Effectiveness of deep brain stimulation in improving balance in Parkinson's disease: A systematic review and meta-analysis.

INTRODUCTION: Balance dysfunction is a debilitating feature of advanced Parkinson's disease (PD), potentially improved by deep brain stimulation (DBS). This systematic review and meta-analysis pooled evidence from randomized controlled trials (RCT) on DBS effectiveness in improving balance in PD.

METHODS: A systematic search was conducted to identify eligible RCTs investigating the effectiveness of DBS on improving balance in people with PD. Meta-analysis was performed using random effects models and reported as mean difference and 95% confidence intervals. Risk of bias was assessed using Cochrane's ROB-2 tool.

RESULTS: Seventeen RCTs were eligible (n=333), utilising a range of stimulation sites, parameters, reporting tools for balance outcomes, and control/comparator groups, making the identification of clear trends and recommendations difficult. Eleven studies were deemed as having some risk of bias, four having low risk of bias and two having high risk of bias. One small meta-analysis was conducted and found no significant difference in balance outcomes. Most studies reported no significant improvement in Timed Up-and-Go scores, Berg Balance Scale scores, frequency of falls, and balance-related items of the Movement Disorder Society's Unified Parkinson's Disease Rating Scales. Some studies reported improvements in the Tinetti balance test, posturography readings, and reduction in falls though these were not supported by other studies due to a lack of reporting on these items or conflicting findings.

CONCLUSION: Current research suggests that DBS results in no significant improvement in balance dysfunction for people with PD, though such assertions require larger RCTs with clear reporting methods using validated reporting tools.