Efficacy of bilateral sacral neuromodulation in treating neurogenic bladder and bowel dysfunction

Neurogenic bladder-bowel dysfunction remains refractory to conventional therapies in many patients. While unilateral sacral neuromodulation (SNM) is established, comparative evidence for bilateral stimulation in combined dysfunction is lacking. This study evaluated whether bilateral SNM outperforms unilateral stimulation in this population.

In this two-center retrospective study, 20 patients with neurogenic bladder and bowel dysfunction underwent a self-paired sequential testing protocol comparing pre-operative baseline, unilateral stimulation, and bilateral stimulation stages. Outcomes included voiding diary parameters, uroflowmetry, Neurogenic Bowel Dysfunction (NBD) score, and Wexner scores. Long-term follow-up was conducted at 1 and 2 years for patients receiving permanent bilateral implantation (n=12).

Bilateral stimulation significantly outperformed unilateral stimulation in 6 of 8 parameters (all P<0.05). Voided volume increased from 109.0±38.6 to 165.5±39.3 mL, while post-void residual decreased from 254.5±113.9 to 177.5±79.3 mL. Maximum flow rate improved from 7.5±2.0 to 12.0±2.4 mL/s. Bowel function also improved significantly: NBD score decreased by 33.3%, Wexner constipation score by 21.4%, and Wexner incontinence score by 40.0%. However, no significant additional benefit was observed for 24-hour voiding frequency or urgency/UUI episodes when comparing bilateral to unilateral stimulation. Among 12 patients with permanent implants, therapeutic improvements were sustained at 2-year follow-up, with further significant gains in voided volume, post-void residual, and bowel function compared to Year 1.

Bilateral SNM provides superior and sustained improvements in both voiding and defecatory functions compared with unilateral stimulation, offering an effective treatment for refractory neurogenic bladder-bowel dysfunction.