Endovascular shunt feasibility in shunt responsive idiopathic intracranial hypertension: morphometric radiographic analysis

Background Patients with idiopathic intracranial hypertension (IIH) represent a unique population in whom mechanical shunting can be challenging. Endovascular cerebrospinal fluid shunting via the eShunt system has emerged as a potential alternative, but it is not currently approved for this indication, and its feasibility in IIH remains unknown. Methods In this retrospective, single center study, radiographic images of consecutively treated patients with shunt responsive IIH were assessed. Radiographic parameters involving the inferior petrosal sinus (IPS) and cerebellopontine angle (CPA) cistern were measured. We also examined whether the presence of a ventricular shunt at the time of imaging influenced radiographic candidacy, given the plausibility of cisternal changes after shunting. Results Of 53 patients (median age 41 years, 81.1% women), 24 (45.2%) were previously shunted before MRI imaging. The average CPA cisternal depth was 4.8±1.8mm (right) and 4.9±2.1mm (left); IPS size 3.5±0.7mm (right) and 3.4±0.8mm (left). The average off-axis angle trajectory from the IPS to the cistern was 128.6±9.8° (right) and 125.2±9.3° (left). In our final model, pre-existing ventricular shunt was not independently associated with endovascular shunting candidacy (OR 2.01, 95%CI 0.65 to 6.40; P=0.227). Overall, endovascular shunting was feasible in at least one side for 55% of patients, increasing to as high as 74% when assessment was based only on venous anatomy. Conclusion In this study, a sizeable proportion of patients with IIH were radiographic candidates for endovascular shunting, regardless of the presence of a pre-existing supratentorial shunt.