How accurately are subthalamic nucleus electrodes implanted relative to the ideal stimulation location for Parkinson’s disease?

Abstract

Introduction The efficacy of subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson’s disease (PD) depends on how closely electrodes are implanted relative to an individual’s ideal stimulation location. Yet, previous studies have assessed how closely electrodes are implanted relative to the planned location, after homogenizing data to a reference. Thus here, we measured how accurately electrodes are implanted relative to an ideal, dorsal STN stimulation location, assessed on each individual’s native imaging. This measure captures not only the technical error of stereotactic implantation but also constraints imposed by planning a suitable trajectory. Methods This cross-sectional study assessed 226 electrodes in 113 consecutive PD patients implanted with bilateral STN-DBS by experienced clinicians utilizing awake, microelectrode guided, surgery. The error (Euclidean distance) between the actual electrode trajectory versus a nominated ideal, dorsal STN stimulation location was determined in each hemisphere on native imaging and predictive factors sought. Results The median electrode location error was 1.62 mm (IQR = 1.23 mm). This error exceeded 3 mm in 28/226 electrodes (12.4%). Location error did not differ between hemispheres implanted first or second, suggesting brain shift was minimised. Location error did not differ between electrodes positioned with (48/226), or without, a preceding microelectrode trajectory shift (suggesting such shifts were beneficial). There was no relationship between location error and case order, arguing against a learning effect. Discussion/Conclusion The proximity of STN-DBS electrodes to a nominated ideal, dorsal STN, stimulation location is highly variable, even when implanted by experienced clinicians with brain shift minimized, and without evidence of a learning effect. Using this measure, we found that assessments on awake patients (microelectrode recordings and clinical examination) likely yielded beneficial intraoperative decisions to improve positioning. In many patients the error is likely to have reduced therapeutic efficacy. More accurate methods to implant STN-DBS electrodes relative to the ideal stimulation location are needed.

Anatomical targeting for electrode localization in subthalamic nucleus deep brain stimulation: A comparative study

“…A consent waiver was provided by the ethics committee for retrospective data collection where data obtained were deidentified at the point of collection. This dataset has been used previously to explore factors that may influence DBS electrode surgical placement errors 19 …”

“…This dataset has been used previously to explore factors that may influence DBS electrode surgical placement errors. 19 …”

“…This dataset has been used previously to explore factors that may influence DBS electrode surgical placement errors. 19 Surgical procedure MRI at 3 Tesla (fluid-attenuated inversion recovery [FLAIR] and T1 sequences) was acquired preoperatively in the axial plane (Table 1). For 13 cases, T1 images were not available.…”