Previous attempts at laryngeal transplantation have failed because the grafted organ could not be dynamically rehabilitated. Nerve-muscle pedicles were used to reinnervate each of the principal intrinsic laryngeal muscles in 20 dogs after autotransplantation with conservation of the essential nutrient vessels. Information obtained by sensors fixed to the chest (a strain gauge and transthoracic impedance electrode) was channeled to an electronic package for coordinated stimulation of pedicles reinnervating the posterior cricoarytenoideus (opening), the cricothyroideus (elongation) and the thyroarytenoideus (closure of the vocal cords) by perineural electrodes. Corresponding vocal cord motion was videotaped on the same screen as sensor displacements and stimulating currents (approximately 2 V, 60 Hz, and 4 msec pulse width). Clear responses were recorded in all evaluable animals (n = 8), but contraction was stronger with longer reinnervation time (3-7 weeks). Based on this feasibility study, chronic experiments are planned that will set the ground work for possible future human laryngeal transplantation.
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