Stochastic galvanic vestibular stimulation improves kinetic performance in adolescent idiopathic scoliosis during obstacle negotiation.

Abstract

Vestibular dysfunction has been reported as a potential cause in adolescent idiopathic scoliosis (AIS). However, it remained unclear how stochastic galvanic vestibular stimulation (GVS) affected kinetic performance of patients with AIS. This study aimed to investigate the effect of stochastic GVS on ground reaction forces (GRF) measures during obstacle negotiation among patients with AIS. Fifteen patients with AIS and 15 age/sex-matched healthy controls (HC) participated in this study. Stochastic GVS was applied via electrodes placed over bilateral mastoid process with the intensity of 80% of individual sensory thresholds. Six walking trials including 2 types of GVS (stochastic GVS/sham stimulation) and 3 obstacle conditions (Level/Low/High) were randomly allocated to each participant, and each trial was repeated 3 times. Four AMTI force plates were used to measure GRF peaks and impulses in anterior-posterior (AP₁/AP₂), medial-lateral (ML₁/ML₂), and vertical (V₁/V₂) directions. Significant interactions were observed in AP₁ (F_2,56=3.537, p = 0.036), V₁ (F_2,56=4.118, p = 0.021), ML₁ (F_2,56=3.313, p = 0.044) and medial-lateral impulses (F_2,56=4.386, p = 0.017) for the step negotiating obstacles. Post-hoc comparisons showed that in comparison to sham stimulation, the application of stochastic GVS significantly (1) increased AP₁ (Low: p = 0.038) and V₁ (Low: p < 0.001; High: p = 0.035) in two groups; (2) decreased ML₁ of two groups (AIS: ps < 0.01; HC: ps < 0.05) and medial-lateral impulses in patients with AIS (Low: p = 0.013; High: p = 0.015) during obstacle negotiation. Additionally, the rates of change in ML₁ and medial-lateral impulses among patients with AIS were significantly higher than that of HC, indicating that stochastic GVS demonstrated a greater effect of decreasing ML₁ and medial-lateral impulses in AIS. Stochastic GVS ameliorated kinetic performance of patients with AIS during obstacle negotiation, and its potential mechanism may involve the induction of stochastic resonance phenomenon to enhance vestibular perception. Our study offered stochastic GVS as a novel approach to target vestibular-related postural instability in AIS.