Instrumentation for neuromodulation.

The explosion in understanding how the central nervous system (CNS) works affords new opportunities to interact with the nervous system to compensate for dysfunction due to disease or injury. Neuromodulation is a term that describes methods that carry out that interaction based on principles of nerve cell physiology. There currently are two neuromodulation techniques used that require implantable devices-neurostimulation and implantable, chronic drug delivery. This article describes the devices used for neuromodulation, the motivation for the different feature sets of the devices, and the physiological and technological principles underpinning their use.