To investigate time of delayed reinnervated laryngeal muscle, 15 dogs were divided into two groups. The right recurrent laryngeal nerves of 10 dogs in experimental group were cut, and repaired at 4, 6, 8, 10 and 12 months intervals by transposition of the phrenic nerve to the recurrent laryngeal nerve after cutting and suturing the adductor branch to the main branch of ansa cervicalis. The right recurrent laryngeal nerves of 5 dogs in control group were cut, but did not repair. Laryngoscope, electromyography, contractile tension of laryngeal muscle and histologic studies were performed at six months postoperatively. The results showed that fair recovery of adduction and abduction was noted within ten months interval, and the effect of adduction was better than that of abduction. The effect decreased gradually with the denervated time increased. The conclusion demonstrated that delayed reinnervation of laryngeal muscle should be performed within ten months.
