title: Conditioning stimulus can influence an external urethral sphincter contraction evoked by a magnetic stimulation.
abstract: OBJECTIVE
  To study the effect of a conditioning stimulus on an external urethral sphincter (EUS)contraction evoked by a magnetic stimulation at different time intervals.
  
  
  METHODS
  Seven healthy male volunteers underwent EUS pressure measurement. At baseline, magnetic stimulation of the lumbosacral spinal cord above the motor threshold was performed and evoked EUS pressure responses were recorded. The lumbosacral magnetic stimulation was repeated with same intensity, while a selective electrical dorsal penile nerve stimulation below the bulbocavernosus reflex (BCR) threshold was preceding at five different intervals (10, 20, 30, 50, 100 msec). The protocol was performed with empty and full bladder (BLA), and baseline responses were statistically compared to those with combined stimulation.
  
  
  RESULTS
  When the dorsal penile nerve electrical stimulation preceded the lumbosacral magnetic stimulation by 20 msec (P=0.0048), 50 msec (P=0.0039), or 100 msec (P=0.0002), the amplitudes of the EUS pressure response with empty BLA were significantly reduced compared to lumbosacral magnetic stimulation alone. With a filled BLA, the amplitudes of the EUS were significantly reduced only at an interval of 50 msec (P<0.0001).
  
  
  CONCLUSIONS
  A conditional sensory pudendal stimulation seems to have the capacity to inhibit the external urethral sphincter contraction induced by a magnetic stimulation. The inhibitory effect seems to depend on the latency between the peripheral and lumbosacral stimulation as well as on the degree of BLA filling. It remains to be proved if the neuromodulative effect of the conditional stimulus occurs at a spinal or supraspinal level.
authors.affiliation: Neuro-Urology, Swiss Paraplegic Center, Balgrist University Hospital, Zurich, Switzerland. bjoern.wefer@balgrist.unizh.ch
authors.forename: Bjoern
authors.initials: B
authors.lastname: Wefer
authors.forename: André
authors.initials: A
authors.lastname: Reitz
authors.forename: Peter A
authors.initials: PA
authors.lastname: Knapp
authors.forename: Andreas
authors.initials: A
authors.lastname: Bannowsky
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Juenemann
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schurch
mesh_terms: D000328:Adult; D003213:Conditioning, Psychological; D004558:Electric Stimulation; D004574:Electromagnetic Fields; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000294:innervation / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D010413:Penis / Q000294:innervation; D011312:Pressure; D012018:Reflex / Q000502:physiology; D014521:Urethra / Q000502:physiology*; D001743:Urinary Bladder / Q000294:innervation / Q000502:physiology; D014563:Urodynamics / Q000502:physiology