A laryngeal pacemaker for inspiration-controlled, direct electrical stimulation of the denervated posterior cricoarytenoid muscle in sheep.

Bilateral recurrent nerve palsies were induced in four sheep and unilateral nerve palsy in one sheep. Vocal cord abductions were achieved by direct electrical stimulation of the posterior cricoarytenoid muscles (PCMs). By means of the diaphragmatic myogram, respiratory synchronous activation of the glottis opening musculature was shown possible. In all cases an adequate glottis opening for respiratory function was achieved during a maximum period of stimulation of 5-8 h in each animal. Abductor movements of the vocal cords were documented with video laryngoscopy. Using digital image processing, the areas of the open glottis were measured at rest and during bilateral direct electrical stimulation of the PCMs.