Recurrent laryngeal nerve and voice preservation: routine identification and appropriate assessment – two important steps in thyroid surgery

Abstract

Despite identification and preservation of RLN, patients can develop postoperative voice change and RLNP although all voice change cannot be attributed to damaged RLN. Proper assessment of vocal cord functions by I/L and D/L laryngoscopy is required to rule out injuries to these nerves. Risk of damage is higher in patients undergoing more difficult surgery.

Gender, race, and electrophysiologic characteristics of the branched recurrent laryngeal nerve

“…Bifurcation of the RLN is known to be an important risk factor for postoperative vocal cord paresis. Longer distance of the bifurcation from the NEP has been implicated as a determinant of nerve injury during thyroid surgery . The difference in distance of RLN bifurcation from the NEP between Caucasian patients and African Americans patients does not reach statistical significance in our study ( P = 0.30; Table ).…”

“…Extralaryngeal RLN bifurcation typically occurs within 20 mm of its entry point into the NEP and represents an area of great vulnerability to damage during thyroid surgery (Fig. ) . Here the branched nerve, of a more diminished caliber, is vulnerable to damage by complete transection, compression, and traction.…”

“…2). 3,4 Here the branched nerve, of a more diminished caliber, is vulnerable to damage by complete transection, compression, and traction. In fact, RLNs that branch early and follow a long bifid course have up to twice the risk of injury compared to unbranched variants.…”

Recurrent laryngeal nerve injury (RLNI) in thyroid surgery and its prevention

“…5 Review of literature revealed that the prevalence of RLN palsy varies from centre to centre depending upon the level of experience in thyroid surgery and the nature of surgery. Aytec and colleagues 15 reported 3.5% and 1.2% incidence of transient and permanent RLN injury, respectively and Hayward et al, 7 reported that permanent RLNP occurs in 0.3-3% of cases, with transient palsies in 5-8%, Chaing 14 has reported figures of 5.1% and 0.9% for transient and permanent RLN injury.…”

“…4 Therefore, methods that can reduce the incidence of this complication are of great interest. 5 The most important aspect of effective and safe surgical approach is an adequate knowledge of surgical anatomy and pathophysiology in combination with meticulous handling and dissection of tissue in the correct surgical plane. RLN is located anterior to the tracheoesophageal sulcus (41.6%), posterior to the inferior thyroid artery (35.8%), lateral to Berry's ligament (88.1%), below the inferior rim of the inferior constrictor muscle (90.4%), and entering the larynx before its terminal division (54.6%).…”