Determinants of accuracy in frame-based stereoelectroencephalography: the role of experience, workflow, and selective use of guiding devices

Stereoelectroencephalography (sEEG) is an essential diagnostic procedure for patients with drug-resistant epilepsy. Accurate electrode placement is critical for reliable seizure localization and minimizing complications. The slotted guiding cannula has been proposed as an adjunct to improve implantation accuracy, though its clinical benefit remains uncertain.

This study evaluates the accuracy, safety, and complication profile of sEEG implantations performed with and without a slotted guiding cannula.

In this retrospective, single-center cohort study, 59 sEEG procedures were analyzed, encompassing 678 electrodes implanted using the Leksell G-frame system between September 2021 and May 2025. Postoperative CT imaging was fused with preoperative planning data to assess deviations at entry, target, and depth. Accuracy, complication rates, and workflow-related factors such as experience and implantation sequence were evaluated statistically.

Mean deviations were 0.35 ± 1.20 mm at entry, 1.46 ± 2.18 mm at target, and -1.76 ± 3.11 mm in depth. Potentially clinically relevant deviations (>2 mm entry/target or >10 mm depth) occurred in 6.6, 13.4, and 11.4% of electrodes, respectively. sEEG led to surgical therapy of various modalities in 27/53 patients (50.9%). Two patients required revision surgery due to significant deviations in electrode positioning (3.4% of surgeries) and one epidural hematoma needed surgical evacuation (1.7% of surgeries). Accuracy was strongly influenced by surgical workflow and surgeon experience, with a statistically significant improvement of depth accuracy (p = 0.0004). Progressive accuracy improvement over time indicated workflow refinement and procedural experience. The slotted cannula was not associated with a significant overall accuracy advantage.

Frame-based sEEG implantation demonstrates high accuracy and safety. Deviations were predominantly minor and clinically acceptable, Accuracy appears primarily determined by surgical experience and workflow standardization rather than adjunctive devices. Selective cannula use may be reasonable in technically demanding trajectories, but routine application does not confer measurable benefit.