Angiographic Evaluation of the Distance from the Top of the Jugular Bulb to the Inferior Petrosal Sinus–internal Jugular Vein Junction: Simple Classification and Identification Method for the Orifice of the Non-Visualized Inferior Petrosal Sinus During Neuroendovascular Surgery

The inferior petrosal sinus (IPS) is the transvenous access route for neurointerventional surgery that is occasionally undetectable on digital subtraction angiography (DSA) because of blockage by a clot or collapse. This study was aimed at analyzing the distance from the jugular bulb (JB) to the IPS–internal jugular vein (IJV) junction and proposing a new anatomical classification system for the IPS–IJV junction to identify the non-visualized IPS orifice. DSA of 708 IPSs of 375 consecutive patients were retrospectively investigated to calculate the distance from the top of the JB to the IPS–IJV junction, and a simple classification system based on this distance was proposed. The median distance from the top of the JB to the IPS–IJV junction was 20.8 ± 14.7 mm. Based on the lower (10.9 mm) and upper (31.1 mm) quartiles, IPS–IJV junction variants were: type I, 0–10 mm (22.3