Incidence and clinical profile of extra-medial-temporal epilepsy with hippocampal atrophy

We tried to investigate the incidence and the clinical profile of intractab le epilepsy with hippocampal atrophy and ictal onset zones located in areas other than the hippocampus (extra-medial-temporal epilepsy; EMTE). We incl uded patients who had hippocampal atrophy confirmed by MRI but with extra-m edial-temporal ictal onset zones as verified by invasive intracranial elect rodes or video-EEG monitoring. The case histories, interictal EEG, ictal se miology, other MRI findings in addition to hippocampal atrophy, and results of ictal SPECT and PET scans were evaluated. Results were compared with th ose of surgically proven medial temporal lobe epilepsy with hippocampal atr ophy recruited during the same period. 8.5% of the intractable epilepsy pat ients with hippocampal atrophy had extra-medial temporal epileptogenic zone s. A history of encephalitis and hemiconvulsion-hemiparesis were significan tly common in the EMTE group. Most of the interictal EEGs of EMTE patients showed extratemporal irritative zones. MRI, ictal SPECT, and FDG-PET seemed to be helpful at localizing the true epileptogenic zones. The predominant EMTE seizure type was focal motor seizure with secondary generalization. So me portion of intractable epilepsy patients with hippocampal atrophy had ex tra-medial-temporal epileptogenic fool and careful analysis of semiology an d neuroimagings could yield clues to correct diagnosis.