Positron emission tomography in the study of epilepsy

Positron Emission Tomography with F-18-2-deoxy-glucose (FDG-PET) of offers functional, biochemical and molecular biological information which cannot be support by any other neuroimaging technic. Its main indication iii epilepsy is to localize the foci prior to a possible surgical treatment in patients with refractory partial seizure. In temporal lobe epilepsy, the most typical pattern is an unilateral hypometabolic area located in the temporal cortex, most frequently iii its mesial parts, although the lateral neocortex or the total lobe malt he affected This hypometabolic area includes the epileptogenic focus and the perifocal functional alterations. The possibility of delimiting the maximal extension of the foci allows ill some cases ro minimize partial resections with lower risk of side effects. The sensitivity shown to localize the foci is higher-than with RNM and similar to EEG monitoring with invasive deep electrodes. The high level of concordance observed bent een PET-FDG and invasive ictal EEG allows to avoid the use of invasive electrodes in cases with specific and doubtless PET findings. PET-FDG can ha helpful, too, studying seizures of extratemporal origin, mainly those with frontal or with multiple foci. In children with infantile spasm, the distribution of FDG shows abnormalities concording in 90% of cases with the epileptogenic region determined by monitoring with intracranial, electrodes. These patients may undergo successful surgical treatment with a 75-78% of patients becoming seizurefree. fil addition, PET allows to visualize the contralateral cortical function and p-edict the probable reorganization and functional recuperation after surgery. This is the reason for introducing PET-FDG in the evaluation of pediatric patients with intractable seizures as possible candidates to surgery [REV NEUROL 1997: 25 (Supl 4): S 418-23].