A functional MRI study of the brain in stroke patients with upper-limb paralysis treated with constraint-induced movement therapy

Objective: To investigate and compare the activation patterns of stroke patients with upper-limb paralysis using functional MRI before and after treatment with constraint-induced movement therapy (CIMT) so as to explore the mechanism of CIMT. Methods: Six patients in chronic stage of brain infarction who have functional disturbance in right upper-limb and 9 normal controls were entered into the study. All of the patients were asked to perform the thumb-to-index finger tapping task and underwent functional MRI before and two weeks after CIMT. The controls underwent fMRI of same protocol once. The patients' upper-limb function scores before and after CIMT were analyzed with SPSS 11.5 by paired t test. The fMRI data were analyzed with analysis of functional neurolmages (AFNI) software. The percentage of blood oxygenation level dependent (BOLD) signal change for the normal control was analyzed by one-sample t test to indentify the activated brain regions. The percentage change of BOLD signal for the patients before and after CIMT was compared to control's data by independent-samples t test. The percentage change of BOLD signal for the patients before and after CIMT was analyzed by paired-samples t test. The significant difference level was set P<0.05. Results: The fMRI showed the patients' activated brain regions before CIMT were similar to that of the controls', while the activation level was lower. There were wide areas activated to compensate the impaired function especially for the fight upper-limb. Before CIMT, the patients' score for fight upper-limb on the action research arm test was 27±4. After CIMT, the patients' score was 40±3, and the difference was significant (t=14.626, P<0.05), which indicated the improved function. These subjects also displayed cortical reorganization after CIMT on fMRI. The areas responsible for the right hand movement showed increased activation and the activation level at bilateral corpora striata thalami, and cerebella increased. There were also activated regions in the contralateral parietal lobe. Conclusions: CIMT can improve the patients' upper-limb function effectively. The constraint-induced movement of the affected arm during CIMT appears to induce cortical reorganization and compensation as measured by fMRI. (authors)