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Lambrecq V, Alonso I, Hasboun D, Dinkelacker V, Davachi L, Samson S, Dupont S. Memory functioning after hippocampal removal: Does side matter? J Neuropsychol 2024; 18:15-29. [PMID: 36861271 DOI: 10.1111/jnp.12309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 02/14/2023] [Indexed: 03/03/2023]
Abstract
To address the memory functioning after medial temporal lobe (MTL) surgery for refractory epilepsy and relationships with the side of the hippocampal removal, 22 patients with pharmaco-resistant epilepsy who had undergone MTL resection (10 right/12 left) at the Salpêtrière Hospital were compared with 21 matched healthy controls. We designed a specific neuropsychological binding memory test that specifically addressed hippocampal cortex functioning, and left-right material-specific lateralization. Our results showed that both left and right mesial temporal lobe removal cause a severe memory impairment, for both verbal and visual material. The removal of left medial temporal lobe causes worse memory impairment than the right removal regardless of the stimuli type (verbal or visual) questioning the theory of the hippocampal material-specific lateralization. The present study provided new evidence for the role of both hippocampus and surrounding cortices in memory-binding whatever the material type and also suggested that a left MTL removal is more deleterious for both verbal and visual episodic memory in comparison with right MTL removal.
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Affiliation(s)
- Virginie Lambrecq
- Sorbonne University, Paris, France
- Paris Brain Institute, ICM, Inserm U 1127, CNRS UMR 7225, Paris, France
- AP-HP, Neurophysiology Department, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
- AP-HP, Epilepsy Unit, Neurology Department, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
| | - Irene Alonso
- Paris Brain Institute, ICM, Inserm U 1127, CNRS UMR 7225, Paris, France
- Servicio de Salud Mental, Hospital Universitario Central de Asturias, Servicio de Salud del Principado de Asturias, Oviedo, Spain
| | - Dominique Hasboun
- Sorbonne University, Paris, France
- Service d'Anatomie, Sorbonne University, Paris, France
| | - Vera Dinkelacker
- AP-HP, Neuroradiology Department, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
- Neurology Department, Hautepierre Hospital, University of Strasbourg, Strasbourg, France
| | - Lila Davachi
- Departmentof Psychology, Columbia University, New York City, New York, USA
- Department of Clinical Research, Nathan Kline Institute for Psychiatric Research, New York City, New York, USA
| | - Séverine Samson
- Paris Brain Institute, ICM, Inserm U 1127, CNRS UMR 7225, Paris, France
- AP-HP, Epilepsy Unit, Neurology Department, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
- ULR 4072 - PSITEC - Department of Psychology: Interactions, Temps, Emotions, Cognition, University of Lille, Lille, France
| | - Sophie Dupont
- Sorbonne University, Paris, France
- Paris Brain Institute, ICM, Inserm U 1127, CNRS UMR 7225, Paris, France
- AP-HP, Epilepsy Unit, Neurology Department, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
- Service d'Anatomie, Sorbonne University, Paris, France
- Rehabilitation Unit, APHP Sorbonne, Pitie-Salpetriere Hospital, Paris, France
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Baxendale S. Sex differences in the pre and postoperative neuropsychological function of epilepsy surgery candidates. Clin Neuropsychol 2023:1-13. [PMID: 37975582 DOI: 10.1080/13854046.2023.2281706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023]
Abstract
Objective: As programs expand globally, epilepsy surgery is becoming increasingly available as an effective treatment for some people with medically intractable seizures. Prospective candidates require careful neuropsychological evaluation and follow-up. The aim of this study was to examine the sex differences in neuropsychological function in presurgical presentation and postoperative outcomes in people with temporal lobe epilepsy referred for epilepsy surgery. Methods: Three hundred and seventy-two patients (202 Female; 170 Male) with a homogenous underlying pathology (hippocampal sclerosis) underwent a preoperative assessment on tests of intellectual, language, and memory function and were followed up one year after undergoing a unilateral temporal lobe resection; n = 169 Right (RTL), n = 203 Left (LTL). Results: There was no impact of sex or laterality of surgery on seizure outcome; 84% of males and 80% of females were seizure free at follow-up. Before surgery, sex effects were evident on tests of verbal memory with females performing better than males. Declines in verbal memory function following surgery were greater in females than males. Being female had a stronger association with postoperative decline on immediate prose recall (partial eta squared η2 = 0.029), than side of surgery (η2 = 0.018) albeit with a small effect size. Conclusions: There are subtle but significant sex differences in the neuropsychological profiles of people with temporal lobe epilepsy, before and following surgery. Whilst females generally perform better than males on tests of verbal memory function before surgery they demonstrate greater post-operative declines on these measures following surgery.
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Affiliation(s)
- Sallie Baxendale
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- University College Hospital, London, UK
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Smetana RM, Batchala PP, Lee BG, Albataineh T, Broshek DK, Fountain NB, Abbas S, Quigg M. Multifocal hypometabolic correlates to deficits of verbal memory in mesial temporal lobe epilepsy. Epilepsy Behav 2023; 143:109244. [PMID: 37192585 DOI: 10.1016/j.yebeh.2023.109244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/26/2023] [Accepted: 04/27/2023] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND OBJECTIVES Neuropsychological research on mesial temporal lobe epilepsy (MTLE) often highlights material-specific memory deficits, but a lesion-focused model may not accurately reflect the underlying networks that support episodic memory in these patients. Our study evaluated the pathophysiology behind verbal learning/memory deficits as revealed by hypometabolism quantified through 18-fluorodeoxyglucose positron emission tomography (FDG-PET). METHODS This retrospective study included thirty presurgical patients with intractable unilateral MTLE who underwent interictal FDG-PET and verbal memory assessment (12 females, mean age: 38.73 years). Fluorodeoxyglucose-positron emission tomography mapping was performed with voxel-based mapping of glucose utilization to a database of age-matched controls to derive regional Z-scores. Neuropsychological outcome variables included scores on learning and recall trials of two distinct verbal memory measures validated for use in epilepsy research. Pearson's correlations evaluated relationships between clinical variables and verbal memory. Linear regression was used to relate regional hypometabolism and verbal memory assessment. Post hoc analyses assessed areas of FDG-PET hypometabolism (threshold Z ≤ -1.645 below mean) where verbal memory was impaired. RESULTS Verbal memory deficits correlated with hypometabolism in limbic structures ipsilateral to language dominance but also correlated with hypometabolism in networks involving the ipsilateral perisylvian cortex and contralateral limbic and nonlimbic structures. DISCUSSION We conclude that traditional models of verbal memory may not adequately capture cognitive deficits in a broader sample of patients with MTLE. This study has important implications for epilepsy surgery protocols that use neuropsychological data and FDG-PET to draw conclusions about surgical risks.
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Affiliation(s)
- Racheal M Smetana
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA.
| | - Prem P Batchala
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA.
| | - Bern G Lee
- Department of Neuropsychology, Ochsner Health, Baton Rouge, LA, USA.
| | - Tamer Albataineh
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA.
| | - Donna K Broshek
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, USA.
| | - Nathan B Fountain
- Comprehensive Epilepsy Program, Department of Neurology, University of Virginia, Charlottesville, VA, USA.
| | - Salma Abbas
- Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, USA.
| | - Mark Quigg
- Comprehensive Epilepsy Program, Department of Neurology, University of Virginia, Charlottesville, VA, USA.
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Rijnders B, Korkmaz EE, Yildirim F. Hybrid machine learning method for a connectivity-based epilepsy diagnosis with resting-state EEG. Med Biol Eng Comput 2022; 60:1675-1689. [DOI: 10.1007/s11517-022-02560-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
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Strýček O, Lamoš M, Rektor I. Memory retrieval in temporal lobe epilepsy is related to functional segregation of the mesiotemporal structures. Epilepsy Behav 2021; 122:108196. [PMID: 34256340 DOI: 10.1016/j.yebeh.2021.108196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/16/2021] [Accepted: 06/24/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE We analyzed the impact of temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) on functional connectivity (FC) between mesiotemporal structures. Functional connectivity modifications related to word retrieval were investigated. METHODS High-density EEG of 21 patients with TLE with HS (12 left TLE and 9 right TLE) and 10 healthy controls (HCs) were recorded during a verbal subsequent memory paradigm. Electroencephalography data were reconstructed into the source space and FC was calculated from the source activity of regions of interest. RESULTS A significant decrease in FC between the right- and left-sided mesiotemporal structures in TLE was observed. The decrease was significant only with words that were correctly recognized. The decrease in interhemispheric FC between mesiotemporal structures was found in the 8- to 20-Hz frequency range in both left and right TLE. SIGNIFICANCE The decreased FC between the mesiotemporal structures in TLE is a condition for successful performance of a memory retrieval task. The successful memory retrieval in TLE is related to functional segregation of lesional from nonlesional mesiotemporal structures. This decrease was absent in non-successful responses.
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Affiliation(s)
- Ondřej Strýček
- First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brain and Mind Research Program, Brno, Czech Republic
| | - Martin Lamoš
- Central European Institute of Technology (CEITEC), Masaryk University, Brain and Mind Research Program, Brno, Czech Republic
| | - Ivan Rektor
- First Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Central European Institute of Technology (CEITEC), Masaryk University, Brain and Mind Research Program, Brno, Czech Republic.
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Doll A, Wegrzyn M, Benzait A, Mertens M, Woermann FG, Labudda K, Bien CG, Kissler J. Whole-brain functional correlates of memory formation in mesial temporal lobe epilepsy. Neuroimage Clin 2021; 31:102723. [PMID: 34147817 PMCID: PMC8220377 DOI: 10.1016/j.nicl.2021.102723] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/06/2021] [Accepted: 06/07/2021] [Indexed: 11/29/2022]
Abstract
Large study of encoding and subsequent memory for words, faces, and scenes. Less ipsilateral mesial temporal activity in mesial temporal lobe epilepsy (mTLE). Extra-mTL activity in mTLE only partly relevant for memory formation. Across materials contralateral mTL decisive to maintain intact memory in mTLE. Left frontal activation correlates with better verbal memory only in left mTLE.
The mesial temporal lobe is a key region for episodic memory. Accordingly, memory impairment is frequent in patients with mesial temporal lobe epilepsy. However, the functional relevance of potentially epilepsy-induced reorganisation for memory formation is still not entirely clear. Therefore, we investigated whole-brain functional correlates of verbal and non-verbal memory encoding and subsequent memory formation in 56 (25 right sided) mesial temporal lobe epilepsy patients and 21 controls. We applied an fMRI task of learning scenes, faces, and words followed by an out-of-scanner recognition test. During encoding of faces and scenes left and right mesial temporal lobe epilepsy patients had consistently reduced activation in the epileptogenic mesial temporal lobe compared with controls. Activation increases in patients were apparent in extra-temporal regions, partly associated with subsequent memory formation (left frontal regions and basal ganglia), and patients had less deactivation in regions often linked to the default mode and auditory networks. The more specific subsequent memory contrast indicated only marginal group differences. Correlating patients’ encoding activation with memory performance both within the paradigm and with independent clinical measures demonstrated predominantly increased contralateral mesio-temporal activation supporting intact memory performance. In left temporal lobe epilepsy patients, left frontal activation was also correlated with better verbal memory performance. Taken together, our findings hint towards minor extra-temporal plasticity in mesial temporal lobe epilepsy patients, which is in line with pre-surgical impairment and post-surgical memory decline in many patients. Further, data underscore the importance of particularly the contralateral mesial temporal lobe itself, to maintain intact memory performance.
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Affiliation(s)
- Anna Doll
- Bielefeld University, Medical School, Department of Epileptology (Krankenhaus Mara), Maraweg 21, Bielefeld 33617, Germany; Bielefeld University, Department of Psychology, Universitätsstraße 25, Bielefeld 33615, Germany.
| | - Martin Wegrzyn
- Bielefeld University, Department of Psychology, Universitätsstraße 25, Bielefeld 33615, Germany
| | - Anissa Benzait
- Bielefeld University, Medical School, Department of Epileptology (Krankenhaus Mara), Maraweg 21, Bielefeld 33617, Germany; Bielefeld University, Department of Psychology, Universitätsstraße 25, Bielefeld 33615, Germany
| | - Markus Mertens
- Bielefeld University, Medical School, Department of Epileptology (Krankenhaus Mara), Maraweg 21, Bielefeld 33617, Germany
| | - Friedrich G Woermann
- Bielefeld University, Medical School, Department of Epileptology (Krankenhaus Mara), Maraweg 21, Bielefeld 33617, Germany
| | - Kirsten Labudda
- Bielefeld University, Department of Psychology, Universitätsstraße 25, Bielefeld 33615, Germany
| | - Christian G Bien
- Bielefeld University, Medical School, Department of Epileptology (Krankenhaus Mara), Maraweg 21, Bielefeld 33617, Germany
| | - Johanna Kissler
- Bielefeld University, Department of Psychology, Universitätsstraße 25, Bielefeld 33615, Germany; Center for Cognitive Interaction Technology (CITEC), University of Bielefeld, Inspiration 1, Bielefeld 33619, Germany
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Barrett Jones S, A Miller L, Kleitman S, Nikpour A, Lah S. Semantic and episodic memory in adults with temporal lobe epilepsy. Appl Neuropsychol Adult 2021; 29:1352-1361. [PMID: 33595395 DOI: 10.1080/23279095.2021.1876692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The primary aims were to (1) identify the factor structure of tests thought to measure semantic and episodic memory and (2) examine whether patterns of impairment would show a double dissociation between these two memory systems at an individual level in patients with temporal lobe epilepsy (TLE). The secondary aim was to explore the impact of epilepsy-related variables on performance. This retrospective study involved a cohort of 54 adults who had been diagnosed with TLE and had undergone a neuropsychological assessment that included four memory tests traditionally used to measure either semantic memory (picture naming, animal fluency) or episodic memory (story recall, word list recall) at a single epilepsy surgery center in Australia. Principal component analysis revealed two factors albeit with unexpected loadings. Picture naming and story recall loaded on one factor. Animal fluency and word list recall loaded on another factor. There was no evidence of a double dissociation between semantic and episodic memory at an individual level. Left hemisphere seizure focus and early age of seizure onset related to worse performance on word list recall, picture naming and animal fluency, respectively. Our study highlights the importance of caution when interpreting the results of neuropsychological assessments, as not all putative tests of semantic and episodic memory may necessarily be measuring the same construct. Future directions for research are also considered.
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Affiliation(s)
| | - Laurie A Miller
- Central Clinical School, University of Sydney, New South Wales, Australia
| | - Sabina Kleitman
- School of Psychology, University of Sydney, Sydney, Australia
| | - Armin Nikpour
- Central Clinical School, University of Sydney, New South Wales, Australia.,University of Sydney, Sydney, Australia
| | - Suncica Lah
- School of Psychology, University of Sydney, Sydney, Australia
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Phuong TH, Houot M, Méré M, Denos M, Samson S, Dupont S. Cognitive impairment in temporal lobe epilepsy: contributions of lesion, localization and lateralization. J Neurol 2020; 268:1443-1452. [PMID: 33216221 DOI: 10.1007/s00415-020-10307-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 11/05/2020] [Accepted: 11/08/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Cognitive impairment is an important comorbidity of refractory temporal lobe epilepsy (TLE). We aimed to explore the impact of (i) specific lesions, such as dysembryoplastic neuroepithelial tumor (DNET), dysplasia, or hippocampal sclerosis, (ii) focus localization (medial versus lateral) and (iii) focus lateralization (right versus left) on the neuropsychological profile of refractory TLE adult patients. METHODS We examined the neuropsychological characteristics of 312 adults with refractory TLE: 100 patients without hippocampal sclerosis (HS) and 212 with HS. Scores on tests of intelligence (Global IQ, Verbal IQ and Performance IQ), working memory, episodic memory (verbal and visual learning and forgetting), executive functions and language abilities were analyzed. RESULTS Three main factors influenced the neuropsychological profile of refractory TLE patients: (i) the lesion, patients with HS obtaining poorer cognitive performances than patients without HS and specifically DNET patients performing better than patients with HS, (ii) the focus side, that seems only relevant for verbal memory abilities which are affected in left but not right TLE patients and (iii) the localization of seizure focus, patients with medial TLE exhibiting lower memory performances than patients with lateral TLE. CONCLUSION Lesion, localization and lateralization are major contributors of the cognitive impairment depicted in TLE. Hippocampal sclerosis appears as the main contributor.
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Affiliation(s)
- Thanh Ha Phuong
- Rehabilitation Unit, AP-HP, Pitié-Salpêtrière Hospital, Paris, France.,Neurology Unit, Hôpital Bach Mai, Hanoi, Vietnam
| | - Marion Houot
- Clinical Investigation Centre, Institut du Cerveau Et de La Moelle Épinière (ICM), Pitié-Salpêtrière Hospital Paris, Paris, France.,Department of Neurology, Institute of Memory and Alzheimer's Disease (IM2A), AP-HP, Pitié-Salpêtrière Hospital, Paris, France.,Centre of Excellence of Neurodegenerative Disease (CoEN), AP-HP, Pitié-Salpêtrière Hospital, Paris, France
| | - Marie Méré
- Epilepsy Unit, AP-HP, Pitié-Salpêtrière Hospital, Paris, France
| | - Marisa Denos
- Rehabilitation Unit, AP-HP, Pitié-Salpêtrière Hospital, Paris, France
| | - Séverine Samson
- Univ. Lille, ULR 4072-PSITEC-Psychologie: Interactions Temps Émotions Cognition, F-59000, Lille, France
| | - Sophie Dupont
- Rehabilitation Unit, AP-HP, Pitié-Salpêtrière Hospital, Paris, France. .,Epilepsy Unit, AP-HP, Pitié-Salpêtrière Hospital, Paris, France. .,Université Paris Sorbonne, Paris, France. .,Centre de Recherche de l'Institut du Cerveau Et de La Moelle Épinière (ICM), UMPC-UMR 7225 CNRS-UMRS 975 Inserm, Paris, France.
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Fallahi A, Pooyan M, Lotfi N, Baniasad F, Tapak L, Mohammadi-Mobarakeh N, Hashemi-Fesharaki SS, Mehvari-Habibabadi J, Ay MR, Nazem-Zadeh MR. Dynamic functional connectivity in temporal lobe epilepsy: a graph theoretical and machine learning approach. Neurol Sci 2021; 42:2379-90. [PMID: 33052576 DOI: 10.1007/s10072-020-04759-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 09/23/2020] [Indexed: 12/11/2022]
Abstract
PURPOSE Functional magnetic resonance imaging (fMRI) in resting state can be used to evaluate the functional organization of the human brain in the absence of any task or stimulus. The functional connectivity (FC) has non-stationary nature and consented to be varying over time. By considering the dynamic characteristics of the FC and using graph theoretical analysis and a machine learning approach, we aim to identify the laterality in cases of temporal lobe epilepsy (TLE). METHODS Six global graph measures are extracted from static and dynamic functional connectivity matrices using fMRI data of 35 unilateral TLE subjects. Alterations in the time trend of the graph measures are quantified. The random forest (RF) method is used for the determination of feature importance and selection of dynamic graph features including mean, variance, skewness, kurtosis, and Shannon entropy. The selected features are used in the support vector machine (SVM) classifier to identify the left and right epileptogenic sides in patients with TLE. RESULTS Our results for the performance of SVM demonstrate that the utility of dynamic features improves the classification outcome in terms of accuracy (88.5% for dynamic features compared with 82% for static features). Selecting the best dynamic features also elevates the accuracy to 91.5%. CONCLUSION Accounting for the non-stationary characteristics of functional connectivity, dynamic connectivity analysis of graph measures along with machine learning approach can identify the temporal trend of some specific network features. These network features may be used as potential imaging markers in determining the epileptogenic hemisphere in patients with TLE.
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Roger E, Torlay L, Gardette J, Mosca C, Banjac S, Minotti L, Kahane P, Baciu M. A machine learning approach to explore cognitive signatures in patients with temporo-mesial epilepsy. Neuropsychologia 2020; 142:107455. [DOI: 10.1016/j.neuropsychologia.2020.107455] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/25/2020] [Accepted: 03/27/2020] [Indexed: 12/18/2022]
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Iida K, Kagawa K, Katagiri M, Seyama G, Hashizume A, Abiko M, Katayama J, Suzuki H, Kurisu K, Otsubo H. Preservation of Memory Despite Unresected Contralateral Hippocampal Volume Loss After Resection of Hippocampal Sclerosis in Seizure-Free Patients. World Neurosurg 2019; 132:e759-e765. [PMID: 31415886 DOI: 10.1016/j.wneu.2019.08.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/03/2019] [Accepted: 08/03/2019] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To determine postoperative long-term changes of hippocampal volume (HV) correlating with cognitive functions in patients who underwent surgery for hippocampal sclerosis with postoperative freedom from seizures. METHODS We studied 1.5T magnetic resonance imaging before and after surgery in 24 patients (mean ± SD age, 36.9 ± 11.0 years) with hippocampal sclerosis. We performed serial magnetic resonance imaging at 6 months to 1 year, 1-2 years, 2-3 years, and 3-5 years postoperatively. We compared HVs of 24 patients with HVs of 14 age-matched control subjects. We analyzed correlations between consecutive HVs and seizure duration and age at surgery. We compared consecutive changes in HVs between dominant and nondominant hemispheres with concurrent cognitive functions. RESULTS Preoperative HVs of unresected contralateral hippocampus were significantly smaller than HVs of control subjects (P < 0.01). Unresected contralateral HV changes compared with preoperative HVs were -3.6% ± 6.9%, -2.3% ± 8.5%, -3.6% ± 10.2% (P < 0.05), and -5.0% ± 9.5% (P < 0.05) at consecutive postoperative periods. Largest change in HVs at 3-5 years was significantly correlated with older age at surgery (P < 0.05). Unresected contralateral dominant 14 HVs remained consistently smaller than nondominant 10 HVs up to 5 years with statistical significance (P < 0.05). Verbal memory was preserved in 14 patients with unresected contralateral smaller dominant hippocampus. CONCLUSIONS In seizure-free patients after hippocampal sclerosis resection , unresected contralateral HV significantly declined with older age at surgery. Visual memory was preserved regardless of side and volume loss. Despite significantly reduced HVs, verbal memory was preserved with the unresected contralateral dominant hippocampus. Earlier surgical intervention may have lower potential risk for memory decline secondary to postoperative HV loss.
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Affiliation(s)
- Koji Iida
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Epilepsy Center, Hiroshima University Hospital, Hiroshima, Japan.
| | - Kota Kagawa
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Epilepsy Center, Hiroshima University Hospital, Hiroshima, Japan
| | - Masaya Katagiri
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Epilepsy Center, Hiroshima University Hospital, Hiroshima, Japan
| | - Go Seyama
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Epilepsy Center, Hiroshima University Hospital, Hiroshima, Japan
| | - Akira Hashizume
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Epilepsy Center, Hiroshima University Hospital, Hiroshima, Japan
| | - Masaru Abiko
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Junko Katayama
- Division of Radiology, Hiroshima Chuo-Kenshin-Sho, Hiroshima, Japan
| | - Hiroharu Suzuki
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Kaoru Kurisu
- Department of Neurosurgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hiroshi Otsubo
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
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Fallahi A, Nazem-Zadeh MR, Baniasad F, Lotfi N, Mirbagheri M, Mohammadi-Mobarakeh N, Tapak L, Hashemi-Fesharaki SS, Pooyan M, Mehvari-Habibabadi J. Evolution of Graph Theory in Dynamic Functional Connectivity for Lateralization of Temporal Lobe Epilepsy. Annu Int Conf IEEE Eng Med Biol Soc 2019; 2019:628-631. [PMID: 31945976 DOI: 10.1109/embc.2019.8856717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Resting-state functional magnetic resonance imaging (rsfMRI) has described the functional architecture of the human brain in the absence of any task or stimulus. Since the functional connectivity (FC), has non-stationary nature, it is evidenced to be varying over time. Using dynamic functional connectivity, six graph theoretical characteristics were measured and compared between left and right temporal lobe epilepsy (TLE). We also obtain a trend for each characteristic in the time course of experiments. The results demonstrated that the static connectivity analysis failed to fully separate the left and right TLE patients for some characteristics, whereby the dynamic analysis has been shown capable of identifying the laterality. Furthermore, the results suggest that the temporal trend of some graph theoretical characteristics can be exploited as a novel marker for TLE laterality.
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Cahill V, Sinclair B, Malpas CB, McIntosh AM, Chen Z, Vivash LE, O'Shea MF, Wilson SJ, Desmond PM, Berlangieri SU, Hicks RJ, Rowe CC, Morokoff AP, King JA, Fabinyi GC, Kaye AH, Kwan P, Berkovic SF, O'Brien TJ. Metabolic patterns and seizure outcomes following anterior temporal lobectomy. Ann Neurol 2019; 85:241-250. [DOI: 10.1002/ana.25405] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/22/2018] [Accepted: 12/24/2018] [Indexed: 01/21/2023]
Affiliation(s)
- Varduhi Cahill
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Manchester Centre for Clinical Neurosciences; Salford Royal NHS Foundation Trust; Salford United Kingdom
- Division of Neuroscience and Experimental Psychology; School of Biological Sciences, University of Manchester; Manchester United Kingdom
| | - Benjamin Sinclair
- Departments of Medicine and Radiology; University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
| | - Charles B. Malpas
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
- Murdoch Children's Research Institute; Melbourne Victoria Australia
- Melbourne School of Psychological Sciences; University of Melbourne; Melbourne Victoria Australia
| | - Anne M. McIntosh
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
- Epilepsy Research Centre; University of Melbourne, Austin Hospital; Melbourne Victoria Australia
| | - Zhibin Chen
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
| | - Lucy E. Vivash
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
| | - Marie F. O'Shea
- Comprehensive Epilepsy Program; Austin Hospital; Melbourne Victoria Australia
| | - Sarah J. Wilson
- Melbourne School of Psychological Sciences; University of Melbourne; Melbourne Victoria Australia
- Comprehensive Epilepsy Program; Austin Hospital; Melbourne Victoria Australia
| | - Patricia M. Desmond
- Departments of Medicine and Radiology; University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
| | | | - Rodney J. Hicks
- Peter MacCallum Cancer Centre and the Sir Peter MacCallum Department of Oncology; University of Melbourne; Melbourne Victoria Australia
| | - Christopher C. Rowe
- Epilepsy Research Centre; University of Melbourne, Austin Hospital; Melbourne Victoria Australia
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Melbourne Victoria Australia
| | - Andrew P. Morokoff
- Department of Surgery; University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
| | - James A. King
- Department of Surgery; University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
| | - Gavin C. Fabinyi
- Department of Surgery; University of Melbourne, Austin Hospital; Melbourne Victoria Australia
| | - Andrew H. Kaye
- Department of Surgery; University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
| | - Patrick Kwan
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
| | - Samuel F. Berkovic
- Epilepsy Research Centre; University of Melbourne, Austin Hospital; Melbourne Victoria Australia
- Comprehensive Epilepsy Program; Austin Hospital; Melbourne Victoria Australia
| | - Terence J. O'Brien
- Departments of Medicine and Neurology; Melbourne Brain Centre, University of Melbourne, Royal Melbourne Hospital; Melbourne Victoria Australia
- Departments of Neuroscience and Neurology; Alfred Health, Central Clinical School, Monash University; Melbourne Victoria Australia
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Frank B, Hurley L, Scott TM, Olsen P, Dugan P, Barr WB. Machine learning as a new paradigm for characterizing localization and lateralization of neuropsychological test data in temporal lobe epilepsy. Epilepsy Behav 2018; 86:58-65. [PMID: 30082202 DOI: 10.1016/j.yebeh.2018.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/05/2018] [Accepted: 07/05/2018] [Indexed: 10/28/2022]
Abstract
In this study, we employed a kernel support vector machine to predict epilepsy localization and lateralization for patients with a diagnosis of epilepsy (n = 228). We assessed the accuracy to which indices of verbal memory, visual memory, verbal fluency, and naming would localize and lateralize seizure focus in comparison to standard electroencephalogram (EEG). Classification accuracy was defined as models that produced the least cross-validated error (CVϵ). In addition, we assessed whether the inclusion of norm-based standard scores, demographics, and emotional functioning data would reduce CVϵ. Finally, we obtained class probabilities (i.e., the probability of a particular classification for each case) and produced receiver operating characteristic (ROC) curves for the primary analyses. We obtained the least error assessing localization data with the Gaussian radial basis kernel function (RBF; support vectors = 157, CVϵ = 0.22). There was no overlap between the localization and lateralization models, such that the poorest localization model (the hyperbolic tangent kernel function; support vectors = 91, CVϵ = 0.36) outperformed the strongest lateralization model (RBF; support vectors = 201, CVϵ = 0.39). Contrary to our hypothesis, the addition of norm, demographics, and emotional functioning data did not improve the accuracy of the models. Receiver operating characteristic curves suggested clinical utility in classifying epilepsy lateralization and localization using neuropsychological indicators, albeit with better discrimination for localizing determinations. This study adds to the existing literature by employing an analytic technique with inherent advantages in generalizability when compared to traditional single-sample, not cross-validated models. In the future, class probabilities extracted from these and similar analyses could supplement neuropsychological practice by offering a quantitative guide to clinical judgements.
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Affiliation(s)
- Brandon Frank
- Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States of America
| | - Landon Hurley
- Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States of America
| | - Travis M Scott
- Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States of America
| | - Pat Olsen
- Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States of America
| | - Patricia Dugan
- Department of Neurology, NYU School of Medicine, New York, NY 10016, United States of America
| | - William B Barr
- Department of Neurology, NYU School of Medicine, New York, NY 10016, United States of America.
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Výtvarová E, Mareček R, Fousek J, Strýček O, Rektor I. Large-scale cortico-subcortical functional networks in focal epilepsies: The role of the basal ganglia. Neuroimage Clin 2016; 14:28-36. [PMID: 28123951 PMCID: PMC5222946 DOI: 10.1016/j.nicl.2016.12.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 11/02/2016] [Accepted: 12/15/2016] [Indexed: 12/02/2022]
Abstract
Objectives The aim was to describe the contribution of basal ganglia (BG) thalamo-cortical circuitry to the whole-brain functional connectivity in focal epilepsies. Methods Interictal resting-state fMRI recordings were acquired in 46 persons with focal epilepsies. Of these 46, 22 had temporal lobe epilepsy: 9 left temporal (LTLE), 13 right temporal (RTLE); 15 had frontal lobe epilepsy (FLE); and 9 had parietal/occipital lobe epilepsy (POLE). There were 20 healthy controls. The complete weighted network was analyzed based on correlation matrices of 90 and 194 regions. The network topology was quantified on a global and regional level by measures based on graph theory, and connection-level changes were analyzed by the partial least square method. Results In all patient groups except RTLE, the shift of the functional network topology away from random was observed (normalized clustering coefficient and characteristic path length were higher in patient groups than in controls). Links contributing to this change were found in the cortico-subcortical connections. Weak connections (low correlations) consistently contributed to this modification of the network. The importance of regions changed: decreases in the subcortical areas and both decreases and increases in the cortical areas were observed in node strength, clustering coefficient and eigenvector centrality in patient groups when compared to controls. Node strength decreases of the basal ganglia, i.e. the putamen, caudate, and pallidum, were displayed in LTLE, FLE, and POLE. The connectivity within the basal ganglia–thalamus circuitry was not disturbed; the disturbance concerned the connectivity between the circuitry and the cortex. Significance Focal epilepsies affect large-scale brain networks beyond the epileptogenic zones. Cortico-subcortical functional connectivity disturbance was displayed in LTLE, FLE, and POLE. Significant changes in the resting-state functional connectivity between cortical and subcortical structures suggest an important role of the BG and thalamus in focal epilepsies. Focal epilepsies affect large-scale brain networks beyond the epileptogenic zones. The functional network topology shifted away from random in focal epilepsies. Subcortico-cortical connectivity decreased in epilepsy due to changes in weak links. Basal ganglia–thalamus circuitry connectivity was not disturbed in focal epilepsy. The connectivity between basal ganglia-thalamus circuitry and cortex was affected.
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Affiliation(s)
- Eva Výtvarová
- Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Radek Mareček
- Brain and Mind Research Program, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Jan Fousek
- Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Ondřej Strýček
- Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital, Faculty of Medicine, Masaryk University, Pekařská 53, 656 91 Brno, Czech Republic; Brain and Mind Research Program, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Ivan Rektor
- Brno Epilepsy Center, First Department of Neurology, St. Anne's University Hospital, Faculty of Medicine, Masaryk University, Pekařská 53, 656 91 Brno, Czech Republic; Brain and Mind Research Program, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
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Abstract
SummaryIntroduction.Medial temporal lobe epilepsy (MTLE) is the most frequent form of epilepsy in adulthood. It is classified as local/regional epilepsy. However, there is increasing evidence of the involvement of both temporal lobes and this provides abundant arguments to question this view, and consider MTLE as one of the typical bilateral system epilepsies.Aim.To provide a contemporary review of medial temporal lobe epilepsy, discussing the bilateral aspects, with reference to epilepsy surgery.Methods.A literature review and a resume of the author’s own experiences with MTLE patients.Results.Recent electrophysiological and neuroimaging data provide convincing data supporting that MTLE is a bilateral disease. The uni-and bilateral features form a continuum and the participation rate of the two temporal lobes determine course and surgical perspective of the individual patient.Conclusions.The contradictory data of invasive presurgical evaluations of MTLE patients suggest that there need to identify further indicatory markers of bilaterality and thus change the presurgical evaluation from the non-invasive towards the invasive ways. The mechanisms of the interrelationship between the two temporal lobes in MTLE warrants further research.
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Coito A, Michel CM, van Mierlo P, Vulliemoz S, Plomp G. Directed Functional Brain Connectivity Based on EEG Source Imaging: Methodology and Application to Temporal Lobe Epilepsy. IEEE Trans Biomed Eng 2016; 63:2619-2628. [PMID: 27775899 DOI: 10.1109/tbme.2016.2619665] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE The importance of functional brain connectivity to study physiological and pathological brain activity has been widely recognized. Here, we aimed to 1) review a methodological pipeline to investigate directed functional connectivity between brain regions using source signals derived from high-density EEG; 2) elaborate on some methodological challenges; and 3) apply this pipeline to temporal lobe epilepsy (TLE) patients and healthy controls to investigate directed functional connectivity differences in the theta and beta frequency bands during EEG epochs without visible pathological activity. METHODS The methodological pipeline includes: EEG acquisition and preprocessing, electrical-source imaging (ESI) using individual head models and distributed inverse solutions, parcellation of the gray matter in regions of interest, fixation of the dipole orientation for each region, computation of the spectral power in the source space, and directed functional connectivity estimation using Granger-causal modeling. We specifically analyzed how the signal-to-noise ratio (SNR) changes using different approaches for the dipole orientation fixation. We applied this pipeline to 20 left TLE patients, 20 right TLE patients, and 20 healthy controls. RESULTS Projecting each dipole to the predominant dipole orientation leads to a threefold SNR increase as compared to the norm of the dipoles. By comparing connectivity in TLE versus controls, we found significant frequency-specific outflow differences in physiologically plausible regions. CONCLUSION The results suggest that directed functional connectivity derived from ESI can help better understand frequency-specific resting-state network alterations underlying focal epilepsy. SIGNIFICANCE EEG-based directed functional connectivity could contribute to the search of new biomarkers of this disorder.
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Coito A, Genetti M, Pittau F, Iannotti GR, Thomschewski A, Höller Y, Trinka E, Wiest R, Seeck M, Michel CM, Plomp G, Vulliemoz S. Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study. Epilepsia 2016; 57:402-11. [DOI: 10.1111/epi.13308] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2015] [Indexed: 12/01/2022]
Affiliation(s)
- Ana Coito
- Functional Brain Mapping Lab; Department of Fundamental Neurosciences; University of Geneva; Geneva Switzerland
| | - Melanie Genetti
- Functional Brain Mapping Lab; Department of Fundamental Neurosciences; University of Geneva; Geneva Switzerland
| | - Francesca Pittau
- EEG and Epilepsy Unit; University Hospital of Geneva; Geneva Switzerland
| | - Giannina R. Iannotti
- Functional Brain Mapping Lab; Department of Fundamental Neurosciences; University of Geneva; Geneva Switzerland
| | - Aljoscha Thomschewski
- Department of Neurology; Paracelsus Medical University and Center for Cognitive Neuroscience; Salzburg Austria
| | - Yvonne Höller
- Department of Neurology; Paracelsus Medical University and Center for Cognitive Neuroscience; Salzburg Austria
| | - Eugen Trinka
- Department of Neurology; Paracelsus Medical University and Center for Cognitive Neuroscience; Salzburg Austria
| | - Roland Wiest
- Institute for Diagnostic and Interventional Neuroradiology; University of Bern; Bern Switzerland
| | - Margitta Seeck
- EEG and Epilepsy Unit; University Hospital of Geneva; Geneva Switzerland
| | - Christoph M. Michel
- Functional Brain Mapping Lab; Department of Fundamental Neurosciences; University of Geneva; Geneva Switzerland
| | - Gijs Plomp
- Functional Brain Mapping Lab; Department of Fundamental Neurosciences; University of Geneva; Geneva Switzerland
- Department of Psychology; University of Fribourg; Fribourg Switzerland
| | - Serge Vulliemoz
- EEG and Epilepsy Unit; University Hospital of Geneva; Geneva Switzerland
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Sidhu MK, Stretton J, Winston GP, McEvoy AW, Symms M, Thompson PJ, Koepp MJ, Duncan JS. Memory network plasticity after temporal lobe resection: a longitudinal functional imaging study. Brain 2016; 139:415-30. [PMID: 26754787 PMCID: PMC4805088 DOI: 10.1093/brain/awv365] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 10/30/2015] [Indexed: 11/13/2022] Open
Abstract
Anterior temporal lobe resection can control seizures in up to 80% of patients with temporal lobe epilepsy. Memory decrements are the main neurocognitive complication. Preoperative functional reorganization has been described in memory networks, but less is known of postoperative reorganization. We investigated reorganization of memory-encoding networks preoperatively and 3 and 12 months after surgery. We studied 36 patients with unilateral medial temporal lobe epilepsy (19 right) before and 3 and 12 months after anterior temporal lobe resection. Fifteen healthy control subjects were studied at three equivalent time points. All subjects had neuropsychological testing at each of the three time points. A functional magnetic resonance imaging memory-encoding paradigm of words and faces was performed with subsequent out-of-scanner recognition assessments. Changes in activations across the time points in each patient group were compared to changes in the control group in a single flexible factorial analysis. Postoperative change in memory across the time points was correlated with postoperative activations to investigate the efficiency of reorganized networks. Left temporal lobe epilepsy patients showed increased right anterior hippocampal and frontal activation at both 3 and 12 months after surgery relative to preoperatively, for word and face encoding, with a concomitant reduction in left frontal activation 12 months postoperatively. Right anterior hippocampal activation 12 months postoperatively correlated significantly with improved verbal learning in patients with left temporal lobe epilepsy from preoperatively to 12 months postoperatively. Preoperatively, there was significant left posterior hippocampal activation that was sustained 3 months postoperatively at word encoding, and increased at face encoding. For both word and face encoding this was significantly reduced from 3 to 12 months postoperatively. Patients with right temporal lobe epilepsy showed increased left anterior hippocampal activation on word encoding from 3 to 12 months postoperatively compared to preoperatively. On face encoding, left anterior hippocampal activations were present preoperatively and 12 months postoperatively. Left anterior hippocampal and orbitofrontal cortex activations correlated with improvements in both design and verbal learning 12 months postoperatively. On face encoding, there were significantly increased left posterior hippocampal activations that reduced significantly from 3 to 12 months postoperatively. Postoperative changes occur in the memory-encoding network in both left and right temporal lobe epilepsy patients across both verbal and visual domains. Three months after surgery, compensatory posterior hippocampal reorganization that occurs is transient and inefficient. Engagement of the contralateral hippocampus 12 months after surgery represented efficient reorganization in both patient groups, suggesting that the contralateral hippocampus contributes to memory outcome 12 months after surgery.
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Affiliation(s)
- Meneka K Sidhu
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - Jason Stretton
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK 3 MRC Cognition and Brain Science Unit, Chaucer Road, Cambridge, CB2 7EF, UK
| | - Gavin P Winston
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - Andrew W McEvoy
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - Mark Symms
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - Pamela J Thompson
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - Matthias J Koepp
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
| | - John S Duncan
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK 2 Epilepsy Society MRI Unit, Chesham Lane, Chalfont St. Peter SL9 0RJ, Buckinghamshire, UK
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Li H, Fan W, Yang J, Song S, Liu Y, Lei P, Shrestha L, Mella G, Chen W, Xu H. Asymmetry in cross-hippocampal connectivity in unilateral mesial temporal lobe epilepsy. Epilepsy Res 2015; 118:14-21. [PMID: 26561924 DOI: 10.1016/j.eplepsyres.2015.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/15/2015] [Accepted: 10/25/2015] [Indexed: 01/06/2023]
Abstract
Mesial temporal lobe epilepsy (mTLE) is mostly characterized by hippocampal sclerosis (HS) changes. Although considerable progress has been made in understanding the altered functional network of mTLE patients, whether one side of the abnormal hippocampal (HP) structure will affect the other healthy side of the hippocampal network is still unclear. Here, we used a seed-based method to explore the commonly alterative hippocampal network in mTLE patients by comparing the bilateral hippocampal network of unilateral mTLE patients with healthy control participants. We observed that both sides of the hippocampal network in unilateral mTLE patients were changed independent of the affected or "healthy" side, which may suggest a common plasticity network for both sides of hippocampal sclerosis mesial temporal lobe epilepsy patients. Furthermore, using the HP as the ROI, we found that the functional connectivity of the intra-HP in the left mTLE-HS group was moderately positively correlated with the duration of the disease, while a strong negative correlation between functional connectivity of the intra-HP and duration were detected in the right mTLE-HS group, which suggested that it was easier for the right HP than the left HP to communicate with the contralateral HP according to the progression of mTLE disease because the hippocampus plays different roles in the communication and compensatory mechanism associated with the contralateral side of the hemisphere. We hope that this potential relevance may help us to better characterize mTLE with hippocampal sclerosis and ultimately assist in providing a better diagnosis and more accurate invasive treatments of mTLE.
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Affiliation(s)
- Hong Li
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Wenliang Fan
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Jie Yang
- Department of Communication Sciences and Disorders, Massachusetts General Hospital Institute of Health Professions, Boston, MA, USA.
| | - Shuyan Song
- School of Life Science and Technology, Key Laboratory of Image Processing and Intelligent Control of Education Ministry of China, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Yuan Liu
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Ping Lei
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Lochan Shrestha
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Grace Mella
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Wei Chen
- Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China; Radiology and Medical Imaging Center, The First People's Hospital of Yibin, Sichuan 644000, China.
| | - Haibo Xu
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
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Chiang S, Stern JM, Engel J, Haneef Z. Structural-functional coupling changes in temporal lobe epilepsy. Brain Res 2015; 1616:45-57. [PMID: 25960346 DOI: 10.1016/j.brainres.2015.04.052] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/24/2015] [Accepted: 04/28/2015] [Indexed: 12/13/2022]
Abstract
Alterations in both structural connectivity (SC) and functional connectivity (FC) have been reported in temporal lobe epilepsy (TLE). However, the relationship between FC and SC remains less understood. This study used functional connectivity MRI and diffusion tensor imaging to examine coupling of FC and SC within the limbic network of TLE, as well as its relation to epilepsy duration, regional changes, and disease laterality in 14 patients with left TLE, 10 with right TLE, and 11 healthy controls. Structural and functional networks were separately constructed and the correlation estimated between structural and functional connectivity. This measure of SC-FC coupling was compared between left/right TLE and controls, and correlated with epilepsy duration. Elastic net regression was used to investigate regional structural and functional changes associated with SC-FC coupling. SC-FC coupling was decreased in left TLE compared to controls, and accompanied by reductions in FC for left and right TLE and in SC for left TLE. When examined in relation to disease duration, an increase in SC-FC coupling with longer epilepsy duration was observed, associated predominantly with structural loss of the fusiform and frontal inferior orbital gyrus in left TLE and functional hub redistribution in right TLE. These results suggest that decoupling between structural and functional networks in TLE is modulated by several factors, including epilepsy duration and regional changes in the fusiform, frontal inferior orbital gyrus, posterior cingulate, and hippocampus. SC-FC coupling may provide a more sensitive biomarker of disease burden in TLE than biomarkers based on single imaging modalities.
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Affiliation(s)
- Sharon Chiang
- Department of Statistics, Rice University, Houston, TX, USA
| | - John M Stern
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - Jerome Engel
- Department of Neurology, University of California, Los Angeles, CA, USA; Department of Neurobiology, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; The Brain Research Institute, University of California, Los Angeles, CA, USA
| | - Zulfi Haneef
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Neurology Care Line, VA Medical Center, Houston, TX, USA.
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22
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Coito A, Plomp G, Genetti M, Abela E, Wiest R, Seeck M, Michel CM, Vulliemoz S. Dynamic directed interictal connectivity in left and right temporal lobe epilepsy. Epilepsia 2015; 56:207-17. [PMID: 25599821 DOI: 10.1111/epi.12904] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVE There is increasing evidence that epileptic activity involves widespread brain networks rather than single sources and that these networks contribute to interictal brain dysfunction. We investigated the fast-varying behavior of epileptic networks during interictal spikes in right and left temporal lobe epilepsy (RTLE and LTLE) at a whole-brain scale using directed connectivity. METHODS In 16 patients, 8 with LTLE and 8 with RTLE, we estimated the electrical source activity in 82 cortical regions of interest (ROIs) using high-density electroencephalography (EEG), individual head models, and a distributed linear inverse solution. A multivariate, time-varying, and frequency-resolved Granger-causal modeling (weighted Partial Directed Coherence) was applied to the source signal of all ROIs. A nonparametric statistical test assessed differences between spike and baseline epochs. Connectivity results between RTLE and LTLE were compared between RTLE and LTLE and with neuropsychological impairments. RESULTS Ipsilateral anterior temporal structures were identified as key drivers for both groups, concordant with the epileptogenic zone estimated invasively. We observed an increase in outflow from the key driver already before the spike. There were also important temporal and extratemporal ipsilateral drivers in both conditions, and contralateral only in RTLE. A different network pattern between LTLE and RTLE was found: in RTLE there was a much more prominent ipsilateral to contralateral pattern than in LTLE. Half of the RTLE patients but none of the LTLE patients had neuropsychological deficits consistent with contralateral temporal lobe dysfunction, suggesting a relationship between connectivity changes and cognitive deficits. SIGNIFICANCE The different patterns of time-varying connectivity in LTLE and RTLE suggest that they are not symmetrical entities, in line with our neuropsychological results. The highest outflow region was concordant with invasive validation of the epileptogenic zone. This enhanced characterization of dynamic connectivity patterns could better explain cognitive deficits and help the management of epilepsy surgery candidates.
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Affiliation(s)
- Ana Coito
- Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland
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Malikova H, Kramska L, Vojtech Z, Sroubek J, Lukavsky J, Liscak R. Relationship between remnant hippocampus and amygdala and memory outcomes after stereotactic surgery for mesial temporal lobe epilepsy. Neuropsychiatr Dis Treat 2015; 11:2927-33. [PMID: 26640379 PMCID: PMC4657808 DOI: 10.2147/ndt.s95497] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Mesial temporal structures play an important role in human memory. In mesial temporal lobe epilepsy (MTLE), seizure activity is generated from the same structures. Surgery is the definitive treatment for medically intractable MTLE. In addition to standard temporal lobe microsurgical resection, stereotactic radiofrequency amygdalohippocampectomy (SAHE) is used as an alternative MTLE treatment. While memory impairments after standard epilepsy surgery are well known, it has been shown that memory decline is not a feature of SAHE. The aim of the present study was to correlate the volume of the remnant hippocampus and amygdala in patients treated by SAHE with changes in memory parameters. MATERIALS AND METHODS Thirty-seven MTLE patients treated by SAHE (ten right, 27 left) were included. Patients underwent magnetic resonance imaging examinations including hippocampal and amygdalar volumetry and neuropsychological evaluation preoperatively and 1 year after surgery. RESULTS Using Spearman correlation analyses, larger left-sided hippocampal reductions were associated with lower verbal memory performance (ρ=-0.46; P=0.02). On the contrary, improvement of global memory quotient (MQ) was positively correlated with larger right-sided hippocampal reduction (ρ=0.66; P=0.04). Similarly, positive correlations between the extent of right amygdalar reduction and verbal MQ (ρ=0.74; P=0.02) and global MQ change (ρ=0.69; P=0.03) were found. Thus, larger right hippocampal and amygdalar reduction was associated with higher global and verbal MQ change after SAHE. CONCLUSION Larger left-sided hippocampal reductions were associated with lower verbal memory performance. This finding is in accordance with the material-specific model of human memory, which states that the dominant hemisphere is specialized for the learning and recall of verbal information. We hypothesize that larger right-sided ablations enable the left temporal lobe to support memory more effectively, perhaps as a consequence of epileptiform discharges spreading from remnants of right mesiotemporal structures to the left.
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Affiliation(s)
- Hana Malikova
- Department of Radiology, Na Homolce Hospital, Prague, Czech Republic ; Institute of Anatomy, Second Medical Faculty, Charles University in Prague, Prague, Czech Republic
| | - Lenka Kramska
- Department of Clinical Psychology, Na Homolce Hospital, Prague, Czech Republic
| | - Zdenek Vojtech
- Department of Neurology, Na Homolce Hospital, Prague, Czech Republic ; Department of Neurology, 3rd Medical Faculty, Charles University in Prague, Prague, Czech Republic
| | - Jan Sroubek
- Department of Neurosurgery, Na Homolce Hospital, Prague, Czech Republic
| | - Jiri Lukavsky
- Institute of Psychology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Roman Liscak
- Department of Radiation and Stereotactic Neurosurgery, Na Homolce Hospital, Prague, Czech Republic
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Chiang S, Stern JM, Engel J Jr, Levin HS, Haneef Z. Differences in graph theory functional connectivity in left and right temporal lobe epilepsy. Epilepsy Res 2014; 108:1770-81. [PMID: 25445238 DOI: 10.1016/j.eplepsyres.2014.09.023] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/07/2014] [Accepted: 09/20/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate lateralized differences in limbic system functional connectivity between left and right temporal lobe epilepsy (TLE) using graph theory. METHODS Interictal resting state fMRI was performed in 14 left TLE patients, 11 right TLE patients, and 12 controls. Graph theory analysis of 10 bilateral limbic regions of interest was conducted. Changes in edgewise functional connectivity, network topology, and regional topology were quantified, and then left and right TLE were compared. RESULTS Limbic edgewise functional connectivity was predominantly reduced in both left and right TLE. More regional connections were reduced in right TLE, most prominently involving reduced interhemispheric connectivity between the bilateral insula and bilateral hippocampi. A smaller number of limbic connections were increased in TLE, more so in left than in right TLE. Topologically, the most pronounced change was a reduction in average network betweenness centrality and concurrent increase in left hippocampal betweenness centrality in right TLE. In contrast, left TLE exhibited a weak trend toward increased right hippocampal betweenness centrality, with no change in average network betweenness centrality. CONCLUSION Limbic functional connectivity is predominantly reduced in both left and right TLE, with more pronounced reductions in right TLE. In contrast, left TLE exhibits both edgewise and topological changes that suggest a tendency toward reorganization. Network changes in TLE and lateralized differences thereof may have important diagnostic and prognostic implications.
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Haneef Z, Lenartowicz A, Yeh HJ, Engel J, Stern JM. Network analysis of the default mode network using functional connectivity MRI in Temporal Lobe Epilepsy. J Vis Exp 2014:e51442. [PMID: 25146174 DOI: 10.3791/51442] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Functional connectivity MRI (fcMRI) is an fMRI method that examines the connectivity of different brain areas based on the correlation of BOLD signal fluctuations over time. Temporal Lobe Epilepsy (TLE) is the most common type of adult epilepsy and involves multiple brain networks. The default mode network (DMN) is involved in conscious, resting state cognition and is thought to be affected in TLE where seizures cause impairment of consciousness. The DMN in epilepsy was examined using seed based fcMRI. The anterior and posterior hubs of the DMN were used as seeds in this analysis. The results show a disconnection between the anterior and posterior hubs of the DMN in TLE during the basal state. In addition, increased DMN connectivity to other brain regions in left TLE along with decreased connectivity in right TLE is revealed. The analysis demonstrates how seed-based fcMRI can be used to probe cerebral networks in brain disorders such as TLE.
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Affiliation(s)
- Zulfi Haneef
- Department of Neurology, Baylor College of Medicine; Neurology Care Line, Michael E. DeBakey VA Medical Center;
| | - Agatha Lenartowicz
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles
| | - Hsiang J Yeh
- Department of Neurology, University of California, Los Angeles
| | - Jerome Engel
- Department of Neurology, University of California, Los Angeles
| | - John M Stern
- Department of Neurology, University of California, Los Angeles
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Haneef Z, Chen DK. Functional neuro-imaging as a pre-surgical tool in epilepsy. Ann Indian Acad Neurol 2014; 17:S56-64. [PMID: 24791091 PMCID: PMC4001213 DOI: 10.4103/0972-2327.128659] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 09/20/2013] [Accepted: 10/02/2013] [Indexed: 12/03/2022] Open
Abstract
Functional neuro-imaging techniques are helpful in the pre-surgical evaluation of epilepsy for localization of the epileptogenic zone as ancillary tools to electroencephalography (EEG) and magnetic resonance imaging (MRI) or when other localization techniques are normal, non-concordant or discordant. Positron emission tomography (PET) and ictal single photon emission computed tomography (ictal SPECT) imaging are traditional tests that have been reported to have good sensitivity and specificity although the results are better with more expertise as is true for any technique. More recently magnetoencephalogram/magnetic source imaging (MEG/MSI), diffusion tensor imaging and functional magnetic resonance imaging (fMRI) have been used in localization and functional mapping during the pre-surgical work-up of epilepsy. Newer techniques such as fMRI-EEG, functional connectivity magnetic resonance imaging and near infra-red spectroscopy, magnetic resonance spectroscopy and magneto nanoparticles hold promise for further development that could then be applied in the work-up of epilepsy surgery. In this manuscript, we review these techniques and their current position in the pre-surgical evaluation of epilepsy.
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Affiliation(s)
- Zulfi Haneef
- Kellaway Section of Neurophysiology, Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
- Kellaway Section of Neurophysiology, Neurology Care Line, Michael E. DeBakey VA Medical Center, Houston, Texas, USA
| | - David K. Chen
- Kellaway Section of Neurophysiology, Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
- Kellaway Section of Neurophysiology, Neurology Care Line, Michael E. DeBakey VA Medical Center, Houston, Texas, USA
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Sidhu MK, Stretton J, Winston GP, Bonelli S, Centeno M, Vollmar C, Symms M, Thompson PJ, Koepp MJ, Duncan JS. A functional magnetic resonance imaging study mapping the episodic memory encoding network in temporal lobe epilepsy. ACTA ACUST UNITED AC 2013; 136:1868-88. [PMID: 23674488 PMCID: PMC3673458 DOI: 10.1093/brain/awt099] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Functional magnetic resonance imaging has demonstrated reorganization of memory encoding networks within the temporal lobe in temporal lobe epilepsy, but little is known of the extra-temporal networks in these patients. We investigated the temporal and extra-temporal reorganization of memory encoding networks in refractory temporal lobe epilepsy and the neural correlates of successful subsequent memory formation. We studied 44 patients with unilateral temporal lobe epilepsy and hippocampal sclerosis (24 left) and 26 healthy control subjects. All participants performed a functional magnetic resonance imaging memory encoding paradigm of faces and words with subsequent out-of-scanner recognition assessments. A blocked analysis was used to investigate activations during encoding and neural correlates of subsequent memory were investigated using an event-related analysis. Event-related activations were then correlated with out-of-scanner verbal and visual memory scores. During word encoding, control subjects activated the left prefrontal cortex and left hippocampus whereas patients with left hippocampal sclerosis showed significant additional right temporal and extra-temporal activations. Control subjects displayed subsequent verbal memory effects within left parahippocampal gyrus, left orbitofrontal cortex and fusiform gyrus whereas patients with left hippocampal sclerosis activated only right posterior hippocampus, parahippocampus and fusiform gyrus. Correlational analysis showed that patients with left hippocampal sclerosis with better verbal memory additionally activated left orbitofrontal cortex, anterior cingulate cortex and left posterior hippocampus. During face encoding, control subjects showed right lateralized prefrontal cortex and bilateral hippocampal activations. Patients with right hippocampal sclerosis showed increased temporal activations within the superior temporal gyri bilaterally and no increased extra-temporal areas of activation compared with control subjects. Control subjects showed subsequent visual memory effects within right amygdala, hippocampus, fusiform gyrus and orbitofrontal cortex. Patients with right hippocampal sclerosis showed subsequent visual memory effects within right posterior hippocampus, parahippocampal and fusiform gyri, and predominantly left hemisphere extra-temporal activations within the insula and orbitofrontal cortex. Correlational analysis showed that patients with right hippocampal sclerosis with better visual memory activated the amygdala bilaterally, right anterior parahippocampal gyrus and left insula. Right sided extra-temporal areas of reorganization observed in patients with left hippocampal sclerosis during word encoding and bilateral lateral temporal reorganization in patients with right hippocampal sclerosis during face encoding were not associated with subsequent memory formation. Reorganization within the medial temporal lobe, however, is an efficient process. The orbitofrontal cortex is critical to subsequent memory formation in control subjects and patients. Activations within anterior cingulum and insula correlated with better verbal and visual subsequent memory in patients with left and right hippocampal sclerosis, respectively, representing effective extra-temporal recruitment.
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Affiliation(s)
- Meneka K Sidhu
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Vonck K, Sprengers M, Carrette E, Dauwe I, Miatton M, Meurs A, Goossens L, DE Herdt V, Achten R, Thiery E, Raedt R, VAN Roost D, Boon P. A decade of experience with deep brain stimulation for patients with refractory medial temporal lobe epilepsy. Int J Neural Syst 2012; 23:1250034. [PMID: 23273130 DOI: 10.1142/s0129065712500347] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study, we present long-term results from patients with medial temporal lobe (MTL) epilepsy treated with deep brain stimulation (DBS). Since 2001, 11 patients (8M) with refractory MTL epilepsy underwent MTL DBS. When unilateral DBS failed to decrease seizures by > 90%, a switch to bilateral MTL DBS was proposed. After a mean follow-up of 8.5 years (range: 67-120 months), 6/11 patients had a ≥ 90% seizure frequency reduction with 3/6 seizure-free for > 3 years; three patients had a 40%-70% reduction and two had a < 30% reduction. In 3/5 patients switching to bilateral DBS further improved outcome. Uni- or bilateral MTL DBS did not affect neuropsychological functioning. This open study with an extended long-term follow-up demonstrates maintained efficacy of DBS for MTL epilepsy. In more than half of the patients, a seizure frequency reduction of at least 90% was reached. Bilateral MTL DBS may herald superior efficacy in unilateral MTL epilepsy.
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Affiliation(s)
- Kristl Vonck
- Department of Neurology, Reference Center for Refractory Epilepsy, Gent, Belgium.
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Haneef Z, Lenartowicz A, Yeh HJ, Engel J, Stern JM. Effect of lateralized temporal lobe epilepsy on the default mode network. Epilepsy Behav 2012; 25:350-7. [PMID: 23103309 PMCID: PMC4209897 DOI: 10.1016/j.yebeh.2012.07.019] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/20/2012] [Accepted: 07/23/2012] [Indexed: 11/28/2022]
Abstract
The default mode network (DMN) is composed of cerebral regions involved in conscious, resting state cognition. The hippocampus is an essential component of this network. Here, the DMN in TLE is compared to control subjects to better understand its involvement in TLE. We performed resting state connectivity analysis using regions of interest (ROIs) in the retrosplenium/precuneus (Rsp/PCUN) and the ventro-medial pre-frontal cortex (vmPFC) in 36 subjects (11 with right TLE, 12 with left TLE, 13 controls) to delineate the posterior and anterior DMN regions respectively. We found reduced connectivity of the posterior to the anterior DMN in patients with both right and left TLE. However, the posterior and anterior networks were found to be individually preserved. Lateralization of TLE affects the DMN with left TLE demonstrating more extensive networks. These DMN changes may be relevant to altered cognition and memory in TLE and may be relevant to right vs. left TLE differences in cognitive involvement.
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Affiliation(s)
- Zulfi Haneef
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Agatha Lenartowicz
- Department of Psychology, University of California, Los Angeles, CA, USA
| | - Hsiang J. Yeh
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - Jerome Engel
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - John M. Stern
- Department of Neurology, University of California, Los Angeles, CA, USA
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Szaflarski JP, Allendorfer JB. Topiramate and its effect on fMRI of language in patients with right or left temporal lobe epilepsy. Epilepsy Behav 2012; 24:74-80. [PMID: 22481042 PMCID: PMC3564045 DOI: 10.1016/j.yebeh.2012.02.022] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 11/15/2022]
Abstract
Topiramate (TPM) is well recognized for its negative effects on cognition, language performance and lateralization results on the intracarotid amobarbital procedure (IAP). But, the effects of TPM on functional MRI (fMRI) of language and the fMRI signals are less clear. Functional MRI is increasingly used for presurgical evaluation of epilepsy patients in place of IAP for language lateralization. Thus, the goal of this study was to assess the effects of TPM on fMRI signals. In this study, we included 8 patients with right temporal lobe epilepsy (RTLE) and 8 with left temporal lobe epilepsy (LTLE) taking TPM (+TPM). Matched to them for age, handedness and side of seizure onset were 8 patients with RTLE and 8 with LTLE not taking TPM (-TPM). Matched for age and handedness to the patients with TLE were 32 healthy controls. The fMRI paradigm involved semantic decision/tone decision task (in-scanner behavioral data were collected). All epilepsy patients received a standard neuropsychological language battery. One sample t-tests were performed within each group to assess task-specific activations. Functional MRI data random-effects analysis was performed to determine significant group activation differences and to assess the effect of TPM dose on task activation. Direct group comparisons of fMRI, language and demographic data between patients with R/L TLE +TPM vs. -TPM and the analysis of the effects of TPM on blood oxygenation level-dependent (BOLD) signal were performed. Groups were matched for age, handedness and, within the R/L TLE groups, for the age of epilepsy onset/duration and the number of AEDs/TPM dose. The in-scanner language performance of patients was worse when compared to healthy controls - all p<0.044. While all groups showed fMRI activation typical for this task, regression analyses comparing L/R TLE +TPM vs. -TPM showed significant fMRI signal differences between groups (increases in left cingulate gyrus and decreases in left superior temporal gyrus in the patients with LTLE +TPM; increases in the right BA 10 and left visual cortex and decreases in the left BA 47 in +TPM RTLE). Further, TPM dose showed positive relationship with activation in the basal ganglia and negative associations with activation in anterior cingulate and posterior visual cortex. Thus, TPM appears to have a different effect on fMRI language distribution in patients with R/L TLE and a dose-dependent effect on fMRI signals. These findings may, in part, explain the negative effects of TPM on cognition and language performance and support the notion that TPM may affect the results of language fMRI lateralization/localization.
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Affiliation(s)
- Jerzy P. Szaflarski
- Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA,Cincinnati Epilepsy Center at the University Hospital in Cincinnati, University of Cincinnati Academic Health Center, Cincinnati, OH, USA,Corresponding author at: University of Cincinnati Academic Health Center, Department of Neurology, 260 Stetson Street, Cincinnati, OH 45267-0525, USA. (J.P. Szaflarski)
| | - Jane B. Allendorfer
- Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA
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Vlooswijk MCG, Jansen JFA, Jeukens CRLPN, Majoie HJM, Hofman PAM, de Krom MCTFM, Aldenkamp AP, Backes WH. Memory processes and prefrontal network dysfunction in cryptogenic epilepsy. Epilepsia 2011; 52:1467-75. [PMID: 21635235 DOI: 10.1111/j.1528-1167.2011.03108.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Impaired memory performance is the most frequently reported cognitive problem in patients with chronic epilepsy. To examine memory deficits many studies have focused on the role of the mesiotemporal lobe, mostly with hippocampal abnormalities. However, the role of the prefrontal brain remains unresolved. To investigate the neuronal correlates of working memory dysfunction in patients without structural lesions, a combined study of neurocognitive assessment, hippocampal and cerebral volumetry, and functional magnetic resonance imaging of temporal and frontal memory networks was performed. METHODS Thirty-six patients with cryptogenic localization-related epilepsy and 21 healthy controls underwent neuropsychological assessment of intelligence (IQ) and memory. On T(1) -weighted images obtained by 3-Tesla magnetic resonance imaging (MRI), volumetry of the hippocampi and the cerebrum was performed. Functional MRI (fMRI) was performed with a novel picture encoding and Sternberg paradigm that activated different memory-mediating brain regions. Functional connectivity analysis comprised cross-correlation of signal time-series of the most strongly activated regions involved in working memory function. KEY FINDINGS Patients with epilepsy displayed lower IQ values; impaired transient aspects of information processing, as indicated by lower scores on the digit-symbol substitution test (DSST); and decreased short-term memory performance relative to healthy controls, as measured with the Wechsler Adult Intelligence Scale subtests for working memory, and word and figure recognition. This could not be related to any hippocampal volume changes. No group differences were found regarding volumetry or fMRI-derived functional activation. In the Sternberg paradigm, a network involving the anterior cingulate and the middle and inferior frontal gyrus was activated. A reduced strength of four connections in this prefrontal network was associated with the DSST and word recognition performance in the patient group. SIGNIFICANCE Deficits in the processes involved in transient working memory, and to a lesser extent in short-term memory, in patients with localization-related epilepsy of both temporal and extratemporal origin cannot be attributed to hippocampal atrophy or function only, but are also related to reduced functional connectivity in the prefrontal brain. Because patients with symptomatic lesions or mesiotemporal sclerosis were excluded from this study, the results cannot be explained by structural lesions. Therefore, the current findings highlight the influence of epilepsy on the prefrontal network integrity as a possible underlying problem of memory impairment.
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Affiliation(s)
- Marielle C G Vlooswijk
- Department of Neurology, Maastricht University Medical Centre, Maastricht, The Netherlands.
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Guedj E, Bettus G, Barbeau EJ, Liégeois-Chauvel C, Confort-Gouny S, Bartolomei F, Chauvel P, Cozzone PJ, Ranjeva JP, Guye M. Hyperactivation of parahippocampal region and fusiform gyrus associated with successful encoding in medial temporal lobe epilepsy. Epilepsia 2011; 52:1100-9. [PMID: 21480879 DOI: 10.1111/j.1528-1167.2011.03052.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Performance in recognition memory differs among patients with medial temporal lobe epilepsy (MTLE). We aimed to determine if distinct recognition performances (normal vs. impaired) could be related to distinct patterns of brain activation during encoding. METHODS Event-related functional magnetic resonance imaging (fMRI) activation profiles were obtained during successful encoding of non-material-specific items, in 14 MTLE patients tested for recognition of stimuli afterward. Findings were compared to those of 25 healthy subjects, and voxel-based correlations were assessed between brain activation and performance. KEY FINDINGS Patients with left and right MTLE showed similar activations and similar performances. As a whole, the group of patients demonstrated altered recognition scores, but three of the seven patients with left MTLE and three of the seven patients with right MTLE exhibited normal performance relative to controls. In comparison to healthy subjects and patients with impaired recognition, patients with normal recognition showed weaker activations in left opercular cortex, but stronger activations in bilateral parahippocampal region/fusiform gyrus (PH/FG). By contrast, patients with impaired performance showed weaker activations in bilateral PH/FG, but stronger activations in a frontal/cingulate and parietal network. Recognition performance was correlated positively to bilateral PH/FG activations, and negatively correlated to bilateral frontal/cingulate activations, in the whole group of patients, as well as in subgroups of patients with either left or right MTLE. SIGNIFICANCE These results suggest occurrence of effective functional compensation within bilateral PH/FG in MTLE, allowing patients to maintain recognition capability. In contrast, impairment of this perceptive-memory system may lead to alternative activation of an inefficient nonspecific attentional network in patients with altered performance.
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Affiliation(s)
- Eric Guedj
- Center for Magnetic Resonance in Biomedicine (CRMBM), UMR CNRS 6612, Marseille, France
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Abstract
Medial temporal lobe epilepsy is a chronic neurological disease that begins in the early age and that is associated with frequent and disturbing memory deficits. Repeated seizures will lead to the formation of an epileptogenic network that may interfere with physiological neuronal networks and thus with normal brain function: by direct activation or indirectly by deactivation during a seizure, see for example the dreamy state or the ''déja vécu'' phenomenon during temporal seizures; by ictal or post-ictal inhibition, see for example ictal or post-ictal amnesia; by a repetitive and chronic modulation leading to a reorganization of the physiological neuronal networks. The study of these interactions between epileptic and physiological neural networks must lead to better explore the patient's memory and predict memory worsening before temporal lobe surgery and to better understand the reorganization of memory networks in chronic epilepsy. The goal is double: (1) improve the prediction of post-operative memory worsening and guide rehabilitation in epileptic clinical practice; (2) improve the pathophysiological knowledge about memory processes.
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Vlooswijk MC, Jansen JF, de Krom MC, Majoie HM, Hofman PA, Backes WH, Aldenkamp AP. Functional MRI in chronic epilepsy: associations with cognitive impairment. Lancet Neurol 2010; 9:1018-27. [PMID: 20708970 DOI: 10.1016/s1474-4422(10)70180-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic epilepsy is frequently accompanied by serious cognitive side-effects. Clinical factors are important, but cannot account entirely for this cognitive comorbidity. Therefore, research is focusing on the underlying cerebral mechanisms to understand the development of cognitive dysfunction. In the past two decades, functional MRI techniques have been applied extensively to the study of cognitive impairment in chronic epilepsy. However, because of wide variation in study designs, analysis methods, and data presentation, interpretation of these studies has become increasingly difficult for clinicians. In patients with localisation-related epilepsy, whether findings of functional MRI represent the underlying neuronal substrate for cognitive decline remains a subject of debate.
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Affiliation(s)
- Marielle Cg Vlooswijk
- Department of Neurology, Maastricht University Medical Centre, Maastricht, Netherlands
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Zhang Z, Lu G, Zhong Y, Tan Q, Liao W, Wang Z, Wang Z, Li K, Chen H, Liu Y. Altered spontaneous neuronal activity of the default-mode network in mesial temporal lobe epilepsy. Brain Res 2010; 1323:152-60. [DOI: 10.1016/j.brainres.2010.01.042] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/14/2010] [Accepted: 01/15/2010] [Indexed: 11/25/2022]
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Akanuma N, Reed LJ, Marsden PK, Jarosz J, Adachi N, Hallett WA, Alarcón G, Morris RG, Koutroumanidis M. Hemisphere-specific Episodic Memory Networks in the Human Brain: A Correlation Study between Intracarotid Amobarbital Test and [18F]FDG-PET. J Cogn Neurosci 2009; 21:605-22. [DOI: 10.1162/jocn.2009.21035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
The purpose of the present study was to explore the brain regions involved in human episodic memory by correlating unilateral memory performance estimated by the intracarotid amobarbital test (IAT) and interictal cerebral metabolism measured by [18F]fluorodeoxyglucose positron emission tomography ([18F]FDG-PET). Using this method, regional alterations of cerebral metabolism associated with epilepsy pathophysiology are used to predict hemisphere-specific episodic memory function, hence, investigate the differential distribution of memory in each hemisphere. Sixty-two patients with unilateral temporal lobe epilepsy (35 left and 27 right) were studied using [18F]FDG-PET with complementary voxel-based statistical parametric mapping (SPM) and region-of-interest (ROI) methods of analysis. Positive regression was analyzed in SPM with a series of different thresholds (p = .001, .01 or .05) with a correction to 100 voxels. IAT memory performance in which left hemisphere was tested by right-sided injection of amobarbital correlated with [18F]FDG uptake in left lateral and medial temporal regions, and in the left ventrolateral frontal cortex. Right IAT memory performance correlated with [18F]FDG uptake in the right inferior parietal lobule, right dorsolateral frontal cortex, right precentral gyrus, and caudal portion of the right anterior cingulate cortex. ROI analysis corroborated these results. Analyses carried out separately in patients with left (n = 50) and nonleft (n = 12) dominance for language showed that in the nonleft dominant group, right IAT scores correlated with right fronto-temporal regions, whereas left total memory scores correlated with left lateral and medial temporal regions. The findings indicate that (i) episodic memory is subserved by more widespread cortical regions beyond the core mesiotemporal lobe memory structures; (ii) there are different networks functional in the two hemispheres; and (iii) areas involved in memory may be different between patients with left and nonleft dominance for language, particularly in the right hemisphere.
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Affiliation(s)
- Nozomi Akanuma
- 1South London & Maudsley NHS Foundation Trust, London, UK
- 2St Thomas' Hospital
- 3King's College London, UK
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Eliassen JC, Holland SK, Szaflarski JP. Compensatory brain activation for recognition memory in patients with medication-resistant epilepsy. Epilepsy Behav 2008; 13:463-9. [PMID: 18611446 PMCID: PMC2609901 DOI: 10.1016/j.yebeh.2008.06.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2008] [Revised: 06/18/2008] [Accepted: 06/19/2008] [Indexed: 11/19/2022]
Abstract
Progressive decline of memory functions has been observed in patients with chronic medication-resistant epilepsy. The progression likely relates to the effects of epileptiform discharges, seizures, and medications on the processes of encoding and retrieval. The goal of the study described here was to use functional MRI (fMRI) to examine the effects of chronic epilepsy on verbal recognition memory. We enrolled 12 patients with medication-resistant epilepsy (5 with right and 7 with left hemispheric seizure onset) and 18 healthy controls matched for age, gender, and handedness. Subjects underwent fMRI at 3T using a word recognition task during which they had to recall if words presented during scanning were words they had learned prior to scanning. Although we noted many similarities in the fMRI activation patterns between the subjects with epilepsy and the healthy subjects in areas typically involved in memory processing, testing of the interaction effects for target-foil differences between groups revealed several differences in activation including the right insula, the left cuneus, and the bilateral subgenual anterior cingulate cortex (ACC). In patients with epilepsy, these regions exhibited greater activation for targets than foils, but in healthy subjects the difference was reversed (right insula), absent (left cuneus), or included deactivation to target words (pregenual ACC). These differences were seen despite similar performance during the memory task, suggesting that activations observed in these additional regions may represent compensatory processes for verbal recognition memory that are induced by chronic brain injury related to recurrent seizures.
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Affiliation(s)
- James C. Eliassen
- Center for Imaging Research, Cincinnati Epilepsy Center, University of Cincinnati Academic Health Center, Cincinnati, OH
- Department of Psychiatry, Cincinnati Epilepsy Center, University of Cincinnati Academic Health Center, Cincinnati, OH
| | - Scott K. Holland
- Imaging Research Center and Department of Radiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Jerzy P. Szaflarski
- Center for Imaging Research, Cincinnati Epilepsy Center, University of Cincinnati Academic Health Center, Cincinnati, OH
- Department of Neurology, Cincinnati Epilepsy Center, University of Cincinnati Academic Health Center, Cincinnati, OH
- The Neuroscience Institute, Cincinnati, OH, USA
- Address for correspondence: Jerzy P. Szaflarski, MD, PhD; University of Cincinnati Academic Health Center; Department of Neurology; 260 Stetson Street, Rm. 2350; ML 0525; Cincinnati, OH 45267-0525; E-mail: ; Phone: 513.558.4050
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Abstract
Structural and functional neuroimaging continues to play an increasing role in the presurgical evaluation of patients with epilepsy. In addition to its value in localizing the epileptogenic zone and eloquent cortex, neuroimaging is contributing to our understanding of mood comorbidity in epilepsy. Although the vast majority of research has focused on patients with temporal lobe epilepsy (TLE), neuroimaging studies of patients with extratemporal epilepsy and primary generalized epilepsy are increasing in number. In this review, structural and functional imaging modalities that have received considerable research attention in recent years are reviewed, and their strengths and limitations for understanding behavior in epilepsy are assessed. In addition, advances in multimodal imaging are discussed along with their potential application to the presurgical evaluation of patients with seizure disorders.
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Affiliation(s)
- Carrie R. McDonald
- Department of Psychiatry, University of California, San Diego, Multimodal Imaging Laboratory, University of California, San Diego
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Abstract
The field of epilepsy has contributed significantly to localization of neurologic function, particularly in the neocortex. Methodologies such as cortical stimulation, positron emission tomography, functional MRI, trans-cranial magnetic stimulation, surgical resection, and magnetoencephalography have been used successfully in patients with epilepsy to locate specific functions, primarily for the purpose of defining eloquent cortex before surgical resections. The left hemisphere serves language-related functions and verbal memory in most people, whereas the right hemisphere serves some language function in addition to perceiving most components of music and other forms of nonverbal material. Both hemispheres cooperate in understanding spatial relationships. Studies in patients with developmental abnormalities have enriched our understanding of localization of function within the cortex. Future studies may help us understand the sequence in which specific regions are activated during specific tasks and determine which regions are necessary for tasks and which are supplementary. The ability to predict preoperatively the effect of removal of specific tissues would benefit surgical planning for all patients who undergo cortical resections, including those with epilepsy.
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Foster PS, Harrison DW, Crucian GP, Drago V, Rhodes RD, Heilman KM. Reduced Verbal Learning Associated With Posterior Temporal Lobe Slow Wave Activity. Dev Neuropsychol 2007; 33:25-43. [DOI: 10.1080/87565640701729706] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lehmann S, Morand S, James C, Schnider A. Electrophysiological correlates of deficient encoding in a case of post-anoxic amnesia. Neuropsychologia 2007; 45:1757-66. [PMID: 17291548 DOI: 10.1016/j.neuropsychologia.2006.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 12/19/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Abstract
Little is known about the initial stages of information processing in amnesia as compared to normal memory. In this study, we used electrical spatiotemporal mapping to compare cortical activation during encoding and recognition in a 56-year-old patient with severe, chronic post-anoxic amnesia and an age-matched control group. Event-related potentials were recorded as the subjects performed a continuous recognition task composed of meaningful designs. Activation in the control group rapidly progressed through eight different electrocortical configurations over 700 ms after onset of new stimuli. In contrast, activation in the amnesic patient was highly monotonous: it showed varying electrocortical patterns only during the first 150 ms but then remained abnormally stable for the remainder of the analysed time window. Electrical source localisation revealed that the patient failed to activate distributed cortical networks and that his processing was confined to visual areas. The present study suggests that the rapid activation of distributed cortical networks is critical for efficient encoding.
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Affiliation(s)
- Sandra Lehmann
- Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital, CH-1211 Geneva 14, Switzerland
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Abstract
PURPOSE To examine the effects of illness duration on the neural processing of memory in patients with temporal lobe epilepsy (TLE) by using functional MRI. METHODS Twenty-three TLE patients (16 left, seven right) performed a complex visual scene-encoding task during functional MRI. Region-of-interest (ROI) analyses were used to quantity functional activation in the mesial temporal and frontal lobes. The patients' verbal and visual memory performances were evaluated by standardized neuropsychological tests. Analyses included group comparison and correlations of duration of epilepsy with functional activation and memory performance. RESULTS Compared with normal controls, TLE patients demonstrated reduced activation bilaterally in the mesial temporal lobe (p=0.003), and the reduction was more pronounced on the ipsilateral side of the seizure focus. Moreover, a longer duration of illness was associated with fewer voxels activated in both the left (p=0.038) and right (p=0.017) mesial temporal lobe. Furthermore, the duration of illness was found to be significantly and negatively correlated with both verbal (p=0.020) and visual (p=0.000) memory functioning. CONCLUSIONS TLE seems to affect the memory processes in the mesial temporal lobes progressively (i.e., the longer the duration of illness, the lower the brain activation). In turn, the reduction of brain activation negatively affects memory functioning. Finally, the reduction is not limited to the side of seizure but also is observed in the contralateral hemisphere.
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Affiliation(s)
- Mei-chun Cheung
- Department of Psychology, The Chinese University of Hong Kong, Hong Kong SAR
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43
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Araújo D, Santos AC, Velasco TR, Wichert-Ana L, Terra-Bustamante VC, Alexandre V, Carlotti CG, Assirati JA, Machado HR, Walz R, Leite JP, Sakamoto AC. Volumetric Evidence of Bilateral Damage in Unilateral Mesial Temporal Lobe Epilepsy. Epilepsia 2006; 47:1354-9. [PMID: 16922881 DOI: 10.1111/j.1528-1167.2006.00605.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE We sought to analyze the contralateral volumes of the temporal pole, posterior segment of the temporal lobe, amygdala, hippocampus, and parahippocampal gyrus in patients with temporal lobe epilepsy (TLE) due to histologically proven mesial temporal lobe sclerosis (MTLS), seizure free for >or=4 years of postsurgical follow-up. METHODS Forty-six (23 male) TLE patients, operated on between 1996 and 2001, with histopathologic diagnosis of MTLS, and a postsurgical follow-up of >or=4 years, had their temporal lobe structures manually segmented, measured, and compared with those of 23 normal volunteers, paired as groups for sex, age, and handedness. RESULTS The mean volumes of the contralateral temporal pole, hippocampus, and parahippocampal gyrus in TLE patients were significantly lower than those in controls. CONCLUSIONS MRI volumetric data show that the damage in TLE due to MTS may be more widespread and bilateral, even in patients with unilateral TLE by clinical and neurophysiological criteria. Our results are relevant to the discussion of epileptogenic mechanisms in TLE.
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Affiliation(s)
- David Araújo
- Department of Neurology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil
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Dickson JM, Wilkinson ID, Howell SJL, Griffiths PD, Grünewald RA. Idiopathic generalised epilepsy: a pilot study of memory and neuronal dysfunction in the temporal lobes, assessed by magnetic resonance spectroscopy. J Neurol Neurosurg Psychiatry 2006; 77:834-40. [PMID: 16574726 PMCID: PMC2117498 DOI: 10.1136/jnnp.2005.086918] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND The memory deficits in patients with temporal lobe epilepsy (TLE) are associated with epileptogenic lesions of the temporal lobes, especially hippocampal sclerosis. Memory deficits have been extensively studied in TLE, but the presence of pre-existing temporal lobe abnormality has confounded studies on the relationship between memory dysfunction and seizure activity. Idiopathic generalised epilepsy (IGE) is characterised by primary generalised seizures and is found to occur in the absence of any macroscopic brain abnormalities. IGE is therefore ideal for investigations on the effects of seizure activity on memory and cognition. AIM AND METHODS Magnetic resonance spectroscopy (MRS) and neuropsychological testing were used to investigate the relationship between epileptic seizures, memory performance and neuronal dysfunction in the temporal lobes of a group of patients with IGE. 30 patients and 15 healthy controls participated in the study. RESULTS Patients with IGE were found to perform worse than controls on tests of speed of information processing, general cognitive performance and a range of memory tests, including face recognition, word recognition, verbal recall and complex figure recall. The performance of the patient group on the visual recognition and verbal recall sections of the Doors and People Test was found to correlate with MRS ratios of N-acetyl aspartate:choline and N-acetyl aspartate:creatine in the temporal lobes. CONCLUSION This result supports the hypothesis that memory deficits in epilepsy may be due to neuronal dysfunction secondary to epileptic activity itself in the absence of any macroscopic lesions in the temporal lobes.
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Affiliation(s)
- J M Dickson
- Department of Biomedical Science, University of Sheffield, Sheffield, UK.
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45
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Rauchs G, Blaizot X, Giffard C, Baron JC, Insausti R, Chavoix C. Imaging visual recognition memory network by PET in the baboon: perirhinal cortex heterogeneity and plasticity after perirhinal lesion. J Cereb Blood Flow Metab 2006; 26:301-9. [PMID: 16094318 DOI: 10.1038/sj.jcbfm.9600203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We recently mapped the visual recognition memory network in the behaving baboon using a positron emission tomography (PET) activation paradigm with 18F-fluoro-deoxyglucose during a visual delayed matching-to-sample task. This study confirmed the key role of the perirhinal cortex and documented an unexpected left-sided advantage. Specific contribution of each subdivision of the perirhinal cortex has, however, never been investigated. Furthermore, although alteration to the perirhinal cortex has been implicated in several brain disorders, putative plasticity within the entire brain network after perirhinal damage remains largely unknown. To confirm our previous data and to investigate these latter issues, we used our PET activation paradigm on a second healthy baboon before and after 16 months after bilateral excitotoxic lesions of the perirhinal cortex. Activation common to our two healthy baboons occurred only in the left rostroventral perirhinal cortex (i.e., areas 36pm and rostral 36r) and insular cortex. Although histologic analysis disclosed that the perirhinal lesions achieved in the present baboon were essentially caudal to this preoperatively activated area, memory performance was severely impaired. Concomitant with this long-lasting cognitive deficit, changes in the neural network implicated in the task were observed, involving disappearance of the preoperative activations and appearance of a significant activation of the frontal and occipital cortices. However, different activation patterns were found in the first and last eight postoperative months. These findings highlight the functional heterogeneity of the perirhinal cortex and evidence progressive plasticity after perirhinal cortex damage.
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46
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Abstract
Functional MRI (fMRI) is a useful tool for noninvasively localizing areas in the brain involved in specific cognitive functions. Since its introduction, there has been considerable speculation regarding the role it may play in the presurgical assessment of temporal lobe epilepsy (TLE). This review considers the progress made to date in using fMRI to investigate memory processing in the medial temporal lobe in normal subjects and in those with TLE. Results so far suggest that fMRI will be incorporated into the presurgical assessment of TLE in the coming years to improve definition of eloquent cerebral areas, with the objective of minimizing the adverse cognitive sequelae of anterior temporal lobe resection.
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Affiliation(s)
- H W Robert Powell
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College of London and MRI Unit, National Society for Epilepsy, Buckinghamshire, U.K.
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47
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Vingerhoets G, Deblaere K, Backes WH, Achten E, Boon P, Boon PJ, Hofman P, Vermeulen J, Vonck K, Wilmink J, Aldenkamp AP. Lessons for neuropsychology from functional MRI in patients with epilepsy. Epilepsy Behav 2004; 5 Suppl 1:S81-9. [PMID: 14725851 DOI: 10.1016/j.yebeh.2003.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This contribution aims to review the major findings of pre- and postsurgical functional magnetic resonance imaging (fMRI) in patients with refractory epilepsy from a neuropsychological perspective. We compared the contribution of fMRI with the intracarotid amytal procedure (IAP) with respect to functional mapping of language and memory in patients with therapy-resistant epilepsy. We conclude that using comprehensive language paradigms, fMRI has been able (1) to provide estimates of the degree of language lateralization including the degree of involvement of the nondominant hemisphere, (2) to provide information on the location of its activated network during expressive and receptive language, and (3) to help delineate eloquent language regions in the vicinity of the surgical target, thus preventing postoperative complications. The contribution of the frequently observed nondominant hemisphere activation to language should be explored and its clinical relevance determined. Evidence from fMRI studies is accumulating that reorganization of cognitive and motor function favors the activation of contralateral homotopic areas, although this process is far from understood. The exact functional contribution of atypical areas of activation should be investigated critically. In the presurgical evaluation process, detailed and reliable localization of language and memory functions of the individual patient is mandatory and should be the ultimate goal in the development of comprehensive clinical fMRI protocols.
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Affiliation(s)
- Guy Vingerhoets
- Laboratory for Neuropsychology, Ghent University, De Pintelaan 185, B-9000 Ghent, Belgium.
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Zubler F, Seeck M, Landis T, Henry F, Lazeyras F. Contralateral medial temporal lobe damage in right but not left temporal lobe epilepsy: a (1)H magnetic resonance spectroscopy study. J Neurol Neurosurg Psychiatry 2003; 74:1240-4. [PMID: 12933926 PMCID: PMC1738688 DOI: 10.1136/jnnp.74.9.1240] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Proton magnetic resonance spectroscopy (MRS) of the hippocampus is useful in lateralising the epileptic focus in temporal lobe epilepsy for subsequent surgical resection. Previous studies have reported abnormal contralateral MRS values in up to 50% of the patients. OBJECTIVE To identify the contributing factors to contralateral damage, as determined by MRS, and its extension in patients with temporal lobe epilepsy. METHODS Single voxel MRS was carried out in the hippocampus and lateral temporal neocortex of both hemispheres in 13 patients with left temporal lobe epilepsy (LTLE) and 16 patients with right temporal lobe epilepsy (RTLE). All patients had mesial temporal lobe epilepsy with hippocampal sclerosis. Controls were 21 healthy volunteers of comparable age. RESULTS Consistent with previous studies, the NAA/(Cho+Cr) ratio was abnormally low in the hippocampus ipsilateral to the focus (p < 0.0001), and there were lower values in both patient groups in the ipsilateral temporal neocortex (p < 0.0001). Patients with RTLE had left hippocampal MRS anomalies (p = 0.0018), whereas the right hippocampus seemed to be undamaged in LTLE patients. CONCLUSIONS Unilateral mesial temporal lobe epilepsy is associated with widespread metabolic abnormalities which involve contralateral mesial and neocortical temporal lobe structures. These abnormalities appear to be more pronounced in patients with RTLE.
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Affiliation(s)
- F Zubler
- Laboratory for Presurgical Epilepsy Evaluation Unit, "Functional Neurology and Neurosurgery" Programme of the Universities Lausanne and Geneva, Switzerland
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