CORRELATION OF MRI HIPPOCAMPAL VOLUME ANALYSIS, VIDEO EEG MONITORING AND INTERICTAL AND POSTICTAL SINGLE-PHOTON EMISSION TOMOGRAPHY IN REFRACTORY FOCAL EPILEPSY

The effectiveness of surgery in patients with refractory complex parti al seizures depends on accurate localisation of the epileptogenic zone . To assess the correlation between magnetic resonance imaging (MRI) h ippocampal volume measurements, Tc 99m-hexamethylpropyleneamineoxime i nter- and postictal single photon emission computed tomography (SPECT) and clinico-electrophysiological (video/EEG) localisation of the epil eptogenic zone we prospectively studied 16 consecutive patients with r efractory complex partial seizures and no significant abnormality on s tandard MRI. Each test was interpreted blindly by independent observer s. Eight patients (50 %) had asymmetrical hippocampal volumes indicati ve of unilateral atrophy; correlation with the video/EEG and postical SPECT changes was very high (100 % with definitive video/EEG localisat ion, 75 % with interictal EEG and 83 % with postictal SPECT). Moreover , the left/right hippocampal ratio was able to differentiate temporal from extratemporal video/EEG localisations. Postictal SPECT showed reg ional lateralised changes in 9 (64 % ) of 14 technically satisfactory studies. Disagreement between the video/EEG and postictal SPECT was se en with two extratemporal and one bitemporal foci.