Patients will be admitted and BoNT-A (treatment group) or normal saline (control group) injections will be performed in the operation room where complete cardiovascular monitoring is available during the operation. BoNT-A injections are made under cystoscopy guide in male patients and injecting periurethrally in female patients. The BoNT-A will be purchased from Allergan Company (Botox, 100 units/vial, Irvine, California, U.S.A.). Each vial of BoNT-A will be diluted to 5 ml by normal saline. A total of 100 units of BoNT-A will be injected deeply into the external sphincter at the 3, 6, 9 and 12 o'clock positions in approximate equal aliquot. After BoNT-A injections, a 14 Fr Foley catheter will be indwelled routinely for 1 day and then removed. Patients will be followed up for their voiding conditions. When dysuria persists, intermittent catheterization will be advised instead of indwelling Foley catheter. Antibiotics will not be necessary unless urinary tract infection occurs, and medications to reduce urethral sphincteric resistance are discontinued.