Utility of Preoperative Simulation for Ventricular Catheter Placement via a Parieto-Occipital Approach in Normal-Pressure Hydrocephalus

BACKGROUND: Freehand ventricular catheter placement has been reported to have poor accuracy. OBJECTIVE: To investigate whether preoperative computational simulation using diagnostic images improves the accuracy of ventricular catheter placement. METHODS: This study included 113 consecutive patients with normal-pressure hydrocephalus (NPH), who underwent ventriculoperitoneal shunting via a parieto-occipital approach. The locations of the ventricular catheter placement in the last 48 patients with preoperative virtual simulation on the 3-dimensional workstation were compared with those in the initial 65 patients without simulation. Catheter locations were classified into 3 categories: optimal, suboptimal, and poor placements. Additionally, slip angles were measured between the ventricular catheter and optimal direction. RESULTS: All patients with preoperative simulations had optimally placed ventricular catheters; the mean slip angle for this group was 2.8 degrees. Among the 65 patients without simulations, 46 (70.8%) had optimal placement, whereas 10 (15.4%) and 9 (13.8%) had suboptimal and poor placements, respectively; the mean slip angle for the nonsimulation group was 8.6 degrees. The slip angles for all patients in the preoperative simulation group were within 7 degrees, whereas those for 31 (47.7%) and 10 (15.4%) patients in the nonsimulation group were within 7 degrees and over 14 degrees, respectively. All patients with preoperative simulations experienced improved symptoms and did not require shunt revision during the follow-up period, whereas 5 patients (7.7%) without preoperative simulations required shunt revisions for different reasons. CONCLUSION: Preoperative simulation facilitates accurate placement of ventricular catheters via a parieto-occipital approach. Minimally invasive and precise shunt catheter placement is particularly desirable for elderly patients with NPH.