Novel Concept Enabling an Old Idea: A Flexible Electrode Array to Treat Neurogenic Erectile Dysfunction

Introduction: Many studies have shown that electrostimulation of the cavernosal nerve can induce and maintain penile erection. Based on these discoveries, neurostimulation to activate the erectile response has been considered a potential solution to treat erectile dysfunction (ED). However, despite recognized potential, this technology has not been further developed. The barrier is the complex anatomy of the human cavernous nerve, which challenges the intraoperative identification of the cavernosal nerves for electrode placement. Aim: To overcome this major barrier, we proposed a practical solution: a 2-dimensional flexible electrode array that can cover the entire plexus area, ensuring that at least 1 of the electrodes will be in optimal contact with the cavernosal nerve, without the need of intraoperative identification. The present study aims to evaluate this concept intraoperatively. Methods: 24 patients enrolled for open radical prostatectomy were recruited. During the surgical procedures, the electrode array was positioned on the pelvic plexus (on the prostatic apex or pelvic wall) and electrical stimulation was applied to induce penile erection. Penile erectile response was assessed by (i) visual change of penile tumescence and (ii) by a penile plethysmograph system. Main Outcome Measure: Ability and success rate of evoking penile response were measured by applying electrical stimulation using the developed electrode array. Results: Electrical stimulation produced immediate penile response in all cases when tested before (on prostatic apex) or after prostate removal (on pelvic wall). Clear visual penile engorgement was observed in 75% of the cases, whereas 25% showed minimal to moderate penile tumescence. As expected, patients with lower International Index of Erectile Function-5 score presented a reduced response, whereas stimulation before prostate removal showed greater response than following removal. Interestingly, erectile response was potentiated by bilateral stimulation (circumference increase [mm]: 2.7 +/- 1.02 vs. 8.2 +/- 1.9, P=.01). Clinical Implications: These data bring sufficient proof of concept of a conceivable novel medical implant for the treatment of ED caused by mechanical nerve injury, such as prostatectomy and spinal cord injury. Strength & Limitations: This is the first approach that can ensure the optimal site stimulation of the erectogenic neuronal path within the lower pelvic area and overcome the major barrier of individual anatomic variability. However, because this study was performed intraoperatively in an acute scenario, further studies are needed to evaluate its chronic efficacy for clinical practice. Conclusion: The flexible electrode array concept can ensure the electrostimulation of erectogenic neuronal path when positioned on the prostate apex or pelvic floor. Copyright (C) 2018, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.