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Updated: Oct 25, 2026
Operative Technique and Nuances for the Stereoelectroencephalographic (SEEG) Methodology Utilizing a Robotic Stereotactic Guidance System
Published on: June 9, 2023
Impact of entry trajectory angle-to-skull on electrode placement accuracy in robot-assisted
Chan Park1, Jong Hyun Kim1, Ji Hyun Kim2
1Department of Neurosurgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Republic of Korea.
Objective:
Despite the widespread use of robotic systems to improve stereotactic accuracy in stereoelectroencephalography (SEEG), targeting errors still occur. Several studies have suggested that the trajectory-to-skull angle is closely associated with targeting error among various influencing factors; however, quantitative analyses remain limited. Therefore, this study aimed to quantitatively evaluate the relationship between trajectory-to-skull angle and implantation accuracy and to establish practical cut-off values for surgical planning.
Methods:
A total of 10 patients (103 electrodes) were included in this study and various clinical variables were analyzed to identify whether trajectory-to-skull angle has a significant relation with accuracy using multivariate linear regression. Then, receiver operating characteristic (ROC) curve analysis with Youden index optimization was applied to determine angle thresholds for achieving ≤ 3 mm accuracy.
Results:
Multivariate analysis showed that both axial and coronal trajectory-to-skull angles were significantly associated with target error, with more tangential incidence angles corresponding to larger deviations (p < 0.01). Axial angle-to-skull was particularly associated with anteroposterior (Y-axis) error, whereas coronal angle-to-skull primarily predicted superoinferior (Z-axis) error. ROC curve analysis identified optimal angle thresholds of 11.8° for axial trajectories and 6.3° for coronal trajectories to predict targeting accuracy within 3 mm. When both axial and coronal angles were maintained within these cut-offs, the probability of achieving a target error ≤ 3 mm was 88.2%.
Conclusion:
Trajectory-to-skull angle is a key geometric determinant of electrode placement accuracy in robot-assisted SEEG. Quantitative angle thresholds identified in this study provide practical guidance for trajectory planning and may help minimize mechanical deviation, improve implantation safety, and enhance the reliability of seizure-network localization.
