Vaginal Lubrication and Pressure Increase Induced by Pudendal Nerve Stimulation in Cats

Abstract

ABSTRACT Background Vaginal lubrication and contractions are among the top difficulties affecting sexual intercourse in women after spinal cord injury. Aim This study aimed at determining if pudendal nerve stimulation (PNS) can improve vaginal lubrication and induce increases in vaginal pressure. Methods In anesthetized cats, a small piece of cotton was inserted into the vagina for 10 minutes with or without PNS to measure vaginal wetness by the weight increase of the vaginal cotton. Then, a small balloon catheter was inserted into the vagina to measure the pressure increase induced by PNS. Intensity response of the vagina to PNS (30 Hz, 0.2 ms, 5 seconds) was determined at 1–4 times of intensity threshold (T) for PNS to induce an observable vaginal pressure increase. Frequency response was determined at 2T intensity in a range of PNS frequencies (5–50 Hz). Finally, fatigue in vaginal pressure was determined by applying PNS (30 Hz, 2T) either continuously or intermittently (5 seconds on and 5 seconds off) for 4 minutes. Outcomes The effectiveness of PNS in increasing vaginal wetness and pressure is evaluated. Results PNS significantly (P = .0327) increased the measurement of vaginal wetness from 15.8 ± 3.8 mg during control without stimulation to 32.4 ± 4.7 mg after stimulation. Vaginal pressure increased as PNS intensity or frequency increased. PNS (30 Hz, 2T) induced vaginal pressure increase ≥80% of the maximal response. Intermittent PNS induced significantly (P = .0354) smaller fatigue (45.6 ± 3.7%) in vaginal pressure than continuous PNS (69.1 ± 3.0%) during the 4-minute stimulation. Clinical Translation This study raises the possibility of developing a novel pudendal neuromodulation device to improve female sexual function after spinal cord injury. Strengths & Limitations This study provides preclinical data supporting the development of a novel pudendal neuromodulation device. The limitation includes the lack of chemical analysis of the vaginal secretion. Conclusion PNS can improve vaginal lubrication and induce increases in vaginal pressure.