Table 3. Classification, definition, and severity of RLN injury (7).

Classification	Definition	Severity
Traction	The RLN running on Berry’s ligament or adhered to the thyroid goiter was pulled and damaged during surgery	Mild
Mechanical injury	During dissection, the RLN was injured by blunt instruments, contusion, pressure, clamping, aspiration, or compression of the trachea by surgical instruments	Mild-moderate
Ligation, suture	During or after nerve dissection, the RLN was ligated or sutured into knots or vascular clips of small vessel branches	Mild-moderate
Thermal injury	When small blood vessels were ligated or connective tissues were dissected at the tracheal groove, the RLN was damaged by direct contact with energy-based devices or transverse thermal spread	Moderate-severe
Complete resection	The RLN was inadvertently severed due to being visually misidentified as a blood vessel or a strip of connective tissue or due to tumor encapsulation and adhesions	Severe

RLN, recurrent laryngeal nerve.