Symptomatic cerebral venous outflow resistance responds to stenting even in the absence of intracranial hypertension on manometry: a multicentre study.

PURPOSE: The relative contribution of venous outflow obstruction and intracranial pressure (ICP) to symptomatology and treatment response in Idiopathic Intracranial Hypertension (IIH) remains uncertain. Venous sinus stenting (VSS) is indicated in patients with significant trans-stenotic pressure gradients (TPG) and concordant symptoms. A subset of these patients demonstrates conventionally normal superior sagittal sinus (SSS) pressures. As SSS pressure is often interpreted as a surrogate for ICP, it remains uncertain whether these patients derive benefit from VSS. METHODS: A multicentre VSS registry was retrospectively queried to identify IIH patients with normal SSS pressure (≤ 15 mmHg). These patients were matched 1:1 to patients with elevated SSS pressure (> 15 mmHg) based on pre-stent TPG. Primary outcomes were improvement in headache, tinnitus and papilledema. Multivariable regression assessed the association between SSS pressure and clinical outcomes, adjusting for residual differences in pre-stent TPG. RESULTS: Among 517 patients undergoing VSS, 33 (6.4%) were eligible for inclusion in the normal SSS pressure cohort (median 12.0 mmHg) and matched to 33 patients with elevated SSS pressures (median 20.0 mmHg). Despite matching, median pre-stent TPG remained lower in the normal SSS group (6.0 vs. 8.0 mmHg, p < 0.01). Rates of headache, papilledema and tinnitus improvement were comparable between groups (82.8% vs. 69.7%, 90.9% vs. 77.3%, and 78.3% vs. 84.6%, respectively). After adjustment for TPG, SSS pressure was not associated with clinical outcomes. CONCLUSION: VSS appears beneficial even in the absence of intracranial hypertension on manometry. These findings support the relevance of venous outflow resistance in guiding stenting decisions.