Electric field focusing and shifting technique in deep brain stimulation using a dynamic tripolar current source

Deep brain stimulation (DBS) is a widely accepted clinical tool adopted for the treatment of a number of motor disorders. Despite its clinical efficacy, its underlying mechanisms have not been yet fully understood. One major issue that we identify as partly responsible for this lack of understanding is related to the poor control over the size, shape and location of the distribution of the depolarizing field around the electrode. With this and a parallel work the authors are proposing to develop and implement techniques that would allow for some degree of control over the distribution of the potential fields. This paper presents the application to DBS of a technique based on a tripolar current source configuration, with adjustable current flow through the lateral (anodic) branches of the tripole. The behavior of potential fields in the tissue were simulated by adopting FEM models of DBS electrode implanted in brain tissue. The profiles of simulated and measured fields were in agreement and they have shown how a dynamic tripolar current source can be adopted to obtain increase the focus and control the location of distribution of the fields around the electrode.