Connectivity plasticity in the uninjured hemisphere after stroke has been reported in a number of experimental [1,2] and human [3-5]studies. Recently, we used Diffusion Spectrum Imaging (DSI) to explore longitudinal changes in the contra-lateral motor network of patients who sufferedfrom stroke [6] and we showed that contra-lateral motor tracts changes in Generalized Fractional Anisotropy (GFA) correlated strongly with clinicalscores. Furthermore, GFA measured in the acute phase together with a routine motor score and age proved to be strong predictors of motor outcome atsix months (r2=0.96, p=0.0002) [6]. Whether the observed changes in GFA are due to axonal remodeling or myelin plasticity remains however an openissue. GFA is the standard deviation of the diffusion process along different diffusion directions, representing fibre trajectories in tractographyreconstructions [7]. Like Fractional Anisotropy, GFA can be influenced by axonal integrity and, to a lesser extent, by the properties of intra-axonaltransport and myelin [8]. In this context, we wanted to study the behaviour of the Magnetisation Transfer Ratio (MTR) in the contra-lateral motor networkand to correlate it to the longitudinal changes in GFA [6]. The MTR is a semi-quantitative parameter which increases with the content of myelin and thedecreasing of water content along axonal fibers.
Myelin plasticity does not significantly influence diffusion remodelling in the uninjured motor network after stroke
Lin, YING CHIA;DADUCCI, Alessandro;MENEGAZ, Gloria;
2013-01-01
Abstract
Connectivity plasticity in the uninjured hemisphere after stroke has been reported in a number of experimental [1,2] and human [3-5]studies. Recently, we used Diffusion Spectrum Imaging (DSI) to explore longitudinal changes in the contra-lateral motor network of patients who sufferedfrom stroke [6] and we showed that contra-lateral motor tracts changes in Generalized Fractional Anisotropy (GFA) correlated strongly with clinicalscores. Furthermore, GFA measured in the acute phase together with a routine motor score and age proved to be strong predictors of motor outcome atsix months (r2=0.96, p=0.0002) [6]. Whether the observed changes in GFA are due to axonal remodeling or myelin plasticity remains however an openissue. GFA is the standard deviation of the diffusion process along different diffusion directions, representing fibre trajectories in tractographyreconstructions [7]. Like Fractional Anisotropy, GFA can be influenced by axonal integrity and, to a lesser extent, by the properties of intra-axonaltransport and myelin [8]. In this context, we wanted to study the behaviour of the Magnetisation Transfer Ratio (MTR) in the contra-lateral motor networkand to correlate it to the longitudinal changes in GFA [6]. The MTR is a semi-quantitative parameter which increases with the content of myelin and thedecreasing of water content along axonal fibers.
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