Urologic latency time during uroflow stop test with electromyography: an incontinence detector in rehabilitation after robotic radical prostatectomy

BACKGROUND: Stress urinary incontinence (UI) is the most common presentation following robot-assisted radical prostatectomy (RARP), but a postoperative non-invasive and objective test is still lacking. To assess pelvic floor integrity after RARP, we recently proposed Uroflow Stop Test (UST) with surface electromyography (EMG). AIM: Here we provide two new clinical parameters: the neurologic latency time (NLT) and the urologic latency time (ULT) derived from UST-EMG Test. Principal outcome was to evaluate their variation during one year follow-up and ULT ability to predict post-RARP UI. DESIGN: Observational and longitudinal study. SETTING: Interdivisional Urology Clinic (Perugia-Terni, Italy). POPULATION: Patients with prostate cancer treated with a full nerve-sparing RARP who underwent postoperative pelvic floor muscles training (PFMT): a diurnal functional home program and a weekly hospital program with the use of biofeedback, between 1 and 3 months postoperatively. METHODS: All patients consecutively performed a UST-EMG test at one, three, six, and twelve months after surgery. At each follow-up visit we collected NLT values, ULT values, 5-item 26-Expanded Prostate Cancer Index (EPIC), Incontinence Developed on Incontinence Questionnaire (ICIQ-UI) Short Form and International Prostate Symptom Score (IPSS). We analysed statistically significant differences in NLT and ULT between continent and incontinent patients and we evaluate the diagnostic ability of 1-month post-surgery ULT value to diagnose the presence of postoperative UI. RESULTS: Sixty patients were enrolled. The mean time to PFMT was 31.08 (range: 30-35) days. Overall IPSS, NLT and ULT had similar trends: progressive decrease until the six months after surgery (1-month vs. 3 months vs. 6 months, P<0.05) to plateau thereafter. When considering the two group of patients, IPSS and NLT were significantly higher in the incontinent group only one month after surgery, while ULT became similar between the two groups at 6 months after surgery. The best cut-off of 1-month ULT values that maximized the Youden function at 12-months resulted 3.13 second. CONCLUSIONS: NLT and ULT may respectively account for the nerve and the urethral closure system integrity post-RARP. In the first month after RARP, both NLT and ULT differs between incontinent vs. continent patients. NLT become similar between two group after one month, confirming the recovery from neuropraxia, but ULT remains statistically significant different until 3 months postoperatively. The value of 1-month ULT resulted a valid tool to predict incontinence status at 12 months. CLINICAL REHABILITATION IMPACT: ULT and NLT may be also useful tools to monitor the continence progressive recovery after RARP and they may help rehabilitation specialists to evaluate the ongoing results during postoperative follow-up.