Functioning Remobilization of Vocal Cords in Cats with Permanent Recurrent Laryngeal Nerve Paresis

Abstract

From a strictly neuro-physiological standpoint it is shown why a functioning re-innervation of laryngeal muscles is not to be expected after degeneration of the recurrent laryngeal nerve (r.1.n.). It is also shown why at such degeneration the r.1.n., paradoxically as it may seem, should definitely not be used in attempts to re-innervate the larynx. For the same reasons the chances of getting the desired function using an anastomosis with some other nerve and the r.1.n. as the distal part are exceedingly small and accidental. The facts that the posticus muscle has a respiratory function, i.e. contracts at inspiration and that the characteristics of a muscle are mainly determined by its nerve and not vice versa, have been the prime reasons for implanting into the posticus muscle a nerve originally belonging to a muscle with the same respiratory function, the phrenic nerve, which is quiescent at expiration. In this way vocal cords of cats, permanently deprived of their r.1.n. were made to abduct at inspiration, adduction at expiration being performed by the crico-thyreoid muscle. The method is recommended in the case of patients with bilateral paresis of the r.1.n. in order to reduce the breathing difficulties without obtaining an accompanying deterioration of the voice.