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Physiologic bladder evacuation with selective sacral root stimulation: sinusoidal signal and organ-specific
Karl-Dietrich Sievert1, Curtis A Gleason, Klaus-Peter Jünemann
1Department of Urology, University of California School of Medicine, San Francisco, California, USA. sievertk@uni-muenster.de
Neurourology and Urodynamics
|February 9, 2002
Summary
Sacral anterior root stimulation can improve bladder function after spinal cord injury. Researchers identified specific parameters to achieve selective stimulation, enabling physiologic voiding by fatiguing the sphincter before detrusor activation.
Area of Science:
- Neuroscience
- Urology
- Biomedical Engineering
Background:
- Spinal cord injury above S2 often causes detrusor hyperflexia and sphincteric spasm, complicating bladder management.
- Current sacral anterior root stimulation techniques can evacuate the bladder but often result in non-physiologic voiding due to simultaneous detrusor and sphincter activation (detrusor-sphincter dyssynergia).
- Sacral deafferentation is typically required to address hyperreflexia for normal bladder filling, but this study explores alternative stimulation methods.
Purpose of the Study:
- To determine organ-specific stimulation parameters for selective sacral anterior root stimulation.
- To achieve physiologic bladder emptying by selectively activating the detrusor muscle while managing external urethral sphincter function.
- To investigate methods for inducing sphincteric fatigue prior to detrusor stimulation.
Main Methods:
- Evaluation of rectangular pulse and sinusoidal signal forms with varied parameters (frequency, voltage, electrode placement, bladder filling) on S2 and S3 anterior roots in 20 male dogs.
- Utilized new torpedo-shaped bipolar electrodes adjusted to neural diameter for precise stimulation.
- Developed a protocol involving pre-stimulation of S2 to induce sphincteric fatigue followed by S3 stimulation for detrusor activation.
Main Results:
- Intradural bilateral sinusoidal signal stimulation yielded the best results.
- Sphincteric fatigue was successfully induced by pre-stimulating S2 at 104+/-17 Hz and 0.8+/-0.1 V for 10-15 seconds.
- S3 stimulation at 16+/- 2.1 Hz and 0.4+/-0.1 V evoked a detrusor pressure of 28.7+/-3.0 cm H2O, exceeding the sphincteric pressure.
Conclusions:
- Selective anterior root stimulation with organ-specific parameters can achieve physiologic voiding.
- Inducing initial sphincteric fatigue is a viable strategy to enable controlled and physiologic bladder emptying.
- This approach offers a potential alternative or adjunct to sacral deafferentation for managing bladder dysfunction after spinal cord injury.