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Functional electrical stimulation of the left recurrent laryngeal nerve with an implanted vagal nerve electrical stimulation device in a normal horse.,

K. Vanschandevijl 1, H. Nollet1, K. Vonck2, P.Boon2, R. Raedt2, Van Roost2, A. Martens1, , P. Deprez1 1 Faculty of Veterinary Medicine, Ghent University, Belgium, 2 Faculty of Medicine, Ghent University Hospital, Belgium

Electrical stimulation of the left recurrent laryngeal nerve (RLN) could offer a potential approach to restore left arythenoid abduction in left laryngeal hemiplegia. The purpose of this investigation was to assess the feasibility of  implantation of a stimulating electrode attached to the left recurrent laryngeal nerve and determine stimulation parameters in order to achieve abduction of the left arytenoid cartilage in a horse with normal arythenoïd function. One normal horse underwent implantation of a Cyberonics vagal nerve stimulation electrode (3.00 mm, model 302) winded around the left RLN and connected to a pulse generator (Cyberonics, model 102) which allows stimulation parameters to be adjusted by a telemetric wand. Intraoperative stimulation and evaluation of arythenoid abduction using a laryngoscope demonstrated abduction of the left laryngeal arythenoid. Postoperative stimulation was performed on the non-sedated horse and stimulus response characteristics were obtained by measuring stimulated arythenoid displacement endoscopically. Stimulus intensities ranging from 0.25 – 1 mA and stimulus frequencies ranging from 1 – 30 Hz were well tolerated by the horse. Video images were digitized and analyzed using Image J and Virtual Dub to measure the change in position of the arythenoid cartilage at rest and during stimulation. Abduction was noted with stimulation frequencies ranging from 2 – 30 Hz and stimulation intensity of 1 mA (pulse width 250 µsec during 30 sec) but a continuous abduction was obtained with stimulation frequencies of 25-30 Hz and intensity of 1 mA (250 µsec pulse width during 30 sec) (figure). These data support the feasibility of implantation of a commercially available stimulation device that allows functional electrical stimulation of the left RLN and could assist in restoring arythenoid abduction in horses with recurrent laryngeal neuropathy.

A                                             B


Endoscopic images of the larynx A left arythenoid before stimulation B abduction of the left arythenoid with stimulation at 25 Hz, 1 mA, 250 µsec, 30 sec

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