Activation changes in sensorimotor cortex during improvement due to CIMT in chronic stroke

Abstract

The integrity of the pyramidal tract (PT) does not seem to influence clinical improvement after two weeks of Constraint-Induced Movement Therapy (CIMT). However, when PT is intact, improvement is associated with a decrease of fMRI-activation in primary sensorimotor cortex (SMC) and when affected, with an increase of activation in SMC. The aim was to observe the long-term effect of CIMT, depending on the integrity of the PT, and to correlate improvement with changes in fMRI-activation. Twelve new chronic stroke patients were treated with CIMT and integrity of PT was measured with transcranial magnetic stimulation. Before therapy, after therapy, and after 6 months, changes in motor function were correlated with differential and percent fMRI signal changes. All patients improved after two weeks of therapy, but only those with intact PT maintained improvement after 6 months. When PT was intact, improvement correlated with first a decrease of activation in SMC and after 6 months with an increase. When PT was affected, improvement consistently correlated with an increase in a lateral extension of SMC. Percent changes of activation were surrounded by differential changes. An intact PT might be advantageous for lasting improvement after CIMT and subregions in the SMC seem to behave differently during recovery.