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Observational Study
. 2024 Feb 27;102(4):e208007.
doi: 10.1212/WNL.0000000000208007. Epub 2024 Jan 30.

Outcome of Epilepsy Surgery in MRI-Negative Patients Without Histopathologic Abnormalities in the Resected Tissue

Maurits W Sanders  1 Iskander Van der Wolf  1 Floor E Jansen  1 Eleonora Aronica  1 Christoph Helmstaedter  1 Attila Racz  1 Rainer Surges  1 Alexander Grote  1 Albert J Becker  1 Sylvain Rheims  1 Hélène Catenoix  1 John S Duncan  1 Jane De Tisi  1 Thomas S Jacques  1 J Helen Cross  1 Reetta Kalviainen  1 Tuomas Rauramaa  1 Francine Chassoux  1 Bertrand C Devaux  1 Giancarlo Di Gennaro  1 Vincenzo Esposito  1 Istvan Bodi  1 Mrinalini Honavar  1 Christian G Bien  1 Thomas Cloppenborg  1 Roland Coras  1 Hajo M Hamer  1 Petr Marusic  1 Adam Kalina  1 Tom Pieper  1 Manfred Kudernatsch  1 Till S Hartlieb  1 Tim J Von Oertzen  1 Martin Aichholzer  1 Georg Dorfmuller  1 Mathilde Chipaux  1 Soheyl Noachtar  1 Elisabeth Kaufmann  1 Andreas Schulze-Bonhage  1 Christian F Scheiwe  1 Cigdem Özkara  1 Thomas Grunwald  1 Kristina Koenig  1 Renzo Guerrini  1 Carmen Barba  1 Anna Maria Buccoliero  1 Flavio Giordano  1 Felix Rosenow  1 Katja Menzler  1 Rita Garbelli  1 Francesco Deleo  1 Pavel Krsek  1 Barbora Straka  1 Alexis A Arzimanoglou  1 Joseph Toulouse  1 Wim Van Paesschen  1 Tom Theys  1 José Pimentel  1 Isabel M Loução De Amorim  1 Nicola Specchio  1 Luca De Palma  1 Martha Feucht  1 Theresa Scholl  1 Karl Roessler  1 Rafael Toledano Delgado  1 Antonio Gil-Nagel  1 Savo Raicevic  1 Aleksandar J Ristic  1 Olaf Schijns  1 Jan Beckervordersandforth  1 Victoria San Antonio-Arce  1 Jordi Rumia  1 Ingmar Blumcke  1 Kees P Braun  1 as the European Epilepsy Brain Bank Consortium (EEBB)  1
Affiliations
Observational Study

Outcome of Epilepsy Surgery in MRI-Negative Patients Without Histopathologic Abnormalities in the Resected Tissue

Maurits W Sanders et al. Neurology. .

Abstract

Background and objective: Patients with presumed nonlesional focal epilepsy-based on either MRI or histopathologic findings-have a lower success rate of epilepsy surgery compared with lesional patients. In this study, we aimed to characterize a large group of patients with focal epilepsy who underwent epilepsy surgery despite a normal MRI and had no lesion on histopathology. Determinants of their postoperative seizure outcomes were further studied.

Methods: We designed an observational multicenter cohort study of MRI-negative and histopathology-negative patients who were derived from the European Epilepsy Brain Bank and underwent epilepsy surgery between 2000 and 2012 in 34 epilepsy surgery centers within Europe. We collected data on clinical characteristics, presurgical assessment, including genetic testing, surgery characteristics, postoperative outcome, and treatment regimen.

Results: Of the 217 included patients, 40% were seizure-free (Engel I) 2 years after surgery and one-third of patients remained seizure-free after 5 years. Temporal lobe surgery (adjusted odds ratio [AOR]: 2.62; 95% CI 1.19-5.76), shorter epilepsy duration (AOR for duration: 0.94; 95% CI 0.89-0.99), and completely normal histopathologic findings-versus nonspecific reactive gliosis-(AOR: 4.69; 95% CI 1.79-11.27) were significantly associated with favorable seizure outcome at 2 years after surgery. Of patients who underwent invasive monitoring, only 35% reached seizure freedom at 2 years. Patients with parietal lobe resections had lowest seizure freedom rates (12.5%). Among temporal lobe surgery patients, there was a trend toward favorable outcome if hippocampectomy was part of the resection strategy (OR: 2.94; 95% CI 0.98-8.80). Genetic testing was only sporadically performed.

Discussion: This study shows that seizure freedom can be reached in 40% of nonlesional patients with both normal MRI and histopathology findings. In particular, nonlesional temporal lobe epilepsy should be regarded as a relatively favorable group, with almost half of patients achieving seizure freedom at 2 years after surgery-even more if the hippocampus is resected-compared with only 1 in 5 nonlesional patients who underwent extratemporal surgery. Patients with an electroclinically identified focus, who are nonlesional, will be a promising group for advanced molecular-genetic analysis of brain tissue specimens to identify new brain somatic epilepsy genes or epilepsy-associated molecular pathways.

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Conflict of interest statement

The authors report no relevant disclosures. Go to Neurology.org/N for full disclosures.

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References

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