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Comparative Study
. 2011 May;52(5):941-8.
doi: 10.1111/j.1528-1167.2011.03061.x. Epub 2011 Apr 11.

The value of intraoperative electrocorticography in surgical decision making for temporal lobe epilepsy with normal MRI

Neal Luther  1 , Elayna Rubens, Nitin Sethi, Padmaja Kandula, Douglas R Labar, Cynthia Harden, Kenneth Perrine, Paul J Christos, J Bryan Iorgulescu, Guido Lancman, Neil S Schaul, Dmitriy V Kolesnik, Shahin Nouri, Andrew Dawson, Apostolos J Tsiouris, Theodore H Schwartz
Affiliations
Comparative Study

The value of intraoperative electrocorticography in surgical decision making for temporal lobe epilepsy with normal MRI

Neal Luther et al. Epilepsia. 2011 May.

Abstract

Purpose: We hypothesized that acute intraoperative electrocorticography (ECoG) might identify a subset of patients with magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE) who could proceed directly to standard anteromesial resection (SAMR), obviating the need for chronic electrode implantation to guide resection.

Methods: Patients with TLE and a normal MRI who underwent acute ECoG prior to chronic electrode recording of ictal onsets were evaluated. Intraoperative interictal spikes were classified as mesial (M), lateral (L), or mesial/lateral (ML). Results of the acute ECoG were correlated with the ictal-onset zone following chronic ECoG. Onsets were also classified as "M,""L," or "ML." Positron emission tomography (PET), scalp-EEG (electroencephalography), and Wada were evaluated as adjuncts.

Key findings: Sixteen patients fit criteria for inclusion. Outcomes were Engel class I in nine patients, Engel II in two, Engel III in four, and Engel IV in one. Mean postoperative follow-up was 45.2 months. Scalp EEG and PET correlated with ictal onsets in 69% and 64% of patients, respectively. Wada correlated with onsets in 47% of patients. Acute intraoperative ECoG correlated with seizure onsets on chronic ECoG in all 16 patients. All eight patients with "M" pattern ECoG underwent SAMR, and six (75%) experienced Engel class I outcomes. Three of eight patients with "L" or "ML" onsets (38%) had Engel class I outcomes.

Significance: Intraoperative ECoG may be useful in identifying a subset of patients with MRI-negative TLE who will benefit from SAMR without chronic implantation of electrodes. These patients have uniquely mesial interictal spikes and can go on to have improved postoperative seizure-free outcomes.

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Conflict of interest statement

Disclosure

None of the authors has any conflicts of interest to disclose. We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Figures

Figure 1
Figure 1
Lateral (A) and ventral (B) schematic diagrams of the brain showing electrode locations used for intraoperative ECoG as well as chronic monitoring. A depth electrode was additionally placed in the hippocampus for chronic monitoring. “M” denotes contacts used to determine mesial interictal spikes. Spikes at any other contact were considered lateral. Epilepsia © ILAE
Figure 2
Figure 2
Kaplan-Meier analysis of failure-free survival as defined as first postoperative seizure. Epilepsia © ILAE
Figure 3
Figure 3
Failure-free survival as defined as postoperative seizure in patients with “M” onsets (blue line) versus those with “L” or “ML” onsets (red line). Epilepsia © ILAE
See this image and copyright information in PMC

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