Can brain electric stimulation improve stroke recovery?

22.03.2016

Stroke is the leading cause of disability. Recovery  is aided by active movement training and new learning. Improving neural plasticity is expected to bring additional benefits. Transcranial direct current stimulation (tDCS) to the motor cortex is known to enhance excitability and facilitate motor learning in healthy individuals.

Two recent systematic reviews (Bastani, Jaberzadeh 2012,  Butler et al 2013) provided initial evidence for the use of ipsilesional anodal tDCS in chronic stroke.

Would combining motor training with anodal tDCS improve rehabilitation outcome?

Claire Allman and colleagues at Oxford report the results of a randomized, sham controlled , parallel  group study  in 24 patients at least 6 months after a first unilateral stroke not directly involving the primary motor cortex. 1191 patients were assessed for eligibility. 26 were randomized to receive either anodal tDCS or sham treatment. 24 completed the intervention.

Intervention:  During the intervention period, participants conducted daily, supervised one hour sessions of motor training program (GRASP) over 9 days. For the first 20 min of each session, tDCS electrodes were positioned on the participant’s scalp to deliver either brain stimulation via tDCS or sham treatment. Clinical assesments and MRI were done at multiple points.

Results

At 3 months, upper limb ability in patients receiving repeated sessions of anodal tDCS to the ipsilesional motor cor- tex  was significantly better compared to the sham-treated group when tDCS was paired with motor training.  Clinical improvements were associated with increased activation of ipsilesional motor cortical areas.Structural MRI revealed intervention-related increases in gray matter volume in cortical areas, including ipsilesional motor and premotor cortex after anodal tDCS but not sham treatment.

How is tCDS working ? Is it true recovery/ ie original pathways for movement being restored? or is it compensation only ? If it is improving learning through local disinhibition, is  this task specific or can this be generalised to non trained items? There are many unanswered questions.

Larger studies are needed to  identify patient  characteristics that would help clinicians to  spot who would benefit from this intervention.

Conclusion: 

tCDS is showing promising benefits in stroke rehabilitation.

Summary of the article

Ipsilesional anodal tDCS enhances the functional benefits of rehabilitation in patients after stroke. Claire Allman, Ugwechi Amadi Anderson M. Winkler, Leigh Wilkins,Nicola Filippini Udo Kischka,Charlotte J. Stagg,Heidi Johansen-Berg.www.ScienceTranslationalMedicine.org 16 March 2016 Vol 8 Issue 330 330re1.

 

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