Analyzing Spinal Cord Stimulation With Different Electrode Configurations: A Numerical Study

Spinal cord stimulation (SCS) represents a therapeutic approach for chronic pain management in patients refractory to conventional treatments. By implanting electrodes in the epidural space, SCS aims to mitigate pain transmission to the brain through electrical stimulation, often resulting in sensory perceptions such as paresthesia. This study investigates the influence of electrode configurations on electrical parameters, including current density and electric potential, within the spinal cord environment. Utilizing computational models of the spinal canal incorporating components such as epidural fat, cerebrospinal fluid (CSF), gray matter, and white matter, our analysis explores the distribution of electric potential and current density. Specifically, configurations employing four and nine electrodes are evaluated under both direct current (DC) and alternating current (AC) stimulations. For DC stimulations at currents of 1, 5, and 10 mA, our findings indicate that the four-electrode model generated current density values in epidural fat ranging from 107.90 to 130.98 mA/cm² and electric potential values ranging from 3.51 to 4.78 V. Similarly, the nine-electrode model produced current density values ranging from 92.51 to 223.61 mA/cm² and electric potential values ranging from 1.27 to 7.83 V under the same conditions. The results demonstrate a proportional relationship between applied current, current density, and electric potential. Furthermore, our investigation reveals a gradual decrease in electrical potential and current density from the epidural space to the gray matter. Discussions encompass the safety implications of these findings, examining whether the observed electrical parameters remain within tolerable limits for patient well-being. Additionally, the study explores the effects of AC stimulation across frequencies ranging from 250 Hz to 10 kHz, revealing an inverse correlation between frequency and charge parameters. Specifically, higher frequencies corresponded to reduced charge per phase and charge density, underscoring the frequency-dependent nature of these electrical properties.