Transcutaneous spinal cord stimulation (tSCS) is a promising noninvasive alternative to epidural stimulation. However, further studies are needed to clarify how tSCS affects postural control. The aim of this study was to investigate the effect of transcutaneous cervical spinal cord stimulation on postural stability in healthy participants via computerized stabilization. The center of pressure and the frequency spectrum of the statokinesiogram were assessed in 14 healthy volunteers under tSCS conditions with frequencies of 5 Hz or 30 Hz, subthreshold or suprathreshold stimulus strength, open or closed eyes, and hard or soft surfaces in various combinations. The results revealed that not all the changes in the center of the pressure oscillations reached statistical significance when the tSCS was used. However, tSCS at a frequency of 30 Hz with a suprathreshold stimulus strength improved postural stability. The use of subthreshold or suprathreshold tSCS at 5 Hz led to a shift of 60% of the signal power to the low-frequency range, indicating activation of the vestibular system. With tSCS at 30 Hz, the vestibular component remained dominant, but a decrease in the proportion of high-frequency oscillations was observed, which is associated with muscle proprioception. Thus, transcutaneous electrical stimulation of the cervical spinal cord may be an effective method for activating spinal cord neural networks capable of modulating postural control.

This study examined the effects of different sensory stimuli on postural control in healthy volunteers. The experimental conditions included standing with the eyes closed, standing on a compliant surface, transcutaneous electrical stimulation of the cervical spinal cord (tSCS) at 5 and 30 Hz and at different intensities (subthreshold and suprathreshold), and exposure to virtual reality (VR). Time–frequency analysis of stabilograms revealed increased high-frequency postural sway during standing with the eyes closed and on a compliant surface, indicating a greater contribution of somatosensory and proprioceptive inputs to balance control. tSCS at both frequencies tended to reduce sway amplitude irrespective of stimulation intensity. Viewing video sequences through a VR headset increased the statokinesiogram area and mean linear velocity, indicating postural instability. These findings indicate that changes in afferent input affect postural control mechanisms. tSCS appears to have a compensatory effect by promoting redistribution of the functional load across different levels of balance regulation, whereas VR enhances destabilizing effects when proprioceptive input is less reliable.