Glutamate metabolism in temporal lobe epilepsy as revealed by dynamic proton MRS following the infusion of [U¹³-C] glucose

Focal metabolic dysfunction commonly observed in temporal lobe epilepsy (TLE), and is associated with the development of medical intractability and neurocognitive deficits. It has not been established if this dysfunction is due to cell loss or biochemical dysfunction in metabolic pathways. To explore this question, dynamic ¹H MRS following an infusion of [U¹³- C] glucose was performed to measure glutamate (Glu) metabolism. Subjects (n = 6) showed reduced Glu levels (p < 0.01) in the ipsilateral mesial temporal lobe (MTL) compared with controls (n = 4). However, the rate of ¹³C incorporation into Glu did not differ between those with epilepsy and controls (p = 0.77). This suggests that reduced Glu concentrations in the region of the seizure focus are not due to disruptions in metabolic pathways, but may instead be due to neuronal loss or simplification.