Bihemispheric Transcranial Direct Current Stimulation Acutely Improves Strength And Force Steadiness In Post-stroke Hemiparetic Patients

Abstract

Transcranial direct current stimulation (tDCS) has been applied within rehabilitation programs in post-stroke patients. Two approaches have been used to minimize inter-hemispheric unbalance: cathodal tDCS upon the contralesional hemisphere to reduce inhibition of the ipsilesional hemisphere, and anodal tDCS upon the ipsilesional hemisphere to increase its excitability. PURPOSE: The purpose of present study was to investigate whether bihemisferic tDCS in both ipsilesional and contralesional motor cortex modulate the maximal strength and force steadiness of lower limbs in chronic stroke patients. METHODS: In a double blind, crossover, randomized sham-controlled experimental design, 10 chronic stroke patients performed bilateral knee extension and flexion isokinetic tests at submaximal and maximal workloads [2 sets of 10 repetitions at 50% peak torque and 1 set of 3 reps at 100% peak torque, respectively] with and without bihemispheric tDCS. RESULTS: After tDCS the peak torque increased only for the knee extension in the non-paretic limb (P = 0.008), while no difference was found in the paretic limb (P > 0.05). The force steadiness reflected by the coefficient of variation during the extension phase of the knee extension decreased in tDCS vs. sham condition in both paretic (P = 0.01) and non-paretic limbs (P = 0.04). However, in the knee flexion phase, the coefficient of variation after tDCS decreased only in paretic limb (P = 0.05). CONCLUSION: A single session of bihemispheric tDCS might enhance the maximal strength and force steadiness in chronic stroke patients. These findings warrant additional research to ratify the potential role of bihemispheric tDCS to improve motor performance in stroke patients. Supported by Supported by the Brazilian Council for the Technological and Research Development (CNPq) and Carlos Chagas Foundation for the Research Development in the State of Rio de Janeiro (FAPERJ)