[Laryngeal reinnervation for unilateral recurrent laryngeal nerve injuries caused by thyroid surgery]

To explore the protocols and effects of laryngeal reinnervation for unilateral recurrent laryngeal nerve (RLN) injury caused by thyroid surgery.

Different protocols of laryngeal reinnervation were performed upon 29 patients with unilateral recurrent laryngeal nerve injury caused by thyroid surgery, just coming on to with a course of 2 years, including nerve decompression upon 8 cases, end to end anastomosis of recurrent laryngeal nerve upon 6 cases, and anastomosis of main branch of ansa cervicalis to recurrent laryngeal nerve upon 15 cases. All were been subjected to preoperative and postoperative voice recording, acoustic analysis, videolaryngoscopy, stroboscopy and electromyography.

Nerve decompression had restored the normal functional adductory and abductory motion of the vocal cord in 5 patients with a course of less than four months. Although functional motion of vocal cord had not been recovered in three patients who received nerve decompression, 2 being with a course of longer than 4 months and one with a course of less than 4 months, and in all cases who received ansa cervicalis anastomosis and end to end anastomosis of recurrent laryngeal nerve, these procedures resulted in medialization of vocal cords except in two cases, one receiving ansa cervicalis anastomosis, and the other receiving end to end anastomosis of RLN. Acoustic parameters (Jitter, Shimmer, NNE) measured 6 months after operation of any kind all returned to normal, however, without significant difference among different groups (P > 0.05). The amplitude of evoked potential of reinnervated laryngeal muscles was significantly greater in the group of nerve decompression than in the group of end to end anastomosis of RLN and group of ansa cervicalis anastomosis (both P < 0.05). However, the amplitude of evoked potential of reinnervated laryngeal muscles between the latter two groups was not significantly different (P > 0.05). Except in one case in the end to end anastomosis of RLN group and one case in the ansa cervicalis anastomosis group, the mass and tension of the reinnervated vocal cord became much the same as the contralateral normal vocal cord and symmetric vibration of the vocal cords and physiological phonation were recovered in all cases.

(1) Nerve decompression is the best procedure in laryngeal reinnervation. (2) Main branch of ansa cervicalis anastomosis and end to end anastomosis of RLN effectively restore the laryngeal vocalization. (3) Selection of the laryngeal reinnervation protocols should depend on the course, severity and type of nerve injury.