Abstract Advanced, noninvasive imaging has revolutionized our understanding of language networks in the brain and is reshaping our approach to the presurgical evaluation of patients with epilepsy. Functional magnetic resonance imaging (fMRI) has had the greatest impact, unveiling the complexity of language organization and reorganization in patients with epilepsy both pre- and postoperatively, while volumetric MRI and diffusion tensor imaging have led to a greater appreciation of structural and microstructural correlates of language dysfunction in different epilepsy syndromes. In this article, we review recent literature describing how unimodal and multimodal imaging has advanced our knowledge of language networks and their plasticity in epilepsy, with a focus on the most frequently studied epilepsy syndrome in adults, temporal lobe epilepsy ( TLE ). We also describe how new analytic techniques (i.e., graph theory) are leading to a refined characterization of abnormal brain connectivity, and how subject-specific imaging profiles combined with clinical data may enhance the prediction of both seizure and language outcomes following surgical interventions.
#2Neda Bernasconi(Montreal Neurological Institute and Hospital)H-Index: 49
Last. Andrea Bernasconi(Montreal Neurological Institute and Hospital)H-Index: 61
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: Temporal lobe epilepsy (TLE) is the most frequent drug-resistant epilepsy in adults and commonly associated with variable degrees of mesiotemporal atrophy on magnetic resonance imaging (MRI). Analyses of inter-regional connectivity have unveiled disruptions in large-scale cortico-cortical networks; little is known about the topological organization of the mesiotemporal lobe, the limbic subnetwork central to the disorder. We generated covariance networks based on high-resolution MRI surface-sha...
OBJECT Predicting cognitive function following resective surgery remains an important clinical goal. Each MRI neuroimaging technique can potentially provide unique and distinct insight into changes that occur in the structural or functional organization of “at-risk” cognitive functions. The authors tested for the singular and combined power of 3 imaging techniques (functional MRI [fMRI], resting state fMRI, diffusion tensor imaging) to predict cognitive outcome following left (dominant) anterior...
#2Leonardo Bonilha(MUSC: Medical University of South Carolina)H-Index: 55
Last. Donald W. Gross(U of A: University of Alberta)H-Index: 31
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Abstract Recent years have witnessed a paradigm shift in the study and conceptualization of epilepsy, which is increasingly understood as a network-level disorder. An emblematic case is temporal lobe epilepsy (TLE), the most common drug-resistant epilepsy that is electroclinically defined as a focal epilepsy and pathologically associated with hippocampal sclerosis. In this review, we will summarize histopathological, electrophysiological, and neuroimaging evidence supporting the concept that the...
The impairment in episodic memory system is the best-known cognitive deficit in patients with temporal lobe epilepsy (TLE). Recent studies have shown evidence of semantic disorders, but they have been less studied than episodic memory. The semantic dysfunction in TLE has various cognitive manifestations, such as the presence of language disorders characterized by defects in naming, verbal fluency, or remote semantic information retrieval, which affects the ability of patients to interact with th...
The objective of this review is to resume major neuroimaging findings on language organization and plasticity in patients with focal and refractory epilepsy, to discuss the effect of modulatory variables that should be considered alongside patterns of reorganization, and to propose possible models of language reorganization. The focal and refractory epilepsy provides a real opportunity to investigate various types of language reorganization in different conditions. The ‘chronic’ condition (induc...
Abstract The ability to express oneself verbally is critical for success in academic, occupational, and social domains. Unfortunately, word-finding or “naming” difficulty is the most common cognitive complaint among individuals with temporal lobe epilepsy (TLE), and a substantial body of work over the past several decades has documented naming impairment in left (language-dominant) TLE, with further risk to naming ability following left temporal lobe resection for seizure control. With these fin...
#2Leonardo Bonilha(MUSC: Medical University of South Carolina)H-Index: 55
Last. Bruce P. Hermann(UW: University of Wisconsin-Madison)H-Index: 104
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Abstract Objective Normal childhood development is defined by age-dependent improvement across cognitive abilities, including language, memory, psychomotor speed and executive function. Epilepsy is often associated with a global disruption in cognitive development, however, it is still largely unknown how epilepsy affects the overall organization of overlapping cognitive domains. The aim of the study was to evaluate how childhood epilepsy affects the developmental interrelationships between cogn...
#2Robert Rider(Thomas Jefferson University)H-Index: 1
Last. Joseph I. Tracy(Thomas Jefferson University)H-Index: 32
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Summary Objective This study determined the ability of resting-state functional connectivity (rsFC) graph-theory measures to predict neurocognitive status postsurgery in patients with temporal lobe epilepsy (TLE) who underwent anterior temporal lobectomy (ATL). Methods A presurgical resting-state functional magnetic resonance imaging (fMRI) condition was collected in 16 left and 16 right TLE patients who underwent ATL. In addition, patients received neuropsychological testing pre- and postsurger...
Focal epilepsy is conceived of as activating local areas of the brain as well as engaging regional brain networks. Graph theory represents a powerful quantitative framework for investigation of brain networks. Here we investigate whether functional network changes are present in extratemporal focal epilepsy. Task-free functional magnetic resonance imaging data from 15 subjects with extratemporal epilepsy and 26 age and gender matched healthy controls were used for analysis. Local network propert...
#2Dorian Pustina(Thomas Jefferson University)H-Index: 12
Last. Joseph I. Tracy(Thomas Jefferson University)H-Index: 32
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In temporal lobe epilepsy (TLE), determining the hemispheric specialization for language before surgery is critical to preserving a patient's cognitive abilities post-surgery. To date, the major techniques utilized are limited by the capacity of patients to efficiently realize the task. We determined whether resting-state functional connectivity (rsFC) is a reliable predictor of language hemispheric dominance in right and left TLE patients, relative to controls. We chose three subregions of the ...
Abstract null null Objective null High-resolution protocols used in magnetic resonance imaging (MRI) currently enable the detailed analysis of the hippocampus along with its subfield segmentation. The relationship between episodic memory and the hippocampus is well established, and there is growing evidence that some specific memory processing steps are associated with individual hippocampal segments, but there are inconsistencies in the literature. We focused our analysis on hippocampal subfiel...
#1Rebecca K. Reh(UBC: University of British Columbia)H-Index: 1
#1Rebecca K. Reh(UBC: University of British Columbia)H-Index: 5
Last. Lawrence M. Ward(UBC: University of British Columbia)H-Index: 61
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It is well established that temporal lobe epilepsy-the most common and well-studied form of epilepsy-can impair communication by disrupting social-emotional and language functions. In pediatric epilepsy, where seizures co-occur with the development of critical brain networks, age of onset matters: The earlier in life seizures begin, the worse the disruption in network establishment, resulting in academic hardship and social isolation. Yet, little is known about the processes by which epileptic a...
#1Xinghui He(CSU: Central South University)H-Index: 1
#2Dingyang Liu(CSU: Central South University)H-Index: 10
Last. Zhiquan Yang(CSU: Central South University)H-Index: 2
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Objective: This study aims to evaluate the surgical outcomes and analyze the predictors of surgical outcomes in patients undergoing anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) secondary to focal cortical dysplasia (FCD) type IIIa. Methods: Data on patients with drug-resistant TLE secondary to FCD type IIIa who had undergone ATL at Xiangya Hospital, Central South University from January 2014 to April 2018, were collected retrospectively. International League ...
Functional magnetic resonance imaging (fMRI) is a usable technique to determine hemispheric dominance of language function, but high-quality fMRI images are difficult to acquire in young children. Here we aimed to develop and validate an fMRI approach to reliably determine hemispheric language dominance in young children. We designed two new tasks (story, SR; Letter picture matching, LPM) that aimed to match the interests and the levels of cognitive development of young children. We studied 32 h...
Last. Carrie R. McDonald(UCSD: University of California, San Diego)H-Index: 38
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ABSTRACT Objective The distributed white matter network underlying language leads to difficulties in extracting clinically meaningful summaries of neural alterations leading to language impairment. Here we determine the predictive ability of the structural connectome (SC), compared with global measures of white matter tract microstructure and clinical data, to discriminate language impaired patients with temporal lobe epilepsy (TLE) from TLE patients without language impairment. Methods T1- and ...
Abstract Recent theoretical models of language have emphasised the importance of integration within distributed networks during language processing. This is particularly relevant to young patients with epilepsy, as the topology of the functional network and its dynamics may be altered by the disease, resulting in reorganisation of functional language networks. Thus, understanding connectivity within the language network in patients with epilepsy could provide valuable insights into healthy and p...
Abstract Objective Neuropsychological tests can infer the lateralization of the epileptogenic focus, associating verbal memory to mesial structures in the left temporal lobe and visual or nonverbal memory to the right side. High-field magnetic resonance imaging (MRI) with high-resolution protocols allows acquisitions suitable for advanced postprocessing with precise volumetry of brain structures, and functional MRI demonstrates evidence that epilepsy should be seen as a network pathology, involv...
Abstract Children with epilepsy can experience significant cognitive dysfunction that can lead to academic underachievement. Traditionally believed to be primarily due to the effects of factors such as the chronicity of epilepsy, medication effects, or the location of the primary epileptogenic lesion;, recent evidence has indicated that disruption of cognition-specific distributed neural networks may play a significant role as well. Specifically, over the last decade, researchers have begun to c...
#1Erik Kaestner(UCSD: University of California, San Diego)H-Index: 10
#2Anny Reyes(UCSD: University of California, San Diego)H-Index: 10
Last. Carrie R. McDonald(UCSD: University of California, San Diego)H-Index: 38
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OBJECTIVE: To identify neuroimaging and clinical biomarkers associated with a language-impaired phenotype in refractory temporal lobe epilepsy (TLE). METHODS: Eighty-five patients with TLE were characterized as language-impaired (TLE-LI) or non-language-impaired (TLE-NLI) based on comprehensive neuropsychological testing. Structural magnetic resonance imaging (MRI), diffusion tensor imaging, and functional MRI (fMRI) were obtained in patients and 47 healthy controls (HC). fMRI activations and co...