Thalamic alterations remote to infarct appear as focal iron accumulation and impact clinical outcome.
Brain. 2017-05-25; 140(7): 1932-1946
DOI: 10.1093/brain/awx114
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1. Brain. 2017 Jul 1;140(7):1932-1946. doi: 10.1093/brain/awx114.
Thalamic alterations remote to infarct appear as focal iron accumulation and
impact clinical outcome.
Kuchcinski G(1), Munsch F(2)(3), Lopes R(1), Bigourdan A(2), Su J(4), Sagnier
S(5), Renou P(5), Pruvo JP(1), Rutt BK(4), Dousset V(2)(3), Sibon I(5), Tourdias
T(2)(3).
Author information:
(1)University of Lille, CHU Lille, Department of Neuroradiology, F-5900 Lille,
France.
(2)University of Bordeaux, CHU de Bordeaux, Neuroimagerie Diagnostique et
Thérapeutique, F-33076 Bordeaux, France.
(3)INSERM, U1215, Neurocentre Magendie, F-33076 Bordeaux, France.
(4)Richard M. Lucas Center for Imaging, Radiology Department, Stanford
University, Stanford, CA 94305-5488, USA.
(5)University of Bordeaux, CHU de Bordeaux, Unité neurovasculaire, F-33076
Bordeaux, France.
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.
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DOI: 10.1093/brain/awx114
PMID: 28549087 [Indexed for MEDLINE]