Morphological integration of the skull in craniofacial anomalies

Abstract

OBJECTIVES - To understand how surgical interventions impact the organization and internal integration of the major components of the skull, we address the functional and developmental relationships during perinatal development. METHODS - A number of methods for quantifying modularity and integration of morphological data are available. Here, measures derived from three-dimensional computed tomographic (CT) images are used to investigate the statistical relationships among measures of the cranial vault, face and cranial base. First, we establish the pattern of associations among quantitative measures in a sample of children unaffected by a craniofacial anomaly. We statistically compare these normative patterns of cranial integration to those of a sample of children with a facial anomaly (complete unilateral complete cleft lip and palate), and to children with a neurocranial anomaly (isolated sagittal synostosis). Finally, we test whether surgery affects the strength and pattern of associations among measures within the cranial base in the affected children. RESULTS - Our analyses reveal strong internal integration of the cranial base in unaffected children and in our samples of unoperated cleft lip and palate, and sagittal synostosis. Post-operatively, the magnitude of integration of the cranial base is reduced relative to the pre-operative condition in both samples of children with craniofacial anomalies. CONCLUSION - Our results show how the cranial base adjusts to its broader structural context, and provides added support for the developmental and structural integration of cranial base with both cranial vault and face.

Fig. 1

Twelve right-sided and midline landmarks located on 3D CT reconstructions (lateral view at left; ectocranial base at right) used in analysis. Landmark names are given in Table 2. *Sella (sel) is located endocranially, but its approximate location is shown on the ectocranial view.

Fig. 2

Graphic representation of our research design demonstrating the five comparisons between samples (boxes) used to test null hypotheses. See text for research questions and statement of null hypotheses.

Fig. 3

(A) Correlations within the face show the greatest number of significant differences in morphological integration between younger and older unaffected samples. There is no significant change within the cranial vault or within the cranial base. (B) Integration between measures from different modules shows a moderate number of significant differences.

Fig. 4

Linear distance pairs within the cranial base show significantly reduced integration in the post-operative ISS sample (left). Relative to the pre-operative ISS sample, the postoperative sample shows a marked reduction in the magnitude of morphological integration for linear distance pairs that include a measure from that portion of the cranial base anterior to foramen magnum (shown in pink) and a measure from the inferior portion of the posterior cranial fossa (shown in blue).