Dual-hemisphere Transcranial Direct Current Stimulation on Lower Limb Motor Functions After Stroke
Condition: Stroke
MeSH terms: Stroke
Study type: Interventional

Summary: 
      The aim of the present study is to evaluate the possible effect of using dual-tDCS combined
      with conventional physical therapy on lower limb function in stroke patients.
    

Detailed description: 
      Stroke is a leading cause of adult motor disability. The recovery of motor function after
      stroke is often incomplete, despite classical rehabilitation techniques. In the beginning of
      the 21th century, transcranial direct current stimulation (tDCS) was introduced as a
      non-invasive tool to reversibly modulate brain excitability in humans in which a device sends
      constant low direct current (DC) delivered to the area of interest through the electrodes.
      These findings have opened the way to the therapeutic use of the brain stimulation for
      stroke. Based on the polarity-specific effects, anodal tDCS increases cortical excitability
      and cathodal tDCS decreases cortical excitability. To change the cortical excitability, tDCS
      differs from other brain stimulation techniques such as transcranial magnetic stimulation
      (TMS) in that it does not cause action potentials in cortical neurons, but rather induces
      shifts in neuronal resting membrane potential . This is considered to induce a lesser or no
      risk of a seizure. Given its advantages such as non-invasiveness, painlessness, safety, and
      possible after-effects, tDCS rapidly become a therapeutic adjuvant in neurorehabilitation
      especially in stroke patients with motor deficits . A number of studies in healthy subjects
      and stroke patients have reported that tDCS-induced excitability changes are related to
      increase in the performance of motor tasks and motor skills learning, mainly upper limb
      functions Recenty, dual-hemisphere tDCS in which, excites one hemisphere using anodal
      stimulation and inhibits the other by cathodal stimulation has been described in healthy
      subjects to greater enhance hand motor learning compared to uni-hemisphere tDCS. The
      corresponding tDCS-induced changes were reported in imaging study to involve interhemispheric
      interactions . An increase in the excitability of unaffected hemisphere and an abnormally
      high interhemispheric inhibition (IHI) drive from intact to lesioned hemisphere have been
      widely reported after unilateral stroke. Dual-tDCS has been more recent used in
      rehabilitation aiming to reduce the inhibition exerted by the unaffected hemisphere on the
      affected hemisphere and restore the normal balance of the IHI. Dual-tDCS combined with
      training or simultaneous occupational/physical therapy has been reported to improve motor
      skill learning and functions of the paretic upper limb in chronic stroke patients .

      Lower-limb functions are commonly disordered after stoke, however, less study has focused the
      effect of tDCS on lower limb functions. A single session of anodal tDCS over the lower limb
      M1 has reported to acutely enhance the effect of motor practice of the paretic ankle, force
      production of the paretic knee extensors, and postural stability in chronic stroke patients.
      However, little is known about effects of dual-tDCS on lower limb in stroke patients. Only
      one recent study showed an improvement of walking speed immediately after a single session of
      dual-tDCS alone in sub-acute stroke patients .
    

Intervention name(s): Transcranial direct current stimulation
Intervention type(s): Device
Intervention description(s): Dual Active/sham tDCS will be applied over the leg motor area (M1) priori to conventional physical therapy (1 hours). Anodal on affected hemisphere, Cathodal on unaffected hemisphere. Each participant will complete two experiments (active/sham tDCS). The interval between two experiments is at least 48 hours. The two experiments will be performed in random order for each subject.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: dual tDCS; physical rehabilitation; lower limb functions