Influence of encapsulation tissue reaction on the volume of tissue activated with deep-brain stimulation electrodes: A simulation study

The goal of this study was to determine the influence of tissue reaction on the volume of brain tissue that can be activated using implanted directional deep brain stimulation microelectrodes. A finite-element method model of an electrode structure and its interface with the surrounding neural tissue was developed. Electrical and geometrical parameters of the fibrous tissue encapsulation were varied in the model to determine their impact on the volume of activated brain tissue surrounding the microelectrodes. Results: both the electrical conductivity change (from short- to long-term implantation reference values) and the increase of encapsulation thickness were shown to have a significant influence on the reduction of the volume of the activated tissue. The thickness parameter was shown to be a dominant factor.