Differences in ictal hyperperfusion of limbic-related structures between mesial temporal and neocortical epilepsy

Ictal propagation to the cortical and subcortical structures is well known in mesial temporal epilepsy (MTE) and neocortical epilepsy (NE). We analyzed the ictal changes of regional blood flow in limbic-related cortical and subcortical structures to evaluate the differences in ictal propagation patterns between MTE and NE.

In 65 patients (mean age, 29.1+/-10.83 years) with intractable MTE (n=46) or NE (n=19), ictal 99m-Tc ethyl cystinate dimer SPECT was performed. A subtracted ictal SPECT coregistered to MRI images was obtained in each patient. The patterns of subtracted ictal hyperperfusion in the limbic, paralimbic and subcortical structures in patients with MTE and NE were compared.

The ictal hyperperfusion of the amygdala, hippocampus, temporal pole and insula were significantly higher in MTE (P<0.01), but cingulate and orbitofrontal hyperperfusion were not. A significant difference in striatal ictal hyperperfusion between the MTE and NE group was found (P=0.035). Ictal hyperperfusion of NE was greater in the superior part (P=0.011), whereas that of MTE was greater in the inferior and middle parts.

These findings suggest that the ictal propagation of MTE may differ from that of NE via different pathways not only in the cortical regions but also in the subcortical structures.