How does neuromodulation work

Abstract

Although sacral neuromodulation (SNM) is approved and successfully used for different urological and proctologic functional diseases for the long-term treatment, less is known about the working mechanisms underlying SNM. This review highlights SNM clinical application, the current data of LUT neuroanatomy and neurophysiology, SNM techniques and its prospective working mechanisms. Functional imaging techniques have facilitated a more detailed insight into the neural network between the central nervous system (CNS) and the lower urinary tract (LUT). In addition to the well-known factors of the spinal micturition pathway, several pontine (e.g. pontine micturition centre) and suprapontine (e.g. cingulate cortex) regions and their interactions have been identified. An attribution of CNS activity levels to different LUT conditions is possible for the first time. Based on this information, different SNM actions could also have been allocated to different ascending/descending pathways and supraspinal regions, whereas acute SNM especially affects regions of learning activity, chronic SNM might result in CNS plasticity even though clinical effectiveness fades after SNM deactivation. Studies to treat fecal incontinence or to prevent detrusor overactivity in complete spinal cord injured patients support the importance of sympathetic pathways for the action of SNM. Despite increasing knowledge about SNM influence on the CNS, the complexity of its underlying working mechanisms is not understood at all. Further investigations with improved functional imaging techniques will enhance our SNM background.