Neurogenic lower urinary tract symptoms (nLUTS) occur after the abnormal function of the bladder and urethra in the setting of a neurologic disorder (1). The etiology differs between patients, and the symptoms are determined by the site and nature of the lesion. The neurogenic overactive bladder (nOAB) usually presents in severe central nervous system diseases and spinal cord lesions (2).

Sacral neuromodulation (SNM) involves the electrical stimulation of the sacral nerve to modulate the neural pathway, indicated as a third-line of treatment for overactive bladder, urinary retention secondary to detrusor underactivity, detrusor sphincter dyssynergia, and fecal incontinence (3). Nowadays, there is no recommendation for using SNM in neurogenic patients, however, different studies tend to follow the same criteria used for patients with idiopathic lower urinary tract dysfunction (LUTD). 

This study aims to determine the effectiveness and safety of sacral neuromodulation in patients with neurogenic lower urinary tract symptoms.

This study was performed under the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (The PRISMA Statement, 2020) and the Conducting Systematic Reviews and Meta-Analyses of Observational Studies of Etiology (COSMOS-E, 2021).

The literature search was performed by two researchers and coauthors including the terms: (‘Neurogenic Lower Urinary Tract Symptoms’ OR ‘Neurogenic Lower Urinary Tract Dysfunction’ AND ‘Sacral Neuromodulation’) in the databases OVID, MEDNAR, Embase, Scopus, Web of Science, and PubMed, including all studies until March 2024. 

We included 45 observational studies that evaluated adults with nLUTS, who underwent SNM phase I, phase II, or both, after the exclusion of 1062 duplicates, gray literature, case reports, studies on children, and articles written in languages other than English and Spanish.

For the analyses, we stratified the patients by neurological disease and symptoms. Success was defined as the improvement of the symptoms by the percentage considered in each study, which was at least 50% according to the ICS terminology (1). 

The success variable was evaluated as a proportion. For every study, the size effect (TE) and the TE standard error (seTE) were calculated. The meta-analysis was performed under the model of random effects. Heterogeneity was evaluated with the coefficient I2. A p-value of <0.05 was considered significant. All the analysis was performed with R 3.3.0+ (R Core Team, Vienna, Austria, 2023) and RStudio 2023.12.1+402 (RStudio Team, Boston, MA, 2020).

A total of 1221 patients with nLUTS were included from 45 studies, 625 were men, 465 women, and 131 were not specified. SNM Phase I was performed in 92 patients, Phase II in 229, and both Phases in 900. 

The meta-analysis of proportions showed a global improvement after SNM Phase I of 61% (figure 1.A). Complications occurred in 8% of cases. After SNM Phase II, the global improvement was 78% (figure 1.B). All symptomatology improved and complications happened in 26% of patients. The complete data in Table 1.

For patients with nLUTS who underwent SNM Phase I, global improvement was 61% but studies had a high heterogeneity. However, a lower heterogeneity between studies was found when evaluating patients with Parkinson’s Disease, cerebrovascular disease, pelvic surgery, and spinal cord injury, which means the results are reliable. From these latter evaluations, the success in cerebrovascular disease was not significant, so SNM should not be recommended. However, for spinal cord injury the success was significant and happened in 39% of patients, in Parkinson’s disease 50%, and in pelvic surgery 69%. 

When stratifying by symptoms, low heterogeneity was found for urgency and urinary incontinence with a success of 63%. All symptoms have a high success rate and are statistically significant, but the studies present a high heterogeneity. Complications occurred in 8% of cases without differences between studies.

After Phase II, global success was 78% with a low heterogeneity and a high reliability. Also, a low heterogeneity was found when evaluating patients with multiple sclerosis, Parkinson’s disease, spina bifida, cerebrovascular disease, pelvic surgery, spinal disc disease, spinal cord injury and other causes. From this analysis, data was not statistically significant in Parkinson’s disease, spina bifida, cerebrovascular disease, cerebral palsy, and spinal disc disease, so SNM is not recommended. In contrast, a p <0.05 was found in multiple sclerosis with a success rate of 84%, as spinal cord injury and other causes, and pelvic surgery with 82%.

All studies present a low heterogeneity when evaluating the patients by symptomatology, and all were statistically significant with success of 89% in urgency/frequency syndrome, 85% in urgency and urinary incontinence, 83% in urinary retention, and 69% in combined ones. Complications happened in 26% of cases but had a high heterogeneity between articles.

Sacral neuromodulation Phase I and II is a safe procedure for patients with neurogenic lower urinary tract symptoms, and is effective in multiple sclerosis, spinal cord injury, pelvic surgery, and other causes different than Parkinson’s disease, spina bifida, cerebrovascular disease, cerebral palsy, and spinal disc disease.

Gajewski JB, Schurch B, Hamid R, Averbeck M, Sakakibara R, Agrò EF, et al. An International Continence Society (ICS) report on the terminology for adult neurogenic lower urinary tract dysfunction (ANLUTD). Neurourol Urodyn. 2018 Mar;37(3):1152–61.
DeWitt-Foy ME, Elliott SP. Neurogenic Bladder:: Assessment and Operative Management. Urol Clin North Am. 2022 Aug;49(3):519–32.
Goldman HB, Lloyd JC, Noblett KL, Carey MP, Castaño Botero JC, Gajewski JB, et al. International Continence Society best practice statement for use of sacral neuromodulation. Neurourol Urodyn. 2018 Jun;37(5):1823–48.