Fig 1.
Assessing the error between the actual versus ideal STN-DBS electrode location.
An example of the fused preoperative MRI and postoperative CT for a single patient with two electrodes implanted in the STN region. The nominated, ideal location to apply DBS in the dorsal STN is marked in red. The location of the electrode trajectory at this axial slice is defined by the electrode artefact occurring on CT (hyperintense voxels). The electrode location error is the straight-line (Euclidean) distance between the actual electrode trajectory versus the nominated, ideal location to apply DBS, as indicated by the blue arrows and measured in millimeters. A = Anterior, P = Posterior, L = Left, R = Right.
Fig 2.
The error in electrode placement between the nominated, ideal location to apply DBS in the dorsal STN versus actual electrode trajectory in 226 electrodes of 113 patients (A). An intraoperative microelectrode trajectory change was required in 48/226 (21.2%). There was no difference in electrode location error between electrodes preceded by one or more microelectrode trajectory changes versus those where no microelectrode trajectory change had occurred (Mann Whitney U-Test: U(47) = 3943, p = 0.21) (B). There was no difference in electrode location error between the first and second implanted side (Wilcoxon signed ranks: W(112) = 3106, p = 0.74) (C). There was no relationship between electrode location error and case number (linear regression: r = 0.09, p = 0.18, shaded region shows 95% confidence interval) (D).