Needle-Based Intervention for Sacral Nerve Stimulation Using Electromagnetic Tracking and Virtual Images

We developed needle-based navigation system for sacral nerve stimulation. Inserting stimulation electrode into the foramen of the sacrum by trocar needle is a very challenging surgical technique. Skin-to-target path and real-time instrument guidance were provided by the designed software interface based on the pre-operative 3D model from 1.25 mm-sliced CT data. Using an electromagnetic navigation system, instrumented 18g needles were inserted into the target position in a dummy. The registration error between the CT coordinate and the electromagnetic tracking coordinate was 0.87 mm in the dummy. Seven nonexperts operated for 10 attempts on each subject, and conventional operation method was also tested by the same non-experts for comparing the accuracy assessment. The mean distance between the needle tip position and the center of the target in a virtual environment was 2.9±1.3 mm (n=70) in the navigation system, and was 8.7±4.1 mm (n=70) in the conventional operation method. The developed navigation system allows the instrument insertion into the target position precisely.