title: PET imaging in extratemporal epilepsy requires consideration of electroclinical findings.
abstract: The study aimed to assess the relevance of interictal temporal glucose hypometabolism in patients with extratemporal epilepsy (ETE) by analyzing its association with a seizure semiology suggestive for temporal seizure involvement and the presence of temporal interictal epileptiform discharges (IEDs).
  
  
  
  We retrospectively reviewed the database of our epilepsy monitoring unit for patients with ETE, in whom long-term EEG-video-monitoring and [(18)F] fluorodeoxyglucose positron emission tomography (FDG-PET) had been performed. The localization of IEDs and the glucose hypometabolism were compared.
  
  
  
  Almost half (46%) of the 63 ETE patients had IEDs localized in the temporal lobe. Most patients (87.5%; 7/8) with temporal IEDs and an ipsitemporal hypometabolism showed seizure semiology suggestive of temporal or limbic system involvement in contrast to only 31.0% (9/29, p=0.01) in patients without temporal IEDs nor temporal hypometabolism. Those patients also showed an ictal seizure pattern spread into the ipsitemporal lobe, compared with 75.9% (22/29, n.s.) in patients without temporal IEDs nor temporal hypometabolism. Both, extratemporal (ipsilateral in 82.1%; 23/28 patients) and temporal (ipsilateral in 78.6%; 11/14 patients) hypometabolism significantly (p<0.05) lateralized to the epileptogenic hemisphere.
  
  
  
  The common temporal glucose hypometabolism in ETE patients reflects a remote epileptic dysfunction arising from extratemporal epileptogenic zones. Thus, interpretation of interictal FDG-PET results requires consideration of EEG results and seizure semiology to avoid false localization particularly in non-lesional epilepsy.
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: elisabeth.hartl@med.uni-muenchen.de.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Hartl
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: jan.remi@med.uni-muenchen.de.
authors.forename: Jan
authors.initials: J
authors.lastname: Rémi
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: christian.vollmar@med.uni-muenchen.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmar
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: joanna.goc@med.uni-muenchen.de.
authors.forename: Joanna
authors.initials: J
authors.lastname: Goc
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: annamira.loesch@med.uni-muenchen.de.
authors.forename: Anna Mira
authors.initials: AM
authors.lastname: Loesch
authors.affiliation: Department of Nuclear Medicine, University of Munich, Munich, Germany. Electronic address: axel.rominger@med.uni-muenchen.de.
authors.forename: Axel
authors.initials: A
authors.lastname: Rominger
authors.affiliation: Epilepsy Center, Department of Neurology, University of Munich, Munich, Germany. Electronic address: noa@med.uni-muenchen.de.
authors.forename: Soheyl
authors.initials: S
authors.lastname: Noachtar
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D001931:Brain Mapping; D004569:Electroencephalography; D004827:Epilepsy / Q000000981:diagnostic imaging* / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014741:Video Recording
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose
keywords: Extratemporal epilepsy; FDG-PET; Temporal IEDs; Temporal hypometabolism; Temporal semiology