[Recurrent laryngeal nerve paralysis after thyroid gland operations. Etiology and consequences]

In the period of 1 January 1990 to 31 December 1996 the thyroidectomy cases we performed were immediately followed by vocal cord evaluation using a flexible bronchoscope while the patient was still on the operating table. If an obvious cord paralysis was discovered, an exploration of the recurrent laryngeal nerve, to the level of the larynx, was performed. If the nerve was found to be intact, no further measures were taken. A severed nerve underwent suture repair. If an otolaryngologist diagnosed a vocal cord paralysis 1-5 days after surgery, a reoperation was recommended except in the cases where postoperative bronchoscopy had shown an easily mobile cord or the recurrent nerve was completely dissected during the operation. Within this 7-year period, we performed 3492 thyroidectomy operations. The diagnosis of subsequent unilateral postoperative vocal cord paralysis occurred in 48 cases. In 33 of these cases the status of the nerve in the surgical field was known: 4 patients had an intact nerve proved by complete dissection during thyroidectomy, in two patients the lesions of the nerve were detected intraoperatively (1 transsection, 1 partial resection), and 27 cases were followed by reoperation. Of the 33 patients mentioned above, in 19 instances the recurrent laryngeal nerve was found to be intact; 3 displayed signs of local trauma, and 11 were found to be severed with total discontinuity. Those patients with an intact nerve, or local nerve trauma only, went on to develop normal function within 6 months in 20 (91%) of 22 cases. Of the 11 with a severed nerve, 8 showed "autoparalysis" with good voice within 4-8 months, after suture repair in 10 cases. The patient with partial resection had no repair of the nerve. If immediate postoperative evaluation showed mobility of the vocal cords but a paralysis was detected later by an otolaryngologist and repeat intervention was not done, vocal cord function was spontaneously restored in 9 of 11 patients. Four patients refused reoperation. From 1990 to 1991, the recurrent laryngeal nerve was not always dissected during our thyroidectomy operations. However, this was done routinely from 1991 to 1996. Routine intraoperative dissection of the vocal cord nerve reduced the rate of postoperative cord paralysis from 2.0% to 1.2%. It also reduced the frequency of intraoperative nerve injury with total discontinuity from 0.58% to 0.23%.