Papaverine testing of impotent patients following nerve-sparing radical prostatectomy.

To investigate the etiology of impotence following nerve-sparing radical retropubic prostatectomy we performed papaverine testing on 23 patients who did not regain erections sufficient for vaginal penetration. Intervals from surgery to testing ranged from 3 to 30 months, with an average of 9 months. All patients achieved some degree of tumescence. In response to intracavernous papaverine injection only 1 patient (5 per cent) obtained an erection equivalent to the preoperative state. Of 18 patients who were fully potent preoperatively 8 (44 per cent) achieved an erection less than normal but judged to be sufficient for intercourse by the examining physician. Twelve patients, including 2 who were not fully potent preoperatively, had erections of poor quality insufficient for vaginal penetration. The results suggest that in most of these patients postoperative erectile dysfunction is predominantly vasculogenic in origin. Thus, factors other than injury to the neurovascular bundles may be responsible for postoperative impotence.