Closed -loop electrical control of urinary continence

Individuals with spinal cord injury or neurological disorders may develop involuntary bladder contractions at low volumes (bladder hyper-reflexia) that cause incontinence and can lead to significant health problems. Bladder contractions can be suppressed by electrical stimulation of inhibitory pathways, but continuous activation may lead to habituation of the inhibitory reflex and loss of continence. Conditional stimulation, with stimulation of inhibitory pathways applied only at the onset of nascent bladder contractions, should reduce habituation. Conditional stimulation needs methods of detecting the onset of bladder contractions to trigger inhibitory electrical stimulation. The objectives of this study were to determine if the electrical activity of the pudendal nerve could serve as a control signal for conditional stimulation, to determine whether conditional stimulation allowed the bladder to fill to a greater volume before continence was lost than did continuous stimulation, and to determine whether the techniques developed to detect bladder contractions could be transferred to individuals with a spinal cord injury (SCI).;The electrical activity of the pudendal nerve was modulated during bladder contractions and recordings of the pudendal nerve electroneurogram enabled detection of the onset of reflexive bladder contractions within 2 seconds of the start of the bladder contractions in 9 anesthetized male cats. Conditional electrical stimulation based on the electrical activity of the pudendal nerve allowed the bladder to fill to greater capacity before continence was lost than either continuous stimulation or no stimulation. The techniques developed in preclinical studies were tested on a retrospective clinical data set of 81 subjects with SCI. The activity of the external anal sphincter was modulated in individuals with SCI and enabled detection of the hyper-reflexive bladder contraction. These results indicate that the electrical activity of pudendal nerve can serve as a control signal for conditional inhibitory stimulation, conditional stimulation is more effective at maintaining continence than continuous inhibitory stimulation or no stimulation, and these techniques are transferable to humans with SCI.