Positron Emission Tomographic Studies in Focal Epilepsy

Eight patients with various forms of focal epilepsy were examined with positron emission tomography (PET) for the study of cerebral glucose metabolism. A 4-rings (7 slices) positron camera was used. Photosynthetically produced C-11 glucose was employed as a tracer for the analysis of the energy metabolic pattern. All patients underwent X-ray CT examinations. With a specially designed fixation device the head could be aligned in a reproducable position so that identical sections could be studied with PET and CT. Coordinates for stereotactic localization of targets for surgery or electrode implantation could be directly determined on the images obtained from both types of examinations. As a rule, interictal EEG abnormalities corresponded to areas of reduced glucose uptake. In a few cases there was a perfect spatial correspondence between focal EEG changes and the presence of a well localized zone of hypometabolism. Some observations suggest that interictal epileptogenic activity may be associated also with hypermetabolism. Data obtained with PET appear to be particularly useful for the guidance of surgical treatment of epilepsy.