It would be worth reading articles by Dr Walsh and Dr Scardino on nerve sparing and nerve grafting.
Johns Hopkins have information in some of their newsletters available at www.urology.jhu.edu/newsletter.
Both doctors have published books on prostate cancer: "Dr Peter Scardino's Prostate Book" covers surgery, nerve sparing and nerve grafting in detail. He indicates that when one nerve is removed and replaced by a graft, the result is about as good as when both nerves are spared, and more than twice as good as the outcome without grafts.
John