External laryngeal nerve in thyroid surgery: recognition and surgical implications

Area of Science:

• Anatomy
• Surgery
• Endocrinology

Background:

• Injury to the external laryngeal nerve (ELN) during thyroid surgery is a known complication.
• Surgeons often avoid direct identification of the ELN, increasing risk.
• Understanding ELN anatomy in relation to thyroid structures is vital for safe dissection.

Purpose of the Study:

• To analyze the frequency and types of external laryngeal nerve (ELN) crossing the avascular space.
• To correlate ELN variations with thyroid gland size and pathology.
• To improve ELN identification and preservation techniques during thyroidectomy.

Main Methods:

• Prospective study of 151 consecutive patients undergoing thyroid surgery.
• Documentation of ELN frequency and type as it crossed the potential avascular space.
• Analysis of ELN distribution in relation to goitre weight (>100g) and pathology.

Main Results:

• 202 ELNs (92.7%) were identified; Type 1 (17.3%), Type 2a (56%), Type 2b (26.7%).
• ELNs were not identified in 7.3% of cases, particularly in secondary surgeries or malignant pathology.
• Large goitres (>100g) showed a higher frequency of Type 2b ELN (51.3%).

Conclusions:

• Preserving the external laryngeal nerve (ELN) presents technical challenges.
• Recognizing the avascular space facilitates ELN exposure and preservation.
• Safe dissection techniques are essential to minimize thyroid surgery morbidity.