Abstract

Objective
To investigate therapeutic effects of anodal direct current (DC) polarization on the primary motor cortex in subacute and chronic stroke patients by measuring changes of hand function and corticospinal excitability before and after stimulation. Method: Fourteen subacute and chronic stroke patients were included in this study. This study was designed as a sham-controlled, double-blind, and crossover experiment. The anode was positioned on the primary motor cortex of the affected hemisphere. The primary motor cortex was identified using transcranial magnetic stimulation (TMS), the motor evoked potentials (MEPs) were recorded by surface electrodes placed over the contralateral first dorsal interosseous muscle. DC was delivered for 20 minute at 2 mA with 25 cm² saline-soaked sponge electrodes. Before and after DC polarization, we checked the box and block test, nine hole peg test, grip power, lateral prehension power, MEPs amplitude, and MEPs latency. Results: The box and block test, grip power, lateral prehension power, and MEPs amplitude increased after anodal DC to primary motor cortex (p＜0.05). Positive correlation showed between improvement of box and block test and change of MEPs amplitude (r=0.808, p=0.001). Conclusion: Increased hand functions and the corticospinal tract excitability were obtained by 2 mA, 20 minute anodal DC polarization. Anodal DC polarization to primary motor cortex may play a potential role for facilitating the corticospinal tract thereby enhancing hand motor recovery in stroke patients. (J Korean Acad Rehab Med 2009; 33: 259-264)

• Keywords: Tanscranial direct current stimulation, Motor cortex, Brain polarization, Hand function