Active prosthesis dependent functional cortical reorganization following stroke.

The present study investigated the neural correlates associated with gait improvements triggered by an active prosthesis in patients with drop-foot following stroke during the chronic stage. Eleven patients took part in the study. MEG recordings in conjunction with somatosensory stimulation of the left and right hand as well as gait analyses were performed shortly before or after prosthesis implantation surgery and 3-4 months later. Plastic changes of the sensorimotor cortex of the ipsi- and contralesional hemisphere were revealed. Gait analysis indicated that all patients improved their gait with the active prosthesis. Patients with larger plastic changes within the lesioned hemisphere maintained their improved gait performance even when the prosthesis was turned off. Patients with larger contralesional changes also improved their gait with the active prosthesis. However, their gait measures decreased when the prosthesis was turned off. The current data provide the neural basis of gait improvement triggered by an active prosthesis and has important implications with respect to the choice of the type of active prosthesis (implantable vs removable) and to the selection procedure of the patients (length of testing period).