Idiopathic intracranial hypertension (IIH) is a serious pathologic elevation of intracranial pressure (ICP) that can lead to blindness, cognitive decline, debilitating headaches, and distressing pulsatile tinnitus (PT). IIH most commonly occurs in overweight women of childbearing age, and while it has an incidence of 20 in 100,000 in this patient cohort, the prevalence continues to increase with expansion of the obesity epidemic. Venous sinus stenting (VSS) is a promising emerging therapy for IIH in which operators implant a stent within the cerebral venous sinuses using endovascular technique. While VSS has favorable efficacy, relapse rates, and complication rates, there remains significant room for improvement. Relapse of IIH in VSS patients is typically due to development of edge-stenosis proximal to the VSS. The flow conditions responsible for edge-stenosis development are unknown. In addition, not all patients have durable resolution of their PT after VSS. PT is typically attributed to flow abnormalities in the veins that are also affected by IIH, but the specific cause of return of PT in IIH is also unknown. Evaluation of the hemodynamics within most intracranial stents is not possible through conventional imaging techniques due to their high-metal content. In this project we will conduct a systematic study that will first develop improved methods for MR measurement of pressure in the veins accounting for turbulent flow, developing flexible-walled patient-specific flow models that account for the unique environment of the cerebral venous sinuses, MR methods for measuring the velocity field in these models, as well as Computational Fluid Dynamics to interrogate features that cannot be easily manipulated in vivo or in the models. Advances in these techniques will allow for robust description of the hemodynamics, including pressure and turbulence, that is present in the pre-treatment and post-treatment patient. We will compare the obtained hemodynamic variables, geometric variables, and biologic variables to longitudinal evaluation of IIH patients treated with VSS to identify odds ratios of each variable on requirement of revision surgery and PT recurrence using regression analyses. This data will be used to develop a clinical tool prototype that is intended to assist physicians in determining the ideal stent size for each patient.
Idiopathic intracranial hypertension, a pathologic elevation of intracranial pressure, is a debilitating and dangerous disease that in many cases can be treated with venous sinus stenting. This emerging and promising therapy has significant risks of disease and symptom recurrence thought to be related to pressure fluctuations in the native vein and the stent, but the exact components of the hemodynamics are unknown. This project will systematically evaluate the hemodynamic variables, anatomical/geometrical variables, and stent variables using advanced imaging techniques on patient-specific flow models and computational models and compare these to longitudinal evaluations of recurrence in order to provide the necessary insights for the optimization of treatment strategies for these patients.
