Sacral nerve stimulation (SNS) is a well-established treatment option for various bladder dysfunctions, including overactive bladder (OAB) and underactive bladder (UAB). While numerous studies have investigated the efficacy of SNS in treating OAB, there is limited knowledge regarding factors associated with SNS success in patients with UAB.
This retrospective study aimed to evaluate the urodynamic profile of patients with UAB who received SNS and determine the proportion of patients who underwent second stage SNS and those who had SNS removal.

We conducted a comprehensive chart review of every patient who underwent SNS at the University of Miami over the past 5 years. A sub-analysis was performed on 20 patients with a diagnosis of UAB out of a total of 72 patients. Urodynamic study data, including maximum detrusor pressure (Pdet max), detrusor pressure at maximum flow rate (Pdet at Qmax), maximum flow rate (Qmax), post-void residual (PVR), end filling detrusor pressure (End Filling Pdet), and catheter use were collected. The main outcomes were the proportion of patients who underwent second stage SNS and those who had SNS removal.

Among the 20 UAB patients who underwent SNS, 18 (90%) were female and 2 (10%) were male. The mean age of the cohort who progressed to second stage SNS was 50 years (SD 9.6) and the mean age of the cohort who did not progress was also 50 years (SD 14.3). Of the patients who progressed to second stage SNS, the average Pdet max was 39.29 cm H2O (SD 23.3), the average Pdet at Qmax was 29.8 cm H2O (SD 19.5), the average Qmax was 7.49 mL/s (SD 5.5), and the proportion of patients using clean intermittent catheterization (CIC) was 40%. In comparison, the cohort who did not progress had an average Pdet max of 27.00 cm H2O (SD 17.4), an average Pdet at Qmax of 10.86 cm H2O (SD 6.2), an average Qmax of 13.54 mL/s (SD 10.5), and a proportion of patients using CIC of 50%.

This study suggests that SNS can be an effective treatment option for patients with UAB. Patients who progress to second stage SNS may have a different urodynamic profile compared to those who do not progress, with higher mean Pdet max, mean Pdet at Qmax, and lower Qmax. Additionally, a higher proportion of patients who did not progress required CIC. The findings of this study provide important insights into the factors that may influence the success of SNS in patients with UAB. Further research is required to confirm these findings and identify additional factors associated with SNS success.

In conclusion, this retrospective study provides valuable insights into the urodynamic profile of patients with underactive bladder (UAB) who received sacral nerve stimulation (SNS). The study found that SNS can be an effective treatment option for UAB, with a high proportion of patients progressing to second-stage SNS. Patients who progressed to second-stage SNS had a different urodynamic profile compared to those who did not progress, with higher mean Pdet max and Pdet at Qmax, and lower Qmax. These findings suggest that specific urodynamic parameters may be useful predictors of SNS success in patients with UAB. However, additional research is necessary to confirm these findings and determine other factors that may influence SNS success in UAB patients. Overall, this study provides valuable information that can guide clinical decision-making and help improve patient outcomes.