Current-controlled deep brain stimulation reduces in vivo voltage fluctuations observed during voltage-controlled stimulation

Objective: Clinical deep brain stimulation (DBS) systems typically utilize voltage-controlled stimulation and thus the voltage distribution generated in the brain can be affected by electrode impedance fluctuations. The goal of this study was to experimentally evaluate the theoretical advantages of using current-controlled pulse generators for DBS applications. Methods: Time-dependent changes in the voltage distribution generated in the brain during voltage-controlled and current-controlled DBS were monitored with in vivo experimental recordings performed in non-human primates implanted with scaled-down clinical DBS electrodes. Results: In the days following DBS lead implantation, electrode impedance progressively increased. Application of continuous stimulation through the DBS electrode produced a decrease in the electrode impedance in a time dependent manner, with the largest changes occurring within the first hour of stimulation. Over that time period, voltage-controlled stimuli exhibited an increase in the voltage magnitudes generated in the tissue near the DBS electrode, while current-controlled DBS showed minimal changes. Conclusion: Large electrode impedance changes occur during DBS. During voltage-controlled stimulation, these impedance changes were significantly correlated with changes in the voltage distribution generated in the brain. However, these effects can be minimized with current-controlled stimulation. Significance: The use of current-controlled DBS may help minimize time-dependent changes in therapeutic efficacy that can complicate patient programming when using voltage-controlled DBS.