Hypothesis / aims of study
Prostatic surgery represents the principal cause of Stress Urinary Incontinence in males, seriously impairing patients’ Quality of Life (QoL). Robot Assisted Radical Prostatectomy (RARP) has lessened the incidence of this bothersome symptom, but its close identification lacks a reliable test. We recently proposed Uroflow Stop Test (UST) with surface Electromyography (EMG) to evaluate the time required to completely stop urine flow since the Pelvic Floor Muscles (PFMs) contraction occurred (1). Here, we have introduced two new parameters, the Neurological Latency Time (NLT) and the Urologic Latency Time (ULT), split by the beginning of EMG contraction recording. In this way the time necessary to contract PFMs after the stop command could be univocally interpreted, allowing to standardize the condition. The aim of this study was to investigate if a ULT <3 seconds at one month could be associated with early recovery of urinary continence after a full nerve-sparing RARP.
Study design, materials and methods
We conduct a prospective study in patients with localized Prostate Cancer who underwent RARP according to previously described PERUSIA technique (Posterior, Extraperitoneal, Robotic, Under Santorini, Anterograde) (2). One skilled surgeon performed all surgical procedures in a High Volume tertiary Institute from January 2017 to January 2018. We administered International Prostatic Symptoms Score (IPSS) and QoL questionnaires pre- and postoperatively. After careful instruction to test execution, all patients had UST–EMG pre- and postoperatively (at 1, 3, 6 and 12 months). Pad-test and direct interviews (EPIC question 5) were used at 3, 6 and 12 months to assess continence status. All patients performed PFMs rehabilitation within the first three months. At UST-EMG we studied: the NLT, from the stop command to the PFMs contraction onset and the ULT from the latter to the complete urine flow interruption. We performed statistical analysis with SPSS® software, setting as significant a p-value of 0.05.
Sixty patients were enrolled. At 1 month we identified two groups: Group 1 with ULT ≤3 seconds (17 patients) and Group 2 with ULT >3 seconds (43 patients). Preoperative characteristics, NLT, ULT, IPSS and QoL scores were comparable between the two groups. The table shows our results. At 12 months significant intragroup differences were noted in IPSS score (p <0.0001) and QoL score (p <0.04) before and after surgery both in the Group 1 and in the Group 2. Mean NLT did not differ between the two groups either pre-RARP and at 12 months. NLT underwent a significant reduction between pre- and postsurgery (at 12 months) in both groups (p <0.02 in Group 1 and p <0.01 in Group 2). Surgical damages seems to determine a significant augmentation of ULT from pre-operative data to 12 months data in both groups (p =0.00003 in Group 1 and p =0.00001 in Group 2). An intergroup statistical significance is also present at 12 months after RARP (p <0.05). Regarding continent patients, a difference was present at 6 months after surgery (p <0.05), but it was not more present at 12 months (p =0.518). In the Group 2 we demonstrated a significant difference between 3 and 12 months (p =0.028) in terms of continence rate.
Interpretation of results
If we think urinary continence to be the result of co-partnership of several pelvic muscles, the anatomic integrity of vascular and nervous supply helps their contractile activity. Our PERUSIA technique, characterized by a medial, intrafascial, anterograde, Santorini-sparing approach, reduces the injury of pudendal nerve branches to the rhabdosphincter that is close to the prostate apex and endopelvic fascia. An ealy identification of Urinary Incontinence after RARP is mandatory to establish the best rehabilitation program. The ULT decreased after the first month from surgery mainly because of nervous recovery from neuropraxia, while NLT may decrease because of patients’ storing information during PFMs application. A ULT<3 seconds at 1 month seems to be associated with earlier urinary continence achievement, with a better mid and long-term outcome too. Moreover the ULT calculation can give us an estimate of the efficiency of the muscular continence apparatus during PFMs. The small sample represents the main limitation of our study and it may have limited our statistical power.