Four-week transcranial direct current stimulation combined with foot core exercise is associated with structural and functional changes in the sensorimotor network in individuals with chronic ankle instability

Chronic ankle instability (CAI) is a common disorder linked to altered sensorimotor function and increased risk of falls and injuries. Maladaptive changes in brain structure and function are recognized as key contributors to these deficits. It remains unclear whether intervention simultaneously targeting peripheral and supraspinal elements of sensorimotor regulation can modulate such altered structure and function in CAI. In this double-blinded, randomized, placebo-controlled trial, 31 CAI participants completed structural and functional MRI as well as ankle functional assessments before and immediately after four weeks of either transcranial direct current stimulation (tDCS) targeting primary sensorimotor cortex (three times per week; 12 sessions) (tDCS + FCE), or sham (i.e., control), in combination with foot core exercise (FCE), an exercise targeting the peripheral neuromuscular control (primarily the sensorimotor function of foot and ankle). Compared to the control, the tDCS + FCE group showed intervention-related increases in gray matter volume of sensorimotor network (SMN), and in the within-network functional connectivity and segregation of the SMN, as well as improved sensorimotor performance. These findings provide a conceptual framework supporting the benefits of interventions simultaneously targeting both peripheral and supraspinal elements for sensorimotor function, providing critical knowledge for optimizing the rehabilitative strategies for sensorimotor function in CAI. ChiCTR2500101914. Registered 6 May 2025- https://www.chictr.org.cn/ .