Association of Regional Cranial Base Deformity and Ultimate Structure in Crouzon Syndrome.

BACKGROUND: Considerable craniofacial features of Crouzon syndrome are attributed to the dysmorphology of the cranial base. As cephalometric studies have focused mainly on the facial deformity, rather than the cranial base, the underlying cause of deformity is not as well understood. Therefore, the authors compared the cranial base development of Crouzon syndrome to controls to trace the timing of deformity in the cranial base and face, to analyze their temporal correlation.

METHODS: Ninety computed tomographic scans were included (Crouzon, n = 36; controls, n = 54) and divided into five age subgroups. Craniofacial cephalometric measurements were analyzed by Materialise software.

RESULTS: The overall cranial base length in Crouzon syndrome compared with controls decreased 8 percent (p = 0.014) on average. The posterior cranial fossa shortening accounted for most of this reduction. The cranial base displaced with the distances from basion, sella, and ethmosphenoid to posterior nasal spine shortened by 21%, 18%, and 16%, respectively (all p < 0.01) during life. Although the cranial base angle on intracranial surface remains normal, the angles on facial surface narrowed were reduced.

CONCLUSIONS: The cranial base deformity of Crouzon syndrome consists of the whole skull base and particularly anterior skull base shortening early, leading to a compensatory widened anterior skull base. However, when this widening did not compensate fully for the rapid enlargement of the brain, the posterior skull base displaced inferiorly and became kyphotic. The cranial base deformity develops sequentially anterior to posterior in a probable cascade of influence pattern.

CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.