Abstracts

Severeal studies reported that there are some differences of ictal EEG, clinical semiology, and lateralization of ictal SPECT between patients with unilateral vs. bilateral interictal spikes in mesial temporal lobe epilepsy (TLE). To investigate the relationship between interictal epileptiform discharges (IED) vs. patterns of ictal hyperperfusion, we performed ictal-interictal SPECT subtraction in 54 patients with mesial TLE. The patients were divided into three groups: 1. patients with no IEDs during a long-term EEG monitoring (NIED group), 2. patients with [ge] 90% of IEDs occurring in one side of temporal lobes (UIED groups), 3. patients with [le] 90% of IEDs occurring in one side of temporal lobes (BIED group). All patients showed ictal hyperperfusion in ipsilateral temporal lobe to the seizure origin. In NIED group (N=7), all patients showed ictal hyperperfusion in anterior and mesial regions of the ipsilateral temporal lobe, and four had ipsilateral insular hyperperfusion. In UIED group (N=27), 12 patients (44.4%) showed small and subtle hyperperfusion in contralateral mesial temporal area, 14 (51.9%) had insular hyperperfusion of epileptic side and 12 (44.4%) showed ipsilateral basal ganglia hyperperfusion. In BIED group (N=21), 18 patients (85.7%) showed bilateral temporal hyperperfusion with ipsilateral predominance and there were multiple hyperperfusion areas in ipsilateral and contralateral frontal lobes and basal ganglia. The patterns of ictal hyperperfusion suggests that seizures of NIED or UIED groups are more localized while seizures of BIED group are more likely to spread to basal ganglia and frontal lobes, and contralateral temporal lobe.