Craniosynostosis and altered patterns of fetal TGF-beta expression induced by intrauterine constraint

Cranium growth, patterning and homeostasis

Craniofacial development requires precise spatiotemporal regulation of multiple signaling pathways that crosstalk to coordinate the growth and patterning of the skull with surrounding tissues. Recent insights into these signaling pathways and previously uncharacterized progenitor cell populations have refined our understanding of skull patterning, bone mineralization and tissue homeostasis. Here, we touch upon classical studies and recent advances with an emphasis on developmental and signaling mechanisms that regulate the osteoblast lineage for the calvaria, which forms the roof of the skull. We highlight studies that illustrate the roles of osteoprogenitor cells and cranial suture-derived stem cells for proper calvarial growth and homeostasis. We also discuss genes and signaling pathways that control suture patency and highlight how perturbing the molecular regulation of these pathways leads to craniosynostosis. Finally, we discuss the recently discovered tissue and signaling interactions that integrate skull and cerebrovascular development, and the potential implications for both cerebrospinal fluid hydrodynamics and brain waste clearance in craniosynostosis.

Update in Management of Craniosynostosis

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the craniofacial dysmorphology of craniosynostosis, and the variation of each type. 2. Identify the functional concerns and learn the rationale behind timing of operative intervention. 3. Approach each dysmorphology critically and identify the operative intervention needed to improve form and function 4. Understand and address the specific issues related to syndromic craniosynostosis and be able to delineate management plan.

SUMMARY

Craniosynostosis is a condition in which premature fusion of one or more cranial sutures lead to abnormal head shape and growth restriction of the brain. Nonsyndromic craniosynostosis occurs in isolation, and usually involves a single suture, whereas syndromic craniosynostosis may involve multiple sutures and is associated with extracraniofacial findings. Although surgical management can be similar, the treatment plan must take into consideration issues specific to the syndromes. This article aims to provide a concise overview of the authors' current understanding regarding the presentation, treatment principle, surgical option, and debates in craniosynostosis.

Management of Lambdoid Craniosynostosis: A Comprehensive and Systematic Review

BACKGROUND

Craniosynostosis is a condition characterized by the premature fusion of 2 or more skull bones. Craniosynostosis of the lambdoid suture is one of the rarest forms, accounting for 1-4% of all craniosynostoses. Documented cases are separated into simple (single suture), complex (bilateral), and associated with adjacent synostoses ("Mercedes Benz" Pattern) or syndromes (i.e., Crouzon, Sathre-Chotzen, Antley-Bixler). This condition can manifest phenotypic deformities and neurological sequelae that can lead to impaired cognitive function if improperly treated or left undiagnosed. Preferred surgical techniques have varied over time but all maintain the common goals of establishing proper head shape and preventing of complications that could contribute to aforementioned sequelae.

SUMMARY

This comprehensive review highlights demographic distributions, embryological development, pathogenesis, clinical presentation, neurological sequelae, radiologic findings, surgical techniques, surgical outcomes, and postoperative considerations of patients with lambdoid craniosynostosis presentation. In addition, a systematic review was conducted to explore the operative management of lambdoid craniosynostosis using PubMed, Embase, and Scopus databases, with 38 articles included after screening. Key Messages: Due to a low volume of published cases, diagnosis and treatment can vary. Large overlap in presentation can occur in patients that display lambdoid craniosynostosis and posterior plagiocephaly, furthering the need for comprehensive analysis. Possessing the knowledge and tools to properly assess patients with lambdoid craniosynostosis will allow for more precise care and improved outcomes.

Sagittal Synostosis and Its Association With Cognitive, Behavioral, and Psychological Functioning: A Meta-analysis

IMPORTANCE

Findings on the cognitive, behavioral, and psychological functioning of individuals with sagittal synostosis (SS) are highly disparate, limiting their clinical utility.

OBJECTIVE

To identify and review research on individuals with SS and to determine whether, and to what extent, they experience cognitive, behavioral, and psychological difficulties compared with their healthy peers or normative data for each measure.

DATA SOURCES

PubMed, Scopus, Embase, and PsycINFO were searched through January 2021 with no date restrictions. Scopus citation searches and manual checks of the reference lists of included studies were conducted.

STUDY SELECTION

Studies included participants of any age who had received a diagnosis of single-suture (isolated or nonsyndromic) SS or scaphocephaly and who had been assessed on cognitive, behavioral, and psychological outcomes.

DATA EXTRACTION AND SYNTHESIS

Data were independently extracted by 2 reviewers. Case-control outcomes (individuals with SS vs healthy peers or normative data) were compared using random-effects models with 3 effect sizes calculated: weighted Hedges g (gw), odds ratios (ORs), and mean prevalence rates. This study follows the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines.

MAIN OUTCOMES AND MEASURES

Findings were categorized by surgical status (conservatively managed, presurgery, postsurgery, or combined); domain (eg, general cognition); type of cognitive, behavioral, or psychological measure (objective or subjective); and source of comparison data (peers or normative data).

RESULTS

Data from 32 studies, involving a pooled sample of 1422 children and adults with SS (mean [SD] age at assessment, 5.7 [6.6] years; median [interquartile range] age, 3.3 [0.5-10.3] years), were analyzed. Data on sex were available for 824 participants, and 642 (78%) were male. Individual study results varied substantially. Objective tests identified significant moderate group differences on 3 of 16 examined domains: presurgical motor functioning (3 studies; gw = -0.42; 95% CI, -0.67 to -0.18; P < .001), postsurgical short-term memory (2 studies; gw = -0.45; 95% CI, -0.72 to -0.17; P < .001), and postsurgical visuospatial ability (6 studies; gw = 0.31; 95% CI, 0.18 to 0.44; P < .001). Prevalence estimates and ORs varied widely, with 15 studies showing prevalence estimates ranging from 3% to 37%, and 3 studies showing ORs ranging from 0.31 (95% CI, 0.01 to 6.12) for processing speed in the conservatively managed sample to 4.55 (95% CI, 0.21 to 98.63) for postsurgical visuospatial abilities.

CONCLUSIONS AND RELEVANCE

In this meta-analysis, findings for the functioning of participants with SS were highly disparate and often of low quality, with small samples sizes and control groups rarely recruited. Nonetheless, the findings suggest that some individuals with SS experience negative outcomes, necessitating routine assessment.

Coronal and lambdoid suture evolution following total vault remodeling for scaphocephaly

OBJECTIVE

Different types of surgical procedures are utilized to treat craniosynostosis. In most procedures, the fused suture is removed. There are only a few reports on the evolution of sutures after surgical correction of craniosynostosis. To date, no published study describes neosuture formation after total cranial vault remodeling. The objective of this study was to understand the evolution of the cranial bones in the area of coronal and lambdoid sutures that were removed for complete vault remodeling in patients with sagittal craniosynostosis. In particular, the investigation aimed to confirm the possibility of neosuture formation.

METHODS

CT images of the skulls of children who underwent operations for scaphocephaly at the Hôpital Femme Mère Enfant, Lyon University Hospital, Lyon, France, from 2004 to 2014 were retrospectively reviewed. Inclusion criteria were diagnosis of isolated sagittal synostosis, age between 4 and 18 months at surgery, and availability of reliable postoperative CT images obtained at a minimum of 1 year after surgical correction. Twenty-six boys and 11 girls were included, with a mean age at surgery of 231.6 days (range 126-449 days). The mean interval between total vault reconstruction and CT scanning was 5.3 years (range 1.1-12.2 years).

RESULTS

Despite the removal of both the coronal and lambdoid sutures, neosutures were detected on the 3D reconstructions. All combinations of neosuture formation were seen: visible lambdoid and coronal neosutures (n = 20); visible lambdoid neosutures with frontoparietal bony fusion (n = 12); frontoparietal and parietooccipital bony fusion (n = 3); and visible coronal neosutures with parietooccipital bony fusion (n = 2).

CONCLUSIONS

This is the first study to report the postoperative skull response after the removal of normal patent sutures following total vault remodeling in patients with isolated sagittal synostosis. The reappearance of a neosuture is rather common, but its incidence depends on the type of suture. The outcome of the suture differs with the incidence of neosuture formation between these transverse sutures. This might imply genetic and functional differences among cranial sutures, which still have to be elucidated.

Spatial regulation of gene expression in nonsyndromic sagittal craniosynostosis

OBJECTIVECranial suture patterning and development are highly regulated processes that are not entirely understood. While studies have investigated the differential gene expression for different sutures, little is known about gene expression changes during suture fusion. The aim of this study was to examine gene expression in patent, fusing, and fused regions along sagittal suture specimens in nonsyndromic craniosynostosis patients.METHODSSagittal sutures were collected from 7 patients (average age 4.5 months) who underwent minimally invasive craniotomies at the Children's Hospital of Richmond at VCU under IRB approval. The sutures were analyzed using micro-CT to evaluate patency. The areas were classified as open, fusing, or fused and were harvested, and mRNA was isolated. Gene expression for bone-related proteins, osteogenic and angiogenic factors, transforming growth factor-β (TGF-β) superfamily, and Wnt signaling was analyzed using quantitative polymerase chain reaction and compared with normal sutures collected from fetal demise tissue (control).RESULTSMicro-CT demonstrated that there are variable areas of closure along the length of the sagittal suture. When comparing control samples to surgical samples, there was a significant difference in genes for Wnt signaling, TGF-β, angiogenic and osteogenic factors, bone remodeling, and nuclear rigidity in mRNA isolated from the fusing and fused areas of the sagittal suture compared with patent areas (p < 0.05).CONCLUSIONSIn nonsyndromic sagittal craniosynostosis, the affected suture has variable areas of being open, fusing, and fused. These specific areas have different mRNA expression. The results suggest that BMP-2, FGFR3, and several other signaling pathways play a significant role in the regulation of suture fusion as well as in the maintenance of patency in the normal suture.

Squamosal Craniosynostosis: Defining the Phenotype and Indications for Surgical Management

BACKGROUND

Squamosal craniosynostosis is seldom reported in the craniofacial literature. Given that this is an uncommon diagnosis, phenotype and management remain unclear. The authors present a case series and review the literature to define the phenotype and management of these patients.

METHODS

We retrospectively reviewed 7 patients from our institution and systematically reviewed all published cases of squamosal craniosynostosis. Demographics, medical history, imaging, clinical presentation, subsequent workup, and treatment were examined and analyzed.

RESULTS

A comprehensive review of the literature yielded a total of 31 cases (including our new series) of squamosal craniosynostosis. Average age of presentation was 25.3 months, 52% of female patients, 74% of cases with bilateral squamosal involvement, 44% syndromic, 39% isolated squamosal (vs 61% multisutural). Overall, 56% of cases were handled surgically, whereas 44% were managed conservatively. Thirty-three percent of surgical cases required multiple operations. One patient with isolated bilateral squamosal craniosynostosis developed elevated intracranial pressure, requiring cranial vault remodeling.

CONCLUSIONS

Squamosal craniosynostosis frequently presents in a delayed fashion with nonsyndromic, bilateral involvement. In isolated bilateral squamosal cases, the associated phenotype is frontal prominence, occipital flattening, scaphocephalic tendency (low-end normocephalic cranial index), and superior parietal cornering. Evaluation of clinical signs and computed tomography imaging guides management, as evidence of increased intracranial pressure may indicate need for cranial vault expansion. Although previous literature suggests that nonsyndromic cases are nonsurgical, the majority of cases reviewed required surgical intervention, including our case of isolated bilateral squamosal craniosynostosis. We recommend vigilant management in patients with squamosal craniosynostosis, even those with isolated squamosal involvement.

Application of Laser Capture Microdissection to Craniofacial Biology: Characterization of Anatomically Relevant Gene Expression in Normal and Craniosynostotic Rabbit Sutures

OBJECTIVE

Fusion of the cranial sutures is thought to depend on signaling among perisutural tissues. Mapping regional variations in gene expression would improve current models of craniosynostosis. Laser capture microdissection (LCM) isolates discrete cell populations for gene expression analysis. LCM has rarely been used in the study of mineralized tissue. This study sought to evaluate the potential use of LCM for mapping of regional gene expression within the cranial suture.

DESIGN

Coronal sutures were isolated from 10-day-old wild-type and craniosynostotic (CS) New Zealand White rabbits, and LCM was used to isolate RNA from the sutural ligament (SL), osteogenic fronts (OF), dura mater, and periosteum. Relative expression levels for Fibroblast Growth Factor 2 (FGF2), Fibroblast Growth Factor Receptor 2 (FGFR2), Transforming Growth Factor Beta 2 (TGFβ-2), Transforming Growth Factor Beta 3 (TGFβ-3), Bone Morphogenetic Protein 2 (BMP-2), Bone Morphogenetic Protein 4 (BMP-4), and Noggin were determined using quantitative real-time PCR.

RESULTS

A fivefold increase in TGFβ2 expression was detected in the CS SL relative to wild type, whereas 152-fold less TGFβ-3 was detected within the OF of CS animals. Noggin expression was increased by 10-fold within the CS SL, but reduced by 13-fold within the CS dura. Reduced expression of FGF2 was observed within the CS SL and dura, whereas increased expression of FGFR2 was observed within the CS SL. Reduced expression of BMP-2 was observed in the CS periosteum, and elevated expression of BMP-4 was observed in the CS SL and dura.

CONCLUSIONS

LCM provides an effective tool for measuring regional variations in cranial suture gene expression. More precise measurements of regional gene expression with LCM may facilitate efforts to correlate gene expression with suture morphogenesis and pathophysiology.

Congenital muscular torticollis concurrent with sagittal synostosis: a case report

Congenital muscular torticollis (CMT) and craniosynostosis are diseases that cause plagiocephaly and craniofacial asymmetry in children. In our literature review, we did not find any report of concurrent manifestation of CMT and craniosynostosis. A 41-month-old boy visited our hospital with left torticollis, right laterocollis, and craniofacial asymmetry as the main findings. During clinical examination, prominent right sternocleidomastoid muscle and limited range of motion of the neck were noted, and right CMT was confirmed by magnetic resonance imaging of the neck. Three-dimensional computed tomography of the skull, which was conducted due to the unusual appearance of the skull with a large head circumference, mild brachycephaly, as well as left plagiocephaly, revealed premature closure of the sagittal suture. Thus, we report the first case that showed concurrence of CMT and sagittal synostosis. We recommend that concurrently manifested craniosynostosis needs to be examined if the subject with CMT displays unusual craniofacial asymmetry to a greater extent than deformational plagiocephaly.

Clinical characteristics and surgical decision making for infants with metopic craniosynostosis in conjunction with other congenital anomalies

Background:

Metopic craniosynostosis can occur in isolation or in conjunction with other congenital anomalies. The surgical decision making and outcomes between these 2 groups are analyzed.

Methods:

A retrospective review of all children evaluated in the craniofacial clinic at Seattle Children’s Hospital for metopic craniosynostosis between 2004 and 2009 was performed. Physical examination and CT scan characteristics were analyzed as were the treatment decisions and surgical outcomes.

Results:

From 2004 to 2009, 282 patients were evaluated and 100 were determined to have metopic craniosynostosis. Of these, 19 patients were found to have additional congenital anomalies. Review of these patients’ CT scans revealed 13 with classic trigonencephaly, 3 with microcephaly, and 3 with narrow frontal bones, abnormal orbits, and small anterior fossa. Patients (90%) with isolated metopic craniosynostosis underwent cranial vault expansion, whereas only 63% of the complex group did so. The complex metopic group had a longer hospital stay (5 d vs 3.4 d), more intraoperative complications, and required more repeat surgery.

Conclusion:

Patients with metopic craniosynostosis and additional anomalies require special consideration when deciding upon surgical intervention and should be cared for by a multidisciplinary team to address their additional needs.

Craniocerebral disproportion: a topical review and proposal toward a new definition, diagnosis, and treatment protocol

INTRODUCTION

At some point in their lives, patients previously shunted for hydrocephalus may experience chronic, debilitating headaches, despite the fact that their shunts are functioning properly. Previously published reports have suggested that a subset of these patients may be suffering from an iatrogenic craniocerebral disproportion (CCD) and, therefore, may benefit from procedures that expand the available intracranial space. A unified definition of this disorder, however, is lacking.

DISCUSSION

Here, the authors chart the history (including historical terminology) of CCD, review its incidence, describe its signs, symptoms, and associated radiologic findings, and expound upon its pathophysiology. Next, a concise clinical definition of CCD based on the temporal correlation of headaches with the appearance of plateau waves on intracranial pressure (ICP) monitoring is proposed. The authors conclude with a discussion of the various therapeutic strategies employed previously to treat this disorder and present their individualized treatment strategy based upon the simultaneous utilization of ICP monitors and gradual external cranial vault expansion.

Frank-ter Haar syndrome associated with sagittal craniosynostosis and raised intracranial pressure

BACKGROUND

Frank-ter Haar syndrome is a rare disorder associated with skeletal, cardiac, ocular and craniofacial features including hypertelorism and brachycephaly. The most common underlying genetic defect in Frank-ter Haar syndrome appears to be a mutation in the SH3PXD2B gene on chromosome 5q35.1. Craniosynostosis, or premature fusion of the calvarial sutures, has not previously been described in Frank-ter Haar syndrome.

CASE PRESENTATION

We present a family of three affected siblings born to consanguineous parents with clinical features in keeping with a diagnosis of Frank-ter Haar syndrome. All three siblings have a novel mutation caused by the deletion of exon 13 of the SH3PXD2B gene. Two of the three siblings also have non-scaphocephalic sagittal synostosis associated with raised intracranial pressure.

CONCLUSION

The clinical features of craniosynostosis and raised intracranial pressure in this family with a confirmed diagnosis of Frank-ter Haar syndrome expand the clinical spectrum of the disease. The abnormal cranial proportions in a mouse model of the disease suggests that the association is not coincidental. The possibility of craniosynostosis should be considered in individuals with a suspected diagnosis of Frank-ter Haar syndrome.

The role of vertebrate models in understanding craniosynostosis

BACKGROUND

Craniosynostosis (CS), the premature fusion of cranial sutures, is a relatively common pediatric anomaly, occurring in isolation or as part of a syndrome. A growing number of genes with pathologic mutations have been identified for syndromic and nonsyndromic CS. The study of human sutural material obtained post-operatively is not sufficient to understand the etiology of CS, for which animal models are indispensable.

DISCUSSION

The similarity of the human and murine calvarial structure, our knowledge of mouse genetics and biology, and ability to manipulate the mouse genome make the mouse the most valuable model organism for CS research. A variety of mouse mutants are available that model specific human CS mutations or have CS phenotypes. These allow characterization of the biochemical and morphological events, often embryonic, which precede suture fusion. Other vertebrate organisms have less functional genetic utility than mice, but the rat, rabbit, chick, zebrafish, and frog provide alternative systems in which to validate or contrast molecular functions relevant to CS.

Role of RANK-RANKL-OPG axis in cranial suture homeostasis

Craniosynostosis is a significant disorder affecting 1 in 2500 live births worldwide. Although a large body of work has focused on dural regulation and the contributions of molecular mediators such as fibroblast growth factor, bone morphogenetic protein, and transforming growth factor β, minimal attention has been directed toward osteoclast function in cranial suture biology. Receptor activator of nuclear factor κB (RANK) is an essential mediator of osteoclastogenesis and osteoclast activation. In this study, physiologic fusion of posterior frontal sutures in murine development correlated with decreasing protein expression of RANK in comparison to age-matched coronal and sagittal sutures via immunohistochemical survey. However, RANK mRNA did not exhibit a similar pattern suggesting that RANK is regulated at the protein level. Fused cranial sutures in nonsyndromic craniosynostotic children also showed decreased levels of RANK staining in immunohistochemistry in comparison to patent sutures from the same patients. Immunohistochemistry with a RANK ligand antibody did not show differences in fused or patent sutures. Moreover, RANK knockdown in calvarial strip suture cultures displayed increased bone density specifically in the suture line after infection with small interfering RANK viruses. Cranial suture biology, similar to bone biology in general, likely depends on a complex interplay between osteoblasts and osteoclasts. We now report a temporospatial correlation between RANK expression and suture morphology that suggests that osteoclast activity is important in maintenance of cranial suture patency in normal physiology and disease. Furthermore, RANK downregulation promoted suture fusion establishing a causal relationship between the presence of RANK and patency.

Effects of uterine cervix constriction on Wistar rats

PURPOSE

To verify if uterine cerclage can induce craniosynostosis or any cranial deformity in new born Wistar rats.

METHODS

One pregnant female Wistar rat underwent laparotomy on day 18 of gestation and the uterus cervix was closed with a 3-0 nylon suture to avoid delivery, that occurs normally on the 21 day. The suture was released after 48 hours beyond the normal gestation period. The female rat delivered 11 pups. Six surviving rats from the delivery (group A - constrained group). Two rats were born from another mother and in the same age were used as control group (group B - 2 nonconstrained controls) were allowed to grow. They were sacrificed 1.2 years after their birth all the eight animals. Linear measurement, routine histology and computed tomography of the skull were performed at the time of their death to evaluate the cranial asymmetries by measurements of the anatomical landmarks of the craniofacial skeleton of the rats on the two groups and compared then.

RESULTS

We did not observe statistically significant differences in any of the compared measurements (p>0.05) obtained through the morphologic and radiologic methods. Histologic examinations did not reveal any sign of premature fusion or suture imbrications. Critical decrease in longitudinal body size was noticed as the limbs too in all the animals of group A.

CONCLUSION

Constriction of uterine cervix leads to fetus suffering, even death for a few animals, associated to small body size, but not to craniosynostosis.

Paracrine interaction between adipose-derived stromal cells and cranial suture-derived mesenchymal cells

BACKGROUND

Adipose-derived stromal cells are a potential cell source for the successful healing of skeletal defects. In this study, the authors sought to investigate the potential for cranial suture-derived mesenchymal cells to promote the osteogenic differentiation of adipose-derived stromal cells. Various reports have previously examined the unique in vitro attributes of suture-derived mesenchymal cells; this study sought to extend those findings.

METHODS

Suture-derived mesenchymal cells were isolated from wild-type mice (n = 30) from both fusing posterofrontal and patent sagittal sutures. Cells were placed in Transwell inserts with human adipose-derived stromal cells (n = 5 patients) with osteogenic differentiation medium with or without recombinant Noggin (10 to 400 ng/ml). Specific gene expression of osteogenic markers and Hedgehog pathway were assayed; standard osteogenic assays (alkaline phosphatase and alizarin red staining) were performed. All assays were performed in triplicate.

RESULTS

Both posterofrontal and sagittal suture-derived mesenchymal cells induced osteogenic differentiation of adipose-derived stromal cells (p < 0.05). Posterofrontal suture-derived mesenchymal cells induced adipose-derived stromal cell osteogenesis to a greater degree than sagittal suture-derived mesenchymal cells (p < 0.05). This was accompanied by an increase in bone morphogenetic protein expression (p < 0.05). Finally, recombinant Noggin mitigated the pro-osteogenic effects of co-culture accompanied by a reduction in Hedgehog signaling (p < 0.05).

CONCLUSIONS

Suture-derived mesenchymal cells secrete paracrine factors that induce osteogenic differentiation of multipotent stromal cells (human adipose-derived stromal cells). Cells derived from the fusing posterofrontal suture do this to a significantly greater degree than cells from the patent sagittal suture. Enhanced bone morphogenetic protein and Hedgehog signaling may underlie this paracrine effect.

Is isolated sagittal synostosis an isolated condition?

BACKGROUND

Scaphocephaly is the most common type of craniosynostosis. In the medical literature, there is little information about the association of scaphocephaly and other congenital anomalies.

PATIENTS AND METHODS

To determine the prevalence of genetic anomalies in scaphocephaly patients, a retrospective review of the medical charts of 30 consecutive patients was performed. A questionnaire was sent to parents to evaluate demographics.

RESULTS

The male-female ratio was 2:1, 22% of patients were born at less than 37 weeks gestation, and 4% of the patients were twins. Nineteen percent of mothers smoked during pregnancy, and 23% of the mothers consumed alcohol during pregnancy. Eighteen of the 30 patients visited the department of clinical genetics, whereas the other patients were examined by a pediatrician. Genetic analysis was performed on 8 patients. A genetic mutation on the FGFR-2 gene was found in 1 patient with Gorlin-Goltz syndrome. Except for the basal cell carcinomas and the sagittal synostoses, this patient had no other congenital anomalies. Two other patients had congenital malformations of the heart and kidneys.

CONCLUSIONS

This study demonstrates the low incidence of associated congenital anomalies and scaphocephaly. Associated factors of isolated sagittal synostosis are preterm birth and male sex.

Transforming growth factor-beta1 stimulates chondrogenic differentiation of posterofrontal suture-derived mesenchymal cells in vitro

BACKGROUND

Evidence from animal studies has associated transforming growth factor (TGF)-beta signaling with both normal and premature cranial suture fusion. However, the mechanisms whereby this pleiotropic cytokine mediates suture fusion remain uncertain. The authors established cultures of suture-derived mesenchymal cells from normally fusing (posterofrontal) and patent (sagittal) sutures and examined the in vitro effects of TGF-beta1 on these distinct cell populations.

METHODS

Skulls were harvested from 80 5-day-old mice. Posterofrontal and sagittal sutures were dissected, and cultures of suture-derived mesenchymal cells were established. The mitogenic, osteogenic, and chondrogenic effects of recombinant TGF-beta1 were then assessed on posterofrontal and sagittal suture-derived mesenchymal cells (1 to 10 ng/ml). Quantitative real-time polymerase chain reaction was used to examine the effects of TGF-beta1 on gene expression.

RESULTS

TGF-beta1 significantly decreased proliferation of both posterofrontal and sagittal suture-derived mesenchymal cells, by bromodeoxyuridine incorporation assays (n = 6). TGF-beta1 also inhibited osteogenesis in both suture-derived mesenchymal cells determined by alkaline phosphatase activity and mineralization (n = 3 for all assays). During chondrogenic differentiation, TGF-beta1 markedly increased expression of chondrocyte-specific gene markers in posterofrontal suture-derived mesenchymal cells (Sox9, Col II, Aggrecan, and Col X) (p <or= 0.05). In contrast, TGF-beta1 did not increase chondrocyte-specific gene expression in sagittal suture-derived mesenchymal cells (n = 3).

CONCLUSIONS

Posterofrontal suture-derived mesenchymal cells retain significant capability for both osteogenic and chondrogenic differentiation in vitro. TGF-beta1 induces in vitro chondrogenesis in posterofrontal but not sagittal suture-derived mesenchymal cells. Future studies will focus on elucidating the mechanisms whereby TGF-beta signaling mediates chondrogenesis in posterofrontal suture-derived mesenchymal cells.

Familial lambdoid craniosynostosis between father and son

Lambdoid craniosynostosis is an uncommon condition, with an incidence of 1 per 33,000 live births. Its etiopathology remains controversial. Although many forms of syndromic and nonsyndromic craniosynostosis demonstrate an inherited pattern, few articles have reported lambdoid craniosynostosis in the same family. In this article, we report lambdoid synostosis in a father and son. A case review is performed. A full-term male infant was delivered by cesarean delivery because of failure to progress. He presented at 3 years of age with right unilateral lambdoid craniosynostosis with facial asymmetry and lateral deviation of his jaw, with occlusal abnormality. At presentation, the father reported skull surgery during his infancy for unilateral lambdoid craniosynostosis. Review of the computed tomographic scan of the child demonstrated a plagiocephalic appearance of the calvarium with frontal bossing and a fusion of the lambdoid suture on the right sides. The brain parenchyma showed no abnormality. The review of his father's surgical record from 33 years ago and of his computed tomographic scan ordered by our team confirmed the diagnosis of previous lambdoid craniosynostosis. Only 2 previous cases of familial isolated lambdoid craniosynostosis have been previously described in literature. Although the genetic basis has been established for many types of craniosynostosis, the etiopathogenesis of isolated lambdoid synostosis has not yet been established. We report the third case of inherited unilateral lambdoid craniosynostosis. The genetic pathogenesis of lambdoid craniosynostosis will be discussed.

Differential effects of TGF-beta isoforms on murine fetal dural cells and calvarial osteoblasts

BACKGROUND

Proteins within the transforming growth factor (TGF)-beta family play a central role in both normal and pathologic calvarial morphogenesis. Previous work has suggested differential functions of the TGF-beta isoforms in these processes. Little is known, however, about effects of TGF-betas on the underlying dura. Furthermore, studies on the effects of TGF-beta isoforms on osteoblasts have been conflicting. The purpose of this study was to determine the effect of TGF-beta isoforms, specifically TGF-beta1 and TGF-beta3, on fetal calvarial osteoblast and dural cell differentiation, proliferation, and apoptosis.

METHODS

Primary cultures of fetal calvarial osteoblasts and dural cells were established from embryonic day-18 CD-1 mice. Cells were treated for 48 hours with TGF-beta1 or TGF-beta3. Northern blot analysis, cell counts, and apoptosis assays were performed.

RESULTS

In dural cells, TGF-beta1 stimulated the expression of early osteodifferentiation genes and resulted in a slight decrease in cell number and no effect on apoptosis. Similar results were observed in osteoblasts. TGF-beta3 had little or no effect on the genes studied in both cell types but resulted in increased apoptosis and concomitant decreases in cell number in both cell types.

CONCLUSIONS

This study demonstrates that dural cells respond to TGF-beta and that this response is isoform-specific. TGF-beta1 stimulates osteodifferentiation of previously uncommitted cells in the dura. It also stimulates early events in bone matrix deposition and has little effect on late markers of bone differentiation in osteoblasts and dural cells. Both isoforms result in decreases in cell number. TGF-beta3 results in greater decreases in cell number and isoform-specific stimulation of apoptosis in both dural cells and calvarial osteoblasts.

Cranial Suture Response to Stress: Expression Patterns of Noggin and Runx2

BACKGROUND

Current theory on normal cranial suture fusion entrusts the dura with the regulatory role. Studies suggest that the dura responds to stress with changes in gene expression. Noggin (bone morphogenetic protein inhibitor) expression is decreased in normal (rat and mouse) cranial suture fusion, but its role in craniosynostosis and the response to stress has not been studied.

METHODS

Posterior frontal (fusing) and sagittal (patent) rat cranial sutures were held static, oscillated, or distracted for 10 days in an organ culture microdistraction device beginning at 5 days of age (n = 30 sutures, or 10 sutures per group). The percentage of fusion equaled the score received for bony closure. Noggin, Runx2, and alkaline phosphatase expression was localized by immunohistochemistry for all groups.

RESULTS

Both the posterior frontal and sagittal sutures demonstrated a significant (p < 0.05) increase in fusion percentage with oscillation relative to the static control. Noggin was not expressed in the fusing posterior frontal suture but was expressed in the normally patent sagittal suture. Conversely, Runx2 was expressed in the posterior frontal suture but not in the sagittal suture. However, when a mechanical stress was applied, both the posterior frontal and sagittal sutures expressed Runx2 but not Noggin, as in the static fusing suture.

CONCLUSIONS

The application of mechanical stress to cranial sutures results in fusion of both the posterior frontal suture and the normally patent sagittal suture. Runx2 is expressed but Noggin is not expressed. Thus, mechanical stress influences sutural fusion and may play a role in craniosynostosis.

Zygomaticotemporal synostosis: a rare cause of progressive facial asymmetry

Cranial synostosis is relatively common; however, premature closure of a facial suture is remarkably rare. We describe an adolescent male with zygomaticotemporal synostosis that manifested as progressive midfacial and orbital asymmetry, angulation of the cranial base, and nasal deviation. To our knowledge, this is the first description of this anomaly in the literature.

Postoperative Anti-Tgf-β2 Antibody Therapy Improves Intracranial Volume and Craniofacial Growth in Craniosynostotic Rabbits

Postoperative resynostosis and secondary craniofacial growth abnormalities are common sequelae after craniofacial surgery. It has been suggested that an overexpression of transforming growth factor-beta2 (Tgf-beta2) may be related to craniosynostosis and contribute to postoperative resynostosis. Interference with Tgf-beta2 function using neutralizing antibodies may inhibit resynostosis and improve postoperative craniofacial growth; the present study was designed to test this hypothesis. Twenty-nine New Zealand white rabbits with bilateral coronal suture synostosis were used: 1) suturectomy controls (n=9); 2) suturectomy with nonspecific, control IgG antibody (n=9); and 3) suturectomy with anti-Tgf-beta2 antibody (n=11). At 10 days of age, a 3 mm x 15-mm coronal suturectomy was performed. The sites in groups 2 and 3 were immediately filled with 0.1 cc of a slow resorbing collagen gel mixed with either IgG (100 microg/suture) or anti-Tgf-beta2 (100 microg/suture). Three-dimensional computed tomography scan reconstructions of the skulls and cephalographs were obtained at 10, 25, 42, and 84 days of age. Computed tomography scan data revealed patent suturectomy sites and significantly (P<0.05) greater intracranial volumes by 84 days of age in rabbits treated with anti-Tgf-beta2 compared with controls. Cephalometric analysis revealed significant (P<0.05) differences in craniofacial, cranial vault, and cranial base growth by 84 days of age in rabbits treated with anti-Tgf-beta2 compared with controls. These data support the initial hypothesis that interference with Tgf-beta2 function inhibited postoperative resynostosis and improved cranial vault growth in this rabbit model. Thus, this biologically based therapy may be a potential surgical adjunct in the treatment of infants with craniosynostosis.

Expression of Indian Hedgehog, BMP-4 and Noggin in Craniosynostosis Induced by Fetal Constraint

Indian Hedgehog (Ihh), bone morphogenetic protein (BMP), and its antagonist Noggin play an important regulatory role in bone formation. We used an animal model to study the role of these molecules in craniosynostosis induced by fetal constraint. C57Bl/6 mice underwent cervical cerclage on the 18th day of gestation, and their pups were harvested 48 and 72 hours beyond the normal gestational period. Constrained and control calvariae were examined for expression of BMP-4, Noggin, Histone H4C, Ihh, Sonic Hedgehog (Shh), and Patched 1 (Ptch1), one of the Hh transcriptional target molecules/Hh receptors. Constraint-induced suture fusion was associated with decreased expression of Ihh and Noggin, whereas BMP-4 was expressed in both control and constrained sutures. Ptch1 colocalized with Ihh-positive osteogenic cells at the osteogenic fronts, but not with Shh transcripts, suggesting that Ihh, but not Shh, regulates Ptch1 expression in cranial suture development. Histone H4C was preferentially expressed in Ihh-positive cells, indicating that Ihh may regulate osteogenic cell proliferation at the osteogenic fronts. These results suggest a role for Ihh and Noggin signaling in constraint-induced craniosynostosis.

Case report of optic atrophy in pansynostosis: an unusual presentation of scalp edema from hair braiding

Pansynostosis (fusion of all cranial sutures) and optic atrophy were found as incidental CT scan and ophthalmological findings in an 8-year-old who presented to the emergency room with scalp edema from tight 'cornrow' hair braiding. Cranial vault expansion was successfully performed. Ophthalmological problems have stabilized but have not reversed. Late presentation of craniosynostosis and the pathophysiology of secondary optic atrophy are discussed.

Brain morphology in nonsyndromic unicoronal craniosynostosis

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.

Expression and Possible Mechanisms of Regulation of BMP3 in Rat Cranial Sutures

BACKGROUND

Clinical genetics data and investigative studies have contributed greatly to our understanding of the role of numerous genes in craniosynostosis. Recent studies have introduced antagonists of osteogenesis as potential key regulators of suture fusion and patency. The authors investigated the expression pattern of the bone morphogenetic protein antagonist BMP3 in rat cranial sutures and the factors regulating its expression in vitro.

METHODS

Microarray analysis was performed on rat posterior frontal and sagittal cranial sutures at 5, 10, 15, 20, and 30 days of life (n = 30 per group). Gene expression was confirmed using quantitative real-time reverse transcriptase polymerase chain reaction. Regulation of BMP3 expression was determined using primary rat calvarial osteoblasts stimulated with recombinant human fibroblast growth factor 2 or recombinant human transforming growth factor beta1, or cultured with primary rat nonsuture dura mater. Gene expression was quantified with quantitative real-time reverse transcriptase polymerase chain reaction.

RESULTS

BMP3 expression in the posterior frontal suture decreased over the time course analyzed, whereas it increased in the sagittal suture. Notably, BMP3 expression was higher in the patent sagittal suture during the window of posterior frontal suture fusion. Stimulation of osteoblasts with recombinant human fibroblast growth factor 2 led to a rapid and sustained suppression of BMP3 expression (85 percent, p < 0.01) when compared with controls. Co-culture with dural cells decreased BMP3 mRNA by 50 percent compared with controls (p < 0.01).

CONCLUSIONS

BMP3 is expressed in rat cranial sutures in a temporal pattern suggesting involvement in cranial suture patency and fusion. Furthermore, BMP3 is regulated in calvarial osteoblasts by recombinant human fibroblast growth factor 2 and by paracrine signaling from dura mater. These data add to our knowledge of the role of osteogenic antagonists in cranial suture biology.

Concordant contralateral lambdoidal synostosis in dizygotic twins

Twin studies have been widely used to investigate genetic versus environmental causality of malformations. While there are numerous reports of concordant sutural fusions in syndromic twins, there are few cases in siblings with nonsyndromic single suture synostosis. Lambdoidal synostosis has no clear genetic etiology. Discordant synostosis has been reported in one monozygotic twin; there is also an unsubstantiated report of concordance in dizygotic twins. We describe dizygotic twins concordant for contralateral lambdoidal synostosis. Mutational analysis for FGFR 1,2,3 was negative. Given the low incidence, absence of reported inheritability, and lack of documented concordance in monozygotic twins, the pathogenesis of isolated lambdoidal fusion can only be ascribed to stochastic influences.

Malformations of the axial skeleton in the museum Vrolik: II: craniosynostoses and suture-related conditions

The Museum Vrolik collection of anatomical specimens in Amsterdam, The Netherlands, comprises over 5,000 specimens of human and animal anatomy, embryology, pathology, and congenital anomalies. Recently, we rediagnosed a subset of the collection comprising dried infantile, juvenile, and adult human skulls with congenital and acquired conditions. On external examination and additional radiography, we found 58 skulls with craniosynostosis (CS) involving one or more sutures and 40 skulls with a presumed suture related condition. Most of these were part of the material collected and described by Louis Bolk (1866-1930). Analysis of his observations suggests that skull deformation because of premature suture closure depends not only on the identity of the sutures involved but also on the timing and progression of their closure and the extent of their involvement. Moreover, premature closure of the sagittal suture after 3-6 years of age appeared to be much more common than expected because it is not accompanied by skull deformation. Many of the skulls with single-suture CS were microcephalic, which may be the cause of the premature synostosis. By contrast, microcephaly may be a resulting phenomenon in multi-suture CS. We noticed that the quotient between height of the cranial vault (vertex-porion distance) and head circumference, multiplied by 100, was 26 or higher only in those CS cases with multi-suture involvement. We therefore consider this parameter, which we named "acrocephalic index", to be an indicator of multi-suture involvement in individual CS cases. In two adult skulls, the skull had a quadrangular shape, which we assumed to be correlated to the presence of an unusually interdigitated open metopic suture. We propose to name this anomaly: tetragonocephaly. Another presumed suture-related condition, bathrocephaly, was found concomitantly with basilar invagination in several cases. We hypothesize that the chronically raised intracranial pressure in these cases caused the still open lambdoidal sutures to distend and the occipital bone to protrude.

Deformation of the mandible due to neonatal moulding: a 10-year follow-up

A 3-day-old infant with paralysis of the marginal mandibular branch of the facial nerve and asymmetry of the mandible due to neonatal moulding is presented. Ten years after the initial presentation, the asymmetry and paralysis was still present. Orthodontic treatment has been instituted because of malocclusion. Surgical correction of the mandibular asymmetry after adulthood seems not to be necessary.

Quantitative transcriptional analysis of fusing and nonfusing cranial suture complexes in mice

Previous studies have documented the differences in expression of various genes associated with the process of osteogenesis in fusing and nonfusing cranial sutures, including growth factors, growth factor receptors, and extracellular matrix molecules. Most of these studies were performed in rats, and although the biology regulating cranial suture fusion in mice and rats is presumed to be similar, studies are needed to verify these expression patterns as mice become increasingly utilized for scientific inquiry into the molecular biology of suture fusion and patency. The purpose of this study was to determine the differences in expression of several genes known to be critical to osteoblast biology. Posterior frontal and sagittal suture complexes (including the associated dura mater, suture mesenchyme, and osteogenic fronts) were isolated from 5-, 15-, 25-, 35-, and 45-day-old male CD-1 mice (n = 8 per age; n = 40 total). Total cellular RNA was extracted and converted to cDNA. Quantitative real-time reverse transcriptase polymerase chain reaction was then performed for the following genes: transforming growth factor beta1 and beta3, fibroblast growth factor receptor 1, Runx2,Osteopontin, and Osteocalcin. Expression of all genes examined was increased significantly in the posterior frontal suture as compared with the sagittal suture. Peak expression for all genes was observed on day 25. These data demonstrate that the expression of osteogenic growth factors, growth factor receptors, transcription factors, and extracellular matrix molecules is increased in the fusing posterior frontal suture in mice.

Intermittent Hydrostatic Compression Promotes Nitric Oxide Production and Osteodifferentiation of Fetal Dural Cells

PURPOSE

The aim of these studies was to evaluate the biologic response of fetal dural cell cultures to compressive mechanical force.

METHODS

Primary cell cultures from the dura mater of E18 CD-1 mice were subjected to 2 PSI of intermittent hydrostatic compression (IHC) at a frequency of 0.5 Hz. Quantitative measures of the expression of Osterix (Osx), osteopontin (OP), endothelial nitric oxide synthase (eNOS) and Noggin were performed by RT-PCR following 3, 6, and 12 hours of exposure to IHC. Nitric oxide production was quantified through the measurement of NO metabolites following 6 hours of exposure to IHC.

RESULTS

IHC resulted in an increase in Osx, OP, and eNOS expression compared with controls at all time points. The expression of Noggin decreased at all time points. Exposure to IHC resulted in a significant increase in the production of NO metabolites at 6 hours when compared with controls.

CONCLUSIONS

These experiments indicate that dural cell biology is significantly altered following exposure to IHC. Specifically, IHC promotes production of NO and osteodifferentiation in fetal dural cell cultures, with increases in the expression of osteoinductive genes and decreases in inhibitors of osteogenesis.

Transforming growth factor-beta isoform expression in the perisutural tissues of craniosynostotic rabbits

OBJECTIVE

To describe the expression patterns of the various transforming growth factor-beta (Tgf-beta) isoforms, known to be involved in suture development, in the perisutural tissues of rabbits with naturally occurring craniosynostosis and relate such differential expression to the pathogenesis of premature suture fusion.

METHOD

Twenty-one coronal sutures were harvested from six wild-type control New Zealand White rabbits and five rabbits with familial coronal suture synostosis at 25 days of age for histomorphometric and immunohistochemical analyses. Tgf-beta isoform immunoreactivity was assessed using indirect immunoperoxidase procedures with specific antibodies.

RESULTS

Synostosed sutures had significantly (p <.01) greater bone area and relatively more osteoblasts and osteocytes in the osteogenic fronts, compared with wild-type sutures. Tgf-beta isoform immunoreactivity showed differential staining patterns between wild-type and synostosed perisutural tissues. In wild-type sutures, Tgf-beta1 and Tgf-beta3 immunoreactivity was significantly (p <.001) greater than Tgf-beta2 staining in all perisutural tissues. In synostosed sutures, the opposite pattern was observed, with Tgf-beta2 immunoreactivity significantly (p <.001) greater than Tgf-beta1 and Tgf-beta3 in the osteogenic fronts, dura mater, and periosteum.

CONCLUSIONS

Findings from this study suggest that an overexpression of Tgf-beta2, either in isolation or in association with an underexpression of Tgf-beta1 and Tgf-beta3, may be related to premature suture fusion (craniosynostosis) in this pathological rabbit model. These abnormal expression patterns may be involved in premature suture fusion either through increased cell proliferation, decreased apoptosis of the osteoblasts or both at the osteogenic fronts.

Update on craniofacial surgery

Over the course of the past year, many interesting aspects of the multidisciplinary approach to the treatment of craniofacial disorders have been furthered. Several authors have shared their experiences, and new innovations have been described. Traditional ideas with regard to bone healing and growth have been expanded upon, and the role of alloplasts also is better understood now. Diagnosis and treatment planning have come a long way with the advent of new imaging techniques and applications. The ongoing discussion regarding absorbable fixation devices has continued, and the development of new technology has been presented. Some new techniques have also been brought to the forefront. Of note, distraction osteogenesis has been embraced as a viable alternative to traditional maxillomandibular surgery with bone grafting as well as other morbid procedures.