Cerebellar tDCS and Balance Training in PwMS

The Effects of 2 mA and 4 mA Cerebellar Transcranial Direct Current Stimulation and Balance Training to Reduce Fall Risk in People With Multiple Sclerosis

Many people with multiple sclerosis (PwMS) have decreased balance and postural control, gait deficits, and a high frequency of falls. High fall rates and mobility impairments pose a significant risk to the independence and quality of life of PwMS. Therefore, effective interventions to improve balance and postural control are urgently needed to decrease the frequency of falls in PwMS. Balance training has been demonstrated to significantly improve postural control and gait in PwMS. One possible treatment modality to amplify the effects of balance training is transcranial direct current stimulation (tDCS), a non-invasive means to increase cortical excitability and potentially prime the brain for task specific learning. The cerebellum plays a vital role in balance and posture and may be an important target structure for tDCS studies seeking to reduce fall risk. Studies have shown that anodal cerebellar tDCS is effective in improving balance control in older adults with high fall risk and patients with chronic stroke. However, the most effective tDCS intensity and the duration of the effects on balance control has not been established. Moreover, no study has combined cerebellar tDCS and balance training to reduce fall risk in PwMS. The purpose of this study is to investigate the effects of cerebellar transcranial direct current stimulation (tDCS) on fall risk in people with relasping-remitting multiple sclerosis. We will conduct tDCS or SHAM followed by balance training on 4 consecutive days. We will evaluate fall risk with well-established functional tasks, such as the Berg Balance Scale, Timed Up and Go (TUG), the six minute walk test (6MWT), and static posturography. Prospective participants, men and women with relasping-remitting MS, will be recruited. To accomplish this study, 30 participants will be randomly assigned into 3 groups (2 mA tDCS, 4 mA tDCS, or SHAM). This study involves 4 daily visits at the Integrative Neurophysiology Lab at the same time of day for each subject and three follow-up visits. The duration of visit 1 will be approximately 2.5 hours and the duration of visits 2-4 will be approximately 1.5 hours. Visit 5, 6, and 7 will be approximately 24 hours, 1 week, and 3 weeks, respectively, after visit 4 and will last approximately 1.5 hours. During tDCS sessions, participants will undergo either Sham, 2 mA, and 4 mA tDCS for 20 minutes followed by balance training.

The tDCS device will perform a 30 second ramp up to 2 mA and then an immediate 30 second ramp down to 0 mA. Until the 19:30 minute time point, the tDCS will remain at 0 mA. At this time point, the tDCS will ramp up to 2 mA and then will immediately ramp back down to 0 mA.

The participants in this group will receive tDCS at 2 mA while seated comfortably. The intensity will start at 0 mA and will be incrementally increased to the target intensity (2 mA) over the initial 30 seconds. Then, the tDCS will deliver stimulation at the target intensity until the 19:30 minute time point. At this point, the current will gradually decrease back to 0 mA.

The participants in this group will receive tDCS at 4 mA while seated comfortably. The intensity will start at 0 mA and will be incrementally increased to the target intensity (4 mA) over the initial 30 seconds. Then, the tDCS will deliver stimulation at the target intensity until the 19:30 minute time point. At this point, the current will gradually decrease back to 0 mA.

tDCS is a non-invasive brain stimulation technique in which a very weak electrical current (2 mA) is applied to the scalp at the beginning of the session and then remains at 0 mA for the duration of the session to control for placebo-like effects. The anode and cathode will both be placed over the cerebellum.

The balance training protocol will include balance training exercises on both compliant (i.e., foam pad and trampoline) and firm surfaces.

tDCS is a non-invasive brain stimulation technique in which very weak electrical current (2 mA) is applied to the scalp for 20 minutes. The anode and cathode will both be placed over the cerebellum.

tDCS is a non-invasive brain stimulation technique in which very weak electrical current (4 mA) is applied to the scalp for 20 minutes. The anode and cathode will both be placed over the cerebellum.

Scale that examines the severity of fatigue and the impact on the participant's activities. There are nine statements about the participant's fatigue over the last week. They are asked to rate the severity on a scale from 1 to 7 (1 disagree, 7 agree) for each question.

Questionnaire to determine self-reported disability in people with multiple sclerosis. People are asked to choose one out of nine options that best describes how well they walk. 0 is "normal" and 8 is "bedridden."

Inclusion Criteria: medically diagnosed with relasping-remitting multiple sclerosis 18-70 years of age moderate disability (score of 2-6 on the Patient Determined Disease Scale [PPDS]) self-reported differences in function between legs, have fallen within the last year able to walk for 6 mins, and not taking any psychoactive medication. Exclusion Criteria: relapse within the last 60 days have changed disease modifying medications in the last 45 days are currently pregnant have a concurrent neurological or neuromuscular disease have been hospitalized within the last 90 days have any contraindications for the tDCS device (i.e., pacemakers or metal implants) are unable to understand/sign the consent form.