The aim of this study is to evaluate the effectiveness of sacral neuromodulation (SNM) on clinical symptoms, lower urinary tract function, and objective measurements in patients diagnosed with overactive bladder (OAB) and chronic nonobstructive urinary retention (CNOUR), and to identify factors affecting treatment response.

This retrospective study included patients diagnosed with OAB and CNOUR who underwent SNM. All patients underwent a standard two-stage SNM protocol. In the first stage, permanent implantation was performed in patients who experienced ≥50% symptom improvement after test stimulation. Clinical evaluation was performed using urinary incontinence status, clean intermittent catheterization (CIC) requirement, bladder diary data, and uroflowmetric parameters. Demographic and technical factors affecting success were analyzed.

A total of 160 patients were included in the study. 70.6% of the patients were female, and the mean age was 41 years. 39.4% of the patients were diagnosed with OAB, and 60.6% with CNOUR. After the first stage of SNM, clinical success was achieved in 79.4% of the OAB group and 70.1% of the CNOUR group. In the CNOUR group, the need for CIC completely disappeared in 38.2% of patients after SNM, while the frequency of catheterization decreased by at least 50% in 22.1% of patients. Urinary incontinence completely resolved in 52% of the OAB group and 69.1% of the CNOUR group. In uroflowmetric evaluation, a significant increase in voiding volume was observed in the OAB group, while no significant changes were detected in maximum flow rate and residual volume. In the CNOUR group, the maximum flow rate increased significantly and a marked decrease in postvoid residual volume was observed. Bladder diary data showed a decrease in daytime voiding frequency and an increase in the mean daytime voided volume in the OAB group. Age, gender, smoking and alcohol use, history of surgery, and side of SNM application did not have a significant effect on success. A high number of contacts receiving stimulation in the first phase was found to be significantly associated with success. No serious perioperative complications were observed.

This study thoroughly evaluated the effects of SNM on clinical symptoms, voiding functions, and objective measurements in patients diagnosed with OAB and CNOUR. Our study contributes significantly to the SNM literature due to its large patient sample size and inclusion of both storage and voiding phase disorders. The findings demonstrate that SNM is a viable treatment option for both patient groups but also suggest that the clinical response to neuromodulation may vary depending on the indication.

Sacral neuromodulation is an effective and safe treatment option for patients with overactive bladder and chronic urinary retention. Its ability to reduce the need for catheterization and improve voiding function is of great clinical importance, especially in patients with chronic urinary retention. The success of SNM can be increased with appropriate patient selection, careful evaluation during the testing phase, and optimal technical application.