Non-lesional mesial temporal lobe epilepsy

Prevalence of epilepsy was ۱% and ۳۰%-۴۰ % of them fall in to Drug resistant epilepsy. They are candidate for epilepsy surgery and success rate of resective epilepsy surgery was ۴۰-۹۰%.TLE is more frequent (۶۶%) focal epilepsy and ۳۰ % of them has normal MRI. Mesial TLE is a network disorder and more extensive structural abnormalities within and beyond temporal and extratemporal cortex and white matter both ipsilateral and contralateral to H.S was described. Clinicopathological, structural and functional difference was known between HS positive-TLE and Normal MRI-TLE. MRI negative TLE is not subtle version of HSTLE or mild HS it is a separate condition which affect distinct brain network.Negative MRI is highly dependent on imaging technique, magnetic field power and reviewers experience, so should be improved awareness.Determination of epileptogenic network has important role in presurgical evaluation. To reach this goal we can use invasive technique such as intracranial EEG or less/noninvasive technique such as quantitate MRI, DTI, MRS, FMRI, MSI, Volumetric study, PET scan/SPECT coregistered with MRI, EEG-FMRI, HD-ESI, ECoG. ۷۵-۸۰% of patient with normal MRI and Hypometabolism on FDG-PET ipsilateral to EEG onset seizure, has excellent post-surgical (ATL) outcome. New option is investigated for whom that not candidate for resective surgery (e.g. DBS, RNS, MRgLITT).