Voice changes after thyroidectomy: role of external laryngeal nerve

ABSTRACT

To evaluate a technique to protect the external laryngeal nerve during thyroidectomy.Randomized controlled trial. Patients randomized into group A or B using closed envelops method. Alexandria university hospital is a teaching hospital. It is the referral center serving seven million people. Forty four consecutive patients admitted to Alexandria university hospital for thyroidectomy. Fourpatients had voice abnormalities on preoperative voice analysis. They were excluded. All patients underwent thyroidectomy. Group A had conventional mass ligature of the superior poleof thyroid gland while group B had individual ligation of the branches of the superior thyroid artery afteridentification of the external laryngeal nerve whenever possible. Abnormal readings on postoperative voice analysis and abnormal electromyogram of thecricothyroid muscles. Observers performing voice analysis tests were blinded as regards patient group. Postoperativeelectromyography of the cricothyroid revealed signs of nerve injury in five patients of group A but none in groupB. Multi-dimensional voice program, fundamental frequency range, fundamental frequency and maximum pressurelevel all showed significant postoperative change in group A but not of those in group B [level of confidence95%].Identification of external laryngeal nerve and/or ligation of the terminal branches of the superiorthyroid vessels seems to help prevent external laryngeal nerve injury