Neurodégénérescence secondaire de la substance noire après un infarctus touchant le striatum : évaluation par relaxométrie R2*

Abstract : Purpose: to demonstrate that long-term neurodegeneration of substantia nigra (SN) secondary to disconnection by a supratentorial infarct can be quantified with iron-sensitive imaging and contributes independently to patient outcome. Materials and Methods: 181 stroke patients (75 striatum infarcts, 106 other locations) were prospectively evaluated at 24-to-72h (baseline) and at one-year (follow-up) clinically and with MRI to quantify iron through R2* map. SN was outlined to measure an asymmetry index (SN-AI) of R2*. We focussed on the 95th percentile as a metric of high iron content. SN-AI95 was compared according to infarct location with unpaired t-test and with voxel-based analysis from average maps. SN-AI95 was also regressed with variables expected to influence iron accumulation. We also identified individual voxels whose infarction was significantly associated with high SN-AI95 through voxel-based lesion-symptom mapping (VLSM). Multiple regression models tested the association between SN-AI95 and clinical scores. Results: visual inspection, SN-AI95 and average maps consistently showed a delayed increase (at follow-up but not at baseline) that was significantly higher if ipsilateral striatum was involved than if not (p<0.0001). VLSM confirmed that striatum but also insula, internal and external capsules were associated with high SNAI95. This association was independent of infarct volume, baseline SN-AI95, microbleed, age and gender (β=4.99 [2.94; 7.04], p< 0.0001). Such increase of SN-AI95 was an independent contributor of poor motor outcome (Box-and-Block, p=0.01) but not of cognitive or emotional outcome. Conclusion: long-term neurodegeneration of SN remote from an ipsilateral infarct can be quantified with R2* and independently impacts motor outcome at follow-up.
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Master Thesis
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Submitted on : Tuesday, April 2, 2019 - 4:46:13 PM
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Pierre-Antoine Linck. Neurodégénérescence secondaire de la substance noire après un infarctus touchant le striatum : évaluation par relaxométrie R2*. Médecine humaine et pathologie. 2018. ⟨dumas-02088239⟩

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