Brain reorganization following upper limb motor rehabilitation in patients with multiple sclerosis

Background: Motor rehabilitation has the target to maintain the residual capacities of the affected individuals to the highest possible level. Consistent data on its efficacy on functional brain reorganization are lacking. Brain adaptation is demonstrated to occur following damage in patients with multiple sclerosis (PwMS), and an efficient motor rehabilitation might interfere with this process. Aims: In this work, we investigated the effects of upper limb motor improvements due to a rehabilitative treatment on possible changes in brain activity patterns in PwMS. Methods: Thirty PwMS were included in this study and received an active (AMT group, 15 patients) or passive motor rehabilitation treatment (PMT group, 15 patients). AMT and PMT groups underwent 20 one-hour treatment sessions, three times a week. The AMT group underwent a rehabilitative treatment based on voluntary task-oriented exercises with the overall goal to improve activities of daily living. Conversely, the PMT group was treated with passive mobilization of the shoulder, elbow, wrist and hand of both limbs. Before and after the treatment, each patient was evaluated by standard evaluation protocols for upper limb motor performance and a sensor-engineered glove to quantify finger motor performance accuracy. In the same sessions, brain activity was investigated by functional magnetic resonance imaging (fMRI) during sequences of finger opposition movements with the right hand following a metronome tone set at 2 Hz; concomitant motor performance was recorded by an MR-compatible engineered glove. Results: Unimanual finger motor performance significantly improved in both groups as an effect of motor rehabilitation. At baseline, during right hand movements both groups activated the left sensorimotor areas, cerebellum bilaterally, and right frontal and parietal areas. After the treatment, fMRI showed a reduction of activation in the left sensorimotor areas and right supplementary motor area (areas not activated in healthy subjects for the same task and thought to be ‘compensatory’) in the AMT but not in the PMT group. In particular, the AMT group showed activations only in the left hemisphere (BA 3, 4, 6, 40), while in the PMT group activations in the right BA 6 and left cerebellum were also found. Conclusions: We can conclude that a greater benefit seems to be induced by the active motor treatment, which was found to reduce brain resource demand, normally altered by the disease course.