Effects of Transcutaneous Electrical Nerve Stimulation on Cognitive Function and Upper Limb Motor Function in People With Chronic Stroke

The participants in Group A will receive tSCS (Burst mode, 9 pulses per burst, pulse frequency = 160 Hz, burst frequency = 2 Hz) with upper limb exercises. The electrical stimulation will be generated by the neurostimulator (MH8000P; MEDIHIGHTEC MEDICAL CO., LTD., Taiwan). Two 7.5 × 12.6 cm electrodes will be attached between C6 and T5 level on each side of spinal column and with 2 cm from the spine. Intensity of TENS will be individually selected by the participants according to tolerance levels.

The participants in Group B will receive tVNS (pulse frequency = 25Hz, pulse duration = 0.3 ms) on the cymba conchae of left outer ear with upper limb exercises.The electrical stimulation will be generated by the neurostimulator (MH8000P; MEDIHIGHTEC MEDICAL CO., LTD., Taiwan). Intensity of tVNS will be individually selected by the participants according to tolerance levels. Previous studies showed that it was effective to improve the upper limb motor function in people with stroke and cognitive function in people with mild cognitive function.

The participants in Group C will receive placebo tSCS and tVNS with upper limb exercises, where the stimulation will be delivered by placebo-TENS device with disconnected electrical circuit.