Neural Prosthetic Control of Continence and Micturition

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Loss of bladder control as a result of neurological disease or injury such as spinal cord injury (SCI) has devastating effects. SCI results in loss of voluntary control of bladder evacuation, bladder hyper-reflexia, and bladder sphincter dysynergia. These factors often lead to ureteric reflux and obstruction, infection of the kidneys, long-term renal damage, episodes of autonomic dysreflexia with dangerous rises in blood pressure, incontinence which contributes to skin breakdown, as well as frequent urinary tract infections. Loss of bladder control also has profound social impact and leads to decreased quality of life, as well as large direct medical costs from procedures, supplies, and medication. The long-term goal of this research is to develop a neural prosthesis to restore bladder function (continence and micturition) in persons with neurological disorders, particularly spinal cord injury. Restoration of bladder evacuation and continence in individuals with SCI by electrical stimulation of the sacral nerve roots and surgical transection of sacral sensory nerve roots (dorsal rhizotomy) has resulted in documented medical, quality of life, and financial benefits. However, the widespread application of existing technology is limited by the objection of potential candidates to the irreversible dorsal rhizotomy and the complex surgical implant procedure. We propose an innovative approach to restoration of bladder function using a single multi-electrode nerve cuff implanted on the pudendal nerve to detect the onset of hyper-reflexive bladder contractions by electrical recording, to arrest nascent hyper-reflexive bladder contractions by electrical stimulation of pudendal genital afferent nerve fibers, and to produce on-demand bladder evacuation by electrical stimulation of pudendal urethral afferent nerve fibers. This innovative approach differs substantially from existing approaches using electrical stimulation of the spinal roots in that it does not require a spinal laminectomy, does not require irreversible surgical transection of the sacral sensory nerve roots, and stimulates the afferent rather than the efferent side of the system. This is expected to increase the population of individuals who can benefit from neural prosthetic technology, while maintaining the documented benefits. The objective of the proposed work is to demonstrate the feasibility of this approach using complementary experiments in an animal model and in persons with spinal cord injury. Successful completion of this project will lead to the development of an effective neural prosthetic system for restoration of bladder function.