CT Guidance for Bolt-Kit External Ventricular Drains – Precision for the most Difficult Cases?

Aim: External ventricular drainage catheter (EVD) placement belongs to the most commonly performed neurosurgical procedures. The objective of the current study was to compare a CT-guided approach for placement of bolt-kit EVDs with conventional landmark-based insertion.

Methods: In this retrospective case-control study we analyzed patients undergoing placement of bolt-kit EVD catheters either CT guided or landmark-based between 2012 and 2016. In our CT-guided approach, an early CT scan after bolt fixation was performed and immediately reconstructed along the axis of the bolt to evaluate the putative insertion axis. In case of improper trajectory the angulation of the bolt was corrected and the procedure repeated. The primary endpoint was the accuracy of insertion. Secondary endpoints were the overall number of attempts, duration of intervention, complication rates and cumulative radiation dose.

Results: 34 patients were included in the final analysis. 15 patients underwent CT guided placement. In the group undergoing CT-guided placement average ventricle width was significantly smaller (p = 0.04) and average midline shift significantly more pronounced (p = 0.01). All patients undergoing CT guided placement showed a correct position of the catheter in the ipsilateral frontal horn. Landmark guided insertion resulted in a correct placement in 12 out of 19 (63%) patients (p = 0.01, Fisher's exact test). The overall number of CT scans performed during the insertion was 3.6 ± 1.9 in the CT-guided group compared with 1.84 ± 2.0 in the freehand group (p = 0.0001). No differences were found for the other secondary outcome parameters.

Conclusions: Our CT-guided approach for bolt-kit EVD catheter placement is feasible and results in higher accuracy of catheter placement even in difficult cases of slit ventricles or marked midline shift.