**5. Conclusions**

BoNT-A urethral sphincter injection is effective in approximately 60% of patients with voiding dysfunction due to NVD or NNVD, refractory to conventional medical treatment. Careful VUDS interpretation of bladder neck opening and measurements of a higher detrusor or abdominal pressure enabled us to select candidates suitable for urethral sphincter BoNT-A treatment.

**Author Contributions:** Y.-K.L.: Perform urodynamics and manuscript writing. H.-C.K.: Study design, data interpretation, and critical review.

**Funding:** This research received no external funding.

**Acknowledgments:** This study was supported by the grant of Tzu Chi Medical Foundation TCMF-MP-107-02-01.

**Conflicts of Interest:** The authors declare no conflict of interest.
