P153. Correlation of cortical inhibition and motor performance after mental training with the hand in patients after stroke

Abstract

Background Mental practice has been used in neurologic rehabilitation to improve motor performance. This study explored if mental practice targeting the hand modulates cortical excitability and improves function of the affected hand. Transcranial Magnetic Stimulation (TMS) was used to measure changes in the duration of the cortical Silent Period (cSP) and to analyze the amplitudes of motor evoked potentials (MEPs). Methods A number of 32 subacute stroke patients participated in the study (n = 32; m = 19, f = 13; mean age = 62.8 ± 11.2 years; time since onset = 2.1 ± 1.1 months). Mental practice for the hand consisted of two interventions. Intervention 1 comprises a 30 min computer based Hand Identification Task (HIT). Intervention 2 includes repeated mental performance of the Box-and-Block Test (BBT) over 30 min. Those two kinds of intervention were administered in randomized order on different days. Before and after training, cortical excitability of the motor system as well as motor performance of the hands were measured. TMS was executed with a round coil, with electrical recordings from the Interosseus dorsalis I muscle on both sides. The hemispheres were stimulated one after the other, with a stimulus intensity of 130% of the resting motor threshold. During TMS, the patients performed a tonic pinch grip. Duration of cSP and MEP amplitudes were analyzed taking the mean of 5 stimulations. Motor function data were gathered using the BBT and a subtest of Jebsen Taylor Hand Function Test (JTHFT; nine men’s morris game stone task). Results Independent of the kind of the intervention, the duration of cSP on the affected side was significantly shorter after intervention (p Conclusions Mental practice for the hand reduced cortical inhibition on the affected side and improved motor performance, independently of the kind of mental intervention. Thus, to occupy oneself mentally with the hand seems to be more important than the specificity of the intervention. The correlation between reduced inhibition and improved motor performance suggests that an indirect fostering of excitability by reducing the activity of inhibitory neurons can improve motor function.