Anatomical situation of the subthalamic nucleus (STN) from midcommissural point (MCP) in Parkinson's disease patients underwent deep brain stimulation (DBS): an MRI targeting study

Introduction: It is demonstrated that the degree of clinical improvement in Parkinson's disease (PD) achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement. In addition, individual variability in the situation of subthalamic nucleus (STN) is responsible for spatial inter-individual fluctuations of the real patient's target. Objective: Our study was aimed to identify the anatomic location of STN from midcommissural point (MCP) in Iranian Parkinson's disease patients who underwent DBS by means of a 3-dimentional magnetic resonance imaging (MRI). Methods:Forty-six patients with the PD were recruied as candidates for bilateral implantation of STN-DBS (92 subthalamic nucleuses) were recruited. All these patients had bilateral implantation at the same operation. DBS and MRI parameters including the target coordinates (X, Y, Z) and the distances from MCP to the center of STN in all three axes on both sides were reported and calculated for each patient. Results:The location of STN was approximated by a site with 11 mm lateral, 3 mm inferior and 3 mm posterior to the midcommissural point. This distance was significantly lower in PD patients who aged >50 years in both right and left sides in the Y-axis direction. Conclusion: Our findings led to a considerable set of information which could help neurosurgeons during DBS procedure in Iranian PD patients. Despite the differences observed between various population of PD patients in the anatomical location of STN, our results further depicted the clustration of active contact points in same region.