This Article  • Full text  • PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Citing articles on ISI (35)  • Contact me when this article is cited  Related Content  • Related article  • Similar articles in this journal  Topic Collections  • EEG  • Neurology, Other  • Alert me on articles by topic  Social Bookmarking   What's this?

Not When the Interictal Electroencephalogram and Hippocampal Atrophy Coincide

Fernando Cendes, MD, PhD; Li M. Li, MD; Craig Watson, MD, PhD; Frederick Andermann, MD, FRCPC; François Dubeau, MD, FRCPC; Douglas L. Arnold, MD, FRCPC

Arch Neurol. 2000;57:497-500.

Objective  To investigate the concordance between scalp electroencephalogram (EEG) lateralization and side of hippocampal atrophy in patients with temporal lobe epilepsy (TLE).

Methods  We studied 184 consecutive patients with TLE without lesions other than those compatible with mesial temporal sclerosis. In this study, we studied specifically hippocampal atrophy and the results of scalp EEG investigation. Patients were classified according to the localization of interictal epileptiform discharges as unilateral, bilateral asymmetric, and bilateral symmetric. The EEG seizure onsets were also classified separately as unilateral, bilateral asymmetric, and bilateral symmetric. The hippocampal atrophy was determined by volumetric measurements using high-resolution magnetic resonance imaging (MRIVol).

Results  Only 3% of patients had discordance between the ictal and interictal EEG lateralizations; however, none of these had unilateral interictal EEG abnormalities. Interictal EEGs were considered unilateral in 62.0% of patients, bilateral asymmetric in 31.5%, and bilateral symmetric in 6.5%. Ictal EEGs were considered unilateral in 63.5% of patients, bilateral asymmetric in 30.0%, and bilateral symmetric in 6.5%. The MRIVol showed unilateral hippocampal atrophy in 60.9% of patients, bilateral asymmetric hippocampal atrophy in 19.0%, symmetric hippocampal atrophy in 3.8%, and normal volumes in 16.3%. There was a significant concordance between MRIVol lateralization and both interictal and ictal EEG lateralization (P<.001). All patients with unilateral hippocampal atrophy had concordant interictal and ictal EEG lateralization. Six (18.2%) of the 33 patients with bilateral asymmetric hippocampal atrophy had MRI lateralization discordant with EEG lateralization.

Conclusions  We found a strong concordance between EEG and MRIVol lateralization in patients with TLE. Unilateral hippocampal atrophy predicted ipsilateral interictal epileptiform abnormalities and ipsilateral seizure onsets with no false lateralization. Previous studies in addition to the present series support that a concordant outpatient EEG evaluation in patients with TLE and unilateral hippocampal atrophy would obviate the need for inpatient EEG monitoring.

From the Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec (Drs Cendes, Li, Andermann, Dubeau, and Arnold); and the Department of Neurology, Wayne State University School of Medicine, Detroit Medical Center, Detroit, Mich (Dr Watson). Dr Cendes is now with the Department of Neurology, University of Campinas, Campinas, Brazil.

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati     What's this?

RELATED ARTICLE

Archives of Neurology Reader's Choice: Continuing Medical Education
Arch Neurol. 2000;57(4):613-614.
FULL TEXT  

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Multimodal Coregistration in Patients with Temporal Lobe Epilepsy--Results of Different Imaging Modalities in Lateralization of the Affected Hemisphere in MR Imaging Positive and Negative Subgroups
Doelken et al.
Am. J. Neuroradiol. 2007;28:449-454.
ABSTRACT | FULL TEXT  

Apparent Diffusion Coefficient Mapping of the Hippocampus and the Amygdala in Pharmaco-Resistant Temporal Lobe Epilepsy
Pereira et al.
Am. J. Neuroradiol. 2006;27:671-683.
ABSTRACT | FULL TEXT  

Temporal lobe epilepsy surgery: different surgical strategies after a non-invasive diagnostic protocol
Quarato et al.
J. Neurol. Neurosurg. Psychiatry 2005;76:815-824.
ABSTRACT | FULL TEXT  

The development of hippocampal sclerosis in a patient with occipital lobe epilepsy and migraine
Simons et al.
Neurology 2004;62:1024-1025.
FULL TEXT  

The Requirement for Ictal EEG Recordings Prior to Temporal Lobe Epilepsy Surgery
Doherty et al.
Arch Neurol 2001;58:678-680.
FULL TEXT