Stimulation of the Neurovascular Bundle Results in Rhabdosphincter Contraction in a Proportion of Men Undergoing Radical Prostatectomy

To use nerve conduction studies to clarify the functional innervation of the male urethral rhabdosphincter. In particular, to test the hypothesis that in some men, fibres of the neurovascular bundle supply the rhabdosphincter.

These fibres may be at risk during radical prostatectomy.

Men undergoing robot assisted radical prostatectomy for clinically localized prostate cancer were included. Men with a history of pelvic surgery/radiation/trauma, obesity or neurological diseases were excluded. Nerve conduction studies were performed before and after prostate removal. The St Mark's pudendal electrode was used for pudendal (control) stimulation. The ProPep Nerve-Monitoring System™(ProPep Surgical, Austin, Tx), was used to stimulate the neurovascular bundle at the level of the prostate base, mid and apex. ProPep® needle electrodes inserted into the rhabdosphincter were used to measure evoked compound motor action potential response. Results were only included if a valid pudendal control was elicited.

Seventeen men in total underwent investigation. Valid measurements were obtained after initial quality control in seven. In two cases, evidence of sphincteric activation was observed, providing evidence to support neurovascular bundle innervation of the rhabdosphincter. In the other five patients, no intrapelvic nerve supply was demonstrated.

Somatic nerve supply to the rhabdosphincter is variable. Direct intrapelvic supply to the rhabdosphincter may exist in some men. This may be one explanation as to why some patients unexpectedly develop severe urinary incontinence post-operatively despite technically satisfactory surgery.

Urology. 2015 Oct 08 [Epub ahead of print]

Fairleigh Reeves, Wouter Everaerts, Declan G Murphy, Lynette Kiers, Justin Peters, Tim Costello, Niall M Corcoran, Anthony J Costello

Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia. Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia. , Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia; Division of Cancer Surgery, Peter MacCallum Cancer Centre, University of Melbourne, Australia. , Department of Neurology, The Royal Melbourne Hospital, Australia. , Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia. , Department of Anaesthesia, St Vincent's Hospital, Melbourne, Australia. , Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia. , Department of Urology and Surgery, University of Melbourne, The Royal Melbourne Hospital, Australia.

PubMed