title: Proton MR Spectroscopy in Patients with Structural MRI-Negative Temporal Lobe Epilepsy.
abstract: OBJECTIVE
  With conventional magnetic resonance imaging (MRI), 20-30% of patients with temporal lobe epilepsy (TLE) have negative pathological MRI findings. Further investigations of the role of magnetic resonance spectroscopy (MRS) in the pre-surgical evaluation of patients with MRI-negative TLE are important to avoid intracranial EEG recording and to better understand the mechanism of the epileptogenic process. This study aimed to compare the measurements of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampi of MRI-negative TLE patients and normal subjects.
  
  
  METHODS
  Twenty patients with MRI-negative TLE and 10 age-matched healthy control subjects underwent MRI and MRS. The concentrations of NAA, Cr, and Cho and the ratios of NAA/Cr and NAA/(Cr+Cho) were measured. Seven of these 20 patients also underwent surgical treatment for TLE. Their pathological results and surgical outcomes were evaluated.
  
  
  RESULTS
  In the hippocampi ipsilateral to the seizure side, the NAA/Cr and NAA/(Cr+Cho) ratios were significantly decreased compared with the ratios of the hippocampi contralateral to the seizure side and the normal control hippocampi. There was no significant difference between the hippocampi contralateral to the seizure side and the normal control hippocampi. The pathological results from the patients who underwent temporal lobe resection indicated mild to moderate gliosis and minimal loss of neurons. Five patients were seizure-free during the follow-up period of 9- 47 months (mean 27.7 months).
  
  
  CONCLUSIONS
  In MRI-negative TLE, significant reductions in the NAA/Cr and NAA/(Cr+Cho) ratios ipsilateral to the seizure side may help lateralize and localize the epileptogenic zone.
authors.affiliation: Department of Neurology, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Xu
authors.affiliation: Department of Neurology, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Erhan
authors.initials: E
authors.lastname: Ergene
authors.affiliation: Department of Radiology, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Michael
authors.initials: M
authors.lastname: Zagardo
authors.affiliation: Department of Neurosurgery, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Tracy
authors.affiliation: Department of the Center for Outcomes Research, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Huaping
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Radiology, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: WenChing
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Neurology, Illinois Neurologic Institute, University of Illinois College of Medicine, Peoria, IL.
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Machens
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D013702:Temporal Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline
keywords: MR spectroscopy; MRI; temporal lobe epilepsy