Transcutaneous Spinal Cord Stimulation Disrupts Conscious Ankle Proprioception and Produces a More Constrained Locomotor Pattern in Unimpaired Adults

2026-08-06

AI Summary

This study investigates the effects of transcutaneous spinal cord stimulation (tSCS) on ankle joint proprioceptive awareness and gait control in healthy adults. Combining acute and training intervention protocols with a bilateral robotic dynamic ankle positioning task (Crisscross), maximal dorsiflexion strength assessment, and multidimensional gait analysis—including spatiotemporal parameters, trunk sway, and center-of-mass displacement—the research reveals for the first time that tSCS disrupts conscious proprioception while inducing direction-dependent gait reorganization. Acute tSCS significantly increased proprioceptive error and constrained gait performance. Following training, proprioceptive function improved and the gains persisted; sagittal-plane gait not only recovered but surpassed baseline levels, whereas coronal-plane gait remained restricted. These findings demonstrate that the nervous system can adapt to aberrant afferent input through targeted training.

Abstract

Transcutaneous spinal cord stimulation (tSCS) modulates spinal sensorimotor circuits primarily through activation of afferent networks. While prior work has emphasized locomotor performance and spinal excitability, how tSCS affects conscious proprioceptive perception and the extent to which such effects parallel changes in locomotor control remain unclear. We investigated the acute and training-related effects of tSCS on ankle proprioception and gait in unimpaired adults (n = 14), with an independent control group (n = 14) completing identical proprioceptive training without stimulation. Proprioception was quantified using a bilateral robotic assessment of dynamic ankle localization ability (Crisscross), gross motor output using maximum dorsiflexion strength, and gait during normal and tandem treadmill walking using spatiotemporal, trunk-sway, and mediolateral center-of-mass (CoM) excursion measures. Acute tSCS increased ankle proprioceptive error (p < 0.001) while dorsiflexion strength was unchanged (p = 0.30). Gait shifted toward a modestly more constrained locomotor pattern, characterized by reduced step width and ML CoM excursion (p < 0.05). With continued training under stimulation, proprioceptive error decreased and, unlike the control group, the tSCS group showed progressive improvement that persisted after stimulation ended. Sagittal-plane gait measures recovered toward or beyond baseline, whereas mediolateral measures remained constrained, revealing a direction-dependent reorganization of locomotor control. Together, these findings show that tSCS influences multiple aspects of the sensorimotor control loop, disrupting conscious proprioception while reshaping locomotor behavior, and that the nervous system can adapt to altered afferent input through training.

Problem

• transcutaneous spinal cord stimulation
• proprioception
• locomotor control
• sensorimotor integration
• ankle

Innovation

• transcutaneous spinal cord stimulation
• proprioception
• locomotor control
• sensorimotor adaptation
• gait reorganization