Facial Malformation in Crouzon's Syndrome Is Consistent with Cranial Base Development in Time and Space.

Background: In Crouzon's syndrome, cranial base deformities begin sequentially in the anterior cranial fossa initially, and later to the posterior cranial base. Facial characteristics are likely related to cranial base development. The temporal correlation between cranial base development and facial features is in need of clarification in Crouzon's patients, to clarify initial sites of deformity, which may impact surgical decision making.

Methods: Thirty-six computed tomography scans of unoperated Crouzon's syndrome patients and 54 controls were included and divided into 5 age-subgroups. All the planes used for analysis were set as perpendicular to a defined "midplane" to offset the confounding factor caused by potential asymmetry.

Results: The angle between Sella-Nasion plane and Frankfort horizontal plane was significantly increased before 6 months of age ( = 0.014), with an average 70% ( < 0.001) increase ultimately into adulthood. The angle between SN and maxillary plane and the angle between Sella-Nasion and occlusal planes increased consistently through infancy to adulthood (124% and 42%, respectively, both < 0.001). The relative angle of mandibular plane to Frankfort horizontal plane increased before 6 months (28%, = 0.007) with a peak timeframe from 2 to 18 years. Facial lateral curvature related measurements indicate the whole face is inclined posteriorly and inferiorly direction in relation to the anterior cranial base.

Conclusion: Crouzon's facial malformation development is synchronous and positionally correlational with cranial base deformity. It transmitted from orbit to mandible, with the most evident morphologic changes are in the orbit and midface.