John Libbey Eurotext

SISCOM and FDG-PET in patients with non-lesional extratemporal epilepsy: correlation with intracranial EEG, histology, and seizure outcome Volume 15, issue 1, March 2013

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Authors
Department of Pediatric Neurology, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Department of Neurology, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Institute of Nuclear Medicine, Charles University, 1st Faculty of Medicine, General University Hospital, Department of Nuclear Medicine and Endocrinology, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Department of Nuclear Medicine - PET Centre, Na Homolce Hospital, Department of Radiology, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Department of Pathology and Molecular Medicine, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Department of Neurosurgery, Charles University, 1st Faculty of Medicine, Military University Hospital, Department of Neurosurgery, Charles University, 2nd Faculty of Medicine, University Hospital Motol, Prague, Czech Republic

Aims. To assess the practical localising value of subtraction ictal single-photon emission computed tomography (SISCOM) coregistered with MRI and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with extratemporal epilepsy and normal MRI. Methods. We retrospectively studied a group of 14 patients who received surgery due to intractable epilepsy and who were shown to have focal cortical dysplasia, undetected by MRI, based on histological investigation. We coregistered preoperative SISCOM and PET images with postoperative MRI and visually determined whether the SISCOM focus, PET hypometabolic area, and cerebral cortex, exhibiting prominent abnormalities on intracranial EEG, were removed completely, incompletely, or not at all. These results and histopathological findings were compared with postoperative seizure outcome. Results. Two patients underwent one-stage multimodal image-guided surgery and the remaining 12 underwent long-term invasive EEG. SISCOM findings were localised for all but 1 patient. FDG-PET was normal in 3 subjects, 2 of whom had favourable postsurgical outcome (Engel class I and II). Complete resection of the SISCOM focus ( n=3), the area of PET hypometabolism ( n=2), or the cortical regions with intracranial EEG abnormalities ( n=7) were predictive of favourable postsurgical outcome. Favourable outcome was also encountered in: 4 of 8 patients with incomplete resection and 1 of 2 with no resection of the SISCOM focus; 4 of 7 patients with incomplete resection and 1 of 2 with no resection of the PET hypometabolic area; and 2 of 7 patients with incomplete resection of the area corresponding to intracranial EEG abnormality. No correlation between histopathological FCD subtype and seizure outcome was observed. Conclusion. Complete resection of the dysplastic cortex localised by SISCOM, FDG-PET or intracranial EEG is a reliable predictor of favourable postoperative seizure outcome in patients with non-lesional extratemporal epilepsy.