Electrophysiologic mapping for deep brain stimulation for movement disorders.

Electrophysiologic mapping remains an integral component of deep brain stimulation (DBS) surgical procedures, particularly in movement disorder cases where functional maps are used to guide DBS lead placement in patients with Parkinson's disease, dystonia, or tremor. Overall, the goal of the surgical procedure is to implant the distal end of a chronic, multicontact depth electrode into a specific brain region for the purpose of delivering therapeutic electrical stimulation. Regions that are currently targeted for patients with movement disorders include the subthalamic nucleus, the ventral intermediate nucleus of the thalamus, and the globus pallidus. Multiple imaging modalities are used initially to derive a stereotactic plan and guide the initial microelectrode trajectory. Changes in neuronal firing rate and pattern, both spontaneous and in response to somatosensory stimulation, are used to establish the location of the tip of the microelectrode(s), while acute stimulation can be used to estimate the proximity of neighboring brain regions. In this chapter, we will provide an overview of the microelectrode recording process as it is commonly applied to refine image-based targeting of lead placement for DBS surgery.