Sacral nerve neurostimulation-neuromodulation in the treatment of lower urinary tract dysfunction. Basic principles-indications-clinical application-results

During the last fifteen years, sacral nerve neuromodulation-neurostimulation has begun to be developed as a therapeutic tool for the treatment of refractory chronic lower urinary tract dysfunction. This is a comprehensive review of the current state of the art of this surgical innovation in terms of basic principles, indications, clinical application, complications and results. The mode of action of neuromodulation is still not fully understood, but it is hypothesized that the electrical current modulates reflex pathways involved in the filling and evacuation phases of the micturition cycle, rebalancing micturition control. The main indication for intervention is chronic voiding dysfunction, refractory to conventional treatments, causing urgency-frequency syndrome, urge incontinence and idiopathic (non-neurogenic) voiding difficulty. Less common indications are multiple sclerosis, suprasacral spinal cord injuries, stroke, and Parkinson's disease. Its clinical application consists principally of three stages: Percutaneous location of the sacral spinal nerve with a needle electrode, percutaneous test stimulation with wire electrodes to assess the therapeutic potential in the individual patient over a period of 4 to 14 days, and permanent implantation of the neurostimulation device. Complications are usually minimal (rate 22-43%) and can be classified into surgery-related morbidity, neurophysiological alterations and hardware problems. The mean total clinical success rate has been estimated to be 88%, 80% and 71% in cases of urgency-frequency, urge incontinence and idiopathic urinary retention, respectively. On the basis of these results, it appears that sacral nerve neuromodulation represents an effective alternative treatment modality in patients with various forms of chronic lower urinary tract dysfunction refractory to conventional treatment, successfully bridging the gap between conservative treatment options and highly invasive surgical procedures.