Structural plasticity of chronic stroke patients in the contra-lateral hemisphere

Objective: Recovery of function is one of the most important issues after a cerebral vascular incident and can be attributed to brain structural reorganization. However, there is an ongoing debate as to whether such reorganization can occur even in the hemisphere contralateral to the lesion site. In order to substantiate further evidence, we analyzed cortical thickness of patients that suffered from unilateral subcortical infarction.

Method: Patients diagnosed with left hemisphere middle cerebral artery infarction with lesions within lenticulostriatal arteries territory (n=7) and normal age-matched participants (n=34) were enrolled in the study. The VINCI software package (http://www.nf.mpg.de/vinci/) was used to visualize, trace, and create lesion-overlap maps. The Freesurfer software package (http://surfer.nmr.mgh.harvard.edu) was used in order to calculate right hemisphere cortical thickness, and group statistical analyses.

Results and discussion: When compared to a normal age-matched population, the patient group exhibits a significant (p<0,01) increase in cortical thickness essentially in sensorimotor cortical areas (posterior bank of the central sulcus, see hot colors in Fig.) and a decrease in pre-motor areas (see blue colors in Fig.). As the maximum lesion-overlap is restricted primarily to the putamen, we would argue a compensatory mechanism that is due to disconnection of the afferent fibers to the contralateral basal ganglia.