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.

In Vitro Assessment of the Neuro-Compatibility of Fe-20Mn as a Potential Bioresorbable Material for Craniofacial Surgery.

Background and Objectives: Spring-assisted surgery is a popular option for the treatment of non-syndromic craniosynostosis. The main drawback of this procedure is the need for a second surgery for spring removal, which could be avoided if a distractor material could be metabolised over time. Iron-Manganese alloys (FeMn) have a good trade-off between degradation rate and strength; however, their biocompatibility is still debated. Materials and Methods: In this study, the neuro-compatibility of Fe-20Mn (wt.%) was assessed using standard assays. PC-12 cells were exposed to Fe-20Mn (wt.%) and stainless steel via indirect contact. To examine the cytotoxicity, a Cell Tox Green assay was carried out after 1, 2, and 3 days of incubation. Following differentiation, a neurite morphological examination after 1 and 7 days of incubation time was carried out. The degradation response in modified Hank's solution at 1, 3, and 7 days was investigated, too. Results: The cytotoxicity assay showed a higher toxicity of Fe-20Mn than stainless steel at earlier time points; however, at the latest time point, no differences were found. Neurite morphology was similar for cells exposed to Fe-20Mn and stainless steel. Conclusions: In conclusion, the Fe-20Mn alloy shows promising neuro-compatibility. Future studies will focus on in vivo studies to confirm the cellular response to Fe-20Mn.

A rare case of atlantoaxial rotatory fixation after posterior calvarial vault expansion surgery in a Crouzon patient.

INTRODUCTION: Atlantoaxial rotatory fixation (AARF) is a rare condition that occurs most commonly in children. The torticollis caused by AARF usually presents as abnormal posturing of the head and neck, with rotation of the chin to the opposite side. AARF in children could occur due to congenital bony malformation, minor trauma, upper respiratory tract infections (Grisel's syndrome), postoperatively after head and neck (ENT) surgery, and unknown reasons. AARF in the postoperative patient is a rare and poorly understood entity. METHODS: The authors present a case report of a 2-year-old boy with Crouzon Syndrome undergoing posterior calvarial vault expansion (PVE) surgery that developed AARF as a complication. RESULTS: The authors believe that cranial vault surgery should be considered a potential risk procedure for AARF, especially if it is done in susceptible populations (syndromic craniosynostosis patients) with other underlying sequelae (tonsillar ectopia or syringomyelia). During surgery, careful attention should be paid to maintaining a neutral alignment of the patient's cervical spine as rotatory movements under anaesthesia and muscle relaxation may be contributory factors. CONCLUSION: AARF should be suspected and investigated in children with painful torticollis after craniofacial surgery.

Skull fractures in abusive head trauma: a single centre experience and review of the literature.

PURPOSE: The authors provide a comprehensive framework with which to approach paediatric calvarial injury sustained as a result of suspected abusive head trauma (AHT). This is achieved through the presentation of a case series set in the context of the unique morphology of the infant skull and the possible diagnostic pitfalls which may arise due to the presence of variant anatomy or other mimicking conditions. METHODS: A retrospective analysis of sixty-three patients referred to our institution with suspected AHT was carried out. Seventeen patients with skull fractures were identified and their fractures were described in terms of anatomical location, type and course. Our data was then interpreted in the light of known anatomical fracture mimics and the available literature on the subject. RESULTS: Forty-two skull fractures were identified and described in our cohort, most of which were simple linear fractures of the parietal bones (33%). There were also a substantial number of complex stellate fractures, namely of the parietal (29%) and occipital (10%) bones. Eleven fracture mimics including accessory sutures and wormian bones were also identified in this cohort. CONCLUSIONS: Our study supports and builds on the existing literature, thereby offering a more complete view of the spectrum of calvarial damage sustained as a result of AHT in the context of its diagnostic pitfalls.

Early Recognition of Raised Intracranial Pressure in Craniosynostosis Using Optical Coherence Tomography.

OBJECTIVE: Craniosynostosis can be associated with raised intracranial pressure (ICP), which can pose deleterious effects on the brain and vision if untreated. Estimating ICP in children is challenging, whilst gold standard direct intracranial measurement of ICP is invasive and carries risk. This systematic review aims to evaluate the role of optical coherence tomography (OCT), a noninvasive imaging technique, for detecting raised ICP in children with craniosynostosis. METHODS: The authors conducted a systematic review of the literature published from inception until 19 August, 2019 in the Cochrane Central Register of Controlled Trials, PubMed, MEDLINE, and EMBASE. Eligible studies evaluated the role of OCT in detecting raised ICP in children aged 0 to 16 years with craniosynostosis. Main outcome measures were sensitivity and specificity of OCT parameters for raised ICP. Quality assessment was performed using the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-sectional Studies. RESULTS: Out of 318 records identified, data meeting the inclusion criteria were obtained from 3 studies. The quality of 2 studies was poor whilst 1 was fair. Optical coherence tomography demonstrated higher sensitivity and specificity for detecting raised ICP compared to fundus examination, clinical history, radiological testing, and visual field testing. CONCLUSIONS: This systematic review demonstrated a lack of quality evidence for OCT as a screening tool for children with craniosynostosis. Further research is required to clarify the strength of OCT in this role and to determine which OCT parameters are most appropriate.

The Science Behind the Springs: Using Biomechanics and Finite Element Modeling to Predict Outcomes in Spring-Assisted Sagittal Synostosis Surgery.

Spring-assisted surgery for the correction of scaphocephaly has gained popularity over the past 2 decades. Our unit utilizes standardized torsional springs with a central helix for spring-assisted surgery. This design allows a high degree of accuracy and reproducibility of the force vectors and force distance curves. In this manuscript, we expand on the biomechanical testing and properties of these springs. Standardization of design has enabled us to study the springs on bench and in vivo and a comprehensive repository of calvarial remodeling and spring dynamics has been acquired and analyzed.Finite element modeling is a technique utilized to predict the outcomes of spring-assisted surgery. We have found this to be a useful tool, in planning our surgical strategy and improving outcomes. This technique has also contributed significantly to the process of informed consent preoperatively. In this article, we expand on our spring design and dynamics as well as the finite element modeling used to predict and improve outcomes.In our unit, this practice has led to a significant improvement in patient outcomes and parental satisfaction and we hope to make our techniques available to a wider audience.

Three-Dimensional Calvarial Growth in Spring-Assisted Cranioplasty for Correction of Sagittal Synostosis.

Spring-assisted cranioplasty (SAC) is a minimally invasive technique for treating sagittal synostosis in young infants. Yet, follow-up data on cranial growth in patients who have undergone SAC are lacking. This project aimed to understand how the cranial shape develops during the postoperative period, from spring insertion to removal. 3D head scans of 30 consecutive infants undergoing SAC for sagittal synostosis were acquired using a handheld scanner pre-operatively, immediately postoperatively, at follow-up and at spring removal; 3D scans of 41 age-matched control subjects were also acquired. Measurements of head length, width, height, circumference, and volume were taken for all subjects; cephalic index (CI) was calculated. Statistical shape modeling was used to compute 3D average head models of sagittal patients at the different time points. SAC was performed at a mean age of 5.2 months (range 3.3-8.0) and springs were removed 4.3 months later. CI increased significantly (P < 0.001) from pre-op (69.5% ±â€Š2.8%) to spring removal (74.4% ±â€Š3.9%), mainly due to the widening of head width, which became as wide as for age-matched controls; however, the CI of controls was not reached (82.3% ±â€Š6.8%). The springs did not constrain volume changes and allowed for natural growth. Population mean shapes showed that the bony prominences seen at the sites of spring engagement settle over time, and that springs affect the overall 3D head shape of the skull. In conclusion, results reaffirmed the effectiveness of SAC as a treatment method for nonsyndromic single suture sagittal synostosis.

Pediatric Congenital Anterior Skull Base Encephaloceles and Surgical Management: A Comparative Review of 22 Patients Treated Transnasally, Transcranially, or Combined Approach With a Review of the Literature.

BACKGROUND AND OBJECTIVES: Anterior basal encephaloceles are considered a rare entity and are often associated with midline cerebral abnormalities. Those with a large skull base defect and herniation of brain parenchyma in the neonate or young infant present unique challenges for surgical management. METHODS: We analyzed the neurosurgical administrative and operative databases between 1986 and 2022 to determine clinical presentation, operative approach, and outcome of basal encephaloceles. RESULTS: Over the 36-year period, 27 pediatric anterior basal encephaloceles were managed, of which 22 had full documentation and images allowing comprehensive review. Mean age at presentation was 5 years (SD 4.94). The majority were transethmoidal encephaloceles (59%), followed by the transsphenoidal-sphenoethmoidal type (32%). Overall, 91% were managed surgically by a transcranial, endoscopic, or combined approach. Four children required subsequent procedures, predominantly for persistent cerebrospinal fluid leak. No significant differences in proportion of patients requiring interval/revision surgery after initial conservative, endoscopic endonasal, or transcranial surgery was identified. Neither age at surgery nor size of the defect on computed tomography scan was associated with the need for revision surgery. Size of cranial defect was significantly smaller in the endoscopic group ( P = .01). There was a historic tendency for younger children with larger defects to have a transcranial approach. With the addition of endoscopic skull base expertise, smaller defects in older children were more recently treated endoscopically. CONCLUSION: Basal encephaloceles are rare and complex lesions and are optimally managed within a skull base multidisciplinary team able to provide multiple approaches. Large skull base defects with brain parenchymal involvement often require a transcranial or combined transcranial-endoscopic approach.

The role of reoperation in pediatric cerebellar pilocytic astrocytoma.

OBJECTIVE: Cerebellar pilocytic astrocytomas (cPAs) in childhood have long been recognized to have a good prognosis after total resection, but the outcome after incomplete resective surgery remains largely unpredictable, with the incidence of radiological progressive disease ranging from 18% to 100%. It has been traditionally thought that gross-total resection was required for long-term survival, and small residuals were classically resected in a subsequent operation. METHODS: The authors analyzed their pediatric low-grade glioma (PLGG) database for cases treated between 1985 and 2020 and filtered for intracranial PAs, to determine what clinical or radiological factors precipitated revisional resective surgery in their single quaternary care center cohort. RESULTS: Using the pediatric low-grade glioma database, 283 patients were identified to have a histopathological diagnosis of intracranial PA between 1985 and 2020, of which 200 lesions were within the cerebellum (70.7%). The majority of patients with cPA were between 1 and 10 years of age (n = 145, 72.5%) without gender predominance (M/F = 99:101), usually presenting with 1 lesion (n = 197, 98.5%). Gross-total resection was achieved in 74.5% (n = 149) of initial surgeries for cPA. In patients with subtotal resection, the mean largest diameter of the postoperative residual tumor was 1.06 cm (range 0-2.95 cm). Seven patients with subtotal resection did not require a second resective intervention. In 31 patients the neuro-oncology multidisciplinary team recommended a second resection at a mean time interval of 22.9 months (range 0.13-81.6 months) from the initial surgery. Proportionally, the children who underwent multiple resections were also more likely to receive adjuvant chemo/radiotherapy. Functionally, the children in the multiple operation cohort experienced more complications of therapy including ongoing endocrinopathy, treatment-associated hearing deficit, and neurocognitive deficits. CONCLUSIONS: Residual disease in cPA should be maintained under clinicocoradiological surveillance postoperatively with adoption of a more conservative approach when residual disease is not significantly changing over time.

Intraoperative MRI in pediatric epilepsy and neuro-oncology: a systematic review and meta-analysis.

OBJECTIVE: Intraoperative magnetic resonance imaging (iMRI) use is becoming increasingly widespread in neurosurgical practice, and most of the data reporting its use are in adult populations. There is less evidence on the use of iMRI in pediatric neurosurgery. The aim of this paper was to synthesize the available literature into a systematic review and meta-analysis to evaluate the evidence for iMRI in pediatric neurosurgery, with a particular focus on neuro-oncology and epilepsy surgery. METHODS: This review was registered on PROSPERO and conducted according to PRISMA guidelines. A comprehensive search strategy of Medline via Ovid and Embase was conducted with predetermined key terms. Studies in English reporting the outcomes of patients < 21 years of age who underwent neuro-oncological or epilepsy surgery with the use of iMRI were included in the study. The types of studies eligible for inclusion were observational case-control and cohort studies, randomized clinical trials, cross-sectional studies, editorials, case series, and commentaries. Articles were de-duplicated and abstracts independently screened for inclusion by two reviewers. Full texts were screened, and data on demographic characteristics, etiology, outcome (extent of resection for neuro-oncology and Engel class for epilepsy), and technical iMRI data were extracted. RESULTS: Thirty-five articles were included in the review, 25 of which were observational cohort studies. Four articles were suitable for meta-analysis. In total, 1217 patients underwent iMRI-guided neuro-oncology surgery in 26 studies, most commonly for gliomas (n = 443). A total of 148 patients underwent iMRI-guided epilepsy surgery in 9 studies, with focal cortical dysplasia being the most common diagnosis (n = 95). The mean ± SD operating time was 357 ± 94 minutes (12 studies), with a mean of 1.32 scans per patient. There was a mean re-entry rate into the operative field of 42% (across 20 studies). Complications were noted in 21% of epilepsy surgery patients and 11% of neuro-oncology surgery patients. Meta-analysis of 4 eligible studies revealed that iMRI was more likely to lead to better Engel outcomes in terms of seizure freedom (OR 3.84, 95% CI 1.38-10.68, p = 0.69) and complete tumor resection (OR 3.19, 95% CI 0.28-36.92, p = 0.06). CONCLUSIONS: iMRI appears to be a useful adjunct in optimizing resective pediatric epilepsy and neuro-oncology surgery, with a low complication rate.

What can a morphometric study of unoperated children teach us about the natural history of metopic synostosis?

OBJECTIVE: Outcomes of surgical repair of trigonocephaly are well reported in the literature, but there is a paucity of information on the natural history of unoperated children. The authors evaluated a group of unoperated children with metopic synostosis to describe the natural change in head shape over time. METHODS: A database was screened for scans of children with unoperated trigonocephaly (2010-2021). Multisuture cases and those with a metopic ridge were excluded. Three-dimensional surface scans (3D stereophotogrammetry/CT) were used for morphological analysis. Nine previously published parameters were used: frontal angle (FA30°), anteroposterior (AP) volume ratio (APVR), AP area ratio (APAR), AP width ratios 1 and 2 (APWR1 and APWR2), and 4 AP diagonal ratios (30° right APDR [rAPDR30], 30° left APDR [lAPDR30], 60° right APDR [rAPDR60], and 60° left APDR [lAPDR60]). RESULTS: Ninety-seven scans were identified from a cohort of 316 patients with a single metopic suture, in which the male-to-female ratio was 2.7:1. Ages at the time of the scan ranged from 9 days to 11 years and were stratified into 4 groups: group 1, < 6 months; group 2, 6-12 months; group 3, 1-3 years; and group 4, > 3 years. Significant improvements were detected in 5 parameters (APVR, APAR, APWR1, rAPDR30, and lAPDR30) over time, whereas no significant differences were found in FA30, APWR2, rAPDR60, and lAPDR60 between age groups. CONCLUSIONS: Forehead shape (surface area and volume), as well as narrowing and anterolateral contour at the frontal points, differed significantly over time without surgery. However, forehead angulation, narrowing, and anterolateral contour at temporal points did not show significant differences. This knowledge will aid in surgical and parental decision-making.

Optic Nerve Head Morphological Variation in Craniosynostosis: A Cohort Study.

OBJECTIVE: To evaluate optic nerve head (ONH) morphology in children with craniosynostosis versus healthy controls. DESIGN: Single-center, prospective cohort study. METHODS: Handheld optical coherence tomography (OCT) was performed in 110 eyes of 58 children (aged 0-13 years) with craniosynostosis. Inclusion criteria were as follows: normal intracranial pressure on invasive overnight monitoring, or clinically stable intracranial pressure. The latter was defined as stable VA within 1 logMAR line and no papilledema on fundoscopy for at least 4 months following OCT, and normal/stable visual evoked potentials. Control data for 218 eyes of 218 children were obtained from a published normative dataset. The main outcome measures were disc width, cup width, rim width, and retinal nerve layer thickness (nasal and temporal). Outcome measures were compared using three-way linear mixed model regression analysis (fibroblast growth factor receptor [FGFR] 1/2-associated craniosynostosis, non-FGFR 1/2-associated craniosynostosis, and controls). RESULTS: Out of 63 eligible children with craniosynostosis, handheld OCT imaging was successful in 110 eyes of 58 children (92%). Of these, 22 (38%) were female. Median subject age at OCT examination was 53 months (range: 2-157; IQR: 39-73). Twelve children (21%) had FGFR1/2-associated syndromes (Crouzon, n = 6; Apert, n = 4; Pfeiffer, n = 2). Control data were available for 218 eyes of 218 healthy children. 122 controls (56%) were female. Median control age at OCT examination was 20 months (range: 0-163; IQR: 6-59). When comparing ONH morphology in craniosynostosis (n = 58) versus controls (n = 218), disc width was 6% greater (P = .001), temporal cup width was 13% smaller (P = .027), rim width was 16% greater (P < .001) and temporal retinal nerve fiber layer was 11% smaller (P = .027). When comparing FGFR1/2-associated syndromes (Crouzon, Apert, and Pfeiffer syndromes, n = 12) to the rest of the craniosynostosis group (n = 46), disc width was 10% smaller (P = .014) and temporal cup width was 38% smaller (P = .044). CONCLUSIONS: This cohort demonstrated morphological differences of the ONH in craniosynostosis, most markedly in Crouzon, Apert, and Pfeiffer syndromes. These findings could help improve ophthalmological monitoring and surgical decision-making in children with craniosynostosis. Further work on longitudinal ONH changes in syndromic and nonsyndromic craniosynostosis would be valuable.

Using A Disentangled Neural Network to Objectively Assess the Outcomes of Midfacial Surgery in Syndromic Craniosynostosis.

BACKGROUND: Advancements in artificial intelligence and the development of shape models that quantify normal head shape and facial morphology provide frameworks by which the outcomes of craniofacial surgery can be compared. In this work, we will demonstrate the use of the Swap Disentangled Variational Autoencoder (SD-VAE) to objectively assess changes following midfacial surgery. MATERIALS AND METHODS: Our model is trained on a dataset of 1405 3D meshes of healthy and syndromic patients which was augmented using a technique based on spectral interpolation. Patients with a diagnosis of Apert and Crouzon syndrome who had undergone sub- or trans-cranial midfacial procedures utilising rigid external distraction were then interpreted using this model as the point of comparison. RESULTS: A total of 56 patients met our inclusion criteria, 20 with Apert and 36 with Crouzon syndrome. By using linear discriminant analysis to project the high-dimensional vectors derived by SD-VAE onto a 2D space, the shape properties of Apert and Crouzon syndrome can be visualised in relation to the healthy population. In this way, we are able to show how surgery elicits global shape changes in each patient. To assess the regional movements achieved during surgery, we use a novel metric derived from the Malahanobis distance to quantify movements through the latent space. CONCLUSION: Objective outcome evaluation, which encourages in-depth analysis and enhances decision making, is essential for the progression of surgical practice. We have demonstrated how artificial intelligence has the ability to improve our understanding of surgery and its effect on craniofacial morphology.

Spring-assisted posterior vault expansion: a parametric study to improve the intracranial volume increase prediction.

Spring-assisted posterior vault expansion has been adopted at the London Great Ormond Street Hospital for Children to treat raised intracranial pressure in patients affected by syndromic craniosynostosis, a congenital calvarial anomaly causing the premature fusion of skull sutures. This procedure involves elastic distractors used to dynamically reshape the skull and increase the intracranial volume (ICV). In this study, we developed and validated a patient-specific model able to predict the ICV increase and carried out a parametric study to investigate the effect of surgical parameters on that final volume. Pre- and post-operative computed tomography data relative to 18 patients were processed to extract simplified patient-specific skull shape, replicate surgical cuts, and simulate spring expansion. A parametric study was performed to quantify each parameter's impact on the surgical outcome: for each patient, the osteotomy location was varied in a pre-defined range; local sensitivity of the predicted ICV to each parameter was analysed and compared. Results showed that the finite element model performed well in terms of post-operative ICV prediction and allowed for parametric optimization of surgical cuts. The study indicates how to optimize the ICV increase according to the type of procedure and provides indication on the most robust surgical strategy.

Sagittal synostosis: does choice of intervention and its timing affect the long-term aesthetic and neurodevelopmental outcome? A single-institution study of 167 children.

OBJECTIVE: Sagittal craniosynostosis (SC) is the most commonly encountered form of craniosynostosis. Despite its relative frequency, there remains significant heterogeneity in both operative management and follow-up between centers and a relative paucity of long-term outcome data in the literature. At the authors' institution, families of children presenting with SC are offered the following options: 1) conservative management with ophthalmic surveillance, 2) minimally invasive surgery at < 6 months of age (spring-assisted cranioplasty [SAC]) or 3) calvarial vault remodeling at any age (CVR). The authors reviewed outcomes for all children presenting with SC during a 5-year period, regardless of the treatment received. METHODS: Consecutive children born between January 1, 2008, and December 31, 2012, presenting with SC were identified, and detailed chart reviews were undertaken. Demographic, surgical, perioperative, head shape, scar, and neurodevelopmental (behavioral, education, speech, and language) data were analyzed. The cohort was divided by type of surgery (none, SAC, or CVR) and by age at surgery (early, defined as ≤ 6 months; or late, defined as > 6 months) for comparison purposes. RESULTS: A total of 167 children were identified, 129 boys and 38 girls, with a median age at presentation of 5.0 (range 0.4-135) months. Three families opted for conservative management. Of the 164 children who underwent surgery, 83 underwent SAC, 76 underwent CVR, and 5 underwent a "hybrid" procedure (CVR with springs). At a median age of 7.0 (range 0.5-12.3) years, there was no significant difference in concerns regarding head shape, scar, or neurodevelopmental outcomes between the early and late intervention groups over all procedures performed, or between the early or late SAC and CVR cohorts. There were more head shape concerns in the SAC group than in the CVR group overall (25.7% vs 11.8%, respectively; p = 0.026), although most of these concerns were minor and did not require revision. CONCLUSIONS: In this cohort, regardless of operative intervention and timing of intervention, infants achieved similar neurodevelopmental outcomes. Minimally invasive surgery (SAC) appears to result in less complete correction of head shape than CVR, but this may be balanced by advantages in reduced operative time, hospitalization, and blood loss. SAC was equal to CVR in neuropsychological outcomes.

Comparison of Internal and External Distraction in Frontofacial Monobloc Advancement: A Three-Dimensional Quantification.

BACKGROUND: Crouzon syndrome is characterized by complex craniosynostosis and midfacial hypoplasia. Where frontofacial monobloc advancement (FFMBA) is indicated, the method of distraction used to achieve advancement holds an element of equipoise. This two-center retrospective cohort study quantifies the movements produced by internal or external distraction methods used for FFMBA. Using shape analysis, this study evaluates whether the different distraction forces cause plastic deformity of the frontofacial segment, producing distinct morphologic outcomes. METHODS: Patients with Crouzon syndrome who underwent FFMBA with internal distraction [Hôpital Necker-Enfants Malades (Paris, France)] or external distraction [Great Ormond Street Hospital for Children (London, United Kingdom)] were compared. Digital Imaging and Communications in Medicine files of preoperative and postoperative computed tomographic scans were converted to three-dimensional bone meshes and skeletal movements were assessed using nonrigid iterative closest point registration. Displacements were visualized using color maps and statistical analysis of the vectors was undertaken. RESULTS: Fifty-one patients met the strict inclusion criteria. Twenty-five underwent FFMBA with external distraction and 26 with internal distraction. External distraction provides a preferential midfacial advancement, whereas internal distractors produce a more positive movement at the lateral orbital rim. This confers good orbital protection but does not advance the central midface to the same extent. Vector analysis confirmed this to be statistically significant ( P < 0.01). CONCLUSIONS: Morphologic changes resulting from monobloc surgery differ depending on the distraction technique used. Although the relative merits of internal and external distraction still stand, it may be that external distraction is more suited to addressing the midfacial biconcavity seen in syndromic craniosynostosis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Intracranial invasive group A streptococcus: a neurosurgical emergency in children.

OBJECTIVE: Invasive group A streptococcus (iGAS) infections are associated with a high rate of morbidity and mortality. CNS involvement is rare, with iGAS accounting for only 0.2%-1% of all childhood bacterial meningitis. In 2022, a significant increase in scarlet fever and iGAS was reported globally with a displacement of serotype, causing a predominance of the emm1.0 subtype. Here, the authors report on iGAS-related suppurative intracranial complications requiring neurosurgical intervention and prolonged antibiotic therapy. METHODS: The authors performed a retrospective chart review of consecutive cases of confirmed GAS in pediatric neurosurgical patients. RESULTS: Five children with a median age of 9 years were treated for intracranial complications of GAS infection over a 2-month period between November 2022 and December 2022. All patients had preceding illnesses, including chicken pox and upper respiratory tract infections. Infections included subdural empyema with associated encephalitis (n = 2), extradural empyema (n = 1), intracranial abscess (n = 1), and diffuse global meningoencephalitis (n = 1). Streptococcus pyogenes was cultured from 4 children, and 2 were of the emm1.0 subtype. Antimicrobial therapy in all patients included a third-generation cephalosporin but varied in adjunctive therapy, often including a toxin synthesis inhibitor antibiotic such as clindamycin. Neurological outcomes varied; 3 patients returned to near neurological baseline, 1 had significant residual neurological deficits, and 1 patient died. CONCLUSIONS: Despite the worldwide increased incidence, intracranial complications remain rarely reported resulting in a lack of awareness of iGAS-related intracranial disease. Awareness of intracranial complications of iGAS and prompt referral to a pediatric neurology/neurosurgical center is crucial to optimize neurological outcomes.

Electrophysiological and fundoscopic detection of intracranial hypertension in craniosynostosis.

AIMS: To assess the diagnostic accuracy of fundoscopy and visual evoked potentials (VEPs) in detecting intracranial hypertension (IH) in patients with craniosynostosis undergoing spring-assisted posterior vault expansion (sPVE). METHODS: Children with craniosynostosis undergoing sPVE and 48-hour intracranial pressure (ICP) monitoring were included in this single-centre, retrospective, diagnostic accuracy study. Data for ICP, fundoscopy and VEPs were analysed. Primary outcome measures were papilloedema on fundoscopy, VEP assessments and IH, defined as mean ICP > 20 mmHg. Diagnostic indices were calculated for fundoscopy and VEPs against IH. Secondary outcome measures included final visual outcomes. RESULTS: Fundoscopic examinations were available for 35 children and isolated VEPs for 30 children, 22 of whom had at least three serial VEPs. Sensitivity was 32.1% for fundoscopy (95% confidence intervals [CI]: 15.9-52.4) and 58.3% for isolated VEPs (95% CI 36.6-77.9). Specificity for IH was 100% for fundoscopy (95% CI: 59.0-100) and 83.3% for isolated VEPs (95% CI: 35.9-99.6). Where longitudinal deterioration was suspected from some prVEPs but not corroborated by all, sensitivity increased to 70.6% (95% CI: 44.0-89.7), while specificity decreased to 60% (95% CI: 14.7-94.7). Where longitudinal deterioration was clinically significant, sensitivity decreased to 47.1% (23.0-72.2) and specificity increased to 100% (47.8-100). Median final BCVA was 0.24 logMAR (n = 36). UK driving standard BCVA was achieved by 26 patients (72.2%), defined as ≥0.30 logMAR in the better eye. CONCLUSION: Papilloedema present on fundoscopy reliably indicated IH, but its absence did not exclude IH. VEP testing boosted sensitivity at the expense of specificity, depending on method of analysis.

Recognition of intracranial hypertension using handheld optical coherence tomography in children (RIO Study): a diagnostic accuracy study protocol.

INTRODUCTION: Paediatric intracranial hypertension (IH) is a rare but serious condition that can pose deleterious effects on the brain and vision. Estimating intracranial pressure (ICP) in children is difficult. Gold standard direct ICP measurement is invasive and carries risk. It is impractical to routinely perform direct ICP measurements over time for all children at risk of IH. This study proposes to assess the diagnostic accuracy of handheld optical coherence tomography (OCT), a non-invasive ocular imaging method, to detect IH in children. METHODS AND ANALYSIS: This is a prospective study evaluating the diagnostic accuracy of handheld OCT for IH in at risk children. Inclusion criteria include clinical and/or genetic diagnosis of craniosynostosis, idiopathic intracranial hypertension, space occupying lesion or other conditions association with IH and age 0-18 years old. Exclusion criteria include patients older than 18 years of age and/or absence of condition placing the child at risk of IH. The primary outcome measures are handheld OCT and 48-hour ICP assessments, which will be used for diagnostic accuracy testing (sensitivity, specificity, positive predictive value, negative predictive value and accuracy). Main secondary outcome measures include visual acuity, fundoscopic examination, contrast sensitivity, visual field testing and visual evoked potentials, wherever possible. ETHICS AND DISSEMINATION: Ethical approval was granted for this study by the East Midlands Nottingham 2 Research Ethics committee (UOL0348/IRAS 105137). Our findings will be disseminated through presentation at relevant meetings, peer-reviewed publication and via the popular media. TRIAL REGISTRATION NUMBER: ISRCTN52858719.