Clinical effect of alpha-1 antagonism by terazosin on external and internal urinary sphincter function

The purpose of this investigation was to determine the effectiveness of alpha-1 blockade in the treatment of bladder outlet obstruction in the spinal cord injured (SCI) patient. We evaluated terazosin, a selective alpha-1 blocker, in 15 normotensive SCI patients. Detrusor-external sphincter dyssynergia (DESD), without obstruction of the bladder neck or prostate, was documented in all patients using video-urodynamic evaluation. Urodynamic testing was performed both before and during treatment with terazosin (5 mg nightly). Voiding pressure before and during terazosin therapy averaged 92 +/- 17 and 88 +/- 27 cm H2O, respectively (p = 0.48). After subsequent external sphincterotomy or sphincter stent placement, the voiding pressure was reduced to 38 +/- 15 cm H2O (p < 0.001). Nine other patients suffered from persistent difficulty voiding after previous sphincterotomy. Each was subsequently treated with oral terazosin. In five patients who improved with this treatment, urodynamic parameters demonstrated obstruction only at the bladder neck, with no evidence of obstruction at the level of the external sphincter. The four patients who failed to improve were documented to have an open bladder neck but obstruction at the level of the external sphincter. Our data show that alpha-1 sympathetic blockade has no effect on external sphincter function and does not significantly relieve functional obstruction caused by DESD. It was also noted that terazosin is helpful in diagnosing and treating internal sphincter (bladder neck and prostate) obstruction especially in patients who have persistent difficulty voiding after external sphincterotomy.