MRI and 3D Computer Modeling of the Levator Veli Palatini Muscle Before and After Primary Palatoplasty.

Abstract Objective: This study was designed for two purposes: (a) to obtain qualitative and quantitative information of the velopharyngeal mechanism in infants born with cleft palate before and after primary palatoplasty using MRI and 3D computer technology and (b) to demonstrate the potential of using computer technology and MRI for presurgical planning. Methods: Clinical MRI data were obtained from the medical charts of four infants (two with cleft lip and palate and two without) between 8 - 15 months of age. Computer technology was used to obtain quantitative measures of the levator veli palatini (levator) muscle and to create 3D computer models. Results: There was little difference in angles of origin between individuals with normal velopharyngeal anatomy (ranging from 41 masculine-45 masculine). Subjects with cleft palate displayed smaller angles of origins (average of 40 masculine) prior to surgery compared to that of the subjects without cleft palate (average of 43 masculine). Following surgery, the levator muscle increased in length (ranging from 32mm-40.4mm) and formed larger angles of origin (average of 39 masculine) becoming more similar to the angles of origin observed in the subjects without cleft palate. Conclusions: Although the subjects with normal anatomy displayed levator muscle lengths, thickness, and distance between origins that were dissimilar, nevertheless the angles of origin measures were similar. Subjects with cleft palate had greater variations in the angle of origin. It is possible that the angle of the muscle as it descends from the base of the skull might be a critical feature to produce velopharyngeal closure.