The female urethral closure mechanism during physical stress.

The closure of the urethra under the condition of stress is the result of a reflex contraction of the urethral rhabdosphincter and pelvic floor muscles. This is likely induced by activity of the abdominal muscles due to a sudden increase in abdominal pressure. This reflex contraction with an increase of urethral pressure occurs a few milliseconds before an increase in intraabdominal pressure. The urethral pressure increase during stress is only possible with fixation of the urethra by the pubourethral ligaments (PUL), facilitating urethral kinking. The highest and most important increase in pressure and resistance occurs in the distal urethra due to this kinking of the urethra.

Evolving types of pudendal neuromodulation for lower urinary tract dysfunction.

Introduction: Sacral neuromodulation and posterior tibial nerve stimulation for lower urinary tract dysfunction (LUTD) and overactive bladder yield good and reliable results. However, neuromodulation research is continuously evolving because there is still need for more patient-friendly treatment options in the therapeutic management of LUTD. Pudendal neuromodulation (PNM) has been emerging as a promising alternative treatment option for the last few decades. The aim of this study is to review the current state of the art of PNM. Material and methods: A wide literature search was conducted in the field of PNM using Medline through the PubMed database and Elsevier using the Scopus database; a critical review of the results was then carried out. PNM has been studied in its various possible aspects: percutaneous PNM, transrectal/transvaginal PNM, and both percutaneous and transcutaneous dorsal genital nerve stimulation. Results: Each technique was found to result in promising improvements in different clinical outcomes, with some trials reporting even better results than sacral neuromodulation. Conclusions: As a result of a comparison between the various PNM techniques with both sacral neuromodulation and posterior tibial nerve stimulation, we think that PNM should be seen as seriously promising, and we believe it will expand the treatment options for overactive bladder. Even though several studies accordingly showed PNM to be safe and effective, a systematic review and meta-analysis were not feasible. PNM in its various techniques is a promising treatment for LUTD. Nevertheless, further research is needed to include it in treatment algorithms.

Reconstruction of bladder function and prevention of renal deterioration by means of end-to-side neurorrhaphy in rats with neurogenic bladder.

AIMS: To investigate the feasibility of restoring bladder function and prevention of renal deterioration by neurorrhaphy in rats with neurogenic bladder (NB). METHODS: Forty-two rats were assigned to the end-to-side nerve coaptation group (ECG, n = 16), no nerve coaptation group (NCG, n = 16), and control group (CG, n = 10). In the ECG, the left ventral root (VR) and dorsal root (DR) of L6 and S1 were transected, and the distal stump of L6VR was sutured to the lateral face of L4VR. In the NCG, the left VR and DR of L6 and S1 were transected, but coaptation was not performed. In the CG, no operation was performed. Nerve regeneration, bladder function, and renal function were evaluated by FluoroGold (FG) retrograde tract tracing, cystometry, electrical stimulation, MRI, histology and biochemical assays. RESULTS: In the ECG, FG-labeled neurons were observed in the left ventral horn of L4 spinal cord. There was a significant increase in intravesical pressure upon stimulation of the left L4VR proximal to the coaptation. Maximum cystometric capacity, post-void residual urine, bladder compliance and weight, serum creatinine, blood urea nitrogen, and fibrotic area of bladder and kidney were lower in the ECG than in the NCG, but higher than the CG. Hydronephrosis was noticed in ECG and NCG rats. Maximum detrusor voiding pressure was higher in the ECG and CG than in the NCG. CONCLUSIONS: End-to-side neurorrhaphy is a useful method for restoring bladder function and preventing renal injury in rats with NB.

Effectiveness of percutaneous tibial nerve stimulation in the treatment of overactive bladder syndrome.

Overactive bladder syndrome (OAB) is a common condition affecting adults and children worldwide, resulting in a substantial economic and psychological burden. Percutaneous tibial nerve stimulation (PTNS) is derived from acupuncture used in Chinese traditional medicine and was first described in the early 1980s. It is a neuromodulation technique used to modulate bladder function and facilitate storage. Being a minimally invasive, easily applicable, but time-consuming treatment, future developments with implantable devices might be the solution for the logistical problems and economic burden associated with PTNS on the long term. This nonsystematic review provides a current overview on PTNS and its effectiveness in the treatment of OAB for both adults and children.

Clinical utility of neurostimulation devices in the treatment of overactive bladder: current perspectives.

OBJECTIVES: This review describes the evidence from established and experimental therapies that use electrical nerve stimulation to treat lower urinary tract dysfunction. METHODS: Clinical studies on established treatments such as percutaneous posterior tibial nerve stimulation (P-PTNS), transcutaneous electrical nerve stimulation (TENS), sacral nerve stimulation (SNS) and sacral anterior root stimulation (SARS) are evaluated. In addition, clinical evidence from experimental therapies such as dorsal genital nerve (DGN) stimulation, pudendal nerve stimulation, magnetic nerve stimulation and ankle implants for tibial nerve stimulation are evaluated. RESULTS: SNS and P-PTNS have been investigated with high-quality studies that have shown proven efficacy for the treatment for overactive bladder (OAB). SARS has proven evidence-based efficacy in spinal cord patients and increases the quality of life. TENS seems inferior to other OAB treatments such as SNS and P-PTNS but is noninvasive and applicable for ambulant therapy. Results from studies on experimental therapies such as pudendal nerve stimulation seem promising but need larger study cohorts to prove efficacy. CONCLUSION: Neurostimulation therapies have proven efficacy for bladder dysfunction in patients who are refractory to other therapies. SIGNIFICANCE: Refinement of neurostimulation therapies is possible. The aim should be to make the treatments less invasive, more durable and more effective for the treatment of lower urinary tract dysfunction.