The role of venous sinus outflow obstruction in pediatric idiopathic intracranial hypertension

Interrelation Between Cerebrospinal Fluid Pressure, Intracranial Morphology and Venous Hemodynamics Studied by 4D Flow MRI

PURPOSE

To quantify the effects of CSF pressure alterations on intracranial venous morphology and hemodynamics in idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH) and assess reversibility when the underlying cause is resolved.

METHODS

We prospectively examined venous volume, intracranial venous blood flow and velocity, including optic nerve sheath diameter (ONSD) as a noninvasive surrogate of CSF pressure changes in 11 patients with IIH, 11 age-matched and sex-matched healthy controls and 9 SIH patients, before and after neurosurgical closure of spinal dural leaks. We applied multiparametric MRI including 4D flow MRI, time-of-flight (TOF) and T2-weighted half-Fourier acquisition single-shot turbo-spin echo (HASTE).

RESULTS

Sinus volume overlapped between groups at baseline but decreased after treatment of intracranial hypotension (p = 0.067) along with a significant increase of ONSD (p = 0.003). Blood flow in the middle and dorsal superior sagittal sinus was remarkably lower in patients with higher CSF pressure (i.e., IIH versus controls and SIH after CSF leak closure) but blood flow velocity was comparable cross-sectionally between groups and longitudinally in SIH.

CONCLUSION

We were able to demonstrate the interaction of CSF pressure, venous volumetry, venous hemodynamics and ONSD using multiparametric brain MRI. Closure of CSF leaks in SIH patients resulted in symptoms suggestive of increased intracranial pressure and caused a subsequent decrease of intracranial venous volume and of blood flow within the superior sagittal sinus while ONSD increased. In contrast, blood flow parameters from 4D flow MRI did not discriminate IIH, SIH and controls as hemodynamics at baseline overlapped at most vessel cross-sections.

Imaging the Cerebral Veins in Pediatric Patients: Beyond Dural Venous Sinus Thrombosis

The range of intracranial venous anomalies in children differs from that in adults. As a commonly encountered highly morbid disease, sinovenous thrombosis has been discussed extensively in the literature, and the associated imaging considerations are similar in pediatric and adult patients. The authors shift the focus to less frequently discussed cerebral venous diseases in pediatric patients. First, the practical embryology pertinent to malformations, syndromes, and variants such as vein of Galen aneurysmal malformation, Sturge-Weber syndrome, and developmental venous anomalies are discussed. Second, anatomic considerations that are applicable to neuroimaging in pediatric patients with cerebral venous anomalies are reviewed. In the discussion of anatomy, special attention is given to the medullary venous system that serves the cerebral white matter, superficial cortical veins (tributaries of the dural venous sinuses), and bridging veins, which carry blood from the superficial cortical veins through the potential subdural space into the dural venous sinuses. Third, the selection of imaging modalities (US, CT and CT venography, and MRI) is addressed, and various MR venographic pulse sequences (time-of-flight, phase-contrast, and contrast-enhanced sequences) are compared. Finally, a broad variety of congenital and acquired superficial and deep venous diseases in children are reviewed, with emphasis on less frequently discussed entities involving the medullary (eg, deep medullary venous engorgement and thrombosis, periventricular hemorrhagic venous infarction due to germinal matrix hemorrhage), cortical (eg, cortical venous thrombosis), and bridging (eg, acute and chronic manifestations of injury in abusive head trauma) veins, as well as the deep veins and dural venous sinuses (eg, varix). © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Life-threatening idiopathic intracranial hypertension: the role of venous sinus stenting

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a clinical syndrome characterised by raised intracranial pressure with no discernible aetiology. It is relatively rare in children and its demographic features may differ from those of adults. The relationship between IIH and venous sinus stenosis (VSS) is well known. As VSS plays an important role in the pathophysiology, treatments have been developed aimed at improving venous blood outflow in refractory IIH. In the last two decades, venous sinus stenting has emerged as a treatment option in cases where stenosis is documented.

METHODS AND RESULTS

The scientific literature on paediatric cases of IIH and its treatment with venous sinus stenting was analysed. We present the case of a 6-year-old girl with a life-threatening presentation of IIH, who was treated with transverse sinus stenting and a lumboperitoneal shunt. We summarise the characteristic of paediatric stenting cases reported and review the literature focusing on the main aspects of venous sinus stenting.

CONCLUSION

VSS stenting could be a treatment tool for the acute presentation of IIH with severe symptoms and VSS plus an elevated trans-stenotic pressure gradient. However, in some cases, additional surgical treatment may be necessary.

Transmantle and transvenous pressure gradients in cerebrospinal fluid disorders

Hydrocephalus is the symptomatic endpoint of a variety of disease processes. Simple hydrodynamic models have failed to explain the entire spectrum of cerebrospinal fluid (CSF) disorders. Physical principles argue that for ventricles to expand, they must be driven by a force, Fishman's transmantle pressure gradient (TMPG). However, the literature to date, reviewed herein, is heterogenous and fails to consistently measure a TMPG. The venous system, like CSF, traverses the cerebral mantle, and thus analogous transparenchymal and transvenous pressure gradients have been described, reliant on the differential haemodynamics of the deep and superficial venous systems. Interpreting CSF disorders through these models provides new insights into the possible pathophysiological mechanisms underlying these diseases. However, until more sophisticated testing is performed, these models should remain heuristics.

The incidence of obesity, venous sinus stenosis and cerebral hyperaemia in children referred for MRI to rule out idiopathic intracranial hypertension at a tertiary referral hospital: a 10 year review

BACKGROUND

Children referred to a tertiary hospital for the indication, "rule out idiopathic intracranial hypertension (IIH)" may have an increased risk of raised venous sinus pressure. An increase in sinus pressure could be due to obesity, venous outflow stenosis or cerebral hyperemia. The purpose of this paper is to define the incidence of each of these variables in these children.

METHODS

Following a data base review, 42 children between the ages of 3 and 15 years were found to have been referred over a 10 year period. The body mass index was assessed. The cross sectional areas and circumferences of the venous sinuses were measured at 4 levels to calculate the hydraulic and effective diameters. The arterial inflow, sagittal and straight sinus outflows were measured. Automatic cerebral volumetry allowed the brain volume and cerebral blood flow (CBF) to be calculated. The optic nerve sheath diameter was used as a surrogate marker of raised intracranial pressure (ICP). The sagittal sinus percentage venous return was used as a surrogate marker of elevated venous pressure. Age and sex matched control groups were used for comparison.

RESULTS

Compared to controls, the obesity rates were not significantly different in this cohort. Compared to controls, those at risk for IIH had a 17% reduction in transverse sinus and 14% reduction in sigmoid sinus effective cross sectional area (p = 0.005 and 0.0009). Compared to controls, the patients at risk for IIH had an arterial inflow increased by 34% (p < 0.0001) with a 9% larger brain volume (p = 0.02) giving an increase in CBF of 22% (p = 0.005). The sagittal and straight sinus venous return were reduced by 11% and 4% respectively (p < 0.0001 and 0.0009) suggesting raised venous sinus pressure. Forty five percent of the patients were classified as hyperemic and these had optic nerve sheath diameters 17% larger than controls (p < 0.0002) suggesting raised ICP.

CONCLUSION

In children with the chronic headache/ IIH spectrum, the highest associations were with cerebral hyperemia and mild venous sinus stenosis. Obesity was not significantly different in this cohort. There is evidence to suggest hyperemia increases the venous sinus pressure and ICP.

Correlation between the total number of features of paediatric pseudotumour cerebri syndrome and cerebrospinal fluid pressure

PURPOSE

Accurate diagnosis of pseudotumour cerebri syndrome (PTCS) in children is challenging. We aimed to see if the clinical and radiological assessment that is carried out before lumbar puncture could predict subsequently recorded CSF pressures, and thus whether it could be used to increase diagnostic certainty of paediatric PTCS.

METHODS

We used internationally recognised diagnostic criteria to derive a list of clinical, brain neuroimaging and venography features that were accepted to be associated with a diagnosis of PTCS. We performed a retrospective cohort study of children referred to our centre with suspected PTCS, identifying the presence or absence of those features for each child at initial presentation. The sum total scores of the features that were present were correlated with the child's recorded CSF pressure.

RESULTS

The sum total scores were significantly positively correlated with recorded CSF pressures. The positive correlation was seen when clinical and brain neuroimaging features were included alone, and the correlation was slightly stronger when venography features were included in addition.

CONCLUSION

Calculating the sum total of clinical, brain neuroimaging and venography features (where venography is performed) present at initial presentation can help in the management of children under investigation for PTCS. Children with high scores are more likely to have severely raised CSF pressures and thus may warrant more urgent LP investigations. By contrast, in children with subtle abnormalities in optic disc appearance such that disc oedema cannot be ruled out, a low score may add further reassurance and less urgency to proceed to LP.

The incidence of significant venous sinus stenosis and cerebral hyperemia in childhood hydrocephalus: prognostic value with regards to differentiating active from compensated disease

BACKGROUND

Symptomatic or active hydrocephalus in children is linked to an elevation in intracranial pressure (ICP), which is likely to be multifactorial in origin. The CSF outflow resistance, venous sinus resistance and total cerebral blood flow are likely factors in the ICP elevation. The purpose of this paper is to define the incidence, site and significance of venous sinus stenosis and/or cerebral hyperemia in a cohort of children diagnosed with hydrocephalus at a tertiary referral hospital.

METHODS

The imaging database was reviewed over a 10 year period and the index MRI of all children between the ages of 4 months and 15 years, who were diagnosed with treatment naive hydrocephalus of any type (excluding secondary to tumor) and had magnetic resonance venography (MRV) and flow quantification were selected. Patients were compared with children undergoing an MRI with MRV and flow quantification who were subsequently shown to have no abnormality. The cross-sectional area and circumference of the sinuses were measured at 4 levels. The hydraulic and effective diameters were calculated. An area stenosis of 65% or greater was deemed significant. A total cerebral blood flow greater than two standard deviations above the mean for controls was taken to be abnormal.

RESULTS

There were a total of 55 children with hydrocephalus compared to 118 age matched control MRV's and 35 control flow quantification studies. A high grade stenosis occurred in 56% of patients but in none of the controls (p < 0.0001). The commonest site of narrowing was in the distal sigmoid sinus. Cerebral hyperemia occurred in 13% of patients but did not occur in the controls.

CONCLUSIONS

The elevation in ICP in symptomatic hydrocephalus is multifactorial. Both high grade venous stenosis and cerebral hyperemia are common in childhood hydrocephalus. High grade stenosis was noted to be a risk factor for conservative management failure. Hyperemia was a good prognostic indicator.

Slit Ventricle as a Neurosurgical Emergency: Case Report and Review of Literature

BACKGROUND

Symptomatic slit ventricle is one of the most challenging complications of shunt surgery in children. Clinical signs and symptoms may appear with a wide range of intracranial pressure (ICP) values. We report the case of a 10-year-old girl, who did not present the classic clinical features of extremely elevated ICP, which was proven by multiple invasive ICP recordings, performed during shunt revisions.

CASE DESCRIPTION

At the age of 6 months, the patient presented squeal for many hours, accompanied with sunset eyes, bulging anterior fontanel, and dilated ventricles of all 4 ventricles on computed tomography scan. Acute ventriculoperitoneal shunt insertion was performed with adjustable valve. During the following 9 years, she was regularly seen and medically treated for intermittent headache, with nausea and vomiting. From 9 years of age, she was hospitalized for severe (10/10 on the visual analog scale), unbearable headache, agitation, and screaming on multiple occasions. Altogether, we had to revise the shunt system 5 times throughout 1 year. Radiologic imaging always showed narrow ventricles. Ophthalmologic examination of the fundus never revealed signs of raised ICP. Perioperative monitoring of the ICP with intraparenchymal sensor showed unexpected high values of 40-45 mm Hg. However, repetitive shunt revisions were successful only temporarily because the symptoms always returned. Only bilateral shunting of the ventricular system was able to eliminate the symptoms permanently.

CONCLUSIONS

Images of slit ventricle can be associated either with low or extremely high ICP needing urgent surgical consideration, including ICP monitoring. Bilateral shunt insertion can be effective treatment for slit ventricle syndrome.

High Intracranial Pressure Induced Injury in the Healthy Rat Brain

OBJECTIVES

We recently showed that increased intracranial pressure to 50 mm Hg in the healthy rat brain results in microvascular shunt flow characterized by tissue hypoxia, edema, and increased blood-brain barrier permeability. We now determined whether increased intracranial pressure results in neuronal injury by Fluoro-Jade stain and whether changes in cerebral blood flow and cerebral metabolic rate for oxygen suggest nonnutritive microvascular shunt flow.

DESIGN

Intracranial pressure was elevated by a reservoir of artificial cerebrospinal fluid connected to the cisterna magna. Arterial blood gases, cerebral arterial-venous oxygen content difference, and cerebral blood flow by MRI were measured. Fluoro-Jade stain neurons were counted in histologic sections of the right and left dorsal and lateral cortices and hippocampus.

SETTING

University laboratory.

SUBJECTS

Male Sprague Dawley rats.

INTERVENTIONS

Arterial pressure support if needed by IV dopamine infusion and base deficit corrected by sodium bicarbonate.

MEASUREMENTS AND MAIN RESULTS

Fluoro-Jade stain neurons increased 2.5- and 5.5-fold at intracranial pressures of 30 and 50 mm Hg and cerebral perfusion pressures of 57 ± 4 (mean ± SEM) and 47 ± 6 mm Hg, respectively (p < 0.001) (highest in the right and left cortices). Voxel frequency histograms of cerebral blood flow showed a pattern consistent with microvascular shunt flow by dispersion to higher cerebral blood flow at high intracranial pressure and decreased cerebral metabolic rate for oxygen.

CONCLUSIONS

High intracranial pressure likely caused neuronal injury because of a transition from normal capillary flow to nonnutritive microvascular shunt flow resulting in tissue hypoxia and edema, and it is manifest by a reduction in the cerebral metabolic rate for oxygen.

Quantitative imaging biomarkers for dural sinus patterns in idiopathic intracranial hypertension

OBJECTIVE

To quantitatively characterize transverse dural sinuses (TS) on magnetic resonance venography (MRV) in patients with idiopathic intracranial hypertension (IIH), compared to healthy controls, using a computer assisted detection (CAD) method.

MATERIALS AND METHODS

We retrospectively analyzed MRV studies of 38 IIH patients and 30 controls, matched by age and gender. Data analysis was performed using a specially developed Matlab algorithm for vessel cross-sectional analysis. The cross-sectional area and shape measurements were evaluated in patients and controls.

RESULTS

Mean, minimal, and maximal cross-sectional areas as well as volumetric parameters of the right and left transverse sinuses were significantly smaller in IIH patients than in controls (p < .005 for all). Idiopathic intracranial hypertension patients showed a narrowed segment in both TS, clustering near the junction with the sigmoid sinus. In 36% (right TS) and 43% (left TS), the stenosis extended to >50% of the entire length of the TS, i.e. the TS was hypoplastic. Narrower vessels tended to have a more triangular shape than did wider vessels.

CONCLUSION

Using CAD we precisely quantified TS stenosis and its severity in IIH patients by cross-sectional and volumetric analysis. This method can be used as an exact tool for investigating mechanisms of IIH development and response to treatment.

Osteoblastoma Mimicking an Idiopathic Intracranial Hypertension Syndrome

Osteoblastomas are rare, benign bone tumors mainly arising from the long bones and the posterior vertebral arches. Skull localizations account for approximately 15% of cases. A total amount of thirty cases involving the temporal bone are reported in the literature. Clinical presentation of temporal osteoblastomas often includes local pain and swelling, while 7^th and 8^th cranial nerve impairment is rare. We report the novel finding of increase intracranial pressure syndrome secondary to dominant transverse-sigmoid sinus junction compression caused by a small temporal bone osteoblastoma. Excision of the tumor with the restoration of venous flow in the sigmoid sinus was followed by a prompt clinical improvement. In the management of patients with a venous sinus compression, restoration of venous drainage should be a priority.

Lateral Sinus Thrombosis: The Importance of the Unaffected Sinus

BACKGROUND AND PURPOSE

Intracranial hypertension develops in only some patients with lateral sinus thrombosis (LST), for reasons that are unclear. The purpose of this study was to evaluate a possible association between patency of the unaffected sinus and clinical presentation of unilateral LST.

METHODS

A computerized search identified patients with LST, hospitalized in Soroka Medical Center. Patients with signs of increased intracranial pressure (iICP) and those with normal intracranial pressure (nICP) were compared. CT venography or MR venography confirmed the diagnosis, located the thrombosis, and determined the dominant lateral sinus (LS). Diameters of the right and left LSs (the occluded and unaffected) were compared to the diameter of the distal superior sagittal sinus (SSS).

RESULTS

Of the 50 patients identified, 30 had iICP and 20 nICP. The dominant LS was the right one in 39 (78%) and the left one in 8 (16%); 3 (6%) had equal LS dominance. The dominant sinus was affected in 32 (70%) and the non-dominant in 15 (30%) patients. iICP was detected in 28/32 (81%) of patients with the dominant side affected, and 3/15 (20%) of those with non-dominant thrombotic sinus (P = .002). The unaffected sinus was narrower in iICP patients (size relative to SSS diameter = 43% in iICP vs. 86% in nICP [P = .0002]; size grading, according to Farb's method was 1.86 in the iICP vs. 3.57 in the nICP group [P = .0001]).

CONCLUSIONS

Thrombosis was more common in the dominant LS. Unaffected LS patency appears to be associated with the development of increased ICP.

Incidence and predictors of dural venous sinus pressure gradient in idiopathic intracranial hypertension and non-idiopathic intracranial hypertension headache patients: results from 164 cerebral venograms

OBJECTIVE Cerebral venous pressure gradient (CVPG) from dural venous sinus stenosis is implicated in headache syndromes such as idiopathic intracranial hypertension (IIH). The incidence of CVPG in headache patients has not been reported. METHODS The authors reviewed all cerebral venograms with manometry performed for headache between January 2008 and May 2015. Patient demographics, headache etiology, intracranial pressure (ICP) measurements, and radiographic and manometric results were recorded. CVPG was defined as a difference ≥ 8 mm Hg by venographic manometry. RESULTS One hundred sixty-four venograms were performed in 155 patients. There were no procedural complications. Ninety-six procedures (58.5%) were for patients with IIH. The overall incidence of CVPG was 25.6% (42 of 164 procedures): 35.4% (34 of 96 procedures) in IIH patients and 11.8% (8 of 68 procedures) in non-IIH patients. Sixty procedures (36.6%) were performed in patients with preexisting shunts. Seventy-seven patients (49.7%) had procedures preceded by an ICP measurement within 4 weeks of venography, and in 66 (85.7%) of these patients, the ICP had been found to be elevated. CVPG was seen in 8.3% (n = 5) of the procedures in the 60 patients with a preexisting shunt and in 0% (n = 0) of the 11 procedures in the 77 patients with normal ICP (p < 0.001 for both). Noninvasive imaging (MR venography, CT venography) was assessed prior to venography in 112 (68.3%) of 164 cases, and dural venous sinus abnormalities were demonstrated in 73 (65.2%) of these cases; there was a trend toward CVPG (p = 0.07). Multivariate analysis demonstrated an increased likelihood of CVPG in patients with IIH (OR 4.97, 95% CI 1.71-14.47) and a decreased likelihood in patients with a preexisting shunt (OR 0.09, 95% CI 0.02-0.44). CONCLUSIONS CVPG is uncommon in IIH patients, rare in those with preexisting shunts, and absent in those with normal ICP.

Focal stenosis of the sigmoid sinus causing intracranial venous hypertension: Case report, endovascular management, and review of the literature

Regardless of the underlying pathology, elevated intracranial pressure is the endpoint of any impairment in either cerebrospinal fluid (CSF) absorption (including arachnoid villi) or intracranial venous drainage. In all age groups, the predominant final common pathway for CSF drainage is the dural venous sinus system. Intracranial venous hypertension (ICVH) is an important vascular cause of intracranial hypertension (and its subsequent sequelae), which has often been ignored due to excessive attention to the arterial system and, specifically, arteriovenous shunts. Various anatomical and pathological entities have been described to cause ICVH. For the second time, we present a unique case of severe focal stenosis in the distal sigmoid sinus associated with concurrent hypoplasia of the contralateral transverse sinus causing a significant pressure gradient and intracranial hypertension, which was treated with endovascular stent placement and angioplasty.

Venous sinus stenting for idiopathic intracranial hypertension is not associated with cortical venous occlusion

Background

The effect of dural venous sinus stenting has been investigated for the treatment of idiopathic intracranial hypertension (IIH) but the effect of stenting on the long-term patency of the cortical draining veins, especially the vein of Labbé (VOL), remains unknown.

Methods

We reviewed our database of 38 patients with IIH with 41 stented dural venous sinuses between October 2006 and December 2014. Demographic, clinical, and radiological data were reviewed. Follow-up catheter angiographic data were included when available.

Results

Stent placement spanned the ostium of the VOL in 35 patients (92.1%), with no immediate effect on the drainage of the VOL. Follow-up angiography (mean 35.1 months, range 1.7–80.7 months) was available in 24 patients, 21 of whom had stents spanning the VOL ostium. The VOL remained patent without occlusion or drainage alteration in all 21 patients. There were no immediate or long-term intracranial complications.

Conclusions

Dural venous sinus stenting for patients with IIH does not affect the immediate or long-term patency of the VOL and is not associated with intracranial complications.

Fifteen-minute consultation: the child with idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a rare condition where intracranial hypertension is found in the context of normal brain parenchyma and no mass lesion, ventriculomegaly, underlying infection, or malignancy. Our understanding of this condition has greatly improved in the recent years with neuroimaging features and normal values for lumbar puncture opening pressure now well defined. This article provides a review of IIH in children and revised diagnostic criteria based on recent evidence and published opinion. We have also presented an algorithmic approach to the child with possible IIH.

The Pseudotumor Cerebri Syndrome: A Unifying Pathophysiological Concept for Patients with Isolated Intracranial Hypertension with Neither Mass Lesion Nor Ventriculomegaly

In 1991 we proposed that while the syndrome of isolated intracranial hypertension might have many definite and probable causes, it has nonetheless a single unifying pathophysiological mechanism: namely, impairment of cerebrospinal fluid (CSF) reabsorption. For that reason, we also proposed then that it is best described by a single, unifying, inclusive term, namely, pseudotumor cerebri syndrome. Although it appears that there is, as far as nomenclature is concerned, now international agreement, there is as yet no agreement on pathophysiology and classification. Herein we outline our views on these matters and give our reasons.

Hypertensive slit ventricle syndrome: pseudotumor cerebri with a malfunctioning shunt?

Symptomatic shunt malfunction without ventricular enlargement is known as slit ventricle syndrome (SVS). Patients presenting with this syndrome are not a homogeneous group. Of the 5 different types classified by Rekate, Type 1 is caused by CSF overdrainage and is associated with low pressures; Types 2 and 3 are associated with shunt blockage and elevated CSF pressures; Type 4 is cephalocranial disproportion that increases brain parenchymal pressure but not CSF pressure; and Type 5 is headache unrelated to shunt function. The low and normal CSF pressure types are relatively well understood, but the high-pressure forms are more problematic. In the high-pressure forms of SVS it is said that the lack of ventricular dilation is related to a reduction in brain compliance analogous to idiopathic intracranial hypertension or pseudotumor cerebri. Despite this, there is little evidence in the literature to support this conjecture. With this in mind, 3 cases of SVS associated with elevated CSF pressure are presented. The MR venogram findings and hemodynamics of these 3 cases are shown to be identical to those of pseudotumor cerebri. A literature review indicates that an underlying venous impairment may be functioning in the patients who re-present with small ventricles following shunt malfunction.