Optimizing deep brain stimulation using electrophysiological markers and electrical field steering

Abstract

Deep brain stimulation (DBS) is an effective treatment for a wide variety of neurological disorders. The efficacy of the treatment strongly depends on the exact location of the DBS-lead within the brain and the programming of the stimulation. In this work, methods and markers are presented which may be applied to improve both, the positioning and the programming of DBS-leads. Special consideration was given to ensure that any identified potential marker was not only a general effect of the stimulation itself, but actually a marker of clinical benefit. One method for achieving this goal was to investigate whether a qualitative change in clinical improvement was reflected in a qualitative change regarding an electrophysiological marker candidate. A second method to identify markers specific for clinical improvement was to separate the available data into patients responding to the treatment and patients not responding to the treatment. Therefore, potential marker candidates had to be present in the responder data, but absent in the non-responder data. Generally, marker candidates were discarded when they were strongly confounded by other effects like movement. DBS programming was not only optimized by providing more reliably sources of information during the programming process, but also by evaluating the effect of steering the electrical field. To this end, the clinical utility of segment DBS-lead contacts was compared to ring DBS-lead contacts. Refining of the implantation procedure itself was explored when a novel method to implant the DBS-leads into patients with Parkinson’s disease was investigated. This method allowed for the inclusion of electrophysiological information to the implantation process without the need to a priori record electrophysiological information with either a micro- or macro-electrode.