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.