Accurate Surgical Localization Using Combined Imaging Approach in Epilepsy

HOUSTON – Combined electroencephalography (EEG)/functional magnetic resonance imaging (fMRI) with electrical source imaging (ESI) is effective at identifying a single spatial target with high accuracy for use in epilepsy surgery. The study results were presented at the 2016 American Epilepsy Society Annual Meeting.¹

EEG/fMRI and ESI have previously demonstrated usefulness alone and combined in mapping regions of brain activity and localization of a spatial target needed in order to perform resective epilepsy surgery.^2-5 In this study, Maria Centeno, MD, of University College London, United Kingdom, and colleagues sought to assess and compare the localizing and predictive value of EEG/fMRI and ESI alone and combined in a cohort of pediatric patients with focal epilepsy.

Fifty-three pediatric patients with treatment-resistant epilepsy and frequent interictal epileptiform discharges (IEDs) were included in the study and underwent EEG/fMRI. Surgery was performed in 20 of those patients. Single localization was determined using a decision tree (available in the abstract). Once the epileptogenic focus was determined, accuracy measures predictive of surgery outcomes were compared between the combined method and EEG/fMRI or ESI alone.

Overall, 52 patients had significant results: 34 for combined EEG/fMRI and ESI; 13 for EEG/fMRI alone; and 5 for ESI alone. The combined method allowed for identification of a single localization in 47 of 53 patients, contributing to a more specific characterization of the epileptic focus in 64% of all patients and 82% of MRI-negative patients. Among the 19 patients who had significant results and underwent surgery, localization predicted surgery outcome with 100% sensitivity and 83% specificity. In comparison, EEG/fMRI alone and ESI alone demonstrated lower sensitivity and specificity (21%, 83% and 83%, 75%, respectively). Localization in 22 patients with concordant EEG/fMRI and ESI cluster predicted outcome with 100% sensitivity and specificity.

The authors concluded that the combined use of EEG/fMRI with ESI results in localization of the epileptic focus with a high degree of accuracy, noting that the approach is “particularly useful in providing a spatial hypothesis in MRI-negative cases.”

Disclosures: This study was supported by Action Medical Research.

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References

1. Centeno M, Perani S, Shamshiri E, et al. Better together? EEG-fMRI and ESI improve localization accuracy and predict surgical outcome in paediatric focal epilepsy. Presented at: 2016 American Epilepsy Society Annual Meeting; December 2-6, 2016; Houston, TX. Abstract 2.143.
2. Centeno M, Carmichael DW. Network connectivity in epilepsy: resting state fMRI and EEG-fMRI contributions. Front Neurol. 2014;5:93.
3. Brodbeck V, Spinelli L, Lascano AM, et al. Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients. Brain. 2011;134(Pt 10):2887-2897.
4. Russo A, Jayakar P, Lallas M, et al. The diagnostic utility of 3D electroencephalography source imaging in pediatric epilepsy surgery. Epilepsia. 2016;57(1):24-31.
5. Vulliemoz S, Lemieux L, Daunizeau J, Michel CM, Duncan JS. The combination of EEG source imaging and EEG-correlated functional MRI to map epileptic networks. Epilepsia. 2010;51(4):491-505.