Micturitional assist device
First Claim
1. A method of controlling bladder discharge in which detrusor activation for contracting the bladder is controlled by action potentials passing along smaller diameter nerve fibers of a sacral root and in which contraction of a urethral sphincter for closing an outlet from the bladder is caused by action potentials passing along larger diameter nerve fibers of the sacral root, the method of controlling bladder discharge comprising:
- electrically exciting action potentials on at least the smaller diameter nerve fibers, whereby the detrusor is activated to cause contraction of the bladder;
concurrently blocking action potentials from passing along the larger diameter nerve fibers, whereby the urethral sphincter is permitted to relax.
1 Assignment
0 Petitions
Accused Products
Abstract
Cuff electrodes (40a, 40b) are surgically implanted around S3 sacral ventral root nerve trunks (16a, 16b). The sacral ventral roots have smaller diameter nerve fibers (20a, 20b) which convey action potentials to cause detrusor activation to contract the bladder (10) and larger diameter nerve fibers (18a, 18 b) which carry action potentials for causing contraction of a urethral sphincter (12) to block the flow of urine from the bladder. A current source (50) causes current pulses (52) between such electrical contacts (46, 48) and a central electrical contact (44). The current pulses have an appropriate amplitude and waveform to initiate action potentials adjacent the central contact and to block the propagation of action potentials adjacent the end electrodes along the larger diameter nerve fibers (which have fewer nodes between the contacts) but not the smaller diameter nerve fibers (which have more nodes between the electrodes). In this manner, action potentials are electrically excited to propagate at least downstream on the smaller diameter nerve fibers causing contraction of the bladder. Concurrently, blocking action potentials are allowed to propagate upstream on at least the larger diameter nerve fibers, collision blocking naturally occurring action potentials propagating downstream. The transmission of action potentials downstream on the larger diameter nerve fibers is blocked by the current pulses allowing the urinary sphincter to relax.
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Citations
13 Claims
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1. A method of controlling bladder discharge in which detrusor activation for contracting the bladder is controlled by action potentials passing along smaller diameter nerve fibers of a sacral root and in which contraction of a urethral sphincter for closing an outlet from the bladder is caused by action potentials passing along larger diameter nerve fibers of the sacral root, the method of controlling bladder discharge comprising:
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electrically exciting action potentials on at least the smaller diameter nerve fibers, whereby the detrusor is activated to cause contraction of the bladder; concurrently blocking action potentials from passing along the larger diameter nerve fibers, whereby the urethral sphincter is permitted to relax. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of selectively, concurrently exciting and blocking the excitation of first and second end organs which are controlled by small and large diameter nerve fibers, respectively, of a common nerve trunk, the method comprising:
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electrically exciting action potentials on at least the smaller diameter nerve fibers; concurrently blocking action potentials from passing along the larger diameter nerve fibers toward the second end organ. - View Dependent Claims (9, 10, 11, 12)
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13. An electrical system for selectively controlling evacuation of a patient'"'"'s bladder by concurrently generating action potentials on smaller diameter nerve fibers which cause contraction of the patient'"'"'s bladder and suppressing action potentials in larger diameter nerve fibers connected with the patient'"'"'s urethral sphincter to allow the urethral sphincter to relax, the larger and smaller diameter nerve fibers originating in part in left and right S2 sacral roots, left and right S3 sacral roots, and left and right S4 sacral roots, the electrical system comprising:
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a first cuff electrode at least partially encircling the left S3 sacral root; a second cuff electrode at least partially encircling the right S3 sacral root; a third cuff electrode at least partially encircling the left S4 sacral root; a fourth cuff electrode at least partially encircling the right S4 sacral root; each of the first, second, third, and fourth cuff electrodes including a central electrical contact, an antidromic end electrical contact, and an orthodromic end electrical contact, each of the cuff electrodes being implanted at least partially encircling the respective root with its antidromic end disposed closer to the patient'"'"'s spinal column than its orthodromic end; a current source means connected between the end electrical connectors and the central electrical connector of each cuff electrode for selectively applying quasi-trapezoidal shaped current pulses have a generally flat plateau and an exponentially decaying tail; a means for adjusting an amplitude of the current pulses such that (i) a substantially -25 millivolt potential relative to a resting potential is created across membranes of nodes of the larger and smaller diameter nerve fibers to depolarize the nodes and initiate propagation of action potentials on the larger and smaller diameter nerve fibers and (ii) a hyperpolarizing potential of about 55 millivolts more negative than the resting potential is created across the nodes of the larger diameter nerve fibers blocking orthodromic propagation of action potentials on the larger diameter fibers without blocking orthodromic action potential propagation on the smaller diameter nerve fibers.
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Specification