Non-invasive neuromodulation for LUTS in Parkinson's disease: a comprehensive systematic review and meta-analysis of tibial nerve stimulation with GRADE evaluation.

BACKGROUND: Lower urinary tract symptoms (LUTS) are a common and burdensome part of Parkinson's disease (PD). Conventional treatments are inconsistently effective, making minimally invasive options like tibial nerve stimulation (TNS) promising. However, evidence for TNS in PD patients remains limited and varied. PURPOSE: To evaluate the efficacy of TNS (percutaneous and transcutaneous) for LUTS in patients with PD, focusing on both subjective symptom outcomes and objective urodynamic parameters through a systematic review and meta-analysis. METHODS: A systematic search identified relevant randomized controlled trials (RCTs) and prospective single-arm studies on PTNS efficacy. Data were analyzed using RevMan Cochrane software (v5.4) and R (v4.3.2), with results pooled as mean difference (MD) or standardized mean difference (SMD) and 95% confidence intervals. Meta-regression assessed the influence of PD duration. RESULTS: Seven studies (three RCTs and four prospective cohorts) were included in this review, with a total of 591 participants. TNS improved urodynamic outcomes, including first involuntary detrusor contraction volume (+ 107.49 mL, 95% CI 99.43 to 115.56), maximum cystometric capacity (+ 90 mL, 95% CI 83.14 to 96.84), and detrusor pressures (Pdetmax and PdetQmax reductions). In contrast, pooled evidence remained heterogeneous and inconsistent for patient-reported outcomes, including urgency, frequency, incontinence, and nocturia. Meta-regression analysis revealed no significant association between PD duration and treatment response. CONCLUSIONS: TNS improved urodynamic function in PD patients, but this objective improvement does not consistently translate to subjective symptom relief, highlighting the complexity of PD-related LUTS. Future adoption requires larger, standardized RCTs with extended follow-up to identify which patients benefit most.