Efficacy of first-generation Cavermap to verify location and function of cavernous nerves during radical prostatectomy: a multi-institutional evaluation by experienced surgeons

Abstract

Objectives. To evaluate, using five experienced surgeons, the efficacy of the first-generation Cavermap Surgical Aid to identify the cavernous nerves intraoperatively and to predict the recovery of sexual function. This study was not designed to determine whether this device improves the ability to preserve the nerves or improve outcome. Methods. Fifty men younger than 60 years old (mean age 52.5 years; range 43 to 59) with clinically localized prostate cancer (76% T1c, mean Gleason score 6, prostate-specific antigen level less than 10 ng/mL) underwent nerve-sparing radical prostatectomy (90% bilateral). Intraoperatively, the Cavermap device was used to test for the presence of the cavernous nerves once the neurovascular bundle was identified visually and to determine whether the nerves were intact after the prostate was removed. Erectile function was evaluated using the International Index of Erectile Function; men were considered potent if they were able to achieve unassisted intercourse in at least one half of their attempts. Results. Before the removal of the prostate, the tumescence response to stimulation of the neurovascular bundle was 87.8%; when tissue not containing the neurovascular bundle was stimulated, no tumescence response occurred in 54%. After prostatectomy, a bilateral response to stimulation occurred in 90%, a unilateral response in 5%, and no response in 5%. Postoperatively, 71% of the patients were potent at 12 months. In the patients who demonstrated bilateral stimulation after removal of the prostate, 78% were potent at 12 months. Conclusions. After radical prostatectomy performed by experienced surgeons, patient-reported potency rates in men younger than 60 years of age were high. Cavermap stimulation demonstrated an 87.8% sensitivity and 54% specificity in locating the neurovascular bundle as identified by experienced surgeons. The lack of specificity of this first-generation device limits its application for deciding which structures can be safely preserved or excised. Because virtually all patients demonstrated a positive response after removal of the prostate, the value of stimulation to predict the recovery of sexual function is yet to be determined.