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MRI, (1)H-MRS, and functional MRI during and after prolonged nonconvulsive seizure activity
F Lazeyras1, O Blanke, I Zimine
1Department of Radiology, University Hospital of Geneva, Switzerland. francois.lazeyras@hcuge.ch
Background:
Various structural and functional changes, such as focal edema, blood flow, and metabolism, occur in the cerebral cortex after focal status epilepticus. These changes can be assessed noninvasively by means of MRI techniques, such as fluid-attenuated inversion recovery (FLAIR), EEG-triggered functional MRI (EEG-fMRI), and proton MR spectroscopy (MRS).
Methods:
The authors report on a 40-year-old patient with nonlesional partial epilepsy 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.
Results:
FLAIR imaging taken at the time of status epilepticus showed a signal hyperintensity in the occipital region. (1)H-MRS of this cortical region showed elevated lactate, decreased N:-acetylaspartate (NAA), and elevated choline (Cho). In the same region, EEG-fMRI revealed an area of signal enhancement. 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 sensitive sequences during clinically critical periods may disclose the structural correlate in a previously nonlesional epilepsy case. Corresponding to the clinical evolution, reversible and irreversible focally abnormal metabolism can be determined with (1)H-MRS, reflecting both increased neuronal activity and neuronal damage.
Insights
Repetitive MRI techniques can identify structural changes in nonlesional epilepsy. These methods reveal reversible and irreversible metabolic changes in the brain, reflecting neuronal activity and damage.
Area of Science:
- Neuroimaging
- Epileptology
- Biochemistry
Background:
- Focal status epilepticus causes structural and functional brain changes, including edema, altered blood flow, and metabolism.
- Magnetic resonance imaging (MRI) techniques like FLAIR, EEG-fMRI, and proton MR spectroscopy (MRS) offer noninvasive assessment of these cerebral cortex changes.
Observation:
- A patient with nonlesional partial epilepsy underwent serial MRI scans over one year.
- FLAIR showed occipital hyperintensity during status epilepticus, which resolved within 3 months.
- Proton MRS revealed elevated lactate and choline, with decreased N-acetylaspartate, in the affected region.
Findings:
- EEG-fMRI demonstrated signal enhancement in the seizure focus.
- Post-seizure control, lactate and choline levels normalized, but N-acetylaspartate remained reduced.
- The study highlights distinct patterns of reversible and irreversible metabolic alterations.
Implications:
- Repetitive MRI can uncover the structural basis of previously nonlesional epilepsy.
- Proton MRS can differentiate between neuronal activity and damage based on metabolic changes.
- Sensitive MRI sequences during critical periods are valuable for understanding epilepsy evolution.