Brain anomalies in 121 children with non-syndromic single suture craniosynostosis by MR imaging

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.

Cognitive performance in preschoolers with non-syndromic craniosynostosis undergoing surgery: A comparison with typically developing children

This study aimed to determine the cognitive profile of preschool children undergoing surgery to correct non-syndromic craniosynostosis, compare them with typically developing children, and analyze possible cognitive deficits in the most prevalent subtypes: sagittal and unicoronal. Thirty-one children aged 3 years to 5 years and 11 months with non-syndromic craniosynostosis (11 sagittal, 9 unicoronal, 4 metopic, 3 lambdoid, 4 multisutural) who underwent surgery were compared with thirty-one typically developing children. The Wechsler Preschool and Primary Scale of Intelligence-Third Edition (WPPSI-III) was used to assess cognitive function. Children with non-syndromic craniosynostosis scored below the typically developing children in the Verbal Intelligence Quotient (VIQ) and Full-Scale Intelligence Quotient (FISQ). When specific subtypes were compared, children with sagittal synostosis scored similarly to the typically developing children; in contrast, children with unicoronal synostosis had lower performance in the Processing Speed Quotient and FISQ. The proportion of participants scoring below one standard deviation on the VIQ, General Language Composite, and FISQ was greater in the non-syndromic craniosynostosis group. This study supports the finding that children with non-syndromic craniosynostosis, particularly those with unicoronal synostosis, have more cognitive difficulties than those with normal development. Assessing cognition at preschool age in children with non-syndromic craniosynostosis is important in order to detect difficulties before they become more apparent at school age.

MR Protocols for Paediatric Neurosurgical Common Conditions: An Update Guide for Neurosurgeons

The biggest challenge for clinicians and surgeons when it comes to radiological examinations is the ability to request the right modalities and to understand the strengths and limitations of each modality. This is particularly important in paediatric neurosciences where despite magnetic resonance imaging (MRI) being the main imaging modality, there are several protocols, technical limitations of specific scanners and issues related to sedation that need to be taken into account. In this chapter, we describe a simple approach for six common neurosurgical conditions to guide the paediatric neurosurgeons in requesting the right MR protocol and understanding the rationale of it.Paediatric neuro-oncology, epilepsy and neck/skull base protocols are discussed elsewhere in this book and therefore will not be a focus in this chapter (Bernasconi et al., Epilepsia 60:1054-68, 2019; D'Arco et al., Neuroradiology 64:1081-100; 2022; Avula et al., Childs Nerv Syst 37:2497-508; 2021).

Scaphocephaly and increased intra-cranial pressure in non-operated adults: A controlled anthropological study on 21 skulls

AIM AND SCOPE

The prevalence of increased intra-cranial pressure (ICP) in patients with scaphocephaly is controversial. Here, based on anthropological material, we aimed to determine whether adults with non-operated sagittal synostosis show indirect signs of increased ICP.

MATERIALS AND METHODS

Thirty-eight dry skulls (21 skulls with sagittal craniosynostosis and 17 controls) were selected from the collections of the National Museum of Natural History (Paris, France). All skulls registered as 'fused sagittal suture' or 'scaphocephaly' in the registry of the Museum were included. All had total fusion of the sagittal suture. Controls were selected within skulls of similar origin (France), without visible craniofacial anomalies. The 38 skulls were CT-scanned using a standard medical CT-scan with a protocol dedicated to dry bone imaging. Eight radiological signs associated with raised ICP were assessed: (1) calvaria and (2) skull base thinning, (3) dorsum sellae erosion, (4) sella turcica lengthening, (5) copper beaten skull, (6) suture diastasis, (7) persistent metopic suture, and (8) small frontal sinus. Scaphocephaly was assessed based on head circumference, cranial index, intra-cranial volume, fronto-nasal angle, and inter-zygomatic distance. Linear and non-linear logistic models were used to compare groups.

RESULTS

19/21 skulls with sagittal synostosis were significantly scaphocephalic. None of the criteria for ICP were significantly different in skulls with scaphocephaly relative to controls. Nevertheless, 5 individual skulls with scaphocephaly had ≥ 3 signs in favor of a history of raised ICP. We do not report the significant prevalence of indirect signs of raised ICP in adults with scaphocephaly. These results do not allow ruling out a history of early raised ICP or of minor prolonged raised ICP. Even though our findings support the fact that scaphocephaly is not significantly associated with prolonged raised ICP, individual cases (5/21) with clear signs in favor of a history of brain compression indicate that scaphocephaly correction should be considered as a functional procedure until the production of clear evidence. Cognitive assessments of non-operated adult patients with scaphocephaly could contribute to tackle this recurring question in craniofacial surgery.

Cognitive performance of preschool children with different types of non-syndromic craniosynostosis

Background:

Craniosynostosis is defined as a premature fusion of one or more cranial sutures. Several studies have revealed cognitive deficits in some children who had undergone surgery to treat craniosynostosis. However, no general distinction has been drawn in the cognitive abilities between the various types of craniosynostosis. The purpose of the present study was to analyze if there is a difference in cognitive and motor function among the different types of non-syndromic craniosynostosis in preschool children.

Methods:

Twenty-seven children with different types of non-syndromic craniosynostosis were assessed using the Wechsler Preschool and Primary Scale of Intelligence – Third Edition, as well as the Quantitative, Memory and Motor scales of McCarthy Scales of Children’s Abilities (MSCA). The children were aged between 3 and 5 years and 11 months. The various types of craniosynostosis were compared.

Results:

The unicoronal synostosis group performed significantly worse than the multisuture synostosis group on the MSCA Motor scale. No differences in cognitive functions were found between the various types of craniosynostosis.

Conclusions:

Children with unicoronal synostosis may experience impaired motor skills and screening of their motor ability is recommended.

Intracranial pressure, brain morphology and cognitive outcome in children with sagittal craniosynostosis

BACKGROUND

Patients with sagittal craniosynostosis are at increased risk of developing raised intracranial pressure (ICP) and neurocognitive deficiencies such as reduced attention, planning, speech, behavioural and learning disabilities.

AIM

To determine if the existing literature supports a correlation between elevated ICP and negative cognitive outcome in patients with sagittal craniosynostosis. Secondly, to investigate if the risk of developing neurocognitive deficiencies can be explained by changes in brain morphology in this patient category.

METHODS

Systematic literature review in PubMed.

RESULTS

A total of 190 publications were reviewed to determine a possible correlation between raised ICP and cognitive outcome, of which four were included in the study. No significant association was found. Forty-four publications on brain morphology in sagittal craniosynostosis were identified, of which 11 were included in the review. Clear evidence of morphologic changes in multiple areas of the brains of sagittal craniosynostosis patients was found in the literature.

CONCLUSION

The existing literature does not support an association between increased ICP and negative global cognitive outcome measures in patients with sagittal craniosynostosis. Brain morphology is altered in areas related to neurocognition and language in the same patient group. These changes might play a role in the development of neurocognitive deficiencies, though no definitive link is yet established, and further investigation is warranted.

Chiari I malformation in defined genetic syndromes in children: are there common pathways?

PURPOSE

Chiari malformation type I (CMI) is a common pediatric neurologic anomaly that can be associated with a variety of genetic disorders; however, it is not always clear whether the observed associations are real or random. The knowledge of the real associations could provide useful guidance to clinicians. Furthermore, it could be of help to better understand the still unknown genetic etiology of CMI.

METHODS

With the aim of implementing such insights, we retrospectively reviewed clinical, neuroradiological, and genetic data of patients harboring CMI evaluated at the Child Neurology Unit of our institution between January 2008 and December 2018.

RESULTS

The cohort consists of 205 patients (111 males and 94 females), with a mean age at diagnosis of 6.3 years (range 0-18 years). 188 patients completed an average follow-up period of 5.2 years (range one month-18 years). Mean age at last assessment was 11.4 years (range nine months-23 years). 127 (62%) children have been classified as syndromic due to the presence of neurodevelopmental disorders, phenotypic anomalies, or malformations. Among syndromic CMI children, a molecular diagnosis was identified in 35/127 (27.6%) (20 males and 15 females). The most common diagnoses were syndromic craniosynostosis in 8/35 children (22.9%), among which sevenare FGFR-related and one ERF-related craniosynostosis; disorders of the RAS/MAPK pathway, termed RASopathies or RAS/MAPK syndromes in 9/35 (25.7%); disorders of the PTEN-PI3K/AKT signal transduction cascade, termed PTENopathies in 3/35 children (8.6%); and chromosomal rearrangements in 6/35 patients (17.1%), two of whom with del16p11.2.

CONCLUSIONS

We polarized our attention on the defined genetic diagnoses focusing not only on the phenotypic hallmarks but also on the phenotypic overlapping features. In addition, we discussed the pathophysiological mechanisms leading to progressive cerebellar ectopia and the involved molecular pathways. Along with the recent literature evidence, we suppose that interactions between FGFR and RAS/MAPK pathway and between RAS/MAPK and PTEN-PI3K/AKT pathways could explain some phenotypic overlapping features and could have a significant role in the pathogenesis of CMI.

Which neuroimaging techniques are really needed in Chiari I? A short guide for radiologists and clinicians

PURPOSE

To describe the most appropriate techniques and suggested protocols meant to address the various scenarios that clinicians and pediatric neurosurgeons may face in their day-to-day practice connected with Chiari I.

METHODS

Current literature related to image indications and findings in Chiari I has been reviewed. The authors focused on both standard and advanced techniques for clinical diagnosis and preoperative planning purposes.

DISCUSSION AND CONCLUSION

The complexity of providing neuroimaging guidelines for children investigated for Chiari I lies in defining the most appropriate neuroradiology tool to approach what is in fact a very heterogeneous condition with different etiopathogenetic mechanisms and associated abnormalities. Other variables that may influence the diagnostic strategy include the age of the patient, the presence of additional pathological conditions, the type of presenting symptoms, and the indication for surgical or conservative management. Although the average age at time of diagnosis is 10 years, the initial diagnosis may be done at any age, and the referral for neuroradiology workup may come from general practitioners/pediatricians, orthopedic surgeons, and endocrinologists following various baseline investigations including plain x-rays of skull and spine and/or CT head and/or MRI brain and spine.

The Incidence of Chiari Malformations in Patients with Isolated Sagittal Synostosis

Background:

We report the incidence of Chiari malformation I (CMI) in a cohort of 377 patients with isolated sagittal synostosis (ISS), which is to the best of our knowledge the largest such series reported to date.

Methods:

A retrospective review of patients seen at a single institution from 2007 to 2017 was completed. ISS, Chiari malformations (CMI and CMII) and hydrocephalus were diagnosed by a senior neuroradiologist (G.Z.). Patients who met the inclusion criteria were divided into early (group A) and late (group B) presenting groups, as well as operated (group I) and unoperated (group II) groups. The patients were further subdivided into group AI (early operated), group AII (early unoperated), group BI (late operated), and group BII (late unoperated). Once identified, patient notes were examined for the following data sets: date of birth, age of presentation, age at last follow-up, other systemic conditions as well as molecular testing results. Surgical interventions, ophthalmological, and other relevant data were recorded. Statistical analysis was run in the form of a chi-square test to identify a significant difference between each subgroup. A literature review of the incidence of Chiari malformations in patients with ISS was conducted.

Results:

Three hundred seventy-seven patients constitute the study’s total cohort (272 were males and 105 females). This cohort was divided into patients who underwent surgical repair of ISS (group 1: n = 200), and patients who did not (group 2: n = 177). The entire cohort was also divided into early (group A: n = 161) and late (group B: n = 216) presenting craniosynostosis. In the total cohort, 22/377 (5.8%) patients with CMI were identified. CMI was found in 14/200 (7.0%) patients in group I, and 8/177 (4.5%) patients in group II. CMI was found in 2/161 (1%) patients in group A, and 20/216 (9.2%) patients in group B. The incidence of CMI in group AI (early operated) was 2/151 (1.3%), in group AII (early unoperated) was 0/10, in group BI (late operated) was 11/49 (21%), and in group BII (late unoperated) was 9/167 (5.4%). Chi-square analysis revealed a significant difference between the incidence of CMI in the early-presenting (group A) and late-presenting (group B) groups (P = 0.001) and between the late-presenting operated (BI) and late-presenting unoperated (BII) groups (P = 0.001). The incidence of hydrocephalus was 1.6% (6/377) in the total cohort. However, all patients diagnosed with hydrocephalus came from group II (no surgical ISS correction). The incidence of hydrocephalus in group II was 3.3% (6/177). The incidence of hydrocephalus in group BII (late unoperated ISS) was 3.0% (5/167). The incidence of hydrocephalus in group AII (early unoperated ISS) was 9.0% (1/11).

Conclusions:

We noted the highest incidence of CMI—21%—in group BI (late-presenting operated). We noted hydrocephalus in group II (nonoperated), with the highest incidence of hydrocephalus found in the group BII (late-presenting unoperated) subgroup. We therefore recommend patients with ISS receive funduscopic examination to screen for raised intracranial pressure (ICP) associated with CMI and hydrocephalus, especially patients with late-presenting ISS.

The Etiology of Neuronal Development in Craniosynostosis: A Working Hypothesis

Craniosynostosis is one of the most common craniofacial conditions treated by neurologic and plastic surgeons. In addition to disfigurement, children with craniosynostosis experience significant cognitive dysfunction later in life. Surgery is performed in infancy to correct skull deformity; however, the field is at a crossroads regarding the best approach for correction. Since the cause of brain dysfunction in these patients has remained uncertain, the role and type of surgery might have in attenuating the later-observed cognitive deficits through impact on the brain has been unclear. Recently, however, advances in imaging such as event-related potentials, diffusion tensor imaging, and functional MRI, in conjunction with more robust clinical studies, are providing important insight into the potential etiologies of brain dysfunction in syndromic and nonsyndromic craniosynostosis patients. This review aims to outline the cause(s) of such brain dysfunction including the role extrinsic vault constriction might have on brain development and the current evidence for an intrinsic modular developmental error in brain development. Illuminating the cause of brain dysfunction will identify the role of surgery can play in improving observed functional deficits and thus direct optimal primary and adjuvant treatment.

Delayed Presentation of Isolated Sagittal Synostosis With Raised Intracranial Pressure and Secondary Chiari Malformation With Cervical Syringomyelia

Sagittal craniosynostosis (SC) is the most common type of premature suture fusion presenting in approximately 1 in every 5000 births with a 3:1 male:female ratio. The most common indication for surgery is the improvement of the cosmetic appearance of the skull, since a cranial deformation may have a significant psychosocial impact on affected patients. Relief from raised intracranial pressure is a further indication for surgery, although an increased intracranial pressure (ICP) can be demonstrated only in a minority of affected children at diagnosis. It is even more rare to have Chiari malformations (CMs) secondary to ICP in an isolated SC, as shown in a study by Strahle et al (Neurosurg Focus 2011;31:E2), demonstrating only 5 (3%) of the 183 with isolated sagittal synostosis having a CM. The authors present the rare case of a 4-year-old boy presenting late with raised intracranial pressure (40 mm Hg) and his management with 1 stage vault expansion and decompression of CM.

Structural brain differences in school-age children with and without single-suture craniosynostosis

OBJECTIVE Single-suture craniosynostosis (SSC), the premature fusion of a cranial suture, is characterized by dysmorphology of the craniofacial skeleton. Evidence to suggest that children with SSC are at an elevated risk of mild to moderate developmental delays and neurocognitive deficits is mounting, but the associations among premature suture fusion, neuroanatomy, and neurocognition are unexplained. The goals of this study were to determine 1) whether differences in the brain are present in young children with the 2 most common forms of SSC (sagittal and metopic) several years following surgical correction, and 2) whether the pattern of differences varies by affected suture (sagittal or metopic). Examination of differences in the brains of children with SSC several years after surgery may illuminate the growth trajectory of the brain after the potential constraint of the dysmorphic cranium has been relieved. METHODS The authors compared quantitative measures of the brain acquired from MR images obtained from children with sagittal or metopic craniosynostosis (n = 36) at 7 years of age to those obtained from a group of unaffected controls (n = 27) at the same age. The authors measured the volumes of the whole brain, cerebral cortex, cerebral white matter, cerebral cortex by lobe, and ventricles. Additionally, they measured the midsagittal area of the corpus callosum and its segments and of the cerebellar vermis and its component lobules. Measurements obtained from children with SSC and controls were compared using linear regression models. RESULTS No volume measures of the cerebrum or of the whole brain differed significantly between patients with SSC and controls (p > 0.05). However, ventricle volume was significantly increased in patients with SSC (p = 0.001), particularly in those with sagittal craniosynostosis (p < 0.001). In contrast, the area of the corpus callosum was significantly reduced in patients with metopic synostosis (p = 0.04), particularly in the posterior segments (p = 0.004). Similarly, the area of lobules VI-VII of the cerebellar vermis was reduced in patients with SSC (p = 0.03), with those with metopic craniosynostosis showing the greatest reduction (p = 0.01). CONCLUSIONS The lack of differences in overall brain size or regional differences in the size of the lobes of the cerebrum in children with metopic and sagittal synostosis suggests that the elevated risk of neurodevelopmental deficits is not likely to be associated with differences in the cerebral cortex. Instead, this study showed localized differences between sagittal and metopic craniosynostosis cases as compared with controls in the ventricles and in the midsagittal structures of the corpus callosum and the cerebellum. It remains to be tested whether these structural differences are associated with the increased risk for developmental delay and neurocognitive deficits in children with SSC.

Contemporary occurrence of hydrocephalus and Chiari I malformation in sagittal craniosynostosis. Case report and review of the literature

Chiari malformation type I (CM-I) and hydrocephalus are often associated with complex craniosynostosis. On the contrary, their simultaneous occurrence in monosutural synostosis is extremely rare. The pathophysiological hypothesis is that they may alter posterior fossa growth and lead to cerebellar tonsil herniation also without skull base primary involvement. Hydrocephalus is multifactorial and may be secondary to fourth ventricle outlet obstruction. The management of these cases is quite complex and not well defined. Cranial vault remodeling should be the only treatment when CM-I is asymptomatic and not related to syringomyelia. Suboccipital decompression should be reserved only in complicated CM-I, usually as a second surgical step following the correction of the supratentorial deformity. In our opinion, the associated hydrocephalus should be treated first in order to normalize intracranial hypertension before opening the cranial sutures. We report the case of a 26-month-old child that presented with sagittal craniosynostosis, hydrocephalus, and CM-I. He was managed by performing endoscopic third ventriculostomy (ETV) first and cranial vault remodeling thereafter. Clinico-radiological outcome was very satisfying. Concerning literature is reviewed; physiopathology and surgical management are discussed.

Normalization of brain morphology after surgery in sagittal craniosynostosis

OBJECT Nonsyndromic craniosynostosis (NSC) is associated with significant learning disability later in life. Surgical reconstruction is typically performed before 1 year of age to correct the cranial vault morphology and to allow for normalized brain growth with the goal of improving cognitive function. Yet, no studies have assessed to what extent normalized brain growth is actually achieved. Recent advances in MRI have allowed for automated methods of objectively assessing subtle and pronounced brain morphological differences. The authors used one such technique, deformation-based morphometry (DBM) Jacobian mapping, to determine how previously treated adolescents with sagittal NSC (sNSC) significantly differ in brain anatomy compared with healthy matched controls up to 11.5 years after surgery. METHODS Eight adolescent patients with sNSC, previously treated via whole-vault cranioplasty at a mean age of 7 months, and 8 age- and IQ-matched control subjects without craniosynostosis (mean age for both groups = 12.3 years), underwent functional 3-T MRI. Statistically significant group tissue-volume differences were assessed using DBM, a whole-brain technique that estimates morphological differences between 2 groups at each voxel (p < 0.01). Group-wise Jacobian volume maps were generated using a spacing of 1.5 mm and a resolution of 1.05 × 1.05 × 1.05 mm(3). RESULTS There were no significant areas of volume reduction or expansion in any brain areas in adolescents with sNSC compared with controls at a significance level of p < 0.01. At the more liberal threshold of p < 0.05, two areas of brain expansion extending anteroposteriorly in the right temporooccipital and left frontoparietal regions appeared in patients with sNSC compared with controls. CONCLUSIONS Compared with previous reports on untreated infants with sNSC, adolescents with sNSC in this cohort had few areas of brain dysmorphology many years after surgery. This result suggests that comprehensive cranioplasty performed at an early age offers substantial brain normalization by adolescence, but also that some effects of vault constriction may still persist after treatment. Specifically, few areas of expansion in frontoparietal and temporooccipital regions may persist. Overall, data from this small cohort support the primary goal of surgery in allowing for more normalized brain growth. Larger samples, and correlating degree of normalization with cognitive performance in NSC, are warranted.

Clinical and neuroradiological features of the 9p deletion syndrome

BACKGROUND

The 9p deletion syndrome is a rare condition, which associates trigonocephaly, facial dysmorphism and developmental delay. The neuroradiological aspects of this syndrome have not yet been described. The purpose of this article is to identify the clinical and neuroradiological features, that should be recognized by all specialists treating these children, for a proper and early diagnosis.

METHODS

Among patients with trigonocephaly treated at our institution, we retrospectively analyzed the clinical and neuroradiological aspects of children with genetically confirmed 9p deletion syndrome.

RESULTS

6 patients were identified. Beside trigonocephaly, the most frequent clinical findings were small ears, long philtrum, upslanting palpebral fissures, flat nasal bridge and variable psycho-motor delay. Hypertelorism was present in 4 of 6 patient, which is opposite to the hypotelorism typical of non-syndromic trigonocephaly. Among neuroradiological findings, large, anteriorly rotated sylvian cisterns and altered shape of the septum pellucidum were found in all patients, as well as the compression of the frontal cortex due to the metopic synostosis (MS). A thin or dysmorphic corpus callosum and a diffuse white matter hypoplasia were present in more than half of the cases. Futhermore we compared these MRI findings with those of a control group of 30 non-syndromic trigonocephalies.

CONCLUSIONS

Some recurrent neuroradiological alterations can be found in 9p deletion syndrome. The presence of these signs on MRI of a trigonocephalic patient should raise the suspicion of an underlying chromosomal alteration, such as the 9p deletion syndrome and prompt genetic investigations.

Skull base development and craniosynostosis

Abnormal skull shape resulting in craniofacial deformity is a relatively common clinical finding, with deformity either positional (positional plagiocephaly) or related to premature ossification and fusion of the skull sutures (craniosynostosis). Growth restriction occurring at a stenosed suture is associated with exaggerated growth at the open sutures, resulting in fairly predictable craniofacial phenotypes in single-suture non-syndromic pathologies. Multi-suture syndromic subtypes are not so easy to understand without imaging. Imaging is performed to define the site and extent of craniosynostosis, to determine the presence or absence of underlying brain anomalies, and to evaluate both pre- and postoperative complications of craniosynostosis. Evidence for intracranial hypertension may be seen both pre- and postoperatively, associated with jugular foraminal stenosis, sinovenous occlusion, hydrocephalus and Chiari 1 malformations. Following clinical assessment, imaging evaluation may include radiographs, high-frequency US of the involved sutures, low-dose (20-30 mAs) CT with three-dimensional reformatted images, MRI and nuclear medicine brain imaging. Anomalous or vigorous collateral venous drainage may be mapped preoperatively with CT or MR venography or catheter angiography.

Asymmetric laterality of Chiari type I malformation in patients with non-syndromic single-suture craniosynostosis

BACKGROUND

Chiari type I malformation is a frequent incidental finding commonly associated with craniosynostosis. However, there seems to be a paucity of literature concerning the asymmetry of tonsillar herniation in patients with non-syndromic single-suture craniosynostosis.

METHODS

To study the asymmetry in this cohort, measurements of the right and left tonsils were made from sagittal images from both pre-operative and post-operative images from 11 patients with non-syndromic single-suture craniosynostosis.

RESULTS

Pre-operatively, the mean difference between the caudal descent of all tonsils ranged from 0 to 7 mm, with a mean difference between sides of 2.45 mm. In three cases, cerebellar tonsils were symmetrically herniated. Post-operatively, the mean difference between caudal descent of all tonsils ranged from 0 to 4 mm, with a mean difference between sides of 1.45 mm. Four were symmetrically herniated. In patients with non-syndromic single-suture craniosynostosis, the tonsillar herniation is asymmetric in the majority of cases.

CONCLUSIONS

Asymmetry of cerebellar tonsil herniation is a frequent finding in this cohort. The right tonsil is more inferiorly located in majority of cases, with predominance to the synostotic suture side in asymmetric craniosynostosis cases.

The evolution of cerebellar tonsillar herniation after cranial vault remodeling surgery

PURPOSE

We sought to examine the pre- and postoperative changes of cerebellar tonsillar herniation by MR imaging in asymptomatic pediatric patients with nonsyndromic, single-suture craniosynostosis (N-SSSC), who underwent cranial vault remodeling surgery without suboccipital decompression. We required cerebellar tonsillar herniation through foramen magnum ≥3 mm for Chiari type I malformation (CMI). We hypothesized that the increase of intracranial volume by cranial vault remodeling would correct the asymptomatic CMI.

METHODS

We identified 9 patients among 121 N-SSSC children undergoing craniofacial surgery from January 2004 to October 2010 with CMI. However, two of them were excluded from the study due to missing postoperative MR images. In the final study population, six were males, five were scaphocephalic, while two were diagnosed with coronal synostosis.

RESULTS

In four of the cases, the CMI was decreased in postoperative MR imaging varying from 6 to 12 mm. In three cases, the herniation remained stable. The median change of cerebellar tonsillar herniation was -6.5 mm.

CONCLUSIONS

We conclude that asymptomatic patients with existing CMI may benefit from cranial vault remodeling surgery alone increasing the intracranial volume.