Neural reconstruction methods of restoring bladder function

Abstract

During the past century, diverse studies have focused on the development of surgical strategies to restore function of a decentralized bladder after spinal cord or spinal root injury via repair of the original roots or by transferring new axonal sources. The techniques included end-to-end sacral root repairs, transfer of roots from other spinal segments to sacral roots, transfer of intercostal nerves to sacral roots, transfer of various somatic nerves to the pelvic or pudendal nerve, direct reinnervation of the detrusor muscle, or creation of an artificial reflex pathway between the skin and the bladder via the central nervous system. All of these surgical techniques have demonstrated specific strengths and limitations. The findings made to date already indicate appropriate patient populations for each procedure, but a comprehensive assessment of the effectiveness of each technique to restore urinary function after bladder decentralization is required to guide future research and potential clinical application.

Lumbar to sacral root rerouting to restore bladder function in a feline spinal cord injury model: Urodynamic and retrograde nerve tracing results from a pilot study

“…Although nerve rerouting for voluntary voiding is an attractive concept with potential to benefit patients with neurogenic bladder/sphincter dysfunction, there is currently no clinically applicable technique. 7 Our aim was to further evaluate a somatic-to-autonomic nerve transfer technique. It has been hypothesized that a skin-spinal cord-bladder reflex pathway can be created by rerouting a ventral root containing the somatic motor portion of a reflex arc to a ventral root that controls bladder emptying, while keeping the sensory portion of the somatic reflex arc intact (ie, the dorsal root), and that this new pathway may allow bladder emptying in response to somatic sensory stimuli.…”

“…Key priorities for future research endeavors in this field can be found in a recent review article. 7…”

“…6 Therefore, lumbar to sacral rerouting that theoretically allows voiding via a skin-spinal cord-bladder reflex pathway could allow volitional voiding. 7 Human experiments with this technique report either high rates of success (67-100%) or total inefficacy. 1,[8][9][10][11][12][13][14][15][16] Studies in animal models show promise, [17][18][19][20] although methodological limitations include transection of the spinal cord a few months after rerouting rather than before as would occur in SCI patients, and not measuring voiding as an endpoint, preventing extrapolation to SCI patients.…”

Influence of urothelial or suburothelial cholinergic receptors on bladder reflexes in chronic spinal cord injured cats

“…This experimental design may have contributed to the gradual long-term changes in CMG parameters noted in most animals. Despite these deficiencies, the animal model developed in this study which utilized weekly/biweekly urethral catheterization in place of indwelling catheters to monitor bladder function in conscious animals should be useful for examining the efficacy of long-term drug treatments, neuromodulation (de Groat and Tai, 2015), intraspinal therapies (Lee et al, 2013), or peripheral nerve re-routing (Gomez-Amaya et al, 2015) in reversing bladder dysfunction after SCI in a non-rodent, larger animal model.…”

Reversible temporally-specific inhibition of muscle using a light-activated chloride channel

“…Spasticity, for example, results in involuntary muscle contractions that interfere with precise movement and locomotion[1, 2]. In overactive bladder syndrome, excessive activation of the detrusor muscles of the bladder results in unwanted micturition[3, 4].…”