During thyroid surgery, a surgeon identifies the recurrent laryngeal nerve (RLN) and notes it is stretched and pale. What is the most common cause of intraoperative RLN injury during total thyroidectomy?

## Most Common Cause of RLN Injury in Thyroid Surgery **Key Point:** Traction injury during dissection of the thyroid lobe is the most frequent mechanism of RLN injury during thyroidectomy, accounting for approximately 60–70% of iatrogenic RLN injuries. ### Mechanism of Traction Injury The RLN has a long, tortuous course and is vulnerable to stretch injury when: - The thyroid lobe is excessively retracted or mobilized without careful nerve identification - Blunt dissection is used aggressively in the tracheoesophageal groove - The nerve is not explicitly identified and protected before lobe mobilization - Lateral traction on the thyroid is applied without recognizing the nerve's position ### Why Traction Is Most Common 1. **Anatomical vulnerability:** The RLN ascends in the tracheoesophageal groove and can be stretched by even modest lateral or cephalad traction on the thyroid lobe. 2. **Frequency of occurrence:** Occurs in routine dissection when the nerve is not identified or when the surgeon relies on "blunt" mobilization. 3. **Preventability:** Identification and gentle handling of the RLN significantly reduces this injury. ### Clinical Pearl **Intraoperative nerve monitoring (IONM)** can detect traction injury early (loss of signal or decreased amplitude) before permanent injury occurs, allowing the surgeon to release traction and potentially prevent permanent paralysis. ### High-Yield Comparison of RLN Injury Mechanisms | Mechanism | Frequency | Timing | Reversibility | Prevention | |-----------|-----------|--------|---------------|------------| | Traction | Most common (60–70%) | During dissection | Partial if released early | Nerve identification, gentle handling | | Thermal (cautery) | ~15–20% | During hemostasis | Rare; usually permanent | Bipolar cautery, avoid nerve contact | | Division | ~10–15% | During hemostasis or dissection | None; requires repair | Direct visualization, careful hemostasis | | Compression (retractor) | ~5–10% | During retraction | Yes, if released promptly | Retractor placement away from nerve | **Clinical Pearl:** Traction injury may be reversible if the nerve is released promptly and IONM shows recovery of signal. Thermal and division injuries are typically permanent. [cite:Sabiston Textbook of Surgery 21e Ch 38]