Venous hypertension in syndromic and complex craniosynostosis: the abnormal anatomy of the jugular foramen and collaterals

Maximizing the functional benefits of posterior calvarial vault distraction in syndromic craniosynostoses: a nuanced approach to volume, vein, vector, and the vexed challenge of functional outcome in craniosynostoses

PURPOSE

To evaluate indications, techniques, nuances, and outcomes of posterior cranial vault distraction (PCVD) in children with craniosynostoses.

METHODS

We performed clinical assessments, multidimensional CT, MRI brain rapid protocol, ophthalmological evaluation, sleep study, and nasal endoscopy (if indicated). Detailed data was collected in Excel. Customized craniotomy (supratorcular or subtorcular), distraction vectors, strategic barrel staving on stenosed bones (other than lambdoid), and ~ 2 cm relief craniectomy for venous decompression were employed. Additional procedures were performed for the frontal and midface aspects during distractor removal based on functional needs.

RESULTS

Thirty-seven patients (ages 4-204 months, mean 32.94 months) underwent PCVD. Supratorcular PCVD in 8, subtorcular in 29. The distraction vector was posterior-horizontal in 28 cases and posterior-inferior in 9. Strategic barrel staving was used in 8 cases, and venous decompression in 24. Initial assessments showed satisfactory clinical and radiological outcomes. Long-term follow-up indicated seven of 11 patients with hydrocephalus required a ventriculoperitoneal shunt, and two needed additional PCVD procedures due to symptom recurrence. Average intracranial volume increased by 186 ± 42.67 cm3 (18 patients), and the average distraction achieved was 21 ± 2.64 mm (37 patients). Additional procedures at the time of distractor removal included fronto-facial or monobloc advancement (n = 3), isolated fronto-orbital advancement and remodeling (n = 13), and midface distraction for airway issues (monobloc advancement, n = 3; isolated midface, n = 9). Nine patients underwent all three procedures in sequence.

CONCLUSION

PCVD is an accepted surgical strategy for craniosynostosis with posterior calvarial involvement. Our technical modifications aim to enhance functional and aesthetic outcomes without increasing morbidity.

CSF flow measurement in the mesencephalic aqueduct using 2D cine phase-contrast MRI in dogs with communicating internal hydrocephalus, ventriculomegaly, and physiologic ventricular spaces

Background

Brachycephalic dogs are overrepresented with ventricular enlargement. Cerebrospinal fluid (CSF) flow dynamics are not completely understood. MRI techniques have been used for the visualization of CSF dynamics including phase-contrast imaging.

Objectives

This study aimed to determine a causality between CSF flow and ventriculomegaly or hydrocephalus and to compare CSF flow dynamics among dogs with ventriculomegaly, internal hydrocephalus, and physiologic ventricles.

Animals

A total of 51 client-owned dogs were included in the study.

Methods

Magnetic resonance imaging (MRI)-based FLASH sequences and phase-contrast images of the brain were obtained, and the ROI was placed at the level of the mesencephalic aqueduct. ECG monitoring was performed parallel to MRI acquisition. Evaluation of flow diagrams and processing of phase-contrast images were performed using commercially available software (Argus VA80A, Siemens AG Healthcare Sector, Erlangen, Germany). Dogs were divided into three groups: Group 1 consisted of brachycephalic dogs with ventriculomegaly (group 1A) or internal hydrocephalus (group 1B), group 2 consisted of brachycephalic dogs with normal ventricles, and group 3 consisted of meso- to dolichocephalic dogs with normal ventricles.

Results

Group 1 had a higher median Vrost (4.32 cm/s; CI: 2.94-6.33 cm/s) and Vcaud (-6.1 cm/s, CI: 3.99-9.33 cm/s) than group 2 (Vrost: 1.99 cm/s; CI 1.43-2.78 cm/s; Vcaud: 2.91 cm/s, CI: 2.01-4.21 cm/s; p = 0.008; p = 0.03) and group 3 (Vrost:1.85 cm/s, CI: 1.31-2.60 cm/s; Vcaud - 2.46 cm/s, CI 1.68-3.58 cm/s; p = 0.01; p = 0.02). The median Volcaud of group 1 (-0.23 mL/min, CI: 0.13-0.42 mL/min) was higher than that of group 2 (-0.09 mL/min, CI: 0.05 mL/min and 0.15 mL/min) (p = 0.03). Groups 1A and 1B did not differ in Vcaud, Vrost, Volcaud, and Volrost. Group 1A and 1B showed a higher median Vrost (4.01 cm/s, CI: 2.30-7.05 cm/s; 5.94 cm/s, CI: 2.16-7.88 cm/s) than group 2 (1.85 cm/s, CI: 1.24-2.80 cm/s.) (p = 0.03; p = 0.004).

Conclusion and clinical importance

Increased CSF flow velocities in rostral and caudal directions are present in dogs with ventriculomegaly and internal hydrocephalus compared to normal controls.

Are Chiari Malformation and Basilar Invagination Associated with Jugular Foramen Stenosis?

OBJECTIVE

We compared the diameter of the jugular foramen (JF) between normal individuals and those with a diagnosis of craniovertebral junction abnormalities, such as Chiari malformation type I (CMI) and/or basilar invagination (BI).

METHODS

This cross-sectional analytical study measured the diameter of the right and left JF on magnetic resonance imaging scans of patients divided into 4 groups: 68 with combined CMI and BI (CMI+BI), 42 with isolated BI, 45 with isolated CMI, and 102 control cases. The t test determined sex differences, and univariate analysis of variance with Tukey's post hoc test assessed JF differences between groups.

RESULTS

Considering all combinations of laterality and sex, the CMI+BI group had a JF narrower than their respective control groups. The JF was bilaterally narrower in the BI group than in the control group only in the women. Regardless of laterality, the CMI group had a wider JF than did the CMI+BI group in men and did not differ from that of the control group. In the female patients with CMI, the right JF did not differ from that of the controls and was wider than that in the CMI+BI group. Also, the left JF was narrower than that in the control group and did not differ from that in the CMI+BI group.

CONCLUSIONS

JF narrowing is associated with CMI and BI when combined in the same patient. When CMI or BI are detected separately, they do not imply evident changes in JF morphometry. It is expected that these findings could bring empiric substrate to support theories that claim a possible role of intracranial pressure disturbances as a triggering factor for CMI.

Jugular foramen stenosis in external hydrocephalus in infants

OBJECTIVE

To measure the size of jugular foramina in infants affected by external hydrocephalus (EH) and in a control group, to support the hypothesis that a jugular foramen (JF) stenosis may determine dural venous sinus alterations and increased venous outflow resistance as main pathophysiological factor.

METHODS

Minimum, maximum, and mean values of JF areas were measured in a series of phase-contrast magnetic resonance venous angiography (angio MRV PCA3D) performed on 81 infants affected by EH. Results were compared with a group of 54 controls.

RESULTS

Smaller JF area was significantly smaller in patients versus controls (43.1 ± 14.6 vs. 52.7 ± 17.8; p < 0.001) resulting in a significantly smaller mean JF areas in patients vs. controls (51.6 ± 15.8 vs. 57.0 ± 18.3; p = 0.043). In patients, smaller JF areas were significantly associated with higher venous obstruction grading score (VOGS) both on the right (p = 0.018) and on the left side (p = 0.005). Positional plagiocephaly (cranial vault asymmetry index > 3.5%) was more frequent among EH patients than controls (38/17) but the difference was not significant (p = 0.07). In the 38 plagiocephalic patients, JF area was smaller on the flattened side than the contralateral in a significant number of cases both in right (21/7) and left (9/1) plagiocephaly (p < 0.0005) as well as the mean area (48.2 + 16.4 mm2 vs. 57.5 + 20.7 mm2, p = 0.002) and VOGS was significantly higher on the plagiocephalic side than on the contralateral side (1.6 ± 1.1 vs. 1.1 ± 0.9, p = 0.019).

CONCLUSION

In this series of infants affected by EH, the mean size of the ostium of both JF resulted significantly smaller than controls. JF stenosis was significantly associated with higher degrees of venous obstruction on both sides, suggesting a direct extrinsic effect of JF size on dural sinus lumen and possible consequent effect on venous outflow resistance. Positional plagiocephaly, when present, was associated with a decreased JF area and increased VOGS on the flattened side.

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.

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.

Multisuture and syndromic craniosynostoses: Simplifying the complex

Most complex craniosynostoses are managed the same way as syndromic craniosynostoses (SCs), as these patients often experience similar problems regarding cognition and increased intracranial pressure (ICP). The evaluation and treatment plan for craniosynostoses is complex, and this, additionally, is complicated by the age at presentation. In this article, the authors review the complexity of SCs in the presentation and management. An algorithm is necessary for such multifaceted and multidimensional pathology as craniosynostoses. In most algorithms, posterior calvarial distraction is a consistent early option for complex craniosynostoses presenting early with raised ICP. Addressing the airway early is critical when significant airway issues are there. All other surgical interventions are tailored on the basis of presentation and age.

Syndromic Craniosynostosis: Unique Management Considerations

Craniosynostosis involves the premature fusion of 1 or more cranial sutures and commonly presents as an isolated, nonsyndromic diagnosis. A subset of patients have syndromic craniosynostosis. Several unique considerations must be taken into account when managing patients with syndromic craniosynostosis. A multidisciplinary craniofacial team with a central coordinator is particularly useful for coordinating care among various specialists, and close monitoring is mandatory owing to the increased risk of intracranial hypertension. Surgical management varies among centers, but core options include fronto-orbital advancement with cranial vault remodeling, posterior vault expansion, endoscopic-assisted suturectomy with postoperative orthotic therapy, and midface advancement.

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.

Adult Saethre-Chotzen Syndrome: A Unique Abnormal Breathing Pattern

ABSTRACT

A 35-year-old male with Saethre-Chotzen syndrome presented with severe complaints. Neuroimaging showed a Chiari-I malformation, mild ventriculomegaly, a syrinx of the wide central canal, and various cerebral vascular anomalies including a large occipital emissary vein on the right. Ultrasound of this vein confirmed blocking of the outflow-track when turning his head to the right, which also provoked the headaches and bruit. Polysomnography revealed severe positional sleep apnea with a mixed breathing pattern, the central components consisted of periodic breathing with, at times, crescendo-decrescendo reminiscent of a Cheyne-Stokes versus Biot breathing pattern, pointing to possible brain stem/pontine problems. Continuous positive airway pressure was initiated, and the patient was instructed to avoid sleeping in the right lateral position. One year later, nearly all his complaints have resolved. A questionnaire was sent to all adult Saethre-Chotzen patients in our craniofacial unit, none reported any of the severe symptoms as described by our index case.

Syndrome-related outcomes following posterior vault distraction osteogenesis

PURPOSE

The most commonly occurring syndromic craniosynostoses are Apert syndrome, Crouzon syndrome, Pfeiffer syndrome, and Saethre-Chotzen syndrome. There is insufficient data regarding postoperative syndrome-related outcomes following the posterior vault distraction osteogenesis (PVDO) procedure, as well as data addressing whether or not additional procedures will be subsequently necessary to comprehensively treat children who undergo PVDO. Thus, the objective of this study is to describe and compare syndrome-related potential complications and outcomes associated with the PVDO procedure.

METHODS

An observational retrospective study was performed on consecutive patients (n=24) with Apert syndrome, Crouzon syndrome, Pfeiffer syndrome, or Saethre-Chotzen syndrome, respectively, who underwent PVDO between 2012 and 2019. Demographic data (patient gender and age when the PVDO procedure was performed), diagnosis, surgery-related data, and outcome data (perioperative and midterm complications and need for additional surgery) were verified.

RESULTS

Total relative blood transfusion volumes per kilogram for the patients were as follows: 22.75 ± 9.30 ml for Apert syndrome, 10.73 ± 2.28 ml for Crouzon syndrome (Apert versus Crouzon, p<0.05), 18.53 ± 8.08 ml for Pfeiffer syndrome, and 19.74 ± 9.12 ml for Saethre-Chotzen syndrome. None of the patients required a secondary procedure to alleviate intracranial pressure except for a Saethre-Chotzen patient.

CONCLUSION

PVDO is an effective technique to address elevated intracranial pressure in SC patients that alleviates the need for secondary procedures at midterm follow-up. Apert syndrome patients presented relatively higher total blood transfusion rates than Crouzon syndrome patients who were operated on at a later age and weighed more.

Sinus pericranii-unusual anatomic obstacle to posterior decompression on an amniotic band sequence

Abnormal venous drainage in patients with craniofacial anomalies is relativity uncommon. Sinus pericranii is a rare vascular malformation characterized by communication between intracranial dural sinuses and extracranial venous drainage systems. The association between sinus pericranii and amniotic band syndrome has not been described. We report on a 7-month-old girl diagnosed with amniotic band sequence who underwent posterior fossa decompression due to intracranial hypertension and Chiari malformation type I. The computed tomography and magnetic resonance identified the connection between the sagittal sinus and the scalp. During the operation, the presence of sinus pericranii was a complicating factor limiting the proper exposure because of the risk of bleeding. Patients with craniofacial anomalies and sinus pericranii present an increased risk of serious surgical complications and consequences from craniofacial surgery, especially from cranioplasty and posterior decompression. Special attention must be paid to abnormal venous drainage, and vascular imaging studies are sometimes required.

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.

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.

Bilateral Severely Stenotic Jugular Foramen: Diagnosis and Management from the Otologist/Neurotologist Point of View

Bilateral jugular foramen stenosis with jugular bulb and vein aplasia is rare in nonsyndromic craniosynostosis and usually diagnosed during childhood. We present a case of bilateral jugular foramen stenosis with jugular bulb and vein aplasia, with subsequent persistence and enlargement of the fetal venous anastomosis in the middle and posterior cranial fossa, along with a review of the literature about this anatomical abnormality, highlighting the surgical challenges and management from the otologist/neurotologist point of view.

Dural sinus volume in children with syndromic craniosynostosis and intracranial hypertension

OBJECTIVE

Intracranial hypertension is a major concern in children with syndromic craniosynostosis (sCS). Cerebral venous hypertension caused by cerebral venous outflow obstruction is believed to contribute to intracranial hypertension. The authors therefore hypothesized that cerebral venous volume would be increased in those children with sCS and intracranial hypertension.

METHODS

In a case series of 105 children with sCS, of whom 32 had intracranial hypertension, cerebral MRI techniques were used to quantify the volume of the superior sagittal sinus, straight sinus (StrS), and both transverse sinuses.

RESULTS

Linear regression showed that total cerebral venous volume increased by 580.8 mm3 per cm increase in occipitofrontal head circumference (p < 0.001). No significant difference was found between the intracranial hypertension group and the nonintracranial hypertension group (p = 0.470). Multivariate ANOVA showed increased StrS volume (as a proportion of total volume) in the intracranial hypertension group (8.5% vs 5.1% in the nonintracranial hypertension group, p < 0.001). Multivariate logistic regression showed that a 100-mm3 increase in StrS volume is associated with increased odds of having intracranial hypertension by 60% (OR 1.60, 95% CI 1.24-2.08).

CONCLUSIONS

Although intracranial hypertension was not associated with total cerebral venous volume increase, it was associated with an isolated increase in StrS volume. Hence, it is unlikely that general cerebral venous outflow obstruction is the mechanism of intracranial hypertension in sCS. Rather, these findings indicate either a central cerebral vulnerability to intracranial hypertension or a mechanism involving venous blood redistribution.

Cerebral blood flow in children with syndromic craniosynostosis: cohort arterial spin labeling studies

OBJECTIVE

In comparison with the general population, children with syndromic craniosynostosis (sCS) have abnormal cerebral venous anatomy and are more likely to develop intracranial hypertension. To date, little is known about the postnatal development change in cerebral blood flow (CBF) in sCS. The aim of this study was to determine CBF in patients with sCS, and compare findings with control subjects.

METHODS

A prospective cohort study of patients with sCS using MRI and arterial spin labeling (ASL) determined regional CBF patterns in comparison with a convenience sample of control subjects with identical MRI/ASL assessments in whom the imaging showed no cerebral/neurological pathology. Patients with SCS and control subjects were stratified into four age categories and compared using CBF measurements from four brain lobes, the cerebellum, supratentorial cortex, and white matter. In a subgroup of patients with sCS the authors also compared longitudinal pre- to postoperative CBF changes.

RESULTS

Seventy-six patients with sCS (35 female [46.1%] and 41 male [53.9%]), with a mean age of 4.5 years (range 0.2-19.2 years), were compared with 86 control subjects (38 female [44.2%] and 48 male [55.8%]), with a mean age of 6.4 years (range 0.1-17.8 years). Untreated sCS patients < 1 year old had lower CBF than control subjects. In older age categories, CBF normalized to values observed in controls. Graphical analyses of CBF by age showed that the normally expected peak in CBF during childhood, noted at 4 years of age in control subjects, occurred at 5-6 years of age in patients with sCS. Patients with longitudinal pre- to postoperative CBF measurements showed significant increases in CBF after surgery.

CONCLUSIONS

Untreated patients with sCS < 1 year old have lower CBF than control subjects. Following vault expansion, and with age, CBF in these patients normalizes to that of control subjects, but the usual physiological peak in CBF in childhood occurs later than expected.

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

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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.

Muenke syndrome: long-term outcome of a syndrome-specific treatment protocol

OBJECTIVE

The authors evaluated the long-term outcome of their treatment protocol for Muenke syndrome, which includes a single craniofacial procedure.

METHODS

This was a prospective observational cohort study of Muenke syndrome patients who underwent surgery for craniosynostosis within the first year of life. Symptoms and determinants of intracranial hypertension were evaluated by longitudinal monitoring of the presence of papilledema (fundoscopy), obstructive sleep apnea (OSA; with polysomnography), cerebellar tonsillar herniation (MRI studies), ventricular size (MRI and CT studies), and skull growth (occipital frontal head circumference [OFC]). Other evaluated factors included hearing, speech, and ophthalmological outcomes.

RESULTS

The study included 38 patients; 36 patients underwent fronto-supraorbital advancement. The median age at last follow-up was 13.2 years (range 1.3-24.4 years). Three patients had papilledema, which was related to ophthalmological disorders in 2 patients. Three patients had mild OSA. Three patients had a Chiari I malformation, and tonsillar descent < 5 mm was present in 6 patients. Tonsillar position was unrelated to papilledema, ventricular size, or restricted skull growth. Ten patients had ventriculomegaly, and the OFC growth curve deflected in 3 patients. Twenty-two patients had hearing loss. Refraction anomalies were diagnosed in 14/15 patients measured at ≥ 8 years of age.

CONCLUSIONS

Patients with Muenke syndrome treated with a single fronto-supraorbital advancement in their first year of life rarely develop signs of intracranial hypertension, in accordance with the very low prevalence of its causative factors (OSA, hydrocephalus, and restricted skull growth). This illustrates that there is no need for a routine second craniofacial procedure. Patient follow-up should focus on visual assessment and speech and hearing outcomes.

Chiari I-a 'not so' congenital malformation?

The term Chiari I malformation (CIM) is imbedded in the paediatric neurosurgical lexicon; however, the diagnostic criteria for this entity are imprecise, its pathophysiology variable, and the treatment options diverse. Until recently, CIM has been considered to be a discrete congenital malformation requiring a uniform approach to treatment. Increasingly, it is recognised that this is an oversimplification and that a more critical, etiologically based approach to the evaluation of children with this diagnosis is essential, not only to select those children who might be suitable for surgical treatment (and, of course those who might be better served by conservative management) but also to determine the most appropriate surgical strategy. Whilst good outcomes can be anticipated in the majority of children with CIM following foramen magnum decompression, treatment failures and complication rates are not insignificant. Arguably, poor or suboptimal outcomes following treatment for CIM reflect, not only a failure of surgical technique, but incorrect patient selection and failure to acknowledge the diverse pathophysiology underlying the phenomenon of CIM. The investigation of the child with 'hindbrain herniation' should be aimed at better understanding the mechanisms underlying the herniation so that these may be addressed by an appropriate choice of treatment.

The Chiari I malformation

As with many pathologies, the course of our understanding of the Chiari I malformation (CIM) has developed extensively over time. The early descriptions of the Chiari malformations by Hans Chiari in 1891 opened the door for future classification and research on this topic. However, even over a long timeframe, our understanding of the pathophysiology and, more importantly, treatment, remained in its infancy. As recently as the 1970s, CIM was not discussed in popular neurology textbooks. Syringomyelia is listed as a degenerative disorder with no satisfactory treatment. Radiation therapy was considered an option in treatment, and surgery was thought to play no role. During the last 40 years, equivalent to the duration of a neurosurgical career, our understanding of the pathophysiology and natural history of CIM, coupled with modern MRI, has improved the treatment paradigm for this patient population. More importantly, it has given us evidence confirming that CIM is a disorder responsive to surgical intervention, giving patients once thought to be destined for lifelong disability a comparatively normal life after treatment. The purpose of this article is to offer a review of CIM and its important associated entities. The authors will discuss the evolution in understanding of the Chiari malformation and, importantly, distinguish between symptomatic CIM and asymptomatic tonsillar ectopia, based on imaging and presenting symptomatology. They will discuss techniques for surgical intervention, expected outcomes, and complications after surgery. Proper patient selection for surgery based on appropriate symptomatology is tantamount to achieving good surgical outcomes in this population, separating those who can be helped by surgery from those who are unlikely to improve. While our knowledge of the Chiari malformations continues to improve through the efforts of clinical and basic science researchers, surgeons, and patients, our current understanding of these entities represents a monumental improvement in patient care over a relatively short time period.

Syndromic Craniosynostosis: Complexities of Clinical Care

Patients with syndromic craniosynostosis have a molecularly identified genetic cause for the premature closure of their cranial sutures and associated facial and extra-cranial features. Their clinical complexity demands comprehensive management by an extensive multidisciplinary team. This review aims to marry genotypic and phenotypic knowledge with clinical presentation and management of the craniofacial syndromes presenting most frequently to the craniofacial unit at Great Ormond Street Hospital for Children NHS Foundation Trust.

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.

Staged Raising of a Coronal Flap for Fronto-Orbital Advancement and Remodeling in Saethre-Chotzen Syndrome Complicated by Sinus Pericranii

This article reports the surgical management of a 3-month-old girl with Saethre-Chotzen syndrome, who presented with bicoronal synostosis and a large midline sinus pericranii with abnormal cerebral venous drainage via scalp veins. Raised intracranial pressure was demonstrated on monitoring, indicating the need for calvarial expansion necessitating a coronal access incision. A 2-staged delayed raising of the coronal flap was performed to reduce the potential risk of cerebral venous infarction. Monitoring for clinical sequelae and a computerised tomography venogram followed each of these procedures, demonstrating successful redirection of the venous drainage of the brain posteriorly. Finally, a successful fronto-orbital advancement and remodeling procedure was performed with no complications.

Pilot study of intracranial venous physiology in craniosynostosis

OBJECTIVE In addition to craniocerebral disproportion, other factors, such as Chiari malformation type I, obstructive sleep apnea, and venous outflow obstruction, are considered to have a role in the occurrence of intracranial hypertension in craniosynostosis. This pilot study examined cerebral venous flow velocity to better characterize the complex intracranial venous physiology of craniosynostosis. METHODS The authors performed a prospective cohort study of craniosynostosis patients (n = 34) referred to a single national (tertiary) craniofacial unit. Controls (n = 28) consisted of children who were referred to the unit's outpatient clinic and did not have craniosynostosis. Transfontanelle ultrasound scans with venous Doppler flow velocity assessment were performed at the first outpatient clinic visit and after each surgery, if applicable. Mean venous blood flow velocities of the internal cerebral vein (ICV_v) and the superior sagittal sinus (SSS_v) were recorded and blood flow waveform was scored. RESULTS Preoperatively, SSS_v was decreased in craniosynostosis patients compared with controls (7.57 vs 11.31 cm/sec, p = 0.009). ICV_v did not differ significantly between patients and controls. Postoperatively, SSS_v increased significantly (7.99 vs 10.66 cm/sec, p = 0.023). Blood flow waveform analyses did not differ significantly between patients and controls. CONCLUSIONS Premature closure of cranial sutures was associated with decreased SSS_v but not ICV_v; indicating an effect on the superficial rather than deep venous drainage. Further Doppler ultrasound studies are needed to test the hypothesis that at an early stage of craniosynostosis pathology SSS_v, but not pulsatility, is abnormal, and that abnormality in both SSS_v and the superficial venous waveform reflect a more advanced stage of evolution in suture closure.

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.

Sleep Architecture Linked to Airway Obstruction and Intracranial Hypertension in Children with Syndromic Craniosynostosis

BACKGROUND

Children with syndromic craniosynostosis often have obstructive sleep apnea and intracranial hypertension. The authors aimed to evaluate (1) sleep architecture, and determine whether this is influenced by the presence of obstructive sleep apnea and/or intracranial hypertension; and (2) the effect of treatment on sleep architecture.

METHODS

This study included patients with syndromic craniosynostosis treated at a national referral center, undergoing screening for obstructive sleep apnea and intracranial hypertension. Obstructive sleep apnea was identified by polysomnography, and categorized into no, mild, moderate, or severe. Intracranial hypertension was identified by the presence of papilledema on funduscopy, supplemented by optical coherence tomography and/or intracranial pressure monitoring. Regarding sleep architecture, sleep was divided into rapid eye movement or non-rapid eye movement sleep; respiratory effort-related arousals and sleep efficiency were scored.

RESULTS

The authors included 39 patients (median age, 5.9 years): 19 with neither obstructive sleep apnea nor intracranial hypertension, 11 with obstructive sleep apnea (four moderate/severe), six with intracranial hypertension, and three with obstructive sleep apnea and intracranial hypertension. Patients with syndromic craniosynostosis, independent of the presence of mild obstructive sleep apnea and/or intracranial hypertension, have normal sleep architecture compared with age-matched controls. Patients with moderate/severe obstructive sleep apnea have a higher respiratory effort-related arousal index (p < 0.01), lower sleep efficiency (p = 0.01), and less rapid eye movement sleep (p = 0.04). An improvement in sleep architecture was observed following monobloc surgery (n = 5; rapid eye movement sleep, 5.3 percent; p = 0.04).

CONCLUSIONS

Children with syndromic craniosynostosis have in principle normal sleep architecture. However, moderate/severe obstructive sleep apnea does lead to disturbed sleep architecture, which fits within a framework of a unifying theory for obstructive sleep apnea, intracranial hypertension, and sleep.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Patterns and Rates of Supplementary Venous Drainage to the Internal Jugular Veins

BACKGROUND AND PURPOSE

Several studies have found supplemental venous drainage channels in addition to bilateral internal jugular veins for cerebral venous efflux. We performed this study to characterize the supplemental venous outflow patterns in a consecutive series of patients undergoing detailed cerebral angiography with venous phase imaging.

METHODS

The venographic phase of the arteriogram was reviewed to identify and classify supplemental cerebral venous drainage into anterior (cavernous venous sinus draining into pterygoid plexus and retromandibular vein) and posterior drainage pattern. The posterior drainage pattern was further divided into plexiform pattern (with sigmoid venous sinus draining into the paravertebral venous plexus), and solitary vein pattern (dominant single draining deep cervical vein) drainage. The posterior plexiform pattern was further divided into 2 groups: posterior plexiform with or without prominent solitary vein.

RESULTS

Supplemental venous drainage was seen ipsilateral to internal jugular vein in 76 (43.7%) of 174 venous drainages (87 patients) analyzed. The patterns were anterior (n = 23, 13.2%), posterior plexiform without prominent solitary vein (n = 40, 23%), posterior plexiform with prominent solitary vein (n = 62, 35.6%), and posterior solitary vein alone (n = 3, 1.7%); occipital emissary veins and/or transosseous veins were seen in 1 supplemental venous drainage. Concurrent ipsilateral anterior and posterior supplemental drainage was seen in 6 of 174 venous drainages analyzed.

CONCLUSIONS

We provide an assessment of patterns and rates of supplementary venous drainage to internal jugular veins to improve our understanding of anatomical and physiological aspects of cerebral venous drainage.

Abnormal transcranial Doppler cerebral blood flow velocity and blood pressure profiles in children with syndromic craniosynostosis and papilledema

OBJECTIVE

Children with syndromic craniosynostosis are at risk of intracranial hypertension. This study aims to examine patient profiles of transcranial Doppler (TCD) cerebral blood flow velocity (CBFv) and systemic blood pressure (BP) in subjects with and without papilledema at the time of surgery, and subsequent effect of cranial vault expansion.

METHODS

Prospective study of patients treated at a national referral center. Patients underwent TCD of the middle cerebral artery 1 day before and 3 weeks after surgery. Measurements included mean CBFv, peak systolic velocity, and end diastolic velocity; age-corrected resistive index (RI) was calculated. Systemic BP was recorded. Papilledema was used to indicate intracranial hypertension.

RESULTS

Twelve patients (mean age 3.1 years, range 0.4-9.5) underwent TCD; 6 subjects had papilledema. Pre-operatively, patients with papilledema, in comparison to those without, had higher TCD values, RI, and BP (all p = 0.04); post-operatively, the distinction regarding BP remained (p = 0.04). There is a significant effect of time following vault surgery with a decrease in RI (p < 0.01).

CONCLUSION

Patients with syndromic craniosynostosis who have papilledema have a different TCD profile with raised BP. Vault surgery results in increased CBFv and decrease in RI, however the associated systemic BP response to intracranial hypertension remained at short-term follow-up.