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Stimulator design and subsequent stimulation parameter optimization for controlling micturition and reducing urethral
M Sawan1, M M Hassouna, J S Li
1Department of Electrical and Computer Engineering, Ecole Polytechnique de Montréal, P.Q., Canada.
IEEE Transactions on Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society
|March 1, 1996
Summary
A new implantable electrical stimulation system enables bladder evacuation in dogs with spinal cord injuries. This system reduces bladder outlet resistance by fatiguing the external sphincter, promoting effective bladder emptying without nerve damage.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Urology
Background:
- Spinal cord transection often leads to impaired bladder function and urinary retention.
- Current management strategies may involve invasive procedures like sacral nerve rhizotomies or pudendal nerve neurectomies.
- Developing less invasive methods for restoring bladder evacuation is crucial for improving patient quality of life.
Purpose of the Study:
- To evaluate an implantable computerized electrical stimulation system for inducing bladder evacuation in animal models with spinal cord transection.
- To determine optimal stimulation parameters for achieving effective bladder emptying by inducing reversible external sphincter fatigue.
- To assess the system's ability to reduce bladder outlet resistance without requiring destructive nerve procedures.
Main Methods:
- Development and evaluation of a fully programmable, handheld electrical stimulation system with a multichannel miniaturized stimulator.
- Application of pudendal nerve stimulation to induce reversible fatigue of the external sphincter, thereby reducing bladder outlet resistance.
- Systematic study in four chronically affected dogs to identify optimal stimulation parameters (amplitude, frequency modulation, pulse width, stimulation duration, fatiguing duration).
Main Results:
- The developed system successfully induced bladder evacuation in dogs with spinal cord transection.
- Optimal parameters identified included specific amplitude, frequency modulation (200 Hz modulated by 10 Hz), duty cycle (20%), sacral nerve stimulation duration (50 s), and fatiguing duration (20 s).
- The stimulation effectively reduced bladder outlet resistance, leading to proper bladder emptying without the need for sacral nerve rhizotomies or pudendal nerve neurectomies.
Conclusions:
- The implantable electrical stimulation system offers a promising, less invasive approach for restoring bladder function after spinal cord injury.
- Inducing reversible external sphincter fatigue via pudendal nerve stimulation is an effective strategy for achieving bladder evacuation.
- This technology has the potential to significantly improve management of neurogenic bladder dysfunction.