Differential recurrent laryngeal nerve palsy rates after thyroidectomy

Area of Science:

• Otolaryngology
• Thyroid Surgery
• Nerve Injury

Background:

• Recurrent laryngeal nerve (RLN) palsy is a significant complication following thyroidectomy.
• The precise mechanisms causing RLN palsy, particularly neurapraxia, remain incompletely understood.
• Investigating differential palsy rates and intraoperative factors is crucial for improving patient outcomes.

Purpose of the Study:

• To analyze the differences in palsy rates between the left and right recurrent laryngeal nerves (RLNs) after thyroidectomy.
• To determine if intraoperative nerve swelling is a contributing risk factor for postoperative RLN palsy.
• To explore the relationship between RLN diameter, electromyographic (EMG) activity, and palsy development.

Main Methods:

• Retrospective analysis of thyroidectomy data from 3,408 procedures involving 5,334 RLNs.
• Collected data included patient demographics, intraoperative changes in RLN diameter, and RLN electromyography (EMG) readings.
• Conducted subgroup analyses for left vs. right RLNs and for unilateral vs. bilateral thyroidectomies.

Main Results:

• The overall RLN palsy rate was 1.5%, with higher rates observed on the right in bilateral cases (P = .025) and on the left in unilateral cases (P = .007).
• In a subset of 519 RLNs, nerve diameter increased approximately 1.5-fold (P < .001) during surgery, correlating with increased EMG amplitude (P = .01).
• The right RLN exhibited a larger diameter than the left RLN throughout the dissection (P = .001).

Conclusions:

• Differential RLN diameters appear to contribute to varying palsy rates post-thyroidectomy.
• Smaller diameter nerves may be more vulnerable to stretch-induced edema and subsequent neurapraxia and palsy.
• Surgeons must recognize the distinct vulnerabilities of each RLN to minimize iatrogenic injury during thyroidectomy.