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 efficacy 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.
Highlights
Deep brain stimulation (DBS), which involves the insertion of electrical leads into important cortical or subcortical structures to treat various neurological diseases, is often performed in a single surgery where the leads are subsequently connected to an implanted stimulator
These principles further support using a minimally biased trial period to evaluate for benefit, similar to techniques used in spinal cord stimulation (SCS) for chronic pain treatment
While sEEG is limited by the number of electrodes and sampled regions per patient when compared to more global brain network approaches such as ftuhnectiponoatlemntaiganletfioc rrefsooncaanlcestimulation imaging (fMRI) or MEG [40], it can better facilitate the characterization of biomarkers of clinical pain and stimulation with high spatiotemporal resolution
Summary
Deep brain stimulation (DBS), which involves the insertion of electrical leads into important cortical or subcortical structures to treat various neurological diseases, is often performed in a single surgery where the leads are subsequently connected to an implanted stimulator. Regardless, two large clinical trials evaluating combined VPL/PAG stimulation for chronic pain of various syndromes failed to meet therapeutic endpoints, though these studies were fraught with design and follow-up problems (see [14] for a discussion) These trials targeted the same two brain regions across hundreds of patients with vastly different pain syndromes without placebo or randomized design. A significant portion of patients were lost to follow-up; the resulting patient attrition severely reduced power to detect a clinically meaningful effect and resulted in no significant benefit using an intention-to-treat analysis These flaws highlight the need for individualized brain targeting based on etiology and the use of endpoints that measure multiple dimensions of pain. The hope is that through individual “N-of-1” DBS trial periods, we may find brain targets that produce acute pain relief that further extends to longer time periods
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