Differences between mesial and neocortical magnetic-resonance-imaging-negative temporal lobe epilepsy.
The aim of this study was to assess clinical and electrophysiological differences within a group of patients with magnetic-resonance-imaging-negative temporal lobe epilepsy (MRI-negative TLE) according to seizure onset zone (SOZ) localization in invasive EEG (IEEG).



According to SOZ localization in IEEG, 20 patients with MRI-negative TLE were divided into either having mesial SOZ-mesial MRI-negative TLE or neocortical SOZ-neocortical MRI-negative TLE. We evaluated for differences between these groups in demographic data, localization of interictal epileptiform discharges (IEDs), and the ictal onset pattern in semiinvasive EEG and in ictal semiology.



Thirteen of the 20 patients (65%) had mesial MRI-negative TLE and 7 of the 20 patients (35%) had neocortical MRI-negative TLE. The differences between mesial MRI-negative TLE and neocortical MRI-negative TLE were identified in the distribution of IEDs and in the ictal onset pattern in semiinvasive EEG. The patients with neocortical MRI-negative TLE tended to have more IEDs localized outside the anterotemporal region (p=0.031) and more seizures without clear lateralization of ictal activity (p=0.044). No other differences regarding demographic data, seizure semiology, surgical outcome, or histopathological findings were found.



According to the localization of the SOZ, MRI-negative TLE had two subgroups: mesial MRI-negative TLE and neocortical MRI-negative TLE. The groups could be partially distinguished by an analysis of their noninvasive data (distribution of IEDs and lateralization of ictal activity). This differentiation might have an impact on the surgical approach.
Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic. Electronic address: irena.dolezalova@fnusa.cz.
Irena
I
Doležalová
Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.
Milan
M
Brázdil
Brno Epilepsy Center, Department of Neurosurgery, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Jan
J
Chrastina
Brno Epilepsy Center, Department of Neurosurgery, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Jan
J
Hemza
First Department of Pathological Anatomy, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Markéta
M
Hermanová
Institute of Biostatistics and Analyses, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Eva
E
Janoušová
Department of Radiology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
Marta
M
Pažourková
Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.
Robert
R
Kuba
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001921:Brain / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019579:Neocortex / Q000000981:diagnostic imaging*; D019635:Neurosurgical Procedures; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012640:Seizures / Q000000981:diagnostic imaging / Q000503:physiopathology; D013702:Temporal Lobe / Q000000981:diagnostic imaging*; D016896:Treatment Outcome; D055815:Young Adult
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Clinical semiology; Invasive EEG; MRI-negative temporal lobe epilepsy; Mesial MRI-negative TLE; Neocortical MRI-negative TLE; Positron emission tomography; Semiinvasive EEG