Microelectrode accuracy in deep brain stimulation surgery.

Microelectrode recording (MER) provides vital neurophysiological information about target nuclei during deep brain stimulation (DBS). There have been extensive studies looking at the accuracy of DBS lead placement; however, to date, no large series have assessed the accuracy of the microelectrode. In this study, we report the accuracy of microelectrode tip placement in comparison to preoperatively planned radiographic target. Patients who underwent DBS with MER from 2014 to 2016 were included in the study. At the authors' institution, intra-operative CT (iCT) is routinely performed after the first microelectrode track to confirm tip accuracy. Retrospective analysis of microelectrode track error was calculated between the planned trajectory and the microelectrode tip. The radial error was calculated on the same axial plane using the Euclidian distance formula, and multivariate analysis was performed to ascertain any directional bias of error. A total of 227 microelectrode tracks were analyzed, (150 STN, 50 ViM, 27 GPi) yielding a total radial error of 1.2 mm ± 0.2 SEM across all targets. Analysis of vector error distribution revealed lack of directional bias. MER is an accurate electrophysiological representation of the planned target.