Consequences of cranial vault expansion surgery for craniosynostosis

Association of cranial base suture/synchondrosis fusion with severity of increased intracranial pressure in Crouzon syndrome

This study investigated how the fusion states of the cranial base is related to the degree of increased intracranial pressure (ICP) in patients with Crouzon syndrome. This retrospective cohort study enrolled patients who were diagnosed with Crouzon syndrome between May 2007 and April 2022. We categorized the patients into three groups: A, B, and C, according to the severity of increased ICP and the number of cranial vault remodeling procedures for corrective operation. The preoperative fusion states of the cranial base sutures/synchondroses were examined using facial bone computed tomography and compared between groups. Overall, 22 patients were included in Groups A, B, and C, including 8, 7, and 7 patients, respectively. The preoperative average grades of the total cranial base suture/synchondrosis fusion appeared to significantly increase with severity, except for the frontoethmoidal suture, which showed the opposite tendency. In the subgroup analysis, frontosphenoidal, sphenoparietal, sphenosquamosal, parietomastoid, and occipitomastoid suture and petro-occipital synchondrosis were associated with earlier fusion in the more severe group. Premature closure of the cranial base sutures/synchodroses seems to be associated with increased ICP severity in patients with Crouzon syndrome. Precise evaluation of minor sutures/synchondroses at the first visit might help build subsequent operative plans and predict disease prognosis.

Comparing the Increased Intracranial Volume From Different Surgical Methods for Syndromic Craniosynostosis

PURPOSE

Fronto-orbital advancement (FOA) is the traditional surgical method used to increase intracranial volume, but posterior cranial vault distraction osteogenesis (PVDO) has been gaining popularity as an initial treatment option. This study aimed to compare the effects of FOA and PVDO on intracranial volume.

PATIENTS AND METHODS

Sixteen patients with multiple-suture synostosis and severe intracranial volume restriction were treated with FOA or PVDO at Children's Hospital of Fudan University between January 2016 and December 2019. Data on age at surgery, sex, preoperative intracranial volume, and postoperative intracranial volume were collected.

RESULTS

Seven patients underwent FOA and 9 underwent PVDO. All patients underwent surgery for the first time, and the surgeries were performed by the same physician. There was no statistically significant difference in age at surgery or in the intracranial volumes before and after surgery between the 2 groups (P>0.05). There was a statistically significant difference in the intracranial volume changes between the 2 groups before and after surgery (P=0.028).

CONCLUSIONS

Posterior cranial vault distraction osteogenesis provided statistically greater intracranial volume expansion than FOA.

Nervous system involvement in Pfeiffer syndrome

Pfeiffer syndrome (PS) is a rare autosomal dominant craniofacial disorder characterized by primary craniosynostosis, midface hypoplasia, and extremities' abnormalities including syndactyly. The purpose of this article was to review the current knowledge regarding how PS affects the nervous system. Methodologically, we conducted a systematic review of the existing literature concerning involvement of the nervous system in PS. Multiple-suture synostosis is common, and it is the premature fusion and abnormal growth of the facial skeleton's bones that cause the characteristic facial features of these patients. Brain abnormalities in PS can be primary or secondary. Primary anomalies are specific developmental brain defects including disorders of the white matter. Secondary anomalies are the result of skull deformity and include intracranial hypertension, hydrocephalus, and Chiari type I malformation. Spinal anomalies in PS patients include fusion of vertebrae, "butterfly" vertebra, and sacrococcygeal extension. Different features have been observed in different types of this syndrome. Cloverleaf skull deformity characterizes PS type II. The main neurological abnormalities are mental retardation, learning difficulties, and seizures. The tricky neurological examination in severely affected patients makes difficult the early diagnosis of neurological and neurosurgical complications. Prenatal diagnosis of PS is possible either molecularly or by sonography, and the differential diagnosis includes other craniosynostosis syndromes. Knowing how PS affects the nervous system is important, not only for understanding its pathogenesis and determining its prognosis but also for the guidance of decision-making in the various critical steps of its management. The latter necessitates an experienced multidisciplinary team.

Hydrocephalus in infants: the unique biomechanics and why they matter

OBJECT

Hydrocephalus diagnosed prenatally or in infancy differs substantially from hydrocephalus that develops later in life. The purpose of this review is to explore hydrocephalus that begins before skull closure and full development of the brain. Understanding the unique biomechanics of hydrocephalus beginning very early in life is essential to explain two poorly understood and controversial issues. The first is why is endoscopic third ventriculostomy (ETV) less likely to be successful in premature babies and in infants? The second relates to shunt failure in a subset of older patients treated in infancy leading to life-threatening intracranial pressure without increase in ventricular volume.

METHODS

The review will utilize engineering concepts related to ventricular volume regulation to explain the unique nature of hydrocephalus developing in the fetus and infant. Based on these concepts, their application to the treatment of complex issues of hydrocephalus management, and a review of the literature, it is possible to assess treatment strategies specific to the infant or former infant with hydrocephalus-related issues throughout life.

RESULTS

Based on engineering, all hydrocephalus, except in choroid plexus tumors or hyperplasia, relates to restriction of the flow of cerebrospinal fluid (CSF). Hydrocephalus develops when there is a pressure difference from the ventricles and a space exterior to the brain. When the intracranial volume is fixed due to a mature skull, that difference is between the ventricle and the cortical subarachnoid space. Due to the distensibility of the skull, hydrocephalus in infants may develop due to failure of the terminal absorption of CSF. The discussion of specific surgical treatments based on biomechanical concepts discussed here has not been specifically validated by prospective trials. The rare nature of the issues discussed and the need to follow the patients for decades make this quite difficult. A prospective registry would be helpful in the validation of surgical recommendations.

CONCLUSION

The time of first intervention for treatment of hydrocephalus is an important part of the history. Treatment strategies should be based on the assessment of the roll of trans-mantle pressure differences in deciding treatment strategies. Following skull closure distension of the ventricles at the time of shunt failure requires a pressure differential between the ventricles and the cortical subarachnoid space.

Improvement in Sleep Architecture is associated with the Indication of Surgery in Syndromic Craniosynostosis

Supplemental Digital Content is available in the text.

Children with syndromic craniosynostosis (sCS) often suffer from obstructive sleep apnea (OSA) and intracranial hypertension (ICH). Both OSA and ICH might disrupt sleep architecture. However, it is unclear how surgically treating OSA or ICH affects sleep architecture. The aim of this study was twofold: to explore the usefulness of sleep architecture analysis in detecting disturbed sleep and to determine whether surgical treatment can improve it.

Intracranial Venous Hypertension in Craniosynostosis: Mechanistic Underpinnings and Therapeutic Implications

Patients with complex, multisutural, and syndromic craniosynostosis (CSO) frequently exhibit intracranial hypertension. The intracranial hypertension cannot be entirely attributed to the craniocephalic disproportion with calvarial restriction because cranial vault expansion has not consistently alleviated elevated intracranial pressure. Evidence has most strongly supported a multifactorial interaction, including venous hypertension along with other pathogenic processes. Patients with CSO exhibit marked venous anomalies, including stenosis of the jugular-sigmoid complex, transverse sinuses, and extensive transosseous venous collaterals. These abnormal intracranial-extracranial occipital venous collaterals might represent anomalous development, with persistence and subsequent enlargement of channels normally present in the fetus, either as a primary defect or as nonregression in response to failure of the development of the jugular-sigmoid complexes. It has been suggested by some investigators that venous hypertension in patients with CSO could be treated directly via jugular foraminoplasty, venous stenting, or jugular venous bypass, although these options are not in common clinical practice. Obstructive sleep apnea, occurring as a consequence of midface hypoplasia, can also contribute to intracranial hypertension in patients with syndromic CSO. Thus, correction of facial deformities, as well as posterior fossa decompression, could also play important roles in the treatment of intracranial hypertension. Determining the precise mechanistic underpinnings underlying intracranial hypertension in any given patient with CSO requires individualized evaluation and management.

Chronic Debilitating Headache in Adults Caused by Craniocerebral Disproportion: Treatment by Cranial Vault Expansion

Craniocerebral disproportion is rarely considered as a cause for chronic, debilitating headache in adults. Children reported with this disorder typically suffer from headaches and lethargy for many years and have multisutural synostosis. The terms craniocerebral disproportion, craniostenosis, and slit-ventricle syndrome are used inconsistently as diagnostic designations. Three adults with craniocerebral disproportion who had been treated in infancy for two different pathologies are reported. All benefited greatly from cranial vault expansion.

Raised intracranial pressure in Crouzon syndrome: incidence, causes, and management

OBJECT Patients with Crouzon syndrome (CS) are at risk for developing raised intracranial pressure (ICP), which has the potential to impair both vision and neurocognitive development. For this reason, some experts recommend early prophylactic cranial vault expansion on the basis that if ICP is not currently raised, it is likely to become so. The aim of this study was to examine the justification for such a policy. This was done by analyzing the incidence, causes, and subsequent risk of recurrence in a series of patients with CS, in whom raised ICP was treated only after it had been diagnosed. METHODS This study was a retrospective review of the medical records and imaging data of patients with a clinical diagnosis of CS. RESULTS There were 49 patients in the study, of whom 30 (61.2%) developed at least 1 episode of raised ICP. First episodes occurred at an average age of 1.42 years and were attributable to craniocerebral disproportion/venous hypertension (19 patients), hydrocephalus (8 patients), and airway obstruction (3 patients). They were managed, respectively, by vault expansion, ventriculoperitoneal shunt insertion, and airway improvement. Fourteen of the 30 patients developed a second episode of raised ICP an average of 1.42 years after treatment for their initial episode, and 3 patients developed a third episode an average of 3.15 years after that. Causes of subsequent episodes of raised ICP often differed from previous episodes and required different management. Patients who were < 1 year old when the first episode was diagnosed were at increased risk of recurrence. CONCLUSIONS Although the incidence of raised ICP in CS is high, it did not occur in nearly 40% of children during the course of this study. The several possible causes of CS require different management and may vary from episode to episode. The authors recommend an expectant policy toward these children with careful clinical, ophthalmological, respiratory, and radiological monitoring for raised ICP, reserving intervention for when it has been detected and the appropriate treatment can be initiated.

Apert and Crouzon syndromes-Cognitive development, brain abnormalities, and molecular aspects

Apert and Crouzon are the most common craniosynostosis syndromes associated with mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. We conducted a study to examine the molecular biology, brain abnormalities, and cognitive development of individuals with these syndromes. A retrospective longitudinal review of 14 patients with Apert and Crouzon syndromes seen at the outpatient Craniofacial Surgery Hospital for Rehabilitation of Craniofacial Anomalies in Brazil from January 1999 through August 2010 was performed. Patients between 11 and 36 years of age (mean 18.29 ± 5.80), received cognitive evaluations, cerebral magnetic resonance imaging, and molecular DNA analyses. Eight patients with Apert syndrome (AS) had full scale intelligence quotients (FSIQs) that ranged from 47 to 108 (mean 76.9 ± 20.2), and structural brain abnormalities were identified in five of eight patients. Six patients presented with a gain-of-function mutation (p.Ser252Trp) in FGFR2 and FSIQs in those patients ranged from 47 to78 (mean 67.2 ± 10.7). One patient with a gain-of-function mutation (p.Pro253Arg) had a FSIQ of 108 and another patient with an atypical splice mutation (940-2A →G) had a FSIQ of 104. Six patients with Crouzon syndrome had with mutations in exons IIIa and IIIc of FGFR2 and their FSIQs ranged from 82 to 102 (mean 93.5 ± 6.7). These reveal that molecular aspects are another factor that can be considered in studies of global and cognitive development of patients with Apert and Crouzon syndrome (CS). © 2016 Wiley Periodicals, Inc.

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.

Craniofacial reconstruction as a treatment for elevated intracranial pressure

INTRODUCTION

Craniofacial procedures may be needed to address symptomatic intracranial hypertension. The authors review their institutional experience in the treatment of children with symptomatic increased intracranial pressure (ICP) utilizing craniofacial reconstructive procedures.

METHODS

The senior authors' (HSM, SRC) craniofacial experience of 222 patients over a 7-year period from 2000 to 2007 at a single institution (Rady Children's Hospital, San Diego) is reviewed. Seventeen patients were identified who were felt to be candidates for craniofacial surgery with symptomatic increased ICP.

RESULTS

Patient diagnoses included single-suture craniosynostosis, craniofacial dysostoses, shunt-induced craniostenosis, and shunt-associated intracranial hypertension (slit-ventricle syndrome). Seventeen patients underwent 21 craniofacial procedures. Age at surgery ranged from 3 months to 13 years with a mean of 5 years. Preoperative symptoms and signs included headaches, unexplained irritability, seizures, papilledema, and visual loss. All patients had diagnostic neuroimaging. Seven patients had preoperative invasive ICP measurements. Surgery was deferred on three of these patients based on these measurements. The mean total operative (including anesthetic preparation) and surgical times were 3 h 12 min and 2 h 20 min, respectively. Percentage operative blood loss averaged 11.3%. In six procedures, no transfusions were required. Average hospital stay was 4 days. There was no perioperative mortality or significant surgery associated morbidity. All patients have had postoperative clinical improvement in signs and symptoms of increased ICP.

CONCLUSIONS

Using modern diagnostic and surgical techniques, including invasive ICP monitoring, increased intracranial pressure can be successfully managed by an experienced, multidisciplinary, craniofacial team. Our treatment paradigm and operative management scheme is discussed.

Resolution of syndromic craniosynostosis-associated Chiari malformation Type I without suboccipital decompression after posterior cranial vault release

Chiari malformation Type I (CM-I) is associated with syndromic and nonsyndromic craniosynostosis in pediatric patients, and the surgical management of CM-I in such cases is controversial. Previous guidelines have recommended simultaneous cranial vault expansion and suboccipital decompression. However, spontaneous resolution of CM-I has been observed, and the combined procedure carries additional surgical risks. The authors report the case of a 6-month-old boy with Crouzon syndrome, CM-I, and a cervical syrinx who underwent posterior cranial vault release without suboccipital decompression. Imaging at the 3-month follow-up visit demonstrated complete resolution of the CM-I, improvement in CSF flow, and reduction in the size of the syrinx. This case suggests that up-front suboccipital decompression may not be necessary in patients with craniosynostosis and CM-I. A strategy of initial cranial vault release, followed by watchful waiting and radiographic surveillance, is proposed.

Occipital expansion without osteotomies in Apert syndrome

INTRODUCTION

Cranial expansion has been the mainstay of initial management of children with Apert syndrome. Surgical timing is a balance between the risk of relapse if performed too early and the possibility of raised intracranial pressure and ossification defects if performed later. Primary occipital expansion has been proposed as a method to delay the timing of frontal surgery. We have applied the principal of spring expansion of patent sutures to expand the posterior cranial fossa without a cranial osteotomy.

PATIENTS AND METHODS

All new Apert syndrome patients seen during the 3-year period December 2004-December 2007 underwent initial occipital expansion without osteotomy using spring expansion of the patent lambdoid suture.

RESULTS

Four new Apert syndrome patients underwent posterior spring expansion of the patent lambdoid suture. Good occipital expansion was achieved in all cases. Standard frontal advancement was performed 5-18 months later. No relapse after frontal advancement has been seen after mean follow-up of 41 months.

CONCLUSIONS

Spring expansion of the patent lambdoid suture is an alternative technique to expand the posterior cranial fossa. Compared to current techniques it has very low morbidity. Occipital expansion is thought to treat several of the mechanisms responsible for raised intracranial pressure in Apert syndrome. When performed at 6 months of age it has enabled us to delay the time at which we would normally perform frontal advancement surgery until a time when the surgical result is likely to be more stable.

Increased Frequency of Left-Handedness in Patients with Unilateral Coronal Synostosis

Objective:

Left-handedness reportedly has been more common in persons with neurological afflictions (e.g., stroke) and malformations (e.g., cleft lip with or without cleft palate) that demonstrate marked unilateral involvement. Coronal synostosis is also more frequently unilateral, affecting the right side more commonly than the left. We sought to compare left-handedness in patients with unilateral coronal synostosis versus healthy controls.

Subjects:

All patients aged 3 years or older with nonsyndromic unilateral coronal synostosis and healthy controls recruited by pediatricians blinded to the study.

Main Outcome Measures:

Prospective data obtained for all participants included age, gender, and handedness. In patients with unilateral coronal synostosis, the side of synostosis and age at surgery were documented. Left-handedness in the study and control groups was compared using chi-square analysis. Left-handedness also was analyzed in the study group according to side of fusion.

Results:

Eighty-six patients with nonsyndromic unilateral coronal synostosis comprised the study group; there were 96 controls. The mean ages of the study (8.8 years) and control groups (9.8 years) were not statistically different (p > .05). There were more girls in the study group (67%) than in the control group (56%), but this difference was not statistically significant (p > .05). Left-handedness was documented in 30.2% of the study group and 11.4% of the control group (p < .005). Left-handedness was twice as common in patients with left versus right unilateral coronal synostosis (44.4% versus 20.4%; p < .05).

Conclusions:

Left-handedness is nearly three times more common in patients with unilateral coronal synostosis than in controls and four times more likely in patients with left-sided fusion.

Implications of a vertex bulge following modified strip craniectomy for sagittal synostosis

BACKGROUND

Modified strip craniectomy is a common treatment for early isolated sagittal synostosis. The authors assessed the significance of the development of a progressive vertex bulge following strip craniectomy as a predictor of raised intracranial pressure or multiple suture synostosis.

METHODS

All cases of sagittal synostosis treated by modified strip craniectomy (removal of the sagittal suture with lateral barrel staving) at the authors' institution were reviewed. Eighty-nine patients with isolated sagittal synostosis were treated by modified strip craniectomy, usually before 6 months of age, between 1995 and 2005. Seven patients were noted to have developed a progressive vertex bulge. The vertex bulge was noted an average of 8 months postoperatively (range, 2 to 25 months). The clinical records of these seven patients were evaluated with regard to their clinical course, radiologic investigations, genetics testing, intracranial pressure monitoring, and the need for further surgery.

RESULTS

Computed tomographic scanning demonstrated new synostosis involving other calvarial sutures in five patients. Five patients underwent intracranial pressure monitoring, and this was elevated in four patients. One patient required a ventriculoperitoneal shunt for hydrocephalus. All patients underwent genetic screening, and two were found to have fibroblast growth factor receptor (FGFR) mutations (one FGFR2 and one FGFR3 mutation). All patients required reoperation (calvarial remodeling) for either raised intracranial pressure, deteriorating head shape, or both.

CONCLUSIONS

A progressive vertex bulge after modified strip craniectomy is a sign of possible raised intracranial pressure, the development of progressive multiple suture synostosis, or both. It is an indication for genetic testing for FGFR mutations.

Intracranial pressure monitoring in children with single suture and complex craniosynostosis: a review

INTRODUCTION

One third of patients with craniofacial dysostosis syndromes and about 15-20% of children with single suture craniostenosis have a documented increase in intracranial pressure (ICP). The early detection of intracranial hypertension is important in order to reduce the risks for brain development and visual function. However, in children with craniosynostosis, the clinical manifestations of abnormally increased ICP are difficult to detect, as the majority of patients may have neither warning signs nor symptoms for a long period of time.

REVIEW

Moreover, data from the literature suggest that neither fundoscopic nor radiological findings are necessarily related to intracranial pressure recordings in this type of pathology. In this context prolonged ICP monitoring seems actually to be the most valuable diagnostic tool. Extradural, subdural, and intraparenchymal devices have been used, and different softwares have been employed for PC storage and analysis of the data obtained. Most recent series consider mean ICP combined with plateaux waves as the most sensitive indicators in the final evaluation of the results.

CONCLUSIONS

The analysis of the literature demonstrates a significant difference in the prevalence of raised ICP preoperatively between non-syndromic and syndromic patients. Among the non-syndromic children, a direct relation between the number of sutures involved and raised ICP is documented. The analysis of plateaux waves seems to be particularly important in children with borderline mean ICP values. Persistent postoperative raised ICP has been described in 6-15% of patients with craniofacial dysostosis. It must be related to the multifactorial etiology of increased ICP in these patients, which includes cerebral venous congestion, upper airway obstruction, and hydrocephalus.

Skull vault growth in craniosynostosis

BACKGROUND

Since its first description by Virchow, the principle of abnormal skull growth due to restriction of skull growth at the fused sutures, and the realisation by Moss that the sutures at the skull base are equally affected, have been the main intellectual driving forces behind the majority of cranial expansion procedures performed currently in children with craniosynostosis.

CURRENT OBSERVATIONS

Despite original impressions that craniosynostosis leads to craniostenosis, many studies have demonstrated that in the majority of patients with craniosynostosis there is normal skull volume in those over the age of 6 months. In Apert syndrome, skull volume is invariably larger than normal. Some studies have shown that intracranial pressure is independent of intracranial volume, and can exist in the presence of normal volume, or indeed after cranial expansion. These observations imply that cranial expansion procedures create a state of artificially increased skull volume, in the quest to improve appearance and function.

FUTURE ADVANCES

This creates a new angle of view through which skull growth abnormalities are seen. It is becoming clearer that in most patients with craniosynostosis, there is regional imbalance of skull growth, which co-exists with a variety of other equally important factors, such as genetic defects, raised intracranial pressure, venous hypertension, and other brain parenchymal anomalies such as hindbrain hernia or hydrocephalus. It is becoming increasingly obvious that the type of surgical treatment currently practised in most cases is conceptually incorrect. Recent modifications such as the use of springs or distraction do not escape from the underlying philosophy of cranial expansion. With that in mind, it is hoped that advances in the fields of genetics and molecular biology will provide treatments for the cause of craniosynostosis rather than the symptomatic relief that surgery offers currently.

CONCLUSION

Until then, there is a need to develop better ways of quantifying regional abnormalities of skull growth.

Skull base growth in craniosynostosis

INTRODUCTION

The interrelationship of skull base growth and craniosynostosis is one that is not often taken into account in the clinical management of patients with craniofacial disorders by neurosurgeons and craniofacial surgeons. Very early on in our medical training we are taught the anatomical differences between the calvarial unit and skull base portion of the skull. The inherent differences in both underlying tissue components and the different growth characteristics of these two uniquely different structures are critical in understanding skull base growth in craniosynostosis and the inherent potential craniofacial growth in these unique children.

REVIEW

This paper will review some of the basic anatomy of these zones of growth plus review some of the prevalent theories of the effect of skull base growth on craniosynostosis and the converse.

CONCLUSION

While the theories of these growth patterns have yet to be finalized an understanding of their potential influences and abnormal growth patterns remain key to providing a good surgical outcome in surgery for craniosynostosis.

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.

Venous hypertension and craniosynostosis

INTRODUCTION

This article addresses the relevance of venous hypertension to children born with, in particular, the "syndromic" forms of craniosynostosis. The development of the human cerebral venous system is summarised and the patterns of anomalous venous drainage seen in children with complex forms of craniosynostosis associated with raised intracranial pressure are described.

AETIOLOGY

The aetiology of these abnormal patterns is discussed under the general headings of "The constriction theory", "A primary role for FGFR mutations" and "Persistence of the foetal pattern of intracranial venous drainage."Venous hypertension (along with hydrocephalus, cranio-cerebral disproportion and airway obstruction) has an important role in the aetiology of raised intracranial pressure in severely affected children.

TREATMENT

The inter-relationship between these factors is explained and then the treatment of those children whose raised intracranial pressure is considered to be due predominantly to venous hypertension is described.

FGFR3 P250R mutation increases the risk of reoperation in apparent 'nonsyndromic' coronal craniosynostosis

Many patients with a clinical diagnosis of "nonsyndromic" coronal craniosynostosis have been found to be heterozygous for the fibroblast growth factor receptor 3 (FGFR3) mutation Pro250Arg. The phenotype associated with this mutation is variable and lacks highly distinctive features, so it is difficult to diagnose on clinical examination alone. The authors present a retrospective study of 76 patients with isolated coronal synostosis who were operated on in a single dedicated craniofacial unit over 25 years. The authors investigated whether any single factor, including the presence of a FGFR3 Pro250Arg mutation, predisposed to an increased transcranial reoperation rate. Eight patients had repeat transcranial surgery for a functional indication. Heterozygosity for the FGFR3 Pro250Arg mutation, present in 29 patients in the cohort, was the only factor found to have a significant association (P=0.048) with the transcranial reoperation rate. Six patients (20.7%) with the mutation underwent reoperation on the basis of raised intracranial pressure, as compared with two patients (4.3%) without the mutation. This highlights the need for genetic analysis and long-term clinical follow-up in apparently "isolated" coronal synostosis.

Craniofacial surgery: complications and their prevention

This article focuses on the management of perioperative complications in surgery dealing with structures of the craniofacial complex. A brief review of applicable surgical techniques is given, beginning with single-suture craniosynostoses and moving on to the more complex syndromic craniofacial disorders. Distinctive complications associated with each technique are discussed.

Enigma of raised intracranial pressure in patients with complex craniosynostosis: the role of abnormal intracranial venous drainage

OBJECT

In this study the authors investigated whether patterns of intracranial venous drainage in children with complex craniosynostosis associated with raised intracranial pressure (ICP) were abnormal and, thus, could support the theory that venous hypertension is a major contributor to raised ICP that can lead to impaired visual function or even blindness in these patients.

METHODS

The authors analyzed the anatomy of intracranial venous drainage as demonstrated in the results of 24 angiography studies obtained in 23 patients, all of whom had either a craniosynostosis-related syndrome (18 patients) or a nonsyndromic multisutural synostosis (five patients). Twenty-one patients had experienced raised ICP (in 19 patients diagnosis was based on invasive ICP monitoring and in two patients on clinical grounds alone) 1 to 6 weeks before undergoing angiography. Of the two remaining patients (both with Apert syndrome) whose ICP monitoring was normal immediately before angiography, each had undergone two previous cranial vault expansion procedures. On results of 18 angiography studies a 51 to 99% stenosis or no flow at all could be observed in the sigmoid-jugular sinus complex either bilaterally (11 patients) or unilaterally (seven patients). In 11 of these patients a florid collateral circulation through the stylomastoid emissary venous plexus was also seen. Two angiography studies were performed in one patient with Crouzon syndrome. A comparison of the two studies demonstrated a progression of the abnormal venous anatomy in that case. The authors found no obvious correlation between each patient's baseline ICP and the degree of abnormality of their venous anatomy, as judged on the basis of a venous-phase angiography severity score.

CONCLUSIONS

Based on their findings, the authors assert that in children with complex forms of craniosynostosis in whom other factors, such as hydrocephalus, are absent, abnormalities of venous drainage that particularly affect the sigmoid-jugular sinus complex produce a state of venous hypertension that, in turn, is responsible for the majority of cases of raised ICP. The incidence of these changes is unknown, but an analysis of the ages of the children in this study indicated that the period of particular vulnerability to the effects of venous hypertension lasts until the affected child is approximately 6 years old. After that age the collateral venous drainage through the stylomastoid plexus will likely become sufficient to allow ICP to normalize.