Phenotypic integration of neurocranium and brain

Evolutionary history of Mammalia provides strong evidence that the morphology of skull and brain change jointly in evolution. Formation and development of brain and skull co-occur and are dependent upon a series of morphogenetic and patterning processes driven by genes and their regulatory programs. Our current concept of skull and brain as separate tissues results in distinct analyses of these tissues by most researchers. In this study, we use 3D computed tomography and magnetic resonance images of pediatric individuals diagnosed with premature closure of cranial sutures (craniosynostosis) to investigate phenotypic relationships between the brain and skull. It has been demonstrated previously that the skull and brain acquire characteristic dysmorphologies in isolated craniosynostosis, but relatively little is known of the developmental interactions that produce these anomalies. Our comparative analysis of phenotypic integration of brain and skull in premature closure of the sagittal and the right coronal sutures demonstrates that brain and skull are strongly integrated and that the significant differences in patterns of association do not occur local to the prematurely closed suture. We posit that the current focus on the suture as the basis for this condition may identify a proximate, but not the ultimate cause for these conditions. Given that premature suture closure reduces the number of cranial bones, and that a persistent loss of skull bones is demonstrated over the approximately 150 million years of synapsid evolution, craniosynostosis may serve as an informative model for evolution of the mammalian skull.

Long-term aesthetic results of frontoorbital correction for frontal plagiocephaly

OBJECT

Long-term aesthetic results of craniofacial surgery for frontal plagiocephaly were evaluated by two observers who used a scoring system based on deformities typical for this type of craniosynostosis.

METHODS

In this retrospective study, pre- and postoperative photographs of 59 patients were scored for items typical of frontal plagiocephaly: shape of the forehead, orbital dystopia, and temporal depression. Each item was quantified as normal or absent (0 points), a mild deformity (1 point) or a severe deformity (2 points). Preoperatively, the most obvious deformity was the shape of the forehead, whereas postoperatively temporal retrusion was the main deformity. There was a good overall correction of the presenting deformities, with a decline in the mean score from 3.7 to 0.86. There was a statistically significant weak correlation between pre- and postoperative scores for orbital dystopia alone. This finding indicates that the severity of the initial disease is not a major contributor to the final result. Furthermore, the surgical outcome seemed to be stable over time and was not influenced by the timing of surgery if it took place when the children were between 6 and 15 months of age.

CONCLUSIONS

Early craniofacial correction for frontal plagiocephaly results in a stable, acceptable aesthetic outcome on which the initial deformity has little effect. The most common associated craniofacial characteristics are corrected well to very well when surgery is performed within the first 6 to 15 months of life. The main focus of the deformity in both the short and long-term remains the temporal depression, and thus it requires extra attention during surgery.

Linking Antley–Bixler syndrome and congenital adrenal hyperplasia: A novel case of P450 oxidoreductase deficiency

The Antley-Bixler syndrome (ABS) is a multiple congenital malformation syndrome with craniosynostosis, radiohumeral synostosis, femoral bowing, choanal atresia or stenosis, joint contractures, urogenital abnormalities and, often, early death. Autosomal recessive and dominant inheritance have been postulated, as has fluconazole teratogenesis. Mutations in POR (P450 (cytochrome) oxidoreductase, an essential electron donor to enzymes participating in cholesterol biosynthesis), have been identified in some patients with the ABS phenotype. Recent evidence suggests that these mutations cause attenuated steroid hydroxylation, which in turn, causes congenital adrenal hyperplasia (CAH) with ambiguous genitalia in both sexes and glucocorticoid deficiency. Here, we report on a new patient with findings of both ABS and CAH that further illustrates how low maternal estriol at prenatal screening can serve as a marker steroid facilitating early diagnosis.

A newly recognized, likely autosomal recessive syndrome comprising agammaglobulinemia, microcephaly, craniosynostosis, severe dermatitis, and other features

We present a novel, likely autosomal recessive, multi-system disorder seen in three siblings, two males and one female, born to nonconsanguineous parents. The disease manifests as agammaglobulinemia with marked microcephaly, significant developmental delay, craniosynostosis, a severe dermatitis, cleft palate, narrowing of the choanae, and blepharophimosis. The constellation of clinical signs seen in this family likely represents a new and recognizable form of agammaglobulinemia due to a defect in early B-cell maturation.

Genotype-epigenotype-phenotype correlations in females with frontometaphyseal dysplasia

Frontometaphyseal dysplasia (FMD) belongs to a group of overlapping skeletal dysplasias, the common molecular basis of which are mutations of FLNA, the gene encoding filamin A. The nature of the mutation has been considered the major determinant of the phenotype within this group that comprises the otopalatodigital syndromes (OPD1, OPD2) and Melnick-Needles syndrome besides FMD. However, to date the molecular pathomechanisms are not well understood. In FMD only few FLNA mutations have been reported which do not cluster in a specific region of the protein. We report on a novel de novo mutation 5182G --> T in exon 31 of the FLNA gene in a girl with manifestations of FMD and OPD1. This mutation is predicted to lead to the exchange of a highly conserved glycine residue at position 1,728 by cysteine (G1728C) in repeat 15 of the filamin A rod domain. In a second family with FMD, we identified a known mutation (S1186L) in a mother and her son. In contrast to most previous reports on manifesting females or carriers of the FLNA-related skeletal dysplasias, the affected females presented here showed only mild to moderate skewing of X-inactivation against the mutant allele. Our data may indicate that in females, genotype-phenotype correlation between certain FLNA mutations and OPD1 and FMD, respectively, is less strict than previously assumed. We propose that X-inactivation is an important epigenetic modifier of the phenotype in females with the FLNA-related skeletal dysplasias.

FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited

The recent identification of TGFBR2 mutations in Marfan syndrome II (MFSII) [Mizuguchi et al. (2004); Nat Genet 36:855-860] and of TGFBR1 and TGFBR2 mutations in Loeys-Dietz aortic aneurysm syndrome (LDS) [Loeys et al. (2005); Nat Genet 37:275-281] [OMIM 609192] has provided direct evidence of abnormal signaling in transforming growth factors beta (TGF-beta) in the pathogenesis of Marfan syndrome (MFS). In light of this, we describe the phenotypes and genotypes of five individuals. Patient 1 had MFS and abnormal cranial dura. Patient 2 had severe early onset MFS and an abnormal skull. Patients 3 and 4 had probable Furlong syndrome (FS). Patient 5 had marfanoid (MD) features, mental retardation (MR), and a deletion of chromosome 15q21.1q21.3. All patients had a condition within the MFS, MD-craniosynostosis (CS) or MD-MR spectrum. The names of these entities may become redundant, and instead, come to be considered within the spectrum of TGF-beta signaling pathway disorders. Two recurrent heterozygous FBN1 mutations were found in Patients 1 and 2, and an identical novel heterozygous de novo TGFBR1 mutation was found in Patients 3 and 4, in whom altered fibrillin-1 processing was demonstrated previously [Milewicz et al. (2000); Am J Hum Genet 67:279]. A heterozygous FBN1 deletion was found in Patient 5. These findings support the notion that perturbation of extracellular matrix homeostasis and/or remodeling caused by abnormal TGF-beta signaling is the core pathogenetic mechanism in MFS and related entities including the MD-CS syndromes.

Ultrasound in the Diagnosis of Craniosynostosis

Diagnosis of craniosynostosis is based on clinical aspects but may be difficult in some cases where characteristic features are missing and radiographic imaging is necessary. In this context near-field high-frequency ultrasound has been used to evaluate the sonographic characteristics of synostotic sutures and its potential confirming the correct diagnosis. Sutures of 26 infants, aged 2-7 months, were investigated by ultrasound (Siemens Elegra, 7.5 MHz linear scanner). Sonographic features of synostotic sutures were correlated to CT imaging and compared to the sonographic and histopathological findings of normal cranial sutures. Hyperechogenic bridging of sutures with or without ridging were the characteristic aspects of synostotic sutures. All 26 patients could be reliable diagnosed showing partial (n = 21) or total fusion (n = 5) of one or more sutures consisting with craniosynostosis. Length of synostosis was identified exactly by sonography and imaging found to enable a classification of ultrastructural details of bony and soft tissue next to the synostotic suture. Ultrasound is a less expensive, nonradiating and easy-to-handle tool ensuring the diagnosis of craniosynostosis. Sonography offers the potential to be a standard investigation for infants with head deformities suspecting a suture pathology and has been therefore integrated in our craniofacial outpatient clinic as a daily routine method.

Quantifying Positional Plagiocephaly

The treatment of positional plagiocephaly is controversial. A confounding factor is the lack of a proven clinically viable measure to quantify severity and change in plagiocephaly. The use of anthropometric measurements is one proposed method. In this study, the reliability and validity for this method of measurement were investigated. Two clinicians independently recorded caliper measurements of cranial vault asymmetry (CVA) for infants referred for plagiocephaly or torticollis, and an unbiased observer recorded visual analysis scores during the same visit. CVA scores were assigned into three predetermined severity categories (normal CVA < 3 mm, mild/moderate CVA <or= 12 mm, moderate/severe CVA > 12 mm). CVA measurements and visual analysis scores were recorded for 71 and 54 infants, respectively. Intrarater reliability was established (kappa = 0.98, kappa = 0.99), but inter-rater reliability was not (kappa = 0.42). In addition, the inter-rater reliability for the severity categories based upon these measures was poor (kappa = 0.28) and failed to correlate to the visual analysis (kappa = 0.31). Development of a stable and meaningful measurement system for the extent of plagiocephaly is needed to allow scientific studies of the natural history of plagiocephaly and effectiveness of interventions.

Diagnosis of isolated sagittal synostosis: are radiographic studies necessary?

AIMS AND OBJECTIVES

Isolated sagittal synostosis can be diagnosed easily on clinical grounds. This study was designed to determine if children could be operated on based solely on a clinical diagnosis or whether such an approach would result in any potentially unnecessary surgeries.

MATERIALS AND METHODS

Records of 114 consecutive children operated on for isolated nonsyndromic sagittal synostosis over a 14-year period (1987-2000) were reviewed to see whether the clinical findings were in concordance with the intraoperative findings and histopathology of the sagittal suture.

RESULTS

The age at surgery ranged from 1.9 to 81.3 months (median 4.3 months). Preoperative skull radiographs were done in 78 children and computer tomography (CT) scans of the head in 12 children. One hundred percent of the skull radiographs and 83.3% of the CT scans were completed prior to referring the children to a pediatric neurosurgeon. CT scans confirmed the diagnosis in all patients in whom it was available. For the rest, pathology reports and/or operative records were available for 108 (94.7%) children and were confirmatory for sagittal craniosynostosis in all.

CONCLUSIONS

Accurate diagnosis of isolated sagittal synostosis can be made clinically, and operative correction can proceed without a need for radiological investigations, unless the clinical features are not completely typical. This approach could result in significantly reduced radiation exposure for the developing brain and could provide economic benefits to health care providers.

Cell mixing at a neural crest-mesoderm boundary and deficient ephrin-Eph signaling in the pathogenesis of craniosynostosis

Boundaries between cellular compartments often serve as signaling interfaces during embryogenesis. The coronal suture is a major growth center of the skull vault and develops at a boundary between cells derived from neural crest and mesodermal origin, forming the frontal and parietal bones, respectively. Premature fusion of these bones, termed coronal synostosis, is a common human developmental anomaly. Known causes of coronal synostosis include haploinsufficiency of TWIST1 and a gain of function mutation in MSX2. In Twist1(+/-) mice with coronal synostosis, we found that the frontal-parietal boundary is defective. Specifically, neural crest cells invade the undifferentiated mesoderm of the Twist1(+/-) mutant coronal suture. This boundary defect is accompanied by an expansion in Msx2 expression and reduction in ephrin-A4 distribution. Reduced dosage of Msx2 in the Twist1 mutant background restores the expression of ephrin-A4, rescues the suture boundary and inhibits craniosynostosis. Underlining the importance of ephrin-A4, we identified heterozygous mutations in the human orthologue, EFNA4, in three of 81 patients with non-syndromic coronal synostosis. This provides genetic evidence that Twist1, Msx2 and Efna4 function together in boundary formation and the pathogenesis of coronal synostosis.

Noggin Underexpression and Runx-2 Overexpression in a Craniosynostosis Rabbit Model

INTRODUCTION

Normal suture fusion has been shown to be driven by the molecular signals elucidated by the underlying dura. However, the pathogenesis of suture fusion in craniosynostosis is not well described. The purpose of our study was to examine the expression patterns of 2 important molecular signals (Noggin and Runx-2) in a cohort of congenital craniosynostotic rabbits to gain a better understanding of suture behavior in craniosynostosis.

METHODS

Coronal (fusing) and sagittal (patent) rabbit cranial sutures from a colony of congenitally synostosed rabbits and wild-type (control) rabbits were harvested at a neonatal time point. These sections were then grown in organ culture and harvested for histology at 0, 7, or 14 days of culture. Fusion percentage was then assessed and an overall fusion score was calculated. Expression of Noggin and Runx-2 was then localized by immunohistochemistry and quantified by Western blot analysis.

RESULTS

Histology of the wild-type cranial sutures (control) showed suture patency (score of 0%) for all coronal and sagittal sutures at 0 days, 7 days, and 14 days of organ culture. Sagittal sutures of craniosynostotic animals also showed suture patency (score of 0%) at all culture times (0, 7, and 14 days). Of the 18 coronal sutures from the craniosynostotic animals, 8 remained patent and 10 fused. For the coronal sutures that fused, fusion scores of 14%, 41%, and 84% were documented at 0, 7, and 14 days of organ culture, respectively. With immunolocalization, Noggin was found to be expressed in both the dura and suture cells underlying patent sutures, but not in fusing sutures in vitro. Runx-2 was found to be expressed in the dura beneath the suture and suture cells of fusing sutures, not patent sutures. Western blot densitometry confirmed these findings.

CONCLUSIONS

Our results suggest that pathologic rabbit coronal sutures progressed toward complete suture fusion in vitro, and expression patterns of Noggin and Runx-2 paralleled that of a well-studied normal suture fusion model.

Early surgical treatment of nonsyndromic craniosynostosis

BACKGROUND

Craniosynostosis, a premature fusion of cranial sutures, can happen as an isolated defect (nonsyndromic) or as part of a syndrome. It may lead to raised intracranial pressure and deformity of both the cranial and facial skeletons. Early surgery is usually the best treatment choice. The aim of this study was to review the experience of a multidisciplinary staff with the surgical treatment of nonsyndromic craniosynostosis.

METHODS

All the nonsyndromic craniosynostosis cases treated surgically from 1991 to 2005 at 2 neurosurgical centers were reviewed. The variables analyzed were sex, age, weight, type of deformity, estimated volemia, surgical technique, surgical time, blood loss, PO hospitalization time, and complications. All data were stored in a database and analyzed with Microsoft Access (Microsoft Corp, Seattle, WA) and SPSS V11.0 (SPSS, Inc, Chicago, IL).

RESULTS

The sample consisted of 120 patients (70 males, 50 females). Six patients were excluded because of their atypical timing of treatment (average age, 72 months). The final average age was 7.08 months (variation, 1-18), and the average weight was 7.8 kg. The types of deformities found were scaphocephaly (n = 54, 45%), plagiocephaly (n = 27, 22%), trigonocephaly (n = 19, 16%), brachycephaly (n = 16, 13%), and oxycephaly (n = 4, 3%). The mean surgical time was 186 minutes and the mean PO hospitalization time was 6.8 days. The mortality on this series was 2.6% (3 patients). In the last operated cases, a significant improvement in morbid-mortality was observed.

CONCLUSION

A multidisciplinary approach, including neurosurgeons, neurologists, and pediatricians, and appropriate training of the clinical surgical staff can minimize the risks and decrease the complications in the treatment of craniosynostosis, leading to a satisfactory outcome.

Fetal exposure to sodium valproate associated with Baller-Gerold syndrome: case report and review of the literature

CASE REPORT

We report three patients with a history of maternal valproate use during pregnancy who presented with a combination of metopic suture synostosis and upper limb malformations, which could be diagnosed as Baller-Gerold syndrome (BGS). The patients underwent surgical treatment for the craniofacial deformity, during which standard frontocranial reconstruction was performed.

REVIEW OF THE LITERATURE

Only 32 patients have been reported in the world literature and these cases support the emerging view that BGS is not a distinct syndrome, but should instead be considered to be an heterogeneous phenotype with variable etiology.

CONCLUSIONS

Our case series suggests for the first time that fetal sodium valproate exposure may also cause this phenotype.

Mild craniosynostosis with 1p36.3 trisomy and 1p36.3 deletion syndrome caused by familial translocation t(Y;1)

We report on a 20-year-old man and a 16-year-old woman with a chromosomal imbalance derived from a balanced translocation, t(Y;1)(q12;p36.3) of the father. The man had a partial trisomy for 1p36.3-pter [46,X,der(Y)t(Y:1)(q12;p36.3)] and mild craniosynostosis of metopic and sagittal sutures as well as a borderline mental impairment, while the woman with a deletion for 1p36.3-pter [46,XX,der(1)t(Y;1)(q12;p36.3)] showed dysmorphic face with large anterior fontanel and severe developmental delay. Fluorescence in situ hybridization (FISH) showed that his trisomy spanned the 5.3-Mb region from 1p telomere harboring the critical region for craniosynostosis. To our knowledge, the man is the first case of a pure type of simple 1p36.3 trisomy as the effect of heterochromatic Yq12-qter deletion likely does not affect phenotype.

Nanostructural and Nanomechanical Properties of Synostosed Postnatal Human Cranial Sutures

Craniosynostosis represents a heterogeneous cluster of congenital disorders and manifests as premature ossification of one or more cranial sutures. Cranial sutures serve to enable calvarial growth and function as joints between skull bones. The mechanical properties of synostosed cranial sutures are of vital importance to their function and yet are poorly understood. The present study was designed to characterize the nanostructural and nanomechanical properties of synostosed postnatal sagittal and metopic sutures. Synostosed postnatal sagittal sutures (n = 5) and metopic sutures (n = 5) were obtained from craniosynostosis patients (aged 9.1 +/- 2.8 months). The synostosed sutural samples were prepared for imaging and indentation on both the endocranial and ectocranial surfaces with the cantilever probe of an atomic force microscopy. Analysis of the nanotopographic images indicated robust variations in sutural surface characteristics with localized peaks and valleys. In 5 x 5 mum scan sizes, the surface roughness of the synostosed metopic suture was significantly greater (223.6 +/- 93.3 nm) than the synostosed sagittal suture (142.9 +/- 80.3 nm) (P < 0.01). The Young's modulus of the synostosed sagittal suture at 0.7 +/- 0.2 MPa was significantly higher than the synostosed metopic suture at 0.5 +/- 0.1 MPa (P < 0.01). These data suggest that various synostosed cranial sutures may have different structural and mechanical characteristics.

Elejalde syndrome—A case report

Elejalde syndrome (McKusick 200995), also known as acrocephalopolydactylous dysplasia, is a rare condition. We describe a sixth patient with this syndrome which is characterized by craniosynostosis and hyperproliferation of fibroblasts in many tissues including skin, liver, kidney, and pancreas. The cause of the syndrome is the homozygous state of an autosomal recessive mutation. We present a hypothesis that Elejalde syndrome might be associated with an inactivating FGFR gene mutation.

Clinical dividends from the molecular genetic diagnosis of craniosynostosis

A dozen years have passed since the first genetic lesion was identified in a family with craniosynostosis, the premature fusion of the cranial sutures. Subsequently, mutations in the FGFR2, FGFR3, TWIST1, and EFNB1 genes have been shown to account for approximately 25% of craniosynostosis, whilst several additional genes make minor contributions. Using specific examples, we show how these discoveries have enabled refinement of information on diagnosis, recurrence risk, prognosis for mental development, and surgical planning. However, phenotypic variability can present a significant challenge to the clinical interpretation of molecular genetic tests. In particular, the difficulty of analyzing the complex interaction of genetic background and prenatal environment in determining clinical features, limits the value of identifying low penetrance mutations.

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.

Nonsynostotic Occipital Plagiocephaly: Radiographic Diagnosis of the ???Sticky Suture???

BACKGROUND

While the clinical differences between nonsynostotic occipital plagiocephaly and lambdoid craniosynostosis have been described, the radiographic differentiation between the two remains obscure. The aim of this study was to characterize morphological differences in the lambdoid suture between nonsynostotic occipital plagiocephaly and lambdoid craniosynostosis.

METHODS

Computed tomography scans of children clinically diagnosed with nonsynostotic occipital plagiocephaly (n = 26) were compared with computed tomography scans from children diagnosed with lambdoid craniosynostosis (n = 7). Suture and cranial morphology, ear position, and endocranial base angles were qualitatively and quantitatively compared.

RESULTS

Nonsynostotic occipital plagiocephaly sutures demonstrated areas of focal fusion (25 percent), endocranial ridging (78 percent), narrowing (59 percent), sclerosis (19 percent), and changes from overlapping to end-to-end orientation (100 percent). No sutures demonstrated ectocranial ridging. All cases of nonsynostotic occipital plagiocephaly presented with ipsilateral occipital flattening, 85 percent with ipsilateral frontal, and 95 percent with contralateral occipital bossing producing parallelogram morphology. In contrast, a greater frequency of sutures in lambdoid craniosynostosis patients demonstrated nearly complete obliteration (p < 0.001) with ectocranial ridging (p < 0.001); significantly more of these patients presented with ipsilateral occipital flattening with compensatory ipsilateral mastoid (p < 0.001) and contralateral parietal (p < 0.01) bossing, producing a trapezoid morphology. Sutures from nonsynostotic occipital plagiocephaly patients showed endocranial ridging, focal fusions, and narrowing, previously reported as lambdoid craniosynostosis.

CONCLUSIONS

In contradiction to previous reports, lambdoid craniosynostosis is not radiographically unique among suture fusions. This work establishes the radiographic diagnosis of nonsynostotic occipital plagiocephaly.

Endoscopic-assisted repair of craniosynostosis

Object

The goal of the craniofacial surgeon has always been the correction of form and function with prevention of associated morbidity and death. Through the pioneering work of Jimenez and Barone, minimally invasive approaches to the surgical correction of craniosynostosis are now gaining wider acceptance. Here the authors review the technique for endoscopic-assisted repair of craniosynostosis from the perspective of a new minimally invasive approach. They also assess the safety, efficacy, and results of the early treatment of infants with craniosynostosis in a small series of children who underwent surgery at this institution.

Methods

Data regarding synostosis type, operative time, patient age, blood loss, transfusion rates, duration of hospitalization, and complications were collected. Nineteen patients (12 girls and seven boys) between the ages of 1.2 and 5 months of age were treated with the endoscope-assisted technique. The mean operative time was 97 minutes. Five (26%) of 19 children received a blood transfusion. Most patients were discharged home the morning after surgery. The clinical courses of two patients who required additional major craniofacial reconstructions are discussed. There were no deaths, dural sinus tears, cerebrospinal fluid leaks, neurological injuries, or infections, and there were no complications related to the use of helmet therapy. Seventeen of the 19 patients achieved excellent cosmetic results with a single surgery.

Conclusions

This small series supports larger experiences and indicates that early treatment of craniosynostosis with minimally invasive, endoscope-assisted techniques is safe; limits blood transfusion, hospital stay, and operative time; and represents a valuable alternative to the traditional calvarial reconstruction methods.