The value of additional electrodes when stereo‐electroencephalography is inconclusive

• DOI: 10.1111/epi.17885
• Publication Date: 2024-01-24T15:45:11Z
• Authors: Adeel Ilyas; Laura Vilella; Carlos E. Restrepo; Jessica Johnson; Sandipan Pati; Nuria Lacuey; Samden Lhatoo; Stephen A. Thompson; Nitin Tandon
• Keywords: Stereoelectroencephalography

Abstract Objective Stereo‐electroencephalography (SEEG) is the preferred method for intracranial localization of seizure‐onset zone (SOZ) in drug‐resistant focal epilepsy. Occasionally SEEG evaluation fails to confirm pre‐implantation hypothesis. This leads a decision tree regarding whether addition electrodes (two‐step – 2sSEEG) or placement subdural (SDEs) after (SEEG2SDE) would help. There dearth literature encompassing this scenario, and here we aimed characterize outcomes following unplanned two‐step EEG (iEEG). Methods All 225 adult cases over 8 years at our institution were reviewed extract patient data evaluation. Three raters independently quantified benefits additional electrodes. The relationship between iEEG benefit clinical outcome was then analyzed. Results Fourteen patients underwent 2sSEEG nine SEEG2SDE. In former cohort, second procedure performed these reasons—precise SOZ (36%); defining margins eloquent cortex (21%); broadening coverage setting non‐localizable seizure onsets (43% cases). Sixty‐four percent consistently deemed beneficial (Light's κ = 0.80). first two indications much more than when not localizable (100% vs 17%, p .02). SEEG2SDE SDEs identified enabled delineation relative all cases. Significance useful if initial broadly concordant with original electroclinical hypothesis, where it can clarify onset zones delineate safe surgical margins; however, provides minimal implantation hypothesis erroneous, recommend that be generally utilized such SDE minimizes need helpful delineating boundaries ictal‐onset cortex.