[Diagnosis of temporal lobe epilepsy by positron emission tomography]

Positron emission tomography (PET) was performed in 18 temporal lobe epileptics. About 20 mCi of 11C-glucose was perorally administered to the patients and 30 minutes later scanning was started when the transport of 11C-glucose from blood to the brain tissue reached equilibrium. At the level of 25 mm above orbitomeatal line, the slice image of the temporal lobe shows a relatively high metabolic oval ring involving the amygdala, hippocapal formation and the hippocampal gyrus medially and the T1, T2 and T3 neocortices laterally in normal subjects. The epileptic focus, when detected on PET images, was observed as a defect in this oval ring. In 15(83.3%) out of 18 cases, the location of epileptic focus was confirmed as a low metabolic defect. This diagnosis rate was higher than that of other focal epilepsy by PET study. The locations of foci were divided into three types: mesial (5 cases), lateral (4 cases) and combined (6 cases). The seizure symptoms of the patients were analyzed in terms of the correspondence to the focus types. The results showed that automatism and pseudoabsence had a close relation to the mesial and combined types and psychical, vertiginous or visual seizures correlated to the combined and lateral types. Visceral or motor seizures were induced equally by any focus types. These facts suggested that automatism and pseudoabsence were correlated with the mesial organs such as the amygdala and hippocampus and psychical, vertiginous or visual seizures had origin in lateral neocortices. Visceral or motor seizures were supposed to be the results of the spread from the temporal focus to the adjacent structures.(ABSTRACT TRUNCATED AT 250 WORDS)