Cortical Changes After Mental Imagery Training Combined With Electromyography-Triggered Electrical Stimulation in Patients With Chronic Stroke

Background and Purpose-Paresis of the upper extremity after stroke is not effectively solved by existing therapies. We investigated whether mental imagery training combined with electromyogram-triggered electric stimulation improved motor function of the paretic upper extremity in patients with chronic stroke and induced cortical changes. Methods-Fourteen subjects with chronic stroke (>= 12 months) were randomly allocated to receive mental imagery training combined with electromyogram-triggered electric stimulation (n=7) or generalized functional electric stimulation (n=7) on the forearm extensor muscles of the paretic extremity in 2 20-minute daily sessions 5 days a week for 4 weeks. The upper extremity component of the Fugl-Meyer Motor Assessment, the Motor Activity Log, the modified Barthel Index, and F-18-fluorodeoxyglucose brain positron emission tomography were measured before and after the intervention. Results-The group receiving mental imagery training combined with electromyogram-triggered electric stimulation exhibited significant improvements in the upper extremity component of the Fugl-Meyer Motor Assessment after intervention (median, 7; interquartile range, 5-8; P<0.05), but the group receiving functional electric stimulation did not (median, 0; interquartile range, 0-3). Differences in score changes between the 2 groups were significant. The mental imagery training combined with electromyogram-triggered electric stimulation group showed significantly increased metabolism in the contralesional supplementary motor, precentral, and postcentral gyri (P-uncorrected < 0.001) after the intervention, but the functional electric stimulation group showed no significant differences. Conclusions-Mental imagery training combined with electromyogram-triggered electric stimulation improved motor function of the paretic extremity in patients with chronic stroke. The intervention increased metabolism in the contralesional motor-sensory cortex.