By implanting DBS leads in the deep brain structures, electrical stimulation can be provided and reduce symptoms like tremor completely or to a level which makes daily tasks possible. To provide an efficient therapy, the target position of the DBS lead is of high importance. Depending on symptoms, different targets are chosen but there is still a large variation in the clinical effect. We use different methods to understand this variation, probabilistic improvement maps and reconstruction of nerve tracts (tractography).
Probabilistic improvement maps can be created using a larger group of patients with varying clinical effect. The electric field can be simulated around the implanted leads using the finite element method (FEM). By combining electrical field strength, anatomical position, and clinical improvement, probabilistic maps can be created to highlight areas which are connected to better clinical improvement and areas associated to worse clinical improvement or side effects.
Tractography is a method that uses diffusion weighted magnetic resonance imaging (dMRI) to reconstruct nerve tracts. By combining FEM simulation with reconstruction of nerve tracts it is possible to evaluate the stimulation effect on a specific tract. If evidence between clinical effect and stimulation of a specific tract is found, tractography can be used clinically for target planning prior to surgery.