Initially the first publication by EA Tanagho reported about an initial 22 neurogenic patients treated successfully with Sacral Neuromodulaton. For more than 20 years SNM has been used in carefully selected patients with nLUTD (neurogenic detrusor overactivity, chronic, non-obstructive urinary retention or a combination of both)[1,2]. This systematic literature review and meta-analysis aims to re-evaluate the effectiveness and safety of SNM in patients with nLUTD, since recently introduced MRI compatible devices may offer more treatment options in clinical practice[3].

A systematic literature research was performed based on Embase (OvidSP); MEDLINE (OvidSP); MEDLINE In-Process Citations & Daily Update (OvidSP); MEDLINE (OvidSP) e-Pub ahead of print; Cochrane Central Register of Controlled Trials (CENTRAL); NIH Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) between 1998 and March 2020, supplemented by a hand search. The systematic literature review was conducted according to the PRISMA statement, including PICOS and risk of bias.

47 studies were identified. 21 studies comprising a total of 887 patients were included in the meta-analysis of test SNM. The pooled success rate of SNM test stimulation was 66.2% (95% CI 56.9–74.4). Test success rates for back surgery and multiple sclerosis were significantly higher than those for incomplete SCI (84.1% and 76.6% versus 48.3%). No treatment success has been reported in patients with complete spinal cord injury unless SNM is applied in the spinal shock phase. Dividing nLUTD in the three subgroups (neurogenic detrusor overactivity, neurogenic non-obstructive chronic urinary retention, or a combination of both) revealed test success rates of 61%, 52%, and 69%, respectively. A total of 428 patients from 24 studies were included in the meta-analysis of permanent SNM. The success rate of pooled permanent SNM was 84.2% (95% CI 77.8–89.0). Among the identified studies, the most common adverse events (AEs) were loss of effectiveness, infection, pain at implant site and lead migration with AE rates of 4.7%, 3.6%, 3.2% and 3.2%, respectively. Significant study limitations have been identified such as low level of evidence (Oxford classification: 3-4) of included studies, significant risk of bias, in part small sample sizes, substantial between-study heterogeneity and heterogeneous patient populations. Long-term data up to 5 years have been reported.

Success rates of permanent SNM as well as the frequency of adverse events were similar to idiopathic patients. Test success rates varied greatly depending on the type of neurologic condition. The highest test success rates were achieved in patients with back surgery and multiple sclerosis. Complete spinal cord injury is commonly considered as a general contraindication for SNM unless patients are treated in the spinal shock phase.

Although patients with nLUTD were the first treated successfully at the early days of SNM, it was not a realistic option in routine clinical practice, because full-body MRI approved devices were lacking in the past. Since this meta-analysis supports the treatment benefits of permanent SNM for various nLUTDs, the therapeutic armamentarium for this challenging, very heterogeneous patient group can be complemented. Overall SNM success rates were similar to idiopathic patients. Moreover, our data showed that SNM is safe for nLUTD patients. The results from this large meta-analysis can be interpreted as real-world data providing significant real-world evidence for such a heterogeneous group of patients. However, more vigorous studies for various subpopulations are needed before definitive conclusions can be drawn.

Kessler TM, La Framboise D, Trelle S, Fowler CJ, Kiss G, Pannek J, Schurch B, Sievert KD, Engeler DS. Sacral neuromodulation for neurogenic lower urinary tract dysfunction: systematic review and meta-analysis. Eur Urol. 2010 Dec;58(6):865-74.
Averbeck MA, Moreno-Palacios J, Aparicio A. Is there a role for sacral neuromodulation in patients with neurogenic lower urinary tract dysfunction? Int Braz J Urol. 2020 Nov-Dec;46(6):891-901.
van Ophoven A, Engelberg S, Lilley H, Sievert KD. Systematic Literature Review and Meta-Analysis of Sacral Neuromodulation (SNM) in Patients with Neurogenic Lower Urinary Tract Dysfunction (nLUTD): Over 20 Years' Experience and Future Directions. Adv Ther. 2021 Apr;38(4):1987-2006.