Amygdala Enlargement in Patients with Mesial Temporal Lobe Epilepsy without Hippocampal Sclerosis

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Purpose: Patients with mesial temporal lobe epilepsy (MTLE) without MRI abnormalities (MTLE-NL) represent a challenge for definition of underlying pathology and for presurgical evaluation. In a recent study we observed significant amygdala enlargement (AE) in 14% of MTLE patients with MRI signs of hippocampal sclerosis. Areas of gray matter volume (GMV) increase could represent structural abnormalities related to the epileptogenic zone or part of a developmental abnormality. Our objective was to look for undetected areas of increased GMV in MTLE-NL using post processing MRI techniques to better understand the pathophysiology of this condition.

Methods: We evaluated 66 patients with MTLE-NL on visual analysis and 82 controls. Voxel-based morphometry (VBM) group analysis was performed with VBM8/SPM8 looking for areas of increased GMV. We then performed automatic amygdala volumetry using FreeSurfer software and T2 relaxometry to confirm VBM findings.

Results: Voxel-based morphometry group-analysis demonstrated increased amygdala volume in the MTLE-NL group compared to controls. Individual volumetric analysis confirmed AE in eight (12%) patients. Overall, from all patients with AE and defined epileptic focus, four (57%) had the predominant increased volume ipsilateral to the epileptic focus. These results were cross-validated by a secondary VBM analysis including subgroups of patients according to the volumetric data. T2 relaxometry demonstrated no amygdala hyperintense signal in any individual with significant AE. There were no clinical differences between patients with and without AE.

Discussion: This exploratory study demonstrates the occurrence of AE in 12% of patients with MTLE-NL. This finding supports the hypothesis that there might be a subgroup of patients with MTLE-NL in which the enlarged amygdala could be related to the epileptogenic process. Further studies are necessary but this finding could be of great importance in the understanding of MTLE-NL.

Related collections

Most cited references 20

Record: found
Abstract: found
Article: not found

The role of the limbic system in experiential phenomena of temporal lobe epilepsy.

Barry S. Horowitz, F. Andermann, P Gloor … (1982)

Experiential phenomena occurring in spontaneous seizures or evoked by brain stimulation were reported by 18 of 29 patients with medically intractable temporal lobe epilepsy who were investigated with chronic, stereotaxically implanted intracerebral electrodes. The phenomena mainly consisted of perceptual (visual or auditory) hallucinations or illusions, memory flashbacks, illusions of familiarity, forced thinking, or emotions. Experiential phenomena did not occur unless a seizure discharge or electrical stimulation involved limbic structures. For such phenomena to occur, seizure discharge or electrical stimulation did not have to implicate temporal neocortex. This was true even for perceptual experiential phenomena. Many experiential responses elicited by electrical stimulation, particularly when applied to the amygdala, were not associated with electrical afterdischarge. Limbic activation by seizure discharge or electrical stimulation may add an affective dimension to perceptual and mnemonic data processed by the temporal neocortex, which may be required for endowing them with experiential immediacy.

0 comments Cited 83 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI.

Noojan Kazemi, Caterina Giannini, Karolin F Meyer … (2009)

To determine the long-term efficacy of anterior temporal lobectomy for medically refractory temporal lobe epilepsy in patients with nonlesional magnetic resonance imaging (MRI). We identified a retrospective cohort of 44 patients with a nonlesional modern "seizure protocol" MRI who underwent anterior temporal lobectomy for treatment of medically refractory partial epilepsy. Postoperative seizure freedom was determined by Kaplan-Meyer survival analysis. Noninvasive preoperative diagnostic factors potentially associated with excellent surgical outcome were examined by univariate analysis in the 40 patients with follow-up of >1 year. Engel class I outcomes (free of disabling seizures) were observed in 60% (24 of 40) patients. Preoperative factors associated with Engel class I outcome were: (1) absence of contralateral or extratemporal interictal epileptiform discharges, (2) subtraction ictal single photon emission computed tomography (SPECT) Coregistered to MRI (SISCOM) abnormality localized to the resection site, and (3) subtle nonspecific MRI findings in the mesial temporal lobe concordant to the resection. In carefully selected patients with temporal lobe epilepsy and a nonlesional MRI, anterior temporal lobectomy can often render patients free of disabling seizures. This favorable rate of surgical success is likely due to the detection of concordant abnormalities that indicate unilateral temporal lobe epilepsy in patients with nonlesional MRI.

0 comments Cited 38 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

The pathology of magnetic-resonance-imaging-negative epilepsy.

Andreas V. Alexopoulos, Zhuyuan Wang, Imad Najm … (2013)

Patients with magnetic-resonance-imaging (MRI)-negative (or 'nonlesional') pharmacoresistant focal epilepsy are the most challenging group undergoing presurgical evaluation. Few large-scale studies have systematically reviewed the pathological substrates underlying MRI-negative epilepsies. In the current study, histopathological specimens were retrospectively reviewed from MRI-negative epilepsy patients (n=95, mean age=30 years, 50% female subjects). Focal cortical dysplasia cases were classified according to the International League Against Epilepsy (ILAE) and Palmini et al classifications. The most common pathologies found in this MRI-negative cohort included: focal cortical dysplasia (n=43, 45%), gliosis (n=21, 22%), hamartia+gliosis (n=12, 13%), and hippocampal sclerosis (n=9, 9%). The majority of focal cortical dysplasia were ILAE type I (n=37) or Palmini type I (n=39). Seven patients had no identifiable pathological abnormalities. The existence of positive pathology was not significantly associated with age or temporal/extratemporal resection. Follow-up data post surgery was available in 90 patients; 63 (70%) and 57 (63%) attained seizure freedom at 6 and 12 months, respectively. The finding of positive pathology was significantly associated with seizure-free outcome at 6 months (P=0.035), but not at 12 months. In subgroup analysis, the focal cortical dysplasia group was not significantly correlated with seizure-free outcome, as compared with the negative-pathology groups at either 6 or 12 months. Of note, the finding of hippocampal sclerosis had a significant positive correlation with seizure-free outcome when compared with the negative-pathology group (P=0.009 and 0.004 for 6- and 12-month outcome, respectively). Absence of a significant histopathology in the resected surgical specimen did not preclude seizure freedom. In conclusion, our study highlights the heterogeneity of epileptic pathologies in MRI-negative epilepsies, with focal cortical dysplasia being the most common finding. The existence of positive pathology in surgical specimen may be a good indication for short-term good seizure outcome. There is a small subset of cases in which no pathological abnormalities are identified.

0 comments Cited 36 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Contributors

Ana Carolina Coan: URI : http://frontiersin.org/people/u/82038

Marcia Elisabete Morita: URI : http://frontiersin.org/people/u/27783

Brunno Machado de Campos: URI : http://frontiersin.org/people/u/117269

Clarissa Lin Yasuda: URI : http://frontiersin.org/people/u/117849

Fernando Cendes: URI : http://frontiersin.org/people/u/8789

Journal

Journal ID (nlm-ta): Front Neurol

Journal ID (iso-abbrev): Front Neurol

Journal ID (publisher-id): Front. Neurol.

Title: Frontiers in Neurology

Publisher: Frontiers Media S.A.

ISSN (Electronic): 1664-2295

Publication date (Electronic): 25 October 2013

Publication date Collection: 2013

Volume: 4

Electronic Location Identifier: 166

Affiliations

[1] ¹Neuroimaging Laboratory, Department of Neurology, State University of Campinas , Campinas, Brazil

Author notes

Edited by: Jeremy Daniel Slater, University of Texas Medical School at Houston, USA

Reviewed by: Erik K. St. Louis, Mayo Clinic, USA; Jeffrey M. Chung, Cedars-Sinai Medical Center, USA; Dave Clarke, Dell Children’s Medical Center of Central Texas, USA

*Correspondence: Fernando Cendes, Faculdade de Ciências Médicas – UNICAMP, Departamento de Neurologia, Cidade Universitária Zeferino Vaz, Campinas, São Paulo 13083-970, Brazil e-mail: fcendes@ 123456unicamp.br

This article was submitted to Epilepsy, a section of the journal Frontiers in Neurology.

Article

DOI: 10.3389/fneur.2013.00166

PMC ID: 3829468

PubMed ID: 24298266

SO-VID: 56ec3f34-61c6-4df4-9292-68a52ce517dc

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

History

Date received : 14 June 2013

Date accepted : 12 October 2013

Page count

Figures: 2, Tables: 1, Equations: 0, References: 23, Pages: 5, Words: 3840

Comments

Comment on this article

scite_

Cited by 9

See all cited by

Most referenced authors 175

See all reference authors

- Version 1
- Version 1

Amygdala Enlargement in Patients with Mesial Temporal Lobe Epilepsy without Hippocampal Sclerosis

Read this article at

Abstract

Related collections

Stroke MRI

Most cited references 20

The role of the limbic system in experiential phenomena of temporal lobe epilepsy.

Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI.

The pathology of magnetic-resonance-imaging-negative epilepsy.

Author and article information

Contributors

Journal

Affiliations

Author notes

Article

History

Page count

Categories

Comments

Comment on this article

Similar content 271

Cited by 9

Most referenced authors 175