Rethinking the diagnostic criteria for cerebral venous outflow insufficiency: Is elevated intracranial pressure essential? A narrative review

Abstract: The relationship between intracranial hypertension (IH) and cerebral venous outflow insufficiency (CVOI), including cerebral venous sinus stenosis (CVSS) and internal jugular vein stenosis (IJVS), remains controversial. Although elevated intracranial pressure (ICP) is often regarded as a hallmark of CVOI, recent evidence indicates that a subset of patients with radiologically confirmed CVSS or IJVS exhibit normal or only mildly elevated ICP (< 250 mmH 2 O). This challenges the notion that ICP elevation is essential for diagnosis and raises concern about misdiagnosis when relying solely on ICP thresholds. This review summarizes the clinical features, imaging findings, and hemodynamic characteristics of CVOI and examines the bidirectional relationship between CVOI and ICP. Possible mechanisms for normal ICP include preserved lymphatic cerebrospinal fluid drainage, collateral venous pathways, and anatomical variation. Moreover, persistent ICP elevation may itself cause secondary venous collapse, creating a feedback loop. These findings suggest that ICP elevation is neither necessary nor sufficient for diagnosing CVOI. A multidimensional diagnostic framework, integrating symptomatology, venographic morphology, and venous flow dynamics, is essential to improve diagnostic accuracy and guide individualized management. Recognizing the complexity of this condition may prevent underdiagnosis and optimize outcomes for patients with CVOI.