The timing of physiologic closure of the metopic suture: a review of 159 patients using reconstructed 3D CT scans of the craniofacial region

Evaluating Children With Metopic Craniosynostosis: The Cephalic Width-Intercoronal Distance Ratio

OBJECTIVE

To identify an additional objective measure to aid in the evaluation of children with isolated metopic craniosynostosis.

DESIGN

This is a retrospective study comparing specific computed tomography scan measurements between surgical and nonsurgical cohorts of children with isolated metopic craniosynostosis. Children were included if they were diagnosed with isolated metopic craniosynostosis and ultimately underwent computed tomography scan imaging as part of their evaluation. The subjects were placed in the surgical or nonsurgical cohorts on the basis of the final treatment recommendation after they completed a full multidisciplinary, multimodality evaluation. Comparisons were made with a control group of unaffected patients from our institutional trauma registry.

SETTING

Tertiary academic institution.

PATIENTS, PARTICIPANTS

The subjects are patients who had been previously evaluated in our clinic for isolated metopic craniosynostosis and received a computed tomography scan as part of their workup.

RESULTS

The average intercoronal distances were significantly different among all three groups (P < .002). The average cephalic width-intercoronal distance ratio for children who received a recommendation for surgery differed significantly from that of both the observation cohort and the control group (P < .001). However, the cephalic width-intercoronal distance ratio did not differ between the observation cohort and the control group (P = .927).

CONCLUSIONS

The cephalic width-intercoronal distance ratio may be an additional objective measurement to aid in the clinical evaluation of children with metopic craniosynostosis.

Prenatal Diagnosis of Nasal Glioma Associated with Metopic Craniosynostosis: Case Report and Review of the Literature

Nasal gliomas (nasal glial heterotopia) are rare benign congenital frontonasal lesions occurring in approximately 1:20.000-40,000 live births. The diagnosis is rarely reported prenatally. Nasal gliomas are typically isolated lesions, with syndromic association being exceedingly rare. Metopic craniosynostosis can occur as an isolated abnormality or in association with multiple syndromes. This case is the first reported case of nasal glioma in association with craniosynostosis in the published literature.

A functional aesthetic approach to correcting the sequelae of sagittal synostosis

Sagittal synostosis is the most commonly treated form of craniosynostosis exhibiting an incidence of 1:5000 births.(1) Early closure of the sagittal suture is the cause of the classic phenotypic presentation of an elongated head, which is characterized by a narrow and low occiput, a saddle-shaped parietal region, and noticeable frontal bossing. Early surgical intervention is the treatment of choice and surgical options range from simple suture excision to total cranial vault remodeling. Noting that a significant proportion of patients present with limited frontal bossing and asymmetry that is more pronounced in the posterior cranium, the author developed the functional aesthetic approach to reconstruction. This operative technique addresses the changes noted in the posterior two-thirds of the cranial vault, completely correcting the sequelae associated with early closure of the sagittal suture. As an added advantage, the reconstructive paradigm is designed to create a dynamic temporal-occipital component that will activate when a child rests in the supine position. This enhances widening of the posterior cranium thus improving long-term results.

Correction of metopic synostosis utilizing an in situ bandeau approach

Metopic craniosynostosis is a common growth disturbance in the infant cranium, second only to sagittal synostosis. Presenting symptoms are usually of a clinical nature and are defined by an angular forehead, retruded lateral brow, bitemporal narrowing, and a broad-based occiput. These changes create the pathognomonic trigonocephalic cranial shape. Aesthetic in nature, these morphological changes do not constitute the only developmental issues faced by children who present with this malady. Recent studies and anecdotal evidence have also demonstrated that children who present with metopic synostosis may face issues with respect to intellectual and/or psychological development. The authors present an elegant approach to the surgical reconstruction of the trigonocephalic cranium using an in situ bandeau approach.

Molecular basis of cranial suture biology and disease: Osteoblastic and osteoclastic perspectives

The normal growth and development of the skull is a tightly regulated process that occurs along the osteogenic interfaces of the cranial sutures. Here, the borders of the calvarial bones and neighboring tissues above and below, function as a complex. Through coordinated remodeling efforts of bone deposition and resorption, the cranial sutures maintain a state of patency from infancy through early adulthood as the skull continues to grow and accommodate the developing brain's demands for expansion. However, when this delicate balance is disturbed, a number of pathologic conditions ensue; and if left uncorrected, may result in visual and neurocognitive impairments. A prime example includes craniosynostosis, or premature fusion of one or more cranial and/or facial suture(s). At the present time, the only therapeutic measure for craniosynostosis is surgical correction by cranial vault reconstruction. However, elegant studies performed over the past decade have identified several genes critical for the maintenance of suture patency and induction of suture fusion. Such deeper understandings of the pathogenesis and molecular mechanisms that regulate suture biology may provide necessary insights toward the development of non-surgical therapeutic alternatives for patients with cranial suture defects. In this review, we discuss the intricate cellular and molecular interplay that exists within the suture among its three major components: dura mater, osteoblastic related molecular pathways and osteoclastic related molecular pathways.

New high-resolution computed tomography data of the Taung partial cranium and endocast and their bearing on metopism and hominin brain evolution

Falk and colleagues [Falk D, Zollikofer CP, Morimoto N, Ponce de León MS (2012) Proc Natl Acad Sci U S A 109(22):8467-8470] hypothesized that selective pressures favored late persistence of a metopic suture and open anterior fontanelle early in hominin evolution, and they put an emphasis on the Taung Child (Australopithecus africanus) as evidence for the antiquity of these adaptive features. They suggested three mutually nonexclusive pressures: an "obstetric dilemma," high early postnatal brain growth rates, and neural reorganization in the frontal cortex. To test this hypothesis, we obtained the first high-resolution computed tomography (CT) data from the Taung hominin. These high-resolution image data and an examination of the hominin fossil record do not support the metopic and fontanelle features proposed by Falk and colleagues. Although a possible remnant of the metopic suture is observed in the nasion-glabella region of the Taung partial cranium (but not along the frontal crest), this character state is incongruent with the zipper model of metopic closure described by Falk and colleagues. Nor do chimpanzee and bonobo endocast data support the assertion that delayed metopic closure in Taung is necessary because of widening (reorganization) of the prefrontal or frontal cortex. These results call into question the adaptive value of delaying metopic closure, and particularly its antiquity in hominin evolution. Further data from hominoids and hominins are required to support the proposed adaptive arguments, particularly an obstetric dilemma placing constraints on neural and cranial development in Australopithecus.

An evaluation of complications, revisions, and long-term aesthetic outcomes in nonsyndromic metopic craniosynostosis

BACKGROUND

The authors evaluated the complications, revisions, and long-term aesthetic outcomes of patients with isolated metopic synostosis.

METHODS

A retrospective chart review was performed on consecutive metopic craniosynostosis patients treated from June of 1987 to June of 2012 at The Children's Hospital of Philadelphia. Patient demographics, operative details, and postoperative data were collected. Outcomes were reported as Whitaker classification and postoperative clinical characteristics assessed before additional interventions. Reoperation in patients with greater than 5 years of follow-up was noted. Appropriate statistical analyses were applied.

RESULTS

From 1987 to 2012, 178 patients underwent surgical correction of isolated metopic craniosynostosis, and 147 met inclusion criteria. Average age at surgery was 0.83 year (range, 0.3 to 4.7 years); average follow-up was 5.8 years (range, 1.0 to 17.8 years). There were 13 surgical complications (8.8 percent), three major (2.0 percent), and 10 minor (6.8 percent). At follow-up, 67 patients (56.8 percent) were classified as Whitaker class I, six (5.1 percent) as class II, 43 (36.4 percent) as class III, and two (1.7 percent) as class IV. Patients with greater than 5 years' follow-up (n = 57) were more likely to have temporal hollowing (OR, 2.9; 95 percent CI, 1.2 to 7.3; p = 0.021), lateral orbital retrusion (OR, 4.9; 95 percent CI, 1.9 to 12.7; p = 0.001), and Whitaker class III or IV classification (OR, 4.0; 95 percent CI, 1.5 to 10.6; p = 0.006) compared with those with less than 5 years' follow-up.

CONCLUSION

This study reports low complication and reoperation rates in the treatment of isolated metopic craniosynostosis, but demonstrates a clear trend toward worsening aesthetic outcomes over time.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Evidence-based medicine: Craniosynostosis

LEARNING OBJECTIVES

After studying this article, the participant should be able to: (1) Make the appropriate diagnosis for each of the single-sutural synostoses, based on the physical examination. (2) Explain the functional concerns associated with these synostoses and why surgical correction is indicated. (3) Distinguish between the different types of surgical corrections available, the timing for these various interventions, and in what ways these treatments achieve overall management objectives. (4) Identify the basic goals involved in caring for the syndromic synostoses.

SUMMARY

This article provides an overview of the diagnosis and management of infants with craniosynostosis. This review also incorporates some of the treatment philosophies followed at The Craniofacial Center in Dallas, but is not intended to be an exhaustive treatise on the subject. It is designed to serve as a reference point for further in-depth study by review of the reference articles presented. This information base is then used for self-assessment and benchmarking in parts of the Maintenance of Certification process of the American Board of Plastic Surgery.

Skeletal survey normal variants, artefacts and commonly misinterpreted findings not to be confused with non-accidental injury

Radiology plays a key part in the investigation of non-accidental injury. Many normal variants and artefacts can simulate an abnormality associated with non-accidental injury. It is essential that radiologists reporting skeletal surveys in cases of suspected child abuse are aware of these. We present a pictorial essay to aid the reporting radiologist in the differentiation between normal variants or artefacts and true traumatic injury. We show plain film examples of potential pitfalls throughout the body.

Pathology in metopic synostosis

Premature closure and subsequent ossification of the metopic suture results in triangular head shape called trigonocephaly and is characterized by a midline metopic ridge, frontotemporal narrowing, and an increased biparietal diameter. Trigonocephaly is the second most frequent type of craniosynostosis. It can be isolated and associated with other congenital anomalies without any known syndrome, or occurs as part of a multiple malformation syndrome. Improvement in treatment is directed by a thorough understanding of the basic pathology of this condition. This review aims to provide an overview of metopic synostosis by correlating what is known about pathogenesis and pathology of this entity.

New pathogenesis and the classification in scaphocephaly

The aetiology of scaphocephaly is often described as premature fusion of the sagittal suture. This study observed wave-like deformations in abnormally long and narrow skulls typical of scaphocephaly, and these deformations were divided into two types: type I deformations (one wave) and type II deformations (two waves). However, the pathogeneses of these deformations are unknown. Computed tomographic data sets were retrospectively analyzed from 18 patients with scaphocephaly who were admitted to the hospital between 2000-2010. Using three-dimensional reconstructions of the computed tomographic images, the relationship was analysed between the wave deformation types and the state of the sutures and fontanelles. The results demonstrate that the type of wave deformation was dependent on the location of the sagittal suture closure. Specifically, the premature closure of the posterior half of the sagittal suture caused a type I deformation, while total closure resulted in a type II deformation (p < 0.001). It is hypothesized that restricted growth of the fused suture causes billowing, which results in a waving deformation. The deformities that are often observed in sagittal synostosis can be explained more accurately.

Atypical scaphocephaly: a review

BACKGROUND AND PURPOSE

Sagittal craniosynostosis (SCS) is common and easily recognized and corrected surgically. However, rare cases of SCS are more complex: these associate closure of the metopic or delayed closure of the coronal suture, uni- or bilaterally.

MATERIAL AND METHODS

We reviewed the available literature on atypical sagittal craniosynostosis (ASCS). We also reviewed retrospectively our series of SCS treated since 1980 and selected cases with simultaneous closure of the metopic (leptocephaly) or delayed closure of other sutures (plagiocephaly, oxycephaly, or Crouzon syndrome).

RESULTS

ASCS is rare, representing <10 % of SCS. In our series, among 447 cases of SCS followed for a mean duration of 63.7 months, we identified 22 cases of ASCS: 6 with leptocephaly, 9 with non-syndromic oxycephaly, 4 with Crouzon syndrome, and 3 with plagiocephaly. Fourteen patients required a second operation, either planned initially (severe leptocephaly) or because of brain compression. The actuarial incidence of ASCS requiring reoperation was 5.3 % of SCS at 10 years. After a mean follow-up of 113 months, morphological results in ASCS were grade 1 (no defect) in 5, grade 2 (mild defect) in 2, grade 3 (minor reoperation) in 3, and grade 4 (major reoperation) in 12; one patient had visual impairment, and two had learning difficulties.

CONCLUSIONS

ACSC can be detected initially or occur with a delay in apparently standard SCS. Leptocephaly is a specific entity. Because of the implications on the management and risk for the patient, preoperative evaluation of patients with SCS with CT scanner and prolonged follow-up are necessary.

Metopic suture of Taung (Australopithecus africanus) and its implications for hominin brain evolution

The type specimen for Australopithecus africanus (Taung) includes a natural endocast that reproduces most of the external morphology of the right cerebral hemisphere and a fragment of fossilized face that articulates with the endocast. Despite the fact that Taung died between 3 and 4 y of age, the endocast reproduces a small triangular-shaped remnant of the anterior fontanelle, from which a clear metopic suture (MS) courses rostrally along the midline [Hrdlička A (1925) Am J Phys Anthropol 8:379-392]. Here we describe and interpret this feature of Taung in light of comparative fossil and actualistic data on the timing of MS closure. In great apes, the MS normally fuses shortly after birth, such that unfused MS similar to Taung's are rare. In humans, however, MS fuses well after birth, and partially or unfused MS are frequent. In gracile fossil adult hominins that lived between ∼3.0 and 1.5 million y ago, MS are also relatively frequent, indicating that the modern human-like pattern of late MS fusion may have become adaptive during early hominin evolution. Selective pressures favoring delayed fusion might have resulted from three aspects of perinatal ontogeny: (i) the difficulty of giving birth to large-headed neonates through birth canals that were reconfigured for bipedalism (the "obstetric dilemma"), (ii) high early postnatal brain growth rates, and (iii) reorganization and expansion of the frontal neocortex. Overall, our data indicate that hominin brain evolution occurred within a complex network of fetopelvic constraints, which required modification of frontal neurocranial ossification patterns.

Value of preoperative imaging in the diagnostics of isolated metopic suture synostosis: a risk-benefit analysis

Radiographic evaluation including plain radiographies and computed tomographic (CT) scans are considered as a necessary tool for diagnosis of craniosynostosis. As recently concerns about harmful effects of ionising radiation in children have been raised, some authors have suggested the use of magnetic resonance imaging (MRI) as a helpful alternative in preoperative imaging of patients with isolated metopic synostosis. Besides confirming the diagnosis of trigonocephaly, MRI is the superior technique for the evaluation of underlying brain anomalies. However, if the benefit of preoperative imaging justifies possible side effects is still discussed controversially. Hence, this study investigated the value of preoperative imaging for the diagnosis of isolated synostosis of the metopic suture compared to a sole clinical examination. In a series of 63 cases with isolated metopic craniosynostosis operated at the Department of Oral and Maxillofacial Surgery, 48 (76.2%) patients received additional radiography or MRI investigation, while in 15 (23.8%) patients the diagnosis was based on clinical examinations only. In all patients, diagnosis was confirmed intra-operatively by a fused metopic suture. CT scans with three-dimensional reconstruction (12.5%) or plain radiographs (39.6%) did not provide any additional benefit for the diagnosis or the surgical treatment. In 23 patients (47.9%), MRI showed the typical soft-tissue alterations like triangular brain deformation in the frontal area. Besides these findings, no brain or other underlying anomalies were diagnosed which had required any additional treatment. The incidence of underlying brain abnormalities in isolated metopic synostosis seemed not to be different from that of the general population. As the characteristic clinical manifestations were sufficient for an accurate diagnosis of isolated metopic synostosis, and with respect to the biological effects of ionising radiation and risks of sedation especially in infants, preoperative imaging should be reduced to a minimum.

Metopic synostosis

Premature closure of the metopic suture results in a growth restriction of the frontal bones, which leads to a skull malformation known as trigonocephaly. Over the course of recent decades, its incidence has been rising, currently making it the second most common type of craniosynostosis. Treatment consists of a cranioplasty, usually preformed before the age of 1 year. Metopic synostosis is linked with an increased level of neurodevelopmental delays. Theories on the etiology of these delays range from a reduced volume of the anterior cranial fossa to intrinsic malformations of the brain. This paper aims to provide an overview of this entity by giving an update on the epidemiology, etiology, evolution of treatment, follow-up, and neurodevelopment of metopic synostosis.

Quantitative analysis of developmental process of cranial suture in korean infants

OBJECTIVE

The purpose of this study was to elucidate the anatomical development of physiologic suture closure processes in infants using three dimensional reconstructed computed tomography (CT).

METHODS

A consecutive series of 243 infants under 12 months of age who underwent three dimensional CT were included in this study. Four major cranial sutures (sagittal, coronal, lambdoidal and metopic suture) were classified into four suture closure grades (grade 0=no closure along the whole length, grade 1=partial or intermittent closure, grade 2=complete closure with visible suture line, grade 3=complete fusion (ossification) without visible suture line), and measured for its closure degree (suture closure rates; defined as percentage of the length of closed suture line divided by the total length of suture line).

RESULTS

Suture closure grade under 12 months of age comprised of grade 0 (n=195, 80.2%), grade 1 (n=24, 9.9%) and grade 2 (n=24, 9.9%) in sagittal sutures, whereas in metopic sutures they were grade 0 (n=61, 25.1%), grade 1 (n=167, 68.7%), grade 2 (n=6, 24%) and grade 3 (n=9, 3.7%). Mean suture closure rates under 12 months of age was 58.8% in metopic sutures, followed by coronal (right : 43.8%, left : 41.1%), lambdoidal (right : 27.2%, left : 25.6%) and sagittal sutures (15.6%), respectively.

CONCLUSION

These quantitative descriptions of cranial suture closure may help understand the process involved in the cranial development of Korean infants.

What are the effects of metopic synostosis on visual function?

Metopic synostosis is a premature fusion of the metopic cranial suture. Small case studies into the effects on vision have suggested that there is a raised incidence of astigmatic refractive error with increased risk of failure to develop normal vision if reconstructive surgery is delayed beyond 7 months of age. The aim of this study was to look at a much larger group of patients to give more statistical significance on the incidence of significant refractive error and strabismus in cases of metopic synostosis and compare this with that known for the general population of children at a similar age. A secondary objective was to look at the age at surgery and the visual outcome. A retrospective analysis of case notes was carried out for 64 children with a confirmed diagnosis of metopic synostosis attending the Oxford Craniofacial Unit. Twenty children (31%) were found to have a visual problem, with 18 needing glasses to correct a refractive error and 10 having strabismus. The nature of refractive error was generally hypermetropia, in some cases combined with low astigmatism (1.5 diopters [D] or less). Only 1 child was recorded as having more than 1.5 D of astigmatism. The age at surgery did not seem to influence visual outcome. The incidence of significant refractive error requiring correction and strabismus across the metopic group (31%) was higher than that found in the general population of children at a similar age (5%-11%). This reinforces the importance of orthoptic/ophthalmic surveillance in metopic synostosis.

Preoperative craniofacial dysmorphology in isolated sagittal synostosis: a comprehensive anthropometric evaluation

Although clinical descriptions of altered calvarial shape in isolated sagittal synostosis abound in the literature, systematic quantitative assessment of the total morphologic pattern of preoperative craniofacial dysmorphology remains limited in this population. To address this deficit, a retrospective study was undertaken of 256 preoperative patients younger than 6 years with isolated sagittal synostosis who were seen at the Dallas Craniofacial Center. Patients were examined using a battery of 23 anthropometric measurements of the head and face, from which 10 proportion indices were calculated. The measurements and proportions for each patient were compared with sex- and age-matched norms and converted to standard (Z) scores. The pooled data for each variable were analyzed using 1-sample t-tests. The patients were then separated into 2 age groups--younger than 6 months (n = 162) and 6 months or older (n = 94)--and compared via 2-sample t-tests to examine age-related differences. To further elucidate craniofacial growth patterns, standardized anthropometric measures were then correlated against age. Results indicated that the head was enlarged and elongated with compensatory transverse growth of the anterior cranial vault and reduction in the height of vertex. The face was enlarged, especially along the sagittal axis. The head and face were significantly larger relative to age in children younger than 6 months and show a general decrease in size relative to age in all dimensions except cranial length. The data indicate a complex pattern of dysmorphology, which involves the entire craniofacial complex, not just the cranial vault.

Differential activation of canonical Wnt signaling determines cranial sutures fate: a novel mechanism for sagittal suture craniosynostosis

Premature closure of cranial sutures, which serve as growth centers for the skull vault, result in craniosynostosis. In the mouse posterior frontal (PF) suture closes by endochondral ossification, whereas sagittal (SAG) remain patent life time, although both are neural crest tissue derived. We therefore, investigated why cranial sutures of same tissue origin adopt a different fate. We demonstrated that closure of the PF suture is tightly regulated by canonical Wnt signaling, whereas patency of the SAG suture is achieved by constantly activated canonical Wnt signaling. Importantly, the fate of PF and SAG sutures can be reversed by manipulating Wnt signaling. Continuous activation of canonical Wnt signaling in the PF suture inhibits endochondral ossification and therefore, suture closure, In contrast, inhibition of canonical Wnt signaling in the SAG suture, upon treatment with Wnt antagonists results in endochondral ossification and suture closure. Thus, inhibition of canonical Wnt signaling in the SAG suture phenocopies craniosynostosis. Moreover, mice haploinsufficient for Twist1, a target gene of canonical Wnt signaling which inhibits chondrogenesis, have sagittal craniosynostosis. We propose that regulation of canonical Wnt signaling is of crucial importance during the physiological patterning of PF and SAG sutures. Importantly, dysregulation of this pathway may lead to craniosynostosis.

The frequency of metopism in Anatolian populations dated from the Neolithic to the first quarter of the 20th century

Metopism, which is defined as a condition in which the two pieces of the frontal bone fail to merge in early childhood, displays varying degrees of incidence. In this study, the variation of the frequency of metopism across historical periods is investigated on the skulls of 487 adults from 12 different Ancient Anatolian populations dated to various periods of history ranging from the Neolithic to the first quarter of the 20th century. In addition, the study also examines the relationship of metopism to sex and cranial form. It is revealed that the frequency of metopism showed a relative increase across time periods in Anatolia after the Neolithic Period, with the exception of the Cevizcioğlu Ciftliği population. However, no significant relationship was found between metopism and cranial form or sex. It is found that the frequency of metopism in Ancient Anatolia had a distribution range of 3.3-14.9%. This distribution shows that the inhabitants of Anatolia have a heterogeneous genetic make-up due to the geographical situation of Anatolia, which has been open to gene flow both in the past and at present.

Evaluation of the infant with an abnormal skull shape

PURPOSE OF REVIEW

Atypical skull shapes occur in as many as 20% of infants. The purpose of this review is to discuss the clinical approach to the evaluation of a child with an abnormal head shape. Readers will learn how to identify the head shapes caused by environmental deformation and craniosynostosis. We also review recent findings with regard to the genetics of single-suture craniosynostosis.

RECENT FINDINGS

Healthcare providers can use key aspects of the examination of a child with a head shape abnormality to differentiate positional deformity from craniosynostosis. Overlap between the genetic causes of isolated single-suture craniosynostosis and syndromic forms is discussed.

SUMMARY

Pediatricians can identify the causes of the majority of head shape abnormalities by combining their understanding of normal calvarial growth with a careful physical examination. Molecular genetics is playing an increasing role in the evaluation of children with single-suture fusion.

Impaired posterior frontal sutural fusion in the biglycan/decorin double deficient mice

Biglycan (Bgn) and decorin (Dcn) are highly expressed in numerous tissues in the craniofacial complex. However, their expression and function in the cranial sutures are unknown. In order to study this, we first examined the expression of biglycan and decorin in the posterior frontal suture (PFS), which predictably fuses between 21 and 45 days post-natal and in the non-fusing sagittal (S) suture from wild-type (Wt) mice. Our data showed that Bgn and Dcn were expressed in both cranial sutures. We then characterized the cranial suture phenotype in Bgn deficient, Dcn deficient, Bgn/Dcn double deficient, and Wt mice. At embryonic day 18.5, alizarin red/alcian blue staining showed that the Bgn/Dcn double deficient mice had hypomineralization of the frontal and parietal craniofacial bones. Histological analysis of adult mice (45-60 days post-natal) showed that the Bgn or Dcn deficient mice had no cranial suture abnormalities and immunohistochemistry staining showed increased production of Dcn in the PFS from Bgn deficient mice. To test possible compensation of Dcn in the Bgn deficient sutures, we examined the Bgn/Dcn double deficient mice and found that they had impaired fusion of the PFS. Semi-quantitative RT-PCR analysis of RNA from 35 day-old mice revealed increased expression of Bmp-4 and Dlx-5 in the PFS compared to their non-fusing S suture in Wt tissues and decreased expression of Dlx-5 in both PF and S sutures in the Bgn/Dcn double deficient mice compared to the Wt mice. Failure of PFS fusion and hypomineralization of the calvaria in the Bgn/Dcn double deficient mice demonstrates that these extracellular matrix proteoglycans could have a role in controlling the formation and growth of the cranial vault.

Dynamic Spring Mediated Cranioplasty in an Experimental Model With Resorbable Foot Plates

Craniofacial surgery continues to be progressive in its approach to maximize function and aesthetic appearance while minimizing risks and complications. Dynamic springs are one way to minimize invasiveness while achieving favorable results. The purpose of this study was to show the safety and efficacy of dynamic springs with resorbable foot plates for treatment of metopic suture abnormalities in a swine model. The study population consisted of twelve 20 kg Chester swine. The swine were divided into two treatment groups: four in the sham surgery group and eight in the stainless steel spring group. Postoperative analysis consisted of evaluation of the skull growth over time and integrity of the foot plates and underlying dura. The swine, killed at 8 weeks, were examined for spring location in the foot plates, ease of removal of the spring, and postmortem histologic analysis of the bone growth. No morbidity or mortality occurred in the immediate perioperative period secondary to the surgery. Postmortem histologic analysis revealed no infections or complications related to the surgery. Statistical analysis using a mixed linear model with an unstructured variance-covariance matrix was fit. In conclusion, this study confirms the efficacy and safety of the spring-mediated cranioplasty at the metopic suture with use of resorbable foot plates in a swine model.

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.

Computed tomography pseudofractures of the mid face and skull base

Thin-section multislice CT delineates numerous normal skull-base and mid-facial bony discontinuities. These represent sutures, fissures and neurovascular foramina or channels, and should be differentiated from fractures. This pictorial review describes and illustrates the characteristic location and multiplanar CT appearances of these structures. Their clinical significance in terms of pathological processes and surgical planning are discussed.

Étude des variations morphologiques des scaphocéphalies. Implication pour leur systématisation

PURPOSE

The scaphocephaly is the most frequent craniosynostosis secondary to a premature synostosis of the sagittal suture. Despite this univocal pathogeny there are a great heterogeneity in the skull deformation and their systematisation stay imprecise. The aim of this study was to analyse the different morphology of the scaphocephaly by 3D CT-scan to clarify the different shapes.

MATERIAL AND METHODS

This retrospective study was done from the morphometric analysis of forty-two 3D CT-scan (10 girls and 32 boys). The scaphocephaly was classified in two groups according to the systematisation of Stricker and Montaut: the sphenocephaly (large forehead) and the leptocephaly (narrow forehead). The variation of the calvaria shape was analysed and different index were calculated.

RESULTS

There were 30 sphenocephaly and 12 leptocephaly. Excepted for the forehead deformation there was a morphometric difference of the occipital pole that was backward rotated in the leptocephaly. In the two groups there were retro-coronal constriction (40.5%) or pre-lambdoid constriction (9.5%) independently of the sagittal synostosis degree.

CONCLUSIONS

The morphometric analysis shows that the deformation of the skull secondary to the premature synostosis of the sagittal suture can be different. The adaptative defect of the metopic suture can be to explain this difference. This deformation can be harmonious, or with a retro-coronal constriction resulting in a bitemporal narrowing, or with a pre-lambdoid constriction resulting in an occipital chignon. These results conduce to qualify the surgical correction to adapt at the different shapes.

Three-dimensional sonographic description of the fetal frontal bones and metopic suture

OBJECTIVE

To describe the morphology of the frontal bones and metopic suture at 9-34 weeks of gestation using three-dimensional (3D) ultrasonography.

METHODS

This was a cross-sectional study of the frontal bones and metopic suture in 16 fetuses at 9-34 weeks of gestation. 3D ultrasonography was used to obtain volumes of the whole fetal skull in the mid-sagittal plane. The volumes were analyzed using the rendering mode and transparent maximum mode in order to achieve a clear view of the frontal bones and the metopic suture.

RESULTS

At 9 weeks, a small ossification center was visible in the middle of each supraorbital part of the frontal bones and by 11 weeks the frontal bones appeared as 'thick eyebrows'. In the second trimester there was progressive radial bone expansion and delineation of the metopic suture and in the third trimester there was closure of the metopic suture, starting from the glabella and moving upwards towards the anterior fontanelle.

CONCLUSIONS

This study provides 3D ultrasound images that illustrate the process of ossification of the frontal bones and the subsequent development of the metopic suture during prenatal life.

Neurodevelopmental implications of "deformational" plagiocephaly

Over the past decade there has been a dramatic increase in referrals to specialty clinics, craniofacial centers, plastic surgeons, and neurosurgeons for assessment and treatment of deformational plagiocephaly (DP). Though considered a medically benign condition, preliminary reports suggest that DP may be associated with developmental problems. However, mechanisms to account for this association have not been hypothesized or empirically tested. Although treatment justifications often center on prevention of atypical appearance, little is known about the cosmetic outcomes of treated and untreated children. In this review we hypothesize different etiological pathways linking DP with neurodevelopment (e.g., environmental positioning limitations with and without underlying CNS pathology). We outline directions for research on incidence and prevalence, developmental outcomes, sex differences, determinants of treatment participation, and craniofacial appearance. Despite the paucity of existing research, preliminary findings suggest that children with this condition should be screened and monitored for developmental delays or deficits, as we await more conclusive information from future studies.

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.

Cranial sutures and craniometric points detected on MRI

The main goal of the study was to determine on MRI the cranial sutures, the craniometric points and craniometric measurements, and to correlate these results with classical anthropometric measurements. For this purpose, we reviewed 150 cerebral MRI examinations considered as normal (Caucasian population aged 20-49 years). For each examination we individualized 11 craniometric landmarks (Glabella, Bregma, Lambda, Opisthocranion, Opisthion, Basion, Inion, Porion, Infra-orbital, Eurion) and three measurements. Measurements were also calculated independently on 498 dry crania (Microscribe 3-DX digitizer). To validate the MRI procedure, we measured four dry crania by MRI and with compass or digital caliper gauges. Cranial sutures always appeared without signal (black), whatever the MRI sequence used, and they are better visualized with a 5 mm slice thickness (compact bone overlapping). Slice dynamic analysis and multiplanar reformatting allowed the detection of all craniometric points, some of these being more difficult to detect than others (Porion, Infra-orbital). The measurements determined by these points were as follows: Vertex-Basion height=135.66+/-6.56 mm; Eurion-Eurion width=141.17+/-5.19 mm; Glabella-Opisthocranion length=181.94+/-6.40 mm. On the midline T1-weighted sagittal image, all median craniometric landmarks can be individualized and the Glabella-Opisthocranion length, Vertex-Basion height and parenchyma indices can be calculated. Craniometric points and measurements between these points can be estimated with a standard cerebral MRI examination, with results that are similar to anthropometric data.

New insights into craniosynostosis

Craniosynostosis is a congenital developmental disorder involving premature fusion of cranial sutures, often associated with multiple neurological manifestations. The perspective of this group of disorders has changed dramatically in the new era of molecular genetics. In the last decade a large literature with new concepts in craniosynostosis has appeared. More than 100 syndromes associated with craniosynostosis have been described, and in about a dozen, the molecular defect has been identified. Pediatric neurologists are less aware than geneticists, neurosurgeons, and craniofacial surgeons of these changes. General concepts about craniosynostosis are here presented with updates of clinical and genetic aspects of well-defined syndromes such as Apert, Crouzon, Pfeiffer, Saethre-Chotzen. Evidence of their relationship with fibroblast growth factor receptors (FGFRs) 1, 2, and 3, and with causative genes such as TWIST has been documented. New and other less common syndromes also are discussed. The differences between positional and synostotic plagiocephaly are important, as well as the cause of nonsyndromic craniosynostosis. The prognosis and neurological outcome of patients, including "benign" forms of craniosynostosis, are other important aspects. Major advances have occurred in understanding pathogenesis, diagnosis, and treatment of craniosynostosis. The role of local dura mater and apoptosis; modalities of imaging such as prenatal ultrasound and three-dimensional and spiral CT have improved the accuracy in diagnosis, and the new approaches in surgical treatment involving efficient and less invasive methods, are evidence of these advances.