Skulls of Fgfr2(C342Y/+) mice differ from normal littermates in a comparable manner with differences between the skulls of humans with Crouzon syndrome and those of unaffected individuals. These findings were consistent across several regions of anatomic interest. Further investigation into the molecular mechanisms underlying the anomalies seen in the Crouzon mouse model is currently under way.
A variety of commercially available three-dimensional (3D) surface imaging systems are currently in use by craniofacial specialists. Little is known, however, about how measurement data generated from alternative 3D systems compare, specifically in terms of accuracy and precision. The purpose of this study was to compare anthropometric measurements obtained by way of two different digital 3D photogrammetry systems (Genex and 3dMD) as well as direct anthropometry and to evaluate intraobserver precision across these three methods. On a sample of 18 mannequin heads, 12 linear distances were measured twice by each method. A two-factor repeated measures analysis of variance was used to test simultaneously for mean differences in precision across methods. Additional descriptive statistics (e.g., technical error of measurement [TEM]) were used to quantify measurement error magnitude. Statistically significant (P < 0.05) mean differences were observed across methods for nine anthropometric variables; however, the magnitude of these differences was consistently at the submillimeter level. No significant differences were noted for precision. Moreover, the magnitude of imprecision was determined to be very small, with TEM scores well under 1 mm, and intraclass correlation coefficients ranging from 0.98 to 1. Results indicate that overall mean differences across these three methods were small enough to be of little practical importance. In terms of intraobserver precision, all methods fared equally well. This study is the first attempt to simultaneously compare 3D surface imaging systems directly with one another and with traditional anthropometry. Results suggest that craniofacial surface data obtained by way of alternative 3D photogrammetric systems can be combined or compared statistically.
Though reduction in the number of cranial elements through loss of a suture is a recognized trend in vertebrate evolution, the premature closure of cranial sutures in humans, craniosynostosis, is considered a pathological condition. Previous research on craniosynostosis has focused primarily on the skeletal phenotype, but the intimate relationship between the developing central nervous system (CNS) and skull is well documented. We investigate the morphology of the CNS in patients with isolated craniosynostosis through an analysis of cortical and subcortical features using 3-D magnetic resonance images (MRI). Results show that a distinct CNS phenotype can be defined for specific diagnostic categories. Many differences in CNS morphology observed in the patient samples may be anticipated based on skeletal morphology, but others are not reflected in the skull. We propose a developmental approach to determining the cause of premature suture fusion, which includes investigation of the craniofacial complex as a system, rather than study of isolated tissues.
Studies of isolated craniosynostosis have shown biomechanical and biochemical influences on the craniofacial phenotype, resulting from both genetic and epigenetic factors. Much less attention has been directed toward the morphology of the brain, despite the interactive nature of the developing skull and developing brain. The aim of this study is to define the morphology of the brain in nonsyndromic unilateral coronal synostosis (UCS) in order to form more complete hypotheses about the cause of craniosynostosis. Landmark coordinate data were collected from 3D magnetic resonance image reconstructions of the brain in a sample of UCS patients and an age-matched morphologically normal cohort. These data were analyzed using Euclidean distance matrix analysis. The results of our study demonstrate that despite the basic similarity of overall shape of the brain and skull in UCS, the effects of craniosynostosis on the brain are not localized to structures immediately adjacent to the fused suture or to the endocranial surface of the skull. Rather, alterations are observed throughout the volume of the brain, with subcortical structures altered in conjunction with cortical changes. These results indicate that the morphological correlates are different for brain and skull and suggest that there is a large degree of independence in the developmental trajectories of the brain and skull.
Models of vertebrate skull evolution stress the coordinated developmental relationship between the skull and the brain that it houses. This study investigates the relationship between altered skull morphology and brain morphology in premature fusion of the cranial sagittal suture (isolated sagittal synostosis; ISS), a condition associated with dysmorphology of both neurocranium and brain. Although the skull displays a more normal shape following reconstructive cranial vault surgery, effects of this surgery on the brain have not been investigated. Landmark coordinate data were collected from three-dimensional magnetic resonance imaging reconstructions of the brain in a sample of ISS patients and an age-matched unaffected cohort. These data were analysed using Euclidean distance matrix analysis (EDMA). Results show that the brain in ISS is dysmorphic preoperatively, displaying a posteriorly directed neural expansion that does not 'worsen' with growth. Postoperatively, the brain in ISS displays a more globular shape overall as compared with the preoperative morphology, but differs from normal in its subcortical morphology.These results show that the ISS brain is altered following neurocranial surgery, but does not more closely approximate that of unaffected individuals. This suggests that although the brain is affected by manipulation of the skull, it retains a growth pattern that is, at least in part, independent of the skull.
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