Chiari malformation in craniosynostosis

Isolated Squamosal Synostosis: Defining the Phenotype

ABSTRACT

This study aims to characterize the clinical manifestations of isolated squamosal synostosis (ISS) and review the relevant published literature. Computed tomography imaging from 2008 to 2022 was reviewed to identify patients with ISS. Patients were reviewed for age at presentation, signs of intracranial pressure, and management. A systematic review was conducted of all studies on ISS from 1990 to 2023. Eighteen patients from our institution were included. Three unilateral cases were diagnosed at 1.4 ± 0.6 years. None had signs of intracranial hypertension nor required surgery. Of the 15 bilateral cases, 6 were completely fused and 9 were partially fused. Concern for intracranial hypertension was more frequent in patients with bilateral complete ISS (66%) than partial (22%). Vault remodeling was pursued in 5/6 patients with bilateral complete ISS and 4/9 patients with bilateral partial ISS. Systematic review yielded 13 cases of ISS. Four had unilateral ISS diagnosed at 5.2 ± 2.8 months. None had intracranial hypertension. Nine had bilateral ISS diagnosed at 31 ± 47.3 months. Three patients had signs of elevated intracranial pressure. ISS presentation seems to vary based on laterality. Unilateral ISS typically presents without intracranial hypertension. Bilateral ISS is often associated with intracranial hypertension, more so in cases of complete suture fusion. Bilateral ISS warrants close observation.

Maximizing the functional benefits of posterior calvarial vault distraction in syndromic craniosynostoses: a nuanced approach to volume, vein, vector, and the vexed challenge of functional outcome in craniosynostoses

PURPOSE

To evaluate indications, techniques, nuances, and outcomes of posterior cranial vault distraction (PCVD) in children with craniosynostoses.

METHODS

We performed clinical assessments, multidimensional CT, MRI brain rapid protocol, ophthalmological evaluation, sleep study, and nasal endoscopy (if indicated). Detailed data was collected in Excel. Customized craniotomy (supratorcular or subtorcular), distraction vectors, strategic barrel staving on stenosed bones (other than lambdoid), and ~ 2 cm relief craniectomy for venous decompression were employed. Additional procedures were performed for the frontal and midface aspects during distractor removal based on functional needs.

RESULTS

Thirty-seven patients (ages 4-204 months, mean 32.94 months) underwent PCVD. Supratorcular PCVD in 8, subtorcular in 29. The distraction vector was posterior-horizontal in 28 cases and posterior-inferior in 9. Strategic barrel staving was used in 8 cases, and venous decompression in 24. Initial assessments showed satisfactory clinical and radiological outcomes. Long-term follow-up indicated seven of 11 patients with hydrocephalus required a ventriculoperitoneal shunt, and two needed additional PCVD procedures due to symptom recurrence. Average intracranial volume increased by 186 ± 42.67 cm3 (18 patients), and the average distraction achieved was 21 ± 2.64 mm (37 patients). Additional procedures at the time of distractor removal included fronto-facial or monobloc advancement (n = 3), isolated fronto-orbital advancement and remodeling (n = 13), and midface distraction for airway issues (monobloc advancement, n = 3; isolated midface, n = 9). Nine patients underwent all three procedures in sequence.

CONCLUSION

PCVD is an accepted surgical strategy for craniosynostosis with posterior calvarial involvement. Our technical modifications aim to enhance functional and aesthetic outcomes without increasing morbidity.

Free-floating bone flap posterior cranial vault release in syndromic craniosynostosis

The aim of this study was to investigate the efficacy of non-detachable free-floating bone flap posterior cranial vault release (FFBF-PCVR) in syndromic craniosynostosis. A retrospective review was completed of subjects who underwent FFBF-PCVR at 4 time-points: within 3 months preoperatively, 7 days postoperatively, 3 months postoperatively and at the last follow-up postoperatively. Volumetric and craniometric data, the ratio of ventricular diameter, and the cerebellar tonsillar descent were measured after FFBF-PCVR by using computed tomographic and magnetic resonance imaging. A total of 19 patients underwent FFBF-PCVR. The mean age was 11.7 months (range 4-36 months). The mid cranial height, posterior cranial height, and anterior posterior diameter length significantly increased from preoperative to postoperative 7 days, from postoperative 7 days to postoperative3 months, and from postoperative 3 months to the last follow-up. There was a significant increase in pre- to 7 days postoperative intracranial volume (1195.21 ± 246.56 cm³, p < 0.001; respectively), 3 months postoperative intracranial volume (1228.03 ± 249.61 cm³, p < 0.001; respectively), and intracranial volume at last follow-up (1390.25 ± 219.99 cm³, p < 0.001; respectively). There was a significant increase in 7 days' postoperative to 3 months' postoperative intracranial volume (p < 0.001; respectively), and intracranial volume at last follow-up (p < 0.001; respectively). There was a significant increase in 3 months postoperative to intracranial volume at last follow-up (p < 0.001). The mean intracranial volume increased by an average of 36.6 percent (range, 18.1 to 79.2 percent) at last follow-up. The degree of hydrocephalus in the preoperative child was (45.77% ± 9.17%), and at the last follow-up after surgery, the degree of hydrocephalus was (35.02 ± 9.50%), p < 0.01). Preoperatively, 14 patients (73.7 percent) had radiographic evidence of Chiari malformation type I. The cerebellar tonsillar descent, measured using pre- and postoperative MRI, decreased in all patients after FFBF-PCVR (preoperative: 7.5 ± 1.4 mm, postoperative: 5.3 ± 1.7 mm; p = 0.001). FFBF-PCVR can efficiently expand the posterior cranial vault with only one surgical procedure. Moreover, it helps to relieve hydrocephalus and cerebellar tonsillar herniation.

CT-based and manual external skull measurements for Chiari-like malformation and syringomyelia in Pomeranians

Studies in Pomeranians as well as other breeds have looked at clinical signs or external features as predictors of Chiari-like malformation (CM) and syringomyelia (SM). The aim of this study is to describe and analyze morphometric factors of the skull of Pomeranians with and without CM/SM by means of CT as well as manual external measurements. Ninety-two Pomeranians >12 months of age were included that underwent both CT and MRI studies of the head and cervicothoracic vertebral column. Two observers independently reviewed the CT imaging studies and performed quantitative measurements. External measurements were taken from the head of dogs when under general anesthesia using a tape measure and a caliper. Externally measured mandible length was associated with the probability of having SM (p = 0.043). Mandible length was moderately correlated with weight (Pearson correlation coefficient = 0.585, p < 0.001). A cutoff for mandible length of 58 mm yielded a sensitivity of 96% (95% confidence interval 89-100%), meaning dogs in this study population with a mandible length shorter than 58 mm were highly likely to have SM. The measurement of the length of the mandible could help to determine the probability of a Pomeranian having SM, especially when combined with the presence or absence of owner reported clinicals signs as shown in previous studies.

Biobank for craniosynostosis and faciocraniosynostosis, rare pediatric congenital craniofacial disorders: a study protocol

PURPOSE

Craniosynostosis (CRS) is a rare congenital cranial malformation in which 1 or more cranial or facial sutures are fused in utero or rapidly fused in early infancy. The cranial sutures separate the skull bone plates and enable rapid growth of the skull in the first 2 years of life, in which growth is largely dictated by growth of the brain. CRS is a rare disease that occurs in 1 in 2100 to 1 in 2500 births and may be either nonsyndromic (also referred to as isolated) or syndromic. In syndromic CRS, other birth defects are present next to the CRS. The distinction between nonsyndromic and syndromic manifestations is made on the basis of dysmorphologic evaluation and genetic evaluation. Owing to advances in genetic diagnostics, nonsyndromic patients are increasingly recognized as syndromic patients. CRS treatment is almost entirely surgical and is sometimes paired with postoperative helmet therapy for maintenance. Corrective procedures are complex, long, and associated with the risk of numerous complications, including heavy blood loss and its sequelae. Although surgery may restore a normal appearance, even in nonsyndromic patients, patients may experience persistent deficits in intellectual ability and cognitive function. The European Commission (EC) has prioritized rare diseases in recent horizon European research programs; indeed, collections or even individual samples may be extremely valuable for research.

METHODS AND RESULTS

Here, we present a study protocol in which the combined expertise of clinicians and researchers will be exploited to generate a biobank dedicated to CRS. The generation of the CRS biobank presented in this study will include the collection of different types of biological materials as well as advanced radiological images available to the scientific community.

CONCLUSION

The activation of a CRS biobank will provide an opportunity to improve translational research on CRS and to share its benefits with the scientific community and patients and their families.

Chiari malformation type I and craniosynostosis in adults: Retrospective analysis over a 10 year period in a tertiary care Centre

BACKGROUND

Chiari malformation type 1 (CM1) pathophysiology remains uncertain. One theory involves small posterior fossa volumes leading to tonsillar herniation. Craniosynostosis causes suture fusion, which can limit skull growth, and has been investigated in paediatric CM1 cohorts. We aimed to identify the prevalence of concurrent craniosynostosis in adult CM1 patients.

METHODS

Surgically managed CM1 patients were identified from a pre-existing Edinburgh neurosurgical centres database spanning 10 years. Patients aged 16 years of age or older had their case notes reviewed retrospectively. Cross sectional imaging identified and classified craniosynostosis, tonsillar herniation and the presence of hydrocephalus or syrinxes.

RESULTS

35 cases met inclusion criteria. Seven cases (20%) had craniosynostosis, all of which were sagittal synostosis. There was no significant association between the presence of craniosynostosis and the degree of tonsillar herniation, presence of hydrocephalus or syrinx formation.

CONCLUSION

This is the first study to evaluate the prevalence of craniosynostosis in a cohort of surgically managed adult CM1 patients. Future studies should potentially investigate whether conservatively managed adult CM1 patients have similar rates of craniosynostosis and also lack significant associations to known CM1-related complications.

The Genetics of Chiari 1 Malformation

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2-3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years.

Changes in Ventricular Volume After Posterior Vault Distraction Osteogenesis in Patients With Syndromic and Nonsyndromic Craniosynostosis

OBJECTIVE

Little is known about the response of the ventricular system to cranial vault surgery in patients with craniosynostosis. This study aims to evaluate the changes in the cerebral ventricular system in response to posterior vault distraction osteogenesis (PVDO) in patients with syndromic and nonsyndromic craniosynostosis.

METHODS

A single-institution retrospective review of all patients with craniosynostosis undergoing PVDO from 2000 to 2022 was completed. Patients were included for analysis if they had pre and postoperative cranial computed tomography scans. Ventricular volume (VV) and intracranial volume (ICV) were calculated using segmentation software.

RESULTS

Both patients with syndromic synostosis and nonsyndromic synostosis (NSS) experienced a significant increase in ICV after PVDO, but only patients with NSS experienced a significant VV change ( P = 0.004). After normalization by ICV, total, lateral, and third VV changes retained significance with percentage increases of 114%, 117%, and 89%, respectively ( P < 0.05 for all).

CONCLUSION

The differing results between cohorts reinforce the concept that the intracranial milieu is different between patients with syndromic synostosis and NSS. The results of the NSS cohort suggest that these patients may exist in a compensated state in which a reduction in cerebral blood flow and VV allows for the maintenance of parenchymal health to prevent the development of intracranial hypertension. Further studies may explore VV as a surrogate marker of ICP elevation, and the utility of cranial vault remodeling on nonsynostotic pathologies with cephalocranial disproportion.

Chiari I Deformity: Beyond 5 mm below the Foramen Magnum

Although originally described as a consecutive series of pathologic changes, Chiari syndrome represents a spectrum of disease divided into two subsets: development deformities of the paraxial mesoderm manifesting after birth (types 0-1.5) and true congenital malformations due to failure of neural tube closure present in utero (types 2-5). Heterogeneity among patients with a Chiari deformity and incomplete understanding of its pathophysiologic characteristics have led to inconsistency in radiologic reporting and difficulty in defining appropriate management strategies tailored to an individual patient's condition. The radiologist is tasked with going beyond the criteria for cerebellar tonsillar herniation to define an individual patient's disease state, determine candidacy for surgery, and assist in selecting the proper surgical approach. In addition, the radiologist must be able to identify conditions that result in cerebellar tonsillar herniation that are not related to Chiari deformity to avoid inappropriate surgery. Last, the radiologist must be able to interpret postoperative imaging examinations to assess for adequacy of treatment and complications. The authors summarize recent literature regarding the pathophysiologic basis of Chiari 1 and related deformities and detail the ideal morphologic and physiologic imaging assessment, focusing on Chiari 1 and related deformities (Chiari 0, 0.5, and 1.5). Also discussed are surgical techniques and "pearls" of postsurgical imaging, including complications that must be recognized. This review provides clarity to a commonly encountered but less understood condition to optimize outcomes for patients with Chiari 1 and related deformities. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Huisman in this issue.

Neuroimaging in Nonsyndromic Craniosynostosis: Key Concepts to Unlock Innovation

Craniosynostoses (CRS) are caused by the premature fusion of one or more cranial sutures, with isolated nonsyndromic CRS accounting for most of the clinical manifestations. Such premature suture fusion impacts both skull and brain morphology and involves regions far beyond the immediate area of fusion. The combined use of different neuroimaging tools allows for an accurate depiction of the most prominent clinical-radiological features in nonsyndromic CRS but can also contribute to a deeper investigation of more subtle alterations in the underlying nervous tissue organization that may impact normal brain development. This review paper aims to provide a comprehensive framework for a better understanding of the present and future potential applications of neuroimaging techniques for evaluating nonsyndromic CRS, highlighting strategies for optimizing their use in clinical practice and offering an overview of the most relevant technological advancements in terms of diagnostic performance, radiation exposure, and cost-effectiveness.

Exploring pathogenesis, prevalence, and genetic associations in Chiari malformation type 1: a contemporary perspective

Chiari malformation type 1 (CM 1) entails a structural defect in the cerebellum, involving the herniation of cerebellar tonsils toward the foramen magnum. The symptomatic or asymptomatic nature of CM 1 is contingent upon the condition of malformation in the spinal cord. This review presents an updated perspective on the prevalence of CM 1, its pathogenesis, genetic associations, and treatment. CM 1 exhibits a higher prevalence in adult females than males. Despite the incomplete understanding of the exact cause of CM 1, recent research suggests the involvement of both genetic and environmental factors in its development. One of the reasons for the occurrence of CM 1 in individuals is the smaller posterior cranial fossa, which manifests as typical morphological features. Additionally, environmental factors can potentially interact with genetic factors, modifying the observable characteristics of the disease and affecting the symptoms, severity, and development of the condition. Notably, headaches, neck pain, dizziness, and neurological deficits may be exhibited by individuals with CM 1, highlighting the importance of early diagnosis. Magnetic resonance imaging (MRI) serves as an alternative diagnostic technique for monitoring the symptoms of CM 1. Multiple genetic factors are likely to contribute to a cascade of abnormalities in CM 1. Early studies provided evidence, including clustering within families, bone development, and co-segregation with known genetic syndromes, establishing CM 1's association with a genetic basis. Furthermore, surgery is the only available treatment option to alleviate symptoms or hinder the progression of damage to the central nervous system (CNS) in CM 1 cases.

Are Chiari Malformation and Basilar Invagination Associated with Jugular Foramen Stenosis?

OBJECTIVE

We compared the diameter of the jugular foramen (JF) between normal individuals and those with a diagnosis of craniovertebral junction abnormalities, such as Chiari malformation type I (CMI) and/or basilar invagination (BI).

METHODS

This cross-sectional analytical study measured the diameter of the right and left JF on magnetic resonance imaging scans of patients divided into 4 groups: 68 with combined CMI and BI (CMI+BI), 42 with isolated BI, 45 with isolated CMI, and 102 control cases. The t test determined sex differences, and univariate analysis of variance with Tukey's post hoc test assessed JF differences between groups.

RESULTS

Considering all combinations of laterality and sex, the CMI+BI group had a JF narrower than their respective control groups. The JF was bilaterally narrower in the BI group than in the control group only in the women. Regardless of laterality, the CMI group had a wider JF than did the CMI+BI group in men and did not differ from that of the control group. In the female patients with CMI, the right JF did not differ from that of the controls and was wider than that in the CMI+BI group. Also, the left JF was narrower than that in the control group and did not differ from that in the CMI+BI group.

CONCLUSIONS

JF narrowing is associated with CMI and BI when combined in the same patient. When CMI or BI are detected separately, they do not imply evident changes in JF morphometry. It is expected that these findings could bring empiric substrate to support theories that claim a possible role of intracranial pressure disturbances as a triggering factor for CMI.

The Top 100 Most-Cited Publications in Clinical Craniofacial Research

INTRODUCTION

Craniosynostosis is a birth defect defined as premature closure of sutures leading to possible neurological deficits and cosmetic deformities. Most of the current literature to date focuses on craniosynostosis etiology by analyzing genetics. This paper is a bibliometric analysis of the most influential works related to the clinical management of craniosynostosis to help guide clinicians in their decision-making.

METHODS AND MATERIALS

Clarivate Web of Science database was used to identify the top 100 most-cited articles addressing the clinical management of craniosynostosis. A bibliometric review was performed to analyze publication metrics and track research trends.

RESULTS

The 100 most-cited publications pertaining to craniosynostosis management were cited a cumulative 12,779 times. The highest cited article was Shillito and colleagues' "Craniosynostosis: A Review Of 519 Surgical Patients" with 352 citations. The oldest clinical craniosynostosis article dates back to 1948, and the most recent was published in 2016. The year with the most clinical-focused publications was 2011. The most prolific author was Renier, D. The United States produced 56 of the 100 articles. Most articles (n=52) were level 3 evidence.

DISCUSSION

This bibliometric evaluation of craniosynostosis provides insight into the most impactful literature on this topic. The highest cited articles retrospectively analyze large sample sizes, outline proper evaluation, discuss intervention timelines, and highlight specific treatment plans for this birth defect. By filtering through existing literature, this analysis can guide clinicians on the management of craniosynostosis to maximize patient outcomes.

Preprocedural Electrophysiological Monitoring in Craniofacial Surgery for a Patient with Chiari Malformation

Head and neck positioning is a key element of craniofacial reconstructive surgery and can become challenging when intervention necessitates broad exposure of the calvarium. We present a case of craniosynostosis secondary to Apert's syndrome requiring anterior and posterior cranial vault access during surgical correction. A modified sphinx position was used that required significant neck extension. The patient had concurrent Chiari I malformation with brain stem compression so intraoperative neuromonitoring (IONM) was used to ensure that there were no negative effects on the neural elements with positioning. This highlights benefits of IONM in a setting not typically associated with its use.

Are Patients with Syndromic Craniosynostosis at Greater Risk for Epilepsy than Patients with Nonsyndromic Craniosynostosis?

OBJECTIVE

The aim of this study was to determine whether patients with syndromic craniosynostosis (SCS) are at increased risk for epilepsy relative to patients with nonsyndromic craniosynostosis (NSCS).

METHODS

A retrospective cohort study was completed using the Kids' Inpatient Database (KID). All patients diagnosed with craniosynostosis (CS) were included. The primary predictor variable was study grouping (SCS vs. NSCS). The primary outcome variable was a diagnosis of epilepsy. Descriptive statistics, univariate analyses and multivariate logistic regression were performed to identify independent risk factors for epilepsy.

RESULTS

The final study sample included a total of 10,089 patients (mean age, 1.78 years ± 3.70; 37.7% female). 9278 patients (92.0%) had NSCS, and the remaining 811 patients (8.0%) had SCS. A total of 577 patients (5.7%) had epilepsy. Not controlling for other variables, patients with SCS were at increased risk for epilepsy relative to patients with NSCS (OR 2.1, P < 0.001). After controlling for all significant variables, patients with SCS were no longer at increased risk for epilepsy relative to patients with NSCS (OR 0.73, P = 0.063). Hydrocephalus, Chiari malformation (CM), obstructive sleep apnea (OSA), atrial septal defect (ASD), gastro-esophageal reflux disease (GERD) were all independent risk factors (P < 0.05) for epilepsy.

CONCLUSIONS

Syndromic craniosynostosis (SCS) in itself is not a risk factor for epilepsy relative to NSCS. The greater prevalence of hydrocephalus, CM, OSA, ASD, and GERD, all of which were risk factors for epilepsy, in patients with SCS relative to patients with NSCS likely explains the greater prevalence of epilepsy in SCS relative to NSCS.

Re-imagining early cloverleaf skull deformity management from front to back approach-30 years on

The cloverleaf skull deformity remains among the most complicated craniofacial conditions to successfully manage. Many cases achieve largely unsatisfactory outcomes due to the requirement for frequent reoperation on the cranial vault and failure to deal with all the elements of the craniofaciostenosis in a timely fashion. Early cranial vault surgery without addressing the cranial base deformity and its attendant cerebrospinal fluid flow changes is invariably challenging and disappointing. A recent focus on the expansion of the posterior cranial vault as a primary procedure with the greater volume change allows a delay in fronto-orbital advancement and reduced need for repeat surgery. We herein describe three cases of complex multisuture craniosynostosis with cloverleaf skull deformity who underwent neonatal posterior cranial vault decompression along with foramen magnum decompression. Our report examines the safety and rationale for this pre-emptive surgical approach to simultaneously deal with the cranial vault and craniocervical junction abnormalities and thus change the early trajectory of these complex cases.

Human genetics and molecular genomics of Chiari malformation type 1

Chiari malformation type 1 (CM1) is the most common structural brain disorder involving the craniocervical junction, characterized by caudal displacement of the cerebellar tonsils below the foramen magnum into the spinal canal. Despite the heterogeneity of CM1, its poorly understood patho-etiology has led to a 'one-size-fits-all' surgical approach, with predictably high rates of morbidity and treatment failure. In this review we present multiplex CM1 families, associated Mendelian syndromes, and candidate genes from recent whole exome sequencing (WES) and other genetic studies that suggest a significant genetic contribution from inherited and de novo germline variants impacting transcription regulation, craniovertebral osteogenesis, and embryonic developmental signaling. We suggest that more extensive WES may identify clinically relevant, genetically defined CM1 subtypes distinguished by unique neuroradiographic and neurophysiological endophenotypes.

Decoding Chiari Malformation and Syringomyelia: From Epidemiology and Genetics to Advanced Diagnosis and Management Strategies

Chiari Malformation and Syringomyelia are neurosurgical entities that have been the subject of extensive research and clinical interest. Globally prevalent, these disorders vary demographically and have witnessed evolving temporal trends. Chiari Malformation impacts the normal cerebrospinal fluid flow, consequently affecting overall health. Key observations from canine studies offer pivotal insights into the pathogenesis of Syringomyelia and its extrapolation to human manifestations. Genetics plays a pivotal role; contemporary knowledge identifies specific genes, illuminating avenues for future exploration. Clinically, these disorders present distinct phenotypes. Diagnostically, while traditional methods have stood the test of time, innovative neurophysiological techniques are revolutionizing early detection and management. Neuroradiology, a cornerstone in diagnosis, follows defined criteria. Advanced imaging techniques are amplifying diagnostic precision. In therapeutic realms, surgery remains primary. For Chiari 1 Malformation, surgical outcomes vary based on the presence of Syringomyelia. Isolated Syringomyelia demands a unique surgical approach, the effectiveness of which is continually being optimized. Post-operative long-term prognosis and quality of life measures are crucial in assessing intervention success. In conclusion, this review amalgamates existing knowledge, paving the way for future research and enhanced clinical strategies in the management of Chiari Malformation and Syringomyelia.

Craniofacial Distraction Osteogenesis

Distraction osteogenesis (DO) of the craniofacial skeleton has become an effective technique for the treatment of both nonsyndromic and syndromic conditions. The advent of craniofacial DO has allowed for earlier intervention in pediatric patients with less complication risk and morbidity compared to traditional techniques. In this review, we will discuss current application and technique for craniofacial DO by anatomical region and explore future applications in craniofacial surgery.

Minor Suture Fusion is Associated With Chiari Malformation in Nonsyndromic Craniosynostosis

Here, we focused on the association between minor suture fusion and Chiari malformation (CM) occurrence in nonsyndromic craniosynostosis (NSC), and evaluated how the minor suture affects the posterior cranial fossa by measuring the posterior fossa deflection angle (PFA). In this retrospective study, the clinical records of 137 patients who underwent surgery for NSC at Aichi Children's Health and Medical Center between April 2010 and May 2022 were analyzed. Clinical data from Aichi Developmental Disability Center Central Hospital was collected for 23 patients as the external validation set. Among the 137 patients, 123 were diagnosed with NSC and the remaining 14 with syndromic craniosynostosis. Of the 123 NSC patients, 23 patients presented with CM. Multivariate analysis showed that occipito-mastoid fusion was the only significant risk factor for CM ( P =0.0218). Within the NSC group, CM patients had a significantly increased PFA (6.33±8.10 deg) compared with those without CM (2.76±3.29 deg, P =0.0487). Nonsyndromic craniosynostosis patients with occipito-mastoid suture fusion had a significantly increased PFA (6.50±7.60 deg) compared with those without occipito-mastoid fusion (2.60±3.23 deg, P =0.0164). In the validation cohort, occipito-mastoid suture fusion was validated as an independent risk factor for CM in univariate analysis. Minor suture fusion may cause CM associated with NSC. Chiari malformation could develop due to an increased PFA due to minor suture fusion, which causes growth disturbance in the affected side and compensatory dilation in the contralateral side within the posterior cranial fossa.

Chiari I malformation: management evolution and technical innovation

BACKGROUND AND DEFINITION

In recent years thanks to the growing use of radiological assessment, Chiari I malformation became one of the major diseases for a neurosurgeon to deal with. CIM can be classified according to the extent of cerebellar tonsil tip into the foramen magnum being a protrusion over five mm considered pathological. Such a disease is a heterogeneous condition with a multifactorial pathogenetic mechanism that can subdivided into a primary and secondary form. Regardless of the form, it seems that CIM is the result of an imbalance between the volume of the braincase and its content. Acquired CIMs are secondary to conditions causing intracranial hypertension or hypotension while the pathogenesis of primary forms is still controversial.

PATHOGENESIS AND TREATMENT

There are several theories in the literature but the most accepted one implies an overcrowding due to a small posterior cranial fossa. While asymptomatic CIM do not need treatment, symptomatic ones prompt for surgical management. Several techniques are proposed being the dilemma centered in the need for dural opening procedures and bony decompression ones.

CONCLUSION

Alongside the paper, the authors will address the novelty presented in the literature on management, diagnosis and pathogenesis in order to offer a better understanding of such a heterogeneous pathology.

A Critical Update of the Classification of Chiari and Chiari-like Malformations

Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management.

The Chiari Malformations: A Bibliometric Analysis of the 100 Most Cited Articles

OBJECTIVE

The Chiari malformations present heterogeneous entities, raising many questions regarding their natural history, pathophysiology, treatment options, and prognosis. Bibliometric analyses have emerged as a method to assess the impact of articles in current clinical practice.

METHODS

The most cited articles were identified via Scopus Library by using the keywords "Chiari," "Arnold-Chiari," and "Chiari malformation." The 100 most cited articles were then assembled and analyzed in detail.

RESULTS

The top 100 articles yielded a mean of 155,28 citations per article, ranging from 87 to 896 citations, and from 1.63 to 38.96 per year. Years of publications ranged from 1950 to 2015. Oakes was the most cited author (n = 7), followed by Tubbs and Milhorat. The country with the highest cited articles was the United States (n = 63), followed by the United Kingdom (n = 6), Italy (n = 5), Spain (n = 5), Japan (n = 4), and Germany (n = 3). Neurosurgery is the journal with the most highly cited articles (n = 21), followed by Journal of Neurosurgery (n = 19). Most articles focused on Chiari malformation type I (n = 83). The topic discussed most often was imaging (n = 63), followed by the evaluation of treatment outcome (n = 58), clinical signs and symptoms (n = 57), and the role of surgery (n = 56).

CONCLUSIONS

The present bibliometric analysis provides a succinct appraisal of the most cited articles concerning Chiari malformation, allowing a deeper insight in this area and its main influential articles with their impact on current clinical practice and future research.

Surgical outcomes of calvaria reconstruction in cranial pansynostosis associated with Arnold-Chiari type 1.5 malformation, a case report

A 6-year-old girl with persistent headaches and the visual problem was diagnosed as a delayed onset cranial pansynostosis with concurrent type 1.5 Arnold-Chiari malformation. She underwent multi-sutural reconstructive surgery and followed. The headache was greatly decreased and tonsillar-brain stem herniation and syrinx were resolved.

A diffusion tensor imaging analysis of white matter microstructures in non-operated craniosynostosis patients

PURPOSE

In 7 to 15-year-old operated syndromic craniosynostosis patients, we have shown the presence of microstructural anomalies in brain white matter by using DTI. To learn more about the cause of these anomalies, the aim of the study is to determine diffusivity values in white matter tracts in non-operated syndromic craniosynostosis patients aged 0-2 years compared to healthy controls.

METHODS

DTI datasets of 51 non-operated patients with syndromic craniosynostosis with a median [IQR] age of 0.40 [0.25] years were compared with 17 control subjects with a median of 1.20 [0.85] years. Major white matter tract pathways were reconstructed with ExploreDTI from MRI brain datasets acquired on a 1.5 T MRI system. Eigenvalues of these tract data were examined, with subsequent assessment of the affected tracts. Having syndromic craniosynostosis (versus control), gender, age, frontal occipital horn ratio (FOHR), and tract volume were treated as independent variables.

RESULTS

ʎ₂ and ʎ₃ of the tracts genu of the corpus callosum and the hippocampal segment of the cingulum bundle show a ƞ² > 0.14 in the comparison of patients vs controls, which indicates a large effect on radial diffusivity. Subsequent linear regressions on radial diffusivity of these tracts show that age and FOHR are significantly associated interacting factors on radial diffusivity (p < 0.025).

CONCLUSION

Syndromic craniosynostosis shows not to be a significant factor influencing the major white matter tracts. Enlargement of the ventricles show to be a significant factor on radial diffusivity in the tracts corpus callosum genu and the hippocampal segment of the cingulate bundle.

CLINICAL TRIAL REGISTRATION

MEC-2014-461.

The Course and Interaction of Ventriculomegaly and Cerebellar Tonsillar Herniation in Crouzon Syndrome over Time

Children with Crouzon syndrome have a higher incidence of cerebellar tonsillar herniation (TH) and ventriculomegaly than the general population, or children with other craniosynostosis syndromes.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

None.

2D and 3D cephalometric measurements.

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P < .05) and petrous-occipital (β = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P < .001) and occipitomastoid synchondrosis (β = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P < .001), anterior intraoccipital synchondrosis (β = -368.47; P < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Management of Lambdoid Craniosynostosis: A Comprehensive and Systematic Review

BACKGROUND

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

SUMMARY

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

Management of Chiari 1 malformation and hydrocephalus in syndromic craniosynostosis: A review

Chiari 1 malformation and hydrocephalus are frequent findings in multi-suture and syndromic craniosynostosis patients. In this article, we review the pathogenesis, clinical significance, and management options for these conditions with comments from our own experience. The role of premature fusion of skull base sutures leading to a crowded posterior fossa and venous outflow obstruction resulting in impaired cerebrospinal fluid (CSF) absorption is highlighted. Management options are unique in this group and we advocate early (prior to 6 months of age) posterior vault expansion by distraction osteogenesis (DO) in the management of Chiari 1 malformation. Foramen magnum decompression is recommended for a select few either as part of posterior vault expansion or at a later date. Treatment of hydrocephalus, utilizing a ventriculoperitoneal (VP) shunt with preferably a programmable high-pressure valve and anti-siphon device, is required in a small percentage of cases despite successful posterior vault expansion. Patients need to be carefully selected and managed as hydrocephalus often serves as an important cranial vault growth stimulus. Further, they require careful monitoring and thought to ensure the management of these conditions and the timing of any intervention provides the optimal long-term outcome for the patient.

Multisuture and syndromic craniosynostoses: Simplifying the complex

Most complex craniosynostoses are managed the same way as syndromic craniosynostoses (SCs), as these patients often experience similar problems regarding cognition and increased intracranial pressure (ICP). The evaluation and treatment plan for craniosynostoses is complex, and this, additionally, is complicated by the age at presentation. In this article, the authors review the complexity of SCs in the presentation and management. An algorithm is necessary for such multifaceted and multidimensional pathology as craniosynostoses. In most algorithms, posterior calvarial distraction is a consistent early option for complex craniosynostoses presenting early with raised ICP. Addressing the airway early is critical when significant airway issues are there. All other surgical interventions are tailored on the basis of presentation and age.

Association between Brachycephaly, Chiari Malformation, and Basilar Invagination

BACKGROUND

 There is evidence that Chiari malformation (CM) and basilar invagination (BI) are largely due to disproportion between the content and volume of the posterior fossa. A recent study identified an increased association between brachycephaly and BI. In several types of craniosynostosis, the posterior fossa volume is smaller than normal, and this is more pronounced in coronal synostosis. The aim of this study is to evaluate the association between CM and BI.

METHODS

 The cephalic index (CI) measured on magnetic resonance imaging (MRI) from a sample of patients with craniocervical malformation was compared with that of normal subjects.

RESULTS

 The average CI in the craniovertebral junction malformation (CVJM) group was significantly higher in BI patients than in normal subjects. The BI patients also had the highest CI among the whole sample of patients (p = 0.009).

CONCLUSIONS

 In this study, BI patients had the highest CI among patients with CVJM and a significantly higher CI than those in the control group. Our data confirm the association between BI and brachycephaly.

Complete posterior cranial vault distraction osteogenesis to correct Chiari malformation type I associated with craniosynostosis

OBJECTIVE

Posterior vault distraction osteogenesis (PVDO) is an effective tool to increase intracranial volume and expand the posterior cranial fossa. During PVDO, the authors extended osteotomy posterior to the foramen magnum to fully expand the posterior cranial fossa. The aim of this study was to investigate the efficacy of complete PVDO in posterior fossa expansion and treatment of Chiari malformation type I (CM-I) in patients with craniosynostosis.

METHODS

Patients with craniosynostosis who had undergone complete PVDO between January 2012 and May 2020 were reviewed retrospectively. A coronal osteotomy extending to the foramen magnum was performed and the foramen magnum was decompressed by removing its posterior rim with a 1-mm Kerrison rongeur. Four distractor devices were placed and the vector of distraction was controlled from the posterior to the inferior-posterior direction, depending on the deformity. Changes in the intracranial volume, posterior cranial fossa area, and cerebellar tonsillar descent were measured after complete PVDO by using CT and MRI.

RESULTS

A total of 11 patients with craniosynostosis and concurrent CM-I were included in the study. The mean age was 34.6 ± 24.0 months (continuous variables are expressed as the mean ± SD throughout). One patient had sleep apnea, which was consistent with CM-I, and another patient had a headache, which was nonspecific. The intracranial volume increased from 1179.6 ± 180.2 cm3 to 1440.6 ± 251.5 cm3 (p = 0.003; 24.5% increase compared to the preoperative volume). The posterior skull base area increased from 44.9 ± 19.3 cm2 to 72.7 ± 18.1 cm2 (p = 0.004). Cerebellar tonsillar descent decreased in all 11 patients after complete PVDO (preoperative: 10.8 ± 3.7 mm, postoperative: 2.7 ± 3.0 mm; p = 0.003). Among the 11 patients, 5 showed complete resolution of cerebellar tonsillar herniation.

CONCLUSIONS

Complete PVDO can more efficiently expand the posterior cranial fossa, unlike conventional methods. Moreover, it helps to relieve cerebellar tonsillar herniation. Complete PVDO is a powerful tool to increase the intracranial and posterior fossa volumes in patients with craniosynostosis and concurrent CM-I.

Neonatal hydrocephalus: an atypical presentation of malignant infantile osteopetrosis

PURPOSE

Autosomal recessive osteopetrosis has a variable presentation, most commonly including failure to thrive, hypocalcemia, seizures, hepatosplenomegaly, hydrocephalus, vision or hearing loss, and cytopenias. Multiple symptoms are usually seen at presentation. The variability of presentation often delays diagnosis and subsequent treatment. Here, we present a case of an infant with this condition who initially presented with triventricular hydrocephalus with Chiari I malformation. This alone is not a common presentation of this disease, and we present this case to highlight autosomal recessive osteopetrosis as a potential diagnosis in infants presenting with hydrocephalus and discuss the other associated symptoms, management, and prognosis of this condition.

CASE REPORT

The patient was a full-term infant with a routine newborn period. At 6 months, the infant had macrocephaly and frontal bossing with a bulging fontanelle. She was found to have hydrocephalus with moderate ventriculomegaly involving the third and lateral ventricles with an associated Chiari 1 malformation. The infant was asymptomatic at the time. The infant was promptly referred to neurosurgery and underwent an uncomplicated ventriculoperitoneal shunt placement. Post-operative X-rays showed increased density of the skull with other bone changes suggestive of autosomal recessive osteopetrosis. Subsequent lab work and imaging studies were consistent with this condition. The diagnosis was confirmed by genetic testing, and the patient has undergone treatment with hematopoietic stem cell transplant.

CONCLUSION

Hydrocephalus is a common feature of this condition, typically seen in conjunction with other systemic symptoms and laboratory findings. Our patient had a limited initial presentation of triventricular hydrocephalus with Chiari I malformation and was otherwise clinically asymptomatic. There is limited literature of such a presentation, and we highlight this case to increase awareness, as timely diagnosis of these patients is critical for treatment and future outcomes.

Craniosynostosis and hydrocephalus: relevance and treatment modalities

INTRODUCTION

Hydrocephalus is variously associated to syndromic craniosynostosis (CS), while it is randomly encountered in monosutural CS. Pathogenesis is still debated and reliable criteria for the diagnosis of overt hydrocephalus are lacking. Additionally, optimal treatment is controversial since it should balance the need to relieve intracranial hypertension and the risk of recurrence favored by lowering intracranial pressure.

METHODS

A thorough review of the literature has been performed. Accordingly, pathogenic theories, diagnostic issues, and treatment options on hydrocephalus presenting in the context of CS are discussed.

RESULTS

The association of hydrocephalus to simple CS is considered a fortuitous event. Its treatment is usually driven by the etiology and clinical relevance of hydrocephalus, favoring treatment before surgical correction to reduce CSF-related complications. On the other side, pathogenesis of hydrocephalus in the context of syndromic CS has been mainly related to factors that are secondary to the synostostic process, such as craniocerebral disproportion and venous hypertension. Hydrocephalus complicates 12-15% of syndromic CS, though its incidence is more relevant in FGFR2-related CS and raises up to 88% in Pfeiffer syndrome. Overt hydrocephalus should be properly differentiated by non-tense ventriculomegaly that is more frequent in Apert syndrome. Since intracranial hypertension is constant in syndromic CS even in the absence of active hydrocephalus, radiological monitoring of ventricular size along with intracranial pressure monitoring is essential. Active hydrocephalus occurs more frequently in infants, though stable ventriculomegaly may evolve into overt hydrocephalus after cranial expansion. If hydrocephalus is not clinically prominent, cranial expansion should be favored as first surgical step. Although posterior cranial expansion may address posterior cranial fossa constriction and stabilize ventricular dilation, effectiveness in long-term control of hydrocephalus is not clear. ETV is an effective treatment option, though success rate is affected by the presence of brain malformations and patient age. Extrathecal CSF shunting should be used as last resource due to the increased risk of complications in this context.

CONCLUSIONS

The pathogenesis of hydrocephalus complicating syndromic CS should be further investigated. Concomitantly, the definition of reliable diagnostic criteria is advocated in order to promptly and properly identify active hydrocephalus. Finally, treatment algorithm should refine the best timing and treatment options aiming to relieve intracranial hypertension on one side and reduce the risk of restenosis on the other side.

Does the association between abnormal anatomy of the skull base and cerebellar tonsillar position also exist in syndromic craniosynostosis?

PURPOSE

Cerebellar tonsillar herniation (TH) occurs frequently in syndromic craniosynostosis; however, the exact pathogenesis is unknown. This study evaluates the association between skull base deformities and TH in syndromic craniosynostosis.

METHODS

Retrospective study MRI study comparing syndromic craniosynostosis to controls. Measured parameters included clivus length, skull base angle, Boogard's angle, foramen magnum area, and cerebellar tonsillar position (TP). The association between skull base parameters and TP was evaluated with linear mixed models, correcting for age and risk factors for TH in craniosynostosis (hydrocephalus, intracranial hypertension, craniocerebral disproportion, and lambdoid synostosis).

RESULTS

Two hundred and eighty-two scans in 145 patients were included, and 146 scans in 146 controls. The clivus was smaller at birth, and its growth was retarded in all syndromes. The skull base angle was smaller at birth in Apert and Crouzon syndromes, and the evolution through time was normal. Boogard's angle was smaller at birth in Apert syndrome, and its evolution was disturbed in Apert and Saethre-Chotzen syndromes. The foramen magnum was smaller at birth in Crouzon and Saethre-Chotzen syndromes, and its growth was disturbed in Apert, Crouzon, and Saethre-Chotzen syndromes. TP was higher at birth in Apert syndrome, but lowered faster. In Crouzon syndrome, TP was lower at birth and throughout life. A smaller clivus and larger foramen magnum were associated with a lower TP in controls (p<0.001, p=0.007), and in Crouzon syndrome, this applied to only foramen magnum size (p=0.004).

CONCLUSION

The skull base and its growth are significantly different in syndromic craniosynostosis compared to controls. However, only foramen magnum area is associated with TP in Crouzon syndrome.

Clinical signs, interventions, and treatment course of three different treatment protocols in patients with Crouzon syndrome with acanthosis nigricans

OBJECTIVE

Crouzon syndrome with acanthosis nigricans (CAN) is a rare and clinically complex subtype of Crouzon syndrome. At three craniofacial centers, this multicenter study was undertaken to assess clinical signs in relation to the required interventions and treatment course in patients with CAN.

METHODS

A retrospective cohort study of CAN was performed to obtain information about the clinical treatment course of these patients. Three centers participated: Erasmus Medical Centre, Rotterdam, the Netherlands; John Radcliffe Hospital, Oxford, United Kingdom; and Hôpital Necker-Enfants Malades, Paris, France.

RESULTS

Nineteen patients (5 males, 14 females) were included in the study. All children were operated on, with a mean of 2.2 surgeries per patient (range 1-6). Overall, the following procedures were performed: 23 vault expansions, 10 monobloc corrections, 6 midface surgeries, 11 foramen magnum decompressions, 29 CSF-diverting surgeries, 23 shunt-related interventions, and 6 endoscopic third ventriculostomies, 3 of which subsequently required a shunt.

CONCLUSIONS

This study demonstrates that patients with the mutation c.1172C>A (p.Ala391Glu) in the FGFR3 gene have a severe disease trajectory, requiring multiple surgical procedures. The timing and order of interventions have changed among patients and centers. It was not possible to differentiate the effect of a more severe clinical presentation from the effect of treatment order on outcome.

Conventional posterior cranial vault expansion: indications and results-review of the literature

In the late 1980s, craniofacial surgery units reported suboptimal cosmetic results, cranial volume restriction, and intracranial hypertension after anterior cranial vault remodeling in bilateral coronal synostosis associated with severe brachyturricephaly. A possible explanation was a severe associated growth restriction of the posterior calvaria with radiological synostosis at the lambda sutures. "Conventional" or "fixed" posterior cranial vault expansion techniques were developed to address these limitations, sometimes as the first surgical step in a two-staged protocol of total calvarial reconstruction, combined with suboccipital decompression in cases of symptomatic cerebellar tonsillar herniation or, more easily, to resolve the characteristic occipital flattening of lambdoid synostosis. Various surgical approaches have been described; however, the indications for and timing of surgical treatment and postoperative evaluation of results still remain controversial. Although more invasive, conventional posterior cranial vault expansion has proven to be safe and offers a remodeled and protective bony vault immediately after surgery, but the underlying cranial base malformation remained untreated, with implications in the postoperative growth of the facial skeleton. Overcorrection, rigid stabilization, and grafting are also concerns to be addressed.

Posterior Cranial Vault Distraction Osteogenesis Utilizing a Posterior-Superior Distraction Vector in the Treatment of Mercedes Benz Pattern Craniosynostosis

ABSTRACT

Bilateral lambdoid and sagittal synostosis, or Mercedes Benz Syndrome, is a rare complex craniosynostosis resulting in frontal bossing, a tapered posterior fossa, and an anteriorly displaced cranial vertex. Its ideal surgical correction must result in posterior expansion, skull elongation, and caudal repositioning of the vertex. We present a craniometric analysis of skull changes with posterior-superior distraction and introduce a novel craniometric measure: vertex position. In this study, a retrospective review was performed to analyze outcomes of posterior cranial vault distraction osteogenesis (PVDO) using a posterior-superior distraction vector from 2016 to 2019. Cranial vertex position was measured as a fraction of the occipitofrontal diameter from rostral to caudal (0-1.0). Four patients underwent PVDO at mean age 10.61 ± 3.16 months utilizing a posterior-superior distraction vector. Linear distraction distance averaged 30.30 ± 0.90 mm with a mean consolidation period of 3.98 ± 0.72 months. Mean corrected change in intra-cranial volume was 236.30 ± 3.71 mL, at an average rate of 7.81 ± 2.00 mL/mm of distraction. Increases in anterior cranial height (7.83 ± 2.51 mm), middle cranial height (8.43 ± 4.21 mm), posterior cranial height (13.15 ± 7.45 mm), and posterior cranial fossa height (21.99 ± 8.55 mm) were observed. Cranial vertex demonstrated a mean posterior movement of 0.18 ± 0.13. PVDO utilizing a posterior-superior distraction vector for management of nonsyndromic bilateral lambdoid and sagittal synostosis effectively increases intracranial volume and height and provides an esthetic outcome with posterior movement of the cranial vertex.

Chiari I malformation and Noonan's syndrome: Shared manifestations of RASopathy

Neurologic sequalae of Noonan syndrome have been postulated in the literature. A topic of significance is the role of RASopathy in the shared pathophysiology of Noonan Syndrome and Chiari I malformation. In this unique case report, we present a patient with concomitant Noonan Syndrome and Chiari I with 4th ventricular outflow obstruction. The case highlights the importance of close clinical suspicion in this patient population. We utilize the case to delve into intricacies of the known pathophysiology and encourage ongoing investigation.

Pathogenesis and Classification of Chiari Malformation Type I Based on the Mechanism of Ptosis of the Brain Stem and Cerebellum: A Morphometric Study of the Posterior Cranial Fossa and Craniovertebral Junction

Introduction  We investigated the mechanism of ptosis of the brain stem and cerebellum (hindbrain) in Chiari malformation type I (CM-I) and classified CM-I according to pathogenesis, based on a morphometric study of the posterior cranial fossa (PCF) and craniovertebral junction (CVJ). We discuss the appropriate surgical treatment for hindbrain ptosis. Materials and Methods  We examined 500 patients with CM-I and 100 healthy control individuals. We calculated the volume of the PCF (VPCF) and measured the axial length of the enchondral parts of the occipital bone and hindbrain. As statistical analyses, for the multiple analyses, heavy palindromic tests were used. Using three independent objective parameters, we tried to classify CM-I. Results  Three independent subtypes were confirmed (CM-I types A, B, and C). CM-I type A (167 cases): normal VPCF, normal volume of the area surrounding the foramen magnum (VSFM), and normal occipital bone size; CM-I type B (178 cases): normal VPCF, small VSFM, and small occipital bone size; and CM-I type C (155 cases): small VPCF, small VSFM, and small occipital bone size. Conclusions  Morphometric analyses of PCF and CVJ were very useful for the investigation of the mechanism of hindbrain ptosis and classifying CM-I according to pathogenesis. CM-I type A included mechanisms other than hindbrain ptosis, for example, CVJ instability, tethered cord, and increased intracranial pressure. CM-I types B and C demonstrated underdevelopment of the occipital bone. For CM-I types B and C, posterior decompression should be performed. For CM-I type A, appropriate surgical management should be selected.

Surgical Management of Chiari Malformations: Preliminary Results of Surgery According to the Mechanisms of Ptosis of the Brain Stem and Cerebellum

Introduction  We classified Chiari malformation type I (CM-I) according to the mechanism of ptosis of the brain stem and cerebellum, based on a morphometric study of the posterior cranial fossa (PCF) and craniovertebral junction (CVJ). Surgery was performed to manage the mechanism of the hindbrain ptosis. Materials and Methods  We calculated the volume of the PCF (VPCF) and the area surrounding the foramen magnum (VSFM) and measured the axial length of the enchondral parts of the occipital bone (occipital bone size) and the hindbrain. According to these measures, we classified CM-I into type A (normal VPCF, normal VSFM, and normal occipital bone size), type B (normal VPCF, small VSFM, and small occipital bone size), and type C (small VPCF, small VSFM, and small occipital bone size). Foramen magnum decompression (FMD) (280 cases) was performed on CM-I types A and B. Expansive suboccipital cranioplasty (ESCP) was performed on CM-I type C. Posterior craniocervical fixation (CCF) was performed in cases with CVJ instability. Lysis of the adhesion and/or sectioning of the filum terminale were performed on cases with tethered cord syndrome. Results  Both ESCP and FMD had a high rate of improvement of neurological symptoms (87%) and recovery rate. There was only small number of complications. CCF had a high rate of improvement of neurological symptoms (88%) and joint stabilization. Conclusion  In the management of Chiari malformation, appropriate surgical methods that address ptosis of the hindbrain should be chosen. Each surgical approach resulted in a good improvement of neurological symptoms.

Chiari malformations in children: An overview

Chiari malformations encompass various radiological and clinical entities, sharing the herniation of the rhombencephalic structures through the foramen magnum as a common characteristic. They can be symptomatic or asymptomatic. The therapeutic strategies for these malformations differ on the basis of the diverse pathophysiologic processes that cause them. As Chiari malformations are caused by various pathophysiologic processes, they must be recognized promptly to select the best treatment for each single case.

Management of Pre-existing Ventriculoperitoneal Shunt in Posterior Vault Distraction for Lambdoid Craniosynostosis: A Case Report and Technical Note

Posterior vault distraction osteogenesis (DO) is an emerging treatment option for craniosynostosis. Operative nuances detailing surgical management are being described with increasing use and experience. In this article, we discuss the surgical management of an 8-month-old male with a ventriculoperitoneal shunt (VPS) diagnosed with bilateral lambdoid craniosynostosis and Chiari I malformation. The patient underwent successful bilateral posterior fossa DO without surgical re-implantation of the shunt. Pre- and post-operative imaging confirmed no migration of the VPS. Intracranial volume increased by 20.1% and posterior fossa volume increased by 39.9%. Our experience illustrates that posterior vault DO can be done safely in the setting of a parieto-occipital VPS, in a single operative setting, without the need of additional procedures.

Chiari Malformation Type 1 and Syringomyelia in a Patient With Prior Surgically-Treated Sagittal Synostosis Effectively Treated With Posterior Cranial Vault Distraction Osteogenesis

ABSTRACT

The presenting report describes the use of a posterior cranial vault distraction procedure in resolving a Chiari malformation with associated syringomyelia following a surgically-treated nonsyndromic craniosynostosis. Chiari malformations are typically treated with posterior fossa decompression with or without expansion duraplasty. The objective of this report is to describe the effectiveness in resolving both Chiari malformation and secondary syringomyelia with posterior cranial vault distraction osteogenesis. A 5-year-old male, with a history of surgery for sagittal synostosis during infancy, presented with daily severe headaches and dysesthesias in the hands and feet. Imaging demonstrated a copper-beaten calvarium and a Chiari 1 malformation with a 7 mm diameter C4-T1 syrinx. He underwent posterior cranial vault distraction osteogenesis over 3 months to increase his intracranial volume. The patients' headaches improved significantly, and his dysesthesias resolved postoperatively. A magnetic resonance imaging performed 7 months after completion of distraction demonstrated resolution of the Chiari malformation and decompression of his syrinx. A computed tomography scan at 9 months postdistraction showed resolution of the copper-beaten calvarium. Patients with a history of craniosynostosis can develop inadequate cranial volume over time due to abnormal skull growth, leading to secondary Chiari malformation with or without syringomyelia. Posterior vault distraction is an effective strategy to address these conditions and can be employed later in childhood to treat the underlying pathology. The mechanism potentially expands both calvarium and dura, which in turn addresses both the Chiari malformation and secondary syringomyelia.

Case Report: Pansynostosis, Chiari I Malformation and Syringomyelia in a Child With Frontometaphyseal Dysplasia 1

Frontometaphyseal dysplasia 1 (FMD1) is a rare otopalatodigital spectrum disorder (OPDSD) that is inherited as an X-linked trait and it is caused by gain-of-function mutations in the FLNA. It is characterized by generalized skeletal dysplasia, and craniofacial abnormalities including facial dysmorphism (supraorbital hyperostosis, hypertelorism, and down-slanting palpebral fissures). The involvement of the central nervous system in patients with OPDSD is rare. Herein, we present the case of a 12-year-old boy with facial dysmorphism, multiple joint contractures, sensorineural hearing loss, scoliosis, craniosynostosis, and irregular sclerosis with hyperostosis of the skull. Brain and whole-spine magnetic resonance imaging revealed Chiari I malformation with extensive hydrosyringomyelia from the C1 to T12 levels. Targeted next-generation sequencing identified a hemizygous pathologic variant (c.3557C>T/p.Ser1186Leu) in the FLNA, confirming the diagnosis of FMD1. This is the first report of a rare case of OPDSD with pansynostosis and Chiari I malformation accompanied by extensive syringomyelia.

Spring-assisted posterior vault expansion-a single-centre experience of 200 cases

PURPOSE

Children affected by premature fusion of the cranial sutures due to craniosynostosis can present with raised intracranial pressure and (turri)brachycephalic head shapes that require surgical treatment. Spring-assisted posterior vault expansion (SA-PVE) is the surgical technique of choice at Great Ormond Street Hospital for Children (GOSH), London, UK. This study aims to report the SA-PVE clinical experience of GOSH to date.

METHODS

A retrospective review was carried out including all SA-PVE cases performed at GOSH between 2008 and 2020. Demographic and clinical data were recorded including genetic diagnosis, craniofacial surgical history, surgical indication and assessment, age at time of surgery (spring insertion and removal), operative time, in-patient stay, blood transfusion requirements, additional/secondary (cranio)facial procedures, and complications.

RESULTS

Between 2008 and 2020, 200 SA-PVEs were undertaken in 184 patients (61% male). The study population consisted of patients affected by syndromic (65%) and non-syndromic disorders. Concerns regarding raised intracranial pressure were the surgical driver in 75% of the cases, with the remainder operated for shape correction. Median age for SA-PVE was 19 months (range, 2-131). Average operative time for first SA-PVE was 150 min and 87 for spring removal. Median in-patient stay was 3 nights, and 88 patients received a mean of 204.4 ml of blood transfusion at time of spring insertion. A single SA-PVE sufficed in 156 patients (85%) to date (26 springs still in situ at time of this analysis); 16 patients underwent repeat SA-PVE, whilst 12 underwent rigid redo. A second SA-PVE was needed in significantly more cases when the first SA-PVE was performed before age 1 year. Complications occurred in 26 patients with a total of 32 events, including one death. Forty-one patients underwent fronto-orbital remodelling at spring removal and 22 required additional cranio(maxillo)facial procedures.

CONCLUSIONS

Spring-assisted posterior vault expansion is a safe, efficient, and effective procedure based on our 12-year experience. Those that are treated early in life might require a repeat SA-PVE. Long-term follow-up is recommended as some would require additional craniomaxillofacial correction later in life.

Functional and morphological changes in hypoplasic posterior fossa

BACKGROUND

The knowledge of the development and the anatomy of the posterior cranial fossa (PCF) is crucial to define the occurrence and the prognosis of diseases where the surface and/or the volume of PCF is reduced, as several forms of craniosynostosis or Chiari type I malformation (CIM). To understand the functional and morphological changes resulting from such a hypoplasia is mandatory for their correct management. The purpose of this article is to review the pertinent literature to provide an update on this topic.

METHODS

The related and most recent literature addressing the issue of the changes in hypoplasic PCF has been reviewed with particular interest in the studies focusing on the PCF characteristics in craniosynostosis, CIM, and achondroplasia.

RESULTS AND CONCLUSIONS

In craniosynostoses, namely, the syndromic ones, PCF shows different degrees of hypoplasia, according to the different pattern and timing of early suture fusion. Several factors concur to PCF hypoplasia and contribute to the resulting problems (CIM, hydrocephalus), as the fusion of the major and minor sutures of the lambdoid arch, the involvement of the basal synchondroses, and the occlusion of the jugular foramina. The combination of these factors explains the variety of the clinical and radiological phenotypes. In primary CIM, the matter is complicated by the evidence that, in spite of impaired PCF 2D measurements and theories on the mesodermal defect, the PCF volumetry is often comparable to healthy subjects. CIM is revealed by the overcrowding of the foramen magnum that is the result of a cranio-cerebral disproportion (altered PCF brain volume/PCF total volume). Sometimes, this disproportion is evident and can be demonstrated (basilar invagination, real PCF hypoplasia); sometimes, it is not. Some recent genetic observations would suggest that CIM is the result of an excessive growth of the neural tissue rather than a reduced growth of PCF bones. Finally, in achondroplasia, both macrocephaly and reduced 2D and 3D values of PCF occur. Some aspects of this disease remain partially obscure, as the rare incidence of hydrocephalus and syringomyelia and the common occurrence of asymptomatic upper cervical spinal cord damage. On the other hand, the low rate of CIM could be explained on the basis of the reduced area of the foramen magnum, which would prevent the hindbrain herniation.

Posterior vault "free-floating" bone flap: indications, technique, advantages, and drawbacks

BACKGROUND

The enlargement of the posterior cranial fossa volume is considered one of the main steps of the surgical management of children with multiple sutures craniosynostosis. Different management options have been proposed including fixed expansive craniotomy, free bone flap craniotomy, and distraction osteogenesis.

OBJECTIVES

To review indications to "free bone flap" craniotomy for the posterior fossa expansion, detailing advantages, disadvantages, and complications related to the technique.

RESULTS AND CONCLUSIONS

A review of the literature shows that "free bone flap" posterior expansion cranioplasty still has a role, particularly in infants with thin and "honeycomb" structure of the bone, allowing to gain adequate intracranial volume increases and to postpone to a more adequate time surgery aimed at anterior cranial fossa expansion.