MR spectroscopy shows reduced frontal lobe concentrations of N-acetyl aspartate in patients with juvenile myoclonic epilepsy

Purpose: Neuropsychological studies suggest frontal lobe dysfunctions in pa tients with juvenile myoclonic epilepsy (JME). In this study we investigate d whether an underlying mechanism could be a regional neuronal damage net v isible with structural magnetic resonance (MR), but detectable with magneti c resonance spectroscopy (MRS). Methods: The study included 15 patients with JME and 10 matched healthy con trols. Quantitative single voxel MRS was conducted at 1.5 Tesla by using a STEAM sequence (TR/TE/ TM = 6,000/30/13.7 ms). The voxels were placed over the right cerebellum, right thalamus, and the prefrontal and occipital cort ex. The quantitation included fitting of transmitter gain, and correction f or partial volume of cerebrovascular fluid. LC-Model was used for estimatio n of the absolute concentrations of total N-acetyl aspartate (NAA), choline s, total creatine, and myoinositol. Results: Patients with JME had significantly reduced prefrontal concentrati ons of NAA in relation to controls (9.1 +/- 1.0 vs. 10.2 +/- 0.8 mM; p = 0. 031 after Bonferroni correction. The other regions showed normal NAA values , as did the other metabolites. Conclusions: The observed reduction in NAA levels suggests a prefrontal neu ronal lesion in patients with JME.