Evidence of trigonal denervation and reinnervation after radical retropubic prostatectomy

Purpose: Urinary incontinence continues to be a major consequence of radica l prostatectomy. To understand the pathophysiology of this dysfunction we s tudied the impact of autonomic innervation of the superficial trigone on po stoperative urinary continence. Materials and Methods: To investigate nerve fiber density biopsies of the s uperficial trigone were obtained in 34 patients preoperatively as well as 6 weeks and 6 months postoperatively in 15 and 19, respectively. Specimens w ere Bouin fixed, paraffin embedded and processed for light microscopic immu nohistochemical evaluation using an antibody against protein gene product 9 .5, a general neuronal marker protein. In parallel we performed a comprehen sive urodynamic evaluation, including determination of maximal urethral clo sure pressure and posterior urethral sensory threshold. Results: Postoperatively protein gene product 9.5 immunoreactive nerve fibe r density was generally decreased. However, nerve fiber density after 6 wee ks of incontinence in 12 of 15 patients was only 7%, while 3 of 15 who were continent preserved 36% of initial nerve fiber density. After 6 months ner ve fiber density in 19 patients increased in 3 with incontinence to 20% and in 16 with continence to 44% of intraoperative density. Urinary incontinen ce was associated with decreased trigonal innervation, a high sensory thres hold and low maximal urethral closure pressure. Conclusions: Protein gene product 9.5 immunoreactive nerve fiber density co rresponds with posterior urethral sensory threshold and urinary continence. Thus, preserving trigonal innervation and postoperative reinnervation may be important factors for achieving early postoperative urinary continence a fter radical prostatectomy.