*Review* **A Deep Brain Stimulation Trial Period for Treating Chronic Pain**

**Prasad Shirvalkar 1,2,3,\*, Kristin K. Sellers 2, Ashlyn Schmitgen 2, Jordan Prosky 1, Isabella Joseph 2, Philip A. Starr 2 and Edward F. Chang 2**


Received: 1 September 2020; Accepted: 25 September 2020; Published: 29 September 2020

**Abstract:** Early studies of deep brain stimulation (DBS) for various neurological disorders involved a temporary trial period where implanted electrodes were externalized, in which the electrical contacts exiting the patient's brain are connected to external stimulation equipment, so that stimulation e fficacy could be determined before permanent implant. As the optimal brain target sites for various diseases (i.e., Parkinson's disease, essential tremor) became better established, such trial periods have fallen out of favor. However, deep brain stimulation trial periods are experiencing a modern resurgence for at least two reasons: (1) studies of newer indications such as depression or chronic pain aim to identify new targets and (2) a growing interest in adaptive DBS tools necessitates neurophysiological recordings, which are often done in the peri-surgical period. In this review, we consider the possible approaches, benefits, and risks of such inpatient trial periods with a specific focus on developing new DBS therapies for chronic pain.

**Keywords:** deep brain stimulation; chronic pain; lead externalization; trial period; stereoEEG
