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

Comparing effectiveness of conservative policy to craniofacial surgery in children with metopic synostosis: protocol for an observational cohort study on clinical outcomes, psychosocial well-being and costs in a Dutch academic hospital

INTRODUCTION

Traditionally, surgical intervention has been the standard treatment for children with metopic synostosis, assuming that it reduces the risk of raised intracranial pressure, thereby preventing vision and cognitive impairment, and also restores the abnormal head shape. However, recent research suggests a sporadic occurrence of raised intracranial pressure in patients with metopic synostosis. In addition, following surgery, an overall tendency to have worse cognitive and behavioral outcomes and more refractive errors compared to healthy peers is observed. Research on conservative (non-surgical) treatment in metopic synostosis is limited and lacks a comparative design. The purpose of this study is to compare the (cost-)effectiveness of conservative and surgical treatment in patients with metopic synostosis.

METHODS AND ANALYSIS

This is the protocol for an observational cohort study with a duration of 8 years. A total of 450 patients with metopic synostosis will be included. The primary outcome is head growth as a predictor for increased intracranial pressure. Non-inferiority with regard to head growth from 0 to 8 years (yearly difference in SD) is determined using a linear mixed model adjusted for potential confounders. Secondary outcomes include papilledema, orthoptic outcomes; forehead shape; cognitive, behavioural and psychological outcomes; and societal costs. A cost-effectiveness analysis will be performed.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the Medical Research Ethics Committee of the Erasmus MC, University Medical Center Rotterdam (MEC-2022-0142). Written informed consent will be obtained from both parents of each participant. The results will be disseminated by publication in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT06069479.

Content Analysis of the Top 25 Most Cited Articles of the Journal of Craniofacial Surgery With ChatGPT-4o

OBJECTIVE

Since 1990, the Journal of Craniofacial Surgery has been an important resource for clinicians and basic scientists. The journal addresses clinical practice, surgical innovations, and educational issues. This study aims to evaluate the contribution of these articles to clinical practice innovations and surgical procedures by analyzing the content of the 25 most cited articles published in the journal. It also aims to demonstrate the potential of artificial intelligence tools in academic content analysis.

METHODS

All articles published in the Journal of Craniofacial Surgery on June 13, 2024, were searched using the Web of Science Database, and the 25 most cited articles were identified. The full texts of these articles were saved in PDF format and metadata were saved as plain text files. Content analysis of these 25 articles was performed using ChatGPT-4o.

RESULTS

As a result of the analysis, some articles stood out in terms of clinical importance. It also appeared that ChatGPT could be used to compare multiple articles.

CONCLUSION

In this study, the authors analyzed the content of the 25 most cited articles published in the Journal of Craniofacial Surgery using ChatGPT-4o. These articles were evaluated according to the criteria of innovations in clinical practice and compliance with surgical procedures. This study presents interesting findings in terms of the use of artificial intelligence tools in academic content analysis. The authors thought that this study could be a source of inspiration for future studies.

Cranial bone microarchitecture in a mouse model for syndromic craniosynostosis

Crouzon syndrome is a congenital craniofacial disorder caused by mutations in the Fibroblast Growth Factor Receptor 2 (FGFR2). It is characterized by the premature fusion of cranial sutures, leading to a brachycephalic head shape, and midfacial hypoplasia. The aim of this study was to investigate the effect of the FGFR2 mutation on the microarchitecture of cranial bones at different stages of postnatal skull development, using the FGFR2C342Y mouse model. Apart from craniosynostosis, this model shows cranial bone abnormalities. High-resolution synchrotron microtomography images of the frontal and parietal bone were acquired for both FGFR2C342Y/+ (Crouzon, heterozygous mutant) and FGFR2+/+ (control, wild-type) mice at five ages (postnatal days 1, 3, 7, 14 and 21, n = 6 each). Morphometric measurements were determined for cortical bone porosity: osteocyte lacunae and canals. General linear model to assess the effect of age, anatomical location and genotype was carried out for each morphometric measurement. Histological analysis was performed to validate the findings. In both groups (Crouzon and wild-type), statistical difference in bone volume fraction, average canal volume, lacunar number density, lacunar volume density and canal volume density was found at most age points, with the frontal bone generally showing higher porosity and fewer lacunae. Frontal bone showed differences between the Crouzon and wild-type groups in terms of lacunar morphometry (average lacunar volume, lacunar number density and lacunar volume density) with larger, less dense lacunae around the postnatal age of P7-P14. Histological analysis of bone showed marked differences in frontal bone only. These findings provide a better understanding of the pathogenesis of Crouzon syndrome and will contribute to computational models that predict postoperative changes with the aim to improve surgical outcome.

[Development and growth of the forehead]

Craniofacial development involves processes leading to the positioning and early growth of the frontal ossification centers. Growth then occurs, mostly secondary to the activity of the sutures, with major interactions with the functional environment, mostly consisting in the growing brain, based on mechanosensation and mechanotransduction mechanisms. Here, we review these processes and assess their relevance in the understanding of craniofacial malformations.

Geometric Morphometric Study on Distinguishing Metopic Craniosynostosis from Metopic Ridging

Background

Craniosynostosis, a common congenital anomaly, results from premature fusion of the cranial sutures. One of the forms of craniosynostosis is premature fusion of the metopic suture, referred to as trigonocephaly, but the diagnosis of metopic suture synostosis remains controversial. The purpose of this study was to clarify, using geometric morphometric analysis, if a metopic ridge alone observed in cases of mild trigonocephaly represents a pathological phenomenon.

Methods

Three different cranial morphologies were compared among patients up to 2 years old who were categorized into the true group, the mild group, and the normal group, based on the presence or absence of specific symptoms, history of cranioplasty for trigonocephaly, or lack of any abnormality on computed tomography. Using the obtained computed tomography images, 235 anatomical landmarks and semi-landmarks were plotted on the entire cranial surface for analysis of neurocranial morphology, and the cranial shapes represented by landmarks were analyzed using geometric morphometrics. Principal components of shape variations among specimens were then computed, based on the variance-covariance matrix of the Procrustes residuals of all specimens, and statistically analyzed.

Results

The principal component analyses of the variations in endocranial shape, frontal bone shape, and occipital bone shape did not show any significant differences in cranial morphology between mild trigonocephaly and normal skulls; however, true trigonocephaly was found to differ significantly from mild trigonocephaly and normal skulls.

Conclusions

These findings suggest that in assessments of cranial morphology, the presence of a ridge alone cannot be diagnosed as fundamentally pathological, and may represent normal morphology.

A critical eye on metopic craniosynostosis: A retrospective study assessing orbital dysmorphology as a marker of disease

This investigation sought to ascertain whether orbital morphology could predict genuine metopic craniosynostosis (MCS). The study retrospectively analyzed preoperative three-dimensional computed tomography (3D-CT) scans of patients who underwent surgical correction for MCS. MCS severity was evaluated using the interfrontal angle (IFA). Orbital dysmorphology was assessed based on multiple angles, including supraorbital notches and nasion (SNS), infraorbital foramina and nasion (INI), zygomaticofrontal suture-supraorbital notch-dacryon (ZSD), and orbital long axis (OLA). Results were juxtaposed against age/gender-matched controls and individuals with non-synostotic metopic ridge (MR). The study included 177 patients: 68 MCS, 35 MR, and 74 control subjects. All orbital measurements exhibited significant differences across groups. IFA demonstrated a strong association with all orbital measurements, particularly SNS (B = 0.79, p < 0.001). SNS showed the highest area under the curve among orbital measurements (0.89). Using a 95% sensitivity threshold, the optimal diagnostic angle for SNS was 129.23° (specificity 54%, sensitivity 96%). These findings suggest a correlation between orbital dysmorphology and trigonocephaly severity. The observed dysmorphology manifested in a superomedially accentuated rotational pattern. Importantly, SNS angle predicted MCS, with an angle greater than 130° indicating <5% likelihood of MCS diagnosis. The simplicity of measuring SNS angle on any 3D-CT scan highlights its practical use for assisting with MCS diagnosis.

Validating the Supraorbital Notch-Nasion-Supraorbital Notch Angle as a Marker for Metopic Craniosynostosis Severity

OBJECTIVE

Metopic craniosynostosis (MCS) can be difficult to differentiate from metopic ridge (MR) or normal frontal morphology. This study assess whether the supraorbital notch-nasion-supraorbital notch (SNS) angle can help identify MCS.

METHODS

Records of 212 patients with preoperative three-dimensional computed tomography scans were examined. The SNS angles, surgeon craniofacial dysmorphology rankings, and CranioRate metopic severity scores (MSSs) were compared with the Spearman rank correlation coefficient. Receiver operating characteristic (ROC) curves with Youden J-statistic and cross-validation of regression models assessed the ability of these measures to predict surgery.

RESULTS

A total of 212 patients were included, consisting of 78 MCS, 37 MR, and 97 controls. Both the mean SNS angle (MCS: 111.7 ± 10.7 degrees, MR: 126.0 ± 8.2 degrees, controls: 130.7 ± 8.8 degrees P < 0.001) and MSS (MCS: 5.9 ± 2.0, MR: 1.4 ± 1.9, controls: 0.2 ± 1.9, P < 0.001) were different among the cohorts. The mean SNS angle (111.5 ± 10.7 versus 129.1 ± 8.8, P < 0.001) was lower in those who had surgery and CranioRate score (5.9 ± 2.1 versus 0.8 ± 2.2, P < 0.001) was higher in those who underwent surgery. SNS angles were positively correlated with surgeon craniofacial dysmorphology rankings ( r = 0.41, P < 0.05) and CranioRate MSS ( r = 0.54, P < 0.05). The ROC curve requiring high sensitivity revealed an SNS angle of 124.8 degrees predicted surgery with a sensitivity of 88.7% and a specificity of 71.3%. A ROC curve using the CranioRate MCC values ≥3.19 predicted surgery with 88.7% sensitivity and 94.7% specificity.

CONCLUSION

Orbital dysmorphology in patients with MCS is well captured by the supraorbital-nasion angle. Both the SNS angle and CranioRate MSS scores accurately predict surgical intervention.

Metopism in adult South Africans and its relationship to frontal sinus size

This study documents the incidences of complete and partial metopism and their possible relationship to frontal sinus volume (FSV) in a sample of modern adult black South Africans with a view to evaluating the hypothesis that metopism affects frontal sinus hypoplasia. FSV was measured from CT scans and the incidence of metopism was recorded from direct observations of dried cadaveric crania. The sex of each individual was known. Four linear cranial dimensions were used to compute a geometric mean by which to scale FSV. The incidence of partial metopism (38%) is comparable to that reported for other population samples, although there is considerable variation among these global sample frequencies. It is significantly more common in male than female South Africans. FSV in individuals with complete metopism is smaller than average but not inordinately so. On the other hand, FSV is significantly larger in individuals with partial metopism than in those that do not present with this sutural remnant. The data on FSV in individuals with and without partial metopism contradict the hypothesis that there is a relationship between partial metopism and frontal sinus hypoplasia. As such, the metopic remnant evinced by the Late Pleistocene cranium from Hofmeyr, South Africa is unlikely to be related to its very small FSV.

Quantitative anatomy of the primary ossification center of the squamous part of temporal bone in the human fetus

Detailed numerical data about the development of primary ossification centers in human fetuses may influence both better evaluation and early detection of skeletal dysplasias, which are associated with delayed development and mineralization of ossification centers. To the best of our knowledge, this is the first report in the medical literature to morphometrically analyze the primary ossification center of the squamous part of temporal bone in human fetuses based on computed tomography imaging. The present study offers a precise quantitative foundation for ossification of the squamous part of temporal bone that may contribute to enhanced prenatal care and improved outcomes for fetuses with inherited cranial defects and skeletodysplasias. The examinations were carried out on 37 human fetuses of both sexes (16 males and 21 females) aged 18-30 weeks of gestation, which had been preserved in 10% neutral formalin solution. Using CT, digital image analysis software, 3D reconstruction and statistical methods, the size of the primary ossification center of the squamous part of temporal bone was evaluated. With neither sex nor laterality differences, the best-fit growth patterns for the primary ossification center of the squamous part of temporal bone was modelled by the linear function: y = -0.7270 + 0.7682 × age ± 1.256 for its vertical diameter, and the four-degree polynomial functions: y = 5.434 + 0.000019 × (age)4 ± 1.617 for its sagittal diameter, y = -4.086 + 0.00029 × (age)4 ± 2.230 for its projection surface area and y = -25.213 + 0.0004 × (age)4 ± 3.563 for its volume. The CT-based numerical data and growth patterns of the primary ossification center of the squamous part of temporal bone may serve as age-specific normative intervals of relevance for gynecologists, obstetricians, pediatricians and radiologists during screening ultrasound scans of fetuses. Our findings for the growing primary ossification center of the squamous part of temporal bone may be conducive in daily clinical practice, while ultrasonically monitoring normal fetal growth and screening for inherited cranial faults and skeletodysplasias.

Ultra-low-dose computed tomography with deep learning reconstruction for craniosynostosis at radiation doses comparable to skull radiographs: a pilot study

BACKGROUND

Craniofacial computed tomography (CT) is the diagnostic investigation of choice for craniosynostosis, but high radiation dose remains a concern.

OBJECTIVE

To evaluate the image quality and diagnostic performance of an ultra-low-dose craniofacial CT protocol with deep learning reconstruction for diagnosis of craniosynostosis.

MATERIALS AND METHODS

All children who underwent initial craniofacial CT for suspected craniosynostosis between September 2021 and September 2022 were included in the study. The ultra-low-dose craniofacial CT protocol using 70 kVp, model-based iterative reconstruction and deep learning reconstruction techniques was compared with a routine-dose craniofacial CT protocol. Quantitative analysis of the signal-to-noise ratio and noise was performed. The 3-dimensional (D) volume-rendered images were independently evaluated by two radiologists with regard to surface coarseness, step-off artifacts and overall image quality on a 5-point scale. Sutural patency was assessed for each of six sutures. Radiation dose was compared between the two protocols.

RESULTS

Among 29 patients (15 routine-dose CT and 14 ultra-low-dose CT), 23 patients had craniosynostosis. The 3-D volume-rendered images of ultra-low-dose CT without deep learning showed decreased image quality compared to routine-dose CT. The 3-D volume-rendered images of ultra-low-dose CT with deep learning reconstruction showed higher noise level, higher surface coarseness but decreased step-off artifacts, comparable signal-to-noise ratio and overall similar image quality compared to the routine-dose CT images. Diagnostic performance for detecting craniosynostosis at the suture level showed no significant difference between ultra-low-dose CT without deep learning reconstruction, ultra-low-dose CT with deep learning reconstruction and routine-dose CT. The estimated effective radiation dose for the ultra-low-dose CT was 0.05 mSv (range, 0.03-0.06 mSv), a 95% reduction in dose over the routine-dose CT at 1.15 mSv (range, 0.54-1.74 mSv). This radiation dose is comparable to 4-view skull radiography (0.05-0.1 mSv) and lower than previously reported effective dose for craniosynostosis protocols (0.08-3.36 mSv).

CONCLUSION

In this pilot study, an ultra-low-dose CT protocol using radiation doses at a level similar to skull radiographs showed preserved diagnostic performance for craniosynostosis, but decreased image quality compared to the routine-dose CT protocol. However, by combining the ultra-low-dose CT protocol with deep learning reconstruction, image quality was improved to a level comparable to the routine-dose CT protocol, without sacrificing diagnostic performance for craniosynostosis.

FGF signaling in cranial suture development and related diseases

Suture mesenchymal stem cells (SMSCs) are a heterogeneous stem cell population with the ability to self-renew and differentiate into multiple cell lineages. The cranial suture provides a niche for SMSCs to maintain suture patency, allowing for cranial bone repair and regeneration. In addition, the cranial suture functions as an intramembranous bone growth site during craniofacial bone development. Defects in suture development have been implicated in various congenital diseases, such as sutural agenesis and craniosynostosis. However, it remains largely unknown how intricate signaling pathways orchestrate suture and SMSC function in craniofacial bone development, homeostasis, repair and diseases. Studies in patients with syndromic craniosynostosis identified fibroblast growth factor (FGF) signaling as an important signaling pathway that regulates cranial vault development. A series of in vitro and in vivo studies have since revealed the critical roles of FGF signaling in SMSCs, cranial suture and cranial skeleton development, and the pathogenesis of related diseases. Here, we summarize the characteristics of cranial sutures and SMSCs, and the important functions of the FGF signaling pathway in SMSC and cranial suture development as well as diseases caused by suture dysfunction. We also discuss emerging current and future studies of signaling regulation in SMSCs.

"Validation of Artificial Intelligence Severity Assessment in Metopic Craniosynostosis"

OBJECTIVE

Several severity metrics have been developed for metopic craniosynostosis, including a recent machine learning-derived algorithm. This study assessed the diagnostic concordance between machine learning and previously published severity indices.

DESIGN

Preoperative computed tomography (CT) scans of patients who underwent surgical correction of metopic craniosynostosis were quantitatively analyzed for severity. Each scan was manually measured to derive manual severity scores and also received a scaled metopic severity score (MSS) assigned by the machine learning algorithm. Regression analysis was used to correlate manually captured measurements to MSS. ROC analysis was performed for each severity metric and were compared to how accurately they distinguished cases of metopic synostosis from controls.

RESULTS

In total, 194 CT scans were analyzed, 167 with metopic synostosis and 27 controls. The mean scaled MSS for the patients with metopic was 6.18 ± 2.53 compared to 0.60 ± 1.25 for controls. Multivariable regression analyses yielded an R-square of 0.66, with significant manual measurements of endocranial bifrontal angle (EBA) (P = 0.023), posterior angle of the anterior cranial fossa (p < 0.001), temporal depression angle (P = 0.042), age (P < 0.001), biparietal distance (P < 0.001), interdacryon distance (P = 0.033), and orbital width (P < 0.001). ROC analysis demonstrated a high diagnostic value of the MSS (AUC = 0.96, P < 0.001), which was comparable to other validated indices including the adjusted EBA (AUC = 0.98), EBA (AUC = 0.97), and biparietal/bitemporal ratio (AUC = 0.95).

CONCLUSIONS

The machine learning algorithm offers an objective assessment of morphologic severity that provides a reliable composite impression of severity. The generated score is comparable to other severity indices in ability to distinguish cases of metopic synostosis from controls.

Impact of age at endoscopic metopic synostosis repair on anthropometric outcomes

OBJECTIVE

Endoscopic strip craniectomy for metopic craniosynostosis relies on rapid growth and postoperative helmeting for correction. Endoscopic repair is generally performed before patients reach 4 months of age, and outcomes in older patients have yet to be quantified. Here, the authors examined a cohort of patients treated with endoscopic repair before or after 4 months of age to determine aesthetic outcomes of delayed repairs.

METHODS

Data from eligible patients were retrospectively assessed and aggregated in a dedicated metopic synostosis database. Inclusion criteria were radiographically confirmed metopic synostosis and endoscopic treatment. Patients were dichotomized into two groups: those younger than 4 months and those 4 months or older at the time of repair. The frontal width and interfrontal divergence angle (IFDA) were measured on reconstructed CT images. These measurements, alongside operative time, estimated blood loss, and transfusion rates, were compared between groups using the Student t-test or chi-square test.

RESULTS

The study population comprised 28 patients treated before 4 months of age and 8 patients treated at 4-6 months of age. Patient sex and perioperative complications did not differ by age group. Older age at repair was not significantly associated with 1-year postoperative IFDA (140° ± 4.2° vs 142° ± 5.0°, p = 0.28) or frontal width (84 ± 5.2 vs 83 ± 4.4 mm, p = 0.47).

CONCLUSIONS

One-year postoperative IFDA and frontal width do not differ significantly between patients treated before and after 4 months of age. Further study with longer follow-up is necessary to confirm the longevity of these results at skeletal maturity.

Paediatric skull growth models: A systematic review of applications to normal skulls and craniosynostoses

INTRODUCTION

Craniosynostoses affect 1/2000 births and their incidence is currently increasing. Without surgery, craniosynostosis can lead to neurological issues due to restrained brain growth and social stigma due to abnormal head shapes. Understanding growth patterns is essential to develop surgical planning approaches and predict short- and long-term post-operative results. Here we provide a systematic review of normal and pathological cranial vault growth models.

MATERIAL AND METHODS

The systematic review of the literature identified descriptive and comprehensive skull growth models with the following criteria: full text articles dedicated to the skull vault of children under 2 years of age, without focus on molecular and cellular mechanisms. Models were analysed based on initial geometry, numerical method, age determination method and validation process.

RESULTS

A total of 14 articles including 17 models was reviewed. Four descriptive models were assessed, including 3 models using statistical analyses and 1 based on deformational methods. Thirteen comprehensive models were assessed including 7 finite element models and 6 diffusion models. Results from the current literature showed that successful models combined analyses of cranial vault shape and suture bone formation.

DISCUSSION

Growth modelling is central when assessing craniofacial architecture in young patients and will be a key factor in the development of future customized treatment strategies. Recurrent technical difficulties were encountered by most authors when generalizing a specific craniosynostosis model to all types of craniosynostoses, when assessing the role of the brain and when attempting to relate the age with different stages of growth.

Impaired wound healing following cranial vault reconstruction in a patient with an atypical phenotype of Marfan syndrome: A case report

Background:

Marfan syndrome (MFS) is an autosomal dominant disorder of the connective tissues caused by mutations in the FBN1 gene which can result in widespread systemic involvement. Loeys-Dietz syndrome (LDS) is a related autosomal dominant disorder of connective tissue with widespread systemic involvement which has phenotypic overlap with MFS. LDS is caused by heterozygous pathogenic variants in six different genes, the most common of which involve transforming growth factor beta-receptor 1 or 2. While LDS is commonly associated with craniofacial manifestations, MFS is not typically characterized by craniosynostosis.

Case Description:

We present a 7-month-old female patient with MFS and metopic craniosynostosis with an unusual clinical presentation who underwent cranial vault reconstruction with fronto-orbital advancement and anterior cranial vault remodeling. Her course was complicated by impaired wound healing after surgery, requiring return to the operating room.

Conclusion:

Phenotypic overlap between genetic disorders can confound clinical diagnosis as illustrated in this case. Genetic testing can be highly valuable in the diagnosis of clinically variable disorders. Patients with MFS who undergo cranial surgery may be at increased risk for wound healing complications.

Prenatal Ultrasound Parameters of Twins With Sagittal Suture Craniosynostosis Question Mechanical Constraint as the Leading Cause

BACKGROUND

Multiple pregnancy is a known predisposing factor for sagittal suture synostosis, and intrauterine constraint has been suggested as a potential cause. This study evaluates prenatal images of single and multiple pregnancies of children with sagittal suture synostosis to assess the possible pathogenesis.

MATERIALS AND METHODS

Prenatal ultrasound data of scaphocephaly twins treated at Erasmus MC was retrieved retrospectively. The head circumference, cephalic index (CI), and biparietal diameter (BPD) were analyzed. Data were compared with the nonaffected sibling, singletons with scaphocephaly, and to general fetal growth reference values.

RESULTS

Data of 8 twin pregnancies with 10 cases of scaphocephaly was gathered. For the head circumference no difference was found between affected fetuses and reference values throughout pregnancy. For the BPD a reduced growth was found, compared with control values. The growth curve for the CI of the affected twins is lower from the start and declines over time. When comparing affected fetuses to nonaffected fetuses, the same differences for the BPD and CI were found as compared with controls. No differences in growth parameters were found between the nonaffected siblings and reference values, nor between the affected scaphocephaly twins and singletons with scaphocephaly.

CONCLUSIONS

Scaphocephaly in twin pregnancy develops early on in pregnancy, similar to singleton pregnancy, making the theory of constraint as a cause less likely. The development of scaphocephaly in twins is likely to be attributed to the same disturbed developmental processes in suture development as in singletons, and not to mechanical constraint.

Fronto-Orbital Advancement for Metopic and Unilateral Coronal Craniosynostoses

Fronto-orbital advancement remains a powerful technique for the correction of anterior cranial vault differences related to metopic (trigonocephaly) or unilateral coronal (anterior plagiocephaly) craniosynostoses. Traditional fronto-orbital advancement requires access to the forehead and superior 2/3 of the orbit via a coronal incision. The frontal bone and orbital segment (bandeau) are then separated from the skull and reshaped. In patients with metopic craniosynostosis, the bandeau and frontal bone will need to be advanced and widened. In patients with unilateral coronal craniosynostosis, the bandeau will need to be "untwisted" to address the supraorbital retrusion on the affected side, the affected orbit will need to be shortened and widened, and the frontal bone flap will need to be proportionately advanced on the affected side. Overcorrection of the affected dimension should be undertaken to account for growth and relapse.

Management of Unicoronal and Metopic Synostoses: Minimally Invasive Approaches

Early endoscopic-assisted correction of unicoronal and metopic synostosis is an excellent, safe, cost-effective, and highly effective option for affected patients. Although open calvarial remodeling has a place in the armamentarium of the craniofacial team, the skull base changes seen in endoscopic-assisted techniques are unparalleled. The procedures are associated with low morbidity and no mortality. There is minimal blood loss, decreased operating time, significantly reduced blood transfusion rates, decreased hospitalization length, decreased cost, and less pain and swelling. Early diagnosis and referral for surgical evaluation are critical to obtaining these results.

Effects of orofacial applications of low-magnitude, high-frequency mechanical vibration on cranial sutures and calvarial bones: A micro-computed tomography study in rats

INTRODUCTION

The purpose of this study was to assess the effects of orthodontically aimed low-magnitude, high-frequency mechanical vibration (OLMHFMV) on intact calvarial bone, specifically the parietal and temporal, and cranial sutures, including the sagittal and parietotemporal, of rats in differing stages of growth and development.

METHODS

Forty Wistar rats were divided into 4 groups: 2 control groups and 2 OLMHFMV groups. Subsequently, 0.3 cN of force with a frequency of 30 Hz was applied as OLMHFMV on the temporomandibular joint region in the rats in the OLMHFMV-1 group, with the protocol of 20 min/d for 5 d/wk for 1 month, whereas the rats in the OLMHFMV-2 group received mechanical stimuli for 2 months with the same protocol. Morphometric and structural analyses, including suture width, cranial width and height, bone mineral density, bone volume/tissue volume, trabecular number, trabecular separation, and trabecular thickness analyses, were carried out using micro-computed tomography.

RESULTS

The width of the parietotemporal and sagittal sutures and the cranial height and width increased significantly by OLMHFMV (P <0.021). The structural analysis revealed that trabecular number and trabecular separation increased, whereas trabecular thickness decreased in the OLMHFMV groups compared with the control groups (P <0.048). Bone volume/tissue volume remained unchanged despite reducing the bone mineral density of the OLMHFMV groups.

CONCLUSIONS

OLMHFMV had a potential for modulating sutural and cranial growth in adolescent rats. OLMHFMV increased the structural quality of the temporal and parietal bones. These effects may have clinical implications as a treatment option for patients suffering from craniofacial anomalies such as craniosynostosis or a supportive approach for dentofacial orthodontic treatments.

Morphologic Differences in Sagittal Synostosis with Age before Surgery

BACKGROUND

It is important to determine whether sagittal synostosis-associated scaphocephaly is static in the presurgical period, or whether there are morphologic differences with time to include in surgical decision-making. The authors' purpose was to perform cross-sectional analysis of cranial morphology before any surgical intervention in children with sagittal synostosis younger than 9 months compared to matched controls.

METHODS

The authors performed morphometric analysis on computed tomographic scans from 111 untreated isolated sagittal synostosis patients younger than 9 months and 37 age-matched normal controls. The authors divided the patients into three age groups and performed statistical comparison between sagittal synostosis and controls for each group.

RESULTS

Sagittal synostosis cephalic indices were stable and lower in patients than in controls across groups. Total cranial volume was equivalent, but sagittal synostosis patients had a greater posterior volume than controls at all ages and a smaller middle fossa volume at older ages. Pterional width was greater in sagittal synostosis patients than in controls for each age group. Frontal bossing vectors were most severe in the youngest age groups and least in the older group. Occipital protuberance was consistent across the age groups.

CONCLUSIONS

Upper parietal narrowing and occipital protuberance were the consistent deformities across age groups, with the most parietal constriction seen in older patients. Frontal bossing was not consistent and was more severe in the younger patients. The authors did not detect significant pterional constriction, and the appearance of constriction is relative to adjacent morphology and not absolute.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

The clinical manifestations, molecular mechanisms and treatment of craniosynostosis

Craniosynostosis is a major congenital craniofacial disorder characterized by the premature fusion of cranial suture(s). Patients with severe craniosynostosis often have impairments in hearing, vision, intracranial pressure and/or neurocognitive functions. Craniosynostosis can result from mutations, chromosomal abnormalities or adverse environmental effects, and can occur in isolation or in association with numerous syndromes. To date, surgical correction remains the primary treatment for craniosynostosis, but it is associated with complications and with the potential for re-synostosis. There is, therefore, a strong unmet need for new therapies. Here, we provide a comprehensive review of our current understanding of craniosynostosis, including typical craniosynostosis types, their clinical manifestations, cranial suture development, and genetic and environmental causes. Based on studies from animal models, we present a framework for understanding the pathogenesis of craniosynostosis, with an emphasis on the loss of postnatal suture mesenchymal stem cells as an emerging disease-driving mechanism. We evaluate emerging treatment options and highlight the potential of mesenchymal stem cell-based suture regeneration as a therapeutic approach for craniosynostosis.

The 27 Facial Sutures: Timing and Clinical Consequences of Closure

SUMMARY

Facial sutures contribute significantly to postnatal facial development, but their potential role in craniofacial disease is understudied. Since interest in their development and physiology peaked in the mid-twentieth century, facial sutures have not garnered nearly the same clinical research interest as calvarial sutures or cranial base endochondral articulations. In addition to reinforcing the complex structure of the facial skeleton, facial sutures absorb mechanical stress and generally remain patent into and beyond adolescence, as they mediate growth and refine the shape of facial bones. However, premature closure of these sites of postnatal osteogenesis leads to disrupted growth vectors and consequent dysmorphologies. Although abnormality in individual sutures results in isolated facial deformities, we posit that generalized abnormality across multiple sutures may be involved in complex craniofacial conditions such as syndromic craniosynostosis. In this work, the authors comprehensively review 27 key facial sutures, including physiologic maturation and closure, contributions to postnatal facial development, and clinical consequences of premature closure.

The use of a single-piece bone flap for cranial reshaping in anterior craniosynostosis patients: clinical experience and a description of a novel technique

Background

Craniosynostosis is known as premature closure of one or more of the cranial sutures. Anterior craniosynostosis involves anterior plagiocephaly and trigonocephaly. One of the issues in anterior craniosynostosis skull reshaping is maintaining an aesthetically pleasing forehead curve. Therefore, in this article, we demonstrate our novel technique to use a single-piece bone flap for cranial reshaping of the anterior mold in patients diagnosed with anterior craniosynostosis. A retrospective record review of patients who underwent single piece bone flap cranial reshaping for correction of unicoronal synostosis (UCS) and metopic synostosis (MS) at an Academic Institute in Riyadh, Saudi Arabia, between 2018 and 2020, was conducted.

Results

Six non-syndromic consecutive patients were included. Three of the patients had MS. The mean age at surgery was 11.16 months (range, 6–19 months). The average OR time was 315 min (range, 263–368 min). The average intraoperative blood loss was 225 ml (range, 100–400 ml). All patients had achieved acceptable functional and aesthetic results.

Conclusion

Our novel technique is an innovative and efficient reconstructive technique to simultaneously address MS and UCS and minimize intraoperative bleeding and surgery time. However, more studies with more cases are required.

Impact of skull sutures, spongiform bone distribution, and aging skull conductivities on the EEG forward and inverse problems

Source imaging is a principal objective for electroencephalography (EEG), the solutions of which require forward problem (FP) computations characterising the electric potential distribution on the scalp due to known sources. Additionally, the EEG-FP is dependent upon realistic, anatomically correct volume conductors and accurate tissue conductivities, where the skull is particularly important. Skull conductivity, however, deviates according to bone composition and the presence of adult sutures. The presented study therefore analyses the effect the presence of adult sutures and differing bone composition have on the EEG-FP and inverse problem (IP) solutions. Utilising a well-established head atlas, detailed head models were generated including compact and spongiform bone and adult sutures. The true skull conductivity was considered as inhomogeneous according to spongiform bone proportion and sutures. The EEG-FP and EEG-IP were solved and compared to results employing homogeneous skull models, with varying conductivities and omitting sutures, as well as using a hypothesised aging skull conductivity model. Significant localised FP errors, with relative error up to 85%, were revealed, particularly evident along suture lines and directly related to the proportion of spongiform bone. This remained evident at various ages. Similar EEG-IP inaccuracies were found, with the largest (maximum 4.14 cm) across suture lines. It is concluded that modelling the skull as an inhomogeneous layer that varies according to spongiform bone proportion and includes differing suture conductivity is imperative for accurate EEG-FP and source localisation calculations. Their omission can result in significant errors, relevant for EEG research and clinical diagnosis.

Postnatal diagnosis of single-suture craniosynostosis with cranial ultrasound: a systematic review

INTRODUCTION

The optimal protocol for diagnostic workup of craniosynostosis and the role of specific imaging modalities remain controversial. Skull X-rays and 3-dimensional head CTs are options when physical exam is equivocal but involve ionizing radiation. Ultrasound has emerged as an alternative modality for visualization of cranial sutures, but its use is not widespread.

METHODS

The authors performed a systematic review of the literature on the use of ultrasound for the diagnosis of craniosynostosis.

RESULTS

A total of 12 studies involving 1062 patients were included. Overall, 300 patients (28.2%) were diagnosed with craniosynostosis. A total of 369 (34.7%) patients had their diagnosis (craniosynostosis vs. patent sutures) confirmed with another imaging modality in addition to ultrasound. Among studies, the specificity of ultrasound ranged from 86 to 100%, and the sensitivity from 71 to 100%.

CONCLUSIONS

Ultrasonography of cranial sutures is a feasible and accurate tool for the diagnosis of single-suture craniosynostosis when physical exam findings are insufficient. Although technical aspects of ultrasonography and its interpretation have an associated learning curve, ultrasound can achieve high sensitivity and specificity among patients with suspected craniosynostosis.

Incidence of persistent metopic suture in Australia: findings from 1034 three-dimensional computed tomography scans

PURPOSE

To investigate the incidence of persistent, open metopic sutures in contemporary Australians aged 24 months and older.

METHODS

Metopic suture evaluation was conducted on retrospective cranial/cervical computed tomography scans of patients aged 24 to 252 months who presented to the Women's and Children's Hospital in Adelaide, Australia, between 2010 and 2020. Suture ossification was graded according to Lottering scoring system based on 4 stages, on three-dimensional volume-rendered reconstructions (stage 1: fibrous tissue interface, stage 2: commenced fusion, stage 3: complete fusion and stage 4: obliterated suture). The complete persistent sutures were classified as stage 1. Partially closed sutures were classified into stages 2 and 3, while completely closed sutures were defined as stage 4.

RESULTS

One thousand thirty-four patients (61.2% male and 38.8% female) were included, with a mean age at scan of 66 months. More than half of patients were subject to scanning due to closed-head injuries. The incidence of persistent (completely open) metopic suture was 4.8% (2.3% in males and 2.5% in females). In comparison, a partially closed metopic suture was found in 6.3% of the study cohort, with the remaining sutures located along the metopic suture line, at the glabella, mid-part of the suture, bregma and glabella-bregma areas.

CONCLUSION

The prevalence of persistent metopic sutures in our study of the Australian population is 4.8%, and it is equally distributed between the genders. The pattern of suture closure can commence from any location along the suture line, which is in contrast to the existing literature.

Physiologic Timeline of Cranial-Base Suture and Synchondrosis Closure

BACKGROUND

Fusion of cranial-base sutures/synchondroses presents a clinical conundrum, given their often unclear "normal" timing of closure. This study investigates the physiologic fusion timelines of cranial-base sutures/synchondroses.

METHODS

Twenty-three age intervals were analyzed in subjects aged 0 to 18 years. For each age interval, 10 head computed tomographic scans of healthy subjects were assessed. Thirteen cranial-base sutures/synchondroses were evaluated for patency. Partial closure in greater than or equal to 50 percent of subjects and complete bilateral closure in less than 50 percent of subjects defined the fusion "midpoint." Factor analysis identified clusters of related fusion patterns.

RESULTS

Two hundred thirty scans met inclusion criteria. The sutures' fusion midpoints and completion ages, respectively, were as follows: frontoethmoidal, 0 to 2 months and 4 years; frontosphenoidal, 6 to 8 months and 12 years; and sphenoparietal, 6 to 8 months and 4 years. Sphenosquamosal, sphenopetrosal, parietosquamosal, and parietomastoid sutures reached the midpoint at 6 to 8 months, 8 years, 9 to 11 months, and 12 years, respectively, but rarely completed fusion. The occipitomastoid suture partially closed in less than or equal to 30 percent of subjects. The synchondroses' fusion midpoints and completion ages, respectively, were as follows: sphenoethmoidal, 3 to 5 months and 5 years; spheno-occipital, 9 years and 17 years; anterior intraoccipital, 4 years and 10 years; and posterior intraoccipital, 18 to 23 months and 4 years. The petro-occipital synchondrosis reached the midpoint at 11 years and completely fused in less than 50 percent of subjects. Order of fusion of the sutures, but not the synchondroses, followed the anterior-to-posterior direction. Factor analysis suggested three separate fusion patterns.

CONCLUSIONS

The fusion timelines of cranial-base sutures/synchondroses may help providers interpret computed tomographic data of patients with head-shape abnormalities. Future work should elucidate the mechanisms and sequelae of cranial-base suture fusion that deviates from normal timelines.

Anthropometric cranial measurements in metopic craniosynostosis/trigonocephaly: diagnostic criteria, classification of severity and indications for surgery

ABSTRACT

Metopic craniosynostosis is the second most frequent type of craniosynostosis. When the phenotypic presentation has been deemed severe the treatment is surgical in nature and is performed in infancy with fronto-orbital advancement and cranial vault remodeling. At the time of this writing, there is no consensus regarding an objective evaluation system for severity, diagnostic criteria, or indications for surgery. This study aims to review the anthropometric cranial measurements and the relative diagnostic criteria/classification of severity/surgical indications proposed so far for this skull malformation, and to investigate if there is any scientific support for their utility.

Aberrant Morphologic Patterning of Combined Sagittal and Metopic Craniosynostosis

ABSTRACT

Combined sagittal and metopic craniosynostosis is an uncommon condition that may result in a wide spectrum of cranial morphologies. This occurs as a result of the compound effects of both prematurely fused sutures. The authors present an incidence of sagittal craniosynostosis with a specific altered head morphology, and delayed diagnosis that the authors believe occurred due to structural changes associated with concurrent metopic suture synostosis This patient underscores the limitations of relying on classic diagnostic patterns and highlights the critical role of noninvasive imaging in the diagnosis of craniosynostosis.

Part 1: Surgical Correction in 231 Trigonocephaly Patients - The Alder Hey Experience

ABSTRACT

Isolated metopic synostosis presents with a range of severity, from a palpable ridge as the sole presenting feature to a constellation of features resulting in trigonocephaly. At our unit, patients on the moderate to severe end of the phenotypic spectrum of trigonocephaly are offered fronto-orbital advancement and remodeling. The authors present our series of trigonocephaly patients who have undergone surgical correction. From January 2000 to January 2020, the authors operated on 231 patients with trigonocephaly. The average age at surgery was 18 months, with an average follow-up of 77.4 months. Seventy-nine percent of patients had no comorbidity. Ten percent of patients sustained a dural tear with no long-term consequences. The total early complication rate was 12.1%. The most common early complications were wound infection and wound dehiscence at 7.4% and 3.9% respectively. The total reoperation rate was 6.5%. The introduction of infection prevention and control measures over the 2 decades at our unit reduced the reoperation rate to 1.1%. The most common late complication was temporal recession in 20.8% of patients, none of whom required aesthetic correction. The recurrence rate of a metopic ridge was 2.3% with no patients requiring further surgery. None of our patients required calvarial remodeling for raised intracranial pressure after the primary fronto-orbital advancement and remodeling. There were no life-threatening complications or mortalities in our cohort. The authors present recommendations which include an infection control care bundle, cessation of surgical drains, and practice adjustments to reduce risks of infection and risk of requiring further calvarial remodelling for raised intracranial pressure.

Premature Fusion of the Sagittal Suture as an Incidental Radiographic Finding in Young Children

BACKGROUND

Craniosynostosis typically develops prenatally and creates characteristic changes in craniofacial form. Nevertheless, postnatal forms of craniosynostosis have been described. The purpose of this study was to determine the prevalence of incidentally identified, but temporally premature, cranial suture fusion in normocephalic children.

METHODS

Computed tomographic scans obtained from children aged 1 to 5 years evaluated in the authors' emergency department between 2005 and 2016 were reviewed for evidence of craniosynostosis. Patients with prior ventriculoperitoneal shunt, brain or cranial abnormality, or known syndromes were excluded. The presence of craniosynostosis and cranial index was assessed by a panel of three craniofacial surgeons and one pediatric neurosurgeon. Demographic information, fusion type, reason for the computed tomographic scan, and medical history were recorded as covariates. Cranial shape and intracranial volume were calculated using previously validated automated system.

RESULTS

Three hundred thirty-one patients met the inclusion criteria. The mean age was 2.4 ± 1.3 years. Eleven patients (3.3 percent) were found to have a complete (n = 9) or partial (n = 2) fusion of the sagittal suture. All patients had a normal cranial index (0.80; range, 0.72 to 0.87) and a grossly normal head shape. Only two fusions (18.2 percent) were documented by the radiologist. Cranial shape analysis performed in five of the 11 patients showed subtle phenotypic changes along the scaphocephaly spectrum in four patients, with a normal shape in the remaining case.

CONCLUSIONS

Sagittal fusion is present in 3.3 percent of otherwise phenotypically normal children aged 1 to 5 years. The clinical significance of this result is unclear, but routine screening of affected patients is paramount.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, IV.

Diagnosis and Management of Suture-Related Concerns of the Infant Skull

The cranial fontanelles and sutures have several benign variations, including most cases of "early" or "late" closure of the anterior fontanelle, bathrocephaly, overriding sutures, and benign metopic ridging. However, recognizing true craniosynostosis and referring the patient to a craniofacial specialist in a timely fashion are imperative, as minimally invasive options can be offered to most patients younger than 6 months of age. Gaining comfort with the physical examination of an infant with an abnormal head shape is best achieved through experience and pattern recognition and will frequently facilitate an accurate diagnosis without the need for ionizing radiation.

Establishment of Objective Clinical Parameters for Assessment of Trigonocephaly: Are Caliper-Derived Clinical Measures Adequate?

OBJECTIVE

Objective clinical parameters characterizing the severity of trigonocephaly are essential given the concern for computerized tomography (CT) scans and radiation in infants. The present study seeks to develop a clinical tool by which to characterize trigonocephaly.

DESIGN

Retrospective cohort study.

SETTING

Tertiary academically affiliated children's medical center.

PARTICIPANTS

A retrospective review identified patients with trigonocephaly for whom surgery was recommended (group 1) and those with metopic ridging without significant trigonocephaly (group 2). Normal age-matched controls were also evaluated (group 3).

INTERVENTIONS

Cranial vault caliper measurements were compared across groups. Two ratios measuring anterior vault constriction were developed: (1) bitemporal width at the mid-forehead to the biparietal width, and (2) bitemporal width at the lateral brow to the biparietal width.

MAIN OUTCOME MEASURES

Bitemporal width to biparietal width (ratio).

RESULTS

Caliper measures were obtained from 19 patients in group 1, 8 patients in group 2, and 19 patients in group 3 (controls). Cranial indices were not significantly different across groups. The bitemporal width at the mid-forehead to the biparietal width ratio was significantly lower in group 1, with no difference between groups 2 and 3. The bitemporal width at the lateral brow to the biparietal width ratio was significantly different between all 3 groups, with group 1 < group 2 < group 3, respectively.

CONCLUSIONS

Bitemporal to biparietal ratios are a quantitative, objective clinical measure that can be used to differentiate patients with significant trigonocephaly from those with metopic ridging but no significant cranial deformity. These findings suggest that caliper-derived indices can assist in characterizing surgically relevant cranial vault deformities secondary to metopic synostosis and may circumvent CT-based analysis.

Three-Dimensional Analysis and Surgical Planning for Open Correction of Trigonocephaly

SUMMARY

Metopic craniosynostosis results in trigonocephaly, characterized by a triangular forehead with metopic ridge, bitemporal pinching, and narrow-set eyes with recessed lateral orbital rims. Surgical management is controversial but may include open expansion and vault remodeling, to enhance neurocognitive and aesthetic outcomes. This article and video vignette depict the diagnosis and treatment of metopic craniosynostosis, demonstrating the senior author's open approach, three-dimensional virtual surgical planning, and technical steps.

Clinical application of "black bone" imaging in paediatric craniofacial disorders

For decades, CT has been the primary imaging modality for the diagnosis and surveillance of paediatric craniofacial disorders. However, the deleterious effects of ionising radiation in the paediatric population are well established and remain an ongoing concern. This is especially so in the head and neck region, which has relatively poor soft tissue shielding with many radiosensitive organs. The development of "black bone" imaging utilising low flip angles and short echo time (TE) has shown considerable promise in alleviating the use of ionising radiation in many cases of craniofacial disorders. In this review article, we share our experience of utilising "black bone" sequence in children with craniofacial pathologies, ranging from traumatic injuries to craniosynostosis and focal osseous/fibro-osseous lesions such as fibrous dysplasia and Langerhans cell histiocytosis (LCH). A detailed discussion on the technical aspects of "black bone" sequence, including its potential pitfalls and limitations, will also be included.

Using Sensitivity Analysis to Develop a Validated Computational Model of Post-operative Calvarial Growth in Sagittal Craniosynostosis

Craniosynostosis is the premature fusion of one or more sutures across the calvaria, resulting in morphological and health complications that require invasive corrective surgery. Finite element (FE) method is a powerful tool that can aid with preoperative planning and post-operative predictions of craniosynostosis outcomes. However, input factors can influence the prediction of skull growth and the pressure on the growing brain using this approach. Therefore, the aim of this study was to carry out a series of sensitivity studies to understand the effect of various input parameters on predicting the skull morphology of a sagittal synostosis patient post-operatively. Preoperative CT images of a 4-month old patient were used to develop a 3D model of the skull, in which calvarial bones, sutures, cerebrospinal fluid (CSF), and brain were segmented. Calvarial reconstructive surgery was virtually modeled and two intracranial content scenarios labeled “CSF present” and “CSF absent,” were then developed. FE method was used to predict the calvarial morphology up to 76 months of age with intracranial volume-bone contact parameters being established across the models. Sensitivity tests with regards to the choice of material properties, methods of simulating bone formation and the rate of bone formation across the sutures were undertaken. Results were compared to the in vivo data from the same patient. Sensitivity tests to the choice of various material properties highlighted that the defined elastic modulus for the craniotomies appears to have the greatest influence on the predicted overall skull morphology. The bone formation modeling approach across the sutures/craniotomies had a considerable impact on the level of contact pressure across the brain with minimum impact on the overall predicated morphology of the skull. Including the effect of CSF (based on the approach adopted here) displayed only a slight reduction in brain pressure outcomes. The sensitivity tests performed in this study set the foundation for future comparative studies using FE method to compare outcomes of different reconstruction techniques for the management of craniosynostosis.

The 25 Most Cited Articles in The Journal of Craniofacial Surgery: A Study Based on the Web of Science From 1995 to 2020

ABSTRACT

The aim of this study was to identified and analyzed the top 25 most cited articles among the articles published in The Journal of Craniofacial Surgery (J Craniofac Surg) from 1995 to 2020 in the Web of Science database. Using the advanced search section in the Web of Science, all articles published in the J Craniofac Surg were listed. The distribution of the numbers of publications by years was determined. It was determined that a total of 11,888 articles were published in the J Craniofac Surg between 1995 and 2020. A total of 84,218 citations were made to these articles, and the h-index of these articles was 73. The top 25 most cited articles were determined. The top three countries that made the most cited to these 25 articles were the USA (n: 1112), China (n: 292), and Germany (n: 251), respectively. The top three journals that made the most cited to these 25 articles were the J Craniofac Surg (n: 378), Plast Reconstr Surg (n: 179), and J Oral Maxillofac Surg (n: 120), respectively. The authors think that this study may benefit researchers in this field by identifying the most cited articles in the J Craniofac Surg.

Craniosynostosis: current conceptions and misconceptions

Cranial bones articulate in areas called sutures that must remain patent until skull growth is complete. Craniosynostosis is the condition that results from premature closure of one or more of the cranial vault sutures, generating facial deformities and more importantly, skull growth restrictions with the ability to severely affect brain growth. Typically, craniosynostosis can be expressed as an isolated event, or as part of syndromic phenotypes. Multiple signaling mechanisms interact during developmental stages to ensure proper and timely suture fusion. Clinical outcome is often a product of craniosynostosis subtypes, number of affected sutures and timing of premature suture fusion. The present work aimed to review the different aspects involved in the establishment of craniosynostosis, providing a close view of the cellular, molecular and genetic background of these malformations.

Emissary veins and pericerebral cerebrospinal fluid in trigonocephaly: do they define a specific subtype?

INTRODUCTION

The premature fusion of the metopic suture may be associated with the presence of emissary veins (EV) and abnormally large pericerebral cerebrospinal fluid (CSF) spaces which suggest an associated focal disturbance in CSF dynamics. The incidence of such findings and their potential significance in terms of management of the disease have not been fully elucidated. The aim of this study is to investigate whether these phenomena identify specific subtypes of trigonocephaly. In such a direction, we evaluated the volume of the pericerebral CSF spaces and their relationship to the morphology ("Ω," "V," or flat type) of the prematurely fused metopic suture and to the value of the interfrontal angle value on the grounds of computed tomographic (CT) scan examinations.

METHOD

The preoperative brain CT scans of 74 children (52 boys, 22 girls) with trigonocephaly who had undergone fronto-orbital remodeling were evaluated. The volume of the pericerebral CSF spaces and the value of the interfrontal angle were calculated. The type of intracranial notch was studied and classified according to its shape on the preoperative CT scan: a groove "Ω," a ridge/"V" ridge or absent when flat and evidence of emissary veins related to the abnormally fused suture.

RESULTS

Preoperatively, an endocranial metopic groove or ridge was seen in 70% of the children. Emissary veins were identified in 34 of 74 patients (45%), at a mean distance of 2.04 cm (1.18-2.94 cm) from the nasion. The presence of large pericerebral CSF spaces significantly correlated with the presence of EV (p < 0.05), with the "Ω" type (p < 0.05) and with interfrontal angles under 134° (p < 0.005).

CONCLUSIONS

Metopic suture early fusion shows an association between EV, pericerebral CSF spaces, and the "Ω" groove appearance of the suture. This association identifies a specific subgroup in which the presence of emissary veins and large pericerebral CSF spaces is an indicator of local venous hypertension due to the sagittal sinus constriction within an osseous groove created by the abnormal suture fusion process. The implications for the surgical management and long-term results as compared to trigonocephalic children with small or absent normal peripheral spaces and EV are still to be determined.

New method for quantification of the relative severity and (a)symmetry of isolated metopic synostosis

Trigonocephaly is the result of premature fusion of the metopic suture and its severity can vary widely. However, there is no gold standard for quantification of the severity. This study was performed to quantify severity using the Utrecht Cranial Shape Quantifier (UCSQ) and to assess forehead symmetry. Nineteen preoperative non-syndromic trigonocephaly patients (age ≤1 year) were included for the analysis of severity and symmetry. Severity according to the UCSQ was based on the following combined variables: forehead width and relative skull elongation. The UCSQ was compared to the most established quantification methods. A high correlation was found between the UCSQ and visual score (r=0.71). Moderate to negligible correlation was found between the UCSQ and frontal angle, binocular distance, inter-ocular distance, and frontal stenosis. Additionally, correlation between the visual score and these established quantification methods was negligible. Assessment of the frontal peak (a)symmetry (ratio of right to left triangle area in the curve) showed a mean right versus left triangle area ratio of 1.4 (range 0.9-2.4). The results suggest that the UCSQ is appropriate for the quantification of severity based on the high correlation with clinical judgement. Furthermore, a larger triangle area right than left was unexpectedly found, indicating forehead asymmetry.

Distinguishing craniomorphometric characteristics and severity in metopic synostosis patients

The decision about which metopic synostosis patients should undergo surgery remains controversial. Multiple measures for radiographic severity have been developed in order to determine the optimal criteria for treatment. The aim of this study was to perform an extensive craniomorphometric analysis of patients who underwent surgery for metopic synostosis to validate and compare the various severity scales developed for this non-syndromic craniosynostosis. A comparative morphometric analysis was performed using computed tomography scans of preoperative metopic synostosis patients (n=167) and normal controls (n=44). Measurements included previous and newly developed metopic severity indices. Volumetric and area analyses were used to determine the degree of anterior cranial area and potential volume restrictions. Of the severity indices measured, the frontal angle, endocranial bifrontal angle (EBF), adjusted EBF (aEBF), anterior cranial fossa angle, horizontal cone angle, and bitemporal/biparietal distance ratio were significantly different in the metopic subjects relative to controls overall. However, metopic index, orbital rim angle, foramen ovale distance, and cranial volume exhibited no significant difference from controls. Only the frontal angle and aEBF correlated with the changes in anterior cranial dimensions observed in metopic synostosis. In conclusion, the frontal angle and aEBF provide the most accurate measures of severity in metopic synostosis.

Pharmacological targeting of KDM6A and KDM6B, as a novel therapeutic strategy for treating craniosynostosis in Saethre-Chotzen syndrome

BACKGROUND

During development, excessive osteogenic differentiation of mesenchymal progenitor cells (MPC) within the cranial sutures can lead to premature suture fusion or craniosynostosis, leading to craniofacial and cognitive issues. Saethre-Chotzen syndrome (SCS) is a common form of craniosynostosis, caused by TWIST-1 gene mutations. Currently, the only treatment option for craniosynostosis involves multiple invasive cranial surgeries, which can lead to serious complications.

METHODS

The present study utilized Twist-1 haploinsufficient (Twist-1^del/+) mice as SCS mouse model to investigate the inhibition of Kdm6a and Kdm6b activity using the pharmacological inhibitor, GSK-J4, on calvarial cell osteogenic potential.

RESULTS

This study showed that the histone methyltransferase EZH2, an osteogenesis inhibitor, is downregulated in calvarial cells derived from Twist-1^del/+ mice, whereas the counter histone demethylases, Kdm6a and Kdm6b, known promoters of osteogenesis, were upregulated. In vitro studies confirmed that siRNA-mediated inhibition of Kdm6a and Kdm6b expression suppressed osteogenic differentiation of Twist-1^del/+ calvarial cells. Moreover, pharmacological targeting of Kdm6a and Kdm6b activity, with the inhibitor, GSK-J4, caused a dose-dependent suppression of osteogenic differentiation by Twist-1^del/+ calvarial cells in vitro and reduced mineralized bone formation in Twist-1^del/+ calvarial explant cultures. Chromatin immunoprecipitation and Western blot analyses found that GSK-J4 treatment elevated the levels of the Kdm6a and Kdm6b epigenetic target, the repressive mark of tri-methylated lysine 27 on histone 3, on osteogenic genes leading to repression of Runx2 and Alkaline Phosphatase expression. Pre-clinical in vivo studies showed that local administration of GSK-J4 to the calvaria of Twist-1^del/+ mice prevented premature suture fusion and kept the sutures open up to postnatal day 20.

CONCLUSION

The inhibition of Kdm6a and Kdm6b activity by GSK-J4 could be used as a potential non-invasive therapeutic strategy for preventing craniosynostosis in children with SCS. Pharmacological targeting of Kdm6a/b activity can alleviate craniosynostosis in Saethre-Chotzen syndrome. Aberrant osteogenesis by Twist-1 mutant cranial suture mesenchymal progenitor cells occurs via deregulation of epigenetic modifiers Ezh2 and Kdm6a/Kdm6b. Suppression of Kdm6a- and Kdm6b-mediated osteogenesis with GSK-J4 inhibitor can prevent prefusion of cranial sutures.

Distinguishing Between Lambdoid Craniosynostosis and Deformational Plagiocephaly: A Review of This Paradigm Shift in Clinical Decision-Making and Lesson for the Future

The cause of occipital asymmtery can be either extrinsic or intrinsic. Intrinsic causes include lambdoid craniosynsotosis. This condition is generally treated with cranial vault expansion surgery. Extrinsic causes include deformational plagiocephaly, which became commonplace after the "Back to Sleep Campaign" instituted in the 1980s by the American Academy of Pediatrics. The treatment of this condition is non surgical. Dr. Joseph Gruss was instumental in differentiating between these conditions and reducing the number of unnecessary surgeries that were previously being performed.

School-Aged Anthropometric Outcomes After Endoscopic or Open Repair of Metopic Synostosis

BACKGROUND AND OBJECTIVES

Metopic craniosynostosis can be treated by fronto-orbital advancement or endoscopic strip craniectomy with postoperative helmeting. Infants younger than 6 months of age are eligible for the endoscopic repair. One-year postoperative anthropometric outcomes have been shown to be equivalent, with significantly less morbidity after endoscopic treatment. The authors hypothesized that both repairs would yield equivalent anthropometric outcomes at 5-years postoperative.

METHODS

This study was a retrospective chart review of 31 consecutive nonsyndromic patients with isolated metopic craniosynostosis treated with either endoscopic or open correction. The primary anthropometric outcomes were frontal width, interfrontal divergence angle, the Whitaker classification, and the presence of lateral frontal retrusion. Peri-operative variables included estimated blood loss, rates of blood transfusion, length of stay, and operating time.

RESULTS

There was a significantly lower rate of lateral frontal retrusion in the endoscopic group. No statistically significant differences were found in the other 3 anthropometric outcomes at 5-years postoperative. The endoscopic group was younger at the time of surgery and had improved peri-operative outcomes related to operating time, hospital stay and blood loss. Both groups had low complication and reoperation rates.

CONCLUSIONS

In our cohort of school-aged children with isolated metopic craniosynostosis, patients who underwent endoscopic repair had superior or equivalent outcomes on all 4 primary anthropometric measures compared with those who underwent open repair. Endoscopic repair was associated with significantly faster recovery and decreased morbidity. Endoscopic repair should be considered in patients diagnosed with metopic craniosynostosis before 6 months of age.

Identifying the Misshapen Head: Craniosynostosis and Related Disorders

Pediatric care providers, pediatricians, pediatric subspecialty physicians, and other health care providers should be able to recognize children with abnormal head shapes that occur as a result of both synostotic and deformational processes. The purpose of this clinical report is to review the characteristic head shape changes, as well as secondary craniofacial characteristics, that occur in the setting of the various primary craniosynostoses and deformations. As an introduction, the physiology and genetics of skull growth as well as the pathophysiology underlying craniosynostosis are reviewed. This is followed by a description of each type of primary craniosynostosis (metopic, unicoronal, bicoronal, sagittal, lambdoid, and frontosphenoidal) and their resultant head shape changes, with an emphasis on differentiating conditions that require surgical correction from those (bathrocephaly, deformational plagiocephaly/brachycephaly, and neonatal intensive care unit-associated skill deformation, known as NICUcephaly) that do not. The report ends with a brief discussion of microcephaly as it relates to craniosynostosis as well as fontanelle closure. The intent is to improve pediatric care providers' recognition and timely referral for craniosynostosis and their differentiation of synostotic from deformational and other nonoperative head shape changes.

Gain-of-function variants and overexpression of RUNX2 in patients with nonsyndromic midline craniosynostosis

Craniosynostosis (CS), the premature fusion of one or more cranial sutures, is a relatively common congenital anomaly, occurring in 3-5 per 10,000 live births. Nonsyndromic CS (NCS) accounts for up to 80% of all CS cases, yet the genetic factors contributing to the disorder remain largely unknown. The RUNX2 gene, encoding a transcription factor critical for bone and skull development, is a well known CS candidate gene, as copy number variations of this gene locus have been found in patients with syndromic craniosynostosis. In the present study, we aimed to characterize RUNX2 to better understand its role in the genetic etiology and in the molecular mechanisms underlying midline suture ossification in NCS. We report four nonsynonymous variants, one intronic variant and one 18 bp in-frame deletion in RUNX2 not found in our study control population. Significant difference in allele frequency (AF) for the deletion variant RUNX2 p.Ala84-Ala89del (ClinVar 257,095; dbSNP rs11498192) was observed in our sagittal NCS cohort when compared to the general population (P = 1.28 × 10^-6), suggesting a possible role in the etiology of NCS. Dual-luciferase assays showed that three of four tested RUNX2 variants conferred a gain-of-function effect on RUNX2, further suggesting their putative pathogenicity in the tested NCS cases. Downregulation of RUNX2 expression was observed in prematurely ossified midline sutures. Metopic sites showed significant downregulation of promoter 1-specific isoforms compared to sagittal sites. Suture-derived mesenchymal stromal cells showed an increased expression of RUNX2 over matched unfused suture derived cells. This demonstrates that RUNX2, and particularly the distal promoter 1-isoform group, are overexpressed in the osteogenic precursors within the pathological suture sites.

Long-Term Growth following Trigonocephaly Repairs: Are Overcorrections Necessary?

BACKGROUND

Does bifrontal width change with growth following trigonocephaly corrections? Postoperative long-term growth was assessed, along with the impacts of phenotypic severity, surgical timing, and operative technique, to determine how wide to surgically set bifrontal width.

METHODS

A retrospective review of all trigonocephaly repairs was performed. Exclusion criteria included syndromic conditions, incomplete records, and follow-up under 1 year. Anthropometric measurements taken through completion of growth were evaluated and compared to sex- and age-matched normal standards for Z score conversion.

RESULTS

Of 370 consecutive patients undergoing repairs, 95 had sufficient anthropometric data. The mean surgical age was 10.8 months (range, 2 months to 7 years) and mean follow-up was 54.3 months (range, 12 months to 17.8 years). Sequential measurements revealed progressive increases in bifrontal width. However, following conversion to Z scores, the initial overcorrection (mean overcorrection, 8.7 mm; mean Z score, +2.3) steadily diminished to an undercorrection (mean measurement, -5.5 mm; mean Z score, -1.1). Compared to treatment at an older age (10 to 12 months), repairs performed in those younger than 8 months showed worse growth (p = 0.004). Those more severely affected (lowest bifrontal Z scores) had growth similar to that of those more mildly impacted. Only two patients (2.1 percent) underwent secondary procedures for recurrences. No correlation was found between anthropologic measurements and observers' severity assessments.

CONCLUSIONS

Subnormal bifrontal growth occurs following trigonocephaly corrections, especially with earlier corrections. Repairs performed at approximately 11 months of age had to be overcorrected by approximately 1.5 cm to produce a normal bifrontal width at maturity.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Craniofacial Sutural Pattern and Surgical Management in Patients With Different Degrees of Trigonocephaly Severity

The aim of this study was to identify quantitative tools to classify the severity of trigonocephaly to guide surgical management and predict outcome.

METHODS

We reviewed high-resolution computed tomography images of 59 patients with metopic synostosis. We assessed the craniofacial sutural pattern as well as interfrontal and metopic angles, and we related the frontal angulation degree with the sutural pattern, the surgical management, and clinical outcome.

RESULTS

We identified 3 groups according to the severity of trigonocephaly. No difference was found between the sutural pattern of nasion complex and severity, whereas the closure of zygomatic maxillary sutures increased with the severity degree (P < 0.05). The operative management was related to the severity degree (P < 0.001) and to the reduced age (P = 0.009).

CONCLUSIONS

Interfrontal and metopic angles are complementary measurements to evaluate with high accuracy the degree of frontal angulation. In preoperative assessment, they may guide surgery decision in particular when the choice is not straightforward.