Transcranial Direct Current Stimulation and Walking in Multiple Sclerosis

Weakness on one side of the body is a hallmark of Multiple Sclerosis (MS), which has been determined to be a significant cause of progressive worsening of walking abilities. Currently, there are no efficient rehabilitation strategies available to target strength asymmetries and walking impairments. Many of the current treatments, including pharmaceuticals, are only mildly effective and are often very expensive. Thus, the development of practical, inexpensive, and effective adjunct treatments is needed. The study is to examine the efficacy of different tDCS protocols at improving walking in PwMS. Although the details of the studies slightly vary, the global aspects of the experimental procedures are identical with the exception that the tDCS stimulation parameter timing differs between the groups. The study will be double-blind, sham-controlled, randomized cross-over design. Maximal voluntary contractions (MVCs) of the right and left knee extensors, knee flexors, hip flexors, and dorsiflexors will be performed to determine the more-affected leg. The study compromises 2 groups of subjects which will attend the lab for three sessions. In the first session subjects will be consented, complete the PDDS, the Fatigue Severity Scale (FSS), and a 6 minute walk test (6-MWT) for baseline performance. The second session will involve a 6 MWT performed in association with 2 conditions. Group 1: DURINGtDCS, DURINGSHAM. Group 2: BEFOREtDCS, BEFORESHAM. The conditions in each group will be in a randomized order. Intensity of tDCS will be 2mA for both groups. Group 1 will receive the conditions during the 6 MWT. tDCS for 6 min has been shown to be sufficient to induce cortical excitability. Group 2 will receive 13 min of tDCS or sham, which results in after effects lasting through the completion of the 6 MWT. tDCS will be applied to the motor cortex (M1) corresponding to the more-affected leg either before or during the 6 min walk test