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Source localization of ictal epileptic activity based on high-density scalp EEG data.
Epilepsia 2017; 58(6):1027-1036E

Abstract

OBJECTIVE

Electrical source imaging (ESI) is a well-established approach to localizing the epileptic focus in drug-resistant focal epilepsy. So far, ESI has been used primarily on interictal events. Emerging evidence suggests that ictal ESI is also feasible and potentially useful. We aimed to investigate the diagnostic accuracy of ESI on ictal events using high-density electroencephalography (EEG).

METHODS

We performed ictal ESI on 14 patients (9 with temporal lobe epilepsy) admitted for presurgical evaluation who presented seizures during a long-term (≥18 h) high-density EEG recording (13 with 256 electrodes and one with 128 electrodes), and subsequently 8 of them underwent epilepsy surgery (postoperative follow-up >1 year). Artifact-free EEG epochs at ictal οnset were selected for further analysis. The predominant ictal rhythm was identified and filtered (±1 Hz around the main frequency). ESI was computed for each time point using an individual head model and a distributed linear inverse solution, and the average across source localizations was localized. For validation, results were compared with the resection area and postoperative outcome.

RESULTS

Ictal ESI correctly localized the epileptic seizure-onset zone in the resection area in five of six postoperatively seizure-free patients. Interictal and ictal ESI were concordant in 9 of 14 patients and partially concordant in additional 4 of 14 patients (93%). Divergent solutions were found in only one of the 14 patients (7%).

SIGNIFICANCE

Ictal ESI is a promising localization technique in focal epilepsy.

Authors+Show Affiliations

Laboratory of Clinical Neurophysiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.Department of Fundamental Neurosciences, Functional Brain Mapping Lab, University of Geneva, Geneva, Switzerland.EEG & Epilepsy Unit, Department of Clinical Neurosciences, University Hospital of Geneva, Geneva, Switzerland.Department of Fundamental Neurosciences, Functional Brain Mapping Lab, University of Geneva, Geneva, Switzerland. Center for Biomedical Imaging (CIBM) Lausanne, Geneva, Switzerland.Department of Clinical Neurosciences, Neurosurgery Clinic, University Hospital of Geneva, Geneva, Switzerland.EEG & Epilepsy Unit, Department of Clinical Neurosciences, University Hospital of Geneva, Geneva, Switzerland.Laboratory of Clinical Neurophysiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.EEG & Epilepsy Unit, Department of Clinical Neurosciences, University Hospital of Geneva, Geneva, Switzerland.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

28398008

Citation

Nemtsas, Petros, et al. "Source Localization of Ictal Epileptic Activity Based On High-density Scalp EEG Data." Epilepsia, vol. 58, no. 6, 2017, pp. 1027-1036.
Nemtsas P, Birot G, Pittau F, et al. Source localization of ictal epileptic activity based on high-density scalp EEG data. Epilepsia. 2017;58(6):1027-1036.
Nemtsas, P., Birot, G., Pittau, F., Michel, C. M., Schaller, K., Vulliemoz, S., ... Seeck, M. (2017). Source localization of ictal epileptic activity based on high-density scalp EEG data. Epilepsia, 58(6), pp. 1027-1036. doi:10.1111/epi.13749.
Nemtsas P, et al. Source Localization of Ictal Epileptic Activity Based On High-density Scalp EEG Data. Epilepsia. 2017;58(6):1027-1036. PubMed PMID: 28398008.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Source localization of ictal epileptic activity based on high-density scalp EEG data. AU - Nemtsas,Petros, AU - Birot,Gwenael, AU - Pittau,Francesca, AU - Michel,Christoph M, AU - Schaller,Karl, AU - Vulliemoz,Serge, AU - Kimiskidis,Vasilios K, AU - Seeck,Margitta, Y1 - 2017/04/11/ PY - 2017/03/11/accepted PY - 2017/4/12/pubmed PY - 2017/7/14/medline PY - 2017/4/12/entrez KW - Drug-resistant epilepsy KW - Electrical source imaging KW - Epilepsy surgery KW - High-density interictal electroencephalography KW - Ictal electrical source imaging SP - 1027 EP - 1036 JF - Epilepsia JO - Epilepsia VL - 58 IS - 6 N2 - OBJECTIVE: Electrical source imaging (ESI) is a well-established approach to localizing the epileptic focus in drug-resistant focal epilepsy. So far, ESI has been used primarily on interictal events. Emerging evidence suggests that ictal ESI is also feasible and potentially useful. We aimed to investigate the diagnostic accuracy of ESI on ictal events using high-density electroencephalography (EEG). METHODS: We performed ictal ESI on 14 patients (9 with temporal lobe epilepsy) admitted for presurgical evaluation who presented seizures during a long-term (≥18 h) high-density EEG recording (13 with 256 electrodes and one with 128 electrodes), and subsequently 8 of them underwent epilepsy surgery (postoperative follow-up >1 year). Artifact-free EEG epochs at ictal οnset were selected for further analysis. The predominant ictal rhythm was identified and filtered (±1 Hz around the main frequency). ESI was computed for each time point using an individual head model and a distributed linear inverse solution, and the average across source localizations was localized. For validation, results were compared with the resection area and postoperative outcome. RESULTS: Ictal ESI correctly localized the epileptic seizure-onset zone in the resection area in five of six postoperatively seizure-free patients. Interictal and ictal ESI were concordant in 9 of 14 patients and partially concordant in additional 4 of 14 patients (93%). Divergent solutions were found in only one of the 14 patients (7%). SIGNIFICANCE: Ictal ESI is a promising localization technique in focal epilepsy. SN - 1528-1167 UR - https://www.unboundmedicine.com/medline/citation/28398008/Source_localization_of_ictal_epileptic_activity_based_on_high_density_scalp_EEG_data_ L2 - https://doi.org/10.1111/epi.13749 DB - PRIME DP - Unbound Medicine ER -