Neurocentre Magendie

Vincent DOUSSET




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70 publication(s) depuis Février 1995:


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12/11/2016 | Brain Behav Immun   IF 5.9
Selective dentate gyrus disruption causes memory impairment at the early stage of experimental multiple sclerosis.
Planche V, Panatier A, Hiba B, Ducourneau EG, Raffard G, Dubourdieu N, Maitre M, Leste-Lasserre T, Brochet B, Dousset V, Desmedt A, Oliet SH, Tourdias T

Abstract:
Memory impairment is an early and disabling manifestation of multiple sclerosis whose anatomical and biological substrates are still poorly understood. We thus investigated whether memory impairment encountered at the early stage of the disease could be explained by a differential vulnerability of particular hippocampal subfields. By using experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, we identified that early memory impairment was associated with selective alteration of the dentate gyrus as pinpointed in vivo with diffusion-tensor-imaging (DTI). Neuromorphometric analyses and electrophysiological recordings confirmed dendritic degeneration, alteration in glutamatergic synaptic transmission and impaired long-term synaptic potentiation selectively in the dentate gyrus, but not in CA1, together with a more severe pattern of microglial activation in this subfield. Systemic injections of the microglial inhibitor minocycline prevented DTI, morphological, electrophysiological and behavioral impairments in EAE-mice. Furthermore, daily infusions of minocycline specifically within the dentate gyrus were sufficient to prevent memory impairment in EAE-mice while infusions of minocycline within CA1 were inefficient. We conclude that early memory impairment in EAE is due to a selective disruption of the dentate gyrus associated with microglia activation. These results open new pathophysiological, imaging, and therapeutic perspectives for memory impairment in multiple sclerosis.




27/10/2016 | J Neurol Neurosurg Psychiatry
Posterior lobules of the cerebellum and information processing speed at various stages of multiple sclerosis.
Moroso A, Ruet A, Lamargue-Hamel D, Munsch F, Deloire M, Coupe P, Ouallet JC, Planche V, Moscufo N, Meier DS, Tourdias T, Guttmann CR, Dousset V, Brochet B

Abstract:
BACKGROUND: Cerebellar damage has been implicated in information processing speed (IPS) impairment associated with multiple sclerosis (MS) that might result from functional disconnection in the frontocerebellar loop. Structural alterations in individual posterior lobules, in which cognitive functioning seems preponderant, are still unknown. Our aim was to investigate the impact of grey matter (GM) volume alterations in lobules VI to VIIIb on IPS in persons with clinically isolated syndrome (PwCIS), MS (PwMS) and healthy subjects (HS). METHODS: 69 patients (37 PwCIS, 32 PwMS) and 36 HS underwent 3 T MRI including 3-dimensional T1-weighted MRIs. Cerebellum lobules were segmented using SUIT V.3.0 to estimate their normalised GM volume. Neuropsychological testing was performed to assess IPS and main cognitive functions. RESULTS: Normalised GM volumes were significantly different between PwMS and HS for the right (p<0.001) and left lobule VI (p<0.01), left crus I, right VIIb and entire cerebellum (p<0.05 for each comparison) and between PwMS and PwCIS for all lobules in subregions VI and left crus I (p<0.05). IPS, attention and working memory were impaired in PwMS compared with PwCIS. In the whole population of patients (PwMS and PwCIS), GM loss in vermis VI (R2=0.36; p<0.05 when considering age and T2 lesion volume as covariates) were associated with IPS impairment. CONCLUSIONS: GM volume decrease in posterior lobules (especially vermis VI) was associated with reduced IPS. Our results suggest a significant impact of posterior lobules pathology in corticocerebellar loop disruption resulting in automation and cognitive optimisation lack in MS. TRIAL REGISTRATION: Clinicaltrail NCT01207856, NCT01865357; Pre-results.




25/10/2016 | Mult Scler   IF 4.5
Hippocampal microstructural damage correlates with memory impairment in clinically isolated syndrome suggestive of multiple sclerosis.
Planche V, Ruet A, Coupe P, Lamargue-Hamel D, Deloire M, Pereira B, Manjon JV, Munsch F, Moscufo N, Meier DS, Guttmann CR, Dousset V, Brochet B, Tourdias T

Abstract:
OBJECTIVE: We investigated whether diffusion tensor imaging (DTI) could reveal early hippocampal damage and clinically relevant correlates of memory impairment in persons with clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS). METHODS: A total of 37 persons with CIS, 32 with MS and 36 controls prospectively included from 2011 to 2014 were tested for cognitive performances and scanned with 3T-magnetic resonance imaging (MRI) to assess volumetric and DTI changes within the hippocampus, whole brain volume and T2-lesion load. RESULTS: While there was no hippocampal atrophy in the CIS group, hippocampal fractional anisotropy (FA) was significantly decreased compared to controls. Decrease in hippocampal FA together with increased mean diffusivity (MD) was even more prominent in MS patients. In CIS, hippocampal MD was correlated with episodic verbal memory performance (r = -0.57, p = 0.0002 and odds ratio (OR) = 0.058, 95% confidence interval (CI) = 0.0057-0.59, p = 0.016 adjusted for age, gender, depression and T2-lesion load), but not with cognitive tasks unrelated to hippocampal functions. Hippocampal MD was the only variable discriminating memory-impaired from memory-preserved persons with CIS (area under the curve (AUC) = 0.77, sensitivity = 90.0%, specificity = 70.3%, positive predictive value (PPV) = 52.9%, negative predictive value (NPV) = 95.0%). CONCLUSION: DTI alterations within the hippocampus might reflect early neurodegenerative processes that are correlated with episodic memory performance, discriminating persons with CIS according to their memory status.




30/06/2016 | AJNR Am J Neuroradiol
Cervical Spinal Cord DTI Is Improved by Reduced FOV with Specific Balance between the Number of Diffusion Gradient Directions and Averages.
Crombe A, Alberti N, Hiba B, Uettwiller M, Dousset V, Tourdias T

Abstract:
BACKGROUND AND PURPOSE: Reduced-FOV DTI is promising for exploring the cervical spinal cord, but the optimal set of parameters needs to be clarified. We hypothesized that the number of excitations should be favored over the number of diffusion gradient directions regarding the strong orientation of the cord in a single rostrocaudal axis. MATERIALS AND METHODS: Fifteen healthy individuals underwent cervical spinal cord MR imaging at 3T, including an anatomic 3D-Multi-Echo Recombined Gradient Echo, high-resolution full-FOV DTI with a NEX of 3 and 20 diffusion gradient directions and 5 sets of reduced-FOV DTIs differently balanced in terms of NEX/number of diffusion gradient directions: (NEX/number of diffusion gradient directions = 3/20, 5/16, 7/12, 9/9, and 12/6). Each DTI sequence lasted 4 minutes 30 seconds, an acceptable duration, to cover C1-C4 in the axial plane. Fractional anisotropy maps and tractograms were reconstructed. Qualitatively, 2 radiologists rated the DTI sets blinded to the sequence. Quantitatively, we compared distortions, SNR, variance of fractional anisotropy values, and numbers of detected fibers. RESULTS: Qualitatively, reduced-FOV DTI sequences with a NEX of >/=5 were significantly better rated than the full-FOV DTI and the reduced-FOV DTI with low NEX (N = 3) and a high number of diffusion gradient directions (D = 20). Quantitatively, the best trade-off was reached by the reduced-FOV DTI with a NEX of 9 and 9 diffusion gradient directions, which provided significantly fewer artifacts, higher SNR on trace at b = 750 s/mm2 and an increased number of fibers tracked while maintaining similar fractional anisotropy values and dispersion. CONCLUSIONS: Optimized reduced-FOV DTI improves spinal cord imaging. The best compromise was obtained with a NEX of 9 and 9 diffusion gradient directions, which emphasizes the need for increasing the NEX at the expense of the number of diffusion gradient directions for spinal cord DTI contrary to brain DTI.




04/2016 | Stroke   IF 5.8
Early Fiber Number Ratio Is a Surrogate of Corticospinal Tract Integrity and Predicts Motor Recovery After Stroke.
Bigourdan A, Munsch F, Coupe P, Guttmann CR, Sagnier S, Renou P, Debruxelles S, Poli M, Dousset V, Sibon I, Tourdias T

Abstract:
BACKGROUND AND PURPOSE: The contribution of imaging metrics to predict poststroke motor recovery needs to be clarified. We tested the added value of early diffusion tensor imaging (DTI) of the corticospinal tract toward predicting long-term motor recovery. METHODS: One hundred seventeen patients were prospectively assessed at 24 to 72 hours and 1 year after ischemic stroke with diffusion tensor imaging and motor scores (Fugl-Meyer). The initial fiber number ratio (iFNr) and final fiber number ratio were computed as the number of streamlines along the affected corticospinal tract normalized to the unaffected side and were compared with each other. The prediction of motor recovery (DeltaFugl-Meyer) was first modeled using initial Fugl-Meyer and iFNr. Multivariate ordinal logistic regression models were also used to study the association of iFNr, initial Fugl-Meyer, age, and stroke volume with Fugl-Meyer at 1 year. RESULTS: The iFNr correlated with the final fiber number ratio at 1 year (r=0.70; P<0.0001). The initial Fugl-Meyer strongly predicted motor recovery ( approximately 73% of initial impairment) for all patients except those with initial severe stroke (Fugl-Meyer<50). For these severe patients (n=26), initial Fugl-Meyer was not correlated with motor recovery (R(2)=0.13; p=ns), whereas iFNr showed strong correlation (R(2)=0.56; P<0.0001). In multivariate analysis, the iFNr was an independent predictor of motor outcome (beta=2.601; 95% confidence interval=0.304-5.110; P=0.031), improving prediction compared with using only initial Fugl-Meyer, age, and stroke volume (P=0.026). CONCLUSIONS: Early measurement of FNr at 24 to 72 hours poststroke is a surrogate marker of corticospinal tract integrity and provides independent prediction of motor outcome at 1 year especially for patients with severe initial impairment.




01/2016 | Stroke   IF 5.8
Stroke Location Is an Independent Predictor of Cognitive Outcome.
Munsch F, Sagnier S, Asselineau J, Bigourdan A, Guttmann CR, Debruxelles S, Poli M, Renou P, Perez P, Dousset V, Sibon I, Tourdias T

Abstract:
BACKGROUND AND PURPOSE: On top of functional outcome, accurate prediction of cognitive outcome for stroke patients is an unmet need with major implications for clinical management. We investigated whether stroke location may contribute independent prognostic value to multifactorial predictive models of functional and cognitive outcomes. METHODS: Four hundred twenty-eight consecutive patients with ischemic stroke were prospectively assessed with magnetic resonance imaging at 24 to 72 hours and at 3 months for functional outcome using the modified Rankin Scale and cognitive outcome using the Montreal Cognitive Assessment (MoCA). Statistical maps of functional and cognitive eloquent regions were derived from the first 215 patients (development sample) using voxel-based lesion-symptom mapping. We used multivariate logistic regression models to study the influence of stroke location (number of eloquent voxels from voxel-based lesion-symptom mapping maps), age, initial National Institutes of Health Stroke Scale and stroke volume on modified Rankin Scale and MoCA. The second part of our cohort was used as an independent replication sample. RESULTS: In univariate analyses, stroke location, age, initial National Institutes of Health Stroke Scale, and stroke volume were all predictive of poor modified Rankin Scale and MoCA. In multivariable analyses, stroke location remained the strongest independent predictor of MoCA and significantly improved the prediction compared with using only age, initial National Institutes of Health Stroke Scale, and stroke volume (area under the curve increased from 0.697-0.771; difference=0.073; 95% confidence interval, 0.008-0.155). In contrast, stroke location did not persist as independent predictor of modified Rankin Scale that was mainly driven by initial National Institutes of Health Stroke Scale (area under the curve going from 0.840 to 0.835). Similar results were obtained in the replication sample. CONCLUSIONS: Stroke location is an independent predictor of cognitive outcome (MoCA) at 3 months post stroke.




01/09/2015 | Biol Psychiatry   IF 8.9
Neuronal Circuits for Fear Expression and Recovery: Recent Advances and Potential Therapeutic Strategies.
Dejean C, Courtin J, Rozeske RR, Bonnet MC, Dousset V, Michelet T, Herry C

Abstract:
Recent technological developments, such as single unit recordings coupled to optogenetic approaches, have provided unprecedented knowledge about the precise neuronal circuits contributing to the expression and recovery of conditioned fear behavior. These data have provided an understanding of the contributions of distinct brain regions such as the amygdala, prefrontal cortex, hippocampus, and periaqueductal gray matter to the control of conditioned fear behavior. Notably, the precise manipulation and identification of specific cell types by optogenetic techniques have provided novel avenues to establish causal links between changes in neuronal activity that develop in dedicated neuronal structures and the short and long-lasting expression of conditioned fear memories. In this review, we provide an update on the key neuronal circuits and cell types mediating conditioned fear expression and recovery and how these new discoveries might refine therapeutic approaches for psychiatric conditions such as anxiety disorders and posttraumatic stress disorder.




06/2015 | j neuroradiol
OFSEP, a nationwide cohort of people with multiple sclerosis: Consensus minimal MRI protocol.
Cotton F, Kremer S, Hannoun S, Vukusic S, Dousset V

Abstract:
Multiple sclerosis (MS) is most generally considered as a severe disease with high physical and mental risks of disability. Since the end of the 1990s, several high cost long-term disease-modifying treatments provided some clinical efficiency. However, patient's follow-up was needed for the detection and the assessment of their side-effects. The 'Observatoire francais de la sclerose en plaques' (OFSEP) project aims to improve the clinical, biological and imaging systematic longitudinal follow-up of patients. It should increase the quality, efficiency and safety of patients' care, with a unique opportunity of large scale, about 41,000 patients followed in 62 French centers using the European Database for Multiple Sclerosis (EDMUS) software. OFSEP is divided into three working groups (clinical, biological and imaging). The imaging working group defines standards for routine MRI follow-up in the whole cohort and contains three subgroups: acquisition, workflow, and data processing. A common and feasible brain and spinal cord acquisition protocol has been defined by the acquisition group, and accepted by the OFSEP steering and scientific committees. This protocol can be implemented in all French MRI centers. The major MRI manufacturers have agreed to provide the dedicated collection of sequences as an 'OFSEP box' with every software upgrade or new MRI machine. The new OFSEP protocol will provide a unique opportunity to study a population-based collection of data from people with MS.




06/2015 | j clin neurosci   IF 1.4
Magnetisation transfer parameters and stroke outcome.
Sibon I, Tourdias T, Felix S, Asselineau J, Bracoud L, Vivot A, Rouanet F, Renou P, Orgogozo JM, Dousset V

Abstract:
Our aim was to evaluate the association between magnetisation transfer imaging (MTI) parameters measured 30 to 45 days after a cerebrovascular insult and post-stroke functional outcome at the same time. MTI offers the opportunity to depict subtle microstructural changes in infarcted areas. The clinical significance of the heterogeneity of brain damage within ischaemic stroke lesions is unknown. We prospectively included 58 patients with acute middle cerebral artery stroke. Diffusion-weighted imaging was performed within 12 hours after onset and the final infarct was documented by MRI with fluid-attenuated inversion recovery (FLAIR) and MTI at 30 to 45 days follow-up. We evaluated the association between MTI histogram parameters and the clinical outcome assessed by dichotomised (threshold >2) modified rankin scale (mRS) using multivariable logistic regression models adjusted on baseline characteristics. In multivariable analyses, stroke outcome was mostly driven by initial National Institutes of Health Stroke Scale (odds ratio [OR]=1.23; 95% confidence interval [CI]=1.07-1.41; p<0.01) while after adjustment of initial stroke severity magnetisation transfer ratio peak position was the only MRI parameter associated with functional status at 30 to 45 days post-stroke (OR=0.86; 95% CI=0.75-0.98; p=0.02); lower peak position values associated with higher mRS. Conversely, stroke volume measured on FLAIR sequence was not associated with stroke prognosis (p=0.87). The intensity of microstructural changes within the infarct core measured at 30 to 45 days follow-up is independently associated with the functional status evaluated at the same time. MTI and related parameters could be used as surrogate markers of treatment response in stroke clinical trials.




04/2015 | j neuroradiol
Extensive acute toxic leukoencephalopathy induced by fludarabine: two months follow-up on brain MRI.
Crombe A, Alberti N, Gilles M, Guy A, De Roquefeuil E, Dousset V, Tourdias T

Abstract: