The Localizaing Value of Ictal SPECT during Auras in Focal Epilepsy (P03.109)

Abstract

Objective: To evaluate the localizing value of Ictal Single Photon Emission Computed Tomography (SPECT) in isolated epileptic auras. Background Ictal SPECT is an important test to localize the epileptogenic zone (EZ) with an earlier injection reported as more successful. The epileptic aura is the earliest symptom of a seizure but there are little data on whether ictal SPECT injection during an isolated aura can localize the EZ. Design/Methods: From 529 ictal SPECT studies between 2003 and 2011 we identified 21 patients (5%) with focal epilepsy who had 27 ictal SPECT injections during isolated auras. Ictal and interictal SPECT studies were obtained using 99m TC-ECD as isotope, co-registered, normalized, subtracted, and transformed into a z-score and fused with the MRI (SISCOM). Studies were rated by 2 readers who blindly scored the SPECT for: presence or absence, lateralization, and localization of dominant hyperperfusion, and kappa statistics were calculated. Results are compared to aura type, time of injection, EEG findings during aura, and final localization or lateralization of the EZ based on consensus of scalp EEG, MRI, PET; invasive EEG, and post-operative outcome. Results: 8 patients had temporal, 4 frontal, 2 temporo-parietal, 1 fronto-temporal and 6 hemispheric epilepsy. The EZ was localized in 15 and lateralized in 6. Two readers agreed that 14/27 (52%) studies in 13/21 patients showed an area of dominant hyperperfusion with poor interobserver agreement (kappa=0.10). Of these 9/21 (43%) studies in 9/21 patients were correctly lateralized (kappa = 0.42 ) and only 1/15 studies in 1/15 patients were correctly localized (kappa=0.12). Studies obtained in auras with ictal EEG change were no more likely to be correctly localized (p=0.15). The timing of injection was not a predictor of success. Conclusions: Ictal SPECT injection during isolated auras has a low yield of correct localization of the EZ. Disclosure: Dr. So has nothing to disclose. Dr. Elwan has nothing to disclose. Dr. Alexopoulos has received personal compensation for activities with UCB Pharma as a speaker. Dr. Huang has nothing to disclose. Dr. Wu has nothing to disclose.