Skull deformity in infants continues to be a diagnostic and therapeutic challenge. Deformational plagiocephaly is a common and somewhat benign cause of skull deformity in infants that must be distinguished from the more serious craniosynostosis, which occurs alone or as a syndrome. Examining an infant's head from above can help the physician distinguish true lambdoid synostosis from deformational plagiocephaly. In infants with lambdoid synostosis, the posterior bossing is in the parietal area contralateral to the flat part of the head. Deformational plagiocephaly causes frontal bossing ipsilateral to the flat part of the head. In infants with lambdoid synostosis, the ear is displaced posteriorly toward the fused suture. In infants with deformational plagiocephaly, the ear is displaced anteriorly. Isolated sagittal synostosis is the most common type of craniosynostosis. Of the more than 150 craniosynostosis syndromes, Crouzon's disease and Apert's syndrome account for the majority of cases. The diagnosis of craniosynostosis relies on physical examination, plain radiography, and computed tomography. Untreated progressive craniosynostosis leads to inhibition of brain growth, and an increase in intracranial and intraorbital pressure. Infants should be evaluated as soon as they are diagnosed. (+info)
Effects of increased muscle mass on mouse sagittal suture morphology and mechanics.
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The purpose of this study is to test predicted form-function relationships between cranial suture complexity and masticatory muscle mass and biomechanics in a mouse model. Specifically, to test the hypothesis that increased masticatory muscle mass increases sagittal suture complexity, we measured the fractal dimension (FD), temporalis mass, and temporalis bite force in myostatin-deficient (GDF8(-/-)) mice and wild-type CD-1 mice (all male, 6 months old). Myostatin is a negative regulator of muscle mass, and myostatin-deficient mice show a marked increase in muscle mass compared to normal mice. We predicted that increased sagittal suture complexity would decrease suture stiffness. The data presented here demonstrate that increased suture complexity (measured as FD) was observed in a hypermuscular mouse model (GDF8(-/-)) with significantly increased temporalis muscle mass and bite forces. Hypermuscular mice were also found to possess suture connective tissue that was less stiff (i.e., underwent more displacement before failure occurred) when loaded in tension. By decreasing stiffness, suture complexity apparently helps to dissipate mechanical loads within the cranium that are related to chewing. These results suggest that cranial suture connective tissue locally adapts to functional demands of the biomechanical suture environment. As such, cranial sutures provide a novel model for studies in connective tissue mechanotransduction. (+info)
Small mid-Pleistocene hominin associated with East African Acheulean technology.
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Hominin fossils from the African mid-Pleistocene are rare despite abundant Acheulean tools in Africa and apparently African-derived hominins in Eurasia between 1.0 and 0.5 million years ago (Ma). Here we describe an African fossil cranium constrained by 40Ar/39Ar analyses, magnetostratigraphy, and sedimentary features to 0.97 to 0.90 Ma, and stratigraphically associated with Acheulean handaxes. Although the cranium represents possibly the smallest adult or near-adult known between 1.7 and 0.5 Ma, it retains features observed in larger Homo erectus individuals, yet shows a distinct suite of traits indicative of wide population variation in the hominins of this period. (+info)
Posterior fontanelle sonography: an acoustic window into the neonatal brain.
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BACKGROUND AND PURPOSE: Sonographic brain studies are classically performed through the anterior fontanelle, but visualization of posterior supratentorial and infratentorial structures is poor with this approach. Posterior fontanelle sonography is recommended for better assessment of these structures. Our purpose was 1) to determine whether sonography of the brain through the posterior fontanelle (PF) improves visualization of brain lesions when added to the routine anterior fontanelle (AF) approach and 2) to describe standardized PF coronal and sagittal sections. METHODS: In this prospective study (conducted from February 1999 to January 2001), PF sonography was added to AF sonography in 165 consecutive premature neonates with a birth weight of < 2000 g. Sonograms were recorded in digital format for re-evaluation at the end of the study. Lesions were grouped as congenital, infectious, hemorrhagic, or hypoxic-ischemic. The chi2 test for paired data and the kappa coefficient were used to compare diagnoses with AF alone and diagnoses with AF plus PF. RESULTS: PF sonography was performed in 164 of 165 patients. Results were normal in 86 and abnormal in 78. The single posterior fossa malformation detected in this series was best delineated with the PF approach. PF sonography increased the diagnostic rate of grade II hemorrhage by 32%. Cerebellar hemorrhage (two patients) and cerebellar abscesses (one patient) were diagnosed by using the PF approach. PF sonography did not contribute to the diagnosis of periventricular leukomalacia. CONCLUSION: Study of the neonatal brain with the addition of PF sonography afforded greater accuracy in detecting intraventricular hemorrhage compared with AF sonography alone, especially when the ventricle was not dilated. The PF approach better defines posterior fossa malformations. (+info)
A gain-of-function mutation of Fgfr2c demonstrates the roles of this receptor variant in osteogenesis.
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The b and c variants of fibroblast growth factor receptor 2 (FGFR2) differ in sequence, binding specificity, and localization. Fgfr2b, expressed in epithelia, is required for limb outgrowth and branching morphogenesis, whereas the mesenchymal Fgfr2c variant is required by the osteocyte lineage for normal skeletogenesis. Gain-of-function mutations in human FGFR2c are associated with craniosynostosis syndromes. To confirm and extend this evidence, we introduced a Cys342Tyr replacement into Fgfr2c to create a gain-of-function mutation equivalent to a mutation in human Crouzon and Pfeiffer syndromes. Fgfr2c(C342Y/)(+) heterozygote mice are viable and fertile with shortened face, protruding eyes, premature fusion of cranial sutures, and enhanced Spp1 expression in the calvaria. Homozygous mutants display multiple joint fusions, cleft palate, and trachea and lung defects, and die shortly after birth. They show enhanced Cbfa1/Runx2 expression without significant change in chondrocyte-specific Ihh, PTHrP, Sox9, Col2a, or Col10a gene expression. Histomorphometric analysis and bone marrow stromal cell culture showed a significant increase of osteoblast progenitors with no change in osteoclastogenic cells. Chondrocyte proliferation was decreased in the skull base at embryonic day 14.5 but not later. These results suggest that long-term aspects of the mutant phenotype, including craniosynostosis, are related to the Fgfr2c regulation of the osteoblast lineage. The effect on early chondrocyte proliferation but not gene expression suggests cooperation of Fgfr2c with Fgfr3 in the formation of the cartilage model for endochondral bone. (+info)
The role of three-dimensional ultrasound in visualizing the fetal cranial sutures and fontanels during the second half of pregnancy.
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OBJECTIVES: The aim of this study was to evaluate the significance of three-dimensional (3D) ultrasound in visualizing fetal cranial sutures and fontanels and to determine factors that could influence visualization and image quality. METHODS: Serial 3D ultrasound examinations were evaluated for visibility of fetal cranial sutures and fontanels, image quality and possible influencing parameters in the second half of pregnancy. Thirty fetuses were scanned at four different gestational ages providing a data set of 120 cases. RESULTS: Most (82-100%) cranial sutures and fontanels could be visualized with 3D ultrasound. However, the sagittal suture and posterior fontanel were visualized in only 47% and 42%, respectively. Gestational age significantly influenced the visibility of the sutures and fontanels, image quality decreasing with advancing gestational age. CONCLUSIONS: 3D ultrasound can be a reliable technique for visualizing most fetal cranial sutures and fontanels. By performing a sagittal and a transverse scan, most of the sutures and fontanels can be made visible during the second half of pregnancy. Visualization depends on gestational age. (+info)
Delineation of mechanisms and regions of dosage imbalance in complex rearrangements of 1p36 leads to a putative gene for regulation of cranial suture closure.
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Structural chromosome abnormalities have aided in gene identification for over three decades. Delineation of the deletion sizes and rearrangements allows for phenotype/genotype correlations and ultimately assists in gene identification. In this report, we have delineated the precise rearrangements in four subjects with deletions, duplications, and/or triplications of 1p36 and compared the regions of imbalance to two cases recently published. Fluorescence in situ hybridization (FISH) analysis revealed the size, order, and orientation of the duplicated/triplicated segments in each subject. We propose a premeiotic model for the formation of these complex rearrangements in the four newly ascertained subjects, whereby a deleted chromosome 1 undergoes a combination of multiple breakage-fusion-bridge (BFB) cycles and inversions to produce a chromosome arm with a complex rearrangement of deleted, duplicated and triplicated segments. In addition, comparing the six subjects' rearrangements revealed a region of overlap that when triplicated is associated with craniosynostosis and when deleted is associated with large, late-closing anterior fontanels. Within this region are the MMP23A and -B genes. We show MMP23 gene expression at the cranial sutures and we propose that haploinsufficiency results in large, late-closing anterior fontanels and overexpression results in craniosynostosis. These data emphasize the important role of cytogenetics in investigating and uncovering the etiologies of human genetic disease, particularly cytogenetic imbalances that reveal potentially dosage-sensitive genes. (+info)
Single-suture craniosynostosis: a review of neurobehavioral research and theory.
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OBJECTIVE: To review research and theory regarding the neurobehavioral correlates and outcomes of single-suture, or isolated, craniosynostosis in children. METHODS: A critical review of 17 studies of the hypothesized association between isolated craniosynostosis and neurodevelopment. RESULTS: Isolated craniosynostosis is associated with a three- to fivefold increase in risk for cognitive deficits or learning/language disabilities. The causal basis for this association is unclear. No particular calvarial suture (sagittal, metopic, left or right unilateral coronal) has been associated with higher risk of problems. There is little evidence from quasi-experimental studies that cranioplastic surgery prevents or reduces risk of neurobehavioral impairment. CONCLUSIONS: Future studies would benefit from larger samples and larger control groups; measures of specific neuropsychological functions (in addition to global cognition); analyses of neuropsychological status in relation to the severity and cortical impact of synostosis; and an examination of interactions between synostosis and social/family risk factors on neurodevelopment. Routine neurodevelopmental screening of young children with isolated craniosynostosis is recommended. (+info)