Article

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.

Langue : ANGLAIS