The Predictive Value of FDG-PET for Lateralizing Wada Memory Dominance and Epileptic Focus in Patients with Temporal Lobe Epilepsy

ABSTRACT

Backgroud : To examine the predictability of regional cerebral glucose metabolism in determining Wada memory dominance and lateralizing epileptic focus. METHODS: 1 8 F-fluorodeoxyglucose positron emission tomography (FDG-PET) and Wada test were performed in 18 patients with temporal lobe epilepsy (TLE). Regions of interest were determined in mesial, polar, anterior-lateral, mid-lateral, and posterior-lateral regions of the temporal lobe. The asymmetry indices of FDG-PET (PET-AI) were calculated in each ROI of temporal lobe, and those of Wada memory test (Wada-AI) were obtained as well. RESULTS: Pearson correlation coefficient showed Wada-AI was significantly correlated with PET-AI in mesial (r=0.67, p=0.001), polar (r=0.55, p=0.010), anterior-lateral (0.55, p=0.009) and mid-lateral (r=0.51, p=0.016) temporal regions. However, after simple linear regression analysis, PET-AI of mesial temporal region alone was significantly correlated with Wada-AI (p=0.008). In localizing epileptic focus, Wada-AI could correctly lateralize the seizure focus in 90% of the left TLE and 75% of the right TLE patients. No false lateralization by Wada-AI was observed except two patients showing prolonged confusion after amobarbital injection who were not included in this study. The PET-AI of the mesial temporal region showed the highest sensitivity of seizure lateralization (100% of left TLE and 87.5% of right RLE). CONCLUSIONS: Although FDG-PET hypometabolism is observed both at mesial and lateral regions of the temporal lobe in mesial TLE, mesial temporal region appeared to be a dominant and leading area for lateralizing Wada memory dominance and epileptic focus.