To evaluate, in a prospective study, the effectiveness of prostate injection of botulinum A toxin in patients who were poor surgical candidates. Patients with benign prostatic hyperplasia (BPH) are usually successfully treated with medical treatment or transurethral resection. However, some patients with chronic urinary retention or a large postvoid residual urine volume due to BPH are poor surgical candidates or are patients in whom medical treatment has failed.

Ten patients with BPH and urinary retention or a large postvoid residual urine volume received 200 U botulinum A toxin injection into the transition zone of the prostate. The clinical results and urodynamic parameters at baseline and after treatment were compared.

All patients had an improvement in spontaneous voiding after treatment. Of them, 8 had an excellent result (80%) and 2 had an improved result. Both voiding pressure and postvoid residual volume were significantly decreased after treatment. The total prostate volume was significantly reduced, and the maximal flow rate was significantly increased after treatment. The maximal effects of botulinum A toxin appeared at about 1 week and were maintained at 3 and 6 months after treatment. At 6 to 12 months (mean 9) of follow-up, no patient had had recurrence of urinary retention and the voiding condition in all patients remained at the post-treatment status. No adverse effect was noted.

Prostate injection of botulinum A toxin is an effective alternative treatment with minimal adverse effects for patients with benign prostatic obstruction who are poor surgical candidates or in whom medical treatment has failed.