Sacral Neuromodulation for Refractory Overactive Bladder: Closing the Gaps in Anatomy, Mechanisms, and Parameter Selection

Sacral neuromodulation is an effective therapy to control overactive bladder symptoms, yet the underlying mechanisms and optimal stimulation parameters remain unclear. Analysis of 45 clinical studies from 1994 to 2023 demonstrated no significant change in rates of long-term symptom control despite technological advancements, and analysis of recent studies (2015 onward) showed that more than 40% of patients receiving test stimulation do not benefit from sacral neuromodulation. Critical knowledge gaps persist. A lack of evidence guiding stimulation parameter selection has resulted in largely unchanged programming protocols since initial US Food and Drug Administration (FDA) approval in 1997. There is little knowledge of sacral nerve anatomy or nerve fiber organization, and the specific neural pathways mediating therapeutic effects remain unclear. Additionally, there is a limited understanding of how anatomical variations affect stimulation outcomes and few validated predictors of long-term success. We propose that developing detailed computational models incorporating realistic nerve morphology and tissue properties, combined with systematic documentation of programming parameters and outcomes will enable development of more effective stimulation protocols and electrode designs. Bridging these knowledge gaps is essential for improving the consistency and efficacy of sacral neuromodulation for refractory overactive bladder.