Abstracts

Rationale: Stereo-electroencephalography (SEEG), a longstanding tradition in France, Italy, and Canada, has earned global recognition among emerging surgery techniques in the past decade[1, 2]. International guidelines for SEEG terminology and interpretation are yet to be proposed. There are worldwide differences in SEEG definitions, application of features in epilepsy surgery planning, and interpretation of surgical outcomes. This hinders the clinical interpretation of SEEG findings and collaborative research. We aimed to assess the global perspectives on SEEG terminology, differences in the application of presurgical features, and variability in the interpretation of surgery outcome scores, and analyze how clinical expert demographics influenced these opinions.


Methods: We assessed the practices and opinions of epileptologists with specialized training in SEEG using a survey. Data was qualitatively analyzed, and subgroups were examined based on geographical regions, and years of experience. Primary outcomes included opinions on stereo-electroencephalography terminology, features used for epilepsy surgery, and interpretation of outcome scores. Additionally, we also conducted a multilevel regression and post-stratification analysis to characterize the non-responders.


Results: A total of 321 expert responses from 39 countries were analyzed (Fig. 1). We observed substantial differences in terminology, practices, and use of presurgical features across geographical regions and SEEG expertise. The majority of experts (217, 68.5%) favored the Lüders epileptogenic zone definition[3] than Bancaud’s definition[4]. Experts were divided regarding the seizure-onset-zone definition, with 195 (55.8%) favoring onset alone and 135 (42.1%) supporting onset and early propagation. In terms of presurgical SEEG features, a clear preference was found for ictal features over interictal features (Fig. 2A). Seizure-onset patterns were identified as the most important features by 265 experts (82.5%). Experts had varied opinions on the definition of low voltage fast activity (Fig. 2B) and also indicated a few additional quantitative measures used in the respective centers (Fig. 2C). We found similar trends after correcting for non-responders using regression analysis.


Conclusions: This study underscores the need for standardized terminology, interpretation, and outcome assessment in SEEG-informed epilepsy surgery. By highlighting the diverse perspectives and practices in SEEG, this research lays a solid foundation for developing globally accepted terminology and guidelines, advancing the field towards improved communication, and standardization in epilepsy surgery.

References: [1] Gavvala et al. J Clin Neurophysiol., 2022 [2] Abou-Al-Shaar et al. J Clin Neurophysiol., 2018 [3] Rosenow et al. Brain, 2001 [4] Talairach et al. Neurochirurgie, 1974.



Funding: CIHR (PJT-175056, MFE CIHR-IRSC:0633005463)