9, 10Īlthough functional neuroimaging such as PET or MRSI are valuable tools for localizing epileptic foci in TLE with normal MRI, 12 - 15 electrophysiological studies still have an important place in the detection of epileptic foci in the temporal lobe. 8 - 11 Compared with well-defined MTLE in which the atrophied hippocampus is nearly always the epileptic focus, TLE with normal MRI may be a heterogeneous condition either as a result of variable seizure onset or spread pattern. TLE may result from the lateral temporal cortex or mesial temporal structures, or the interaction between the lateral and mesial structures. Those patients have an older age of onset and less favorable surgical outcome compared with patients who have TLE with HS on MRI. Similarly, small or subtle cortical temporal pathologies may be undetected with current procedures. It is possible that some of these patients may have HS without HA (hippocampal atrophy) or T2-weighted signal changes that can be detectable using current technologies, and some may have bilateral HA that makes detection through volume asymmetry difficult. 1 - 5 It is estimated that at least 30% of patients with TLE have no evidence of HS on MRI. Diagnosis can be made by a combination of past history, clinical presentation, EEG and HS on MRI. Temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) on MRI is a well-known condition of surgically remediable mesial TLE syndrome (MTLE).

Normal eeg vs epileptic eeg