Neuromodulation by implant for treating lower urinary tract symptoms and dysfunction

Objective: Patients with irritative micturition complaints, pelvic pain, involuntary urine loss or urinary retention are sometimes difficult to treat, The advent of direct sacral nerve stimulation offers a therapeutic alternative if conservative measures fail and surgery is considered. This paper reviews therapeutic neuromodulation by implant for treating lower urinary tract symptoms and dysfunction. Methods: The international literature is reviewed on topics such as the physiological basis of neuromodulation, techniques of acute testing and chronic implantation, and clinical results. Future developments and ways for possible improvement are discussed. Results: The mode of action of neuromodulation is probably through restoring the correct balance between excitatory and inhibitory impulses from and to the pelvic organs at a sacral and supra-sacral level. Depending on the predefined success criteria, average success rates of definitive implants vary from 50 to 70%. From the data it seems that patients with urge incontinence and urinary retention are the best candidates for neuromodulation. In the literature the lack of standardisation of selection criteria, stimulation parameters and definitions of success is striking. Conclusions: Neuromodulation by implant is a useful therapeutic alternative. It should at least be considered in patients with therapy-resistant urge incontinence and urinary retention before proceeding to surgery. Issues such as underlying physiology, methodological standardisation, technical improvements, and patient selection must be addressed in future research.