This chapter reviews the elements of anatomy that are required in order to understand and control deep brain stimulation (DBS) outcomes and side effects in patients with dystonia. The essential features for optimal programming in dystonia are: optimal electrode selection and configuration, amplitude, pulse width, and rate. One of the challenges of the initial programming in patients with dystonia is the virtual absence of immediate clinical response to stimulation. One of the very first reports describing successful treatment of dystonia with globus pallidus internal (GPi) DBS described maximal symptomatic relief with stimulation at 50 Hz, though at a very high pulse width. Appropriate DBS lead location is absolutely necessary to achieve optimal results. Currently available neurostimulators provide features that may help the programmer in distinguishing device-related problems from other forms of therapeutic failure. Current spread ventrally to the optic tract causes phosphenes and occasionally nausea.

This chapter focuses on the second critical factor for success of deep brain stimulation (DBS), namely the placement of the DBS lead. DBS implantation is a team-based neurosurgical procedure, led by a neurosurgeon who should be trained in functional, stereotactic neurosurgery. Intraoperative microelectrode recording (MER) does not cause morbidity but improves bradykinesia before placement of the DBS lead. Once the DBS lead has been placed at the target depth, intraoperative macro-stimulation using the DBS lead is performed to test for optimal placement. The goal of intraoperative DBS test stimulation is to assess the efficacy of placement and the therapeutic window of stimulation. A map should be made of the position of the DBS lead in the nucleus of choice, as this helps the clinician who ultimately performs the programming of the DBS system. Poor placement can result from lack of use of intraoperative physiological mapping techniques.