Reflex inhibition of urethral sphincters to permit voiding in paraplegia

Spinal cord stimulation for the restoration of bladder function after spinal cord injury

Spinal cord injury (SCI) results in the inability to empty the bladder voluntarily, and neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD) negatively impact both the health and quality of life of persons with SCI. Current approaches to treat bladder dysfunction in persons with SCI, including self-catheterisation and anticholinergic medications, are inadequate, and novel approaches are required to restore continence with increased bladder capacity, as well as to provide predictable and efficient on-demand voiding. Improvements in bladder function following SCI have been documented using a number of different modalities of spinal cord stimulation (SCS) in both persons with SCI and animal models, including SCS alone or SCS with concomitant activity-based training. Improvements include increased volitional voiding, voided volumes, bladder capacity, and quality of life, as well as decreases in NDO and DSD. Further, SCS is a well-developed therapy for chronic pain, and existing Food And Drug Administration (FDA)-approved devices provide a clear pathway to sustainable commercial availability and impact. However, the effective stimulation parameters and the appropriate timing and location of stimulation for SCS-mediated restoration of bladder function require further study, and studies are needed to determine underlying mechanisms of action.

Novel multi-system functional gains via task specific training in spinal cord injured male rats

Locomotor training (LT) after spinal cord injury (SCI) is a rehabilitative therapy used to enhance locomotor recovery. There is evidence, primarily anecdotal, also associating LT with improvements in bladder function and reduction in some types of SCI-related pain. In the present study, we determined if a step training paradigm could improve outcome measures of locomotion, bladder function, and pain/allodynia. After a T10 contusive SCI trained animals (adult male Wistar rats), trained animals began quadrupedal step training beginning 2 weeks post-SCI for 1 h/day. End of study experiments (3 months of training) revealed significant changes in limb kinematics, gait, and hindlimb flexor-extensor bursting patterns relative to non-trained controls. Importantly, micturition function, evaluated with terminal transvesical cystometry, was significantly improved in the step trained group (increased voiding efficiency, intercontraction interval, and contraction amplitude). Because both SCI and LT affect neurotrophin signaling, and neurotrophins are involved with post-SCI plasticity in micturition pathways, we measured bladder neurotrophin mRNA. Training regulated the expression of nerve growth factor (NGF) but not BDNF or NT3. Bladder NGF mRNA levels were inversely related to bladder function in the trained group. Monitoring of overground locomotion and neuropathic pain throughout the study revealed significant improvements, beginning after 3 weeks of training, which in both cases remained consistent for the study duration. These novel findings, improving non-locomotor in addition to locomotor functions, demonstrate that step training post-SCI could contribute to multiple quality of life gains, targeting patient-centered high priority deficits.