Delayed Reinnervation of the Paralyzed Larynx: An Experimental Study in the Dog

Respiratory function of the paralyzed animal larynx can be reestablished by implanting the phrenic nerve into the posterior cricoarytenoid muscle immediately after section of the recurrent laryngeal nerve. Clinically, it is not unusual to observe spontaneous return of vocal cord function up to six months from the onset of paralysis when the nerve injury does not involve complete transection. This study was designed to determine the period of denervation within which the posterior cricoarytenoid muscle can be effectively reinnervated by phrenic nerve implant. The degree of functional reinnervation becomes less as the period of denervation increases and there appears to be a time beyond which effective reinnervation is not possible.