Lumbosacral spinal cord epidural stimulation improves voiding function after human spinal cord injury.

Deficits in urologic function after spinal cord injury (SCI) manifest both as a failure to store and empty, greatly impacting daily life. While current management strategies are necessary for urological maintenance, they oftentimes are associated with life-long side effects. Our objective was to investigate the efficacy of spinal cord epidural stimulation (scES) as a promising therapy to improve bladder control after SCI. A bladder mapping study was undertaken for sixteen sessions over the course of four months in an individual with chronic, motor complete SCI. Varying combinations of stimulating cathode electrodes were initially tested during filling cystometry resulting in the identification of an effective configuration for reflexive bladder emptying at the caudal end of the electrode array. Subsequent systematic testing of different frequencies at a fixed stimulus intensity and pulse width yielded lowest post-void residual volumes at 30 Hz. These stimulation parameters were then tested in four additional research participants and found to also improve reflexive voiding efficiency. Taken together with SCI studies on step, stand, voluntary motor control and cardiovascular regulation, these findings further corroborate that scES has an all-encompassing potential to increase the central state of excitability, allowing for the control of multiple body functions, including the urological system.

Training-Induced Functional Gains following SCI.

We previously demonstrated that daily, hour-long training sessions significantly improved both locomotor (limb kinematics, gait, and hindlimb flexor-extensor bursting patterns) and nonlocomotor (bladder function and at-level mechanical allodynia) functions following a moderate contusive spinal cord injury. The amount of training needed to achieve this recovery is unknown. Furthermore, whether this recovery is induced primarily by neuronal activity below the lesion or other aspects related to general exercise is unclear. Therefore, the current study objectives were to (1) test the efficacy of 30 minutes of step training for recovery following a clinically relevant contusion injury in male Wistar rats and (2) test the efficacy of training without hindlimb engagement. The results indicate that as little as 30 minutes of step training six days per week enhances overground locomotion in male rats with contusive spinal cord injury but does not alter allodynia or bladder function. Thirty minutes of forelimb-only exercise did not alter locomotion, allodynia, or bladder function, and neither training protocol altered the amount of in-cage activity. Taken together, locomotor improvements were facilitated by hindlimb step training for 30 minutes, but longer durations of training are required to affect nonlocomotor systems.