O-1-35. The verification for stimulation characteristics of Cortical Stimulator

Abstract

Objective Bipolar stimulation (BS) used in intraoperative mapping is said to have less influence of leakage current. Its characteristics were actually verified while comparing with monopolar stimulation (MS). Methods A stimulating probe was brought into contact with agar with a comb-shaped detection electrode (platinum) placed at intervals of 2 mm. The stimulation current was kept constant, and resistance and voltage between the electrodes were measured while changing the distance between the electrode and the stimulation probe. Results The calculated current decreased exponentially with the distance between the stimulation portion and the electrode. When the stimulation portion was 2 mm away from the detecting electrode in BS, the current became 1/3 or less of the set current and almost no detectable at 1 cm or more. The current by MS was same as that of BS at the stimulation-detection distance of 1 mm. The current by MS is less than 1/10 of the set current at 5 mm, which is higher than BS. In MS, slight current was observed even when the stimulation-detection distance was 2 cm or more away. Conclusion In MS, the spread of the current at the stimulation portion is larger than the BS. Clinically it was considered that current leakage was negligible for both stimulations.