Objective: To study variations in recurrent laryngeal nerve (RLN) bifurcation in extra laryngeal course in neck, to prevent vocal cord palsy due to its damage.
Methodology: This prospective study was completed from October 2020 to March 2021 at anatomy department with the collaboration of general surgery department of Dow University of Health Sciences and Dow Hospital, Ojha Campus, Karachi. A total of 240 RLNs in 120 patients, undergoing thyroid surgery were studied. Cervical course was classified into four segments based on two anatomical landmarks, nerve-artery crossing and laryngeal entry. Four segments were pre-arterial, arterial, post arterial and pre-laryngeal. According to these segments, point of nerve bifurcation was observed and compared on both sides of the neck.
Results: Out of 240 RLNs, 55 (40 cases) were bifurcated. Bilateral bifurcation was found in 15 (12.5%) patients and 30 RLNs. Unilateral bifurcation was found in 25 (20.8%) cases (25 RLNs) including right side bifurcation in 11 (9.2%) and left side bifurcation in 14 (11.7%) cases.
Conclusion: Extra laryngeal bifurcation of RLN is a common variation. In this study bilateral extra laryngeal bifurcation of RLNs were found in 33.3%. Awareness of surgeons of variations in RLNs bifurcation can prevent injury of the nerve and vocal cord paralysis.
Key words: Recurrent laryngeal nerve, nerve bifurcation, anatomic variation, vocal cord palsy, thyroid surgery.