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Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension.

ABSTRACT: 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.

SUBMITTER: Levitt MR

PROVIDER: S-EPMC5116292 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension.

Levitt M R MR McGah P M PM Moon K K Albuquerque F C FC McDougall C G CG Kalani M Y S MYS Kim L J LJ Aliseda A A

AJNR. American journal of neuroradiology 20160519 10

<h4>Background and purpose</h4>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.<h4>Materials and methods</h4>Six patients with idiopathic intracranial hypertension and at least 1 stenosis or atresia at the transverse/sig ...[more]

PMID: 27197986

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Project description:BackgroundOphthalmic outcomes following venous sinus stenting (VSS) in patients with idiopathic intracranial hypertension (IIH) are not well characterized.Materials and methodsA 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.ResultsEighty-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.ConclusionsOur 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.

Project description:BackgroundIdiopathic intracranial hypertension (IIH) is a syndrome of elevated intracranial pressure of unknown etiology. Unilateral or bilateral transverse sinus (TS) or transverse-sigmoid junction stenosis is present in about 30%-93% of these patients. There is an ongoing debate on whether venous sinus stenosis is the cause of IIH or a result of it. The subset of IIH patients who continue to have clinical deterioration despite maximum medical therapy is termed as "refractory IIH." Traditionally, cerebrospinal fluid diversion surgeries (ventriculoperitoneal shunt and lumboperitoneal shunt) and optic nerve sheath fenestration (ONSF) were the mainstays of treatment for refractory IIH. In the last decade, venous sinus stenting (VSS) has emerged as a safe and effective option for treating refractory IIH patients with venous sinus stenosis. Through this study, we want to share our experience with venous stenting in refractory IIH patients with venous sinus stenosis associated with a significant pressure gradient (≥10 mm Hg).MethodsRetrospective chart review of all the patients diagnosed with refractory IIH who underwent VSS or angioplasty at our comprehensive stroke center from November 2016 to March 2019.ResultsA total of seven refractory IIH patients underwent VSS or angioplasty within the specified period. The mean age was 39 years. Eighty-five percent of the patients were women (n = 6). The mean body mass index (BMI) was 37 kg/m2. Headache was the most common symptom (85%, n = 6) followed by transient visual obscurations (71%, n = 5) and pulsatile tinnitus (57%; n = 4). All patients had papilledema. Fifty-seven percent of patients (n = 4) had impaired visual field. Mean lumbar opening pressure was 40.6 cm H2O (SD = 9.66; 95% CI = 33.5-47.7). All patients were on maximum doses of acetazolamide ± furosemide. Six patients (85%) had dominant right transverse-sigmoid sinus. Fifty-seven percent of the patients had severe right transverse ± sigmoid sinus stenosis (n = 4) and the rest (43%) had bilateral TS stenosis (n = 3). Prestenting mean trans-stenosis pressure gradient was 18 mm Hg (SD = 6.16; 95% CI = 13.43-22.57). Six patients (85%) were treated with TS stenting and one (15%) with only angioplasty. Poststenting mean trans-stenosis pressure gradient was 4.8 mm Hg (SD = 6.6; 95% CI = -0.1-9.7). All patients were able to come off their medications with significant improvement in neurological and ophthalmological signs and symptoms. No procedure-related complications occurred.ConclusionTS stenting ± angioplasty is a safe and effective means of treating refractory IIH with venous sinus stenosis associated with a significant pressure gradient (≥10 mm Hg).

Project description:Background and purposeIn medically refractory idiopathic intracranial hypertension, optic nerve sheath fenestration or CSF shunting is considered the next line of management. Venous sinus stenosis has been increasingly recognized as a treatable cause of elevated intracranial pressure in a subset of patients. In this article, we present the results of the largest meta-analysis of optic nerve sheath fenestration, CSF shunting, and dural venous sinus stenting. This is the only article that compares these procedures, to our knowledge.Materials and methodsWe performed a PubMed search of all peer-reviewed articles from 1988 to 2014 for patients who underwent a procedure for medically refractory idiopathic intracranial hypertension.ResultsOptic nerve sheath fenestration analysis included 712 patients. Postprocedure, there was improvement of vision in 59%, headache in 44%, and papilledema in 80%; 14.8% of patients required a repeat procedure with major and minor complication rates of 1.5% and 16.4%, respectively. The CSF diversion procedure analysis included 435 patients. Postprocedure, there was improvement of vision in 54%, headache in 80%, and papilledema in 70%; 43% of patients required at least 1 additional surgery. The major and minor complication rates were 7.6% and 32.9%, respectively. The dural venous sinus stenting analysis included 136 patients. After intervention, there was improvement of vision in 78%, headache in 83%, and papilledema in 97% of patients. The major and minor complication rates were 2.9% and 4.4%, respectively. Fourteen additional procedures were performed with a repeat procedure rate of 10.3%. Three patients had contralateral stent placement, while 8 had ipsilateral stent placement within or adjacent to the original stent. Only 3 patients required conversion to CSF diversion or 2.2% of patients with stents.ConclusionsPatients with medically refractory idiopathic intracranial hypertension have traditionally undergone a CSF diversion procedure as the first intervention. This paradigm may need to be re-examined, given the high technical and clinical success and low complication rates with dural venous sinus stenting.

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Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension.

Publications

Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension.

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