Targeting of the subthalamic nucleus for deep brain stimulation: a survey among Parkinson's disease specialists

Abstract Background Deep brain stimulation (DBS) within or adjacent to the subthalamic nucleus (STN) currently represents the most common stereotactic procedure performed for Parkinson's disease. Better STN imaging is often regarded as a requirement for improving stereotactic targeting. But, remarkably enough, it is unclear whether there is a consensus about the optimal target. Objective and Methods To obtain an expert opinion on the site regarded optimal for 'STN stimulation', movement disorder specialists were asked to indicate their preferred position for an active contact on hardcopies of the Schaltenbrand and Wahren atlas depicting the STN in all three planes. This represented an idealized setting and it mimicked optimal imaging for direct target definition in a perfectly delineated STN. Results The suggested targets were heterogeneous, although some clustering was observed in the dorsolateral STN and subthalamic area. In particular, in the anterior-posterior direction the intended targets differed to a great extent. Most of the indicated targets are thought to also result in concomitant stimulation of structures adjacent to the STN, including the zona incerta, Fields of Forel, and/or the internal capsule. Conclusions This survey illustrates that most sites regarded as optimal for 'STN stimulation' are close to each other, but there appears to be no uniform perception of the optimal anatomical target, possibly influencing surgical results. The anatomical sweet zone for STN stimulation needs further specification since this information is likely to make MRI-based target definition less variable when applied to individual patients.