Impact of Virtual Reality Alone and in Combination with Conventional Therapy on Balance in Parkinson's Disease: A Systematic Review with a Meta-Analysis of Randomized Controlled Trials.

Background and Objectives: Virtual reality (VR)-based interventions provide immersive and interactive environments that can enhance motor learning and deliver real-time feedback, offering potential advantages over conventional therapies. This systematic review evaluated the impact of non-immersive and immersive VR exergaming interventions versus conventional therapy on balance in Parkinson's disease (PD) through a detailed analysis of randomized controlled trials (RCTs). Materials and Methods: A comprehensive search was conducted across the PubMed, Lilacs, IBECS, CENTRAL, Web of Science (WOS), EBSCOHost, and SciELO databases. Article selection and duplicate removal were managed using Rayyan QCRI. The quality of the evidence was assessed using the GRADE system. Results: From an initial screening of 100 studies, 58 underwent title and abstract screening. After full-text evaluation, 11 RCTs met the inclusion criteria, involving 518 participants with PD (average age: 67.3 years; 67.95% men). The balance outcomes were primarily measured using the Berg balance scale (BBS), employed in most studies (n = 9). The pooled analysis demonstrated a significant improvement in the balance scores for the experimental groups compared to the controls, with a standardized mean difference (SMD) of 0.58 [95% CI: 0.07, 1.09, p = 0.03]. However, the heterogeneity was substantial (I² = 77%). The analysis of the six-minute walking test (6 MWT), as another outcome of four articles, revealed a mean difference of 32.99 m [95% CI: -8.02, 74.00], but the effect was not statistically significant (p = 0.11). The heterogeneity for this outcome was moderate (I² = 41%), indicating some variability across studies. Alternative tools, such as the Tinetti Performance-Oriented Mobility Assessment (POMA) scale, the UPDRS III, and the sensory organization test (SOT), were also evaluated where possible. Conclusions: VR-based interventions offer promise for improving balance in Parkinson's disease, enhancing rehabilitation engagement. Their integration into clinical practice could complement conventional therapy. However, further research is needed to optimize protocols, standardize parameters, and maximize their impact on mobility, independence, and quality of life.