Electrode in the Brain: Some Engineering Aspects of Deep Brain Stimulation

Abstract

Deep brain stimulation (DBS) is an increasingly used surgical treatment for a range of neurological disorders, most commonly movement disorders. DBS provides durable electrical stimulation in different regions of the human brain according to a disorder specific manner. The mechanisms of action of DBS, particularly the interfaces between electrodes and brain are not well known and disputed. The interfaces have an impact on the outcome of the stimulation. This article presents an insight of electrochemical consideration at electrode-brain interface, the effects of electrode geometry, and the effect of current density distribution on the stimulation outcome. The understanding of the interface permits DBS to successfully treat a certain neurological disorder. The article also investigates the process and importance of charge balancing in neurons, and the hardware-related complications. Charge balancing technique enables DBS to yield a more predictable outcome and to be systematically developed as an effective treatment with minimum side effects. Moreover, the article synthesizes theoretical and empirical findings to provide a guidance for the selection of stimulus parameters. In this paper, experimental results, clinical studies, and human studies are reviewed. To spur on engineering and medical advances that will make DBS as a reliable and effective treatment for neurological disorders as cardiac pacemaker is now, the electrode-brain interfaces need to be continually re-assessed, the charge in brain might be balanced, and stimulation parameters need to be optimized. Keywords: Charge balancing, complications, deep brain stimulation, electrochemical, electrode.