Evangelos Kogias1, Dirk-Matthias Altenmüller2, Kleanthis Karakolios3, Karl Egger4, Volker A Coenen5, Andreas Schulze-Bonhage2, Peter C Reinacher6. 1. Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany. 2. Epilepsy Center, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany. 3. Graduate School of Business, Columbia University, New York City, USA. 4. Department of Neuroradiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany. 5. Department of Stereotactic and Functional Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; Center for Deep Brain Stimulation, Medical Center - University of Freiburg, Freiburg, Germany. 6. Department of Stereotactic and Functional Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; Fraunhofer Institute for Laser Technology, Aachen, Germany. Electronic address: peter.reinacher@uniklinik-freiburg.de.
Abstract
BACKGROUND: Intracranial recordings with stereoelectroencephalography (SEEG) aims at defining the epileptogenic zone in patients with pharmacoresistant epilepsy. Currently used techniques for depth electrode implantation include stereotactic frame-based and navigated frameless applications, both either conventional or robot-assisted. Safety and diagnostic effectiveness depend on accuracy of implantation. OBJECTIVE: To evaluate the planning experience, accuracy of stereotactic electrode placement as well as accuracy predictors with the use of latest generation planning software. METHODS: Retrospective study of 15 consecutive patients who received depth electrodes using the Leksell stereotactic frame, after planning with Elements (Brainlab, Munich, Germany). For each electrode, we calculated the entry point error (EPE) as lateral deviation and target point error (TPE) both as lateral deviation and distance to tip. Multivariate regression analysis and computation of 95% confidence intervals using the bootstrap method were applied for statistical analysis and evaluation of accuracy predictors. RESULTS: The mean EPE, lateral deviation at TP and distance to tip at TP were 0.6 ±0.5 mm, 1.1 ±0.7 mm and 1.5 ±0.8 mm respectively. Order of implantation (1-6 vs. >6) is predictor for distance to tip at TP and length of electrode predictor for the lateral deviation at TP. Localization of electrode generally did not correlate to error, but insular electrodes were significantly less accurate than lobar ones. CONCLUSION: Combination of frame-based stereotaxy with latest generation planning software may offer a better planning and implantation experience. Accuracy predictors should be analyzed and be considered for the improvement of accuracy and safety of SEEG implantation methods.
BACKGROUND: Intracranial recordings with stereoelectroencephalography (SEEG) aims at defining the epileptogenic zone in patients with pharmacoresistant epilepsy. Currently used techniques for depth electrode implantation include stereotactic frame-based and navigated frameless applications, both either conventional or robot-assisted. Safety and diagnostic effectiveness depend on accuracy of implantation. OBJECTIVE: To evaluate the planning experience, accuracy of stereotactic electrode placement as well as accuracy predictors with the use of latest generation planning software. METHODS: Retrospective study of 15 consecutive patients who received depth electrodes using the Leksell stereotactic frame, after planning with Elements (Brainlab, Munich, Germany). For each electrode, we calculated the entry point error (EPE) as lateral deviation and target point error (TPE) both as lateral deviation and distance to tip. Multivariate regression analysis and computation of 95% confidence intervals using the bootstrap method were applied for statistical analysis and evaluation of accuracy predictors. RESULTS: The mean EPE, lateral deviation at TP and distance to tip at TP were 0.6 ±0.5 mm, 1.1 ±0.7 mm and 1.5 ±0.8 mm respectively. Order of implantation (1-6 vs. >6) is predictor for distance to tip at TP and length of electrode predictor for the lateral deviation at TP. Localization of electrode generally did not correlate to error, but insular electrodes were significantly less accurate than lobar ones. CONCLUSION: Combination of frame-based stereotaxy with latest generation planning software may offer a better planning and implantation experience. Accuracy predictors should be analyzed and be considered for the improvement of accuracy and safety of SEEG implantation methods.