Preoperative FDG-PET temporal lobe hypometabolism and verbal memory after temporal lobectomy

Objective: To examine the relationship of preoperative fluorodeoxyglucose ( FDG)-PET asymmetry in temporal lobe metabolism and memory outcome after ant erior temporal lobectomy (ATL). Methods: In a university-based epilepsy sur gery center, 60 ATL patients (27 left, 33 right) were divided into two grou ps: no/mild (n = 21) or moderate/ severe (n = 39) asymmetry in temporal lob e hypometabolism as determined by FDG-PET. All patients were nonretarded, a t least 18 years of age, left-hemisphere speech dominant, without MRI abnor malities other than hippocampal atrophy, and with unilateral temporal lobe origin of intractable complex partial seizures. Neuropsychological measures of intelligence and verbal and visual memory function were assessed preope ratively and 6 months postoperatively. Results: Left ATL patients with no/m ild asymmetry in FDG-PET temporal lobe metabolism exhibited significantly g reater verbal memory decline compared with left ATL patients with moderate/ severe hypometabolism. There was no significant relationship between PET as ymmetry and pre- to postsurgical IQ change. No significant relationship was observed between extent of PET hypometabolism and memory outcome for right ATL patients. Conclusions: FDG-PET asymmetry can be added to the preoperat ive clinical markers that appear useful in predicting verbal memory decline after left ATL.