Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

Abstract

Objective

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Design

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Setting

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest’s Craniofacial Imaging Database (WFCID).

Patients

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

Interventions

None

Main Outcomes Measure(s)

2D and 3D cephalometric measurements.

Results

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = −398.75; P < .05) and petrous-occipital (β = −727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = −14 723.1; P < .001) and occipitomastoid synchondrosis (β = −16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = −673.3; P < .001), anterior intraoccipital synchondrosis (β = −368.47; P < .05), and posterior intraoccipital synchondrosis (β = −6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Conclusions

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.