MRI, H-1-MRS, and functional MRI during and after prolonged nonconvulsive seizure activity

Background: Various structural and functional changes, such as focal edema, blood flow, and metabolism, occur in the cerebral cortex after focal statu s epilepticus. These changes can be assessed noninvasively by means of MRI techniques, such as fluid-attenuated inversion recovery (FLAIR), LEG-trigge red functional MRI (EEG-fMRI), and proton MR spectroscopy (MRS). Methods: T he authors report on a 40-year-old patient with nonlesional partial epileps y in the left posterior quadrant in whom these MRI techniques were applied in an active seizure focus and repeated during a follow-up of 1 year. Resul ts: FLAIR imaging taken at the time of status epilepticus showed a signal h yperintensity in the occipital region. H-1-MRS of this cortical region show ed elevated lactate, decreased N-acetylaspartate (NAA), and elevated cholin e (Cho), In the same region, EEG-fMRI revealed an area of signal enhancemen t. After seizure control, recovery of lactate and Cho was observed, whereas the NAA level remained reduced. The structural abnormality demonstrated on FLAIR disappeared within 3 months. Conclusions: Repetitive MRI with sensit ive sequences during clinically critical periods may disclose the structura l correlate in a previously nonlesional epilepsy case. Corresponding to the clinical evolution, reversible and irreversible focally abnormal metabolis m can be determined with 1H-MRS, reflecting both increased neuronal activit y and neuronal damage.