Surgical anatomy of recurrent laryngeal nerve during thyroid and laryngeal surgeries

Abstract

INTRODUCTION:A correct knowledge of variations in regional neurovascular anatomy is essential for preventing complications during surgery in neck. The most important anatomic structures during thyroidectomy include the arteries and veins of thyroid gland, the position of the parathyroid glands and the position of the laryngeal nerves. Recurrent Laryngeal Nerve (RLN) is a branch of vagus nerve. The right RLN arises from the vagus nerve in the superior part of the thorax crosses the undersurface of the right subclavian artery and ascends in the neck and the left RLN hooks around the arch of aorta and ascends more vertically in the neck before reaching its point of penetration in the larynx. RLN palsy is a serious iatrogenic complication of the thyroid surgery which can cause hoarseness and breathing difficulties. Moreover, this palsy can be responsible for major psychological and social disturbance for the patients. The route of the RLN is not always consistent but it must be identified and dissected completely in the thyroid region during the surgery, in order to preserve it from iatrogenic injury. 1 The reported incidence of vocal cord paralysis has fallen over the last several decades due to improved experience of surgeons and better knowledge of anatomical details of the RLN. Still the incidence of postoperative vocal cord paresis or paralysis in recent large series is reported up to 5% for temporary and 0.5% for permanent paralysis. 2 Identification of the RLN early during thyroid surgery is important so as to avoid its inadvertent injury. This study was conducted with the objective of identifying the variations in RLN and its relation to the surrounding structures in patients undergoing thyroid and the laryngeal surgeries as this is the key in avoiding iatrogenic RLN injuries. MATERIALS AND METHODS:This is a descriptive prospective study conducted in the department of Otorhinolaryngology and Head and Neck surgery in BPKIHS, Dharan, between July 2008-June 2009. All patients undergoing thyroidectomy and total laryngectomy were included where the RLN could be traced to the extent technically possible by operating surgeon without jeopardizing the nerve and the intra-operative observations were noted. For measuring the thickness of the nerve it was compared with the thickness of electrical copper wire ranging in thickness from 10 to 20 gauges and its exact diameter was measured in mm with micrometer screw gauge. Prior ethical clearance was obtained from the institute's ethical committee. All photographic records were taken by Cannon Power Shot A620 7.1 mega pixels digital camera from an angle of about 45° to the body and a distance of 15 cm without using any zoom. Analysis of the data was done using appropriate statistical method (SPSS 14 for windows). Objective:To determine the anatomic relationship of recurrent laryngeal nerve with inferior thyroid artery, tracheo-oesophageal groove and Berry's ligament and to determine the thickness and terminal branching pattern of recurrent laryngeal nerve. Material and Meth...