Subthalamic deep brain stimulation for advanced Parkinson’s disease Optimizing localization and stimulation of the target area

Deep brain stimulation (DBS) is an effective surgical treatment for advanced Parkinson’s Disease (PD). Continuous electrical stimulation within the subthalamic nucleus (STN), one of the basal ganglia, can successfully alleviate PD motor symptoms. However, the success of STN-DBS can be limited by side effects which can occur when unwanted neuronal areas or connections are stimulated. Therefore, it is important that the stimulation is targeted at the right location as specifically as possible. In this thesis we have studied several aspects of STN-DBS and how they contribute to optimal localization and stimulation of the preferred target area. We have used conventional imaging and electrode technology to study how the target area can be optimally located. Additionally, we have studied developments in imaging techniques and electrode design, i.e., the steering DBS electrode, to investigate how future technology can be used to further optimize both localization and stimulation of the most effective target area.
We conclude that a continuous effort should be made to critically review DBS targeting considering the evolving clinical and technological possibilities. We argue that targeting and steering stimulation are inseparable in optimizing DBS results. When targeting is inaccurate, steering stimulation might compensate for some of the lost potential benefit. However, the current preoperative planning with high field MRI and verification by intraoperative measurements and imaging make the targeting so accurate that it could perhaps be adapted specifically to the steering electrode. This thesis suggests that the full potential of steering electrodes could possibly be unleashed by targeting more specifically aimed at the dorsolateral motor segment of the STN.