title: Interictal epileptiform discharges relate to 1H-MRS-detected metabolic abnormalities in mesial temporal lobe epilepsy.
abstract: OBJECTIVE
  To examine whether the distribution of interictal epileptiform discharges (IEDs) recorded from foramen ovale electrodes (FOEs) correlates with metabolite levels in medial structures of the temporal lobes in patients with mesial temporal lobe epilepsy (MTLE).
  
  
  METHODS
  We studied 34 patients with MTLE. The lateralization ratio of IEDs was calculated after counting IEDs recorded from FOEs during prolonged video-EEG monitoring. Metabolite ratio between N-acetylaspartate (NAA) and creatine (Cr) was calculated in each medial temporal structure. The correlation between the lateralization ratio of IEDs and metabolic ratio was evaluated.
  
  
  RESULTS
  The asymmetry indexes of IEDs correlated with the asymmetry index of NAA/Cr ratio in the medial temporal structure (rho = -0.380; p = 0.027). Analysis of IEDs and metabolite ratio revealed a significant inverse relation in the contralateral side to the major epileptogenic focus (rho = -0.360; p = 0.037); however, this significance was not present in the ipsilateral side (rho = -0.018; p = 0.921).
  
  
  CONCLUSIONS
  There is a correlation between the neuronal dysfunction or damage detected by MRS and the epileptic activity in the contralateral medial temporal structure. Our results suggest that the pathomechanism underlying the contralateral reduction of NAA/Cr ratio, frequently observed in patients with MTLE, might be related to the process of epileptogenesis generating the independent contralateral IEDs.
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sun Ah
authors.initials: SA
authors.lastname: Park
authors.forename: Gyu Sik
authors.initials: GS
authors.lastname: Kim
authors.forename: Seung Koo
authors.initials: SK
authors.lastname: Lee
authors.forename: Sung Ryoung
authors.initials: SR
authors.lastname: Lim
authors.forename: Kyoung
authors.initials: K
authors.lastname: Heo
authors.forename: Soo Chul
authors.initials: SC
authors.lastname: Park
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Chang
authors.forename: Dong Ik
authors.initials: DI
authors.lastname: Kim
authors.forename: Byung In
authors.initials: BI
authors.lastname: Lee
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013702:Temporal Lobe / Q000378:metabolism
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine