Article

Abnormal task-related activation in primary motor cortices (M1) has
been consistently found in functional imaging studies of subcortical stroke.
Whether the abnormal activations are associated with neuronal alterations in the
same or homologous area is not known. Objective. Our goal was to establish the
relationships between M1 measures of motor-task-related activation and a neuronal
marker, N-acetylaspartate (NAA), in patients with severe to mild hemiparesis.
Methods. A total of 18 survivors of an ischemic subcortical stroke (confirmed on
T2-weighted images) at more than six months post-onset and 16 age- and
sex-matched right-handed healthy controls underwent functional MRI during a
handgrip task (impaired hand in patients, dominant hand in controls) and proton
magnetic resonance spectroscopy (1H-MRS) imaging. Spatial extent and magnitude of
blood oxygen level-dependent response (or activation) and NAA levels were
measured in each M1. Relationships between activation and NAA were determined.
Results. Compared with controls, patients had a greater extent of contralesional
(ipsilateral to impaired hand, P < .001) activation and a higher magnitude of
activation and lower NAA in both ipsilesional (P = .008 and P < .001,
respectively) and contralesional (P < .0001, P < .05) M1. There were significant
negative correlations between extent of activation and NAA in each M1 (P = .02)
and a trend between contralesional activation and ipsilesional NAA (P = .08) in
patients but not in controls. Conclusions. Our results suggest that after stroke
greater neuronal recruitment could be a compensatory response to lower neuronal
metabolism. Thus, dual-modality imaging may be a powerful tool for providing
complementary probes of post-stroke brain reorganization.
CI - (c) The Author(s) 2013.

Langue : ANGLAIS