Basic principles of deep brain stimulation

Abstract

All evidence-based understanding regarding the principles of neurostimulation including deep brain stimulation (DBS) is based upon basic biophysical, electrochemical, and neurophysiological concepts. Scientific evidence for these concepts, although relatively old, provide a solid technical foundation regarding how to perform. Undoubtedly, the most striking progress in neuromodulation using DBS can be attributed to the enormous progress in anatomical, functional, and network visualization provided by MRI techniques. Only 25 years ago, all DBS implants were performed using ventriculography, which visualized only two landmarks in the three-dimensional brain: the anterior commissure and posterior commissure. Via a short period of CT-based DBS targeting in the first half of the 1990s, state-of-the-art DBS targeting is now based upon ever better and more revealing MRI techniques. Once the lead has been implanted in the patient’s brain, the device must be programmed to identify the optimal stimulation parameters that provide the most clinical benefit, the least amount of side effects, and ideally, utilize the lowest energy. This process is made easier with knowledge of the patient’s brain anatomy, stimulation-induced side effects of nearby structures, the lead trajectory, and basic concepts of extracellular stimulation. In this chapter the basic biophysical, electrochemical, and neurophysiological concepts pertinent to extracellular stimulation are reviewed.