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Movement Disorders Parkinson’s Disease Deep Brain Stimulation for Parkinson’s Disease – A Review Christopher R Honey 1 and Manish Ranjan 2 1. Associate Professor of Neurosurgery, Surgical Centre for Movement Disorders, University of British Columbia, Vancouver; 2. Associate Professor of Neurosurgery, National Institute of Mental Health and Neuro Sciences, Bangalore Abstract The majority of patients with Parkinson’s disease (PD) can be treated with medications. As the disease progresses, however, certain symptoms may evolve that are refractory to medical therapy but ideally suited to surgical intervention. Tremor, dyskinesia and motor fluctuation can be effectively treated with deep brain stimulation (DBS). This article highlights which PD patients can benefit from DBS and summarises how the operations are performed and what are the expected outcomes (and potential complications). The relevant literature is reviewed for experienced clinicians and our personal bias is highlighted for those new to the field (and hoping to avoid our early mistakes). Keywords Parkinson’s disease, deep brain stimulation, tremor, dyskinesia, motor fluctuation, complication, outcome Disclosure: The authors have no conflicts of interest to declare. Acknowledgements: Christopher R Honey would like to acknowledge the patients of British Columbia with Parkinson’s disease, who have entrusted their lives to our team. We are honoured to have cared for them, humbled by their bravery and more knowledgeable for having treated them. Received: 2 February 2012 Accepted: 23 March 2012 Citation: European Neurological Review, 2012;7(1):28–34 Correspondence: Christopher R Honey, Surgical Centre for Movement Disorders, University of British Columbia, Suite 8105, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada. E: Any surgical procedure requires two things to be successful: selecting the correct patient and performing the operation correctly. The various operations of deep brain stimulation (DBS) for Parkinson’s disease (PD) are not particularly difficult. They comprise a series of steps that must be performed in an appropriate sequence and can be learned by most neurosurgeons within a year of fellowship training. The selection of the ideal patient, however, is much more difficult and is as much an art as a science. This article will summarise how DBS can be used to help patients with PD. The relevant literature will be presented for a comprehensive overview but we will focus on our personal experience (and bias) to provide practical guidelines. Each of the three main brain targets for this technique will be discussed and suggestions on patient selection, surgical technique, post-operative care and expected outcomes will be provided. The current popularity and wide acceptance of DBS for PD began in the early 1990s. Publications from the teams in Grenoble 1,2 and Lille 3 re-ignited interest in this technique after earlier publications had introduced the concept of DBS for PD but had not gained wide acceptance. 4 The concept that DBS could create a beneficial clinical effect without destroying tissue was very appealing. Prior to this technology, neurosurgeons could only destroy target areas in the brain. A variety of structures had been lesioned in an attempt to ameliorate PD, including the motor cortex, 5,6 the spinal cord motor pathways 7 and the basal ganglia. 8 The early experience (prior to 1960) was fraught with morbidity and mortality. 9 The more recent experience has been aided by accurate neuroimaging, intra-operative electrophysiological 28 confirmation of targeting and reproducible lesioning. During thalamotomy, macrostimulation of the ventral intermediate nucleus (Vim) with high-frequency stimulation (100 Hz) was known to block contralateral tremor whereas ‘low’-frequency stimulation (50 Hz) drove the tremor. 2 Permanent implantation of an electrode to chronically stimulate the Vim at high frequency was proposed to suppress tremor 2 and tested as a method to avoid the complications associated with bilateral thalamotomy. 1,10,11 Following a unilateral Vim thalamotomy, the contralateral side could be treated with DBS. Beneficial effects (i.e. blocking tremor) were obtained by increasing the voltage of stimulation and deleterious side effects (e.g. dysarthria) were avoided by reducing the voltage. The effect of DBS could be titrated. The ability to titrate the effect of DBS has remained its greatest asset. Adjusting the effect of DBS post-operatively to gain more benefit in a progressive disease or back away from a side effect is appealing to both the surgeon and patient. The concept that ‘we have not burned any bridges’ is also very appealing to many potential patients. Prospective patients often arrive for their surgical consultation emboldened by the concept that the surgeon is ‘only’ inserting an electrode in their brain and not burning any tissue. The review of potential risks of DBS is often surprising for the patients and is an essential part of their pre-operative assessment. With the success of Vim DBS in reducing tremor following contralateral thalamotomy, it was not long before DBS was used primarily to treat tremor without any prior thalamotomy. 2 DBS appeared to work like a reversible lesion and was therefore tried in the pallidum instead of pallidotomy. 12 At this time, surgeons began exploring the subthalamic nucleus (STN) as a target for PD and DBS © TOUCH BRIEFINGS 2012