Metabolic and electrophysiological alterations in subtypes of temporal lobe epilepsy: a combined proton magnetic resonance spectroscopic imaging and depth electrodes study

Epilepsia. 2002 Oct;43(10):1197-209. doi: 10.1046/j.1528-1157.2002.05102.x.


Purpose: This study compared the metabolic regional alterations, characterized by proton magnetic spectroscopic imaging ((1)H-MRSI), with electrophysiological abnormalities recorded by using depth electrodes and with structural lesions, in patients with several subtypes of temporal lobe epilepsy (TLE).

Methods: Twenty-five subjects were investigated, including 15 controls and 10 patients with drug-resistant unilateral TLE, nine of whom had structural abnormalities identified by MRI. All patients underwent noninvasive presurgical evaluation and then stereoelectroencephalography (SEEG). We performed an original metabolic exploration combining two (1)H-MRS imaging acquisitions associated with two single-voxel acquisitions (temporal poles) to map the most informative regions of interest (ROIs) including mesial and neocortical localizations. The N-acetyl aspartate/(choline+creatine) ratio was chosen as a metabolic index. SEEG analysis allowed the classification of each ROI as electrically normal or abnormal (i.e., involved in ictal and/or interictal discharges). Groups were compared by using a nonparametric Mann-Whitney U test.

Results: N-Acetyl aspartate/(choline+creatine) was significantly lower in all regions involved in SEEG electrophysiological epileptic abnormalities than in controls (p < 0.05). In contrast, the regions without any electrophysiological abnormalities were not metabolically different from those in controls (p > 0.05) except in one ROI. No differences between the metabolic profiles of epileptogenic and irritative zones were found. The metabolic alterations included, but also extended beyond, the lesions. The presence of metabolic abnormalities in mesial structures was not specific for the mesial subtype and generally extended outside the mesial structures.

Conclusions: These results indicate that metabolic abnormalities are linked to ictal and interictal epileptiform activities rather than to structural alterations in TLE.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amygdala / metabolism
  • Amygdala / physiopathology
  • Aspartic Acid / analogs & derivatives*
  • Aspartic Acid / metabolism
  • Choline / metabolism
  • Electrodes, Implanted
  • Electroencephalography / methods
  • Electroencephalography / statistics & numerical data*
  • Epilepsy, Temporal Lobe / diagnosis*
  • Epilepsy, Temporal Lobe / metabolism
  • Epilepsy, Temporal Lobe / physiopathology
  • Female
  • Hippocampus / metabolism
  • Hippocampus / physiopathology
  • Humans
  • Limbic System / metabolism
  • Limbic System / physiopathology
  • Magnetic Resonance Imaging / methods
  • Magnetic Resonance Imaging / statistics & numerical data
  • Magnetic Resonance Spectroscopy / methods
  • Magnetic Resonance Spectroscopy / statistics & numerical data*
  • Male
  • Middle Aged
  • Neocortex / metabolism
  • Neocortex / physiopathology
  • Phosphocreatine / metabolism
  • Temporal Lobe / metabolism
  • Temporal Lobe / physiopathology
  • Ureohydrolases / metabolism
  • Videotape Recording


  • Phosphocreatine
  • Aspartic Acid
  • N-acetylaspartate
  • Ureohydrolases
  • creatinase
  • Choline