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Thomas TOURDIAS




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Cursus:
MD: Radiology, Bordeaux (2008)
PhD: Neurosciences, Bordeaux (2011)
Post doc: Stanford University, CA, USA (2013)
Professeur des Universités - Praticien Hospitalier; PU PH (2016)






75 publication(s) depuis Décembre 2006:


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Les IF indiqués ont été collectés par le Web of Sciences en


2018 | front neurol   IF 2.6
Impact of Lesion Load Thresholds on Alberta Stroke Program Early Computed Tomographic Score in Diffusion-Weighted Imaging.
Schroder J, Cheng B, Malherbe C, Ebinger M, Kohrmann M, Wu O, Kang DW, Liebeskind DS, Tourdias T, Singer OC, Campbell B, Luby M, Warach S, Fiehler J, Kemmling A, Fiebach JB, Gerloff C, Thomalla G

Abstract:
Background and aims: Assessment of ischemic lesions on computed tomography or MRI diffusion-weighted imaging (DWI) using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to guide acute stroke treatment. However, it has never been defined how many voxels need to be affected to label a DWI-ASPECTS region ischemic. We aimed to assess the effect of various lesion load thresholds on DWI-ASPECTS and compare this automated analysis with visual rating. Materials and methods: We analyzed overlap of individual DWI lesions of 315 patients from the previously published predictive value of fluid-attenuated inversion recovery study with a probabilistic ASPECTS template derived from 221 CT images. We applied multiple lesion load thresholds per DWI-ASPECTS region (>0, >1, >10, and >20% in each DWI-ASPECTS region) to compute DWI-ASPECTS for each patient and compared the results to visual reading by an experienced stroke neurologist. Results: By visual rating, median ASPECTS was 9, 84 patients had a DWI-ASPECTS score 0, >1-, >10-, and >20%-thresholds, median DWI-ASPECTS was 1, 5, 8, and 10; 97.1% (306), 72.7% (229), 41% (129), and 25.7% (81) had DWI-ASPECTS 0%: kappaw = 0.020 1%: kappaw = 0.151; 10%: kappaw = 0.386; 20% kappaw = 0.381). Agreement for dichotomized DWI-ASPECTS ranged from fair to substantial (10% kappa = 0.48; >20% kappa = 0.45; 10% kappa = 0.528; and >20% kappa = 0.695). Conclusion: Overall agreement between automated and the standard used visual scoring is low regardless of the lesion load threshold used. However, dichotomized scoring achieved more comparable results. Varying lesion load thresholds had a critical impact on patient selection by ASPECTS. Of note, the relatively low lesion volume and lack of patients with large artery occlusion in our cohort may limit generalizability of these findings.




2018 | front neurol   IF 2.6
Differential Gray Matter Vulnerability in the 1 Year Following a Clinically Isolated Syndrome.
Koubiyr I, Deloire M, Coupe P, Dulau C, Besson P, Moroso A, Planche V, Tourdias T, Brochet B, Ruet A

Abstract:
Background and purpose: Whether some gray matter (GM) regions are differentially vulnerable at the early stages of MS is still unknown. The objective of this study is to investigate whether deep and cortical GM are differentially vulnerable after a clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS). Methods: Fifty-six patients with CIS (PwCIS) and 38 healthy controls (HC) had conventional and diffusion tensor imaging (DTI) at baseline and 46 PwCIS and 20 HC were rescanned after 1 year. Deep GM (DGM) volumes, cortical thickness (CTh), and DTI metrics (FA: fractional anisotropy; MD: mean diffusivity) within these structures were calculated for each participant at each time-point and compared between PwCIS and HC. Linear regression models were used to investigate whether baseline DTI parameters could predict GM volume loss over time. Results: At baseline, GM volumes did not differ between PwCIS and HC, but hippocampal MD was higher in PwCIS than HC (p < 0.01). Over 1 year, GM alterations became more widespread with putamen and hippocampus volumes decreasing in PwCIS (p < 0.01), and cortical thinning in different parts of the cortex along with a significant increase of MD. Hippocampus MD at baseline could predict its volume loss (R (2) = 0.159; p < 0.05) and cortical thinning was associated to microstructural damage (Spearman's rho ranging from -0.424 to -0.603 with p < 0.003). Conclusion: Along with MS being a diffuse inflammatory disease, GM showed a differential vulnerability at the early stage spreading from hippocampus to the cortex. Hippocampus volume loss could be predicted by its MD at baseline.




10/2017 | J Neurol   IF 4.2
Optic neuritis in patients with anti-MOG antibodies spectrum disorder: MRI and clinical features from a large multicentric cohort in France.
Biotti D, Bonneville F, Tournaire E, Ayrignac X, Dalliere CC, Mahieu L, Vignal C, Dulau C, Brochet B, Ruet A, Ouallet JC, Gout O, Heran F, Menjot de Champfleur N, Tourdias T, Deneve M, Labauge P, Deschamps R

Abstract:





08/2017 | brain behav   IF 2.1
Pattern separation performance is decreased in patients with early multiple sclerosis.
Planche V, Ruet A, Charre-Morin J, Deloire M, Brochet B, Tourdias T

Abstract:
BACKGROUND: Hippocampal-dependent memory impairment is frequent and occurs early during the course of multiple sclerosis (MS). While mechanisms responsible for episodic memory dysfunction in patients with MS remain largely unknown, dentate gyrus structure has been suggested as particularly vulnerable at the early stage of the disease. If true, we hypothesized that the pattern separation component of episodic memory (a function known to be critically dependent to dentate gyrus function) would be impaired in patients with early MS (PweMS). METHODS: Thirty eight participants (19 PweMS and 19 healthy controls matched on age, gender and education level) were tested with a behavioral pattern separation task and also for information processing speed and visuospatial episodic memory. RESULTS: We report a significant decrease in pattern separation performance in PweMS compared to healthy controls (27.07 vs. 40.01, p = .030 after Holm-Bonferroni correction, d = 1.02) together with a significantly higher pattern completion rate (56.11 vs. 40.95, p = .004 after Holm-Bonferroni correction, d = 1.07) while no difference was found among groups for information processing speed and 'global' visuospatial episodic memory regarding learning, long-term recall or recognition. CONCLUSION: Our results suggest that behavioral pattern separation task can detect subtle memory decline in patients with MS and argue for early dentate gyrus dysfunction during the course of the disease.




08/2017 | Stroke   IF 6
Admission Brain Cortical Volume: An Independent Determinant of Poststroke Cognitive Vulnerability.
Sagnier S, Catheline G, Dilharreguy B, Munsch F, Bigourdan A, Poli M, Debruxelles S, Olindo S, Renou P, Rouanet F, Dousset V, Tourdias T, Sibon I

Abstract:
BACKGROUND AND PURPOSE: Several markers of poststroke cognitive impairment have been reported. The role of brain cortical volume remains uncertain. The aim of this study was to evaluate the influence of brain cortical volume on cognitive outcomes using a voxel-based morphometry approach in subjects without prestroke dementia. METHODS: Ischemic stroke patients were prospectively recruited 24 to 72 hours post stroke (M0). Cognition was evaluated at M0, 3 months, and 1 year (M12) using the Montreal Cognitive Assessment, the Isaacs set test, and the Zazzo's cancellation task. A 3-T brain magnetic resonance imaging was performed at M0. Grey matter (GM) was segmented using Statistical Parametric Mapping 12 software. Association between global GM volume and cognitive score slopes between M0 and M12 was evaluated using a linear mixed model. Correlations between focal GM volumes and changes in cognitive performance were evaluated using Statistical Parametric Mapping 12. RESULTS: Two-hundred forty-eight patients were included (mean age 65+/-SD 14 years old, 66% men). Global GM volume was significantly associated with changes in Montreal Cognitive Assessment scores (beta=0.01; P=0.04) and in the number of errors on the Zazzo's cancellation task (beta=-0.02; P=0.04) independently of other clinical/radiological confounders. Subjects with lower GM volumes in the left fronto-temporo-insular cortex were more vulnerable to transient Montreal Cognitive Assessment and Isaacs set test impairment. Subjects with lower GM volumes in right temporo-insular cortex, together with basal ganglia, were more vulnerable to transient cognitive impairment on the Zazzo's cancellation task. CONCLUSIONS: Smaller cortical volumes in fronto-temporo-insular areas measured 24 to 72 hours post stroke are associated with cognitive vulnerability in the subacute stroke phase.




01/07/2017 | Brain   IF 11.8
Thalamic alterations remote to infarct appear as focal iron accumulation and impact clinical outcome.
Kuchcinski G, Munsch F, Lopes R, Bigourdan A, Su J, Sagnier S, Renou P, Pruvo JP, Rutt BK, Dousset V, Sibon I, Tourdias T

Abstract:
See Duering and Schmidt (doi:10.1093/awx135) for a scientific commentary on this article.Thalamic alterations have been observed in infarcts initially sparing the thalamus but interrupting thalamo-cortical or cortico-thalamic projections. We aimed at extending this knowledge by demonstrating with in vivo imaging sensitive to iron accumulation, one marker of neurodegeneration, that (i) secondary thalamic alterations are focally located in specific thalamic nuclei depending on the initial infarct location; and (ii) such secondary alterations can contribute independently to the long-term outcome. To tackle this issue, 172 patients with an infarct initially sparing the thalamus were prospectively evaluated clinically and with magnetic resonance imaging to quantify iron through R2* map at 24-72 h and at 1-year follow-up. An asymmetry index was used to compare R2* within the thalamus ipsilateral versus contralateral to infarct and we focused on the 95th percentile of R2* as a metric of high iron content. Spatial distribution within the thalamus was analysed on an average R2* map from the entire cohort. The asymmetry index of the 95th percentile within individual nuclei (medio-dorsal, pulvinar, lateral group) were compared according to the initial infarct location in simple and multiple regression analyses and using voxel-based lesion-symptom mapping. Associations between the asymmetry index of the 95th percentile and functional, cognitive and emotional outcome were calculated in multiple regression models. We showed that R2* was not modified at 24-72 h but showed heterogeneous increase at 1 year mainly within the medio-dorsal and pulvinar nuclei. The asymmetry index of the 95th percentile within the medio-dorsal nucleus was significantly associated with infarcts involving anterior areas (frontal P = 0.05, temporal P = 0.02, lenticular P = 0.01) while the asymmetry index of the 95th percentile within the pulvinar nucleus was significantly associated with infarcts involving posterior areas (parietal P = 0.046, temporal P < 0.001) independently of age, gender and infarct volume, which was confirmed by voxel-based lesion-symptom mapping. The asymmetry index of the 95th percentile within the entire thalamus at 1 year was independently associated with poor functional outcome (P = 0.04), poor cognitive outcome (P = 0.03), post-stroke anxiety (P = 0.04) and post-stroke depression (P = 0.02). We have therefore identified that iron accumulates within the thalamus ipsilateral to infarct after a delay with a focal distribution that is strongly linked to the initial infarct location (in relation with the pattern of connectivity between thalamic nuclei and cortical areas or deep nuclei), which independently contributes to functional, cognitive and emotional outcome.




2017 | PLoS ONE   IF 2.8
Lesions in deep gray nuclei after severe traumatic brain injury predict neurologic outcome.
Clarencon F, Bardinet E, Martinerie J, Pelbarg V, Menjot de Champfleur N, Gupta R, Tollard E, Soto-Ares G, Ibarrola D, Schmitt E, Tourdias T, Degos V, Yelnik J, Dormont D, Puybasset L, Galanaud D

Abstract:
PURPOSE: This study evaluates the correlation between injuries to deep gray matter nuclei, as quantitated by lesions in these nuclei on MR T2 Fast Spin Echo (T2 FSE) images, with 6-month neurological outcome after severe traumatic brain injury (TBI). MATERIALS AND METHODS: Ninety-five patients (80 males, mean age = 36.7y) with severe TBI were prospectively enrolled. All patients underwent a MR scan within the 45 days after the trauma that included a T2 FSE acquisition. A 3D deformable atlas of the deep gray matter was registered to this sequence; deep gray matter lesions (DGML) were evaluated using a semi-quantitative classification scheme. The 6-month outcome was dichotomized into unfavorable (death, vegetative or minimally conscious state) or favorable (minimal or no neurologic deficit) outcome. RESULTS: Sixty-six percent of the patients (63/95) had both satisfactory registration of the 3D atlas on T2 FSE and available clinical follow-up. Patients without DGML had an 89% chance (P = 0.0016) of favorable outcome while those with bilateral DGML had an 80% risk of unfavorable outcome (P = 0.00008). Multivariate analysis based on DGML accurately classified patients with unfavorable neurological outcome in 90.5% of the cases. CONCLUSION: Lesions in deep gray matter nuclei may predict long-term outcome after severe TBI with high sensitivity and specificity.




2017 | PLoS ONE   IF 2.8
Microstructural analyses of the posterior cerebellar lobules in relapsing-onset multiple sclerosis and their implication in cognitive impairment.
Moroso A, Ruet A, Lamargue-Hamel D, Munsch F, Deloire M, Coupe P, Charre-Morin J, Saubusse A, Ouallet JC, Planche V, Tourdias T, Dousset V, Brochet B

Abstract:
BACKGROUND: The posterior cerebellar lobules seem to be the anatomical substrate of cognitive cerebellar processes, but their microstructural alterations in multiple sclerosis (MS) remain unclear. OBJECTIVES: To correlate diffusion metrics in lobules VI to VIIIb in persons with clinically isolated syndrome (PwCIS) and in cognitively impaired persons with MS (CIPwMS) with their cognitive performances. METHODS: Sixty-nine patients (37 PwCIS, 32 CIPwMS) and 36 matched healthy subjects (HS) underwent 3T magnetic resonance imaging, including 3D T1-weighted and diffusion tensor imaging (DTI). Fractional anisotropy (FA) and mean diffusivity (MD) were calculated within each lobule and in the cerebellar peduncles. We investigated the correlations between cognitive outcomes and the diffusion parameters of cerebellar sub-structures and performed multiple linear regression analysis to predict cognitive disability. RESULTS: FA was generally lower and MD was higher in the cerebellum and specifically in the vermis Crus II, lobules VIIb and VIIIb in CIPwMS compared with PwCIS and HS. In hierarchical regression analyses, 31% of the working memory z score variance was explained by FA in the left lobule VI and in the left superior peduncle. Working memory was also associated with MD in the vermis Crus II. FA in the left lobule VI and right VIIIa predicted part of the information processing speed (IPS) z scores. CONCLUSION: DTI indicators of cerebellar microstructural damage were associated with cognitive deficits in MS. Our results suggested that cerebellar lobular alterations have an impact on attention, working memory and IPS.




2017 | Front Aging Neurosci   IF 3.6
Gait Change Is Associated with Cognitive Outcome after an Acute Ischemic Stroke.
Sagnier S, Renou P, Olindo S, Debruxelles S, Poli M, Rouanet F, Munsch F, Tourdias T, Sibon I

Abstract:
Background: Cognition and gait have often been studied separately after stroke whereas it has been suggested that these two domains could interact through a cognitive-motor interference. Objective: To evaluate the influence of gait changes on cognitive outcome after an ischemic stroke (IS). Methods: We conducted a prospective and monocentric study including patients admitted for an acute supratentorial IS with a National Institute of Health Stroke Score



2017 | Brain   IF 11.8
Thalamic alterations remote to infarct appear as focal iron accumulation and impact clinical outcome
Kuchcinski G, Munsch F, Lopes R, Bigourdan A, Su J, Sagnier S, Renou P, Pruvo JP, Rutt BK, Dousset V, Tourdias T

Abstract: