Abstracts

The Role of Magnetoencephalography (MEG) and Subtraction Ictal-Interictal Single-Photon Emission Computed Tomography (SPECT) in the Evaluation of Children with Lesional and Non-Lesional Epilepsy

Abstract number : 2.045
Submission category : 3. Neurophysiology / 3D. MEG
Year : 2019
Submission ID : 2421494
Source : www.aesnet.org
Presentation date : 12/8/2019 4:04:48 PM
Published date : Nov 25, 2019, 12:14 PM

Authors :
Benjamin D. Edmonds, University of Pittsburgh Medical Center; Yoshimi Sogawa, University of Pittsburgh Medical Center; William Welch, University of Pittsburgh Medical Center; James Mountz, University of Pittsburgh Medical Center; Anto Bagic, University of

Rationale: The combination of prolonged video-EEG, MRI and PET are now standard for non-invasive surgical evaluation in most comprehensive epilepsy centers in the U.S. MEG and SPECT are used less frequently and in various combinations based on their availability with no clear guidelines for patient selection. The key issue with obtaining ictal SPECT is that it often leads to prolonged admissions in the attempt to capture an additional seizure after an initial seizure on EEG occurs. While in comparison, interictal MEG can be obtained as an outpatient. This study evaluates the concordance of subtraction ictal-interictal SPECT and interictal MEG to ictal scalp EEG to develop better algorithms of non-invasive surgical evaluation in children with both lesional and non-lesional epilepsy. Methods: We retrospectively reviewed all children (2-17yo) who underwent a pre-surgical evaluation with MEG and SPECT from 2013-2018 at Children’s Hospital of Pittsburgh. Patients were dichotomized to lesional and non-lesional epilepsy based on MRI report. This distinction was made due to differing hypotheses; in lesional cases, the primary hypothesis is to confirm ictal onset is lesion associated while in non-lesional cases there can be multiple hypotheses. Localization of seizure foci on MEG and SPECT were compared to ictal EEG obtained during pre-surgical evaluation. Concordance of each modality was evaluated according to the previously published scale (Neurology 2011;76:41-48). Lobar concordance = 2; hemispheric concordance = 1; no concordance = 0. Fisher’s exact test was used for statistical analysis. Results: A total of 28 patients (54% male, 61% lesional, median age at time of pre-surgical evaluation 13yo) were included for analysis. MEG had greater overall concordance with ictal scalp EEG at the lobar level compared to SPECT (MEG 57% vs. SPECT 39%, p=0.09), and this was especially so when only accounting for lesional cases (MEG 71% vs. SPECT 47%, p=0.04). In the comparison of lesional to non-lesional cases, both MEG and SPECT had greater lobar concordance in lesional cases (MEG: Lesional 71% vs. non-lesional 36%, p=0.1. SPECT: Lesional 47% vs. 27%, p=0.6). In 4 patients (2 non-lesional, 2 lesional) MEG had lobar level concordance where SPECT had no concordance or discordance. Conversely, there was 1 non-lesional patient for which SPECT was concordant to lobar level and MEG was discordant or had no concordance. Therefore, in 5 of 28 cases having both MEG and SPECT was essential to further surgical evaluation and supports them being complimentary modalities. Conclusions: This study suggests that MEG could be a valuable addition to the routine algorithm for pre-surgical epilepsy evaluation in children given its greater frequency of lobar concordance with ictal scalp EEG than SPECT and the relative ease with which it can be obtained in an outpatient setting. Funding: No funding
Neurophysiology