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Mesial Temporal Lobe Epilepsy

Tatum, William O. IV

Journal of Clinical Neurophysiology: October 2012 - Volume 29 - Issue 5 - p 356–365
doi: 10.1097/WNP.0b013e31826b3ab7
Invited Review
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Summary: Temporal lobe epilepsy (TLE) is the most common form of adult localization-related epilepsy. Hippocampal onset accounts for at least 80% of all temporal lobe seizures. The electroencephalogram (EEG) of mesial TLE contains interictal features often associated with anterior temporal epileptiform discharges with a maximal voltage over the basal temporal electrodes. Localized ictal patterns on scalp EEGs characteristically reveal unilateral 5- to 9-Hz rhythmic ictal theta or alpha epileptiform activity maximal in the anterior temporal scalp electrodes. Invasive-scalp EEG comparisons have yielded direct information about mesial temporal sources and their corresponding electrical fields. Refinement of macroscopic spatial and the temporal resolution suggest that a more precise seizure localization may exist beyond 1- to 35-Hz frequencies observed in routine scalp recording. Defining the focal areas of ictogenesis within the medial temporal lobe demonstrates a rich connection to a broad network that goes beyond the medial structures and even the temporal lobe itself. Advanced electrophysiologic application in TLE may further our understanding of ictogenesis to perfect surgical treatment and to elucidate the neurophysiologic corollaries of epileptogensis itself.

Department of Neurology, Mayo Clinic, Jacksonville, Florida, U.S.A.

Address correspondence and reprint requests to William O. Tatum IV, DO, Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, Florida 32224, U.S.A.; e-mail: tatum.william@mayo.edu.

Dr. Tatum receives research funding from the Mayo Clinic.

Copyright © 2012 American Clinical Neurophysiology Society