Detrusor underactivity (DU) or underactive bladder (UAB) is a common urological condition that has been receiving specific interest recently. We report the long-term outcomes of sacral neuromodulation (SNM) in detrusor underactivity (DU) and chronic non-obstructive urinary retention.

This multicentric retrospective case series study was conducted between March 2017- October 2020 in two referral functional urology centers in Iran and Turkey. Local ethics permission was gained. Patients who suffered from DU or chronic non-obstructive urinary retention, refractory to conservative therapies (life style modifications, pharmacological treatment) were enrolled in this investigation. A total of forty-six cases underwent SNM between March 2017 and October 2020. To assess patients’ response to treatment (stage I), temporary percutaneous stimulation was used prior to permanent implantation. Patients were observed for two weeks following surgery, and if treatment response was 50 percent or more, the implantable pulse was placed in stage II of the study.

The mean age of patients was 37.46 ± 13.58 years, with a male to female ratio of 1:1. The etiology of disease in 32 patients (69.6%) was idiopathic, while the others had neurogenic conditions.   Thirty-two (69.6 %) patients responded to stage I, of which 75%  either experienced a reduction in CIC frequency, PVR, or void spontaneously , or were fully treated by the end of stage II. Fourteen patients (7 idiopathic, 7 neurologic) showed no response to stage I . The mean follow-up interval was 18.16 (2-46) months. Voided volume improved significantly, from a median of 62.50 (range 0.0-600.0) to 226.50 (range 0.0-550.0) (p < 0.001). The median PVR was reduced from 400 (range 150.0 to 1000.0) to 170 ml (range 0 to 800) (p < 0.001), and the median Qmax from 2 (range 0 to 13) to 12 (range 0 to 21) (p < 0.001). Idiopathic DU cases showed statistically significant improvement in their urodynamic study results for voided volume (P=0.004), Qmax (P=0.023), and PVR (P=0.040) as compared to neurogenic patients.In addition, the GRA(Global Response Rate) of idiopathic cases showed better success than neurogenic patients (P= 0.008). Although no complications occurred during stage I,  two device revisions (due to pain at implantation site), three cases of lead migration, one implantation site infection, and One case of pain and spasm in the lower extremity without lead migration were observed during the follow-up period of stage II.

This retrospective multicenter study has advanced the overall knowledge of SNM therapy for underactive bladder. The results showed that SNM effectively and safely provides promising results for refractory cases of DU, in whom the first and second line treatment have failed.

SNM effectively and safely provides promising results for refractory cases of DU, in whom the first and second line treatment have failed.