MR venography in children with complex craniosynostosis

What We Know About Intracranial Hypertension in Children With Syndromic Craniosynostosis

OBJECTIVE

A scoping review of literature about mechanisms leading to intracranial hypertension (ICH) in syndromic craniosynostosis (sCS) patients, followed by a narrative synopsis of whether cognitive and behavioral outcome in sCS is more related to genetic origins, rather than the result of ICH.

METHODS

The scoping review comprised of a search of keywords in EMBASE, MEDLINE, Web of science, Cochrane Central Register of Trials, and Google scholar databases. Abstracts were read and clinical articles were selected for full-text review and data were extracted using a structured template. A priori, the authors planned to analyze mechanistic questions about ICH in sCS by focusing on 2 key aspects, including (1) the criteria for determining ICH and (2) the role of component factors in the Monro-Kellie hypothesis/doctrine leading to ICH, that is, cerebral blood volume, cerebrospinal fluid (CSF), and the intracranial volume.

RESULTS

Of 1893 search results, 90 full-text articles met criteria for further analysis. (1) Invasive intracranial pressure measurements are the gold standard for determining ICH. Of noninvasive alternatives to determine ICH, ophthalmologic ones like fundoscopy and retinal thickness scans are the most researched. (2) The narrative review shows how the findings relate to ICH using the Monro-Kellie doctrine.

CONCLUSIONS

Development of ICH is influenced by different aspects of sCS: deflection of skull growth, obstructive sleep apnea, venous hypertension, obstruction of CSF flow, and possibly reduced CSF absorption. Problems in cognition and behavior are more likely because of genetic origin. Cortical thinning and problems in visual function are likely the result of ICH.

Craniovascular variation in four late Holocene human samples from southern South America

Craniovascular traits in the endocranium (traces of middle meningeal vessels and dural venous sinuses, emissary foramina) provide evidence of vascular anatomy in osteological samples. We investigate the craniovascular variation in four South American samples and the effect of artificial cranial modifications (ACM). CT scans of human adult crania from four archeological samples from southern South America (including skulls with ACM) are used for the analyses. The craniovascular features in the four samples are described, skulls with and without ACM are compared, and additionally, South Americans are compared to a previously analyzed sample of Europeans. Of the four South American samples, the Southern Patagonian differs the most, showing the most distinct cranial dimensions, no ACM, and larger diameters of the emissary foramina. Unlike previous studies, we did not find any major differences in craniovascular features between modified and non-modified skulls, except that the skulls with ACM present somewhat smaller foramina. South Americans significantly differed from Europeans, especially in the anteroposterior dominance of the middle meningeal artery, in the pattern of sinus confluence, in the occurrence of enlarged occipito-marginal sinuses, and in foramina frequencies and diameters. Craniovascular morphology is not affected by the cranial size, even in skulls with ACM, indicating a minor or null influence of structural topological factors. Concerning the samples from distinct geographic and climatic environments, it must be evaluated whether the craniovascular morphogenesis might be partially influenced by specific functions possibly associated with thermoregulation, intracranial pressure, and the maintenance of intracranial homeostasis.

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).

Diploic vein morphology in normal and craniosynostotic adult human skulls

Diploic veins (DV) run within the cranial diploe, where they leave channels that can be studied in osteological samples. This study investigates overall DV variability in human adults and the effects of sex, age, cranial dimensions, and dysmorphogenesis associated with craniosynostosis (CS). The morphology of macroscopic diploic channels was analyzed in a set of the qualitative and quantitative variables in computed tomography-images of crania of anatomically normal and craniosynostotic adult individuals. Macroscopic diploic channels occur most frequently in the frontal and parietal bones, often with a bilaterally symmetrical pattern. DV-features (especially DV-pattern) are characterized by high individual diversity. On average, there are 5.4 ± 3.5 large macroscopic channels (with diameters >1 mm) per individual, with a mean diameter of 1.7 ± 0.4 mm. Age and sex have minor effects on DV, and cranial proportions significantly influence DV only in CS skulls. CS is associated with changes in the DV numbers, distributions, and diameters. Craniosynostotic skulls, especially brachycephalic skulls, generally present smaller DV diameters, and dolichocephalic skulls display increased number of frontal DV. CS, associated with altered cranial dimensions, suture imbalance, increased intracranial pressure, and with changes of the endocranial craniovascular system, significantly also affects the macroscopic morphology of DV in adults, in terms of both structural (topological redistribution) and functional factors. The research on craniovascular morphology and CS may be of interest in biological anthropology, paleopathology, medicine (e.g., surgical planning), but also in zoology and paleontology.

Changes in venous drainage after posterior cranial vault distraction and foramen magnum decompression in syndromic craniosynostosis

OBJECTIVE

The authors' objective was to measure the effect of posterior cranial vault distraction (PCVD) plus foramen magnum decompression (FMD) on dural sinus volume and venous flow in patients with syndromic craniosynostosis.

METHODS

The volumes of the sagittal, straight, transverse, and sigmoid sinuses of 5 consecutive patients with syndromic craniosynostosis who underwent PCVD+FMD were calculated in cubic centimeters with T2-weighted volumetric MRI sequences before surgery, immediately after surgery, and after the end of the distraction process. Tridimensional reconstructions of phase-contrast magnetic resonance angiography (PC-MRA) images were obtained with multiplanar reconstruction (MPR).

RESULTS

The average total volume of all dural sinuses increased immediately after surgery (from 10.06 cm3 to 12.64 cm3) and continued to increase throughout the 30-day distraction period (from 12.64 cm3 to 14.71 cm3) (p = 0.04), except that the right sigmoid sinus remained stable after the initial increase. The most important increases were observed for the left transverse sinus (+113.2%), right transverse sinus (+104.3%), left sigmoid sinus (+91.3%), and sagittal sinus (+41.8%). Less important modifications were evident for the right sigmoid sinus (+33.7%) and straight sinus (+23.4%). Significant improvements in venous flow were noted on the tridimensional reconstructions of the PC-MRA images. Venous obstruction grading score improved in 4 patients (average [range] 2.4 [ 2-5]) (p = 0.023) and remained stable in 1 patient. All patients had chronic tonsillar herniation (CTH) (mean [range] 16.6 [8-26] mm), and 3 had syringomyelia. CTH showed improvement on the last follow-up MRI evaluation in 4 patients (mean [range] 10.5 [0-25] mm) and worsened from 15 mm to 19 mm in 1 patient. Syringomyelia improved in 2 patients and remained unchanged in 1.

CONCLUSIONS

This study has provided the first radiological evidence of the impact of craniofacial surgery on dural sinus anatomy and venous drainage. The venous anomalies described in patients with syndromic craniosynostosis are not static, and PCVD+FMD triggers a dynamic process that can lead to significant modifications of intracranial venous drainage. The traction exerted by the distracted bone flap onto the occipitoparietal dura mater adherent to the inner calvaria may account for the enlargement of the dural sinus throughout the distraction period. The impact of these modifications on venous pressure, intracranial pressure, CTH, and hydrocephalus remains to be determined.

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

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

Craniovascular traits and braincase morphology in craniosynostotic human skulls

Middle meningeal vessels, dural venous sinuses, and emissary veins leave imprints and canals in the endocranium, and thus provide evidence of vascular patterns in osteological samples. This paper investigates whether craniovascular morphology undergoes changes in craniosynostotic human skulls, and if specific alterations may reflect structural and functional relationships in the cranium. The analyzed osteological sample consists of adult individuals with craniosynostoses generally associated with dolichocephalic or brachycephalic proportions, and a control sample of anatomically normal adult skulls. The pattern and dominance of the middle meningeal artery, the morphology of the confluence of the sinuses, and the size and number of the emissary foramina were evaluated. Craniovascular morphology was more diverse in craniosynostotic skulls than in anatomically normal skulls. The craniosynostotic skulls often displayed enlarged occipito-marginal sinuses and more numerous emissary foramina. The craniosynostotic skulls associated with more brachycephalic morphology often presented enlarged emissary foramina, while the craniosynostotic skulls associated with dolichocephalic effects frequently displayed more developed posterior branches of the middle meningeal artery. The course and morphology of the middle meningeal vessels, dural venous sinuses, and emissary veins in craniosynostotic skulls can be related to the redistribution of growth forces, higher intracranial pressure, venous hypertension, or thermal constraints. These functional and structural changes are of interest in both anthropology and medicine, involving epigenetic traits that concern the functional and ontogenetic balance between soft and hard tissues.

Venous anomalies in hypoplastic posterior fossa: unsolved questions

INTRODUCTION

Anomalous intracranial venous anatomy is described in patients with syndromic craniosynostosis and is of significant importance when it comes to surgical morbidity. However, it is still controversial its origin, type of circulation in each syndrome, how it behaves over time, when it can be interrupted and wether it needs to be studied. The purpose of this paper is to discuss these issues by reviewing the literature.

METHODS

A literature search was performed using the PubMed database with a focus on papers including detailed descriptions of the venous outflow in complex and syndromic craniosynostosis. Search details used were the following: ("veins"[MeSH Terms] OR "veins"[All Fields] OR "venous"[All Fields]) AND ("abnormalities"[Subheading] OR "abnormalities"[All Fields] OR "anomalies"[All Fields]) AND syndromic[All Fields] AND ("craniosynostoses" [MeSH Terms] OR "craniosynostoses"[All Fields] OR "craniosynostosis"[All Fields]). Studies that exposed details of venous anomalies found in syndromic or complex craniosynostosis were selected.

RESULTS

Of a total of 211 articles found, 11 were selected for this review. Of these, 5 were case reports, 5 retrospective studies, and only 1 prospective study. From the 6 series of cases presented, 5 discussed the relationship between jugular foramen stenosis (JFS) and collateral venous drainage. The authors discuss data from the literature for each leading question presented: 1-collateral circulation: is it an intrinsic trouble, a consequence of stenosis of the cranial base foramina or related to raised intracranial pressure (ICP)?; 2-what venous anomalies should we search for, and what is the best exam to study them?; 3-collateral circulation changes with time?; 4-can neurosurgeons interrupt the collateral circulation?; 5-should we study all complex types of craniosynostosis?

CONCLUSION

The importance of the study of the venous outflow in patients with complex craniosynostosis is evident in the literature. The real relationship between intracranial hypertension, hypoplastic skull base foramen, Chiari I malformation, hydrocephalus, and venous collateral circulation remains unknown. Prospective studies focusing on molecular biology analysis will possibly solve all of these leading questions.

Saethre-Chotzen syndrome: long-term outcome of a syndrome-specific management protocol

AIM

To assess the long-term outcomes of our management protocol for Saethre-Chotzen syndrome, which includes one-stage fronto-orbital advancement.

METHOD

All patients born with Saethre-Chotzen syndrome between January 1992 and March 2017 were included. Evaluated parameters included occipital frontal head circumference (OFC), fundoscopy, neuroimaging (ventricular size, tonsillar position, and the presence of collaterals/an abnormal transverse sinus), polysomnography, and ophthalmological outcomes. The relationship between papilledema and its associated risk factors was evaluated with Fisher's exact test.

RESULTS

Thirty-two patients (21 females, 11 males) were included. Median (SD) age at first surgery was 9.6 months (3.1mo) for patients who were primarily referred to our center (range: 3.6-13.0mo), the median (SD) age at last follow-up was 13 years (5y 7mo; range: 3-25y). Seven patients had papilledema preoperatively, which recurred in two. Two patients had papilledema solely after first surgery. Second cranial vault expansion was indicated in 20%. Thirteen patients had an OFC deflection, indicating restricted skull growth, one patient had ventriculomegaly, and none developed hydrocephalus. Eleven patients had emissary veins, while the transverse sinus was aberrant unilaterally in 13 (hypoplastic n=10 and absent n=3). Four patients had mild tonsillar descent, one of which was a Chiari type I malformation. Four patients had obstructive sleep apnoea (two mild, one moderate, and one severe). An aberrant transverse sinus was associated with papilledema (p=0.01).

INTERPRETATION

Single one-stage fronto-orbital advancement was sufficient to prevent intracranial hypertension for 80% of our patients with Saethre-Chotzen syndrome. Follow-up should focus on OFC deflection and venous anomalies.

Venous pathologies in paediatric neuroradiology: from foetal to adolescent life

The interpretation of cerebral venous pathologies in paediatric practice is challenging as there are several normal anatomical variants, and the pathologies are diverse, involving the venous system through direct and indirect mechanisms. This paper aims to provide a comprehensive review of these entities, as their awareness can avoid potential diagnostic pitfalls. We also propose a practical classification system of paediatric cerebral venous pathologies, which will enable more accurate reporting of the neuroimaging findings, as relevant to the underlying pathogenesis of these conditions. The proposed classification system comprises of the following main groups: arterio-venous shunting-related disorders, primary venous malformations and veno-occlusive disorders. A multimodal imaging approach has been included in the relevant subsections, with a brief overview of the modality-specific pitfalls that can also limit interpretation of the neuroimaging. The article also summarises the current literature and international practices in terms of management options and outcomes in specific disease entities.

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.

The influence of suturectomy on age-related changes in cerebral blood flow in rabbits with familial bicoronal suture craniosynostosis: A quantitative analysis

Background

Coronal suture synostosis is a condition which can have deleterious physical and cognitive sequelae in humans if not corrected. A well-established animal model has previously demonstrated disruptions in intracranial pressure and developmental abnormalities in rabbits with congenital craniosynostosis compared to wild type rabbits.

Objective

The current study aimed to measure the cerebral blood flow (CBF) in developing rabbits with craniosynostosis who underwent suturectomy compared to those with no intervention and compared to wild type rabbits.

Methods

Rabbits with early onset coronal suture synostosis were assigned to have suturectomy at 10 days of age (EOCS-SU, n = 15) or no intervention (EOCS, n = 18). A subset of each group was randomly selected for measurement at 10 days of age, 25 days of age, and 42 days of age. Wild type rabbits (WT, n = 18) were also randomly assigned to measurement at each time point as controls. Cerebral blood flow at the bilateral hemispheres, cortices, thalami, and superficial cortices was measured in each group using arterial spin-labeling MRI.

Results

At 25 days of age, CBF at the superficial cortex was significantly higher in EOCS rabbits (192.6 ± 10.1 mL/100 mg/min on the left and 195 ± 9.5 mL/100 mg/min on the right) compared to WT rabbits (99.2 ± 29.1 mL/100 mg/min on the left and 96.2 ± 21.4 mL/100 mg/min on the right), but there was no significant difference in CBF between EOCS-SU (97.6 ± 11.3 mL/100 mg/min on the left and 99 ± 7.4 mL/100 mg/min on the right) and WT rabbits. By 42 days of age the CBF in EOCS rabbits was not significantly different than that of WT rabbits.

Conclusion

Suturectomy eliminated the abnormally increased CBF at the superficial cortex seen in EOCS rabbits at 25 days of age. This finding contributes to the evidence that suturectomy limits abnormalities of ICP and CBF associated with craniosynostosis.

Clinical Significance of Venous Anomalies in Syndromic Craniosynostosis

Background

The pattern of cranial venous drainage in syndromic craniosynostosis is unpredictable and not adequately understood. Collateral channels substitute for stenotic venous sinuses and pose potential risk for surgical intervention. The purpose of this study was to analyze the patterns of venous drainage in patients with syndromic craniosynostosis and their influence on operative planning and morbidity.

Methods

A retrospective study of patients with syndromic craniosynostosis from 2000 to 2013 was performed. Demographic data were collected including phenotype and associated pathologies. Pre- and/or postoperative venous imaging was reviewed for venous sinus stenosis, collateral emissaries, and persistent fetal sinuses. Categorization of anomalous venous drainage was performed, and the relationship with surgical morbidity was assessed.

Results

Forty-one patients were identified. Anomalies were present in 31 patients (76%) consisting of dural sinus stenosis in 28 (68%), dilated emissaries in 26 (63%), and fetal sinuses in 7 (17%). Pfeiffer syndrome was most commonly associated with anomalous drainage (100%). Venous anomalies were associated with elevated intracranial pressure (ICP), shunted hydrocephalus, Chiari malformations, and sleep apnea. In 5 cases, the surgical plan was adjusted based on anomalous anatomy. No mortalities occurred. Intraoperative complication rate was 7.3%, all with anomalous drainage. Median estimated blood loss was 1,100 cc for patients with anomalies versus 400 cc without anomalies (P = 0.181).

Conclusion

Cranial venous anomalies are commonly detected in patients with syndromic craniosynostosis and may affect surgical morbidity and outcome with a higher estimated blood loss, alteration of procedure, and postoperative morbidity. Detailed preoperative imaging of the venous drainage is therefore recommended in cases of syndromic synostosis.

Stenosis Before Thrombosis: Intracranial Hypertension from Jugular Foramen Stenosis Secondary to Renal Osteodystrophy

BACKGROUND

Venous outflow obstructions are rare anatomic findings that can appear with symptoms of elevated intracranial pressure, including headache and vision loss, and can be mistaken for more common diagnoses, such as idiopathic intracranial hypertension (IIH) or cerebral venous sinus thrombosis (CVST). Although venous outflow obstructions have been reported in rare bone dysplasias and congenital abnormalities, to date they have not been reported in renal osteodystrophy (ROD), a relatively common disorder seen in patients with chronic kidney disease.

CASE DESCRIPTION

In this case, the authors describe a patient with marked intracranial hypertension from jugular foramen stenosis secondary to ROD. After diagnosis by CT and magnetic resonance venography, catheter venography confirmed an osseus band around the left jugular bulb, and a 40-mm Hg pressure gradient across the stenotic foramen. The patient subsequently underwent ventriculoperitoneal shunting and optic nerve sheath fenestration with symptom improvement. The postoperative course was significant for development of CVST, necessitating treatment.

CONCLUSIONS

This report reviews the presentation, pathology, and neurosurgical treatment of patients with ROD and venous outflow obstructions, and explores the differential diagnoses of outflow obstructions, IIH, and CVST. To our knowledge, this is the first report of intracranial hypertension from jugular foramen stenosis secondary to renal osteodystrophy.

Skull base morphology in fibroblast growth factor receptor type 2-related faciocraniosynostosis: a descriptive analysis

BACKGROUND

Children with faciocraniosynostosis present skull base abnormalities and may develop hydrocephalus or cerebellar tonsils ectopia (CTE). Several pathophysiological hypotheses were formulated in the past decades to explain these associations. However, no study has described in a genetically homogeneous population with confirmed fibroblast growth factor receptor type 2 (FGFR2) mutation eventual correlations between skull base abnormalities and hydrocephalus or CTE.

OBJECTIVE

To illustrate these features in children <2 years of age with a genetically confirmed FGFR2-related faciocraniosynostosis.

METHODS

We measured the foramen magnum area (FMA) and its sagittal and transversal components: the right, left, and mean area of the jugular foramen; the posterior fossa volume; and the cerebellar volume on preoperative millimetric computed tomography scan slices in 31 children with an FGFR2 mutation (14 with Crouzon syndrome, 11 with Apert syndrome, and 6 with Pfeiffer syndrome). They were compared with 17 children without synostosis. All children were <24 months of age. We correlated all these measures with the presence of hydrocephalus or CTE.

RESULTS

We observed a significantly small FMA in children with Crouzon (P = .03) and in children with Pfeiffer (P = .05) resulting from a reduced sagittal diameter (P = .02 for Crouzon and P = .002 for Pfeiffer). Hydrocephalus was associated with small FMA (P = .02). The jugular foramen area, posterior fossa volume, and cerebellar volume were not associated with hydrocephalus or CTE. Hydrocephalus and CTE were statistically associated (P = .002).

CONCLUSION

Hydrocephalus in FGFR2-related Crouzon and Pfeiffer syndromes is statistically associated with a small FMA. Hydrocephalus is statistically associated with CTE.

Basicranial venous anomalies associated with complex nonsyndromic craniosynostosis in a child

We report the radiological findings of severe bilateral jugular foraminal stenosis along with anomalous basicranial venous drainage in a child with a history of complex nonsyndromic craniosynostosis. CT with 3D reconstructions and MR venography revealed that the lateral sinuses were draining transosseously through several markedly enlarged emissary veins. The main route of transverse and sigmoid sinus drainage was through large mastoid emissaries to the deep cervical veins. There was additional drainage of these mastoid emissaries into the vertebral and paravertebral plexuses as well as into venous collaterals which subsequently reconstituted the internal jugular veins. Basicranial venous anomalies are common among children with complex craniosynostosis, and although they may not resemble intracranial vascular outflow deficiencies, they can pose significant surgical risks. This case emphasizes the need for proper clinical assessment and documentation of anomalous basicranial venous anatomy to facilitate management of complex craniosynostosis patients.

Three-dimensional analysis of foramen magnum and its adjacent structures

The goal of this effort is to evaluate the anatomy of the foramen magnum (FM) using 3-dimensional computed tomography (3D CT), and determine whether or not the anatomical features of vascular structures and condylar foramen (CF) affect the types of FM.The CT angiography records of 101 patients (44 men and 57 women) were retrospectively examined in this study. Details of the FM, CF, and the vertebral and basilar arteries were examined using maximum intensity projection and 3D rendering images. The average age of the 101 patients was 45.28 ± 16.3 years. The 8 types of FM, in order of their frequency of occurrence, are as follows: round (19 cases; 18.8%), 2 semicircles (18; 17.8%), egg-shaped (15; 14.9%), hexagonal (14; 13.9%), tetragonal (11; 10.9%), oval (11; 10.9%), pentagonal (9; 8.9%), and irregular (4; 4%). There was no statistically significant relationship between the anatomical features of the vertebral and basilar arteries and the CF with the different types of FM (P ≥ 0.05). In our study, the diameter of the anteroposterior (AP) FM was 34.7 ± 3.6 mm, and the transverse (T) diameter was 29.5 ± 2.5 mm. The AP and T diameters were significantly higher in men than in women (P = 0.006 and P ≤ 0.001, respectively).Our study revealed that 3D CT is a safe and easy method for visualizing the anatomical structure of the FM and neighboring structures. Furthermore, this study was the first to demonstrate that there is no correlation between the 8 types of FM and the vertebral artery, basilar artery, and CF.

Spring-assisted cranial vault expansion in the setting of multisutural craniosynostosis and anomalous venous drainage: case report

Patients with multisutural craniosynostosis can develop anomalous venous connections between the intracranial sinuses and cutaneous venous system through enlarged emissary veins. Cranial vault remodeling in this subset of patients carries the risk of massive intraoperative blood loss and/or occlusion of collateral draining veins leading to intracranial venous hypertension and raised intracranial pressure, increasing the morbidity of cranial expansion. The authors report the use of spring-mediated expansion as a technique for cranial reconstruction in which the collateral intracranial venous drainage system can be preserved. A patient with bilateral lambdoid, sagittal, and unicoronal synostosis presented for cranial reconstruction. A tracheostomy and ventriculoperitoneal shunt were placed prior to intervention. At the time of reconstruction, a Luckenschadel skull abnormality and Chiari malformation Type I were present. A preoperative CT venogram demonstrated large collateral superficial occipital veins, small bilateral internal jugular veins, and hypoplastic jugular foramina. Collateral flow from the transverse and sigmoid sinuses through large occipital emissary veins was seen. Spring-mediated cranial vault expansion was performed with care to preserve the large collateral veins at the occipital midline. Four springs were placed at each lambdoid and the posterior and anterior sagittal sutures following 1-cm strip suturectomies. Removal of the springs was performed 2 months postoperatively. Cranial vault expansion was performed without disturbing the aberrant intracranial/extracranial venous collateral system. Estimated blood loss was 150 ml. A CT scan obtained 3 months postoperatively showed resolution of the Luckenschadel deformity and a 40% volumetric increase in the skull compared with the preoperative CT. Patients with anomalous venous drainage patterns and multisutural synostosis can undergo spring-mediated cranial vault expansion while preserving the major emissary veins draining the intracranial sinuses. Risks of blood loss, intracranial venous hypertension, and increased intracranial pressure may be decreased compared with traditional techniques of repair.

A unifying theory for the multifactorial origin of cerebellar tonsillar herniation and hydrocephalus in osteopetrosis

OBJECT

Osteopetrosis is a rare congenital metabolic bone disease. There are very few reports in the literature associating cerebellar tonsillar herniation (CTH) and hydrocephalus requiring neurosurgical attention. The authors present cases of osteopetrosis requiring neurosurgical intervention from their practice and offer a detailed account of the literature.

METHODS

A retrospective review was conducted at the authors' institution, and all children with osteopetrosis requiring neurosurgical attention were identified. Medical charts and radiographic studies were reviewed. Data including age at presentation, sex, symptoms at presentation, age at follow-up, the presence of any neurological comorbidities, and surgical procedures performed were recorded.

RESULTS

Four patients were identified as having osteopetrosis requiring neurosurgical attention at the authors' institution between January 1, 2005, and January 1, 2014. There were 3 females and 1 male with an average age at presentation of 11.1 years; patients were observed for a mean of 4.4 years. All of the patients were identified as harboring jugular foraminal stenosis and CTH. Seventy-five percent of these patients developed hydrocephalus, and in those cases a triventricular pattern of dilation was noted. One patient developed syringomyelia. Three of the 4 patients underwent neurosurgical procedures. Cerebrospinal fluid diversion was performed in 2 patients via a ventriculoperitoneal shunt in one case and an endoscopic third ventriculostomy (ETV) in the other. The former patient required a proximal revision at 2 years for bony overgrowth at the site of the bur hole. Two patients underwent a suboccipital decompression. In patients undergoing CSF diversion, there was improvement in ventricle size.

CONCLUSIONS

Variable degrees of hindbrain crowding and/or CTH are mentioned throughout the literature, suggesting that this entity is nearly always present in this patient population. The progressive triventricular hydrocephalus seen in these cases results from a complex combination of both communicating and noncommunicating pathology, which may depend on the type of osteopetrosis, age at presentation, and the presence and degree of venous collateralization, and it appears that the hydrocephalus is more prevalent and more likely to be treated in infants and in the younger, school-aged population. The acquired hindbrain fullness in conjunction with the triventricular pattern of hydrocephalus has kept the authors enthusiastic regarding the use of ETV in these complicated cases.

Three-dimensional computed tomography venography as a guide for cranioplasty in parietal cephalocele

We present cranioplasty for a patient who underwent encephalocele surgery during infancy. Preoperative 3-dimensional computed tomography venography showed the skull defect and abnormal running of the superior sagittal sinus in simultaneous images. Using computed tomography venography images as a guide, we could safely harvest full-thickness calvarial bone from the contralateral side of the superior sagittal sinus.

Suboccipital decompression during posterior cranial vault remodeling for selected cases of Chiari malformations associated with craniosynostosis

OBJECT

The optimal management of Chiari malformations in the setting of craniosynostosis is not well established. In this report the authors describe their outcomes with the combined technique of simultaneous suboccipital decompression (SOD) during posterior cranial vault remodeling (PCVR).

METHODS

A retrospective review was performed of all patients undergoing PCVR and simultaneous SOD. Demographic data, diagnosis, imaging studies, operative intervention, and clinical follow-up were evaluated.

RESULTS

Thirty-four patients were identified as having undergone a simultaneous PCVR/SOD for Chiari malformation associated with craniosynostosis. Eighty-eight percent of these patients had syndromic, multisutural craniosynostosis, and the remaining patients had unilateral lambdoid craniosynostosis. There were no postoperative complications as a direct result from this combined procedure. Two patients required a subsequent direct approach for decompression of the Chiari malformation. The interval between these subsequent surgeries was 3 years and 19 months.

CONCLUSIONS

Chiari malformations are commonly associated with syndromic, complex craniosynostosis and isolated lambdoid craniosynostosis. In appropriately selected patients, a combined posterior cranial vault enlargement and SOD of the foramen magnum is associated with a low complication rate and appears to be an effective procedure.

Craniosynostosis: imaging review and primer on computed tomography

Craniosynostosis is encountered in the pediatric population in isolated or syndromic forms. The resulting deformity depends on the number and type of sutures involved and, in multi-sutural synostosis, the order of suture fusion. Primary craniosynostosis needs to be differentiated from the secondary variety and positional or deformational mimics. Syndromic craniosynostoses are associated with other craniofacial deformities. Evaluation with 3-D CT plays an important role in accurate diagnosis and management; however, implementation of appropriate CT techniques is essential to limit the radiation burden in these children. In this article, the authors briefly review the classification, embryopathogenesis and epidemiology and describe in detail the radiologic appearance and differential diagnoses of craniosynostosis.

Crescent posterior fossa durotomy for occipito-marginal venous sinus preservation: a pilot study

PURPOSE

The standard approach of midline suboccipital craniectomy entails sacrifice of the Occipito-marginal sinus. We have attempted to preserve this venous channel by using a durotomy technique which preserves this system. In a pilot study initiative, two groups of patients using this technique versus the standard approach, were compared in terms of per and post operative benefits, morbidity and complications. The literature with reference to the anatomy and venous flow dynamics of the occipital and marginal sinuses and their significance has been reviewed. Similarly, literature regarding dural closure technique with reference to postoperative complications has also been reviewed.

METHODS

In this novel approach, the dura is opened as a crescent to avoid damage to the occipital sinus. This technique was compared with the standard midline dural opening technique by random usage of both techniques in 24 patients.

RESULTS

The 'crescent' approach has been found to reduce the need for duroplasty, with comfortable primary closure and to reduce the risk of postoperative pseudomeningocele.

CONCLUSIONS

This is a novel dural opening technique which attempts to preserve the normal venous flow physiology. In essence it helps in increased primary dural closures and reduction of Pseudomeningiocele/CSF leak as well as blood loss and venous hypertension.

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.

Chiari malformation associated with craniosynostosis

OBJECT

Chiari malformation (CM) Type I is frequently associated with craniosynostosis. Optimal management of CM in patients with craniosynostosis is not well-established. The goal of this study was to report on a series of pediatric patients with both craniosynostosis and CM and discuss their management.

METHODS

The authors searched the medical records of 383 consecutive patients treated for craniosynostosis at a single institution over a 15-year period to identify those with CM. They recorded demographic data as well as surgical treatment and outcomes for these patients. When MR imaging was performed, cerebellar tonsillar descent was recorded and any other associated findings, such as hydrocephalus or spinal syringes, were noted.

RESULTS

A total of 29 patients with both CM and craniosynostosis were identified. Of these cases, 28% had associated occipital venous abnormalities, 45% were syndromic, and 52% also had hydrocephalus. Chiari malformation was more likely to be present in those patients with isolated lambdoid synostosis (55%), multisuture synostosis (35%), and pansynostosis (80%), compared with patients with coronal synostosis (6%) or sagittal synostosis (3%). All patients underwent surgical repair of craniosynostosis: 16 had craniosynostosis repair as well as CM decompression, and 13 patients did not undergo CM decompression. Of the 7 patients in whom craniosynostosis repair alone was performed, 5 had decreased tonsillar ectopia postoperatively and 5 had improved CSF flow studies postoperatively. Both patients with a spinal syrinx had imaging-documented syrinx regression after craniosynostosis repair. In 12 patients in whom CM was diagnosed after primary craniosynostosis repair, 5 had multiple cranial vault expansions and evidence of elevated intracranial pressure. In 5 cases, de novo CM development was documented following craniosynostosis repair at a mean of 3.5 years after surgery.

CONCLUSIONS

Chiari malformation is frequently seen in patients with both multi- and single-suture lambdoid craniosynostosis. Chiari malformation, and even a spinal cord syrinx, will occasionally resolve following craniofacial repair. De novo development of CM after craniosynostosis repair is not unusual.

External hydrocephalus in infants: six cases with MR venogram and flow quantification correlation

PURPOSE

The cause of external hydrocephalus in infants is largely unknown. However, familial macrocephaly and delayed maturation of the arachnoid granulations are thought to play a part in the idiopathic cases. Secondary cases of external hydrocephalus are associated with hemorrhage, meningitis, and elevated venous pressure. Recently, elevated venous pressure has been shown to be a much more common cause of communicating hydrocephalus in children than previously thought. The purpose of this study is to investigate venous pressure as a cause of external hydrocephalus.

METHODS

Six children with external hydrocephalus underwent an MRI examination including MR venography and MR flow quantification techniques. A chart review was performed to correlate the clinical findings with the MR findings. Six children with normal head circumferences and growth profile served as controls.

RESULTS

The net aqueduct flow in both normal and hydrocephalic children was into the ventricles. There was a spectrum of blood flow findings in the infants with hydrocephalus. (1) Those with normal arterial inflow showed venous outflow stenoses or anomalies. (2) Those with normal MR venograms tended to have elevated cerebral blood inflow.

CONCLUSIONS

The absorption of CSF in infants is into the capillary bed of the deep white matter rather than the arachnoid granulations. Absorption into a capillary bed depends on hydrostatic pressure. Similar to older children with communicating hydrocephalus, the infants in this cohort with external hydrocephalus showed evidence of an elevation in venous pressure. Elevated venous pressure may be a much more common cause of external hydrocephalus than previously recognized.

Chiari type I malformation in children

The diagnosis of Chiari type I malformation (CIM) is more and more frequent in clinical practice due to the wide diffusion of magnetic resonance imaging. In many cases, such a diagnosis is made incidentally in asymptomatic patients, as including children investigated for different reasons such as mental development delay or sequelae of brain injury. The large number of affected patients, the presence of asymptomatic subjects, the uncertainties surrounding the pathogenesis of the malformation, and the different options for its surgical treatment make the management of CIM particularly controversial.This paper reports on the state of the art and the recent achievements about CIM aiming at providing further information especially on the pathogenesis, the natural history, and the management of the malformation, which are the most controversial aspects. A historial review introduces and explains the current classification. Furthermore, the main clinical, radiological, and neurophysiological findings of CIM are described to complete the picture of this heterogeneous and complex disease.

Craniosynostosis: a radiological and surgical perspective

Craniosynostosis is the premature fusion of the cranial sutures. It is identified early in life either due to cosmetic deformity or due to more serious functional complications. Isolated forms of craniosynostosis are much more common and less challenging in their management than their syndromic counterpart. Modern multislice computed tomography and 3D reconstructions have revolutionized surgical planning and follow-up. We review the radiological features of the craniosynostoses, complications, and associated conditions that may alter patient management. Common surgical techniques and postoperative appearances are illustrated in the article.

Predicting factors for the follow-up outcome and management decisions in vein of Galen aneurysmal malformations

PURPOSE

Vein of Galen aneurysmal malformations (VGAMs) are choroidal arteriovenous malformations that develop during an early embryonic stage. Although recent reports have shown improved outcome for these patients, the overall outcome still is poor. In this study, we evaluated the clinical, imaging, and angiographic features that may predict the outcome in VGAM patients.

METHODS

Twenty-five patients diagnosed with VGAM were reviewed for clinical symptoms, including neonatal scoring systems, imaging findings, angioarchitecture, treatment decision, initial treatment age, follow-up timing, and follow-up outcome.

RESULTS

Factors that were significantly associated with a poor outcome (p < 0.05) included neurological symptoms at presentation, a medium-to-low overall neonatal score (<12/21), a very poor score (<2/5) in one (or more) categories, focal parenchymal changes, calcifications, tonsillar herniation, arterial steal, or more than two groups of multiple arterial feeders. The venous drainage pattern and treatment age were not significantly associated with the overall outcome.

CONCLUSIONS

The presence of multiple factors that are related with poor outcome may warrant withholding aggressive treatment, while a small subgroup of carefully selected patients without any of these factors who are clinically asymptomatic may have a good outcome even with conservative management and close follow-up. For all other patients in which treatment is considered, the optimal treatment time is at 4-5 months of age; however, urgent treatment, regardless of age, should be indicated in those that do not have permanent brain damage on imaging with deteriorating congestive heart failure, evidence of arterial steal, or progressive occlusion of the venous outflow.

Age-related peridural hyperemia in craniosynostotic rabbits

OBJECTIVE

Craniosynostosis is the premature fusion of the calvarial sutures and is associated with aesthetic impairment and secondary damage to brain growth. Associated neurological injuries can result from increased intracranial pressure (ICP) and abnormal cerebral blood flow (CBF). Arterial spin-labeling (ASL) MRI was used to assess regional CBF in developing rabbits with early-onset coronal suture synostosis (EOCS) and age-matched wild-type controls (WT).

METHODS

Rabbits were subjected to ASL MRI at or near 10, 25, or 42 days of age. Differences in regional CBF were assessed using one-way ANOVA.

CONCLUSION

CBF was similar in WT and EOCS rabbits with the exception of the peridural surfaces in EOCS rabbits at 25 days of age. A twofold increase in peridural CBF at 25 days of age coincides with a transient increase in ICP. By 42 days of age, CBF in peridural surfaces had decreased.

Abnormal venous drainage in syndromic craniosynostosis and the role of CT venography

OBJECTIVE

Venous hypertension is emerging as a significant contributor to intracranial pressure in children with syndromic craniosysnostosis. This is associated with jugular foramen stenosis or atresia and with the development of collateral emissary veins. We demonstrate how computed tomography venography can document the prevalence of these emissary veins and how their visualisation plays an important role in operative planning.

MATERIALS AND METHODS

Patients with known syndromic craniosynostosis underwent computed tomography venography as part of their routine pre-operative evaluation. The venous drainage pattern was examined in these patients, with a special note of the presence of abnormal venous pathways.

RESULTS

Eleven patients were recruited into the study from ages 3 months to 22 years. All had a diagnosis of syndromic craniosynostosis with six Crouzon's, four Pfeiffer's and one patient with Crouzon's and acanthosis nigricans. Nine of 11 patients had demonstrable evidences of transosseous venous drainage through an identifiable abnormal emissary vein. Four of 11 had a transosseous route as the main mechanism of drainage for the cerebral venous system.

CONCLUSIONS

Patients with syndromic craniosynostosis often demonstrate abnormal venous anatomy, which can have serious consequences on craniofacial surgery, especially when a posterior decompression is being considered. Based on these findings, the authors assert that those children with some syndromic craniosynostosis being considered for surgery should undergo venographic studies as part of their pre-operative evaluation.

Neuroimaging findings in macrocephaly-capillary malformation: a longitudinal study of 17 patients

Here, we report the neuroimaging findings and neurological changes in 17 unpublished patients with Macrocephaly-Capillary Malformation (M-CM). This syndrome has been traditionally known as Macrocephaly-Cutis Marmorata Telangiectatica Congenita (M-CMTC), but we explain why M-CM is a more accurate term for this overgrowth syndrome. We analyzed the 17 patients with available brain MRI or CT scans and compared their findings with features identified by a comprehensive review of published cases. White matter irregularities with increased signal on T2-weighted images were commonly observed findings. A distinctive feature in more than half the patients was cerebellar tonsillar herniation associated with rapid brain growth and progressive crowding of the posterior fossa during infancy. In four such cases, we confirmed that the tonsillar herniation was an acquired event. Concurrently, with the development of these findings, ventriculomegaly (frequently obstructive) and dilated dural venous sinuses were observed in conjunction with prominent Virchow-Robin spaces in many of those in whom cerebellar tonsil herniation had developed. We postulate that this constellation of unusual features suggests a dynamic process of mechanical compromise in the posterior fossa, perhaps initiated by a rapidly growing cerebellum, which leads to congestion of the venous drainage with subsequently compromised cerebrospinal fluid reabsorption, all of which increases the posterior fossa pressure and leads to acquired tonsillar herniation. We make a distinction between congenital Chiari I malformation and acquired cerebellar tonsil herniation in this syndrome. We also observed numerous examples of abnormal cortical morphogenesis, including focal cortical dysplasia, polymicrogyria which primarily involved the perisylvian and insular regions, and cerebral and/or cerebellar asymmetric overgrowth. Other findings included a high frequency of cavum septum pellucidum or vergae, thickened corpus callosum, prominent optic nerve sheaths and a single case of venous sinus thrombosis. One patient was found to have a frontal perifalcine mass resembling a meningioma at age 5 years. This is the second apparent occurrence of this specific tumor in M-CM.

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.

Ventriculoperitoneal shunt failure causing myelopathy in a patient with bilateral jugular vein occlusion

✓The authors describe the case of a 36-year-old woman with bilateral internal jugular vein occlusion, hydrocephalus, and Dandy–Walker variant who presented with myelopathy that was ultimately attributed to ventriculoperitoneal (VP) shunt failure. Computed tomography (CT) angiography of the head and neck revealed epidural venous engorgement within the cervical spine, greater that 50% narrowing of the C2–5 spinal canal, and compression of the cervical spinal cord. After successful shunt revision, postoperative CT angiography revealed decreased venous engorgement as well as decompression of the cervical spinal cord, and the patient’s myelopathy improved. This case represents a fascinating clinical presentation of VP shunt failure, highlighting the physiological importance of the external jugular pathways involved in cerebral venous drainage.

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.

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.

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.

CT imaging of craniofacial malformations

Because of its superior depiction of bone detail, CT is a useful tool in the characterization of CF deformities and presurgical planning. Modern CT scanners and workstations provide 2D techniques such as multiplanar reformats and 3D techniques, such as MIP and volume renderings, which may be used effectively in the diagnosis and management of patients with CF malformations.

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.