To evaluate the efficacy and safety of sacral neuromodulation (SNM) combined with botulinum toxin A (BTX-A) injection into the external urethral sphincter in the treatment of Idiopathic nonobstructive urinary retention (INOUR) with poor relaxation of the external urethral sphincter.

Data were collected from 68 patients with INOUR with poor relaxation of the external urethral sphincter who were seen in our hospital from 05/2022 to 05/2024 and who had failed to respond to conservative treatment. According to the different surgical procedure, the patients were devided into BTX group and combined group; the BTX group performed with external urethral sphincter BTX-A injection, and the combined group took sacral neuromodulation combined with external urethral sphincter BTX-A injection. All patients recorded three-day voiding diary, quality of life (QOL) score and residual urine at preoperative baseline, 1 month and 6 months postoperatively, respectively. In additional, video-urodynamics examination were also recorded at preoperative baseline and 1 month postoperatively, and the occurrence of postoperative adverse events was also recorded at 6 months postoperatively.

Compared with the baseline period, the datas of the BTX group at 1 month postoperatively showed decrease in the voiding frequency and the postvoid residual (PVR), and a significant increase in the voided volume and the maximum flow rate (MFR) (P<0.05) (Figure1). At the same time, the voiding frequency, PVR, and QOL scores of the combined group were more descreased than the preoperative baseline period; but the voided volume, MFR, BC, and MCC of the combined group were more increased than the preoperative baseline period(P<0.05) (Figure1). And the treatment effectiveness rate was 63.3% in the BTX group and 88.9% in the combined group, and the difference between the two groups was statistically significant (P<0.05) (Figure1). The datas of the combined group at 6 months postoperatively showed a significant decrease in the voiding frequency, PVR, and QOL scores, and a significant increase in the voided volume when compared to the baseline period (P < 0.05) (Figure1). Besides, five cases of vesicoureteral reflux (VUR) were seen in the BTX group preoperatively, and 2 cases improved at 1 month postoperatively，3 cases had no change. In the combined group, 6 cases of VUR were seen preoperatively, 3 cases improved and 3 cases disappeared at 1 month postoperatively. Collecting the datas of postoperative adverse events, BTX group had 8 patients developed macroscopic haematuria and 5 patients developed urinary tract infection. In the combined group, 7 patients developed macroscopic haematuria, 4 patients developed urinary tract infections, and 2 patients developed wound infections.

Compared with the baseline period, the datas of the BTX group at 1 month postoperatively showed decrease in the voiding frequency and the PVR, and a significant increase in the voided volume and the MFR, but there was no significant improvement in other indicators. The data of the combined group at 1 month postoperatively did not improve except for the maximum detrusor pressure during micturition, but all other indicators were significantly improved, and the effective rate of treatment was as high as 88.9%, which was significantly higher than that of the BTX group (63.3%).There was no difference between the 6-month postoperative follow-up data in the BTX group and the preoperative baseline data. There was no significant difference between the data of the combination group at 6 months postoperatively and the data at 1 month postoperatively, but compared with the baseline period, the above indicators were significantly improved.This suggests that combination therapy can improve short-term treatment outcomes while maintaining long-term efficacy.

Compared with BTX-A alone, BTX-A combined with SNM is more effective in improving the short-term and long-term outcomes of idiopathic non-obstructive urinary retention