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

Imaging of Pulsatile Tinnitus

Tinnitus is a common complaint that approximately three-fourths of adults will experience at some point in their life. While for many it is a mild nuisance, for some it can be debilitating, affecting cognition and quality of life, increasing stress, and leading to anxiety, depression, and in severe circumstances even suicide. Pulsatile tinnitus refers to the perception of a heartbeat-like sound without external stimulus. Although less common than nonpulsatile tinnitus, pulsatile tinnitus raises concern for underlying disease that can have a high risk of causing the patient harm if undiagnosed, and most of these patients will have positive findings at imaging. While these findings are often subtle, identifying them can have a meaningful impact on the patient's quality of life. The literature on pulsatile tinnitus is changing rapidly with improved imaging techniques and novel minimally invasive treatment options. A careful history and physical examination together with appropriate imaging are therefore critical in identifying the underlying cause. With emerging surgical, endovascular, and supportive technologies, the vast majority of patients with bothersome pulsatile tinnitus can be cured or have their symptoms ameliorated. The objective of this narrative review is to present a comprehensive analysis of the currently available literature on pulsatile tinnitus, with a focus on understanding its pathophysiologic mechanisms, diagnostic pathways, imaging findings, and the spectrum of available management strategies and ultimately to propose a structured framework that aids radiologists as well as clinicians in identifying an underlying diagnosis and guiding management of these patients. ©RSNA, 2024 Supplemental material is available for this article.

Analysis of cerebral venous sinus stenosis by flat panel angiographic CT (FP-CT) to guide treatment for idiopathic intracranial hypertension

INTRODUCTION

Cerebral venous sinus stenting (CVSS) is an effective treatment for idiopathic intracranial hypertension (IIH) secondary to dural venous sinus stenosis. Traditional selection of patients for CVSS has been made by microcatheter manometry, but pressure measurements are often equivocal. Here we present the results of a series of cases in which venous flat-panel CT (FP-CT) was used as an adjunct to microcatheter manometry to improve decision making and precise stent placement during CVSS.

METHODS

Ten consecutive patients with IIH underwent angiography with microcatheter manometry and venous FP-CT, with CVSS if indicated by the results. Cross-sectional measurements of the narrowed sinus were obtained on FP-CT before and after stenting. After the procedure, clinical outcomes were tracked. Follow-up with quantitative MRA with sinus flow measurements was also performed, when available.

RESULTS

There was an exponential correlation between measured pressure gradient and degree of stenosis calculated using venous FP-CT. All patients with both a high degree of stenosis measured by FP-CT and a high pressure gradient across the stenosis showed a clinical benefit from stenting.

CONCLUSIONS

True measurement of the cross-sectional area of the dural sinus, made by venous phase FP-CT, has a high degree of correlation with elevated venous pressure gradient across the point of stenosis. Even in a limited series of cases, we found an exponential decrease in flow with increasing severity of stenosis. Furthermore, patients with both an elevated venous pressure gradient and critical stenosis of the sinus on FP-CT showed symptomatic improvement after stenting.

Safety of intracranial venous stenting in patients with nickel allergy

BACKGROUND

Nickel hypersensitivity is the most common metal related allergy. Nickel containing alloys are frequently used in endovascular devices. The use of intracranial stents in patients with nickel hypersensitivity appears to be safe, but these small series only evaluated arterial stent placement. This case series aimed to assess the safety of intracranial venous stent placement in patients with documented nickel allergy.

METHODS

In this retrospective multicenter case series, patients with idiopathic intracranial hypertension and documented nickel allergy underwent treatment with a permanently implanted nickel containing stent in the dural venous sinuses.

RESULTS

Nine patients with nickel allergy were included. All patients reported clinical improvement in their idiopathic intracranial hypertension symptoms. Of the five patients who had follow-up intracranial venous imaging, all stents remained patent. No patients experienced intraoperative, postoperative, or long term procedure related complications, with follow-up ranging from 1.8 weeks to 49.1 months.

CONCLUSION

In this limited case series, the use of nickel containing stents in intracranial venous sinuses in patients with nickel allergy did not result in any allergic reaction or adverse outcome.

Blood Flow Velocity: a Decision Tool for Stenting Indication in Venous Pulsatile Tinnitus

BACKGROUND AND PURPOSE

Lateral sinus stenosis is the most common cause of venous pulsatile tinnitus (VPT). Stenting is an effective treatment after demonstration of a trans-stenotic pressure gradient; however, pressure measurement has many technical limitations. In 2018, a study showed that a combined approach with intravascular velocity measurement could be effective in identifying most appropriate candidates for stenting. The aim of the present study was to evaluate a new strategy using this biomarker for the indication of stenting even without a significant pressure gradient.

MATERIAL AND METHODS

Consecutive patients with disabling VPT were included from 2016 to 2019 and analyzed retrospectively. Intrasinusal pressures were measured and blood flow velocities (with a dual-sensor guidewire) were used for the indication of stenting independent of the pressure gradient. We evaluated the clinical outcome after stenting based on this new biomarker.

RESULTS

A total of 41 patients were treated according to this strategy. At last follow-up (mean = 30.2 months), 32/33 patients (97%) treated by stenting showed complete resolution or a significant decrease in VPT intensity. The use of velocity as the threshold for indicating stenting identified 8 patients (24%) missed by the pressure gradient. Their clinical outcome after stenting was excellent and no complications occurred.

CONCLUSION

Measurement of sinus blood flow velocity provides a hemodynamic explanation of disease and may be a better tool than pressure gradient for the indication of stenting in VPT.

A scoping review of the discrepancies in the measurement of cerebral blood flow in idiopathic intracranial hypertension: oligemia, euvolemia or hyperemia?

BACKGROUND

The literature regarding the global cerebral blood flow (CBF) in idiopathic intracranial hypertension (IIH) is divergent leading to skepticism about the significance of blood flow to the disease's underlying pathophysiology.

METHODS

The purpose of the current paper is to perform a PRISMA scoping review of the literature describing the CBF in IIH. The review investigated the PUBMED and Scopus data bases looking at case mix, technique and the methodologies employed by the studies selected.

DISCUSSION

Many studies indicate that the flow in IIH is normal but others show the flow to be altered. These later studies show a range of flows from a reduction of 20% to an increase of 50% compared to control values. Obesity is a common finding in IIH and is known to reduce CBF, anemia occurs in approximately 20% of IIH patients and is a potent cause of an increased CBF. Thus, variations in case mix may have a significant effect on the final outcome in those studies which are underpowered. The varying techniques which have been used to estimate CBF have differing strengths and weaknesses which may also have a bearing on the outcome. Some papers have significant confounding methodological issues.

CONCLUSIONS

This review suggests each of the variables investigated are responsible for the divergent CBF findings in IIH.

Venous Sinus Stenting for Low Pressure Gradient Stenoses in Idiopathic Intracranial Hypertension

BACKGROUND

Medically refractory idiopathic intracranial hypertension (IIH) is frequently treated with venous sinus stenosis stenting with high success rates. Patient selection has been driven almost exclusively by identification of supraphysiological venous pressure gradients across stenotic regions based on theoretical assessment of likelihood of response.

OBJECTIVE

To explore the possibility of benefit in low venous pressure gradient patients.

METHODS

Using a single-center, prospectively maintained registry of patients with IIH undergoing venous stenting, we defined treatment groups by gradient pressures of ≤4, 5 to 8, and >8 mmHg based on the most frequently previously published thresholds for stenting. Baseline demographics, clinical, and neuro-ophthalmological outcomes (including optical coherence tomography and Humphrey visual fields) were compared.

RESULTS

Among 53 patients, the mean age was 32 years and 70% female with a mean body mass index was 36 kg/m 2 . Baseline characteristics were similar between groups. The mean change in lumbar puncture opening pressure at 6 months poststenting was similar between the 3 groups (≤4, 5-8, and >8 mmHg; 13.4, 12.9, and 12.4 cmH 2 O, P = .47). Papilledema improvement was observed across groups at 6 months (100, 93, and 86, P = .7) as were all clinical symptoms. The mean changes in optical coherence tomography retinal nerve fiber layer (-30, -54, and -104, P = .5) and mean deviation in Humphrey visual fields (60, 64, and 67, P = .5) at 6 weeks were not significantly different.

CONCLUSION

Patients with IH with low venous pressure gradient venous sinus stenosis seem to benefit equally from venous stenting compared with their higher gradient counterparts. Re-evaluation of our restrictive criteria for this potentially vision sparing intervention is warranted. Future prospective confirmatory studies are needed.

Cerebrospinal Fluid Shunting for Idiopathic Intracranial Hypertension: A Systematic Review, Meta-Analysis, and Implications for a Modern Management Protocol

BACKGROUND

Cerebrospinal fluid (CSF) shunting is widely used in refractory idiopathic intracranial hypotension (IIH). Although multiple reviews have assessed its efficacy compared with other surgical treatments, there is no detailed analysis that evaluates the clinical outcomes after CSF shunting.

OBJECTIVE

To conduct a meta-analysis of the clinical impact of CSF shunting for refractory IIH and use this in conjunction with existing information on other treatment modalities to develop a modern management protocol.

METHODS

PubMed and Embase were systematically searched for studies describing CSF shunting for medically refractory IIH. Relevant information including study characteristics, patient demographics, clinical outcomes, periprocedural complications, and long-term outcomes were subjected to meta-analysis.

RESULTS

Fifteen studies published between 1988 and 2019 met our inclusion and exclusion criteria, providing 372 patients for analysis. The mean age was 31.2 years (range 0.5-71) with 83.6% being female. The average follow-up was 33.9 months (range 0-278 months). The overall rate of improvement in headache, papilledema, and visual impairment was 91% (95% CI 84%-97%), 96% (95% CI 85%-100%), and 85% (95% CI 72%-95%), respectively. Of 372 patients, 155 had 436 revisions; the overall revision rate was 42% (95% CI 26%-59%). There was no significant correlation between average follow-up duration and revision rates in studies ( P = .627). Periprocedural low-pressure headaches were noted in 74 patients (20%; 95% CI 11%-32%).

CONCLUSION

CSF shunting for IIH is associated with significant improvement in clinical symptoms. Shunting rarely causes periprocedural complications except overdrainage-related low-pressure headache. However, CSF shunting has a relatively high revision rate.

Idiopathic intracranial hypertension imaging approaches and the implications in patient management

Idiopathic intracranial hypertension (IIH) represents a clinical disease entity without a clear etiology, that if left untreated, can result in severe outcomes, including permanent vision loss. For this reason, early diagnosis and treatment is necessary. Historically, the role of cross-sectional imaging has been to rule out secondary or emergent causes of increased intracranial pressure, including tumor, infection, hydrocephalus, or venous thrombosis. MRI and MRV, however, can serve as valuable imaging tools to not only rule out causes for secondary intracranial hypertension but can also detect indirect signs of IIH resultant from increased intracranial pressure, and demonstrate potentially treatable sinus venous stenosis. Digital subtraction venographic imaging also plays a central role in both diagnosis and treatment, providing enhanced anatomic delineation and temporal flow evaluation, quantitative assessment of the pressure gradient across a venous stenosis, treatment guidance, and immediate opportunity for endovascular therapy. In this review, we discuss the multiple modalities for imaging IIH, their limitations, and their contributions to the management of IIH.

Improved Ophthalmic Outcomes Following Venous Sinus Stenting in Idiopathic Intracranial Hypertension

Background

Ophthalmic outcomes following venous sinus stenting (VSS) in patients with idiopathic intracranial hypertension (IIH) are not well characterized.

Materials and Methods

A retrospective chart review was conducted on 86 consecutive patients with IIH who underwent venous sinus stenting at Mayo Clinic, Rochester, Minnesota and Stanford Medical Center, Palo Alto, California between May 2015 and October 2021. Patients with raised intracranial pressure from a non-IIH etiology were excluded. Clinical symptoms and neuro-ophthalmological data, including best corrected visual acuity (BCVA), visual field mean deviation, papilledema, and optical coherence tomography (OCT) peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell inner plexiform layer (GC-IPL), were analyzed. Baseline measurements before VSS and 3 months or more postoperatively were compared.

Results

Eighty-six subjects (82 female) were included in this study, with a median age of 33 (16-68) years and a median body mass index of 36.69 (22.30-62.00) kg/m2. 85/86 (98.8%) had attempted prior management with medication, and 12/86 (14%) had prior surgical management with optic nerve sheath fenestration, ventriculoperitoneal shunt, or bariatric surgery. Prior to VSS, 67/86 (77.9%) had papilledema, 85/86 (98.8%) had headaches, and 68/86 (79.1%) had pulsatile tinnitus. For patients with both pre- and post-VSS data available, the average papilledema grade was 1.76 (0-5) (n = 74) and the average OCT pRNFL was 186.34 (52.00-588.00) µm (n = 70), prior to VSS. A median of 4.0 (interquartile range 3.3-5.4) months after VSS, the average papilledema grade improved to 0.39 (0-2), p <0.001, and OCT pRNFL improved to 96.86 (47.00-168.00) µm, p <0.001. 28/86 (32.6%) patients no longer required medication for high intracranial pressure. 14/85 (16.5%) patients reported complete resolution of their headache and 55/71 (77.5%) reported improvement in headache quality. 40/68 (66.7%) reported complete resolution of pulsatile tinnitus. OCT GC-IPL, BCVA, and visual field mean deviation did not significantly change pre- vs post-VSS.

Conclusions

Our large consecutive case series corroborates smaller prior studies in demonstrating the overall efficacy of VSS for patients with IIH. We found both ophthalmic improvements, as demonstrated by the significantly reduced papilledema and pRNFL, and overall clinical symptom improvement.

Cerebral Venous Outflow Implications in Idiopathic Intracranial Hypertension-From Physiopathology to Treatment

In this review, we provide an update on the pathogenesis, diagnosis, and management of adults with idiopathic intracranial hypertension (IIH) and implications of the cerebral venous system, highlighting the progress made during the past decade with regard to mechanisms of the venous outflow pathway and its connection with the cerebral glymphatic and lymphatic network in genesis of IIH. Early diagnosis and treatment are crucial for favorable visual outcomes and to avoid vision loss, but there is also a risk of overdiagnosis and misdiagnosis in many patients with IIH. We also present details about treatment of intracranial hypertension, which is possible in most cases with a combination of weight loss and drug treatments, but also in selected cases with surgical interventions such as optic nerve sheath fenestration, cerebral spinal fluid (CSF) diversion, or dural venous sinus stenting for some patients with cerebral venous sinus stenosis, after careful analysis of mechanisms of intracranial hypertension, patient clinical profile, and method risks.

Posterior fossa volume in idiopathic intracranial hypertension: a magnetic resonance imaging-based study

BACKGROUND

The etiology of idiopathic intracranial hypertension (IIH) is uncertain. Studies suggest the fundamental cause of the Chiari 1 malformation, a congenitally hypoplastic posterior fossa, may explain the genesis of IIH in some patients.

PURPOSE

To assess the hypothesis that linear and volumetric measurements of the posterior fossa (PF) can be used as predictors of IIH.

MATERIAL AND METHODS

A retrospective analysis of magnetic resonance imaging (MRI) studies on 27 patients with IIH and 14 matched controls was performed. A volumetric sagittal magnetization prepared rapid acquisition gradient echo sequence was used to derive 10 linear cephalometric measurements. Total intracranial and bony posterior fossa volumes (PFVs) were derived by manual segmentation. The ratio of PFV to total intracranial volume was calculated.

RESULTS

In total, 41 participants were included, all women. Participants with IIH had higher median body mass index (BMI). No significant differences in linear cephalometric measurements, total intracranial volumes, and PFVs between the groups were identified. Linear measurements were not predictive of volumetric measurements. However, on multivariate logistic regression analysis, the likelihood of IIH decreased significantly per unit increase in relative PFV (odds ratio [OR]=3.66 × 10^-50; 95% confidence interval [CI]=1.39 × 10^-108 to 1.22 × 10^-5; P = 0.04). Conversely, the likelihood of IIH increased per unit BMI increase (OR=1.19; 95% CI=1.04-1.47; P = 0.02).

CONCLUSION

MRI-based volumetric measurements imply that PF alterations may be partly responsible for the development of IIH and Chiari 1 malformations. Symptoms of IIH may arise due to an interplay between these and metabolic, hormonal, or other factors.

The Relationships Among Transverse Sinus Stenosis Measured by CT Venography, Venous Trans-stenotic Pressure Gradient and Intracranial Pressure in Patients With Unilateral Venous Pulsatile Tinnitus

Objectives

To assess a non-invasive means of predicting a venous trans-stenotic pressure gradient (TPG) and intracranial pressure (ICP) as opposed to invasive examinations in unilateral venous pulsatile tinnitus (PT) patients.

Methods

Thirty patients with unilateral venous PT who presented symptomatic-sided transverse sinus stenosis (TSS) on computed tomography venography (CTV), ipsilateral TPG measured by digital subtraction angiography (DSA) and cerebrospinal fluid (CSF) pressure measured by lumbar puncture were included. The ratio of TSS was calculated by dividing the cross-sectional areas of the maximal stenosed transverse sinus by that of the adjacent normal transverse sinus on CTV. The correlations among and predictive values of TSS, TPG, and ICP were analyzed.

Results

In patients with unilateral venous PT, the symptomatic-sided and average bilateral TSS values were 78 ± 11 and 77 ± 9%; ICP, 230.50 ± 55.75 mmH₂O; and the TPG, 9.51 ± 5.76 mmHg. The symptomatic-sided TSS was linearly and positively correlated with TPG (R² = 0.400), and the symptomatic-sided and bilateral average TSS both showed weak correlations with ICP (R² = 0.288, R′² = 0.156). When the degree of TSS increased by 10%, the TPG and ICP increased by approximately 3.3 mmHg and 25.8 mmH₂O, respectively. The receiver operating characteristic curve showed the optimal threshold of ipsilateral TSS for a positive TPG was 0.75, while TSS had no significant predictive value for ICP (p > 0.05). TPG and ICP also exhibited a linear positive correlation (R² = 0.552). When ICP increased by 10 mmH₂O, the TPG increased by approximately 0.77 mmHg, and the optimal threshold of ICP for a positive TPG was 227.5.

Conclusion

TSS, TPG, and ICP are interrelated. TSS measured by CTV can predict TPG in patients with unilateral venous PT.

Venous Causes of Pulsatile Tinnitus: Clinical Presentation, Clinical and Radiographic Evaluation, Pathogenesis, and Endovascular Treatments: A Literature Review

Tinnitus is an abnormal perception of a sound without external stimulation. Venous pulsatile tinnitus (VPT) is a specific form of tinnitus characterized by an objective and often subjective bruit that occurs as a result of localized venous abnormalities. Clinical evaluation relies on sound quality, duration, and precipitating factors. Idiopathic intracranial hypertension (IIH) and transverse sinus stenosis (TSS) are among the most common causes of VPT. Other causes include sigmoid sinus wall abnormalities (SSWAs), jugular vein anomalies (JVAs), and emissary veins anomalies. These anomalies can be detected on magnetic resonance imaging, magnetic resonance angiography/magnetic resonance venography, and high-resolution temporal bone computed tomography. The pathogenesis behind the VPT includes turbulent blood flow as a result of luminal stenosis or abnormal dilation, amplification of internal sound due to temporal bone defects, and abnormal position of the venous sinus system structures adjacent to the bony structures of the auditive apparatus. Based on these theories, different interventional treatment modalities can be applied to treat the underlying causes. Endovascular treatments have shown high efficacy and safety among those treatments which include stenting of the lateral sinus stenosis in IIH and TSS, coiling of the SSWA and JVA, and embolization of emissary veins anomalies. Further studies are needed to understand the natural history of these anomalies and the efficacy of treatments of VPT, which-unlike other types of tinnitus-can be cured with proper treatment.

State of the Art: Venous Causes of Pulsatile Tinnitus and Diagnostic Considerations Guiding Endovascular Therapy

Venous variants and pathologic abnormalities are the most common causes of pulsatile tinnitus. These conditions include causes of turbulence within normally located veins and sinuses, and abnormally enlarged or abnormally located veins in close transmissive proximity to the conductive auditory pathway. Such disorders include pathologic abnormalities of the lateral sinus (transverse sinus stenosis and sigmoid sinus wall anomalies), abnormalities and variants of the emissary veins, and anomalies of the jugular bulb and jugular vein. Despite being the most common causes for pulsatile tinnitus, venous variants and pathologic abnormalities are often overlooked in the workup of pulsatile tinnitus. Such oversights can result in delayed patient care and prolonged patient discomfort. Advances in both cerebrovascular imaging and endovascular techniques allow for improved diagnostic accuracy and an increasing range of endovascular therapeutic options to address pulsatile tinnitus. This review illustrates the venous causes of pulsatile tinnitus and demonstrates the associated endovascular treatment. © RSNA, 2021.

Relentless pulsatile tinnitus secondary to dural sinovenous stenosis: is endovascular sinus stenting the answer?

AIM

To assess the efficacy of endovascular venous sinus stenting (EVSS) in treating pulsatile tinnitus (PT) caused by dural venous sinus stenosis (DVSS), and to determine whether it is an adequate remedy in cases with concurrent venous anomalies.

MATERIALS AND METHODS

Seventeen patients (13 female and four male) with PT due to DVSS were treated using EVSS. The trans-stenotic pressure gradient (PG) was measured before and after stenting. The effect of stenting on the tinnitus was evaluated by questioning the patients at day 0, and at 3, 6, and 9 months after stenting.

RESULTS

Except for one patient who continued to complain of PT, all of the patients, including two with concomitant sinus diverticula, described complete resolution of the tinnitus immediately following stenting. The post-stenting PG was significantly lower than the pre-stenting PG (p<0.0001). No procedure related complications occurred and no recurrence was recorded during the follow-up period.

CONCLUSION

EVSS is a safe and successful treatment for PT due to DVSS even in cases with coexistent sinus diverticula.

Correlation between intracranial pressure and venous sinus pressures in patients undergoing cerebral venography and manometry

BACKGROUND

The pathophysiology of idiopathic intracranial hypertension (IIH) is complex but is directly related to cerebral venous hypertension. Few studies have simultaneously recorded venous sinus pressures and lumbar puncture (LP) opening pressure (OP) to understand the relationship between these factors without temporal confounding.

METHODS

A retrospective review was performed of patients with a known or suspected diagnosis of IIH who underwent cerebral venography with manometry followed immediately by LP.

RESULTS

47 patients aged 16-68 years met inclusion criteria. 91.5% were female. Mean body mass index (BMI) was 33.3 kg/m². Of the included patients, median OP was 21 cm H₂O (IQR (15.5, 26.5)). Mean (SD) recorded superior sagittal sinus (SSS) and torcular pressures were 25.5 (16.5) mm Hg and 23.8 (16.6) mm Hg, respectively. Twenty patients (42.6%) were discovered to have a trans-stenosis gradient of 8 mm Hg or greater. Transverse sinus, torcula, and SSS pressures were all significantly predicted by OP. On regression analysis, torcular pressures were best predicted by OP of the three measured sites. For 17 patients with OP <20 cm H₂O (36.2%), mean (SD) SSS and torcular pressures were 13.5 (4.2) mm Hg and 15.4 (6.7) mm Hg, respectively, suggesting that normally SSS pressures should measure <18 mm Hg (80th percentile) in non-pathologic conditions.

CONCLUSIONS

This is the first study to correlate venous sinus pressures and OP in patients with IIH with LP performed directly after manometry. In 47 patients, LP OP significantly predicted transverse sinus, torcula, and SSS pressures. Torcular pressures (mm Hg) were most accurately predicted by OP (cm H₂O) in a nearly one-to-one relationship.

A descriptive study of venous sinus pressures and gradients in patients with idiopathic intracranial hypertension

Objective

To determine the relationship between normal physiologic and pathologic venous sinus pressures in patients with idiopathic intracranial hypertension (IIH), which is poorly understood.

Methods

Retrospective analysis was performed to identify patients with medically refractory IIH who were evaluated by angiography and retrograde venography with venous manometry. Patients were further subdivided into groups based on anatomic factors.

Results

104 patients met inclusion criteria for the study. In the absence of non-invasive venographic screening, 58% of patients in this series were found to have pressure gradients of ≥8 mm Hg; 93% were located near the transverse-sigmoid sinus junction. Opening pressure (OP) is strongly predictive of superior sagittal sinus (SSS) pressures (p<0.001) and also of the presence of a pressure gradient ≥8 mm Hg (p<0.001). Twenty-three percent of patients with an OP <25 had a pressure gradient ≥8 mm Hg compared with 77% of patients with an OP ≥35. Analysis of patients with OP ≤20 suggests that SSS pressures in patients without IIH should be less than 16–18 mm Hg with total cranial gradients <5 mm Hg. Across all patients, a pressure decrement of approximately 1 mm Hg occurs with progressively more caudal transition across anatomic points of measurement.

Conclusions

This study describes intracranial and extracranial venous pressure measurements and gradients in different subgroups of patients with IIH. OP is highly predictive of intracranial venous pressures and significant venous pressure gradients.

Venous Manometry as an Adjunct for Diagnosis and Multimodal Management of Intracranial Hypertension due to Meningioma Compressing Sigmoid Sinus

Intracranial venous hypertension is a rare presentation of meningiomas in the transverse-sigmoid sinus region. We describe a case of a young patient presenting with intracranial hypertension due to a meningioma causing compression of the dominant sigmoid sinus. We were able to document the cerebral venous pressure gradient across the lesion confirming our hypothesis that compression of the sigmoid sinus from the meningioma was the cause of intracranial hypertension. The patient is a 17-year-old male who presented with intracranial hypertension due to meningioma at the right dominant sigmoid sinus, which was treated by a Simpson grade IV surgical resection followed by stereotactic radiosurgery. Following treatment, his papilledema resolved and he remains symptom-free at 18 months. In conclusion, venous manometry is a useful adjunct to diagnose intracranial hypertension in non-idiopathic causes of intracranial hypertension. A multimodal management approach of intracranial hypertension due to outflow obstruction from the dominant sinus led to an excellent recovery on follow up.

Endovascular stenting for idiopathic intracranial hypertension with venous sinus stenosis

OBJECTIVES

Idiopathic intracranial hypertension (IIH) is characterized by elevated intracranial pressure of unknown etiology and venous sinus stenting may be an optional treatment. We aimed to evaluate the effects of venous sinus stenting on visual function, intracranial pressure, and trans-stenotic pressure gradient of the patients with IIH and to determine effects of baseline BMI or weight changes on subjective vision outcome and intracranial pressure.

METHODS

From July 2009 to Aug 2016, 88 eligible patients with IIH and venous sinus stenosis who underwent stenting were retrospectively studied.

RESULTS

In this study, 67 women and 21 men were included with an average age of 39.01 (18-60) years. The average BMI was 26.75 kg/m2 . Here, 66 (75.9%) patients had papilledema, 39 had impaired vision before stenting; 57 patients were followed-up, 48 (84.2%) showed significant subjective improvement or recovery in visual acuity, 4 (7.0%) patients reported no significant change in visual functions, and 5 (8.8%) suffered permanent vision loss. The cerebrospinal fluid opening pressure and trans-stenotic pressure gradient were significantly decreased postoperatively. Baseline BMI was associated with pre-and postoperative trans-stenotic pressure gradients, as well as changes in cerebrospinal fluid opening pressure. However, baseline BMI and body weight changes during follow-up were not necessarily associated with subjective visual outcomes after stenting. Stenting efficacy was limited in patients with severe preoperative optic symptoms.

CONCLUSIONS

Venous sinus stenting represented an effective treatment for resolving visual dysfunction and intracranial pressure associated with venous sinus stenosis. BMI seemed to be associated with intracranial pressure but not subjective visual outcomes after stenting.

Concurrent Venous Stenting of the Transverse and Occipito-Marginal Sinuses: An Analogy with Parallel Hemodynamic Circuits

Nonthrombotic intracranial venous occlusive disease (NIVOD) has been implicated in the pathophysiology of idiopathic intracranial hypertension (IIH) and various non-IIH headache syndromes. Endovascular stenting of stenotic, dominant transverse sinuses (TSs) may reduce trans-stenosis pressure gradients, decrease intracranial pressure, and alleviate symptoms in a subset of NIVOD patients. We present a case in which concurrent stenting of the occipito-marginal sinus obliterated the residual trans-stenosis pressure gradient across an initially stented dominant TS. We hypothesize that this observation may be explained using an electric-hydraulic analogy, and that this patient's dominant TS and occipito-marginal sinus may be modeled as a parallel hemodynamic circuit. Neurointerventionalists should be aware of parallel hemodynamic drainage patterns and consider manometry and possibly additional stenting of stenotic, parallel venous outflow pathways if TS stenting alone fails to obliterate the trans-stenosis pressure gradient.

Rebound high-pressure headache after treatment of spontaneous intracranial hypotension: MRV study

BACKGROUND

Rebound high-pressure headaches may complicate treatment of spontaneous intracranial hypotension (SIH), but no comprehensive study of such patients has been reported and little is known about its frequency and risk factors. We therefore studied patients undergoing treatment for SIH and performed magnetic resonance venography (MRV) to assess for cerebral venous sinus stenosis, a risk factor for idiopathic intracranial hypertension.

METHODS

We studied a consecutive group of patients who underwent treatment for SIH. Rebound high-pressure headache was defined as a reverse orthostatic headache responsive to acetazolamide. MRV was obtained in all patients and lateral sinus stenosis was scored according to the system published by Higgins et al., with 0 being normal and 4 signifying bilateral signal gaps.

RESULTS

The mean age of the 46 men and 67 women was 45.9 years (range 13-71 years) at the time of onset of SIH. Rebound high-pressure headache was diagnosed in 31 patients (27.4%); 14% of patients with an MRV score of 0, 24% with a score of 1, and 46% with a score of 2 or 3 (p = 0.0092). Also, compared to SIH patients who did not develop rebound high-pressure headaches (n = 82), those with rebound high-pressure headaches were younger, more often female, and more often had an extradural CSF collection on spinal imaging.

CONCLUSIONS

Rebound high-pressure headache occurs in about one-fourth of patients following treatment of SIH and is more common in those with restriction of cerebral venous outflow.

Endovascular treatment of idiopathic intracranial hypertension caused by multiple venous sinus stenoses

Background:

Idiopathic intracranial hypertension (IIH) shows symptoms by elevating intracranial pressure. Although sinus stenosis has been detected in many patients with IIH, the role of sinus stenosis in IIH remains obscure. Endovascular treatment for IIH due to transverse sinus stenosis has been frequently documented; however, IIH due to multiple sinus stenoses including the superior sagittal sinus (SSS) is rare. Here, we report a case of IIH due to multiple sinus stenoses treated by sinus stenting.

Case Presentation:

A 47-year-old woman suffered from intractable headache with IIH presented with stenosis of the right transverse and SSS. Stent placement was carried out since intracranial hypertension and trans-stenotic cerebral venous pressure gradient (CVPG) were presented, and her intractable headache disappeared.

Conclusion:

IIH can be caused by venous sinus stenoses and stent placement could be an appropriate treatment in patients who demonstrated a CVPG.

Fifty shades of gradients: does the pressure gradient in venous sinus stenting for idiopathic intracranial hypertension matter? A systematic review

OBJECTIVE

The role of venous sinus stenting (VSS) for idiopathic intracranial hypertension (IIH) is not well understood. The aim of this systematic review is to attempt to identify subsets of patients with IIH who will benefit from VSS based on the pressure gradients of their venous sinus stenosis.

METHODS

MEDLINE/PubMed was searched for studies reporting venous pressure gradients across the stenotic segment of the venous sinus, pre- and post-stent pressure gradients, and clinical outcomes after VSS. Findings are reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

RESULTS

From 32 eligible studies, a total of 186 patients were included in the analysis. Patients who had favorable outcomes had higher mean pressure gradients (22.8 ± 11.5 mm Hg vs 17.4 ± 8.0 mm Hg, p = 0.033) and higher changes in pressure gradients after stent placement (19.4 ± 10.0 mm Hg vs 12.0 ± 6.0 mm Hg, p = 0.006) compared with those with unfavorable outcomes. The post-stent pressure gradients between the 2 groups were not significantly different (2.8 ± 4.0 mm Hg vs 2.7 ± 2.0 mm Hg, p = 0.934). In a multivariate stepwise logistic regression controlling for age, sex, body mass index, CSF opening pressure, pre-stent pressure gradient, and post-stent pressure gradient, the change in pressure gradient with stent placement was found to be an independent predictor of favorable outcome (p = 0.028). Using a pressure gradient of 21 as a cutoff, 81/86 (94.2%) of patients with a gradient > 21 achieved favorable outcomes, compared with 82/100 (82.0%) of patients with a gradient ≤ 21 (p = 0.022).

CONCLUSIONS

There appears to be a relationship between the pressure gradient of venous sinus stenosis and the success of VSS in IIH. A randomized controlled trial would help elucidate this relationship and potentially guide patient selection.

Recommendations for the selection and treatment of patients with idiopathic intracranial hypertension for venous sinus stenting

INTRODUCTION

Although venous sinus stenting (VSS) has emerged as a promising treatment option for patients with idiopathic intracranial hypertension (IIH) and associated venous sinus stenosis, there is considerable ambiguity regarding patient selection criteria, treatment protocols, and management strategies.

METHODS

An extensive literature review was performed to identify all reports of VSS in patients with IIH using PubMed. Recommendations for the selection and treatment of patients with IIH with VSS are outlined as determined based on author opinion from supporting studies. Due to the lack of randomized trials and few published prospective studies, standard grading scales for recommendations and level of evidence are not fully applicable and therefore a revised grading scale has been provided for recommendations.

RESULTS

The literature review identified a total of eight systematic reviews or meta-analyses and 29 published patient series on VSS. Recommendations for patient selection for diagnostic catheter angiography, angiography procedural considerations, stenting procedural considerations, and retreatment are provided based on the literature. Recommendations that were considered strong included: performance of venous sinus manometry to assess candidacy for treatment prior to stenting; administration of antiplatelet agents prior to stenting and for a follow-up period of at least 3-6 months; performance of post-stenting manometry to confirm resolution of pressure gradient; and performance of repeat angiography and manometry on patients with recurrence of symptoms after resolution with stenting to evaluate for recurrent stenosis.

CONCLUSION

VSS for patients with IIH with venous sinus stenosis is now an established and effective treatment option. These recommendations have been provided, based on a summative review of the available published literature, to assist in standardizing care for patients with IIH undergoing VSS.

Markedly Elevated Intracranial Pressure Treated With Cranial Vault Expansion, Instead of CSF Shunting, in a Child With Hurler-Scheie Syndrome and Multiple Suture Craniosynostosis

Despite a known association of mucopolysaccharidoses (MPS) and craniosynostosis, treatment of elevated intracranial pressure (ICP) in these patients is primarily cerebrospinal fluid (CSF) shunting. We present a unique case of Hurler-Scheie syndrome with multisuture craniosynostosis and elevated ICP, without ventriculomegaly, where elevated ICP was successfully treated with extensive cranial vault expansion and shunt placement was avoided. Patients with MPS should be evaluated for craniosynostosis, and calvarial vault expansion may be considered as a viable treatment alternative to CSF shunting for elevated ICP in select patients.

Retrograde 3D rotational venography (3DRV) for venous sinus stent placement in idiopathic intracranial hypertension

Background

Dural venous sinus stenting has emerged as an effective and durable treatment for idiopathic intracranial hypertension (IIH). Improved visualization of the venous sinuses can improve stent placement.

Methods

We present two cases of IIH treated with venous sinus stenting in which retrograde three-dimensional rotational venography (3DRV) provided superior anatomical details of the venous sinuses for optimal sizing and positioning of stent.

Results

Comparison of pre-stent 3DRV with post-stent contrast-enhanced flat panel detector CT allowed confirmation of stent placement and the result of stenosis dilation.

Conclusion

This 3DRV technique provides precise visualization of venous sinus stenosis prior to stenting without the need for arterial cerebral angiography during the treatment course.

Accuracy and precision of venous pressure measurements of endovascular microcatheters in the setting of dural venous sinus stenosis

Introduction

Dural venous sinus stenosis (DVSS) may lead to increased intracranial pressure, sometimes requiring a stent if a high pressure gradient exists. Many neuroendovascular physicians use microcatheters to measure gradients, yet there are no studies comparing the accuracies and precisions of modern day microcatheters. We examined pressure recordings from five commonly used microcatheters in an experimental DVSS model.

Methods

Using a programmable pump, dynamic flow was established in a closed circuit mimicking the venous sinus waveform. Microcatheters with 150 cm effective lengths were connected proximally to pressure transducers. Mean recording pressures were compared with a high fidelity microcatheter (HFM) in several configurations including no stenosis, proximal to a focal stenosis, and distal to a focal stenosis in opposing orientations.

Results

All microcatheters recorded lower pressures than the HFM. Three of the five microcatheters successfully met intracranial pressure monitoring device standards in all conditions, while one did not meet standards in any configuration. The performance of the final microcatheter was variable, with inaccuracies occurring in unrestricted flow. All microcatheters demonstrated relatively high precision, but with variable accuracies. The larger diameter microcatheters displayed the least damping and therefore the greatest accuracies. Of the three smaller microcatheters, dimensions did not predict performance, suggesting that microcatheter construction may also play a role in pressure accuracy.

Conclusion

The use of microcatheters to record dural venous sinus pressures must be done with an understanding of the inherent limitations and inaccuracies, especially if clinical decisions are made from the results.

Idiopathic Intracranial Hypertension: Prognostic Factors and Multidisciplinary Management

BACKGROUND

Idiopathic intracranial hypertension (IIH) mostly affects young obese women and can lead to permanent visual impairment. However, prognostic factors and therapeutic strategy remain unclear.

METHODS

We retrospectively collected data from all patients diagnosed and managed for IIH in our university center from January 2001 to December 2016.

RESULTS

Seventy-nine patients were diagnosed with IIH. Bilateral transverse sinus stenosis (TSS) was found in 74% of the population. Visual outcome at 6 months was poor for 46% of patients, including all patients presenting weight gain of at least 5% since diagnosis (p < 0.001), whereas mean body mass index at diagnosis was not different between patients with poor versus good outcome (32.9 ± 7.7 versus 34.6 ± 9.4 kg·m^-2). Other significant factors of poor prognosis were bilateral TSS (OR = 5.2; 95 CI: 1.24-24.9; p = 0.024). Thirteen patients with poor outcome after 6-month assessment underwent unilateral TSS stenting leading to visual improvement in 11 cases.

CONCLUSION

Weight gain, rather than initial weight, emerged as the leading factor of poor visual outcome in patients with IIH, followed by presence of bilateral TSS. Consequently, first-line treatment must include dietary measures to control weight. Unilateral stenting appears to be a safe second-line treatment option for patients with bilateral TSS.

Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

Idiopathic intracranial hypertension has been associated with dural venous sinus stenosis in some patients, but the hemodynamic environment of the dural venous sinuses has not been quantitatively described. Here, we present the first such computational fluid dynamics model by using patient-specific blood pressure measurements.

MATERIALS AND METHODS

Six patients with idiopathic intracranial hypertension and at least 1 stenosis or atresia at the transverse/sigmoid sinus junction underwent MR venography followed by cerebral venography and manometry throughout the dural venous sinuses. Patient-specific computational fluid dynamics models were created by using MR venography anatomy, with venous pressure measurements as boundary conditions. Blood flow and wall shear stress were calculated for each patient.

RESULTS

Computational models of the dural venous sinuses were successfully reconstructed in all 6 patients with patient-specific boundary conditions. Three patients demonstrated a pathologic pressure gradient (≥8 mm Hg) across 4 dural venous sinus stenoses. Small sample size precludes statistical comparisons, but average overall flow throughout the dural venous sinuses of patients with pathologic pressure gradients was higher than in those without them (1041.00 ± 506.52 mL/min versus 358.00 ± 190.95 mL/min). Wall shear stress was also higher across stenoses in patients with pathologic pressure gradients (37.66 ± 48.39 Pa versus 7.02 ± 13.60 Pa).

CONCLUSIONS

The hemodynamic environment of the dural venous sinuses can be computationally modeled by using patient-specific anatomy and physiologic measurements in patients with idiopathic intracranial hypertension. There was substantially higher blood flow and wall shear stress in patients with pathologic pressure gradients.