title: Repeated assessment of larynx compound muscle action potentials using a self-sizing cuff electrode around the vagus nerve in experimental rats.
abstract: BACKGROUND
  Vagus nerve stimulation (VNS) is an adjunctive treatment for patients with refractory epilepsy. In more than 30% of the patients VNS has no therapeutic effect. The goal of this study was to find an objective parameter that can be used as an indicator of effective stimulation of the vagus nerve.
  
  
  METHODS
  The electrophysiological response to VNS was recorded from the vagus nerve, recurrent laryngeal nerve and larynx muscles. Nerve lesions and muscle relaxing agent were used to find the source of the electrophysiological response. A cuff-electrode for chronic stimulation and recording was implanted for chronic recording of the VNS-induced electrophysiological response after implantation. Dose-response curves were determined daily during a follow-up period of 2 months.
  
  
  RESULTS
  VNS induced an electrophysiological response around 3 ms after start of the stimulation. This response was identified as a larynx compound action potential (LCMAP) LCMAP could be recorded immediately after surgery in 11/21 rats, while in the other 10/21 rats, a recovery period with an average of 25 days was required. Once the LCAMP could be recorded, the latency and overall characteristics of the doses response curves of the LCMAP remained stable during the entire follow-up period.
  
  
  CONCLUSIONS
  In this study, we provide an objective electrophysiological parameter for vagus nerve activation. LCAMP may indicate recovery of the vagus nerve after implantation, which may help to determine when uptitration of VNS therapy can be initiated. LCAMP could be of value in future experiments for objectification of VNS in animal models for epilepsy.
authors.affiliation: Ghent University Hospital, Laboratory for Experimental and Clinical Neurophysiology, De Pintelaan 185, 9000 Gent, Belgium. Riem.Eltahry@ugent.be
authors.forename: Riëm
authors.initials: R
authors.lastname: El Tahry
authors.forename: Lies
authors.initials: L
authors.lastname: Mollet
authors.forename: Robrecht
authors.initials: R
authors.lastname: Raedt
authors.forename: Jean
authors.initials: J
authors.lastname: Delbeke
authors.forename: Veerle
authors.initials: V
authors.lastname: De Herdt
authors.forename: Tine
authors.initials: T
authors.lastname: Wyckhuys
authors.forename: Dimitri
authors.initials: D
authors.lastname: Hemelsoet
authors.forename: Alfred
authors.initials: A
authors.lastname: Meurs
authors.forename: Kristl
authors.initials: K
authors.lastname: Vonck
authors.forename: Wytse
authors.initials: W
authors.lastname: Wadman
authors.forename: Paul
authors.initials: P
authors.lastname: Boon
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D004567:Electrodes, Implanted; D007821:Laryngeal Muscles / Q000502:physiology*; D007823:Laryngeal Nerves / Q000502:physiology*; D051381:Rats; D014630:Vagus Nerve / Q000502:physiology*; D055536:Vagus Nerve Stimulation / Q000379:methods*