Craniofacial morphology and growth in young patients with congenital or childhood onset myotonic dystrophy

Abstract

This study investigated the craniofacial morphology of young individuals with congenital or childhood onset myotonic dystrophy type 1 (DM1) compared to healthy subjects. The study also followed growth changes in their facial morphology over a 5-year period. Lateral cephalograms of the 26 subjects (young patients with DM1 from west and south Sweden) were taken at baseline and after a 5-year period. These radiographs were compared with normal standards based on healthy individuals from the Michigan Growth Study, according to their age and sex, using paired t-tests (P < 0.05). On examination of initial radiographic measurements, patients with DM1 showed, in the sagittal plane, larger ANB and smaller SNPg angles. Analysis of the vertical plane showed the mandibular plane angle (ML-NSL) and the intermaxillary angle (ML-NL) to be larger. During the 5-year follow-up period, the intermaxillary angle (ML-NL) remained the same in the group with DM1 whereas this angle decreased in healthy individuals. For ethical reasons, historical cephalometric norms were used to compare the growth and the craniofacial morphology of patients with DM1. Young patients with DM1 had already from the beginning a more retrognathic profile and hyperdivergent skeletal aberration with a steep mandibular plane and large intermaxillary angle when compared with healthy individuals. The intermaxillary angle did not decrease during the observation period, contrary to what was observed in healthy individuals.