Transcranial Direct Current Stimulation to Facilitate Lower Limb Recovery Following Stroke: Current Evidence and Future Directions

Abstract

Stroke remains a global leading cause of disability. Novel treatment approaches are required to alleviate impairment and promote greater functional recovery. One potential candidate is transcranial direct current stimulation (tDCS), which is thought to non-invasively promote neuroplasticity within the human cortex by transiently altering the resting membrane potential of cortical neurons. To date, much work involving tDCS has focused on upper limb recovery following stroke. However, lower limb rehabilitation is important for regaining mobility, balance, and independence and could equally benefit from tDCS. The purpose of this review is to discuss tDCS as a technique to modulate brain activity and promote recovery of lower limb function following stroke. Preliminary evidence from both healthy adults and stroke survivors indicates that tDCS is a promising intervention to support recovery of lower limb function. Studies provide some indication of both behavioral and physiological changes in brain activity following tDCS. However, much work still remains to be performed to demonstrate the clinical potential of this neuromodulatory intervention. Future studies should consider treatment targets based on individual lesion characteristics, stage of recovery (acute vs. chronic), and residual white matter integrity while accounting for known determinants and biomarkers of tDCS response.

The effects of robot-assisted gait training combined with non-invasive brain stimulation on lower limb function in patients with stroke and spinal cord injury: A systematic review and meta-analysis

“…In another study, the authors applied multi-channel electrodes (Otal et al, 2016 ). A computational modeling study that compared electrode placements targeting M1 (i.e., electrode placements for all studies included in this meta-analysis) and the cerebellum found that cerebellar stimulation produced substantially higher electric field strengths in the target area compared to M1 stimulation, suggesting that the cerebellum may indeed be a suitable target for tDCS (Gowan and Hordacre, 2020 ). Future tDCS studies should consider these factors.…”

“…Furthermore, as an example of rehabilitation in patients with lower limb motor paralysis, some studies have shown the effectiveness of non-invasive brain stimulation (NIBS), such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS). Multiple meta-analyses and systematic reviews have examined the efficacy of tDCS, rTMS, or spinal direct current stimulation on lower limb motor function related to gait and balance function in patients with stroke or SCI (Chieffo et al, 2016 ; Fleming et al, 2017 ; Li et al, 2018 ; Ghayour-Najafabadi et al, 2019 ; Tung et al, 2019 ; Abualait and Ibrahim, 2020 ; Elsner et al, 2020 ; Gowan and Hordacre, 2020 ). Although most meta-analyses have demonstrated the effectiveness of NIBS, some have shown limited effectiveness.…”

Driving Oscillatory Dynamics: Neuromodulation for Recovery After Stroke

“…The first use of tDCS to enhance stroke recovery in the acute phase (30 min after stroke induction) was in 2013, and the authors showed reduced lesion volume and improved neurological-severity scores in mice following cathodal stimulation to the sensorimotor cortex (Peruzzotti-Jametti et al, 2013). Anodal tDCS over the target brain area and the cathode placed over the contralateral region, has proved effective in improving both upper and lower limb impairments in stroke patients, as well as anxiety and depressive symptoms (Fusco et al, 2014;Allman et al, 2016;Fleming et al, 2017;Bornheim et al, 2020;Gowan and Hordacre, 2020). Beta coherence between the ipsilesional motor cortex and other brain regions increased in stroke patients who received cathodal tDCS over the contralesional primary motor cortex in the first 4 weeks after stroke, and this increase correlated with improved motor function (Nicolo et al, 2018).…”

Effect of Simultaneous High-definition Transcranial Direct Current Stimulation and Robot-assisted Gait Training on Gait Function in Chronic Stroke Patients

“…This cortical area is located in the medial part of the precentral gyrus deep within the interhemispheric ssure. Targeted application of tDCS to this area is more challenging than targeting the upper limbs [22]. High-de nition transcranial direct current stimulation (HD-tDCS) with smaller "high-de nition" electrodes has been proposed to improve the focus of the stimulation in the target area [23].…”