student research day - Case Western Reserve University School of ...

Nolan Walther
High Frequency Electrical Conduction Block for Bladder Voiding
Nolan Walther, Adam S. Boger, Narendra Bhadra, Kenneth J. Gustafson
Biomedical Engineering Department
Case Western Reserve University, Neural Engineering Center, Functional Electrical Stimulation
Body of Abstract: (300 word max – 294 currently)
Aims: An implantable spinal sacral nerve stimulating device is currently utilized to allow controlled bladder
voiding in spinal cord injured individuals with bladder dysfunction. However, this implant is frequently performed with a
dorsal rhizotomy, or severing of sensory nerves. This study aimed to demonstrate (1) high frequency alternating current
(HFAC) conduction block at the spinal root level, and (2) a proximal intradural HFAC reversible block of external urethral
sphincter (EUS) reflexes combined with distal extradural intermittent stimulation bladder drive to improve voiding without
a dorsal rhizotomy. Methods: In three dogs and five cats, surgical implantations of nerve cuff electrodes were placed on
distal extradural roots evoking bladder and/or EUS contractions (S1, S2, or S3) and on proximal intradural ventral roots
evoking bladder and EUS contractions (S1+S2 or S2+S3). Trials of proximal stimulation with distal HFAC block, and trials
of distal extradural intermittent stimulation with and without proximal intradural HFAC block were conducted. EUS and
bladder pressures, bladder volumes, and volume voided were recorded. Results: HFAC at the sacral root level partially
blocked EUS and bladder contractions in proximal stimulation and distal HFAC block trials. Applying HFAC block to
proximal intradural ventral sacral roots combined with distal extradural intermittent stimulation yielded no difference in
voiding compared to distal extradural intermittent stimulation alone with large bladder volumes of 80 ml (p=0.8534) or
small bladder volumes of 40 ml (p = 0.3724). Conclusions: HFAC at the sacral root level demonstrated conduction block
of EUS and bladder contractions evoked from a proximal stimulus. Further experimentation is necessary to investigate
the efficacy of proximal intradural ventral sacral root HFAC block combined with distal extradural intermittent stimulation
to allow voiding. Proximal intradural HFAC block may provide an attractive alternative to dorsal rhizotomies
accompanying implantations of extradural intermittent bladder stimulating devices.
Support: VA RR&D B3675R, NIH DK077089, NIH EB004314
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