Hydrocephalus and craniosynostosis

Complex craniosynostoses: a review of the prominent clinical features and the related management strategies

The protocols for clinical evaluation and management of children with complex craniosynostoses are significantly different from those used in single suture forms. The time at which the various anatomical and functional anomalies observed in the affected subjects become clinically relevant varies from patient to patient, consequently requiring a tailored approach. The clinical course is variable and influenced by multiple factors, acting at different steps of the children growth. Intracranial hypertension is a major concern already in the first months of life; active cerebrospinal fluid (CSF) dynamics disorders, venous hypertension, and progressive craniocerebral disproportion are considered the main pathogenetic factors. Cranial vault and skull base sutures synostoses account for the frequently observed increased venous pressure. Skull base abnormalities lead to upper airways obstruction, which, on one side, might create significant upper airways obstructive problems and, on the other, contribute to the increase in the intracranial pressure. Secondary Chiari malformation is common and considered as a progressive disorder, mainly due to progressive craniocerebral disproportion, venous hypertension, and CSF dynamics disorders. Optic nerve and orbit-related eye-globe diseases are also a major concern. Papilledema is mostly related to increased intracranial pressure. The skull base synostotic process is the base of significant abnormalities of the orbital space, ending in the common feature of significant proptosis with the consequent risk of corneal ulcers. Aims of this paper are to analyze the physiopathogenetic mechanisms at the base of the clinical manifestations presented by children with complex craniosynostoses, and the therapeutic options currently available.

Non-syndromic oxycephaly and brachycephaly: a review

BACKGROUND

Non-syndromic coronal synostoses oxycephaly and brachycephaly (NSCSOB) are rare. Their natural history, surgical management, and outcome are debated.

MATERIAL AND METHODS

We reviewed the available literature on NSCSOB. In addition, we reviewed retrospectively our experience with cases of NSCSOB, managed and operated by our joint craniofacial team since 1984. Newborns underwent perifrontal craniectomy, while infants and older children underwent fronto-orbital advancement with frontoparietal remodeling. Cases with delayed onset of faciosynostosis were excluded.

RESULTS

Some cases of NSCSOB present at birth or even prenatally with gross dysmorphism and severe brachycephaly; others present later in life with harmonious restriction of intracranial volume and are at risk for development and vision. Some NSCSOB evolve from initially unisutural synostoses. We treated 61 cases, operated aged 1.4 to 106.7 months, 30 with brachycephaly and 31 with oxycephaly. Twelve of these (19.7 %), had been treated initially for sagittal or unicoronal synostosis, and evolved into NSCSOB. Intracranial hypertension was present initially in 28 (45.9 %), with ophthalmological consequences in 13 (21.3 %) and mental retardation in 6 (9.6 %). No patient had hydrocephalus; only two had asymptomatic Chiari malformation. The mean postoperative follow-up was 113.6 months. At last control, 21 patients had developmental delay and 5 had visual impairment.

CONCLUSIONS

NSCSOB are a complex entity. They have in common a high risk of severe intracranial hypertension and rare hydrodynamic complications. Genetic screening is necessary to assert their non-syndromic nature. Prolonged follow-up of all craniosynostoses is necessary because unisutural synostoses can evolve into NSCSOB, and NSCSOB can evolve into craniofaciosynostosis.

Craniosynostosis

Craniosynostosis is a complex condition, characterized by the premature fusion of one of more of the cranial sutures. They can be seen individually or as part of multisystem syndromes. This review uses computed tomography (CT) with three-dimensional reconstructions to help describe some of the types and classifications of craniosynostosis, as well as describing some of the associations and the management of craniosynostosis.

Nonsyndromic craniosynostosis

Nonsyndromic craniosynostosis is more commonly encountered than syndromic cases in pediatric craniofacial surgery. Affected children display characteristic phenotypes according to the suture or sutures involved. Restricted normal growth of the skull can lead to increased intracranial pressure and changes in brain morphology, which in turn may contribute to neurocognitive deficiency. Management has primarily focused on surgical correction of fused sutures prior to 12 months of age to optimize correction of the deformity and to ameliorate the effects of increased intracranial pressure. However, emphasis has recently shifted to better understanding the pathogenesis of neurocognitive impairment observed in these children, along with genetic mutations that contribute to premature suture fusion. Such understanding will provide opportunities for earlier and more specific neurocognitive interventions and for the development of targeted genetic therapy to prevent pathologic suture fusion. The authors review the common types of nonsyndromic craniosynostosis and the epidemiological, genetic, and neurodevelopmental details that are currently known from the literature. In addition, they present the rationale for surgical correction, offer suggestions for timing of intervention, and present some nuances of techniques that they find important in producing consistent results.

Cloverleaf skull deformity and hydrocephalus

OBJECTIVE

This article describes the clinical aspects for both operated and non-operated patients with a cloverleaf skull deformity treated in our service, focusing on hydrocephalus.

METHODS

We describe 13 cases of cloverleaf skull deformity treated in our services between 1977 and 2008. Among them, ten were operated (9 out of 13 for the craniofacial stenosis and 7 out of 13 for hydrocephalus).

RESULTS

Hydrocephalus was present in all patients with bilateral lambdoid stenosis. There was no case of hydrocephalus among the patients with unilateral or absent lambdoid stenosis. Associated malformations and severe faciostenosis were associated with higher mortality and morbidity.

CONCLUSION

The development of hydrocephalus seems to be closely related to a bilateral lambdoid stenosis. The optimal treatment must be tailored individually considering the degree of the malformation and the presence of complications and comorbidities.

Hydrocephalus and Chiari type I malformation

INTRODUCTION

[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.

DISCUSSION

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.

CONCLUSIONS

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.

Visual field loss in children with craniosynostosis

AIMS

To identify visual field deficits in a group of children with syndromic craniosynostosis.

METHODS

Kinetic visual field examination and visual evoked potentials (VEPs) were recorded in 16 children with syndromic craniosynostosis as part of their ophthalmic evaluation. VEPs were analyzed for inter-hemispheric asymmetries and component amplitude and latency, while visual fields were analyzed both qualitatively and quantitatively.

RESULTS

All children with craniosynostosis were found to have visual field deficits compared to controls. In the Crouzon group, deficits tended to involve the nasal field, while infero-nasal field deficits were the most consistent finding in children with Apert syndrome. Children with Pfeiffer's demonstrated the greatest deficits, with severe constrictions affecting the whole visual field. VEPs were asymmetrical in four cases while the P100 component was subnormal in ten of the 16 patients for either amplitude and/or latency.

CONCLUSION

Although we may speculate about the mechanisms that cause visual field deficits, we currently are unable to explain the reason for the differing types and extent of visual field loss in the different syndromic groups. We can conclude that the visual field deficits do indicate previous or ongoing visual dysfunction that cannot be monitored employing central vision tests alone.

Pseudotumor cerebri

INTRODUCTION

Pseudotumor cerebri is a condition characterized by raised intracranial pressure, normal CSF contents, and normal brain with normal or small ventricles on imaging studies. It affects predominantly obese women of childbearing age; however, its incidence seems to be increasing among adolescent and children. While among older children the clinical picture is similar to that of adults, younger children present demographic and clinical peculiarities. Different diagnostic criteria for adults and pre-pubertal children have been proposed. Etiology and pathogenesis are still unclear, particular concerning the role of obstruction to venous outflow.

METHODS

An extensive literature review concerning all the aspects of pseudotumor cerebri has been performed, both among adults and pre-pubertal children.

CONCLUSION

Pseudotumor cerebri is an avoidable cause of visual loss, both in adults and children. Few diagnostic measures are usually sufficient to determine the correct diagnosis. Since pseudotumor cerebri is a diagnosis of exclusion, the differential diagnosis work out is of special importance. Modern neuroimaging techniques, especially magnetic resonance imaging and magnetic resonance venography may clarify the role of obstruction to venous outflow in each case. Various therapeutic options are available: medical, surgical, and endovascular procedures may be used to prevent irreversible visual loss. Treatment is usually effective, and most patients will experience complete resolution of symptoms without persistent deficits.

The role of endoscopic third ventriculostomy in the treatment of hydrocephalus associated with faciocraniosynostosis

OBJECT

The aim of this study was to assess the efficacy of endoscopic third ventriculostomy (ETV) in the treatment of hydrocephalus in children with complex craniosynostosis.

METHODS

Medical charts from 2194 children treated at the Craniofacial Unit of Necker Enfants Malades between 1995 and 2008 were reviewed. Among them, 293 were affected by a syndromic faciocraniosynostosis. The management of cases with hydrocephalus treated using ETV was examined and analyzed with regard to successes and failures.

RESULTS

Forty-six children with associated progressive hydrocephalus were identified, and 11 (8 boys, 3 girls) had undergone an ETV. All were affected by a faciocraniosynostosis (Crouzon syndrome in 5, Pfeiffer syndrome in 3, and unclassifiable in 3). A descent of the cerebellar tonsils was found in 5 children. In 7 children the hydrocephalus was controlled by an ETV. In the remaining 4 cases a ventriculoperitoneal shunt was also needed. The delay between the 2 surgeries ranged from 1 week to 6 months in these 4 patients. The follow-up period ranged from 11 months to 13 years.

CONCLUSIONS

Performing an ETV may facilitate control of hydrocephalus associated with faciocraniosynostosis in select cases. However, because of the relatively high failure rate of this procedure, a close clinical and radiological monitoring of these children is mandatory.

Fetal constraint as a potential risk factor for craniosynostosis

Non-syndromic craniosynostosis is multifactorial, and fetal head constraint has been hypothesized as one factor thought to play a role. Data from the National Birth Defects Prevention Study (NBDPS), a large multi-site case-control study of birth defects, were used to evaluate associations between four selected factors related to fetal constraint and craniosynostosis: plurality (twins or higher), macrosomia (birth weight >4,000 g), post-term gestational age (> or =42 weeks), and nulliparity (no previous live births). Case infants (n = 675) had craniosynostosis documented either by radiographic evidence or by surgical intervention. Infants with a recognized or strongly suspected single-gene conditions or chromosomal abnormalities were excluded. Control infants (n = 5,958) had no major birth defects and were randomly selected from the same population as case infants. Logistic regression was used to estimate odds ratios for the association between these four factors and craniosynostosis, while adjusting for several covariates. We found that plurality and nulliparity were associated with a twofold increased risk for metopic craniosynostosis, and macrosomia had almost twice the risk of developing coronal craniosynostosis. Contrary to our hypothesis, prematurity and low birth weight were also associated with craniosynostosis. In conclusion, these four constraint-related factors were not found to be associated with craniosynostosis when all suture types were combined, though some types of craniosynostosis were associated with individual constraint-related factors.

Lessons from a case of osteopetrosis oxycephaly and Chiari type I malformation: a case report

We report a child with osteopetrosis, oxycephaly and Chiari type I malformation who presented with raised intracranial pressure. During cranial expansion surgery the patient developed sudden cardiac arrest which we believe was probably related to the Chiari malformation. The case highlights a previously unrecognized association between osteopetrosis, craniosynostosis and a persistently open fontanelle at age 4 years. In addition it supports the existing literature in emphasizing the need for careful preoperative work up, choice of approach and operative technique in children with complex craniosynostosis and Chiari malformation.

Reoperation for intracranial hypertension in TWIST1-confirmed Saethre-Chotzen syndrome: a 15-year review

BACKGROUND

Saethre-Chotzen syndrome is a syndromic craniosynostosis defined by a genetic mutation affecting the TWIST1 gene on chromosome 7p21. It is typically associated with unicoronal or bicoronal synostosis, eyelid ptosis, dysmorphic external ears, and other variable facial and limb abnormalities. Surgical management of the craniosynostosis addresses the calvarial deformity and may relieve or reduce the risk of intracranial hypertension. The aim of this study was to assess surgical intervention, with particular consideration of the reoperation rate for intracranial hypertension, in Saethre-Chotzen syndrome patients.

METHODS

A retrospective case note analysis was performed on all patients with a confirmed TWIST1 gene abnormality who attended the Oxford Craniofacial Unit over a 15-year period. Each patient's mutation and clinical features were recorded. Surgical intervention and sequelae were examined in greater detail.

RESULTS

Thirty-four patients with genetically confirmed Saethre-Chotzen syndrome were identified. All had craniosynostosis (bicoronal, 76 percent; unicoronal, 18 percent; bicoronal and sagittal, 6 percent), and the majority had eyelid ptosis, low frontal hairline, and external ear anomalies. Thirty-one patients had received surgical intervention. Nine of 26 patients (35 percent) with at least 12 months of follow-up after primary intervention and eight of 19 patients (42 percent) with at least 5 years of follow-up developed intracranial hypertension necessitating secondary calvarial surgery.

CONCLUSIONS

Despite standard surgical intervention, patients with Saethre-Chotzen syndrome have a high rate (35 to 42 percent) of recurrent intracranial hypertension necessitating further surgical expansion. All patients with either bicoronal synostosis or unicoronal synostosis with syndromic features should be screened for TWIST1 mutations, as this confers a greater risk than nonsyndromic synostosis of the same sutures. Regular follow-up throughout the childhood years is essential.

Craniosynostosis in the Middle Pleistocene human Cranium 14 from the Sima de los Huesos, Atapuerca, Spain

We report here a previously undescribed human Middle Pleistocene immature specimen, Cranium 14, recovered at the Sima de los Huesos (SH) site (Atapuerca, Spain), that constitutes the oldest evidence in human evolution of a very rare pathology in our own species, lambdoid single suture craniosynostosis (SSC). Both the ecto- and endo-cranial deformities observed in this specimen are severe. All of the evidence points out that this severity implies that the SSC occurred before birth, and that facial asymmetries, as well as motor/cognitive disorders, were likely to be associated with this condition. The analysis of the present etiological data of this specimen lead us to consider that Cranium 14 is a case of isolated SSC, probably of traumatic origin. The existence of this pathological individual among the SH sample represents also a fact to take into account when referring to sociobiological behavior in Middle Pleistocene humans.

Pansynostosis: a review

INTRODUCTION

Although rare, pansynostoses are seen and treated by the craniofacial surgeon. To date, a single source that reviews these more severe forms of craniosynostosis is lacking in the literature.

MATERIALS AND METHODS

The present paper outlines and reviews the associations of both syndromic and nonsyndromic cases, potential mechanisms, and the anatomy involved with such forms of premature fusion of the cranial sutures.

RESULTS

Pansynostosis is seen in a myriad of syndromes but can also be identified in nonsyndromic cases. Raised intracranial pressure is a concern in these patients.

CONCLUSIONS

Early recognition and treatment of patients with pansynostosis of the cranial sutures is important.

Anomalous venous drainage preventing safe posterior fossa decompression in patients with chiari malformation type I and multisutural craniosynostosis. Report of two cases and review of the literature

The authors report on two children in whom an anomalous posterior fossa venous drainage pattern prevented safe posterior fossa decompression. Both patients had Chiari malformation Type I, multisutural craniosynostosis, and crowded posterior fossa structures. Both patients had been treated with ventriculoperitoneal shunts for hydrocephalus. Pfeiffer syndrome had been diagnosed in one of the patients, and the other was suspected to have osteogenesis imperfecta. Although both patients were believed to have symptoms resulting from brainstem compression, posterior fossa decompression was not offered due to profound venous anomalies noted on imaging studies that greatly increased the expected risks associated with surgery. These cases are presented to alert neurosurgeons to carefully evaluate the posterior fossa venous anatomy prior to considering posterior fossa decompression with or without occipitocervical fusion or calvarial vault remodeling procedures in patients with multisutural craniosynostosis.

Morphology and Growth of the Mandible in Crouzon, Apert, and Pfeiffer Syndromes

The purpose of this study was to examine mandibular morphology and growth in patients with Crouzon, Pfeiffer, and Apert syndromes using posteroanterior cephalograms. Fifteen patients with Apert (n = 2), Crouzon (n = 11), and Pfeiffer (n = 2) (11 female, 4 male) syndrome were included in this study. All patients had serial posteroanterior cephalograms at 5, 10, and 15 years of age. The bicondylar width, bigonial width, bicondylar/bigonial ratio, and ramus to intercondylar plane angle for each patient were measured on the cephalograms and compared with age-match controls. An analysis of variance analysis was carried out to detect differences between patients and controls and sex differences between patients. In both male and female patients, there was a statistically significant reduction in bicondylar width compared with age-matched controls. Male patients also had a statistically significant increase in bigonial width compared with controls and female patients at 10 and 15 years. The resulting bicondylar/bigonial ratios were significantly reduced, and the ramus to intercondylar plane angles were significantly increased in both male and female patients compared with controls. Unlike previous reports of patients with syndromic synostosis, this study demonstrates that the mandible has significant morphologic and growth abnormalities, including constriction of bicondylar width with near normal bigonial width in female patients. These findings suggest a narrowing at the cranial base with resulting restriction of normal transverse mandibular growth at the condyle. The secondary nature of the mandibular finding is suggested by the near normal or increased transverse growth at the gonion in females and males, respectively. Consequently, the ramus appears torqued inward, forming a greater angle with the cranial base.

Diagnostic imaging in the management of craniosynostoses

Craniosynostoses are the most frequent craniofacial malformations. However, with a prevalence of 3-6 cases per 10,000 live births they are amongst the rarely seen diseases and their definite diagnosis thus poses a challenge to the physician. When an abnormal calvarial configuration is detected, a radiological evaluation is necessary to characterize the deformity and to guide the corrective surgical procedure. The demand for clear diagnostic criteria is justified by the severity of the disease and the possible consequences of delayed diagnosis. In addition to the clinical signs (deformation of the head), conventional skull X-rays show typical radiological alterations and are used for basic diagnostics. Diagnostic tests that may be performed to confirm the diagnosis and assess the extent of the problem, include computed tomography (CT), 3D-CT, magnetic resonance imaging (MRI) scans, and ultrasonography. In the present review we will describe the most important clinical and radiological characteristics of craniosynostosis by means of clinical, radiological and operative situs examples.

Testing causal mechanisms of nonsyndromic craniosynostosis using path analysis of cranial contents in rabbits with uncorrected craniosynostosis

OBJECTIVE

Various causal mechanisms of familial nonsyndromic craniosynostosis have been presented. One hypothesis suggests that overproduction of bone at the suture is the primary origin of craniosynostosis, which affects brain and cranial growth secondarily through altered intracranial pressure (Primary Suture Fusion Model). Other hypotheses suggest that decreased cranial base growth or abnormal brain growth are the primary cause of craniosynostosis (Cranial Base, Brain Parenchyma Models, respectively). This study was designed to investigate which model best describes neurocranial changes associated with craniosynostosis in a rabbit model through multivariate path analysis.

DESIGN

Serial magnetic resonance imaging scans and intracranial pressure measurements were obtained at 10, 25, and 42 days of age from 18 rabbits: six controls, six with delayed-onset synostosis, and six with early-onset synostosis. Five variables were collected from each rabbit: calvarial thickness at the affected suture, cranial base length, brain volume, cerebrospinal fluid volume, and intracranial pressure. This data set was used to test causal pathway relationships generated by the proposed models. Goodness of fit was measured by experimental group for each model.

RESULTS

Primary Suture Fusion Model best explained the variables in both delayed-onset and early-onset synostotic rabbits (Goodness of fit = 93%, 97%, respectively). Cranial Base Model (Goodness of fit = 94%) best explained the data in control rabbits.

CONCLUSION

Results suggest that the primary site of craniosynostosis in craniosynostotic rabbits is most likely the synostosed suture. Other cranial vault anomalies are most likely secondary compensatory changes. Results of the present study may provide insight regarding the causal pathway of craniosynostosis.

The occurrence of obstructive vs absorptive hydrocephalus in newborns and infants: relevance to treatment choices

BACKGROUND AND OBJECTIVE

The classification of hydrocephalus in newborns and in infants is different from the classification in adulthood. This difference exists due to disparity in the source pathologies that produce the hydrocephalus, and the practical distinctions in prognosis and treatment choices. The objective of this paper is to present the spectrum of obstructive-communicating hydrocephalus, which is more complex in the pediatric group, and to propose the relevance of this particular classification to treatment options.

MATERIALS AND METHODS

The authors categorized infants with active hydrocephalus at time of presentation into the following four groups along the spectrum of communicating vs obstructive HCP. Group 1: patients with a purely absorptive (communicating) HCP. In these patients, tetraventricular dilatation is usually observed with occasional extraaxial fluid accumulation. An extracranial CSF diversion (shunt) is the treatment of choice. Group 2: patients with an obstructive component together with a persistent absorptive component. In these patients, a technically successful endoscopic procedure will not prevent progression of clinical symptoms of HCP. An extracranial CSF diversion (shunt) should be the treatment of choice even though some of these patients are currently treated by endoscopy. Group 3: patients with an obstructive component together with a temporary absorptive component. In these patients, a technically successful ETV should be followed by temporary CSF drainage [via LP, continuous spinal drainage (CLD), or ventriculostomy] with or without supplemental medical treatment (i.e., Diamox) for several days. Such temporary drainage may decrease failure rate in this subgroup. Group 4: patients with a purely obstructive HCP. In these patients, an endoscopic procedure (ETV) is the treatment of choice. According to this spectrum classification, the authors classify different entities with representative cases and discuss relevancy to treatment options and prognosis.

RESULTS

The data suggest that obstructive hydrocephalus in the very young population may be rather a combination of obstructive and absorptive problem. The outcome of the patient depends mainly not only on the basic pathology causing the hydrocephalus but also on the treatment that is chosen and its complications. While bleeding and infection represent the major causes for communicating hydrocephalus, patients with complex pathologies of congenital type and intra- or interventricular obstructions may reflect obstructive hydrocephalus. Treatment of these patients may be successful by shuntless procedures if the absorptive problem is not the major component. In transient absorptive hydrocephalus, temporary measures were effective in many cases leading to successful procedures of ETV and/or posterior-fossa decompression in selected cases.

CONCLUSIONS

Shuntless procedures are the dream of a pediatric neurosurgeon provided it solves the problem and does not imply unacceptable risk. However, the benefit has to be evaluated years after the procedure is performed, as only prospective multicenter studies will truly show which procedure may have the best overall results in the developing child. Until such studies are available, understanding the basic pathology or the combination of pathologies leading to hydrocephalus in a given child may open the window of opportunities for other than shunt surgery in many hydrocephalic children with major obstructive component.

Sporadic congenital hyperthyroidism due to a germline mutation in the thyrotropin receptor gene (Leu 512 Gln) in a Japanese patient

Constitutively activating thyrotropin receptor (TSHR) germline mutations have been identified as a molecular cause of congenital hyperthyroidism. We here describe a Japanese woman who had presented with severe hyperthyroidism and advanced bone age as a neonate. She underwent neurosurgical intervention for craniosynostosis, and presented with perodactylia and mild mental retardation with hydrocephalus. Hyperthyroidism has been refractory to antithyroid drug therapy in the absence of antithyrotropin receptor antibodies during follow-up of 20 years, resulting in an enlarged goiter. Analysis of the patient's genomic DNA showed a heterozygous thymine-to-adenine point mutation in exon 10 of TSHR at position 1535 which was not present in the parents' DNA. This mutation, changing leucine to glutamine in codon 512 in the third transmembrane region, was previously identified as a somatic mutation in toxic thyroid nodules and was shown to increase basal cAMP production in vitro. To our knowledge, this is the first report of a germline mutation of TSHR causing sporadic congenital nonautoimmune hyperthyroidism in a Japanese patient.

Prevalence of Abnormal Pattern Reversal Visual Evoked Potentials in Craniosynostosis

BACKGROUND

The purpose of this study was to examine the prevalence and type of changes observed in the pattern reversal visual evoked potentials recorded at the first assessment of children with craniosynostosis.

METHODS

Visual evoked potentials were recorded from 114 patients with craniosynostosis. Eighty-one patients were syndromic and 33 were nonsyndromic. No patient had received any craniofacial surgical intervention. At the time of the test, 22 of 40 patients were aged 6 months and younger, and 18 patients were between 6 months and 1 year of age. Pattern reversal visual evoked potentials were recorded from a midoccipital electrode positioned 3 cm above the inion. The pattern reversal visual evoked potentials elicited to 50' checks with three reversals per second viewed with both eyes were analyzed for n80-p100 amplitude, p100 latency, and breadth of waveform.

RESULTS

Sixty percent of patients had abnormal pattern reversal visual evoked potentials to 50' checks. This did not show a significant association with age, or classification of craniosynostosis.

CONCLUSIONS

The high prevalence of abnormal pattern reversal visual evoked potentials to a robust stimulus suggests that visual pathway dysfunction, as measured electrophysiologically, can affect a majority of patients with craniosynostosis. This study indicates that a baseline evaluation of all children with craniosynostosis at their first presentation is essential if subsequent electrophysiologic visual pathway monitoring is to take place.

Hydrocephalus in craniosynostosis: a review

INTRODUCTION

Ventricular dilatation in the presence of primary craniosynostosis is a unique condition with respect to pathogenesis, clinical significance, and morphological appearance. It is rarely observed in nonsyndromic craniosynostosis, and in these cases usually attributable to coincidental disorders. Conversely, it is a common feature of syndromic craniosynostosis, affecting at least 40% of patients with Crouzon's, Pfeiffer's or the Apert syndrome. Shunt-dependent hydrocephalus is predominantly associated with Crouzon or Pfeiffer syndrome while in the Apert syndrome the usual finding is nonprogressive ventriculomegaly which, however, may also occur in some cases of Crouzon syndrome.

PATHOGENESIS

The pathogenesis of progressive hydrocephalus remains somewhat obscure, a hypoplastic posterior fossa and a venous outlet occlusion at the skull base being the main causative factors discussed in literature. Ventriculomegaly may reflect primary brain maldevelopment or in some cases even a compensated state of increased cerebrospinal fluid (CSF) outflow resistance. CLINICAL EVALUATION: Clinical evaluation is mainly aimed at identifying progressive hydrocephalus, but diagnosis is hampered by the fact that classical clinical signs may be absent, and that ventricular dilatation will often become evident only after decompressive cranial surgery. Moreover, mild ventriculomegaly may in some cases coexist with intracranial hypertension from craniostenosis. Therefore, careful monitoring of intracranial pressure and ventricular size in the pre- and postoperative period is a diagnostic mainstay.

CONCLUSION

In true hydrocephalus ventriculo-peritoneal shunting is currently the single promising mode of treatment.

Chiari malformation in craniosynostosis

INTRODUCTION

Chiari malformation (CM) is a frequent finding in multisutural and syndromic craniosynostosis, occurring in 70% of patients with Crouzon's syndrome, 75% with oxycephaly, 50% with Pfeiffer's syndrome and 100% with the Kleeblattschädel deformity. The pathogenesis of this condition and rationale for treatment are still controversial.

DISCUSSION

Since its first description in 1972, several factors have been cited to play a role in inducing CM. In the light of recent publications, the roles of premature fusion of cranial vault and cranial base sutures, of congenital anomalies of the cerebellum and brain stem, of raised intracranial pressure, of venous hypertension and of hydrocephalus are reviewed. Evaluation and management of CM are also discussed.

CONCLUSION

Chiari malformation appears to be an acquired and progressive condition that develops in the first months of life, because of a disproportion between hindbrain growth and an abnormally small posterior fossa, a consequence of the premature fusion of lambdoid and cranial base sutures. Venous hypertension caused by stenosis of the jugular foramen can also be present in these patients, resulting in intracranial hypertension and/or hydrocephalus. Careful MRI evaluation is recommended for the forms of craniosynostosis at a high risk of developing hindbrain herniation. The selection of posterior cranial vault expansion as the first surgical procedure is advocated. In selected cases, treatment of the posterior cranial deformity by occipital vault remodelling and treatment of the Chiari-like deformity by suboccipital decompression can be carried out using the same surgical procedure.

Age-related changes in lateral ventricle morphology in craniosynostotic rabbits using magnetic resonance imaging

BACKGROUND AND AIMS

Craniosynostosis occurs in 300-500 per 1,000,000 live births and results in secondary craniofacial, ocular, and intracranial anomalies. Neurologic problems associated with craniosynostosis include changes in intracranial morphology such as dilation of the cerebral ventricles, however, clinical studies are confounded by small sample sizes, heterogenous samples, and lack of age-matched controls. The present study was designed to assess age-related changes in the lateral ventricle volume of the brain in normal rabbits and rabbits with naturally-occurring coronal suture synostosis using serial magnetic resonance imaging.

METHODS

Eighteen rabbits (6 wild-type controls, 6 with early-onset [ approximately 21 days gestation], and 6 with delayed-onset [approximately 25 days post-gestation] coronal suture synostosis) had magnetic resonance imaging (MRI) at 10, 25, and 42 days of age.

RESULTS

The results demonstrate that rabbits with early-onset synostosis had significantly (p<0.001) dilated and larger lateral ventricles (by 77% at 10 days of age) than wild-type and delayed-onset synostosis rabbits, which progressively worsened by day 42.

CONCLUSION

This finding suggests that uncorrected coronal suture synostosis may have early effects on lateral ventricle volume hypertrophy, possibly through obstructed cerebrospinal fluid and/or venous drainage and circulation.

Cranial venous outflow obstruction and pseudotumor Cerebri syndrome

The pathophysiology of PTS including idiopathic intracranial hypertension or 'BIH', remains controversial. The older literature frequently referred to pathology in the cerebral venous drainage but more modern imaging techniques (CT and early MR) failed to reveal gross venous pathology. The role of impaired cranial venous outflow has recently been re-examined in the light of new methods of investigation (advanced MR venography and direct microcatheter venography with manometry) and of treatment (venous sinus stenting). Venous sinus obstruction in PTS is a more common factor in the pathogenesis of the condition than previously recognised. Venous obstruction may be primary, that is, it is the underlying aetiological factor in PTS. Venous sinus obstruction may also be secondary to raised CSF pressure which may exacerbate problems with intracranial compliance and raised CSF pressure. Early experience with venous stenting suggests that it may be a helpful treatment for patients with PTS but more experience and longer follow-up is required to define the subgroups of patients for whom it is most appropriate.

Fetal imaging of central nervous system abnormalities

Fetal MR imaging is complementary to obstetric ultrasonography. The additional information provided by in utero MR imaging may alter prenatal, perinatal, or immediate postnatal management. For example, the MR imaging findings may affect the decision to continue the pregnancy, change the mode, timing, or location of delivery, or modify decisions regarding the necessity of immediate postnatal surgery. Finally, the information contributed by MR may permit a better assessment of the risk of recurrent defects in subsequent pregnancies.

Clinically mild, atypical, and aged craniofacial syndrome is diagnosed as Crouzon syndrome by identification of a point mutation in the fibroblast growth factor receptor 2 gene (FGFR2)

A 53-year-old Japanese woman presented with mild mental retardation, short stature, hypertelorism, saddle nose, vertebral fusion, and hydrocephalus, implying an underlying bone growth impairment mainly of the head and neck. A point mutation in fibroblast growth factor receptor 2 (FGFR2) was identified that had previously been seen only in sporadic cases of Crouzon syndrome. This patient did not exhibit any of the typical features of Crouzon syndrome primarily seen in affected infants, such as a severely deformed skull, an apical shaped skull, or severe mental retardation. The patient was diagnosed with a mild form of Crouzon syndrome. The patient's symptoms very early in life may have been ameliorated and modified through growth and aging. The age-related phenotype modifications in Crouzon syndrome are discussed.

Condition Variables in Children With Craniofacial Anomalies: A Descriptive Study

The objective of the study is to describe the prevalence of a number of condition variables and their interrelations in children with craniofacial anomalies (CFAs). The participants were 217 children with CFAs (125 boys and 92 girls), aged 5 to 16 years. The medical files and brain imaging provided information on most condition variables except for the variable phenotypical expression, on which information was obtained in a rating experiment. Brain anomalies were present in 77 subjects (36%), absent in 79 subjects (36%), and undefined in 61 subjects (28%). Craniosynostosis occurred in 160 children (74%), a syndromic diagnosis in 108 (50%), and clinical hypertelorism in 72 (33%). The mean phenotypical expression score was 4.8 (SD = 2.1), the mean number of hospitalizations was 6.2 (SD = 5.6), and mean age at craniotomy was 10.9 months (SD = 9.3). Many of the condition variables were significantly interrelated. Brain anomalies occur frequently (36%) in syndromic and nonsyndromic forms of CFAs. The most salient condition variables are the presence of brain anomalies, a syndromic diagnosis, clinical hypertelorism, a severe phenotypical expression, and female gender. Individuals presenting with one or more of these condition variables probably form the most severely affected group and require more treatment.

Advances in Craniosynostosis Research and Management

The purpose of the present paper is to analyze the most recent advances in the field of craniosynostosis basic and clinical research and management, and to give an overview of the more frequently adopted surgical strategies. After reviewing some basic concepts regarding normal craniofacial embryology and growth, aetiopathogenesis of craniosynostosis and craniofacial dysostosis, classification and diagnosis and historical evolution of surgical treatment, the authors elaborate on a selection of topics that have modified our current understanding of and therapeutical approach to these disease processes. Areas covered include advances in molecular biology and genetics, imaging techniques and surgical planning, resorbable fixation technology, bone substitutes and tissue engineering, distraction osteogenesis and the spring-mediated cranioplasties, resorbable distractor devices, minimally invasive surgery and in utero surgery. A review of the main subtypes of craniosynostosis and craniofacial dysostosis is presented, including their specific clinical features and a commentary on the presently available surgical options.

The craniofacial surgeon as amateur geneticist

Craniofacial surgeons, by nature and training, focus on how to correct anomalies rather than on why they occur. Surgeons often leave diagnosis and etiopathogenic speculation to geneticists. Craniofacial surgeons should cross over the specialty line and learn to think like geneticists. This article reviews definitions of basic words in the genetic language and emphasizes the three diagnostic levels, phenotypic, pathogenic, and genetic, for the principal categories of craniofacial anomalies. Whenever possible, examples are given to illustrate how genetic knowledge can influence surgical strategy. As a member of the perinatal team, the craniofacial surgeon must be "cyber-savvy" to counsel parents and communicate with geneticists.

New methods for the evaluation and treatment of craniofacial dysostosis-associated cerebellar tonsillar herniation

Herniation of the cerebellar tonsils may occur in children with craniofacial dysostosis (e.g., Apert, Carpenter, Crouzon, Jackson-Weiss, Pfeiffer, and Saethre-Chotzen syndromes), occasionally, with serious sequelae. Cerebellar tonsillar herniation is probably acquired in children affected with craniofacial dysostosis, raising the question, How should we be screening for this anomaly? This retrospective clinical study was undertaken to review the authors' series of what they believe to be a new surgical treatment for craniofacial dysostosis-associated cerebellar tonsillar herniation and to report their experience with a new screening technique. In an attempt to find a low-cost alternative to the use of routine magnetic resonance imaging for identifying cerebellar tonsillar herniation, the authors instituted sagittal reformatting of three-dimensional computed tomographic scans through the foramen magnum. Scans are considered positive if soft tissue is noted to extend below the foramen magnum, and all positive scans are further evaluated by magnetic resonance imaging with flow studies of the cerebrospinal fluid. These sagittally reformatted scans add no additional cost, and they seem to be highly sensitive in screening for cerebellar tonsillar herniation. Over a 13-month period, five children (one with Apert syndrome; four with Crouzon syndrome) with craniofacial dysostosis-associated cerebellar tonsillar herniation underwent isolated anterior cranial vault remodeling to treat observed brachycephaly (standard neurosurgical posterior decompression was not performed). All patients (mean age, 6 years; range, 2 to 14 years) were without the symptoms typically associated with cerebellar tonsillar herniation. Only those patients who had preoperative and postoperative magnetic resonance imaging scans were included in this review. All patients showed some improvement by the authors' magnetic imaging criteria after anterior cranial vault remodeling. Despite these findings, the authors recommend that until the anterior approach can be further studied, symptomatic children should undergo standard posterior neurosurgical decompression. The authors speculate that the presence of cerebellar tonsillar herniation may be a relative indication for decompressing the cranial vault in the craniofacial dysostoses. In addition, they propose that the descriptive anatomic term "cerebellar tonsillar herniation" be substituted for the misnomer "Chiari malformation" in these children.