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

Background/objectives: 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.

Materials/methods: 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).

Results: 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.

Limitations: For ethical reasons, historical cephalometric norms were used to compare the growth and the craniofacial morphology of patients with DM1.

Conclusions/implications: 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.