PET manifestation in different types of pathology in epilepsy

To investigate the metabolic behavior of different disease processes and pathology in epilepsy, fluorodeoxyglucose-positron emission tomography (FDG-PET) images of 280 patients with refractory epilepsy who had been surgically treated were retrospectively analyzed. The image findings were compared with the surgical pathology report. For all the pathology types reported, the major manifestations were regional hypometabolism. Of patients with sclerosis 92.1% (153/166) demonstrated FDG hypometabolism; 5.4% (9/166) were normometabolic and 2.4% (4/166) had increased FDG uptake (hypermetabolism). Of patients with malformation of cortical development, 84.5% (60/71) demonstrated hypometabolism, 8.4% (6/71) hypermetabolism, and 7% (5/71) showed normal metabolism. All of the neoplasms (24/24) and inflammatory processes (25/25) showed regional hypometabolism. The study suggests that although the major findings on FDG-PET in patients with refractory epilepsy are hypometabolic, attention should also be paid to patients with regional hypermetabolism, which might sufficiently localize the seizure origin. It might be worthwhile to repeat the study if no regions of hypometabolism are found and the electroencephalography suggests frequent spiking activity.