title: Inhibition and Excitation of Bladder Function by Tibial Nerve Stimulation Using a Wirelessly Powered Implant: An Acute Study in Anesthetized Cats.
abstract: OBJECTIVE
  Tibial nerve stimulation is a minimally invasive neuromodulation treatment of overactive bladder. However, in addition to our limited understanding of the underlying mechanisms, there are also questions regarding the long-term delivery of tibial nerve stimulation therapy in patients. We aimed to characterize the effects of stimulation frequency using a wirelessly powered implantable stimulation device.
  
  
  METHODS
  Six α-chloralose anesthetized adult male cats were used in this study. A multicontact lead was surgically implanted subcutaneously in the hind limb and used to stimulate the tibial nerve. Using an isovolumetric bladder a short duration of electrical pulses was applied at amplitudes 3 times the motor threshold and at frequencies from 2 to 20 Hz.
  
  
  RESULTS
  Implant driven stimulation of the tibial nerve resulted in frequency dependent activation of bladder reflexes. Low frequency tibial nerve stimulation (2 Hz) consistently evoked excitatory responses (mean ± SE 32.9% ± 3.8%). In contrast, higher frequency tibial nerve stimulation (6 to 20 Hz) inhibited bladder function (overall mean 14.9% ± 2.4%). Although low foot motor thresholds were achieved at initial implantation (mean 0.83 ± 0.05 mA), a notable elevation in threshold amplitude was observed 5 hours after implantation.
  
  
  CONCLUSIONS
  To our knowledge this study provides the first evidence of frequency dependent modulation of bladder function in anesthetized cats. The inhibitory influence of tibial nerve stimulation at frequencies above 6 Hz transitioned to an excitatory effect at 2 Hz. Taken together these preclinical data support the feasibility of using a wirelessly powered implantable device to potentially modulate bladder function in patients.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Moazzam
authors.affiliation: Nuviant Medical, Inc., Dallas, Texas.
authors.forename: Austin R
authors.initials: AR
authors.lastname: Duke
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada. Electronic address: paul.yoo@utoronto.ca.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Yoo
mesh_terms: D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D004599:Electric Stimulation Therapy / Q000379:methods*; D004567:Electrodes, Implanted; D004576:Electromyography; D008297:Male; D013979:Tibial Nerve / Q000503:physiopathology*; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000503:physiopathology*; D053201:Urinary Bladder, Overactive / Q000503:physiopathology / Q000628:therapy*; D059015:Wireless Technology
keywords: cats; implantable neurostimulators; tibial nerve; urinary bladder, overactive; wireless technology