Routine Exposure Versus Non-Exposure of Recurrent Laryngeal Nerve during Thyroid Surgery: Our Experience of 300 Cases

The technique of thyroidectomy has been in evolution for many years. It is a basic rule of surgery that an important structure of a human body must be recognized certainly during the surgical procedure in order to prevent its damage. The purpose of this study was to evaluate our routine identification and without identification of recurrent laryngeal nerve during thyroidectomy aiming to lessen the inadvertent injury of the recurrent laryngeal nerve. This retrospective clinical controlled study was performed in the Department of ENT and Head-Neck Surgery, BIRDEM General Hospital and the Department of General Surgery, BIRDEM General Hospital, Dhaka, Bangladesh from January 2014 to December 2018. Patients undergoing indirect laryngoscopy with normal vocal cords and those with carcinoma and re-do surgery having normal vocal cords were included in this study. Patients were excluded like containing hoarseness voice, abnormal movements of vocal cord. The total number of patients was 300 and these patients were randomly divided into two groups of 150 each using random number tables. In Group A the recurrent laryngeal nerves were identified by exposing the inferior thyroid artery and markedly seen in its entire course. Where as, in Group B, nerves were not identified during the operation. Immediate post operative direct laryngoscopy was performed by a surgeon with the help of an Anesthesiologist for the assessment of vocal cords. Patients with either persistent hoarseness of voice or not were followed up with indirect laryngoscopy or fiber optic laryngoscopy (FOL) at three and six months. In Group A, out of 150 patients, 6(4%) patients developed transient unilateral paralysis, resulting in slight hoarseness of voice postoperatively. The voice improved within 6 weeks. While 2(1.3%) patients developed permanent unilateral paralysis of recurrent laryngeal nerve. The voice and cord movement did not return to normal even after 6 months in one case while other one improved within the period of 6 months. In Group B, out of 150 patients, 14(9.3%) patients developed transient paralysis. Out of 14 transient paralysis 11 were unilateral and 3 were bilateral nerve paralysis. The voice was improved within 6 months in all of unilateral and bilateral transient paralyzed cases. While 6(4%) patients developed permanent paralysis of recurrent laryngeal nerve. Out of 6 permanent paralysis 2 cases were of bilateral recurrent laryngeal nerve paralysis required immediate tracheostomy. Rest 4 cases of unilateral permanent nerve paralysis, hoarseness of voice occurred but improved in 2 cases during the period varying from 2 to 6 months while in other 2 cases, it persisted even after 6 months. Frequency of recurrent laryngeal nerve palsies was significantly lower in Group A as compared to Group B. This difference remained statistically significant (p=0.046) between the two groups in terms of type of thyroid diseases, type of surgeries and number of surgeries. For essentially eliminating the risk of nerve injury during surgery, recurrent laryngeal nerve should be exposed and identified routinely in its entire course.