SPARC Bladder Mapping and Training Study

Functional Mapping With Lumbosacral Epidural Stimulation for Restoration of Bladder Function After Spinal Cord Injury: Simulation-Based Modeling and Interactive Programming Integration for Bladder Home-Training

The investigators propose to determine the electrode configurations that promote functional gains in the storage and voiding phases of lower urinary tract function as a result of activation of spinal circuits with spinal cord epidural stimulation in humans with spinal cord injury. The innovative approach and novel application of the Medtronic Specify 5-6-5 (16-electrode array) epidural device will allow the investigators to determine, with this early feasibility study, specific parameters of spinal cord epidural stimulation and approaches for bladder training needed for lower urinary tract function which will lay the groundwork for expedient translation of this promising technology to larger numbers of individuals with spinal cord injury who currently have limited treatment options. The current proposed study will increase the understanding of human lumbosacral spinal networks and guide the use of innovative therapeutic strategies that would be immediately available to not only improve the motor output during standing and walking but also ameliorate bladder dysfunction and thus improve quality of life in individuals after spinal cord injury.

Deficits in urologic function after spinal cord injury impact quality of life and consistently ranks as a top priority issue in the spinal cord injury population. Bladder dysfunction may manifest as detrusor hyperreflexia (bladder contractions at low volumes, causing incontinence and smooth muscle hypertrophy), detrusor-sphincter dyssynergia (uncoordinated bladder and external urethral sphincter contractions, causing inefficient emptying and smooth muscle hypertrophy), decreased compliance (unable to store urine under appropriately low pressures) and loss of continence, requiring lifelong management, maintenance, and health care visits. Current therapeutic approaches aim to manage both the storage and voiding phases of bladder function and include intermittent catheterization, pharmacologic and surgical interventions. While most of these strategies are necessary for urological maintenance post-injury they oftentimes are associated with side effects and therefore remain inadequate. Therapies addressing recovery of function are still needed. The use of spinal cord epidural stimulation is a promising alternative approach to addressing the primary phases of bladder dysfunction. Additionally, the effects of spinal cord epidural stimulation on bladder alone is not known as its use has been directed towards the locomotor system. Thus, the overall objective of this study is to perform functional mapping in order to identify the spinal cord epidural stimulation configurations (anode/cathode selection, amplitude, frequency and pulse width) at the lumbosacral level that can promote neural control of bladder storage (capacity) and bladder emptying (voiding efficiency) after spinal cord injury.

Individuals already implanted with a spinal cord epidural stimulator will receive epidural stimulation targeted at enhancing both the storage and voiding phase of micturition cycle.

Spinal cord epidural stimulation will be administered through a multi-electrode array implanted in the epidural space over the dorsum of the spinal cord. An implanted package containing stimulating circuits, rechargeable battery, and wireless communication activates the electrodes (16 platinum electrodes arranged in three columns of [5-6-5]). The pattern of electrically active electrodes, as well as electrode voltage, stimulating frequency, and stimulating pulse width will be varied to facilitate effects toward bladder function.

The quantitative metric for capacity will be the percent change in either residual volume (measured in ml) alone if no leak occurred or residual volume plus leak volume if a reflex void occurred upon reaching capacity.

The quantitative metric for voiding will be the percent change in efficiency (leak volume divided by leak plus residual volumes).

Inclusion Criteria: Implanted with spinal cord epidural stimulator stable medical condition without cardiopulmonary disease or dysautonomia that would contraindicate bladder training; clear indications that the period of spinal shock is concluded determined by presence of muscle tone, deep tendon reflexes or muscle spasms and discharged from standard inpatient rehabilitation; non-progressive supra-sacral SCI (i.e., upper motor neuron re bladder circuitry); - AIS classification A or B; at least 2 years post spinal cord injury; Exclusion Criteria: Painful musculoskeletal dysfunction, unhealed fracture, contracture, pressure sore or urinary tract infection that might interfere with mapping/training; Clinically significant depression or ongoing drug abuse; Pregnant at the time of enrollment or planning to become pregnant during the time course of the study Bladder Botox injections within the past year; Continent diversion procedures with or without bladder augmentation.