1
|
Freire IS, Lopes TS, Afonso SG, Pereira DJ. From images to insights: a neuroradiologist's practical guide on white matter fiber tract anatomy and DTI patterns for pre-surgical planning. Neuroradiology 2024:10.1007/s00234-024-03362-7. [PMID: 38635028 DOI: 10.1007/s00234-024-03362-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 04/13/2024] [Indexed: 04/19/2024]
Abstract
INTRODUCTION Diffusion tensor imaging (DTI) is a valuable non-invasive imaging modality for mapping white matter tracts and assessing microstructural integrity, and can be used as a "biomarker" in diagnosis, differentiation, and therapeutic monitoring. Although it has gained clinical importance as a marker of neuropathology, limitations in its interpretation underscore the need for caution. METHODS This review provides an overview of the principles and clinical applicability of DTI. We focus on major white matter fiber bundles, detailing their normal anatomy and pathological DTI patterns, with emphasis on tracts routinely requested in our neurosurgical department in the preoperative context (uncinate fasciculus, arcuate fasciculus, pyramidal pathway, optic radiation, and dentatorubrothalamic tract). RESULTS We guide neuroradiologists and neurosurgeons in defining volumes of interest for mapping individual tracts and demonstrating their 3D reconstructions. The intricate trajectories of white matter tracts pose a challenge for accurate fiber orientation recording, with each bundle exhibiting specific characteristics. Tracts adjacent to brain lesions are categorized as displaced, edematous, infiltrated, or disrupted, illustrated with clinical cases of brain neoplasms. To improve structured reporting, we propose a checklist of topics for inclusion in imaging evaluations and MRI reports. CONCLUSION DTI is emerging as a powerful tool for assessing microstructural changes in brain disorders, despite some challenges in standardization and interpretation. This review serves an educational purpose by providing guidance for fiber monitoring and interpretation of pathological patterns observed in clinical cases, highlighting the importance and potential pitfalls of DTI in neuroradiology and surgical planning.
Collapse
Affiliation(s)
- Inês S Freire
- Department of Neuroradiology - Centro Hospitalar Universitário de Lisboa Central (CHULC), Rua José António Serrano, 1150-199, Lisbon, Portugal.
- NOVA Medical School, Universidade Nova de Lisboa, Lisbon, Portugal.
| | - Tânia S Lopes
- Institute of Nuclear Sciences Applied to Health (ICNAS), Coimbra, Portugal
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Coimbra, Portugal
| | - Sónia G Afonso
- Institute of Nuclear Sciences Applied to Health (ICNAS), Coimbra, Portugal
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Coimbra, Portugal
| | - Daniela J Pereira
- Institute of Nuclear Sciences Applied to Health (ICNAS), Coimbra, Portugal
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Coimbra, Portugal
- Functional Unit of Neuroradiology - Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal
| |
Collapse
|
2
|
Al Busaidi A, Gangemi E, Wastling S, Berg ASVD, Mancini L, Yousry T. Functional MRI but not white matter fibre dissection identifies language dominance. Eur Radiol 2023; 33:6081-6093. [PMID: 37410110 DOI: 10.1007/s00330-023-09838-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 03/22/2023] [Accepted: 04/08/2023] [Indexed: 07/07/2023]
Abstract
OBJECTIVES Lateralisation of some language pathways has been reported in the literature using diffusion tractography, which is more feasible than functional magnetic resonance imaging (fMRI) in challenging patients. Our retrospective study investigates whether a correlation exists between threshold-independent fMRI language lateralisation and structural lateralisation using tractography in healthy controls and brain tumour patients. METHODS Fifteen healthy subjects and 61 patients underwent language fMRI and diffusion-weighted MRI. A regional fMRI laterality index (LI) was calculated. Tracts dissected were the arcuate fasciculus (long direct and short indirect tracts), uncinate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and frontal aslant tract. An asymmetry index (AI) for each tract was calculated using tract volume analysed with single tensor (ST) and spherical deconvolution (SD) models, as well as hindrance modulated orientational anisotropy (HMOA) for SD tracts. Linear regression assessed the correlation between LI and AI. RESULTS In all subjects, there was no significant correlation between LI and AI for any of the dissected tracts. Significant correlations were only found when handedness for controls and tumour volume for patients were included as covariates. In handedness subgroups, the average AI of some tracts showed the same laterality as LI, and some the opposite. Discordant results were observed for ST- and SD-based AIs. CONCLUSIONS Our results do not support using tractography in the assessment of language lateralisation. The discordant results between ST and SD indicate that either the structural lateralisation of dissected tracts is less robust than functional lateralisation, or tractography is not sensitive methodology. Other diffusion analysis approaches should be developed. CLINICAL RELEVANCE STATEMENT Although diffusion tractography may be more feasible than fMRI in challenging tumour patients and where sedation or anaesthesia is required, our results do not currently recommend replacing fMRI with tractography using volume or HMOA in the assessment of language lateralisation. KEY POINTS • No correlation found between fMRI and tractography in language lateralisation. • Discordance between asymmetry indices of different tractography models and metrics. • Tractography not currently recommended in language lateralisation assessment.
Collapse
Affiliation(s)
- Ayisha Al Busaidi
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK.
- Department of Neuroradiology, King's College Hospital NHS Foundation Trust, London, Denmark Hill, SE5 9RS, UK.
| | - Emma Gangemi
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK
- Radiology Department, Ospedale Dei Castelli, Via Nettunense, Km 11,5, 00040, Rome, Italy
| | - Stephen Wastling
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK
- Neuroradiological Academic Unit, Department of Brain, Repair and Rehabilitation, University College London Institute of Neurology, Queen Square, WC1N 3BG, London, UK
| | - Aaike S van den Berg
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK
- Department of Radiology & Nuclear Medicine, Erasmus MC - University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - Laura Mancini
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK
- Neuroradiological Academic Unit, Department of Brain, Repair and Rehabilitation, University College London Institute of Neurology, Queen Square, WC1N 3BG, London, UK
| | - Tarek Yousry
- Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, Queen Square, London, WC1N 3BG, UK
- Neuroradiological Academic Unit, Department of Brain, Repair and Rehabilitation, University College London Institute of Neurology, Queen Square, WC1N 3BG, London, UK
| |
Collapse
|
3
|
Shekari E, Nozari N. A narrative review of the anatomy and function of the white matter tracts in language production and comprehension. Front Hum Neurosci 2023; 17:1139292. [PMID: 37051488 PMCID: PMC10083342 DOI: 10.3389/fnhum.2023.1139292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 02/24/2023] [Indexed: 03/28/2023] Open
Abstract
Much is known about the role of cortical areas in language processing. The shift towards network approaches in recent years has highlighted the importance of uncovering the role of white matter in connecting these areas. However, despite a large body of research, many of these tracts’ functions are not well-understood. We present a comprehensive review of the empirical evidence on the role of eight major tracts that are hypothesized to be involved in language processing (inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, extreme capsule, middle longitudinal fasciculus, superior longitudinal fasciculus, arcuate fasciculus, and frontal aslant tract). For each tract, we hypothesize its role based on the function of the cortical regions it connects. We then evaluate these hypotheses with data from three sources: studies in neurotypical individuals, neuropsychological data, and intraoperative stimulation studies. Finally, we summarize the conclusions supported by the data and highlight the areas needing further investigation.
Collapse
Affiliation(s)
- Ehsan Shekari
- Department of Neuroscience, Iran University of Medical Sciences, Tehran, Iran
| | - Nazbanou Nozari
- Department of Psychology, Carnegie Mellon University, Pittsburgh, PA, United States
- Center for the Neural Basis of Cognition (CNBC), Pittsburgh, PA, United States
- *Correspondence: Nazbanou Nozari
| |
Collapse
|
4
|
Cao J, Yin Z, Chen B, Chang M, Li C, Fan G, Cui L. Unilaterally disrupted structural and functional connectivity of the fronto-limbic system in idiopathic hypogonadotropic hypogonadism. Clin Endocrinol (Oxf) 2022; 97:604-611. [PMID: 35274757 DOI: 10.1111/cen.14722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/06/2022] [Accepted: 02/12/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Idiopathic hypogonadotropic hypogonadism (IHH) is rare and can either be associated with normal or defective olfactory sensation, classified as normosmic IHH (nIHH) or Kallmann syndrome (KS). We do not yet understand the central processing pathways in the olfactory system. We aimed to compare the resting-state structural and functional connectivity (FC) of olfactory neural pathways in patients with IHH. We hypotheses that alterations of structural connectivity and FC may exist in the olfactory cortex pathways in IHH patients. DESIGN STRUCTURAL AND FUNCTIONAL CONNECTIVITY DATA RESULTS BETWEEN TWO GROUPS WERE ANALYZED: Patients: Twenty-five IHH patients (13 nIHH patients and 12 KS patients) were recruited from the Department of Endocrinology and were assessed. A total of 25 age-matched healthy male controls were recruited from the community. MEASUREMENTS All subjects underwent diffusion tensor imaging and functional magnetic resonance imaging (fMRI) scans. Structural and functional connectivity data analyses were then performed. Pearson's correlation analyses were performed to investigate the correlations between the fractional anisotropy (FA) value and FC strength, showing significant differences among the three groups separately. RESULTS Compared with the HC group, FA value in the right uncinate fasciculus (UF) decreased significantly in the IHH group. The olfactory cortex FC values of the right gyrus rectus, orbitofrontal cortex (OFC) and right middle temporal gyrus in the IHH group were decreased compared with those in the HC group. Moreover, there were significant negative correlations between right UF FA and olfactory cortex-FC to both the gyrus rectus and OFC within the HC group (p < .05). CONCLUSION Our findings suggest that alterations of structural and FC support the presence of neurobiological disruptions in IHH patients, particularly a specific structural-functional asymmetry disruption may exist in the olfactory cortex pathways in IHH patients.
Collapse
Affiliation(s)
- Jibin Cao
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Zhiyang Yin
- Department of Psychiatry, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Boyu Chen
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Miao Chang
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Chao Li
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Guoguang Fan
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Lingling Cui
- Department of Radiology, The First Hospital of China Medical University, Shenyang, Liaoning, China
| |
Collapse
|
5
|
Li X, Jiang Y, Li W, Qin Y, Li Z, Chen Y, Tong X, Xiao F, Zuo X, Gong Q, Zhou D, Yao D, An D, Luo C. Disrupted functional connectivity in white matter resting-state networks in unilateral temporal lobe epilepsy. Brain Imaging Behav 2021; 16:324-335. [PMID: 34478055 DOI: 10.1007/s11682-021-00506-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2021] [Indexed: 02/08/2023]
Abstract
Unilateral temporal lobe epilepsy (TLE) is the most common type of focal epilepsy characterized by foci in the unilateral temporal lobe grey matters of regions such as the hippocampus. However, it remains unclear how the functional features of white matter are altered in TLE. In the current study, resting-state functional magnetic resonance imaging (fMRI) was performed on 71 left TLE (LTLE) patients, 79 right TLE (RTLE) patients and 47 healthy controls (HC). Clustering analysis was used to identify fourteen white matter networks (WMN). The functional connectivity (FC) was calculated among WMNs and between WMNs and grey matter. Furthermore, the FC laterality of hemispheric WMNs was assessed. First, both patient groups showed decreased FCs among WMNs. Specifically, cerebellar white matter illustrated decreased FCs with the cerebral superficial WMNs, implying a dysfunctional interaction between the cerebellum and the cerebral cortex in TLE. Second, the FCs between WMNs and the ipsilateral hippocampus (grey matter foci) were also reduced in patient groups, which may suggest insufficient functional integration in unilateral TLE. Interestingly, RTLE showed more severe abnormalities of white matter FCs, including links to the bilateral hippocampi and temporal white matter, than LTLE. Taken together, these findings provide functional evidence of white matter abnormalities, extending the understanding of the pathological mechanism of white matter impairments in unilateral TLE.
Collapse
Affiliation(s)
- Xuan Li
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Yuchao Jiang
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Wei Li
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Yingjie Qin
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Zhiliang Li
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Yan Chen
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Xin Tong
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Fenglai Xiao
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Xiaojun Zuo
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Qiyong Gong
- Huaxi MR Research Center, Department of Radiology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Dong Zhou
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Dezhong Yao
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China
| | - Dongmei An
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610054, People's Republic of China
| | - Cheng Luo
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Lab for Neuroinformation, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of China, Second North Jianshe Road, Chengdu, 610054, People's Republic of China.
| |
Collapse
|
6
|
Liakos F, Komaitis S, Drosos E, Neromyliotis E, Skandalakis GP, Gerogiannis AI, Kalyvas AV, Troupis T, Stranjalis G, Koutsarnakis C. The Topography of the Frontal Terminations of the Uncinate Fasciculus Revisited Through Focused Fiber Dissections: Shedding Light on a Current Controversy and Introducing the Insular Apex as a Key Anatomoclinical Area. World Neurosurg 2021; 152:e625-e634. [PMID: 34144169 DOI: 10.1016/j.wneu.2021.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Recent studies advocate a connectivity pattern wider than previously believed of the uncinate fasciculus that extends to the ventrolateral and dorsolateral prefrontal cortices. These new percepts on the connectivity of the tract suggest a more expansive role for the uncinate fasciculus. Our aim was to shed light on this controversy through fiber dissections. METHODS Twenty normal adult human formalin-fixed cerebral hemispheres were used. Focused dissections on the insular, orbitofrontal, ventromedial, ventrolateral, and dorsolateral prefrontal areas were performed to record the topography of the frontal terminations of the uncinate fasciculus. RESULTS Three discrete fiber layers were consistently disclosed: the first layer was recorded to terminate at the posterior orbital gyrus and pars orbitalis, the second layer at the posterior two thirds of the gyrus rectus, and the last layer at the posterior one third of the paraolfactory gyrus. The insular apex was documented as a crucial landmark regarding the topographic differentiation of the uncinate and occipitofrontal fasciculi (i.e., fibers that travel ventrally belong to the uncinate fasciculus whereas those traveling dorsally are occipitofrontal fibers). CONCLUSIONS The frontal terminations of the uncinate fasciculus were consistently documented to project to the posterior orbitofrontal area. The area of the insular apex is introduced for the first time as a crucial surface landmark to effectively distinguish the stems of the uncinate and occipitofrontal fasciculi. This finding could refine the spatial resolution of awake subcortical mapping, especially for insular lesions, and improve the accuracy of in vivo diffusion tensor imaging protocols.
Collapse
Affiliation(s)
- Faidon Liakos
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Spyridon Komaitis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece; Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelos Drosos
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Eleftherios Neromyliotis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece; Hellenic Center for Neurosurgical Research, "Petros Kokkalis", Athens, Greece
| | | | | | - Aristotelis V Kalyvas
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece; Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Theodore Troupis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - George Stranjalis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece; Hellenic Center for Neurosurgical Research, "Petros Kokkalis", Athens, Greece
| | - Christos Koutsarnakis
- Athens Microneurosurgery Laboratory, Evangelismos Hospital, Athens, Greece; Department of Neurosurgery, Evangelismos Hospital, National and Kapodistrian University of Athens, Athens, Greece; Edinburgh Microneurosurgery Education Laboratory, Department of Clinical Neurosciences, Edinburgh, United Kingdom; Department of Anatomy, Medical School, National and Kapodistrian University of Athens, Athens, Greece; Hellenic Center for Neurosurgical Research, "Petros Kokkalis", Athens, Greece.
| |
Collapse
|
7
|
Tractography-Based Analysis of Morphological and Anatomical Characteristics of the Uncinate Fasciculus in Human Brains. Brain Sci 2020; 10:brainsci10100709. [PMID: 33036125 PMCID: PMC7601025 DOI: 10.3390/brainsci10100709] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 12/20/2022] Open
Abstract
(1) Background: The uncinate fasciculus (UF) is a white matter bundle connecting the prefrontal cortex and temporal lobe. The functional role of the uncinate fasciculus is still uncertain. The role of the UF is attributed to the emotional empathy network. The present study aimed to more accurately the describe anatomical variability of the UF by focusing on the volume of fibers and testing for correlations with sex and age. (2) Material and Methods: Magnetic resonance imaging of adult patients with diffusion tensor imaging (DTI) was performed on 34 patients. The total number of fibers, volume of UF, and number of tracts were processed using DSI studio software. The DSI studio allows for mapping of different nerve pathways and visualizing of the obtained results using spatial graphics. (3) Results: The total number of UF tracts was significantly higher in the right hemisphere compared to the left hemisphere (right M ± SD = 52 ± 24; left: 39 ± 25, p < 0.05). A hook-shaped UF was the most common variant (91.7%). The UF volumes were larger in men (1410 ± 150.7 mm3) as compared to women (1325 ± 133.2 mm3) (p < 0.05). The mean fractional anisotropy (FA) values of the UF were significantly larger on the left side 0.597, while the right UF had an average of 0.346 (p < 0.05). Patients older than 50 years old had a significantly higher value of mean diffusivity (MD) (p = 0.034). In 73.5% of patients, a greater number of fibers terminated in the inferior part of the inferior frontal gyrus. (4) Conclusions: The morphological characteristics of the UF, unlike the shape, are associated with sex and are characterized by hemispheric dominance. These findings confirm the results of the previous studies. Future research should examine the potential correlation among the UF volume, number of fibers, and total brain volume in both sexes and patient psychological state.
Collapse
|
8
|
Delgado-Fernández J, García-Pallero MÁ, Manzanares-Soler R, Martín-Plasencia P, Blasco G, Frade-Porto N, Navas-García M, Pulido P, Sola RG, Torres CV. Language hemispheric dominance analyzed with magnetic resonance DTI: correlation with the Wada test. J Neurosurg 2020; 134:1703-1710. [PMID: 32707542 DOI: 10.3171/2020.4.jns20456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 04/22/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Language lateralization is a major concern in some patients with pharmacoresistant epilepsy who will face surgery; in these patients, hemispheric dominance testing is essential to avoid further complications. The Wada test is considered the gold standard examination for language localization, but is invasive and requires many human and material resources. Functional MRI and tractography with diffusion tensor imaging (DTI) have demonstrated that they could be useful for locating language in epilepsy surgery, but there is no evidence of the correlation between the Wada test and DTI MRI in language dominance. METHODS The authors performed a retrospective review of patients who underwent a Wada test before epilepsy surgery at their institution from 2012 to 2017. The authors retrospectively analyzed fractional anisotropy (FA), number and length of fibers, and volume of the arcuate fasciculus and uncinate fasciculus, comparing dominant and nondominant hemispheres. RESULTS Ten patients with temporal lobe epilepsy were reviewed. Statistical analysis showed that the mean FA of the arcuate fasciculus in the dominant hemisphere was higher than in the nondominant hemisphere (0.369 vs 0.329, p = 0.049). Also, the number of fibers in the arcuate fasciculus was greater in the dominant hemisphere (881.5 vs 305.4, p = 0.003). However, no differences were found in the FA of the uncinate fasciculus or number of fibers between hemispheres. The length of fibers of the uncinate fasciculus was longer in the dominant side (74.4 vs 50.1 mm, p = 0.05). Volume in both bundles was more prominent in the dominant hemisphere (12.12 vs 6.48 cm3, p = 0.004, in the arcuate fasciculus, and 8.41 vs 4.16 cm3, p = 0.018, in the uncinate fasciculus). Finally, these parameters were compared in patients in whom the seizure focus was situated in the dominant hemisphere: FA (0.37 vs 0.30, p = 0.05), number of fibers (114.4 vs 315.6, p = 0.014), and volume (12.58 vs 5.88 cm3, p = 0.035) in the arcuate fasciculus were found to be statistically significantly higher in the dominant hemispheres. Linear discriminant analysis of FA, number of fibers, and volume of the arcuate fasciculus showed a correct discrimination in 80% of patients (p = 0.024). CONCLUSIONS The analysis of the arcuate fasciculus and other tract bundles by DTI could be a useful tool for language location testing in the preoperative study of patients with refractory epilepsy.
Collapse
Affiliation(s)
| | | | | | | | - Guillermo Blasco
- 4Department of Neurosurgery, University Hospital La Princesa, Madrid
| | | | | | - Paloma Pulido
- 4Department of Neurosurgery, University Hospital La Princesa, Madrid
| | - Rafael G Sola
- 5Department of Innovation in Neurosurgery, Universidad Autonoma de Madrid; and.,6Department of Neurosurgery, Hospital del Rosario, Madrid, Spain
| | - Cristina V Torres
- 4Department of Neurosurgery, University Hospital La Princesa, Madrid
| |
Collapse
|
9
|
Chen CL, Shih YC, Liou HH, Hsu YC, Lin FH, Tseng WYI. Premature white matter aging in patients with right mesial temporal lobe epilepsy: A machine learning approach based on diffusion MRI data. NEUROIMAGE-CLINICAL 2019; 24:102033. [PMID: 31795060 PMCID: PMC6978225 DOI: 10.1016/j.nicl.2019.102033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 09/17/2019] [Accepted: 09/21/2019] [Indexed: 01/24/2023]
Abstract
A brain age prediction model was developed based on diffusion MRI data. Patients with right MTLE exhibited older brain age than those with left MTLE. Predicted age difference (PAD) was correlated with seizure frequency in right MTLE. Right uncinate fasciculus had highest contribution to the observed PAD in right MTLE.
Brain age prediction based on machine learning has been applied to various neurological diseases to discover its clinical values. By this innovative approach, it has been reported that the patients with refractory epilepsy had premature brain aging. Of refractory epilepsy, right and left subtypes of mesial temporal lobe epilepsy (MTLE) are the most common forms and exhibit distinct patterns in white matter alterations. So far, it is unclear whether these two subtypes of MTLE would have difference in white matter aging due to distinct white matter alterations. To address this issue, a machine learning based brain age model using diffusion MRI data was established to investigate biological age of white matter tracts. All diffusion MRI datasets were obtained from the same 3-Tesla MRI scanner. To build the brain age prediction model, diffusion MRI datasets of 300 healthy participants were processed to extract age-relevant diffusion indices from 76 major white matter tracts. The extracted diffusion indices underwent Gaussian process regression to build the prediction model for white matter brain age. The model was validated in an independent testing set (N = 40) to ensure no overfitting of the model. The model was then applied to patients with right and left MTLE and matched controls (right MTLE: N = 17, left MTLE: N = 18, controls: N = 37), and predicted age difference (PAD) was obtained by calculating the difference between each individual's predicted brain age and chronological age. The higher PAD score indicated older brain age. The results showed that right MTLE exhibited older predicted brain age than the other two groups (PAD of right MTLE = 10.9 years [p < 0.05 against left MTLE; p < 0.001 against control]; PAD of left MTLE = 2.2 years [p > 0.1 against control]; PAD of controls = 0.82 years). Patients with right and left MTLE showed strong correlations of the PAD scores with age of onset and duration of illness, but both groups showed opposite directions of correlations. In right MTLE, positive correlation of PAD with seizure frequency was found, and the right uncinate fasciculus was the most attributable tract to the increase in PAD. In conclusion, the present study found that patients with right MTLE exhibited premature white matter brain aging and their PAD scores were correlated with seizure frequency. Therefore, PAD is a potentially useful indicator of white matter impairment and disease severity in patients with right MTLE.
Collapse
Affiliation(s)
- Chang-Le Chen
- Institute of Medical Device and Imaging, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yao-Chia Shih
- Institute of Medical Device and Imaging, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Horng-Huei Liou
- Department of Neurology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | | | - Fa-Hsuan Lin
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
| | - Wen-Yih Isaac Tseng
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Medical Imaging, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan.
| |
Collapse
|
10
|
García-Pallero MA, Hodaie M, Zhong J, Manzanares-Soler R, Navas M, Pastor J, Vega-Zelaya L, Delgado-Fernández J, Sola RG, Torres CV. Prediction of Laterality in Temporal Lobe Epilepsy Using White Matter Diffusion Metrics. World Neurosurg 2019; 128:e700-e708. [DOI: 10.1016/j.wneu.2019.04.238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 11/16/2022]
|
11
|
White matter asymmetries in human situs inversus totalis. Brain Struct Funct 2019; 224:2559-2565. [DOI: 10.1007/s00429-019-01904-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/06/2019] [Indexed: 12/15/2022]
|
12
|
Nomi JS, Marshall E, Zaidel E, Biswal B, Castellanos FX, Dick AS, Uddin LQ, Mooshagian E. Diffusion weighted imaging evidence of extra-callosal pathways for interhemispheric communication after complete commissurotomy. Brain Struct Funct 2019; 224:1897-1909. [PMID: 31062161 DOI: 10.1007/s00429-019-01864-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 03/20/2019] [Indexed: 01/10/2023]
Abstract
The integrity of white matter architecture in the human brain is related to cognitive processing abilities. The corpus callosum is the largest white matter bundle interconnecting the two cerebral hemispheres. "Split-brain" patients in whom all cortical commissures have been severed to alleviate intractable epilepsy demonstrate remarkably intact cognitive abilities despite the lack of this important interhemispheric pathway. While it has often been speculated that there are compensatory alterations in the remaining interhemispheric fibers in split-brain patients several years post-commissurotomy, this has never been directly shown. Here we examined extra-callosal pathways for interhemispheric communication in the brain of a patient who underwent complete cerebral commissurotomy using diffusion weighted imaging tractography. We found that compared with a healthy age-matched comparison group, the split-brain patient exhibited increased fractional anisotropy (FA) of the dorsal and ventral pontine decussations of the cortico-cerebellar interhemispheric pathways. Few differences were observed between the patient and the comparison group with respect to FA of other long-range intrahemispheric fibers. These results point to specific cerebellar anatomical substrates that may account for the spared interhemispheric coordination and intact cognitive abilities that have been extensively documented in this unique patient.
Collapse
Affiliation(s)
- Jason S Nomi
- Department of Psychology, University of Miami, P.O. Box 248185-0751, Coral Gables, FL, 33124, USA.
| | - Emily Marshall
- Department of Psychology, University of Miami, P.O. Box 248185-0751, Coral Gables, FL, 33124, USA
| | - Eran Zaidel
- Department of Psychology, University of California, Los Angeles, CA, 90095, USA.,Brain Research Institute, University of California, Los Angeles, CA, 90095, USA
| | - Bharat Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - F Xavier Castellanos
- Department of Child and Adolescent Psychiatry, Hassenfeld Children's Hospital at NYU Langone, New York, NY, 10016, USA.,Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA
| | - Anthony Steven Dick
- Department of Psychology, Florida International University, Miami, FL, 33199, USA
| | - Lucina Q Uddin
- Department of Psychology, University of Miami, P.O. Box 248185-0751, Coral Gables, FL, 33124, USA. .,Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
| | - Eric Mooshagian
- Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO, 63110, USA
| |
Collapse
|
13
|
Age-related changes of white matter association tracts in normal children throughout adulthood: a diffusion tensor tractography study. Neuroradiology 2017; 59:715-724. [PMID: 28580531 DOI: 10.1007/s00234-017-1858-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/22/2017] [Indexed: 12/22/2022]
Abstract
PURPOSE The aim of this study is to study the age, gender and lateral asymmetry-related white matter changes of long association tracts throughout late childhood and adolescence into adulthood using diffusion tensor tractography (DTT). METHODS DTT was performed in 44 healthy subjects aged 7-45 years. Fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD), Trace, density and volume were calculated for long association tracts, namely the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), uncinate fasciculus, superior longitudinal fasciculus (SLF) and its arcuate fibres. FA and diffusivity indices were correlated as function of age using Pearson correlation test. Comparison between males and females, and comparison between both hemispheres among all participants were also performed. A p value less than .01 was considered significant. RESULTS The majority of the examined tracts (SLF and IFOF of both hemispheres, and the arcuate fasciculus, uncinate fasciculus, and ILF of the left hemisphere) followed a common pattern of metric changes with age. This pattern was characterized by significant FA increase accompanied by reduction in RD, Trace without significant AD changes. The right arcuate fasciculus showed similar pattern but without significant FA changes. The right uncinate and right ILF fasciculus demonstrated significant reduction in RD, Trace and AD, with and without significant FA increase, respectively. Left hemispheric dominance regarding the FA and diffusivity indices was demonstrated in uncinate fasciculus with no significant gender-related differences. CONCLUSION Significant microstructural tract-specific maturation processes continue throughout late childhood into adulthood. These processes may represent stages in a cascade of age-related maturation in white matter microstructure.
Collapse
|
14
|
Kreilkamp BA, Weber B, Richardson MP, Keller SS. Automated tractography in patients with temporal lobe epilepsy using TRActs Constrained by UnderLying Anatomy (TRACULA). Neuroimage Clin 2017; 14:67-76. [PMID: 28138428 PMCID: PMC5257189 DOI: 10.1016/j.nicl.2017.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/06/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022]
Abstract
PURPOSE A detailed understanding of white matter tract alterations in patients with temporal lobe epilepsy (TLE) is important as it may provide useful information for likely side of seizure onset, cognitive impairment and postoperative prognosis. However, most diffusion-tensor imaging (DTI) studies have relied on manual reconstruction of tract bundles, despite the recent development of automated techniques. In the present study, we used an automated white matter tractography analysis approach to quantify temporal lobe white matter tract alterations in TLE and determine the relationships between tract alterations, the extent of hippocampal atrophy and the chronicity and severity of the disorder. METHODS We acquired preoperative T1-weighted and DTI data in 64 patients with well-characterized TLE, with imaging and histopathological evidence of hippocampal sclerosis. Identical acquisitions were collected for 44 age- and sex-matched healthy controls. We employed automatic probabilistic tractography DTI analysis using TRActs Constrained by UnderLying Anatomy (TRACULA) available in context of Freesurfer software for the reconstruction of major temporal lobe tract bundles. We determined the factors influencing probabilistic tract reconstruction and investigated alterations of DTI scalar metrics along white matter tracts with respect to hippocampal volume, which was automatically estimated using Freesurfer's morphometric pipelines. We also explored the relationships between white matter tract alterations and duration of epilepsy, age of onset of epilepsy and seizure burden (defined as a function of seizure frequency and duration of epilepsy). RESULTS Whole-tract diffusion characteristics of patients with TLE differed according to side of epilepsy and were significantly different between patients and controls. Waypoint comparisons along each tract revealed that patients had significantly altered tissue characteristics of the ipsilateral inferior-longitudinal, uncinate fasciculus, superior longitudinal fasciculus and cingulum relative to controls. Changes were more widespread (ipsilaterally and contralaterally) in patients with left TLE while patients with right TLE showed changes that remained spatially confined in ipsilateral tract regions. We found no relationship between DTI alterations and volume of the epileptogenic hippocampus. DTI alterations of anterior ipsilateral uncinate and inferior-longitudinal fasciculus correlated with duration of epilepsy (over and above effects of age) and age at onset of epilepsy. Seizure burden correlated with tissue characteristics of the uncinate fasciculus. CONCLUSION This study shows that TRACULA permits the detection of alterations of DTI tract scalar metrics in patients with TLE. It also provides the opportunity to explore relationships with structural volume measurements and clinical variables along white matter tracts. Our data suggests that the anterior temporal lobe portions of the uncinate and inferior-longitudinal fasciculus may be particularly vulnerable to pathological alterations in patients with TLE. These alterations are unrelated to the extent of hippocampal atrophy (and therefore potentially mediated by independent mechanisms) but influenced by chronicity and severity of the disorder.
Collapse
Affiliation(s)
- Barbara A.K. Kreilkamp
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, UK
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Bernd Weber
- Department of Epileptology, University of Bonn, Germany
- Department of NeuroCognition/Imaging, Life&Brain Research Center, Bonn, Germany
| | - Mark P. Richardson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Simon S. Keller
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, UK
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| |
Collapse
|
15
|
Slinger G, Sinke MRT, Braun KPJ, Otte WM. White matter abnormalities at a regional and voxel level in focal and generalized epilepsy: A systematic review and meta-analysis. NEUROIMAGE-CLINICAL 2016; 12:902-909. [PMID: 27882296 PMCID: PMC5114611 DOI: 10.1016/j.nicl.2016.10.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 10/25/2016] [Accepted: 10/31/2016] [Indexed: 12/24/2022]
Abstract
Objective Since the introduction of diffusion tensor imaging, white matter abnormalities in epilepsy have been studied extensively. However, the affected areas reported, the extent of abnormalities and the association with relevant clinical parameters are highly variable. We aimed to obtain a more consistent estimate of white matter abnormalities and their association with clinical parameters in different epilepsy types. Methods We systematically searched for differences in white matter fractional anisotropy and mean diffusivity, at regional and voxel level, between people with epilepsy and healthy controls. Meta-analyses were used to quantify the directionality and extent of these differences. Correlations between white matter differences and age of epilepsy onset, duration of epilepsy and sex were assessed with meta-regressions. Results Forty-two studies, with 1027 people with epilepsy and 1122 controls, were included with regional data. Sixteen voxel-based studies were also included. People with temporal or frontal lobe epilepsy had significantly decreased fractional anisotropy (Δ –0.021, 95% confidence interval –0.026 to –0.016) and increased mean diffusivity (Δ0.026 × 10–3 mm2/s, 0.012 to 0.039) in the commissural, association and projection white matter fibers. White matter was much less affected in generalized epilepsy. White matter changes in people with focal epilepsy correlated with age at onset, epilepsy duration and sex. Significance This study provides a better estimation of white matter changes in different epilepsies. Effects are particularly found in people with focal epilepsy. Correlations with the duration of focal epilepsy support the hypothesis that these changes are, at least partly, a consequence of seizures and may warrant early surgery. Future studies need to guarantee adequate group sizes, as white matter differences in epilepsy are small. White matter FA and MD are more affected in focal than in generalized epilepsy. Epilepsy subtypes show distinct patterns of affected white matter regions. White matter integrity is altered both ipsi- and contralaterally in focal epilepsy. White matter changes in focal epilepsy seem to be a consequence of seizures.
Collapse
Affiliation(s)
- Geertruida Slinger
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands
| | - Michel R T Sinke
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands
| | - Kees P J Braun
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Willem M Otte
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands; Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| |
Collapse
|
16
|
Hau J, Sarubbo S, Houde JC, Corsini F, Girard G, Deledalle C, Crivello F, Zago L, Mellet E, Jobard G, Joliot M, Mazoyer B, Tzourio-Mazoyer N, Descoteaux M, Petit L. Revisiting the human uncinate fasciculus, its subcomponents and asymmetries with stem-based tractography and microdissection validation. Brain Struct Funct 2016; 222:1645-1662. [PMID: 27581617 DOI: 10.1007/s00429-016-1298-6] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 08/22/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Janice Hau
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Silvio Sarubbo
- Division of Neurosurgery, Department of Neurosciences, "S. Chiara" Hospital, Trento APSS, Trento, Italy
- Structural and Functional Connectivity Lab, Division of Neurosurgery, "S. Chiara" Hospital, Trento APSS, Trento, Italy
| | | | - Francesco Corsini
- Division of Neurosurgery, Department of Neurosciences, "S. Chiara" Hospital, Trento APSS, Trento, Italy
- Structural and Functional Connectivity Lab, Division of Neurosurgery, "S. Chiara" Hospital, Trento APSS, Trento, Italy
| | - Gabriel Girard
- Sherbrooke Connectivity Imaging Lab, University of Sherbrooke, Sherbrooke, Canada
| | - Charles Deledalle
- Institut de Mathématiques de Bordeaux-UMR 5251, CNRS, Talence, France
| | - Fabrice Crivello
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Laure Zago
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Emmanuel Mellet
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Gaël Jobard
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Marc Joliot
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Bernard Mazoyer
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Nathalie Tzourio-Mazoyer
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France
| | - Maxime Descoteaux
- Sherbrooke Connectivity Imaging Lab, University of Sherbrooke, Sherbrooke, Canada
| | - Laurent Petit
- Groupe d'Imagerie Neurofonctionnelle, Institut des Maladies Neurodégénératives-UMR 5293, CNRS, CEA, University of Bordeaux, PAC Carreire, 146 rue Léo Saignat-CS61292-Case 28, 33076, Bordeaux, France.
| |
Collapse
|
17
|
Nagy SA, Horváth R, Perlaki G, Orsi G, Barsi P, John F, Horváth A, Kovács N, Bogner P, Ábrahám H, Bóné B, Gyimesi C, Dóczi T, Janszky J. Age at onset and seizure frequency affect white matter diffusion coefficient in patients with mesial temporal lobe epilepsy. Epilepsy Behav 2016; 61:14-20. [PMID: 27232377 DOI: 10.1016/j.yebeh.2016.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 02/01/2023]
Abstract
In mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), structural abnormalities are present not only in the hippocampus but also in the white matter with ipsilateral predominance. Although the timing of epilepsy onset is commonly associated with clinical and semiological dissimilarities, limited data exist regarding white matter diffusion changes with respect to age at epilepsy onset. The aim of this study was to investigate diffusion changes in the white matter of patients with unilateral MTLE-HS with respect to clinical parameters and to compare them with an age- and sex-matched healthy control group. Apparent diffusion coefficients (ADCs) were derived using monoexponential approaches from 22 (11 early and 11 late age at onset) patients with unilateral MTLE-HS and 22 age- and sex-matched control subjects after acquiring diffusion-weighted images on a 3T MRI system. Data were analyzed using two-tailed t-tests and multiple linear regression models. In the group with early onset MTLE-HS, ADC was significantly elevated in the ipsilateral hemispheric (p=0.04) and temporal lobe white matter (p=0.01) compared with that in controls. These differences were not detectable in late onset MTLE-HS patients. Apparent diffusion coefficient of the group with early onset MTLE-HS was negatively related to age at epilepsy onset in the ipsilateral hemispheric white matter (p=0.03) and the uncinate fasciculus (p=0.03), while in patients with late onset MTLE-HS, ADC was no longer dependent on age at epilepsy onset itself but rather on the seizure frequency in the ipsilateral uncinate fasciculus (p=0.03). Such diffusivity pattern has been associated with chronic white matter degeneration, reflecting myelin loss and higher extracellular volume which are more pronounced in the frontotemporal regions and also depend on clinical features. In the group with early onset MTLE-HS, the timing of epilepsy seems to be the major cause of white matter abnormalities while in late onset disease, it has a secondary role in provoking diffusion changes.
Collapse
Affiliation(s)
- Szilvia A Nagy
- Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Neurobiology of Stress Research Group, H-7624 Pécs, Ifjúság Street 20., Hungary.
| | - Réka Horváth
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - Gábor Perlaki
- Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary.
| | - Gergely Orsi
- Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary.
| | - Péter Barsi
- MR Research Centre, Semmelweis University, H-1083 Budapest, Balassa Street 6., Hungary.
| | - Flóra John
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - Andrea Horváth
- Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; Department of Neurosurgery, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - Norbert Kovács
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary.
| | - Péter Bogner
- Department of Radiology, University of Pécs, H-7624 Pécs, Ifjúság Street 13., Hungary.
| | - Hajnalka Ábrahám
- Department of Medical Biology, University of Pécs, H-7624 Pécs, Szigeti Street 12., Hungary; Central Electron Microscopic Laboratory, University of Pécs, H-7624 Pécs, Honvéd Street 1., Hungary.
| | - Beáta Bóné
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - Csilla Gyimesi
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - Tamás Dóczi
- Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary; Department of Neurosurgery, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary.
| | - József Janszky
- Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary.
| |
Collapse
|
18
|
Nazem-Zadeh MR, Bowyer SM, Moran JE, Davoodi-Bojd E, Zillgitt A, Weiland BJ, Bagher-Ebadian H, Mahmoudi F, Elisevich K, Soltanian-Zadeh H. MEG Coherence and DTI Connectivity in mTLE. Brain Topogr 2016; 29:598-622. [PMID: 27060092 PMCID: PMC5542022 DOI: 10.1007/s10548-016-0488-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/04/2016] [Indexed: 12/11/2022]
Abstract
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). Resting state MEG data was analyzed using MEG coherence source imaging (MEG-CSI) method to determine the coherence in 54 anatomical sites in 17 adult mTLE patients with surgical resection and Engel class I outcome, and 17 age- and gender- matched controls. DTI tractography identified the fiber tracts passing through these same anatomical sites of the same subjects. Then, DTI nodal degree and laterality index were calculated and compared with the corresponding MEG coherence and laterality index. MEG coherence laterality, after Bonferroni adjustment, showed significant differences for right versus left mTLE in insular cortex and both lateral orbitofrontal and superior temporal gyri (p < 0.017). Likewise, DTI nodal degree laterality, after Bonferroni adjustment, showed significant differences for right versus left mTLE in gyrus rectus, insular cortex, precuneus and superior temporal gyrus (p < 0.017). In insular cortex, MEG coherence laterality correlated with DTI nodal degree laterality ([Formula: see text] in the cases of mTLE. None of these anatomical sites showed statistically significant differences in coherence laterality between right and left sides of the controls. Coherence laterality was in agreement with the declared side of epileptogenicity in insular cortex (in 82 % of patients) and both lateral orbitofrontal (88 %) and superior temporal gyri (88 %). Nodal degree laterality was also in agreement with the declared side of epileptogenicity in gyrus rectus (in 88 % of patients), insular cortex (71 %), precuneus (82 %) and superior temporal gyrus (94 %). Combining all significant laterality indices improved the lateralization accuracy to 94 % and 100 % for the coherence and nodal degree laterality indices, respectively. The associated variations in diffusion properties of fiber tracts quantified by DTI and coherence measures quantified by MEG with respect to epileptogenicity possibly reflect the chronic microstructural cerebral changes associated with functional interictal activity. The proposed methodology for using MEG and DTI to investigate diffusion abnormalities related to focal epileptogenicity and propagation may provide a further means of noninvasive lateralization.
Collapse
Affiliation(s)
| | - Susan M. Bowyer
- Neurology, Henry Ford Health System, Detroit, MI, 48202, USA
| | - John E. Moran
- Neurology, Henry Ford Health System, Detroit, MI, 48202, USA
| | | | - Andrew Zillgitt
- Neurology, Henry Ford Health System, Detroit, MI, 48202, USA
| | - Barbara J. Weiland
- Institute of Cognitive Science University of Colorado Boulder, Boulder, CO, 80309 USA,
| | - Hassan Bagher-Ebadian
- Research Administration, Henry Ford Health System, Detroit, MI, 48202, USA
- Radiation Oncology Departments, Henry Ford Health System, Detroit, MI, 48202, USA
| | - Fariborz Mahmoudi
- Research Administration, Henry Ford Health System, Detroit, MI, 48202, USA
- Computer and IT engineering Faculty, Islamic Azad University, Qazvin Branch, Iran
| | - Kost Elisevich
- Department of Clinical Neurosciences, Spectrum Health System, Division of Neurosurgery, Michigan State University, Grand Rapids, MI, 49503, USA,
| | - Hamid Soltanian-Zadeh
- Research Administration, Henry Ford Health System, Detroit, MI, 48202, USA
- Control and Intelligent Processing Center of Excellence (CIPCE), School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran,
| |
Collapse
|
19
|
The uncinate fasciculus as observed using diffusion spectrum imaging in the human brain. Neuroradiology 2016; 58:595-606. [DOI: 10.1007/s00234-016-1650-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/12/2016] [Indexed: 10/22/2022]
|
20
|
Chiang S, Levin HS, Wilde E, Haneef Z. White matter structural connectivity changes correlate with epilepsy duration in temporal lobe epilepsy. Epilepsy Res 2015; 120:37-46. [PMID: 26709881 DOI: 10.1016/j.eplepsyres.2015.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 10/29/2015] [Accepted: 12/04/2015] [Indexed: 11/27/2022]
Abstract
PURPOSE Temporal lobe epilepsy (TLE) is thought to be a network disease and structural changes using diffusion tensor imaging (DTI) have been shown. However, lateralized differences in the structural integrity of TLE, as well as changes in structural integrity with longer disease duration, have not been well defined. METHODS We examined the fractional anisotropy (FA) and mean diffusivity (MD) in the hippocampus, as well as its primary (cingulum and fornix) and remote (uncinate and external capsule) connections in both right and left TLE. Changes in diffusion measures over the disease course were examined by correlating FA and MD in the various structures with epilepsy duration. The potential for each measure of anisotropy and diffusivity as a marker of TLE laterality was investigated using random forest (RF) analysis. RESULTS MD was increased in the bilateral hippocampus, cingulum, fornix and the right external capsule in both left and right TLE compared to controls. In addition, left TLE exhibited an increased MD in the ipsilateral uncinate fasciculus and bilateral external capsules. A decrease in FA was seen in the left cingulum in left TLE. RF analysis demonstrated that MD of the right hippocampus and FA of the left external capsule were important predictors of TLE laterality. An association of increased MD with epilepsy duration was seen in the left hippocampus in left TLE. CONCLUSION Evidence of disrupted white matter architecture in the hippocampus and its primary and remote connections were demonstrated in TLE. While changes in the hippocampus and cingulum were more prominent in right TLE, remote changes were more prominent in left TLE. MD of the right hippocampus and FA of the left external capsule were found to be the strongest structural predictors of TLE laterality. Changes associated with duration of epilepsy indicated that changes in structural integrity may be progressive over the disease course. This study illustrates the potential of structural diffusion tensor imaging in elucidating pathophysiology, enhancing diagnosis and assisting prognostication.
Collapse
Affiliation(s)
- Sharon Chiang
- Department of Statistics, Rice University, Houston, TX, United States.
| | - Harvey S Levin
- Department of Physical Medicine, Baylor College of Medicine, Houston, TX, United States; Michael E. De Bakey Veterans Affairs Medical Center, Houston, TX, United States.
| | - Elisabeth Wilde
- Department of Physical Medicine, Baylor College of Medicine, Houston, TX, United States.
| | - Zulfi Haneef
- Department of Neurology, Baylor College of Medicine, Houston, TX, United States; Neurology Care Line, Michael E. DeBakey VA Medical Center, Houston, TX, United States.
| |
Collapse
|
21
|
Diffusion MRI properties of the human uncinate fasciculus correlate with the ability to learn visual associations. Cortex 2015; 72:65-78. [DOI: 10.1016/j.cortex.2015.01.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/25/2014] [Accepted: 01/29/2015] [Indexed: 01/14/2023]
|
22
|
Nazem-Zadeh MR, Elisevich K, Air EL, Schwalb JM, Divine G, Kaur M, Wasade VS, Mahmoudi F, Shokri S, Bagher-Ebadian H, Soltanian-Zadeh H. DTI-based response-driven modeling of mTLE laterality. NEUROIMAGE-CLINICAL 2015; 11:694-706. [PMID: 27330966 PMCID: PMC4900487 DOI: 10.1016/j.nicl.2015.10.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 10/25/2015] [Accepted: 10/27/2015] [Indexed: 12/30/2022]
Abstract
Purpose To develop lateralization models for distinguishing between unilateral and bilateral mesial temporal lobe epilepsy (mTLE) and determining laterality in cases of unilateral mTLE. Background mTLE is the most common form of medically refractory focal epilepsy. Many mTLE patients fail to demonstrate an unambiguous unilateral ictal onset. Intracranial EEG (icEEG) monitoring can be performed to establish whether the ictal origin is unilateral or truly bilateral with independent bitemporal ictal origin. However, because of the expense and risk of intracranial electrode placement, much research has been done to determine if the need for icEEG can be obviated with noninvasive neuroimaging methods, such as diffusion tensor imaging (DTI). Methods Fractional anisotropy (FA) was used to quantify microstructural changes reflected in the diffusivity properties of the corpus callosum, cingulum, and fornix, in a retrospective cohort of 31 patients confirmed to have unilateral (n = 24) or bilateral (n = 7) mTLE. All unilateral mTLE patients underwent resection with an Engel class I outcome. Eleven were reported to have hippocampal sclerosis on pathological analysis; nine had undergone prior icEEG. The bilateral mTLE patients had undergone icEEG demonstrating independent epileptiform activity in both right and left hemispheres. Twenty-three nonepileptic subjects were included as controls. Results In cases of right mTLE, FA showed significant differences from control in all callosal subregions, in both left and right superior cingulate subregions, and in forniceal crura. Comparison of right and left mTLE cases showed significant differences in FA of callosal genu, rostral body, and splenium and the right posteroinferior and superior cingulate subregions. In cases of left mTLE, FA showed significant differences from control only in the callosal isthmus. Significant differences in FA were identified when cases of right mTLE were compared with bilateral mTLE cases in the rostral and midbody callosal subregions and isthmus. Based on 11 FA measurements in the cingulate, callosal and forniceal subregions, a response-driven lateralization model successfully differentiated all cases (n = 54) into groups of unilateral right (n = 12), unilateral left (n = 12), and bilateral mTLE (n = 7), and nonepileptic control (23). Conclusion The proposed response-driven DTI biomarker is intended to lessen diagnostic ambiguity of laterality in cases of mTLE and help optimize selection of surgical candidates. Application of this model shows promise in reducing the need for invasive icEEG in prospective cases. Develop response-driven lateralization model using diffusion tensor imaging Distinguish between unilateral and bilateral mesial temporal lobe epilepsy (mTLE) Determine or lessen diagnostic ambiguity of laterality in cases of unilateral mTLE Optimize selection of surgical candidates Reduction of the need for intracranial EEG
Collapse
Affiliation(s)
| | - Kost Elisevich
- Department of Clinical Neurosciences, Spectrum Health Medical Group, Division of Neurosurgery, Michigan State University, Grand Rapids, MI 49503, USA
| | - Ellen L Air
- Neurosurgery Department, Henry Ford Health System, Detroit, MI 48202, USA.
| | - Jason M Schwalb
- Neurosurgery Department, Henry Ford Health System, Detroit, MI 48202, USA.
| | - George Divine
- Public Health Sciences Department, Henry Ford Health System, Detroit, MI 48202, USA.
| | - Manpreet Kaur
- Neurosurgery Department, Henry Ford Health System, Detroit, MI 48202, USA.
| | | | - Fariborz Mahmoudi
- Radiology and Research Administration Department, Henry Ford Health System, Detroit, MI 48202, USA; Computer and IT engineering Faculty, Islamic Azad University, Qazvin Branch, Iran.
| | - Saeed Shokri
- Radiology and Research Administration Department, Henry Ford Health System, Detroit, MI 48202, USA; School of Computer Science, Wayne State University, Detroit, MI 48202, USA.
| | - Hassan Bagher-Ebadian
- Radiology and Research Administration Department, Henry Ford Health System, Detroit, MI 48202, USA; Neurology Department, Henry Ford Health System, Detroit, MI 48202, USA.
| | - Hamid Soltanian-Zadeh
- Radiology and Research Administration Department, Henry Ford Health System, Detroit, MI 48202, USA; Control and Intelligent Processing Center of Excellence (CIPCE), School of Electrical and Computer, University of Tehran, Tehran, Iran.
| |
Collapse
|
23
|
Bernhardt BC, Bonilha L, Gross DW. Network analysis for a network disorder: The emerging role of graph theory in the study of epilepsy. Epilepsy Behav 2015; 50:162-70. [PMID: 26159729 DOI: 10.1016/j.yebeh.2015.06.005] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 01/01/2023]
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 substrate of TLE is not limited to the hippocampus alone, but rather is broadly distributed across multiple brain regions and interconnecting white matter pathways. We will introduce basic concepts of graph theory, a formalism to quantify topological properties of complex systems that has recently been widely applied to study networks derived from brain imaging and electrophysiology. We will discuss converging graph theoretical evidence indicating that networks in TLE show marked shifts in their overall topology, providing insight into the neurobiology of TLE as a network-level disorder. Our review will conclude by discussing methodological challenges and future clinical applications of this powerful analytical approach.
Collapse
Affiliation(s)
- Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada; Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
| | - Leonardo Bonilha
- Department of Neurology, Medical University of South Carolina, SC, USA
| | - Donald W Gross
- Division of Neurology, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
24
|
Development of the uncinate fasciculus: Implications for theory and developmental disorders. Dev Cogn Neurosci 2015; 14:50-61. [PMID: 26143154 PMCID: PMC4795006 DOI: 10.1016/j.dcn.2015.06.003] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/29/2015] [Accepted: 06/18/2015] [Indexed: 12/27/2022] Open
Abstract
The uncinate fasciculus (UF) is a long-range white matter tract that connects limbic regions in the temporal lobe to the frontal lobe. The UF is one of the latest developing tracts, and continues maturing into the third decade of life. As such, individual differences in the maturational profile of the UF may serve to explain differences in behavior. Indeed, atypical macrostructure and microstructure of the UF have been reported in numerous studies of individuals with developmental and psychiatric disorders such as social deprivation and maltreatment, autism spectrum disorders, conduct disorder, risk taking, and substance abuse. The present review evaluates what we currently know about the UF's developmental trajectory and reviews the literature relating UF abnormalities to specific disorders. Additionally, we take a dimensional approach and critically examine symptoms and behavioral impairments that have been demonstrated to cluster with UF aberrations, in an effort to relate these impairments to our speculations regarding the functionality of the UF. We suggest that developmental disorders with core problems relating to memory retrieval, reward and valuation computation, and impulsive decision making may be linked to aberrations in uncinate microstructure.
Collapse
|
25
|
Abnormalities of the uncinate fasciculus correlate with executive dysfunction in patients with left temporal lobe epilepsy. Magn Reson Imaging 2015; 33:544-50. [DOI: 10.1016/j.mri.2015.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 02/12/2015] [Accepted: 02/15/2015] [Indexed: 11/18/2022]
|
26
|
Campos BM, Coan AC, Beltramini GC, Liu M, Yassuda CL, Ghizoni E, Beaulieu C, Gross DW, Cendes F. White matter abnormalities associate with type and localization of focal epileptogenic lesions. Epilepsia 2014; 56:125-32. [PMID: 25545559 DOI: 10.1111/epi.12871] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2014] [Indexed: 11/29/2022]
Abstract
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. We performed fiber-tractography using a semiautomatic deterministic method to yield average fractional anisotropy (FA), axial (AD), and radial (RD) diffusivity ipsilateral and contralateral to the epileptogenic zone of the following tracts based on their functional and anatomic relevance: body of fornix (BoF), body of cingulum (BoC), inferior frontal occipital (IFO), and uncinate fasciculi (UF). In addition, we performed VBM of the WM maps to assess macrostructural integrity differences among groups. RESULTS TLE-HS had ipsilateral and contralateral decreased FA and increased RD for all tracts. VBM showed WM alterations mainly in the ipsilateral parahippocampal region and contralateral superior temporal gyrus. FLE-FCD showed bilateral FA decreases only in the BoC and ipsilateral RD increases also in the BoC. VBM showed WM reduction mainly in the ipsilateral precuneus and posterior and anterior cingulum. No significant WM alterations were found in the TLE-NL in DTI or VBM analysis. SIGNIFICANCE WM abnormalities differ in distinct AED-resistant localization-related epilepsies. The diverse distribution of the WM damage in these patients suggests that the localization of the epileptic networks may play a role in the WM burden. However, the distinct degree of this damage, more accentuated in TLE-HS, also suggests that the underlying cause of the epilepsy is probably an additional factor to explain this WM damage.
Collapse
Affiliation(s)
- Brunno M Campos
- Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Caciagli L, Bernhardt BC, Hong SJ, Bernasconi A, Bernasconi N. Functional network alterations and their structural substrate in drug-resistant epilepsy. Front Neurosci 2014; 8:411. [PMID: 25565942 PMCID: PMC4263093 DOI: 10.3389/fnins.2014.00411] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/24/2014] [Indexed: 12/24/2022] Open
Abstract
The advent of MRI has revolutionized the evaluation and management of drug-resistant epilepsy by allowing the detection of the lesion associated with the region that gives rise to seizures. Recent evidence indicates marked chronic alterations in the functional organization of lesional tissue and large-scale cortico-subcortical networks. In this review, we focus on recent methodological developments in functional MRI (fMRI) analysis techniques and their application to the two most common drug-resistant focal epilepsies, i.e., temporal lobe epilepsy related to mesial temporal sclerosis and extra-temporal lobe epilepsy related to focal cortical dysplasia. We put particular emphasis on methodological developments in the analysis of task-free or “resting-state” fMRI to probe the integrity of intrinsic networks on a regional, inter-regional, and connectome-wide level. In temporal lobe epilepsy, these techniques have revealed disrupted connectivity of the ipsilateral mesiotemporal lobe, together with contralateral compensatory reorganization and striking reconfigurations of large-scale networks. In cortical dysplasia, initial observations indicate functional alterations in lesional, peri-lesional, and remote neocortical regions. While future research is needed to critically evaluate the reliability, sensitivity, and specificity, fMRI mapping promises to lend distinct biomarkers for diagnosis, presurgical planning, and outcome prediction.
Collapse
Affiliation(s)
- Lorenzo Caciagli
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Seok-Jun Hong
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| |
Collapse
|
28
|
Chaudhary UJ, Duncan JS. Applications of blood-oxygen-level-dependent functional magnetic resonance imaging and diffusion tensor imaging in epilepsy. Neuroimaging Clin N Am 2014; 24:671-94. [PMID: 25441507 DOI: 10.1016/j.nic.2014.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The lifetime prevalence of epilepsy ranges from 2.7 to 12.4 per 1000 in Western countries. Around 30% of patients with epilepsy remain refractory to antiepileptic drugs and continue to have seizures. Noninvasive imaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) have helped to better understand mechanisms of seizure generation and propagation, and to localize epileptic, eloquent, and cognitive networks. In this review, the clinical applications of fMRI and DTI are discussed, for mapping cognitive and epileptic networks and organization of white matter tracts in individuals with epilepsy.
Collapse
Affiliation(s)
- Umair J Chaudhary
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK.
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK; Queen Square Division, UCLH NHS Foundation Trust, Queen Square, London WC1N 3BG, UK
| |
Collapse
|
29
|
Pustina D, Doucet G, Sperling M, Sharan A, Tracy J. Increased microstructural white matter correlations in left, but not right, temporal lobe epilepsy. Hum Brain Mapp 2014; 36:85-98. [PMID: 25137314 DOI: 10.1002/hbm.22614] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/04/2014] [Accepted: 08/11/2014] [Indexed: 11/06/2022] Open
Abstract
Microstructural white matter tract correlations have been shown to reflect known patterns of phylogenetic development and functional specialization in healthy subjects. The aim of this study was to establish intertract correlations in a group of controls and to examine potential deviations from normality in temporal lobe epilepsy (TLE). We investigated intertract correlations in 28 healthy controls, 21 left TLE (LTLE) and 23 right TLE (RTLE). Nine tracts were investigated, comprising the parahippocampal fasciculi, the uncinate fasciculi, the arcuate fasciculi, the frontoparietal tracts, and the fornix. An abnormal increase in tract correlations was observed in LTLE, while RTLE showed intertract correlations similar to controls. In the control group, tract correlations increased with increasing fractional anisotropy (FA), while in the TLE groups tract correlations increased with decreasing FA. Cluster analyses revealed agglomeration of bilateral pairs of homologous tracts in healthy subjects, with such pairs separated in our LTLE and RTLE groups. Discriminant analyses aimed at distinguishing LTLE from RTLE, revealing that tract correlations produce higher rates of accurate group classification than FA values. Our results confirm and extend previous work by showing that LTLE compared to RTLE patients display not only more extensive losses in microstructural orientation but also more aberrant intertract correlations. Aberrant correlations may be related to pathologic processes (i.e., seizure spread) or to adaptive processes aimed at preserving key cognitive functions. Our data suggest that tract correlations may have predictive value in distinguishing LTLE from RTLE, potentially moving diffusion imaging to a place of greater prominence in clinical practice.
Collapse
Affiliation(s)
- Dorian Pustina
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | | | | | | | | |
Collapse
|
30
|
Pustina D, Doucet G, Evans J, Sharan A, Sperling M, Skidmore C, Tracy J. Distinct types of white matter changes are observed after anterior temporal lobectomy in epilepsy. PLoS One 2014; 9:e104211. [PMID: 25089698 PMCID: PMC4121328 DOI: 10.1371/journal.pone.0104211] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 07/10/2014] [Indexed: 11/18/2022] Open
Abstract
Anterior temporal lobectomy (ATL) is commonly adopted to control medically intractable temporal lobe epilepsy (TLE). Depending on the side of resection, the degree to which Wallerian degeneration and adaptive plasticity occur after ATL has important implications for understanding cognitive and clinical outcome. We obtained diffusion tensor imaging from 24 TLE patients (12 left) before and after surgery, and 12 matched controls at comparable time intervals. Voxel-based analyses were performed on fractional anisotropy (FA) before and after surgery. Areas with postoperative FA increase were further investigated to distinguish between genuine plasticity and processes related to the degeneration of crossing fibers. Before surgery, both patient groups showed bilateral reduced FA in numerous tracts, but left TLE patients showed more extensive effects, including language tracts in the contralateral hemisphere (superior longitudinal fasciculus and uncinate). After surgery, FA decreased ipsilaterally in both ATL groups, affecting the fornix, uncinate, stria terminalis, and corpus callosum. FA increased ipsilaterally along the superior corona radiata in both left and right ATL groups, exceeding normal FA values. In these clusters, the mode of anisotropy increased as well, confirming fiber degeneration in an area with crossing fibers. In left ATL patients, pre-existing low FA values in right superior longitudinal and uncinate fasciculi normalized after surgery, while MO values did not change. Preoperative verbal fluency correlated with FA values in all areas that later increased FA in left TLE patients, but postoperative verbal fluency correlated only with FA of the right superior longitudinal fasciculus. Our results demonstrate that genuine reorganization occurs in non-dominant language tracts after dominant hemisphere resection, a process that may help implement the inter-hemispheric shift of language activation found in fMRI studies. The results indicate that left TLE patients, despite showing more initial white matter damage, have the potential for greater adaptive changes postoperatively than right TLE patients.
Collapse
Affiliation(s)
- Dorian Pustina
- Thomas Jefferson University, Department of Neurology, Philadelphia, Pennsylvania, United States of America
| | - Gaelle Doucet
- Thomas Jefferson University, Department of Neurology, Philadelphia, Pennsylvania, United States of America
- Thomas Jefferson University, Department of Neurosurgery, Philadelphia, Pennsylvania, United States of America
| | - James Evans
- Thomas Jefferson University, Department of Neurosurgery, Philadelphia, Pennsylvania, United States of America
| | - Ashwini Sharan
- Thomas Jefferson University, Department of Neurosurgery, Philadelphia, Pennsylvania, United States of America
| | - Michael Sperling
- Thomas Jefferson University, Department of Neurology, Philadelphia, Pennsylvania, United States of America
| | - Christopher Skidmore
- Thomas Jefferson University, Department of Neurology, Philadelphia, Pennsylvania, United States of America
| | - Joseph Tracy
- Thomas Jefferson University, Department of Neurology, Philadelphia, Pennsylvania, United States of America
| |
Collapse
|
31
|
Sanfratello L, Caprihan A, Stephen JM, Knoefel JE, Adair JC, Qualls C, Lundy SL, Aine CJ. Same task, different strategies: how brain networks can be influenced by memory strategy. Hum Brain Mapp 2014; 35:5127-40. [PMID: 24931401 DOI: 10.1002/hbm.22538] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/04/2014] [Accepted: 04/15/2014] [Indexed: 11/07/2022] Open
Abstract
Previous functional neuroimaging studies demonstrated that different neural networks underlie different types of cognitive processing by engaging participants in particular tasks, such as verbal or spatial working memory (WM) tasks. However, we report here that even when a WM task is defined as verbal or spatial, different types of memory strategies may be used to complete it, with concomitant variations in brain activity. We developed a questionnaire to characterize the type of strategy used by individual members in a group of 28 young healthy participants (18-25 years) during a spatial WM task. A cluster analysis was performed to differentiate groups. We acquired functional magnetoencephalography and structural diffusion tensor imaging measures to characterize the brain networks associated with the use of different strategies. We found two types of strategies were used during the spatial WM task, a visuospatial and a verbal strategy, and brain regions and time courses of activation differed between participants who used each. Task performance also varied by type of strategy used with verbal strategies showing an advantage. In addition, performance on neuropsychological tests (indices from Wechsler Adult Intelligence Scale-IV, Rey Complex Figure Test) correlated significantly with fractional anisotropy measures for the visuospatial strategy group in white matter tracts implicated in other WM and attention studies. We conclude that differences in memory strategy can have a pronounced effect on the locations and timing of brain activation and that these differences need further investigation as a possible confounding factor for studies using group averaging as a means for summarizing results.
Collapse
Affiliation(s)
- Lori Sanfratello
- Department of Radiology, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Kucukboyaci NE, Kemmotsu N, Leyden KM, Girard HM, Tecoma ES, Iragui VJ, McDonald CR. Integration of multimodal MRI data via PCA to explain language performance. NEUROIMAGE-CLINICAL 2014; 5:197-207. [PMID: 25068109 PMCID: PMC4110349 DOI: 10.1016/j.nicl.2014.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/07/2014] [Accepted: 05/09/2014] [Indexed: 11/16/2022]
Abstract
Objective/methods Neuroimaging research has predominantly focused on exploring how cortical or subcortical brain abnormalities are related to language dysfunction in patients with neurological disease through the use of single modality imaging. Still, limited knowledge exists on how various MRI measures relate to each other and to patients' language performance. In this study, we explored the relationship between measures of regional cortical thickness, gray–white matter contrast (GWMC), white matter diffusivity [mean diffusivity (MD) and fractional anisotropy (FA)] and the relative contributions of these MRI measures to predicting language function across patients with temporal lobe epilepsy (TLE) and healthy controls. T1- and diffusion-weighted MRI data were collected from 56 healthy controls and 52 patients with TLE. By focusing on frontotemporal regions implicated in language function, we reduced each domain of MRI data to its principal component (PC) and quantified the correlations among these PCs and the ability of these PCs to explain the variation in vocabulary, naming and fluency. We followed up our significant findings by assessing the predictive power of the implicated PCs with respect to language impairment in our sample. Results We found significant positive associations between PCs representing cortical thickness, GWMC and FA that appeared to be partially mediated by changes in total brain volume. We also found a significant association between reduced FA and increased MD after controlling for confounding factors (e.g., age, field strength, total brain volume). Reduced FA was significantly associated with reductions in visual naming while increased MD was associated with reductions in auditory naming scores, even after controlling for the variability explained by reductions in hippocampal volumes. Inclusion of FA and MD PCs in predictive models of language impairment resulted in significant improvements in sensitivity and specificity of the predictions. Conclusions Quantitative MRI measures from T1 and diffusion-weighted scans are unlikely to represent perfectly orthogonal vectors of disease in individuals with epilepsy. On the contrary, they exhibit highly intercorrelated PCs in their factor structures, which is consistent with an underlying pathological process that affects both the cortical and the subcortical structures simultaneously. In addition to hippocampal volume, the PCs of diffusion weighted measures (FA and MD) increase the sensitivity and specificity for determining naming impairment in patients with TLE. These findings underline the importance of combining multimodal imaging measures to better predict language performance in TLE that could extend to other patients with prominent language impairments. We integrate structural and diffusion MRI data from TLE patients and controls. We use PCA to characterize disease-related volumetric and tract-based changes. Increased left hemisphere FA is associated with worse visual naming. Decreased left hemisphere MD is associated with worse auditory naming. Using diffusion-based MRI metrics improves prediction of language function in TLE.
Collapse
Affiliation(s)
- N E Kucukboyaci
- Department of Psychiatry, University of California San Diego, CA, USA ; Multimodal Imaging Laboratory, University of California San Diego, CA, USA ; San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA
| | - N Kemmotsu
- Department of Psychiatry, University of California San Diego, CA, USA ; Multimodal Imaging Laboratory, University of California San Diego, CA, USA
| | - K M Leyden
- Multimodal Imaging Laboratory, University of California San Diego, CA, USA
| | - H M Girard
- San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA
| | - E S Tecoma
- Department of Neurosciences, University of California San Diego, CA, USA
| | - V J Iragui
- Department of Neurosciences, University of California San Diego, CA, USA
| | - C R McDonald
- Department of Psychiatry, University of California San Diego, CA, USA ; Multimodal Imaging Laboratory, University of California San Diego, CA, USA
| |
Collapse
|
33
|
Amarreh I, Meyerand ME, Stafstrom C, Hermann BP, Birn RM. Individual classification of children with epilepsy using support vector machine with multiple indices of diffusion tensor imaging. NEUROIMAGE-CLINICAL 2014; 4:757-64. [PMID: 24936426 PMCID: PMC4053650 DOI: 10.1016/j.nicl.2014.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Support vector machines (SVM) have recently been demonstrated to be useful for voxel-based MR image classification. In the present study we sought to evaluate whether this method is feasible in the classification of childhood epilepsy intractability based on diffusion tensor imaging (DTI), with adequate accuracy. We applied SVM in conjunction DTI indices of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD). DTI studies have reported white matter abnormalities in childhood-onset epilepsy, but the mechanisms underlying these abnormalities are not well understood. The aim of this study was to examine the relationship between epileptic seizures and cerebral white matter abnormalities identified by DTI in children with active compared to remitted epilepsy utilizing an automated and unsupervised classification method. METHODS The DTI data were tensor-derived indices including FA, MD, AD and RD in 49 participants including 20 children with epilepsy 5-6 years after seizure onset as compared to healthy controls. To determine whether there was normalization of white matter diffusion behavior following cessation of seizures and treatment, the epilepsy subjects were grouped into those with active versus remitted epilepsy. Group comparisons were previously made examining FA, MD and RD via whole-brain tract-based spatial statistics (TBSS). The SVM analysis was undertaken with the WEKA software package with 10-fold cross validation. Weighted sensitivity, specificity and accuracy were measured for all the DTI indices for two classifications: (1) controls vs. all children with epilepsy and (2) controls vs. children with remitted epilepsy vs. children with active epilepsy. RESULTS Using TBSS, significant differences were identified between controls and all children with epilepsy, between controls and children with active epilepsy, and also between the active and remitted epilepsy groups. There were no significant differences between the remitted epilepsy and controls on any DTI measure. In the SVM analysis, the best predictor between controls and all children with epilepsy was MD, with a sensitivity of 90-100% and a specificity between 96.6 and 100%. For the three-way classification, the best results were for FA with 100% sensitivity and specificity. CONCLUSION DTI-based SVM classification appears promising for distinguishing children with active epilepsy from either those with remitted epilepsy or controls, and the question that arises is whether it will prove useful as a prognostic index of seizure remission. While SVM can correctly identify children with active epilepsy from other groups' diagnosis, further research is needed to determine the efficacy of SVM as a prognostic tool in longitudinal clinical studies.
Collapse
Affiliation(s)
- Ishmael Amarreh
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health Madison, WI 53705, United States
| | - Mary E Meyerand
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health Madison, WI 53705, United States
| | - Carl Stafstrom
- Department of Neurology, University of Wisconsin School of Medicine and Public Health Madison, WI 53705, United States
| | - Bruce P Hermann
- Department of Neurology, University of Wisconsin School of Medicine and Public Health Madison, WI 53705, United States
| | - Rasmus M Birn
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health Madison, WI 53705, United States ; Department of Psychiatry, University of Wisconsin-Madison, United States
| |
Collapse
|
34
|
Yin XY, Qiu SJ, Liu ZY, Wang HZ, Xiong WF, Li SS, Wang Y. Extratemporal abnormalities of brain parenchyma in young adults with temporal lobe epilepsy: a diffusion tensor imaging study. Clin Radiol 2014; 69:589-96. [PMID: 24581963 DOI: 10.1016/j.crad.2014.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 11/19/2013] [Accepted: 01/07/2014] [Indexed: 01/01/2023]
Abstract
AIM To examine extratemporal abnormalities of the cerebral parenchyma in young adult temporal lobe epilepsy (TLE) patients using diffusion tensor imaging (DTI). MATERIALS AND METHODS The study comprised 20 adults with unilateral TLE and 20 controls. The fractional anisotropy (FA), apparent diffusion coefficient (ADC), parallel eigenvalue (λ∥), and perpendicular eigenvalue (λ⊥) were calculated in the regions of interest (ROIs) using a 3 T MRI system. ROIs included the anterior/posterior limb of the internal capsule (AIC/PIC), external capsule (EC), head of caudate nucleus (HCN), lenticular nucleus (LN), thalamus (TL), and genu/body/splenium of the corpus callosum (GCC/BCC/SCC). RESULTS Compared to controls, TLE patients showed lower FA in all ROIs; higher ADC in bilateral ECs, HCNs, TLs, and BCC; lower λ∥ in the ipsilateral LN and bilateral AICs, TL, and GCC; and higher λ⊥ in all ROIs except the bilateral PICs. In TLE patients, the ipsilateral TL had decreased FA compared with the contralateral TL. Pearson correlation analysis revealed a negative correlation between the ADC of the GCC and the age at onset of epilepsy; the λ∥ of the ipsilateral PIC and age at onset of epilepsy; the λ⊥ of the contralateral AIC and duration of epilepsy, respectively; and a positive correlation between the ADC of the GCC and the duration of epilepsy and the λ⊥ of the GCC and the duration of epilepsy, respectively. CONCLUSION The study revealed bilateral extratemporal abnormalities in young adult TLE patients compared with controls. In addition, TLE patients with younger age at onset or longer duration of epilepsy may have more serious extratemporal changes.
Collapse
Affiliation(s)
- X-Y Yin
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| | - S-J Qiu
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China.
| | - Z-Y Liu
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| | - H-Z Wang
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| | - W-F Xiong
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| | - S-S Li
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| | - Y Wang
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, PR China
| |
Collapse
|
35
|
Smallman RP, Barkus E, Azadbakht H, Embleton KV, Haroon HA, Lewis SW, Morris DM, Parker GJ, Rushe TM. MRI diffusion tractography study in individuals with schizotypal features: a pilot study. Psychiatry Res 2014; 221:49-57. [PMID: 24239094 DOI: 10.1016/j.pscychresns.2013.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 09/30/2013] [Accepted: 10/25/2013] [Indexed: 10/26/2022]
Abstract
Diffusion tensor imaging (DTI) studies have identified changes in white matter tracts in schizophrenia patients and those at high risk of transition. Schizotypal samples represent a group on the schizophrenia continuum that share some aetiological risk factors but without the confounds of illness. The aim of the current study was to compare tract microstructural coherence as measured by fractional anisotropy (FA) between 12 psychometrically defined schizotypes and controls. We investigated bilaterally the uncinate and arcuate fasciculi (UF and AF) via a probabilistic tractography algorithm (PICo), with FA values compared between groups. Partial correlations were also examined between measures of subclinical hallucinatory/delusional experiences and FA values. Participants with schizotypal features were found to have increased FA values in the left hemisphere UF only. In the whole sample there was a positive correlation between FA values and measures of hallucinatory experience in the right AF. These findings suggest subtle changes in microstructural coherence are found in individuals with schizotypal features, but are not similar to changes predominantly observed in clinical samples. Correlations between mild hallucinatory experience and FA values could indicate increasing tract coherence could be associated with symptom formation.
Collapse
Affiliation(s)
- Richard P Smallman
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester M13 9PT, UK; School of Psychological Sciences, University of Manchester, Manchester, UK.
| | - Emma Barkus
- School of Psychology, University of Wollongong, Wollongong, NSW, Australia
| | | | - Karl V Embleton
- School of Psychological Sciences, University of Manchester, Manchester, UK; Centre for Imaging Sciences, University of Manchester, Manchester, UK
| | - Hamied A Haroon
- Centre for Imaging Sciences, University of Manchester, Manchester, UK
| | - Shôn W Lewis
- Institute of Brain, Behaviour and Mental Health, University of Manchester, Manchester, UK
| | - David M Morris
- Centre for Imaging Sciences, University of Manchester, Manchester, UK
| | - Geoffrey J Parker
- Centre for Imaging Sciences, University of Manchester, Manchester, UK
| | - Teresa M Rushe
- School of Psychology, Queen's University Belfast, Belfast, UK
| |
Collapse
|
36
|
Bernhardt BC, Hong S, Bernasconi A, Bernasconi N. Imaging structural and functional brain networks in temporal lobe epilepsy. Front Hum Neurosci 2013; 7:624. [PMID: 24098281 PMCID: PMC3787804 DOI: 10.3389/fnhum.2013.00624] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 09/09/2013] [Indexed: 11/24/2022] Open
Abstract
Early imaging studies in temporal lobe epilepsy (TLE) focused on the search for mesial temporal sclerosis, as its surgical removal results in clinically meaningful improvement in about 70% of patients. Nevertheless, a considerable subgroup of patients continues to suffer from post-operative seizures. Although the reasons for surgical failure are not fully understood, electrophysiological and imaging data suggest that anomalies extending beyond the temporal lobe may have negative impact on outcome. This hypothesis has revived the concept of human epilepsy as a disorder of distributed brain networks. Recent methodological advances in non-invasive neuroimaging have led to quantify structural and functional networks in vivo. While structural networks can be inferred from diffusion MRI tractography and inter-regional covariance patterns of structural measures such as cortical thickness, functional connectivity is generally computed based on statistical dependencies of neurophysiological time-series, measured through functional MRI or electroencephalographic techniques. This review considers the application of advanced analytical methods in structural and functional connectivity analyses in TLE. We will specifically highlight findings from graph-theoretical analysis that allow assessing the topological organization of brain networks. These studies have provided compelling evidence that TLE is a system disorder with profound alterations in local and distributed networks. In addition, there is emerging evidence for the utility of network properties as clinical diagnostic markers. Nowadays, a network perspective is considered to be essential to the understanding of the development, progression, and management of epilepsy.
Collapse
Affiliation(s)
- Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada ; Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences Leipzig, Germany
| | | | | | | |
Collapse
|
37
|
Amarreh I, Dabbs K, Jackson DC, Jones JE, Meyerand ME, Stafstrom CE, Hsu DA, Seidenberg M, Hermann BP. Cerebral white matter integrity in children with active versus remitted epilepsy 5 years after diagnosis. Epilepsy Res 2013; 107:263-71. [PMID: 24148888 DOI: 10.1016/j.eplepsyres.2013.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 08/28/2013] [Accepted: 09/17/2013] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Diffusion tensor imaging (DTI) studies have reported white matter abnormalities in childhood-onset epilepsy, but the mechanisms and timing underlying these abnormalities, and their resolution, are not well understood. This study examined white matter integrity in children with active versus remitted epilepsy. METHODS Tract-based spatial statistics (TBSS) was used to examine whole-brain DTI indices of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in 20 children with epilepsy 5-6 years after diagnosis, compared to 29 healthy controls. To determine the status of white matter following cessation of seizures, participants with epilepsy were classified as active versus remitted and comparisons included: (1) controls versus all children with epilepsy, (2) controls versus children with remitted seizures, (3) controls versus children with active seizures, and (4) children with active versus remitted epilepsy. RESULTS In the active compared to remitted epilepsy group, significantly higher FA and lower MD, AD and RD values were dispersed in the internal capsule, cingulum, body of the corpus callosum, superior corona radiata and superior fronto-occipital fasciculus. Similar differences were found between the active epilepsy and the control group. There were no significant differences between the remitted epilepsy and control groups. CONCLUSION Children with active epilepsy differed in white matter integrity compared to children with remitted epilepsy and healthy controls. It remains to be determined whether these findings represent the outcomes of seizure remission versus an initial biomarker for those children who will ultimately have intractable epilepsy.
Collapse
Affiliation(s)
- Ishmael Amarreh
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Sato T, Maruyama N, Hoshida T, Minato K. Correlation between uncinate fasciculus and memory tasks in healthy individual using diffusion tensor tractography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:424-7. [PMID: 23365919 DOI: 10.1109/embc.2012.6345958] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tractography is a procedure that can track and demonstrate the 3D neural tracts of the white matter of the brain. The images of the brain are obtained by analyzing the diffusion tensor, identification of which can provide the anatomical connections of the brain. Studying these connections is integral to the understanding of the brain function. Specifically, the uncinate fasciculus (UF), which is the white matter in the human brain, is said to be related to cognitive function. The UF tractography is calculated using diffusion tensor imaging (DTI) parameter. Studies have shown that the DTI parameter of dementia patients is lower than that of healthy individuals. It is also suggested that the DTI parameter of healthy individuals decreases with age. In addition, the WMS-R score, which is indicative of general memory, verbal memory and other cognitive functions, of the elderly are lower than of the young. However, there is no report yet that has holistically investigated DTI parameter and the memory functions. Thus, in this research, we have calculated the correlation coefficient between the DTI parameter of UF and WMS-R score. Our result shows that the correlation coefficient of diffusivity of the fiber direction and visual memory of a left UF is -0.226 at the maximum. Correlation between DTI measurement and memory performance suggests the relationships between the UF and function in memory tasks lateralization. Our finding matches previous reports on the correlation between FA in the left, or L1 in the right UF, and performance on visual memory.
Collapse
Affiliation(s)
- T Sato
- Nara Institute of Science and Technology, Ikoma, Nara 6300192, Japan.
| | | | | | | |
Collapse
|
39
|
Von Der Heide RJ, Skipper LM, Klobusicky E, Olson IR. Dissecting the uncinate fasciculus: disorders, controversies and a hypothesis. ACTA ACUST UNITED AC 2013; 136:1692-707. [PMID: 23649697 DOI: 10.1093/brain/awt094] [Citation(s) in RCA: 522] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The uncinate fasciculus is a bidirectional, long-range white matter tract that connects lateral orbitofrontal cortex and Brodmann area 10 with the anterior temporal lobes. Although abnormalities in the uncinate fasciculus have been associated with several psychiatric disorders and previous studies suggest it plays a putative role in episodic memory, language and social emotional processing, its exact function is not well understood. In this review we summarize what is currently known about the anatomy of the uncinate, we review its role in psychiatric and neurological illnesses, and we evaluate evidence related to its putative functions. We propose that an overarching role of the uncinate fasciculus is to allow temporal lobe-based mnemonic associations (e.g. an individual's name + face + voice) to modify behaviour through interactions with the lateral orbitofrontal cortex, which provides valence-based biasing of decisions. The bidirectionality of the uncinate fasciculus information flow allows orbital frontal cortex-based reward and punishment history to rapidly modulate temporal lobe-based mnemonic representations. According to this view, disruption of the uncinate may cause problems in the expression of memory to guide decisions and in the acquisition of certain types of learning and memory. Moreover, uncinate perturbation should cause problems that extend beyond memory to include social-emotional problems owing to people and objects being stripped of personal value and emotional history and lacking in higher-level motivational value.
Collapse
|
40
|
Oguz KK, Tezer I, Sanverdi E, Has AC, Bilginer B, Dolgun A, Saygi S. Effect of patient sex on white matter alterations in unilateral medial temporal lobe epilepsy with hippocampal sclerosis assessed by diffusion tensor imaging. AJNR Am J Neuroradiol 2013; 34:1010-5. [PMID: 23153868 DOI: 10.3174/ajnr.a3328] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Studies shows ictal behavior and symptoms are affected by patient sex in temporal lobe epilepsy. The purpose of our study was to determine whether alterations in the WM as assessed by DTI display different patterns in male and female patients with unilateral HS. MATERIALS AND METHODS Patients with unilateral HS were categorized as women with right HS (n=12), men with right HS (n=10), women with left HS (n=12), and men with left HS (n=10). DTI of the brain along 64 noncollinear directions was obtained from 44 patients and 37 sex-matched control participants. We used TBSS to analyze whole-brain WM. Regions with significant changes of FA and MD, and their mean FA, MD, total number of significant voxels, and asymmetry indices were determined for each group. RESULTS All groups showed bilateral and extensive reductions of FA and elevated MD in the WM, more prominent ipsilateral to the affected hippocampus. The total number of voxels with decreased FA in patients compared with that of control participants was higher in women with right HS (24,727 vs 5,459) and in men with left HS (27,332 vs 14,013) than in their counterparts. Changes in MD associated with right HS were more extensive in both men and women (right vs left HS, women: 16,926 vs 5,458; men: 5,389 vs 4,764) than in those with left HS. In patients with right HS, the ipsilateral cingulum, uncinate fasciculus, internal and external capsules, and right acoustic radiation were involved extensively in women. CONCLUSIONS Women and men showed different patterns in extent of WM alterations associated with HS.
Collapse
Affiliation(s)
- K K Oguz
- Bilkent University, National Magnetic Resonance Research Center, Bilkent, Ankara, Turkey.
| | | | | | | | | | | | | |
Collapse
|
41
|
Takao H, Hayashi N, Ohtomo K. White matter microstructure asymmetry: effects of volume asymmetry on fractional anisotropy asymmetry. Neuroscience 2012; 231:1-12. [PMID: 23219841 DOI: 10.1016/j.neuroscience.2012.11.038] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 11/20/2012] [Accepted: 11/21/2012] [Indexed: 12/13/2022]
Abstract
Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.
Collapse
Affiliation(s)
- H Takao
- Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
| | | | | |
Collapse
|
42
|
Contralateral insular involvement producing false lateralizing signs in bitemporal epilepsy: A stereo-encephalography case report. Seizure 2012; 21:816-9. [DOI: 10.1016/j.seizure.2012.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 08/30/2012] [Accepted: 08/31/2012] [Indexed: 11/23/2022] Open
|
43
|
Liu M, Concha L, Lebel C, Beaulieu C, Gross DW. Mesial temporal sclerosis is linked with more widespread white matter changes in temporal lobe epilepsy. NEUROIMAGE-CLINICAL 2012; 1:99-105. [PMID: 24179742 PMCID: PMC3757721 DOI: 10.1016/j.nicl.2012.09.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/19/2012] [Accepted: 09/22/2012] [Indexed: 12/04/2022]
Abstract
Temporal lobe epilepsy patients with unilateral mesial temporal sclerosis (TLE + uMTS) have been demonstrated to have extensive white matter abnormalities both ipsilateral and contralateral to the seizure onset zone. However, comparatively less is known about the white matter integrity of TLE patients without MTS (non-lesional TLE, nl-TLE). The purpose of the study was to investigate the diffusion properties of thirteen major white matter tracts in patients with TLE + uMTS and nl-TLE. Diffusion tensor imaging (DTI) was performed on 23 TLE + uMTS (15 left MTS and 8 right MTS), 15 nl-TLE and 21 controls. Thirteen tracts were delineated by tractography and their diffusion parameters compared for the two TLE groups relative to controls, with left and right hemispheres combined per tract. A subgroup analysis investigated left and right MTS separately. Compared to controls, reduced anisotropy was detected in ten tracts for TLE + uMTS, but only the parahippocampal cingulum and tapetum for nl-TLE. Right MTS subgroup showed reduced anisotropy in 7 tracts bilaterally (3 limbic, 3 association, 1 projection) and 2 tracts ipsilaterally (1 association, 1 projection) and the body of the corpus callosum whereas the left MTS subgroup showed reduced anisotropy in 4 tracts bilaterally (2 limbic, 1 association, 1 projection) and 2 tracts ipsilaterally (1 limbic, 1 association). Diffusion abnormalities in tracts were observed within and beyond the temporal lobe in TLE + uMTS and were more widespread than in nl-TLE. Patients with right MTS had more extensive, bilateral abnormalities in comparison to left MTS. These findings suggest different dysfunctional networks in TLE patients with and without MTS.
Collapse
Affiliation(s)
- Min Liu
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | | | | | | | | |
Collapse
|
44
|
Bartoli A, Vulliemoz S, Haller S, Schaller K, Seeck M. Imaging techniques for presurgical evaluation of temporal lobe epilepsy. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/iim.12.28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
45
|
Otte WM, van Eijsden P, Sander JW, Duncan JS, Dijkhuizen RM, Braun KPJ. A meta-analysis of white matter changes in temporal lobe epilepsy as studied with diffusion tensor imaging. Epilepsia 2012; 53:659-67. [PMID: 22379949 DOI: 10.1111/j.1528-1167.2012.03426.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
PURPOSE Diffusion tensor imaging (DTI) is used increasingly to study white matter integrity in people with temporal lobe epilepsy (TLE). Most studies report fractional anisotropy (FA) decrease and mean diffusivity (MD) increase in multiple white matter regions. The disturbance of white matter integrity varies across studies and between regions. We aimed to obtain a more consistent estimate of white matter diffusion characteristics and relate these to the distance from the seizure focus. METHODS Studies comparing diffusion characteristics of people with epilepsy with those of healthy controls were systematically reviewed and quantified using random and mixed effects meta analysis. In addition to the overall meta-analysis, pooled FA and MD differences were determined per hemisphere and white matter category separately. KEY FINDINGS We included 13 cross-sectional studies. The pooled FA difference for all white matter was -0.026 (95% confidence interval [CI] -0.033 to -0.019) and MD difference was 0.028 × 10(-3) mm(2)/s (95% CI 0.015-0.04). FA was reduced significantly in people with TLE compared with healthy controls in both ipsilateral (mean difference -0.03) and contralateral white matter (-0.02). MD was significantly increased ipsilaterally and contralaterally. MD differed significantly between white matter connected to the affected temporal lobe and remote white matter. SIGNIFICANCE The meta-analysis provides a better estimation of the true diffusion characteristics. White matter structural integrity in TLE is disturbed more severely in the ipsilateral than in the contralateral hemisphere, and tracts closely connected with the affected temporal lobe are most disturbed. The exact underlying mechanisms remain to be elucidated.
Collapse
Affiliation(s)
- Willem M Otte
- Department of Pediatric Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
| | | | | | | | | | | |
Collapse
|
46
|
Yin X, Han Y, Ge H, Xu W, Huang R, Zhang D, Xu J, Fan L, Pang Z, Liu S. Inferior frontal white matter asymmetry correlates with executive control of attention. Hum Brain Mapp 2011; 34:796-813. [PMID: 22110013 DOI: 10.1002/hbm.21477] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 08/11/2011] [Accepted: 09/02/2011] [Indexed: 11/08/2022] Open
Abstract
White matter (WM) asymmetries of the human brain have been well documented using diffusion tensor imaging (DTI). However, the relationship between WM asymmetry pattern and cognitive performance is poorly understood. By means of tract-based spatial statistics (TBSS) and voxel-based analyses of whole brain, this study examined the WM asymmetries and the correlations between WM integrity/asymmetries and three distinct components of attention, namely alerting, orienting, and executive control (EC), which were assessed by attention network test (ANT). We revealed a number of WM anisotropy asymmetries, including leftward asymmetry of cingulum, corticospinal tract and cerebral peduncle, rightward asymmetry of internal capsule, superior longitudinal fasciculus and posterior corona radiata, as well as heterogeneous asymmetries in anterior corpus callosum and anterior corona radiata (ACR). Moreover, specific correlation was found between asymmetric pattern of inferior frontal ACR and EC performance. Additionally, this study also proposed that there were no significant relationships of WM anisotropy asymmetries to alerting and orienting functions. Further clusters of interest analyses and probabilistic fiber tracking validated our findings. In conclusion, there are a number of differences in WM integrity between human brain hemispheres. Specially, the anisotropy asymmetry in inferior frontal ACR plays a crucial role in EC function. Our finding is supportive of the functional studies of inferior frontal regions and in keeping with the theory of the brain lateralization on human ventral attention system.
Collapse
Affiliation(s)
- Xuntao Yin
- Research Center for Sectional and Imaging Anatomy, Shandong University School of Medicine, Jinan, Shandong, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Baur V, Brühl AB, Herwig U, Eberle T, Rufer M, Delsignore A, Jäncke L, Hänggi J. Evidence of frontotemporal structural hypoconnectivity in social anxiety disorder: A quantitative fiber tractography study. Hum Brain Mapp 2011; 34:437-46. [PMID: 22076860 DOI: 10.1002/hbm.21447] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/08/2011] [Accepted: 07/29/2011] [Indexed: 11/08/2022] Open
Abstract
Investigation of the brain's white matter fiber tracts in social anxiety disorder (SAD) may provide insight into the underlying pathophysiology. Because models of pathological anxiety posit altered frontolimbic interactions, the uncinate fasciculus (UF) connecting (orbito-) frontal and temporal areas including the amygdala is of particular interest. Microstructural alterations in parts of the UF have been reported previously, whereas examination of the UF as discrete fiber tract with regard to more large-scale properties is still lacking. Diffusion tensor imaging was applied in 25 patients with generalized SAD and 25 healthy control subjects matched by age and gender. By means of fiber tractography, the UF was reconstructed for each participant. The inferior fronto-occipital fasciculus (IFOF), originating from the frontal cortex similarly to the UF, was additionally included as control tract. Volume and fractional anisotropy (FA) were compared between the groups for both tracts. Volume of left and right UF was reduced in patients with SAD, reaching statistical significance for the left UF. Bilateral IFOF volume was not different between groups. A similar pattern was observed for FA. Reduced volume of the left UF in SAD fits well into pathophysiological models of anxiety, as it suggests deficient structural connectivity between higher-level control areas in the orbitofrontal cortex and more basal limbic areas like the amygdala. The results point to a specific role of the left UF with regard to altered white matter volume in SAD. However, results should be replicated and functional correlates of altered UF volume be determined in future studies.
Collapse
Affiliation(s)
- Volker Baur
- Division Neuropsychology, Institute of Psychology, University of Zurich, Switzerland.
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Takao H, Hayashi N, Ohtomo K. White matter asymmetry in healthy individuals: a diffusion tensor imaging study using tract-based spatial statistics. Neuroscience 2011; 193:291-9. [PMID: 21824507 DOI: 10.1016/j.neuroscience.2011.07.041] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 12/13/2022]
Affiliation(s)
- H Takao
- Department of Radiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
| | | | | |
Collapse
|
49
|
McDonald CR, Taylor J, Hamberger M, Helmstaedter C, Hermann BP, Schefft B. Future directions in the neuropsychology of epilepsy. Epilepsy Behav 2011; 22:69-76. [PMID: 21795122 DOI: 10.1016/j.yebeh.2011.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 06/05/2011] [Indexed: 11/17/2022]
Abstract
Two important themes for future clinical research in the neuropsychology of epilepsy are proposed: (1) the neurobiological abnormalities that underlie neuropsychological impairment in people with epilepsy, and (2) neuropsychological status of persons with new-onset epilepsy.
Collapse
Affiliation(s)
- Carrie R McDonald
- Multimodal Imaging Laboratory, Department of Psychiatry, University of California, San Diego, San Diego, CA, USA
| | | | | | | | | | | |
Collapse
|
50
|
Kim CH, Chung CK, Koo BB, Lee JM, Kim JS, Lee SK. Changes in language pathways in patients with temporal lobe epilepsy: diffusion tensor imaging analysis of the uncinate and arcuate fasciculi. World Neurosurg 2011; 75:509-16. [PMID: 21600505 DOI: 10.1016/j.wneu.2010.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 04/26/2010] [Accepted: 11/02/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE The language pathways consist of ventral and dorsal systems connected via the uncinate fasciculus and arcuate fasciculus, respectively. Seizures in medial temporal lobe epilepsy (mTLE) affect both tracts. Previous studies, however, have focused on the arcuate fasciculus to explain the language disturbance in mTLE. In contrast, we compared changes in both the uncinate and arcuate fasciculi using diffusion tensor imaging. METHODS Thirteen patients with left mTLE and 12 with right mTLE were studied. The Wada test showed left dominance for language in all these patients. Sixteen healthy right-handed subjects were also studied. The mean fractional anisotropy and mean apparent diffusion coefficient with their lateralization index of two fasciculi were compared between hemispheres and between subjects. RESULTS The mean apparent diffusion coefficient of the arcuate and uncinate fasciculi in both left- and right-mTLE patients increased bilaterally compared with that in healthy subjects. In left mTLE, the fractional anisotropy of the uncinate fasciculus was lower ipsilaterally (P = 0.002) and was significantly lateralized contralaterally (P < 0.001) compared with control subjects, whereas the fractional anisotropy of the arcuate fasciculus showed no lateralization (P = 0.577). In right mTLE, such a difference was not prominent. CONCLUSION The seizure network affects both arcuate and uncinate fasciculi bilaterally in both left- and right-mTLE patients. The change is most prominent in the left uncinate fasciculus in left mTLE.
Collapse
Affiliation(s)
- Chi Heon Kim
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul, South Korea
| | | | | | | | | | | |
Collapse
|