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.
Bibliographical noteFunding Information:
The authors would like to thank Gary Russo, Weidong Xu, and Jianyu Zhang for their help with experimental preparations and Jennie Minnich for assistance in animal care. This research was supported by the National Institutes of Health (R01 NS047388, R01 NS037019, and F32 NS061541) and by a United States Department of Education Graduate Assistance in the Areas of National Need (GAANN) fellowship.
- Current-controlled stimulation
- Globus pallidus
- Non-human primate
- Subthalamic nucleus
- Voltage-controlled stimulation