Cephalocranial Disproportion Research Articles

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

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. 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. 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). 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.

Oxycephaly-systematic review, case presentation, and diagnostic clarification.

Oxycephaly is a specific phenotype of multi-suture craniosynostosis that is often misrepresented. This study aims to review the relevant literature, clarify the diagnostic criteria, and present an alternate approach to its management. Published literature regarding oxycephaly was reviewed from 1997, when the largest series was published, until 2022. All cases at a single institution were then retrospectively reviewed. Over the last 25years, four studies met the inclusion criteria, none of which specifically defined oxycephaly. One case, in one study, was potentially consistent with the phenotype. An institutional review yielded two patients who met the original diagnostic criteria set forth by Renier and Marchac. Both patients had unexplained speech delays, mild retinal nerve fiber layer thickening, and diffuse inner table scalloping, along with the characteristic oxycephalic phenotype. One patient also had a direct intracranial pressure (ICP) measurement of 25mmHg, and the other had a Chiari I malformation. Both were treated with posterior vault distraction osteogenesis (PVDO) to alleviate the cephalo-cranial disproportion while simultaneously allowing for turricephaly correction. Oxycephaly presents with late onset multi-suture fusion. Patients have patent sutures at birth. Midface hypoplasia and known syndromic associations are absent. Patients demonstrate supraorbital recession, an obtuse fronto-nasal angle, and turricephaly without substantial brachycephaly. Over 60% of patients have symptomatic ICP elevation, the presentation of which ranges from headaches to rapidly progressive blindness. This rare form of craniosynostosis is particularly virulent and likely often missed due to diagnostic ambiguity and its relatively mild phenotype.

The Expanding Role of Posterior Vault Distraction Osteogenesis in Idiopathic Intracranial Hypertension and Slit Ventricle Syndrome.

The purpose of this study was to compare perioperative safety and efficacy of posterior vault distraction osteogenesis (PVDO) in patients with primary nonsynostotic cephalo-cranial disproportion, namely slit ventricle syndrome and idiopathic intracranial hypertension (IIH), to a cohort of patients with craniosynostosis (CS). A retrospective review of patients undergoing PVDO from 2009 to 2019 at our institution was performed. Craniosynostosis patients were matched by sex and age at PVDO to the nonsynostotic cohort. Operative details, perioperative outcomes, and distraction patterns were analyzed with appropriate statistics. Nine patients met inclusion criteria for the non-CS cohort. Six patients (67%) underwent PVDO for slit ventricle and the remaining 3 patients (33%) underwent PVDO for IIH. The majority of CS patients were syndromic (n = 6, 67%) and had multisuture synostosis (n = 7, 78%). The non-CS cohort underwent PVDO at a median 56.1 months old [Q1 41.1, Q3 86.6] versus the CS cohort at 55.7 months [Q1 39.6, Q3 76.0] (P = 0.931). Total hospital length of stay was longer in the non-CS patients (median days 5 [Q1 4, Q3 6] versus 3 [Q1 3, Q3 4], P = 0.021). Non-CS patients with ventriculoperitoneal shunts had significantly less shunt operations for ICP concerns post-PVDO (median rate: 1.74/year [Q1 1.30, Q3 3.00] versus median: 0.18/year [Q1 0.0, Q3 0.7]; P = 0.046). In this pilot study using PVDO to treat slit ventricle syndrome and IIH, safety appears similar to PVDO in the synostotic setting. The cohort lacks adequate follow-up to assess long term efficacy, although short-midterm follow-up demonstrates promising results with less need for shunt revision and symptomatic relief. Future studies are warranted to identify the preferred surgical approach in these complex patients.

Spring-assisted minimally invasive repair of sagittal craniosynostosis.

Craniosynostosis surgery is intended to repair cranial deformity, reduce the risk of increased intracranial pressure from cephalocranial disproportion, and reduce the risk of developmental delays. In recent years, minimally invasive surgical techniques have been developed to achieve these goals with less tissue disruption, lower rates of transfusion, and shorter recovery time. The operation focuses on unlocking the fused bones, while reshaping relies on an adjunct, most commonly a postoperative cranial molding helmet. As an alternative to the care-intensive helmeting process, reshaping with implanted cranial expander springs has emerged. In this video, the authors demonstrate their technique for spring-assisted minimally invasive repair of sagittal craniosynostosis.The video can be found here: https://vimeo.com/513923721

Hydrocephalus and Chiari malformation pathophysiology in FGFR2-related faciocraniosynostosis: A review

BackgroundPatients with syndromic faciocraniosynostosis due to the mutation of the fibroblast growth factor receptor (FGFR) 2 gene present premature fusion of the coronal sutures and of the cranial base synchondrosis. Cerebrospinal fluid (CSF) circulation disorders and cerebellar tonsil prolapse are frequent findings in faciocraniosynostosis. ObjectiveWe reviewed the medical literature on the pathophysiological mechanisms of CSF disorders such as hydrocephalus and of cerebellar tonsil prolapse in FGFR2-related faciocraniosynostosis. DiscussionDifferent pathophysiological theories have been proposed, but none elucidated all the symptoms present in Apert, Crouzon and Pfeiffer syndromes. The first theory that addressed CSF circulation disruption was the constrictive theory (cephalocranial disproportion): cerebellum and brain stem are constricted by the small volume of the posterior fossa. The second theory proposed venous hyperpressure due to jugular foramens stenosis. The most recent theory proposed a pressure differential between CSF in the posterior fossa and in the vertebral canal, due to foramen magnum stenosis.

A genotype-specific surgical approach for patients with Pfeiffer syndrome due to W290C pathogenic variant in FGFR2 is associated with improved developmental outcomes and reduced mortality

PurposeAmong children with FGFR2-associated Pfeiffer syndrome, those with the W290C pathogenic variant (PV) are reported to have the worst clinical outcomes. Mortality is high, and severe neurocognitive impairment has been reported in all surviving patients. However, it is unclear whether these poor outcomes are an unavoidable consequence of the PV itself, or could be improved with a genotype-specific treatment approach. The purpose of this report is to describe the more intensive surgical approach used for each of the three patients with W290C PV in FGFR2 at our center, all of whom survived and have normal neurocognitive functioning. MethodsRetrospective chart review. ResultsIn contrast to other patients with Pfeiffer syndrome at our center, all three patients who were subsequently found to have a W290C PV required a similar and more aggressive approach based on early cephalocranial disproportion. In contrast to previously reported W290C cases, each of our three patients survived and demonstrate normal neurocognitive functioning. ConclusionWhile previously reported outcomes in W290C-associated Pfeiffer syndrome have been extremely poor, we present three patients who underwent an intensive surgical approach and have normal development. This suggests that a personalized and aggressive surgical approach for children with W290C PV may dramatically improve clinical outcome.

Intracranial volume (ICV) in isolated sagittal craniosynostosis: a retrospective case-matched-control study.

Children with sagittal craniosynostosis (SC) are at risk of developing raised intracranial pressure (ICP). This is thought to result from cephalocranial disproportion-the restriction of normal cerebral development by a small cranial vault. It remains unclear whether intracranial volume (ICV) is altered in SC. This study offers a novel volumetric analysis of the scaphocephalic skull, comparing supratentorial (ST) volume, infratentorial (IT) volume, and total ICV of patients with sagittal synostosis to normal controls. ICVs of 32 consecutive patients undergoing total calvarial vault remodelling (TCVR) for isolated SC were compared to 32 age- and sex-matched normal controls. ICV was measured with manual techniques on head computerised tomographic (CT) scans using OsiriX software. A paired t test was used to compare data between cases and controls. Mean total ICV, ST volume and IT volume were larger in SC than in controls, except in females > 6months of age. There was no statistical significance. Regression analysis demonstrated larger ICVs in diseased children than in controls younger than 10months, at which age trend lines intersected and the reverse became true for older children. This likely represents an evolving risk of cephalocranial disproportion beyond 10months of age. The IT/ST volume ratio was conserved in scaphocephaly, and very closely approximated that of controls. Sagittal craniosynostosis appears to be associated with a larger cranial vault at less than 10months and a smaller vault at greater than 10months, although statistical significance was not achieved.

Computer Simulation and Optimization of Cranial Vault Distraction.

The objective of this study was to validate the proof of concept of a computer-simulated cranial distraction, demonstrating accurate shape and end volume. Detailed modeling was performed on pre- and postoperative computed tomographic (CT) scans to generate accurate measurements of intracranial volume. Additionally, digital distraction simulations were performed on the preoperative scan and the resultant intracranial volume and shape were evaluated. Tertiary Children's Hospital. Preoperative and postoperative CT images were used from 10 patients having undergone cranial distraction for cephalocranial disproportion. None; computer simulation. Computer simulation feasibility of cranial vault distraction was demonstrated through creation of digital osteotomies, simulating distraction through translating skull segments, followed by simulated consolidation. Accuracy of the model was evaluated through comparing the intracranial volumes of actual and simulated distracted skulls. The developed digital distraction simulation was performed on the CT images of 10 patients. Plotting the relationship between the actual and simulated postdistraction volumes for the 10 patients yielded a slope of 1.0 and a correlation coefficient of 0.99. The average actual resultant volume change from distraction was 77.0 mL, compared to a simulated volume change of 76.9 mL. Digital simulation of cranial distraction was demonstrated through manipulation of the CT images and confirmed by comparing the actual to simulated volume change. This process may provide objective data in designing an individual distraction plan to optimize volume expansion and resultant cranial shape as well as patient education.

Advantages of Calvarial Vault Distraction for the Late Treatment of Cephalocranial Disproportion.

Cephalocranial disproportion is a symptomatic condition related to a volume discrepancy between the calvarial vault and the brain. Traditional expansion techniques are unfavorable in older children due to inadequate dural ossification, lack of bone pliability, and limited future growth potential. The authors review their experience using distraction to close bone defects in this setting. A retrospective analysis was performed of all patients treated using distraction in this setting by a single surgeon. Demographic and outcomes data were collected. The efficacy of ossification of bone defects after expansion by distraction was measured using volume analysis of three-dimensional computed tomography (CT) scans. This required a CT scan at the completion of device activation and a follow-up CT scan 6 months or more beyond activation. Sixteen patients (17 distractions) met the imaging-based inclusion criteria. The average age at surgery was 3.97 (2.14-6.89) years. The mean initial bone defect volume after asymmetric transverse distraction was 7.26 (5.45-13.73) mL. The mean final defect volume was 2.18 (0.00-5.90) mL with a mean change of 5.08 (1.21-12.79) mL and mean interval time of 27.85 (7.13-56.39) months. This represents a mean percent defect closure of 72.30 (20.38-100.00). Distraction osteogenesis is a very effective tool for treating the older child with cephalocranial disproportion. The ability to ossify the bone defects without a donor site provides a considerable advantage in these patients.

Posterior cranial vault distraction osteogenesis: evolution of technique.

The rapid growth of the brain in the first few years of life drives the expansion of the cranial vault. This expansion occurs primarily at the cranial sutures; premature fusion of these results in growth restriction perpendicular to the axis of the suture. The result of this is physical deformation of the cranial and facial skeleton, as well as the distortion of the underling brain and its physiology. These patients can present with symptoms of raised intracranial pressure, neurodevelopmental delay, as well as the morphological features of craniosynostosis. Acquired conditions such as the slit ventricle syndrome may also result in cephalocranial disproportion with these clinical features. Traditional vault remodeling surgery is able to correct the physical abnormalities as well as correcting cephalocranial disproportion. Its limitations include the degree of scalp expansion achievable as well as resulting defects in the bone. The use of distraction osteogenesis of the cranial vault permits a controlled expansion in a predetermined vector in a gradual manner. When used in the calvarium, this combines the benefits of tissue expansion on the scalp, as well as stimulating the production of new bone, reducing the defects resulting from expansion. In this review, the authors describe some of the surgical considerations important to the use of this technique. This includes the relevant anatomy and technical aspects illustrated with the use of clinical cases. Finally, they present a summary of their experience and discuss the complications associated with cranial vault distraction osteogenesis.

Hypertensive slit ventricle syndrome: pseudotumor cerebri with a malfunctioning shunt?

Symptomatic shunt malfunction without ventricular enlargement is known as slit ventricle syndrome (SVS). Patients presenting with this syndrome are not a homogeneous group. Of the 5 different types classified by Rekate, Type 1 is caused by CSF overdrainage and is associated with low pressures; Types 2 and 3 are associated with shunt blockage and elevated CSF pressures; Type 4 is cephalocranial disproportion that increases brain parenchymal pressure but not CSF pressure; and Type 5 is headache unrelated to shunt function. The low and normal CSF pressure types are relatively well understood, but the high-pressure forms are more problematic. In the high-pressure forms of SVS it is said that the lack of ventricular dilation is related to a reduction in brain compliance analogous to idiopathic intracranial hypertension or pseudotumor cerebri. Despite this, there is little evidence in the literature to support this conjecture. With this in mind, 3 cases of SVS associated with elevated CSF pressure are presented. The MR venogram findings and hemodynamics of these 3 cases are shown to be identical to those of pseudotumor cerebri. A literature review indicates that an underlying venous impairment may be functioning in the patients who re-present with small ventricles following shunt malfunction.

Expanding Indications and Device Refinement in Posterior Cranial Vault Distraction Osteogenesis

Introduction: Expansion of the posterior cranial vault can be used to treat cephalocranial disproportion and cranial vault dysmorphology. Posterior cranial vault distraction osteogenesis has been described in syndromic patients with craniosynostosis as a viable method for expanding the posterior cranial vault, and has potential advantages over traditional expansion. The purpose of this study was to demonstrate the utility of posterior cranial vault distraction osteogenesis for treating a variety of craniosynostosis and cranial vault anomalies, as well as to review the development of a cranial-specific distraction device.

Volumetric Analysis of Cranial Vault Distraction for Cephalocranial Disproportion

The purpose of this study was to provide an objective analysis and quantify the intracranial volume change produced by cranial vault distraction osteogenesis. We recently published a technique to expand the cranial vault by distraction in symptomatic patients with findings of cephalocranial disproportion. Resolution of symptoms was documented in that publication. In this current study, we analyzed postdistraction intracranial volume changes in 11 consecutive patients retrospectively from 10/2001 to 11/2010 with institutional review board approval. These 11 patients were treated by cranial vault distraction osteogenesis for symptomatic cephalocranial disproportion. Pre- and postoperative CT DICOM data were analyzed using specialized software to generate finite element models. Intracranial and ventricular volumes were calculated. Topographical surface maps were generated to document and quantify areas of change. Possible effects on brain physiology are discussed. Pre- and postoperative CT scans were obtained at an average of 3.5 months prior to, and 4.2 months following distraction, respectively. Average age at distraction was 55.72 months (range 26–104 months). Operative time averaged 2 h 44 min (range 127–198 min, SD = 30.6). Intracranial and ventricular volumes increased by an average of 77.01 and 4.85 ml, respectively. Nonventricular intracranial volumes increased by 5.91%, 71.67 ml following distraction. All postoperative volume changes were statistically significant (p ≤ 0.000025). The ability to use the same methodology to quantify ventricular volume changes was unexpected. The fact that all ventricles expanded after distraction at approximately 10% of the total intracranial volume increase indicates that compensatory mechanisms had been activated. We conclude that this occurs at the expense of cerebral blood flow.

Hydrocephalus and Chiari type I malformation

[corrected] Hydrocephalus has been related to Chiari type I malformation (CIM) for a long time. The pathogenesis of this association is complex and still debated. A supratentorial hypertensive hydrocephalus may cause CIM, exerting pressure from above. Another pathogenetic hypothesis is based on the clinical and radiological data from patients affected by complex craniosynostosis, in which this association is more commonly observed as the consequence of a "cephalo-cranial disproportion" ultimately leading to a secondary hydrocephalus. In some cases, the concomitant presence of a stenosis of the jugular foramina would determine a condition of upward venous hypertension, resulting in the development of CIM and an associated hydrocephalus due to cerebellar parenchyma turgor. The radiological association of ventricular enlargement and hindbrain herniation would be the result of heterogeneous pathogenetic mechanisms which would then require specific therapeutic approaches. In this context, the endoscopic third ventricle-cisternostomy is gaining an increasing interest because of its more physiologic correction of the altered CSF dynamics and its minor interference on the developmental processes responsible for the association of hydrocephalus and CIM.

Internal Distraction Osteogenesis to Correct Symptomatic Cephalocranial Disproportion

Cephalocranial disproportion describes a state of volume mismatch between brain size and intracranial space. Nonsyndromic single-suture craniosynostosis patients can present with symptoms from elevated intracranial pressure because of inadequate or delayed treatment. The purpose of this study was to present five sagittal synostosis children with symptomatic cephalocranial disproportion treated with cranial vault distraction osteogenesis. Asymmetric transverse internal distraction osteogenesis was performed to preferentially expand the posterior cranium. A wider base plate, pivot screw, anterior hinge plate, and flexible drive rod were applied to minimize device failure while accomplishing lateral rotation of parietal bones. A distraction protocol was developed and produced consistent results. Two girls and three boys underwent distraction for sagittal synostosis between 2002 and 2006. Average age at surgery was 5.8 years. All had resolution or amelioration of preoperative symptoms. Average operating room time for distractor placement was 2.5 hours (152 minutes) and average hospital stay was 2.8 days. The average distracted distance was 14.4 mm. Average operating room time for distractor removal was 1.1 hours (69 minutes) and average hospital stay was 1.6 days. No perioperative complications occurred. Average follow-up period was 4.2 years, with no recurrence of symptoms. Symptomatic cephalocranial disproportion can present in older children with craniosynostosis. Asymmetric transverse distraction of the posterior cranial vault is a safe and effective treatment modality for this population.

Evolution of tonsillar ectopia associated with frontal encephalocoele

Chiari I malformation has been traditionally considered a congenital malformation. However, there is growing clinical evidence suggesting that it is an acquired phenomenon as also exemplified by this case. Fetal magnetic resonance imaging (MRI) at 28th week gestation revealed a frontonasal encephalocoele with no hindbrain abnormalities. Post-natal MRI of brain and cervical spine of the 7-week-old infant showed the presence of tonsillar ectopia in the absence of hydrocephalus. The normally developed cerebellar tonsil has herniated through the foramen magnum during the third trimester and neonatal period. We hypothesise that the presence of the encephalocoele resulted in dampening expansile forces, produced by the growing brain as well as the cerebrospinal fluid pulsation required to stimulate of the skull growth. As a result, cranial growth is diminished producing a small posterior fossa. The subsequent growth spurt of the cerebellum at the end of the third trimester and during the neonatal period has resulted in cerebellar tonsillar ectopia consequent upon the state of cephalocranial disproportion.

Chiari I anatomy after ventriculoperitoneal shunting: posterior fossa volumetric evaluation with MRI

Cephalocranial disproportion was said to be responsible for Chiari I malformation after ventriculoperitoneal shunt. We aimed to evaluate if the volumetric characteristics of Chiari I after a ventriculoperitoneal shunt was due to a general volumetric reduction and if it is restricted to the posterior fossa. Our results show that the posterior fossa volume, cisternal, clival length, and posterior cranial fossa volume ratio were reduced in the shunted group compared to the controls (p<0.05). Cerebellar and supratentorial volumes were similar between both groups. Craniocaudal extent, inferior, and superior tonsillar herniations were greater in the shunted group than control (p<0.05). The frontal occipital horn ratio in both groups was within normal range. Chiari I anatomy after a ventriculoperitoneal shunt could develop in children and we propose a "posterior cranial fossa disproportion" rather than a "cephalocranial disproportion."

Chiari 1 anatomy following ventriculoperitoneal shunting:Posterior fossa volumetric evaluation with MRI

Cephalocranial disproportion has been said to be responsible for Chiari 1 malformation following ventriculo-peritoneal shunt. We aimed to evaluate if the volumetric characteristics of Chiari 1 following a ventriculo-peritoneal shunt was due to a general volumetric reduction or restricted to the Posterior fossa. Our results show that the posterior fossa volume, cisternal, clival length and posterior cranial fossa volume ratio were reduced in the shunted group compared to the controls. p<0.05. Cerebellar and Supratentorial volumes were similar between both groups. Craniocaudal extent, inferior and superior tonsilar herniations were more in the shunted group than controls. p<0.05 . The frontal occipital horn ratio in both groups was within normal range. Chiari 1 anatomy following a ventriculo-peritoneal shunt could develop in children and we propose a ‘Posterior cranial fossa disproportion’ rather than a ‘Cephalocranial disproportion’.

Cephalocranial Disproportion

Eight children with hydrocephalus showed signs of posterior fossa tonsillar impaction despite arrest of the hydrocephalus and patency of their CSF shunts. Contrast studies performed because of their clinical deterioration demonstrated cerebellar tonsillar herniation, and at posterior fossa decompression, this was confirmed in all cases. Improvement followed decompression. The pathogenesis of a state of cephalocranial disproportion following successful treatment of hydrocephalus resulting in symptomatic tonsillar herniation, is discussed.