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Temporal lobe epilepsy and tractography

Vera Dinkelacker, Sophie Dupont, Séverine Samson
The new classification of epilepsy stratifies the disease into an acute level, based on seizures, and an overarching chronic level of epileptic syndromes (Berg et al., 2010). In this new approach, seizures are considered either to originate and evolve in unilateral networks or to rapidly encompass both hemispheres. This concept extends the former vision of focal and generalized epilepsies to a genuine pathology of underlying networks. These key aspects of the new classification can be linked to the concept of cognitive curtailing in focal epilepsy...
October 17, 2016: Epilepsy & Behavior: E&B
Sananthan Sivakanthan, Elliot Neal, Ryan Murtagh, Fernando L Vale
BACKGROUND: Diffusion tensor imaging (DTI) is a relatively new imaging modality that has found many peri-operative applications in neurosurgery. METHODS: A comprehensive survey of the applications of diffusion tensor imaging (DTI) in planning for temporal lobe epilepsy surgery was conducted. The presentation of this literature is supplemented by a case illustration. RESULTS: The authors have found that DTI is well utilized in epilepsy surgery, primarily in the tractography of Meyer's loop...
November 2016: Acta Neurochirurgica
Mohammad-Reza Nazem-Zadeh, Susan M Bowyer, John E Moran, Esmaeil Davoodi-Bojd, Andrew Zillgitt, Barbara J Weiland, Hassan Bagher-Ebadian, Fariborz Mahmoudi, Kost Elisevich, Hamid Soltanian-Zadeh
Magnetoencephalography (MEG) is a noninvasive imaging method for localization of focal epileptiform activity in patients with epilepsy. Diffusion tensor imaging (DTI) is a noninvasive imaging method for measuring the diffusion properties of the underlying white matter tracts through which epileptiform activity is propagated. This study investigates the relationship between the cerebral functional abnormalities quantified by MEG coherence and structural abnormalities quantified by DTI in mesial temporal lobe epilepsy (mTLE)...
July 2016: Brain Topography
Marta Szmuda, Tomasz Szmuda, Janusz Springer, Marianna Rogowska, Agnieszka Sabisz, Mirosława Dubaniewicz, Maria Mazurkiewicz-Bełdzińska
PURPOSE: Recent years brought several experimental and clinical reports applying diffusion tensor tractography imaging (DTI) of the brain in epilepsy. This study was aimed to evaluate current evidence for adding the DTI sequence to the standard diagnostic magnetic resonance imaging (MRI) protocol in pediatric epilepsy. MATERIAL AND METHODS: Rapid and qualitative systematic review (RAE, Rapid Evidence Assessment), aggregating relevant studies from the recent 7 years...
2016: Neurologia i Neurochirurgia Polska
Hisaji Imamura, Riki Matsumoto, Shigetoshi Takaya, Tomokazu Nakagawa, Akihiro Shimotake, Takayuki Kikuchi, Nobukatsu Sawamoto, Takeharu Kunieda, Nobuhiro Mikuni, Susumu Miyamoto, Hidenao Fukuyama, Ryosuke Takahashi, Akio Ikeda
OBJECTIVES: To identify the specific change of white matter integrity that occurs in the brain network related to epileptic activity in patients with mesial temporal lobe epilepsy (MTLE). METHODS: We recruited 18 patients with MTLE and 18 healthy subjects. In MTLE patients, the remote functional-deficit zone was delineated using fluorodeoxyglucose positron emission tomography as an extratemporal region showing glucose hypometabolism. Using diffusion magnetic resonance imaging tractography, we defined a seizure propagation tract (PT) as a white matter pathway that connects the focus with a remote functional deficit zone...
February 2016: Epilepsy Research
Michel Modo, T Kevin Hitchens, Jessie R Liu, R Mark Richardson
Understanding the neurobiology and functional connectivity of hippocampal structures is essential for improving the treatment of mesial temporal lobe epilepsy. At the macroscale, in vivo MRI often reveals hippocampal atrophy and decreased fractional anisotropy, whereas at the microscopic scale, there frequently is evidence of neuronal loss and gliosis. Mossy fiber sprouting in the dentate gyrus (DG), with evidence of glutamatergic synapses in the stratum moleculare (SM) putatively originating from granule cell neurons, may also be observed...
February 2016: Human Brain Mapping
Brian L Edlow, Jennifer A McNab, Thomas Witzel, Hannah C Kinney
Homeostatic adaptations to stress are regulated by interactions between the brainstem and regions of the forebrain, including limbic sites related to respiratory, autonomic, affective, and cognitive processing. Neuroanatomic connections between these homeostatic regions, however, have not been thoroughly identified in the human brain. In this study, we perform diffusion spectrum imaging tractography using the MGH-USC Connectome MRI scanner to visualize structural connections in the human brain linking autonomic and cardiorespiratory nuclei in the midbrain, pons, and medulla oblongata with forebrain sites critical to homeostatic control...
April 2016: Brain Connectivity
Gong-Jun Ji, Zhiqiang Zhang, Qiang Xu, Wei Wei, Jue Wang, Zhengge Wang, Fang Yang, Kangjian Sun, Qing Jiao, Wei Liao, Guangming Lu
To identify the distinct pattern of anatomical network reorganization in surgically refractory mesial temporal lobe epilepsy (MTLE) patients using a longitudinal design. We collected longitudinal diffusion-weighted images of 19 MTLE patients before and after anterior temporal lobectomy. Patients were classified as seizure-free (SF) or nonseizure-free (NSF) at least 1 year after surgery. We constructed whole-brain anatomical networks derived from white matter tractography and evaluated network connectivity measures by graph theoretical analysis...
October 2015: Medicine (Baltimore)
Petros Stylianou, Chen Hoffmann, Ilan Blat, Sagi Harnof
The objective of part one of this review is to present the structural neuroimaging techniques that are currently used to evaluate patients with temporal lobe epilepsy (TLE), and to discuss their potential to define patient eligibility for medial temporal lobe surgery. A PubMed query, using Medline and Embase, and subsequent review, was performed for all English language studies published after 1990, reporting neuroimaging methods for the evaluation of patients with TLE. The extracted data included demographic variables, population and study design, imaging methods, gold standard methods, imaging findings, surgical outcomes and conclusions...
January 2016: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
Seung-Hak Lee, Mansu Kim, Hyunjin Park
Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We suggest starting the incision for selective amygdalohippocampectomy at the inferior temporal gyrus based on diffusion magnetic resonance imaging (MRI) tractography. Diffusion MRI data from 20 normal participants were obtained from Parkinson's Progression Markers Initiative (PPMI) database (www.ppmi-info...
July 2015: Neural Regeneration Research
Christopher D Whelan, Saud Alhusaini, Erik O'Hanlon, Maria Cheung, Parames M Iyer, James F Meaney, Andrew J Fagan, Gerard Boyle, Norman Delanty, Colin P Doherty, Gianpiero L Cavalleri
OBJECTIVE: The identification of "endophenotypes"-measurable variations along the pathways between genes and distal disease state-may help deconstruct focal epilepsies into more sensitive phenomena and improve future efforts to map the genetic underpinnings of the disorder. In this study, we set out to determine if diffusion tensor imaging (DTI)-inferred white matter (WM) alterations represent a suitable structural endophenotype for focal epilepsy. METHODS: We recruited 25 patients with sporadic mesial temporal lobe epilepsy (MTLE) with normal magnetic resonance imaging (MRI) findings, 25 of their gender-matched, asymptomatic siblings, and 60 control subjects...
October 2015: Epilepsia
Vera Dinkelacker, Romain Valabregue, Lionel Thivard, Stéphane Lehéricy, Michel Baulac, Séverine Samson, Sophie Dupont
OBJECTIVE: Medial temporal lobe epilepsy (TLE) with hippocampal sclerosis is often accompanied by widespread changes in ipsilateral and contralateral white matter connectivity. Recent studies have proposed that patients may show pathologically enhanced wiring of the limbic circuits. To better address this issue, we specifically probed connection patterns between hippocampus and thalamus and examined their impact on cognitive function. METHODS: A group of 44 patients with TLE (22 with right and 22 with left hippocampal sclerosis) and 24 healthy control participants were examined with high-resolution T1 imaging, memory functional magnetic resonance imaging (fMRI) and probabilistic diffusion tractography...
August 2015: Epilepsia
Peter N Taylor, Cheol E Han, Jan-Christoph Schoene-Bake, Bernd Weber, Marcus Kaiser
BACKGROUND: Previous studies reported reduced volumes of many brain regions for temporal lobe epilepsy (TLE). It has also been suggested that there may be widespread changes in network features of TLE patients. It is not fully understood, however, how these two observations are related. METHODS: Using magnetic resonance imaging data, we perform parcellation of the brains of 22 patients with left TLE and 39 non-epileptic controls. In each parcellated region of interest (ROI) we computed the surface area and, using diffusion tensor imaging and deterministic tractography, infer the number of streamlines and their average length between each pair of connected ROIs...
2015: NeuroImage: Clinical
Natalie L Voets, Ricarda A L Menke, Saad Jbabdi, Masud Husain, Richard Stacey, Katherine Carpenter, Jane E Adcock
Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction...
November 2015: Cerebral Cortex
Ylva Lilja, Daniel T Nilsson
Diffusion tensor imaging (DTI) tractography (TG) can visualize Meyer's loop (ML), providing important information for the epilepsy surgery team, both for preoperative counseling and to reduce the frequency of visual field defects after temporal lobe resection (TLR). This review highlights significant steps in the TG process, specifically the processing of raw data including choice of TG algorithm and the interpretation and validation of results. A lack of standardization of TG of the optic radiation makes study comparisons challenging...
April 2015: Quantitative Imaging in Medicine and Surgery
H Urbach, H Mast, K Egger, I Mader
Primary goal of magnetic resonance imaging in epilepsy patients is to detect epileptogenic lesions with small lesions best detectable on a 3D FLAIR SPACE sequence with 1 mm(3) voxels. Morphometric analysis of 3D T1-weighted data sets helps to find subtle lesions and may reveal the true extent of a lesion. In further presurgical work-up, language lateralization and spatial relationship of epileptogenic lesions to eloquent cortex and white matter tracts must be evaluated. With clear left lateralization language, fMRI is sufficient; in atypical lateralizations, Wada test and electrical stimulation mapping may be added...
October 2015: Clinical Neuroradiology
Jeffrey D Riley, Brett W Fling, Steven C Cramer, Jack J Lin
OBJECTIVE: Deficits in social cognition are common and significant in people with temporal lobe epilepsy (TLE), but the functional and structural underpinnings remain unclear. The present study investigated how the side of seizure focus impacts face-processing networks in temporal lobe epilepsy. METHODS: We used functional magnetic resonance imaging (fMRI) of a face-processing paradigm to identify face-responsive regions in 24 individuals with unilateral temporal lobe epilepsy (left = 15; right = 9) and 19 healthy controls...
May 2015: Epilepsia
Jija S James, Ashalatha Radhakrishnan, Bejoy Thomas, Mini Madhusoodanan, Chandrashekharan Kesavadas, Mathew Abraham, Ramshekhar Menon, Chaturbhuj Rathore, George Vilanilam
PURPOSE: Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population. METHODS: DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL...
February 2015: Epilepsy Research
Daniel S Barron, Peter T Fox, Heath Pardoe, Jack Lancaster, Larry R Price, Karen Blackmon, Kristen Berry, Jose E Cavazos, Ruben Kuzniecky, Orrin Devinsky, Thomas Thesen
Noninvasive markers of brain function could yield biomarkers in many neurological disorders. Disease models constrained by coordinate-based meta-analysis are likely to increase this yield. Here, we evaluate a thalamic model of temporal lobe epilepsy that we proposed in a coordinate-based meta-analysis and extended in a diffusion tractography study of an independent patient population. Specifically, we evaluated whether thalamic functional connectivity (resting-state fMRI-BOLD) with temporal lobe areas can predict seizure onset laterality, as established with intracranial EEG...
2015: NeuroImage: Clinical
Brunno M Campos, Ana C Coan, Guilherme C Beltramini, Min Liu, Clarissa L Yassuda, Enrico Ghizoni, Christian Beaulieu, Donald W Gross, Fernando Cendes
OBJECTIVE: To evaluate white matter (WM) integrity of distinct groups of patients with antiepileptic drug (AED)-resistant localization-related epilepsies. METHODS: We used diffusion tensor imaging (DTI) fiber-tractography and voxel-based morphometry (VBM) to investigate differences of WM micro- and macrostructural integrity in patients with different drug-resistant localization-related epilepsies: 17 with temporal lobe epilepsy with magnetic resonance imaging (MRI) signs of hippocampal sclerosis (TLE-HS), 17 with TLE and normal MRI (TLE-NL), 14 with frontal lobe epilepsy and subtle MRI signs of focal cortical dysplasia (FLE-FCD), and 112 healthy controls...
January 2015: Epilepsia
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