A Proton Magnetic Resonance Spectroscopy Study of Metabolites in the Occipital Lobes in Epilepsy

Abstract

Summary:Purpose: ␥-Amino butyric acid (GABA) and glutamate, respectively the principal inhibitory and excitatory neurochemicals in the brain, are visible to proton magnetic resonance spectroscopy (MRS). We report a study of GABA+ (GABA plus homocarnosine) and GLX (glutamate plus glutamine) concentrations in the occipital lobes in patients with idiopathic generalised epilepsy (IGE) and in patients with occipital lobe epilepsy (OLE).Methods: Fifteen patients with IGE, 15 patients with OLE, and 15 healthy volunteers were studied. A single voxel was prescribed in the occipital lobes for each subject. PRESS localised short-echo-time MRS was performed to measure GLX by using LCModel. A double quantum GABA filter was used to measure GABA+. Segmented T 1 -weighted images gave the tissue composition of the prescribed voxel.Results: Grey-matter proportion, GLX, and GABA+ were all elevated in IGE. However, analysis using grey-matter proportion as a covariable showed no significant group differences. No correlation was observed between GABA+ concentration and either seizure frequency or time since last seizure.Conclusions: GLX and GABA+ were elevated in IGE. Elevated grey-matter content in the IGE group despite normal MRI appearance can be expected to account for some or all of this observed elevation of GLX and GABA+. GABA+ concentration did not correlate with seizure control or duration since most recent seizure.

Metabolic alteration transients during paroxysmal activity in an epileptic patient with fixation-off sensitivity: a case study

“…MRS-detected Glx elevation was found to be a feature of epileptic tissue, particularly after epileptic ictal activity [23][24][25][26], whereas we have found that, in the studied FOS subject, this increase is proportional to activation time during an 18-min task and is not just a static condition.…”

“…An increase in Glx in cortical lesions related to epilepsy has been reported after status epilepticus [23], while Woermann et al [24] found Glx alterations in hippocampi of TLE patients, both with and without hippocampal sclerosis. An increase of Glx was observed also in the occipital lobe of patients with idiopathic generalized epilepsy [25]. The increase of Glu in atrophic hippocampi was confirmed ex vivo [26].…”

The neurochemical profile quantified by in vivo 1H NMR spectroscopy

“…Higher magnetic fields, on the other hand, provide increased spectral resolution making GABA quantifiable (Deelchand et al, 2010;Gambarota et al, 2009;Mekle et al, 2009;Oz et al, 2006). GABA concentrations were found to be affected by neurological disorders like epilepsy (Doelken et al, 2010;Goddard et al, 2001;Simister et al, 2003), schizophrenia (Yoon et al, 2010), depression (Sanacora et al, 2004) or substance abuse (Behar et al, 1999;Ke et al, 2004).…”

Diagnostic methods for extra-temporal neocortical focal epilepsies: present and future

“…in extratemporal neocortical epilepsies, some aspects of brain metabolism of N-acetyl-aspartate, choline and creatine are essential [45][46][47] .…”