Emerging applications of deep brain stimulation.

Deep brain stimulation (DBS) implantation surgery is an established treatment modality for a variety of medical refractory movement disorders such as Parkinson's disease, essential tremors and dystonia. Following the success of DBS in these movement disorders with a high rate of safety and efficacy, there is a resurgence of interest in the utility of this modality in other medical refractory disorders. Consequently, neuromodulation has been explored for a variety of refractory conditions such as neuropsychiatric disorders (major depressive disorders, obsessive-compulsive disorders, addictions), eating disorders including obesity, traumatic brain injury, post-traumatic stress disorders (PTSD), dementias and chronic pain. This review provides an overview of the emerging applications of DBS in these disorders, including summary of the published literature. We have highlighted the pathophysiology and likely aberrant neural circuits involved in these refractory disorders. Current and possible surgical targets for neurosurgical intervention related to these disorders have also been discussed. Furthermore, recent advances such as closed loop systems; responsive neurostimulation systems and optogenetics techniques have been addressed.