Abstracts

Proton Magnetic Resonance Spectroscopy (1H-MRS) has been proposed as a lateralizing method for the presurgical evaluation of patients with medically intractable Temporal Lobe Epilepsy (TLE). Studies have shown correlations between temporal lobe (TL) NAA and seizure frequency, and TL NAA/Cr and the duration of epilepsy in patients with TLE. This latter finding may suggest that progressive neuronal dysfunction may occur in both temporal lobes in patients with TLE, even when the seizures originate in only one temporal lobe. We analyzed our data in an attempt to find a possible correlation between extension of neuronal dysfunction and duration of epilepsy.
We studied 45 consecutive patients with the diagnosis of TLE who were referred for presurgical evaluation at a large tertiary epilepsy center. Duration of epilepsy was defined as the interval between the age of seizure onset and the time of the MRS examination. All studies were performed in the interictal state, prior to intracranial monitoring or resection. We performed two-tailed Pearson correlation analysis between ipsilateral NAA/Cr and extension of the abnormality (voxels involved) and the duration of the seizure disorder in years.
The average duration of epilepsy in this group was 20 years. There was no significant correlation between duration of epilepsy and the ipsilateral NAA/Cr ratio (r = -.131, p = .390). A correlation between duration of epilepsy in years and extent of metabolic lesion (voxels involved) was not found either (r = -.264, p = .079).
We found no correlation between hippocampal NAA/Cr and the duration of epilepsy in TLE. Our findings raise the possibility that 1H-MRS measurements may not serve as markers for disease progression or epilepsy chronicity.
[Supported by: NIH]