Abstracts

Rationale: The International League Against Epilepsy (ILAE) defines pharmacoresistant epilepsy as the failure of a patient s seizures to respond to at least two antiepileptic medications that are appropriately chosen and used for an adequate period (Kwan et al., 2010). There is an unmet need of clinical, electrophysiological and imaging biomarkers of pharmacoresistance. We aimed to analyze MRI findings in 60 consecutive patients with pharmacoresistant epileptic seizures in a single tertiary Epilepsy Center at the Institute of Neurology and Neuropsychology, Tbilisi, Georgia. Our goal was to delineate the spectrum of structural brain abnormalities in these 60 patients with pharmacoresistant epilepsy. Methods: We consecutively recruited and followed up for 24 months 60 patients with pharmacoresistant seizures from 2011-to 2013. All were clinically examined, underwent EEG and high-resolution MRI (3 T). The standard MRI protocol included T1-weighted 3D axial magnetization prepared rapid gradient echo (MPRAGE) images with and without intravenous contrast application, axial and coronal T2-weighted turbo spin echo, coronal T2-weighted fast fluid attenuated inversion recovery (FLAIR), T2*-weighted axial and diffusion weighted sequences. Coronal T2-weighted and FLAIR slices were 3 mm thick and were acquired at 90 perpendicular to the long axis of hippocampus. Seizure types and epilepsy syndromes were categorised according to the ILAE classification (1981, 1989). Based on ILAE recommendation, we defined seizures as pharmacoresistant if they persisted for at least 24 months despite the adequately administered at least two antiepileptic medications.Results: In total 60 patients were studied; 40 women and 20 men aged 4-55 (mean 25.6; median 25.5) years. The following structural brain abnormalities were observed in our patients cohort: hippocampal sclerosis (n=10), malformations of cortical development (n=7), tumour (n=3), post-traumatic lesions (n=3), hypothalamic hamartoma (n=2), other (n=19), no abnormalities (n=16). Lesions were located in the temporal lobe (n=11), mesial temporal structures (n=10), frontal lobe (n=8), parietal lobe (n=4), hypothalamus (n=2), corpus callosum (n=2), multifocal (n=17). Almost all patients (n=59) had supratentorial lesions, one patient had supra/infratentorial abnormality. The majority of patients had temporal lobe epilepsy (n=16), frontal lobe epilepsy was observed in 15 patients, parietal lobe epilepsy - in 6 patients, in two cases gelastic seizures were seen. Conclusions: In the majority of our cohort of patients with pharmacoresistant epilepsy no MRI abnormalities were observed (26%). The most common structural brain abnormalities were hippocampal sclerosis (17%) and malformations of cortical development (12%). The lesions were located mainly in temporal and frontal lobes.