjects. The median age for the Pierre Robin group was 2 months (range, 1-4 months; mean, 2.2 months). The median age for the control group was 8 months (range, 4-28 months; mean, 12.2 months). The mean mandibular body length was 35.6 mm in Pierre Robin group and 45.2 mm in the control group. The unpaired t-test demonstrated a statistically significant difference with a P value of 0.03. The mean mandibular ramus length was 21 mm in Pierre Robin group and 30 mm in the control group. The unpaired t-test demonstrated a statistically significant difference with P value is 0.02. This data demonstrates that the Pierre Robin Sequence mandible is reliably smaller in both mandibular length and ramus height.

The study results suggest that infants with Pierre Robin Sequence have significantly smaller mandibles when compared to unaffected infants. Results from this study help more accurately characterize the Pierre Robin Sequence mandible. This information may help clinicians set anatomical parameters to more precisely define diagnostic criteria for Pierre Robin Sequence. Additionally, it may more accurately predict which patients are best suited for MDO.

References:

1) Chung MT et al: Pierre Robin Sequence and Treacher Collins Hypoplastic Mandible comparison Using Three-Dimensional Morphometric Analysis. Journal of Craniofacial Surgery. Volume 23, Supplement 1, November 2012.

2) Figueroa AA. et al: Mandible, Tongue, and Airway in Pierre Robin Sequence: A Longitudinal Cephalometric Study. Cleft Palate-Craniofacial Journal, Volume 28, Number 4. October 1991.