- OBJECTIVE: Erectile dysfunction (ED) following radical prostatectomy is of major concern for both patients and caring physicians. We evaluated the bulbocavernosus reflex latency (BCRL) and amplitude (BCRA) following bilateral nerve-sparing radical retropubic prostatectomy (NS-RRP) to predict the response to sildenafil citrate (SC). METHODS: Patients were recruited in our ED clinic following NS-RRP. Exclusion criteria included preoperative significant ED, neurological disease, and nitrates treatment. Patients were defined as non-responders only after four consecutive unsuccessful trials of 100 mg SC. RESULTS: Twenty patients at least 3 months after surgery were included in this study. Five patients (25%) regained spontaneous erections, although insufficient for vaginal penetration. All of them had normal BCRL and normal BCRA as well as good response to 100 mg SC. Three patients (15%) lacked spontaneous erections and had prolonged BCRL with normal BCRA. This subgroup eventually regained erections using SC. Twelve patients (60%) lacked spontaneous erections and had prolonged BCRL and low BCRA. They failed SC trials and achieved erections using intra-cavernosal injections (ICI) of 10 microg PGE(1). CONCLUSIONS: Neurophysiologic evaluation consisting of BCRL and BCRA was found to be useful in the prediction of the response to SC following bilateral NS-RRP. Patients who do not regain an erection, and have abnormal BCRL and BCRA 6 months after surgery, will probably be SC non-responders and may benefit from ICI. A subset of patients with preserved BCRA and prolonged latencies has been shown to have a better chance to respond to SC.