Abstracts

There are some evidences based on neuropsychological and psychiatric evaluations as well as neuroimaging studies suggesting a frontal lobe dysfunction in patients with juvenile myoclonic epilepsy (JME). Savic et al (2000) demonstrated reduction in NAA levels in the prefrontal cortex of 15 patients with JME, not corroborated by others.
In this study, we aimed to evaluate the prefrontal cortex of patients with JME with a larger series of 38 patients using PRESS (Point Ressolved Spectrosocpy)., Thirty-seven patients with JME, median age of 21 years (12 to 49 years), followed in our Epilepsy Clinic, underwent a standard MR protocol. MR imaging examinations were performed on two 1.5-T scanners running the same software version (Signa Horizon LX; GE Medical Systems, Milwaukee, Wis). All the scans were interictal.
Single-voxel 1H MR spectroscopic acquisition of the right prefrontal cortex was prescribed by positioning a voxel (volume of interest) of 20 mm x 20 mm x 20 mm on an axial T2-weighted image. The MRS technique used was PRESS with a TE/TR of 35/1500 ms. Sixteen unsuppressed water reference acquisitions, followed by 96 water-suppressed acquisitions, were acquired for each voxel, while transmitter and receiver gains were kept constant. Spectral analysis was performed offline with public-domain MR user interface (MRUI) using the AMARES algorithm to fit the time-domain data to the following resonances: [italic]N[/italic]-acetylaspartate (NAA) at 2.02 ppm, creatine/phosphocreatine (Cr) at 3.02 ppm, choline-containing compounds (Cho) at 3.22 ppm, and myo-inositol (mI) at 3.56 ppm. The water signal was measured from the unsuppressed reference acquisitions by using the HLSVD algorithm. Metabolite/Cr and metabolite/water ratios were calculated and compared to normal values obtained for an age-matched control group. The two-tailed [italic]t [/italic]test was used for comparisons between different groups, and the Levene test was applied to determine whether or not variances were equal., There were no differences between patients and controls for any metabolite/Cr ratio. When comparing metabolite/water ratios the NAA/H20 and Cr/H20 were found to be slightly but significantly lower in the patients group (p=0.009 and p=0.03 respectively) compared to controls. The concomitant decrease of NAA and Cr explains the lack of differences found when the NAA/Cr was analyzed., Absolute levels of NAA were significantly decreased in patients with JME compared to controls. It corroborates the idea of functional changes of neuronal origin in the prefrontal cortex in patients with JME.
Savic I, Lekvall A, Greitz D, Helms G. MR spectroscopy shows reduced frontal lobe concentrations of N-acetyl aspartate in patients with juvenile myoclonic epilepsy.
Epilepsia. 2000 Mar;41(3):290-6.,