title: Single session of dual-tDCS transiently improves precision grip and dexterity of the paretic hand after stroke.
abstract: BACKGROUND
  After stroke, deregulated interhemispheric interactions influence residual paretic hand function. Anodal or cathodal transcranial direct current stimulation (tDCS) can rebalance these abnormal interhemispheric interactions and improve motor function.
  
  
  OBJECTIVE
  We explored whether dual-hemisphere tDCS (dual-tDCS) in participants with chronic stroke can improve fine hand motor function in 2 important aspects: precision grip and dexterity.
  
  
  METHODS
  In all, 19 chronic hemiparetic individuals with mild to moderate impairment participated in a double-blind, randomized trial. During 2 separate cross-over sessions (real/sham), they performed 10 precision grip movements with a manipulandum and the Purdue Pegboard Test (PPT) before, during, immediately after, and 20 minutes after dual-tDCS applied simultaneously over the ipsilesional (anodal) and contralateral (cathodal) primary motor cortices.
  
  
  RESULTS
  The precision grip performed with the paretic hand improved significantly 20 minutes after dual-tDCS, with reduction of the grip force/load force ratio by 7% and in the preloading phase duration by 18% when compared with sham. The dexterity of the paretic hand started improving during dual-tDCS and culminated 20 minutes after the end of dual-tDCS (PPT score +38% vs +5% after sham). The maximal improvements in precision grip and dexterity were observed 20 minutes after dual-tDCS. These improvements correlated negatively with residual hand function quantified with ABILHAND.
  
  
  CONCLUSIONS
  One bout of dual-tDCS improved the motor control of precision grip and digital dexterity beyond the time of stimulation. These results suggest that dual-tDCS should be tested in longer protocols for neurorehabilitation and with moderate to severely impaired patients. The precise timing of stimulation after stroke onset and associated training should be defined.
authors.affiliation: 1Université Catholique de Louvain (UCL), Yvoir, Belgium.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Lefebvre
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Thonnard
authors.forename: Patrice
authors.initials: P
authors.lastname: Laloux
authors.forename: André
authors.initials: A
authors.lastname: Peeters
authors.forename: Jacques
authors.initials: J
authors.lastname: Jamart
authors.forename: Yves
authors.initials: Y
authors.lastname: Vandermeeren
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D004558:Electric Stimulation; D005260:Female; D006225:Hand / Q000503:physiopathology*; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000503:physiopathology / Q000628:therapy*; D020521:Stroke / Q000503:physiopathology*
keywords: Purdue Pegboard Test; precision grip; repetitive transcranial magnetic stimulation; stroke rehabilitation; transcranial direct current stimulation