Correlation among anatomic landmarks, location of subthalamic deep brain stimulation electrodes, stimulation parameters, and side effects during programming monopolar review

BACKGROUND: Clinical benefits of deep brain stimulation can be limited by the presence of side effects produced by current spread to adjacent structures. OBJECTIVE: To identify a correlation between coordinates for each individual contact, neighboring structures, and pattern of side effects. METHODS: Coordinates of the electrodes and anatomic landmarks were obtained with a stereotactic surgical planning software and were correlated with stimulation-related side effects by using univariate and multivariable analyses. RESULTS: Monopolar stimulation elicited capsular side effects (CSE_s) in 208 of 316 contacts (65.8%) and noncapsular side effects (NCSE_s) in 223 of 316 contacts (70.6%). The occurrence of CSE_s was correlated with contact number (P = .009) and with the "Z" (P = .03), whereas voltage threshold to CSE_s exhibited correlation with the internal capsule angle (P = .035). The occurrence of NCSE_s was correlated with contact number (P = .005), "X" (P = .03), "Y" (P = .004), and the distance to the red nucleus (P = .001 and P = .003). There was correlation between voltage threshold to NCSEs and the internal capsule angle (P = .006), electrode's coronal angle (P = .02), "X" (P = .001), "Y" (P <.001), "Z" (P < .001), and the distances to the internal capsule (P = .02) and to the red nucleus (P = .004 and P < .001). CONCLUSION: A better understanding how patient anatomy, stimulation parameters, and lead location in relation to neighboring structures influence the occurrence of side effects can be useful to inform targeting strategies.