title: Intraurethral stimulation for reflex bladder activation depends on stimulation pattern and location.
abstract: OBJECTIVE
  Reflex bladder excitation has been demonstrated by stimulation of the pudendal nerve and several of its distal branches. However, excitation parameters have not been consistent and the relationship to anatomical locations within the urethra has not been fully investigated. An improved understanding of the lower urinary tract neurophysiology will improve human studies and neuroprosthetic device development.
  
  
  METHODS
  Intraurethral stimulation was performed in nine cats at near isovolumetric bladder volumes before and/or after spinalization. Bladder excitability profiles were obtained for lower (2 Hz) and higher (33 Hz) frequency stimuli along the urethra between the bladder neck and external meatus.
  
  
  RESULTS
  Higher frequency stimuli were excitable at all urethral locations prior to spinalization but only excitable in the middle and distal urethra after spinalization. Lower frequency stimuli were excitable at proximal and middle locations before spinalization but not excitable at any location after spinalization. In most evaluations, bursting pulse stimulation patterns evoked greater bladder pressures than the dominant continuous frequency (2 or 33 Hz).
  
  
  CONCLUSIONS
  These data indicate the potential presence of two distinct pathways for reflex bladder activation within the urethra: a supra-T10 circuit initiated in the proximal and mid urethra that responds to lower and higher frequency stimuli, and a sacral circuit initiated in the mid and distal urethra that responds to higher frequency stimuli. This work suggests potential anatomical targets and stimulus patterns for clinical evaluations of peripheral nerve-based neuroprostheses for bladder control.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. tmb30@case.edu
authors.forename: Tim M
authors.initials: TM
authors.lastname: Bruns
authors.forename: Narendra
authors.initials: N
authors.lastname: Bhadra
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Gustafson
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology; D002415:Cats; D004558:Electric Stimulation / Q000379:methods; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000294:innervation*; D009434:Neural Pathways / Q000502:physiology; D011312:Pressure; D012018:Reflex / Q000187:drug effects; D012445:Sacrococcygeal Region; D013116:Spinal Cord / Q000601:surgery; D013127:Spinal Nerves / Q000187:drug effects / Q000502:physiology*; D014521:Urethra / Q000294:innervation*; D001743:Urinary Bladder / Q000294:innervation*
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine