To study the tradeoffs of current steering technologies using the multiple independent current control (MICC) and multi-stim set (MSS) paradigms by comparing the volume of tissue activation (VTA) and power drain of each paradigm.

Deep brain stimulation (DBS) leads with radially segmented electrodes allow for current fractionation between multiple electrodes. Some DBS systems utilize MICC paradigm, where currents are distributed to two or more electrodes independently. Other DBS systems with a single current source can use MSS, where multiple stimulation parameters can be interleaved between electrodes in a sequential order. The outcome of these paradigms can be studied with a computational approach, where the volume of tissue activated (VTA) using each paradigm could be calculated and analyzed.

A computational model was implemented in Sim4Life v4.0 with the multimodal image-based detailed anatomical (MIDA) model and the Infinity^TM DBS lead placed in the STN. A grid of axons with multiple compartments were distributed on various axonal planes perpendicular to the lead. Three mA of current (with a 90 µs pseudobiphasic waveform) was distributed between two electrodes with various current splits. The volume and shape of the VTAs using MICC, MSS, and their energy consumption were computed and compared.

MSS VTA shows a lag in directional steering. However, compared to true current steering, both MSS and MICC show inaccuracy. The MSS VTA volume and shape was smaller and more compact with less current spread than MICC VTA. Depending on the impedances of the electrodes and the input current, MSS could draw more or less power than MICC.

While both current fractionation technologies achieve current steering between electrodes, this study illustrates the tradeoffs between accuracy, precision and power using MICC and MSS methods, with implications for programming approaches. MICC excels at current steering directionality, MSS achieves more focused activation.