title: High frequency sacral root nerve block allows bladder voiding.
abstract: OBJECTIVE
  Dyssynergic reflexive external urethral sphincter (EUS) activity following spinal cord injury can prevent bladder voiding, resulting in significant medical complications. Irreversible sphincterotomies or neurotomies can prevent EUS activation and allow bladder voiding, but may cause incontinence or loss of sacral reflexes. We investigated whether kilohertz frequency (KF) electrical conduction block of the sacral roots could prevent EUS activation and allow bladder voiding.
  
  
  METHODS
  The S2 sacral nerve roots were stimulated bilaterally to generate bladder pressure in six cats. One S1 nerve root was stimulated proximally (20 Hz biphasic pulse trains) to evoke EUS pressure, simulating worst-case dyssynergic EUS reflexes. KF waveforms (12.5 kHz biphasic square wave) applied to an electrode implanted distally on the S1 nerve root blocked nerve conduction, preventing the increase in EUS pressure and allowing voiding.
  
  
  RESULTS
  Applying KF waveforms increased bladder voiding in single, limited-duration trials from 3 ± 6% to 59 ± 12%. Voiding could be increased to 82 ± 9% of the initial bladder volume by repeating or increasing the duration of the trials.
  
  
  CONCLUSIONS
  Sacral nerve block can prevent EUS activation and allow complete bladder voiding, potentially eliminating the need for a neurotomy. Eliminating neurotomy requirements could increase patient acceptance of bladder voiding neuroprostheses, increasing patient quality of life and reducing the cost of patient care.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Boger
authors.forename: Narendra
authors.initials: N
authors.lastname: Bhadra
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Gustafson
mesh_terms: D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D008160:Lumbosacral Plexus; D008297:Male; D009431:Neural Conduction; D058117:Neural Prostheses; D011312:Pressure; D012018:Reflex; D013126:Spinal Nerve Roots; D013997:Time Factors; D014521:Urethra / Q000294:innervation*; D001743:Urinary Bladder / Q000294:innervation*; D001750:Urinary Bladder, Neurogenic / Q000503:physiopathology / Q000628:therapy*; D014554:Urination; D014563:Urodynamics