Split-Belt Training but Not Cerebellar Anodal tDCS Improves Stability Control and Reduces Risk of Fall in Patients with Multiple Sclerosis

Abstract

The objective of this study was to examine the therapeutic potential of multiple sessions of training on a split-belt treadmill (SBT) combined with cerebellar anodal transcranial direct current stimulation (tDCS) on gait and balance in People with Multiple Sclerosis (PwMS). Twenty-two PwMS received six sessions of anodal (PwMSreal, n = 12) or sham (PwMSsham, n = 10) tDCS to the cerebellum prior to performing the locomotor adaptation task on the SBT. To evaluate the effect of the intervention, functional gait assessment (FGA) scores and distance walked in 2 min (2MWT) were measured at the baseline (T0), day 6 (T5), and at the 4-week follow up (T6). Locomotor performance and changes of motor outcomes were similar in PwMSreal and PwMSsham independently from tDCS mode applied to the cerebellum (anodal vs. sham, on FGA, p = 0.23; and 2MWT, p = 0.49). When the data were pooled across the groups to investigate the effects of multiple sessions of SBT training alone, significant improvement of gait and balance was found on T5 and T6, respectively, relative to baseline (FGA, p < 0.001 for both time points). The FGA change at T6 was significantly higher than at T5 (p = 0.01) underlining a long-lasting improvement. An improvement of the distance walked during the 2MWT was also observed on T5 and T6 relative to T0 (p = 0.002). Multiple sessions of SBT training resulted in a lasting improvement of gait stability and endurance, thus potentially reducing the risk of fall as measured by FGA and 2MWT. Application of cerebellar tDCS during SBT walking had no additional effect on locomotor outcomes.

Effectiveness of transcranial direct current stimulation on balance and gait in patients with multiple sclerosis: systematic review and meta-analysis of randomized clinical trials

“…Eight studies [ 30 – 33 , 35 – 37 , 40 ] applied stimulation over M1, with the cathode placed over the supraorbital region or the shoulder region. The remaining three studies applied stimulation over the cerebellum, with the cathode placed on the buccinator muscle [ 34 , 38 , 39 ]. Five of the studies used electrode sizes of 25 cm 2 [ 30 , 32 , 33 , 35 , 37 ], four studies [ 34 , 38 – 40 ] used 35 cm 2 electrodes, and only two studies [ 31 , 36 ] used 16 cm 2 electrodes.…”

“…The current intensity varied between 1.5 mA and 2.5 mA. The applied current density ranged from 0.04 mA/cm 2 [ 34 ], 0.05 mA/cm 2 [ 38 , 40 ], 0.08 mA/cm 2 [ 30 , 35 , 37 , 39 ], 0.09 mA/cm 2 [ 36 ], 0.1 mA/cm 2 [ 32 , 33 ], to 1.5 mA/cm 2 [ 31 ], which was the highest current intensity used.…”

“…Workman et al used the shortest stimulation time of 13 min [ 30 ]. Two articles applied 15 min of stimulation [ 38 , 39 ]. One study applied stimulation for 25 min [ 36 ], and Oveisgharan et al used the longest stimulation time of 30 min [ 31 ].…”

“…This type of protocol has been described as effective for conducting double-blind clinical trials in neurorehabilitation [ 43 ]. Only two articles did not specify whether they used the initial ramp-up before disconnecting the current in the sham group [ 35 , 39 ].…”

“…The functional assessment of gait was the main variable measured in eight studies. In 6 studies, it was measured using the TUG test [ 32 , 33 , 35 – 39 ]. Two articles used validated gait assessment scales such as the 25FWT [ 31 ] and the 2MWT [ 33 ].…”