Avoiding Insularity: Insights in Insular Semiology From sEEG

Anterior Versus Posterior Insular Epilepsy: Correlations With Semiology Based on Stereoelectroencephalography Chisholm J, Krishnan B, Khoury J, Alexopoulos A, Bingaman W, Serletis D, Najm I, Bulacio JC. Ann Neurol. 2025 Nov;98(5):1111-1124. doi: 10.1002/ana.70015. Epub 2025 Aug 13. PMID: 40799141; PMCID: PMC12577678. Objective: To characterize insular seizure semiology and correlate with stereoelectroencephalography (SEEG) seizure onset in a well-defined cohort, in particular examining differences between anterior and posterior insular seizures. Methods: We documented all semiological signs and the timing of emergence for 45 patients with SEEG-confirmed insular epilepsy, along with the precise location of the seizure onset zone (SOZ) within the insula. Semiological signs and other noninvasive data were compared between those with anterior and posterior insula SOZ, with more detailed insular subregion description when appropriate. Co-occurrence patterns of insular semiological signs were also investigated. Results: A total of 87% reported auras, and the corresponding insular SOZ demonstrated an anterior-to-posterior gradient by aura type. The absence of aura was significantly associated with an anterior insula SOZ ( p = 0.01). Late grunting/moaning ( p = 0.07), symmetric mouth elementary motor ( p = 0.1), blinking ( p = 0.05), and chewing/repetitive swallowing ( p = 0.09) also suggested an anterior insula SOZ. Unilateral nonpainful somatosensory aura ( p = 0.07) and early arm/hand elementary motor ( p = 0.1) suggested a posterior insular SOZ. Interpretation: We report the characteristics and semiological features in a large cohort of primary insular epilepsy patients. The type of aura is crucial for identifying the SOZ, and the timing of semiological emergence contributes to the anatomo-electro-clinical localization of an insular SOZ. These findings can enhance the identification of insular epilepsy, making targeted curative treatment feasible.