Investigation of in-phase bilateral exercise effects on corticospinal plasticity in relapsing remitting multiple sclerosis: a multiple baseline design

Relapsing-remitting multiple sclerosis is the most common type of multiple sclerosis characterized by periods of relapses and generating various motor symptoms. These symptoms are associated with the corticospinal tract integrity, which is quantified by means of corticospinal plasticity which can be probed via transcranial magnetic stimulation and assessed with motor threshold, motor evoked potential and central motor conduction time. Several factors, such as exercise and interlimb coordination, can influence corticospinal plasticity. Previous work in healthy and in stroke patients showed that the greatest improvement in corticospinal plasticity occurred during in-phase bilateral arm exercises. Altered corticospinal plasticity due to bilateral cortical lesions is common in multiple sclerosis, yet, the impact of these type of exercises in this cohort is unclear. The aim of this concurrent multiple baseline design study is to investigate the effects of in-phase bilateral exercises on corticospinal plasticity and on clinical measures using transcranial magnetic stimulation and standardized clinical assessment, in five people with relapsing-remitting multiple sclerosis. The intervention protocol will last for 12 consecutive weeks (30-60 minutes /session x 3 sessions/week) and include in-phase bilateral movements of the upper limbs, adapted to different sports activities and to functional training. To define functional relation between the intervention and the results on corticospinal plasticity (i.e., resting motor threshold, motor evoked potential amplitude, latency) and on clinical measures (i.e., balance, gait, bilateral hand dexterity and strength, cognitive function), we will perform a visual analysis followed by multilevel modelling and the single case educational design-specific mean difference in order to estimate the magnitude of the effect size across cases. We assume that possible effects from our study, will introduce a type of exercise that will be effective during the disease progression.